@fleschler
Maybe microphonics are not an issue with cathode followers.
I just don’t understand VAC using only 6SN7s in all their current amplifiers if they are worse than 6SL7s. VAC is likely using them because thats what the current customer base has been told its the tube to have. Cathode followers have a gain of 1. 6SN7s have a gain of 20 when used for line gain. The Microphonic sensitivity is thus 20 times less in the follower. SNs and SLs are not interchangeable, nor meant to be. They are two different animals. SNs run at almost 10 times the current and most circuits would not bias up properly. Do you know if your circuit is a cathode biased or a constant current biased follower? Makes a big difference when you swap tubes. big big big 2 seconds and a schematic will answer that question. I thank you for this question because, with additional information and some simple schematic understanding, we might come with an alternative answer to what is going on. We really dont know why these differences between tubes exist. Or if these same things would be heard in another preamp that had the other kind of circuit. In other words, is the difference really in the tube alone or more likely how the tube performs in your circuit. |
@tomic601
thanks for awesome thread Roger
i got to page 27 of the Williams book and he says “ but as you learned in your AC theory course... “
so....now what book do I need ? Dont answer, I will figure it out...
Tektronix scope is on order...@$&*(#### this is fun.
You are the first one here to report diving into the pool! Dont worry too much about the AC theory, thats is likely to get into AC power, 3 phase motors, things not important. Read how tubes and transistors work and then the simple circuits to the complex. He does that very well.
If power supplies interest you that is fairly easy stuff. I forget if he does much or anything with tubes, but for now transistors do the same basic things, they amplify.
|
@oldtecg05
Whose thread is this?
I thought it was mine. I dont mind a bit of controversy as long as its Gentlemanly and with some sense of humor. Its the sense humor that I find lacking. |
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@atmasphere It is in no way an excuse for bad specs- and in fact our amps have some pretty good specs (if proper measurement technique is used, which means **don’t ground a speaker terminal during testing**, which is the mistake that almost everyone except Charles Hanson made/makes). I suspect you didn’t read the paper at the link very carefully, since you claimed that you read it, yet still with the remonstrations! Do you think I am so stupid as to ground floating outputs. GEEEEZ Get off my back. I go into the balanced input of the Soundtech. Ive given your amplifier every opportuinty to meet your specs and it just does not. Would you like to send me one that does? Ive measured you feedback to be less than 0.1 db with an 8 ohm load. I simply disconnected the feedback and the meter moved less than 0.1 dB. Is that how you measure it? Output regulation is about 9 dB at 450 mA idle and is certainly idle dependent. Distortion I can never get below 1% unless I really want to heat up the tubes. Ive read you paper to death and makes little sense to me or anyone skilled in the art. Rather than me keep reading it how about you work on re-writing it. Im happy to help. The history of the 6SN7, has nothing to do with its current use. Shall we publish the 6SN7 application notes for the whole RC series? Will the writing make it a better tube? All I know about your amplifier is that if I add 12 dB of feedback it sounds a lot better to everyone that has come to hear it. Perhaps you have not tried this much. Because the amp has good stability it takes this feedback nicely and gets us under 1% THD and a regulation of 3 dB vs 9 dB. Makes the QUAD 57 sound really nice in brushes, clean tuneful bass, clear vocals. Why are you so opposed to feedback? Ive read Crowhurst, he taught me how to make good transformers. I dont go looking for amps to modify, other people modify my amps. All they do is put in silly fast rectifiers. WOW. People modify cars. If 12 dB of feedback makes the M-60 sound better to all the people I have demonstrated if for then it does for them. Look, It seems we have hit a nerve here, lets be nice and lets all try to make better amps and less story.
Actually Roger, I did that earlier. You must not have read the post?
The loading is for the benefit of the preamp, if its sensitive to RFI. If not, no loading is needed. IOW if you need loading to deal with brightness, the preamp has a problem with RFI. The loading resistor detunes the tank circuit caused by the cartridge and tone arm cable and thus knocks out the RFI caused by the tank circuit when driven into excitation by the energy of the cartridge. Here’s a couple of links that address this in greater detail; the link to the What’s Best forum includes posts by Jonathan Carr, a noted designer of LOMC cartridges. The one to Jim Hagerman’s website has some of the math and some charts that show whats going on:
http://www.hagtech.com/loading.html
https://www.whatsbestforum.com/threads/cartridge-loading-a-misnomer.15077/
I read both links. The first is common knowledge and nothing about RF. The second is long so if there is something in particular you want to me to read please quote it here. Are we playing "Wack A Mole' here? Im really tired of RF being the devil for everything. Usually if there is RF sensitivity you will hear an AM radio station. If there aint no radio coming in there aint no RF. Lets get real please. |
Power is equal to volts times amps and is also equal (thru Ohm's Law) to current (squared) times Ohms.
In this case, to make 100 watts into 8 ohms, you divide 100 by 8 and take the square root, which is about 3.4 amps. That's all thats needed to make 100 watts if the load is 8 ohms and it makes no difference what kind of amplifier it is. So what is the 29 amps??
HI, I was involved in that discussion about the Benchmark amp. Some of us were trying, without much luck, to advise the owner not to bridge the amps into his speakers. Then we got into current. Then the whole thing fell apart and I left. To answer your question. 100 watts at 8 ohms is 40 volts peak. If you have an electrostatic or other speaker that goes down to an ohm or two you will need a lot of current to play trumpet music at full level. You may need 40 amps to get your 40 volts at 90 degree phase and most amps will be very unhappy. The Beveridge ESL required 1500 VA to play Miles. There was no way to get that through a reasonable transformer so we made Direct Drive 3000 volt amplifiers that provided 1/2 amp of current. |
@krelldreams
I’d like to add this: I appreciate the fact that there are two professionals contributing here, despite the fact that there is tension that’s been created by disagreement. I’m trying to read through the commentary to the points being made, the examples being given, and the facts. The reality is, there are many ways to arrive at the same destination. I’ve listened to, and owned A LOT of gear in my life, though none, so far, by either of these designers. Some products allow the music to communicate to you, some don’t, and a combination of components may speak to me, but not to you. I know this isn’t a technical question, but I felt compelled to write it nevertheless.
I appreciate your balanced view on two designers, with very different viewpoints, airing their design thoughts in public. Im fine with it and I hope readers understand that sometimes a statement is so shocking to me that I get a little worked up about it. I have experienced and previously stated where cartridge loading makes large difference. I love to do things on the fly with minimum time between evaluations. Therefore I built a 6 position load box for my Denon 103 from 10 to 200 ohms, including no load. I can just dial through and listen. The Denon is a cartridge that needs loading otherwise it is bright and harsh. Around 100 ohms it sounds good to me. Below that it gets kinda dead sounding. On the other hand we did the same with the Lyra and no load sounded the best. We had a switch of 12 loads from 3 ohms to no load. From 10 ohms up we heard no difference. The audience was 40 people who generally agreed and were surprised at what they heard. I fully agree and have stated before that each of us have a system that is "his sound". It can be fun to visit and listen to others sound. Now what does one do when (and this is a horribly delicate situation which I have encountered too many times) one visits a friend and while the owner thinks things are fine the system is actually broken. When I found the bad 6SN7 in the Oppo the owner said it had probably been like that for a month. When we find a speaker out of phase it might have been that way for half a year. When I hear a distorted amplifier and I put it on the bench and find it way out of spec what has the listener been doing? I visited another audiophile who had $100,000 of good gear in a cubic room about 14x14x14 feet with all hard surfaces and no treatment at all. The room was so live I couldn't even carry on a conversation. I politely said.. "Hey its nice outside can we go sit in the sun and chat" When we came back in to listen he asked me what I though of his system. I told him, Sorry I cant hear the system I can only hear the room. Once again he though because he had good equipment that it had to sound good. Of course we should trust our ears but where is our reference? How many high end systems are being listened to with something out of wack. I am likely one of a very few designers that actually will repair others equipment. I do this because I like to see others work, how they make things, how their things perform. I have tested over 400 amps and preamps and can tell you all about what is going on in them. |
@fsonicsmith
I think you are mistaken. I don't recall ever entering into any debate of any kind let alone some type of trolling-skirmish with you. IMO, you are once again confused.
Let me ask you this Roger; other than one of Ralph's amps, which modern era top-tier tube amps have you actually sat down and listened to with not just your own planar speakers, but also modern coned speakers across a decent spectrum? I ask because as I have said previously in this thread, you keep referencing ancient amplifiers of the remote past which you conveniently choose to piss all over. Others have asked you this same question too and you have not responded. Are you living in a cave?
I re-entered because I could not resist. I saw that your irascible behavior has continued and not just towards me, so I felt better about re-entering. I do respect you and your knowledge base, but it also pays to be a gentleman. Towards the end of his life, Charley Hansen (you misspelled his name a few posts ago-shame on you) was very vocal about MQA and his debate with JA on another forum became quite heated. Throughout that give and take, both managed to remain polite and civil. You could take a lesson from them.
I brought up Charley Hansen's interview towards the end of his life about his latest iteration of amps finally-in his opinion-capturing the sound of the best modern tube amps. Have you sat down to listen to any of his amps? Have you analyzed why they might sound as they do from an engineering standpoint?
I am into vinyl, thank you. I am the proud owner of a Manley Steelhead, which I bought new. I love it and love Manley. I wish the aesthetics of their amps suited me more. I acknowledge that letting aesthetics get in the way of a purchase decision seems silly. I also acknowledge that Ralph's views on cartridge loading differ from my own. But as you quoted me (accurately), I have 1% of your engineering knowledge and his too. But I have years and years of empirical experience and based upon that, I have chosen to disregard Ralph's views on cartridge loading as simply not applicable to my particular system and experience.
Perhaps I have mistaken you for someone, however your last post was rather heavy handed. But lets shake hands and move on. I hope to be brief because this is not on topic. I do not think I have ever mentioned Charley Hansen in any post. Please correct me if I am wrong. I would like to read an interview that you particularly like, could you please provide a link? He made excellent equipment and I can see from JAs measurements he did a good job on the three major characteristics of a good amplifier, one that would drive a wide variety of speakers well. On this I am in complete agreement with Charley. Im not sure why I need to listen to his amps, I am confident they sound find. Charley and I are on the same page with what is important. Though some may take objection to the following here is what I have found: If you compare several amplifiers that meet the three criterion of damping, low distortion, good current delivery then these are what I call good amplifiers. Good performing amplifiers tend to sound very similar because they are GOOD. Now if we take one of those ampifiers and compare it to amplifiers that do not meet the three criterion (there are more than 3 but the first 3 are the most obvious) in an A/B setup, levels matched, the differences can be quite alarming and immediately obvious on either pink noise or the proper choice of source material. This has been my experience over 45 years of doing this. I invite others to get their opinion. I invite you to come listen, bring any amp you like and lets have a go at it. In the current setup I am using QUAD 57s and a few cone speakers. I prefer ESLs and find them more revealing. I think everyone knows I moved to Santa Barbara from VIrginia specificaly to work with Harold Beveridge in 1978. As I recall he paid me $500 a month plus royalties on my preamp. I didnt do it for the money I did it to apprentice to a master. In the past year I have repaired and listened to a Reference Line SS amp, A big 833 SE amp. Several Single ended 45, 2A3, 300B. Of course I listen to all of mine and aways to the strict A/B. As to modern amps, on some we are going backwards. The Cary SLI 150 is an example. While it measured badly it sounded fine to Herb because he played it at the low range of power where the distortion is low. This is a very common occurance at Stereophile. Once a broken EAR amp got a great sonic review and upon test it was discovered to be very distorted about a few watts. However below that level where the reviewer used it there was no appreciable distortion. It is clear to me that most reviewers do not put a high power amp through its paces. Its just not how they listen. These days anyone who can get an amp to work at all and has the ability to get it to market ends up doing so. Eveanna Manley is a close friend, I have stayed at her home when David was still around. I have sold them EI EL84s. I know the stingray well from the point of supplying tubes. The bias control range is rather narrow, Have you had any trouble getting tubes that will not bias up in the range of the pot? We had do do selecting for some customers. |
@fsonicsmith Ralph-you should never have entered this thread. You tried to kill the OP with kindness and camaraderie, and he spit on you every chance he got. I think most of us reading through this thread can see the OP for what he is; entrenched in the remote past and bitter. His hubris is out of bounds. I have been around long enough to suspect that there must be something else going on in the OP’s life that is causing him to behave so poorly. As Oldtech noted, this is my thread. Hi, fsonicsmith., you seem to troll my threads, this is not the first time I have encountered you. Aren’t you the one who said you knew only 1% of what designers know. I was looking for that one.. It appears a lot of your responses are now missing. Ralph has not honored the stated purpose and rather come here to once again to hawk his paradigms and unusual ideas about cartridge loading and RFI. You are into vinyl I see. Do you agree with his loading suggestons? Dont we load a cartridge to change its sound? That last one about loading a cartridge for the sake of the preamp was so out of the world. Most of just a juse a ferrite bead to stop RF from coming in. I was happy to discuss his points till it got out of hand. Ralph can run his own thread if he wants to promote his paradigms. You write well, perhaps you could edit the one on Power so it makes some sense. I do agree, Ralph should have never entered this thread nor should you. I dont see a question and I dont see a contribution. You left, said you wouldnt come back, but you did. I dont mind any designer coming here if we both understand electrical science in its accepted current form and speak the proper language. If you want to read made up science there are pleanty of other threads on here for that. I have a a question for Ralph, Why have you not sent an amplifier to Stereophile for review? They have reviewed all of mine and preamps too. |
@krelldreams What prompted my question regarding tube types was the discussion in this thread about 6sn7/12au7/6sl7/5751/12ax7 tube type use for preamps and amp inputs. But there is also the question of power output tube choices - el34/6550/kt88/kt120/kt150, etc. It appears that some designers use the same tube types in their products, however there are instances where designers switch types year to year, or even have concurrent products performing the same function (amp or preamp) but using different tubes. Consumers and reviewers, also, sometimes prefer only 6sn7 or 12au7 based preamps, or kt120 or el34 amps, for example. I was hoping to get the viewpoint of someone who makes this choice. Thanks for an on point question. For years Everything ARC made used 6550s. Some makers are similarly fond of EL-34s. Some consumers are in love with that little 9 pin EL84. Part of the tube choice is driven by, you, the consumer. I built an EL84 amp because I know there a lot of people who love that tube. I did do someting different and got 35 watts per pair rather than 17 watts. I raised the power, kept the safety and life of the tube and made somethig to this day people do not believe possible. The application is laid out in my 2018 Burning Amp presentation. On the other hand I built the RM-9 to take any octal power tube, of which there are many. Power stays the same, only the negative bias changes. I did this so that users could compare widely different power tubes on the same platform. In my thinking how can someone say something general about a particular power tube when they are comparing it in two different amps? David Manley got very upset over the RM-9 and we exchanged several letters in pubic in the Stereophile. They are fondly known as the Manley/Modjeski letters. I hope to get them up on the HIFI school site. At the same time we coined the term "Tube Rolling" and I made buttons imprinted "Member, Nimble Tube Roller Society" This was way back in 1983 so young folks may have missed it. David was totally opposed to tube rolling. You can take an old RM-9 and use 4 of the KT 120s or 150s instead of 8 of the earlier tubes. Will still produce full power with half as many tubes. What I see in the market place now is that New Sensor (Tungsol) is creating larger power tubes and there are those designers who appear to get out a new amp with the new tube as fast as they can, which does worry a bit. If a designer goes for the full power of a KT-150 and you have to go back to the 120 or 88 you will loose power. If the Russians do something bad the KT 120 and 150 could disappear until someone else takes it up. You can add your own "ifs" to the list. HP and other equipment makers had a policy any part had to have at least one other supplier. Single source parts not allowed. Tube cost is another criterion. EL84s are very inexpensive, EL 34s next. then 6550/KT88, KT 120s. However the KT150 cost to me is about twice the KT 120. The look and power are quite a departure and I will not be surprised it the next bigger KT is already in the works. KT, stands for Kinkless Tetrode in the UK. We use Beam Power Tube in the USA for the 6550 which is essentially the same thing. The first beam tube was the 6L6, a great tube that no one uses because the public has someting against it, for no good reason. In essence, You, the buyer are controlling the tube choice as much or more than the designer. Hope you choose well. :) |
@fsonicsmith
not all things that matter are amenable to testing.
Indeed we cant test for everything. However we can test for the big three and include that information in our listening. For instance if one amplifier produces a lot more bass from a speaker which amp is right. If the person prefers more bass then he buys that one. However usually when there is more bass the bass is not as good. Its uneven, boomy, the extreme being the "one note" bass. Now if we measure the amp with more bass and find it has poor damping we can say to the first order that is due to the poor damping. What gets interesting is when we have two very good measuring amps that sound fairly alike and one is tube and one is SS then we have to start wondering as Charlie did, What is it tubes do differently? I hope someday I make a better amp than what i have made so far. An RM-9 is hard to beat. So are all the Marantz tube amps. Perhaps I have equaled the Marantz 8B, Saul's favorite. Perhaps I have better bass because now we have much larger filter caps than he had. Other than that not much has changed. BTW Saul told me that around the shop they firmly preferred a pair of Mono 8s to the famous Model 9. |
@ptss
@ OP. How do you feel about Spectral Audio designing amps with extreme bandwidth? Are there benefits for solid state amps?
When I went to Vegas in 1978 Spectral was playing B&W video through their line stage. The volume control thus because the contrast control which they encouraged everyone to play with. The picture was ok so it was at least a few MHz of bandwidth. I guess they liked bandwith. Their designs were, in my opinion, excellent.
I dont see how it makes a difference to go that far and it is an invitation for RFI to be passed on to the power amp.
After a certain point slew rate and bandwidth are just for bragging rights.
In output transformer tube amps wide bandwidth, maintaining stability and getting the big 3 parameters reasonable, is the greatest challenge |
Hi to all.
Perhaps I was not clear in my original posting that this is a thread to ask the OP a question and have it answered by the OP. It was not an open invitation for other designers to answer questions or give their opinions on my answers. The whole point is to give the public some insight on how I design things and how I evaluate my own and other equipment.
If you notice John Atkinson and I have similar views on what an amplifier ought to do.
If other designers want to have such a thread all the better. I would not care to comment on their thread because those are their answers, their views.
In the end I hope to educate. As far as selling anything I am happy to share the workings of my A/B test set up for no charge or build one for someone if they want to get into A/B testing.
I am most happy to discuss interactions in equipment, how I go about designing, how I listen. Far down the list is the sound of particular tubes or brands of the same tube. I will talk about what different tubes can and cannot do well. I can talk about how some circuits are more sensitive to tube rolling and some are much less so.
Now can we please proceed with this in mind.
|
I made a few Zero Feedback amps in the 1970s, Still have one, perhaps I should dust it off and have a listen. Like Charlie I maintained the big 3 targets. If you don't you will have created an amplifier that is very speaker dependent. |
@krelldreams
You mentioned, that in the RM 9, two KT120 or KT150 output tubes could be substituted for four EL34s in each channel. Is there an advantage to using fewer higher output tubes as opposed to using double the number of lower output power tubes, or vice versa? In other words, is the former following a “simpler” path than the latter?
The advantage lies in fewer tubes to fool with, a little less heater draw so the power transformer will run cooler and you get away from the tight matching of 4 tubes. The path is the same. The idle current will be the same. Might have to shift the bias a little. I know the 120s work. We have had several people do it. If I get a chance I will give the 150s a try in an RM-9. Might look cool having 4 x 150s in the front row. |
@bdp24
I have for years heard accusations from audiophiles about TAS and now Stereophile requiring advertising from any company wanting one of their products reviewed. I have never seen any proof of that, and have to point of that though I have never seen an ad from Music Reference in Stereophile, a review of the RM-200 by Michael Fremer has twice appeared in the mag; once of the original version, a second of the Mk.2. That the Arma-Sphere M60 and/or MP-3 have not been reviewed is ridiculous. They review all kinds of over-priced status symbols, why not some high-value mid-priced pieces (the stuff most of us are interested in owning)?
True, I have never advertised in Stereophile. I run a different ship than most. I was offered to share the front cover for the Fremer review but declined. I want my amps to sell on their merit not advertising. The people who know will find me, its never been a problem. I find Stereophile and JA the most unbiased folks in the industry. TAS is and always has been a joke technically. Harry made the best of it as the self acclaimed "Audio Pusher". I read a few issues over the summer and saw that their current model is the "two page review" Every review was two facing pages. How boring. Where do the reviewers find all those words? TAS will never measure anything and what am I supposed to learn from all those words. Stereophile also reviewed the RM-5 and RM-9 in the 80s. Im quite sad where things have gone in this industry I have devoted my life to. Need I say more? |
@almarg
That’s interesting to hear, Roger. Although to be precise I’m pretty certain that the 8 and 8B were both single-chassis stereo amps.
I’ve never heard an 8 or 8B but during the 1990s I owned a pair of Model 9 monoblocks and a pair of Model 2 monoblocks. And I greatly preferred the sound of the 2s to the 9s, although in fairness I can’t exclude the possibility that condition may have been a factor in that.
The 2 was similar in some respects to the 8 and 8B, which came later of course. Although in addition to being monoblocks the 2 employed tube rectification, while the 8 and 8B used solid state rectification, and the 2 used 12AX7 input tubes while the others used 6BH6s.
I’ve commented here in the past that at least when used in conjunction with speakers having benign impedance characteristics and not requiring more than the 18 or 20 watts or so that the 2s were capable of in triode mode, in that mode the 2s were one of the best sounding amps I’ve ever heard.
I never got my hands on a 2 but I studied the 5 (half of an 8) in great detail and I saw how they did the tertiary feedback winding. I had to do a lot of experimenting to make that work out but its a trick I have rarely seen in other amplifiers. The separate feedback winding makes the amp more stable into reactive loads. Perhaps few know that we made all the transformers for the RM-9. I cut my teeth on the design of that output transformer. The 9 was quite a departure from the 8, far more complex, perhaps better specs, but when you take specs too seriously (as in too much feedback) things can go downhill. |
@bdp24
I also remember The RM-5 and the Audible Illusions Modulus 2 were considered THE bargain tube pre-amps to choose between. I found the AI Mod's 30dB of line stage gain unfortunate and ill-advised, as well as it's dual-mono volume controls. The Modulus is still in production (in updated form, of course), so Roger, any thoughts of offering a contemporary RM-5 type pre?
Thanks for the memories... who sung that? The Modulus and RM-5 present a great example of dueling designers. Art did not put feedback around the line tube as I did. I also made it variable with dip switches for many gain settings from 0 to 30 dB which is the full gain of the tube. He later put a cathode bypass disconnect to lower the gain but that is a Very bad idea as it raises the output impedance to about 10K. The feedback in my line stage lowered the output impedance to about 1K. Im surprised people didnt hear the difference more easily. Again, that would have showed up in an A/B which is just not done is it? Where I did volume and balance Arthur liked his dual controls. Other than that the preamps were pretty except for the power supply. His blew up, mind didnt. Problem was, Arthur was not an engineer and the preamp was the work of many people. I think he bought the company from Bruce Moore. Hope Im not bragging on mine too much, just the facts Madam. He claims in the TAS book to have sold 25,000 units. His tech, Meserve. was my tech in the 1980s and said theres no way. We sold 960 over the 15 years we made it. All sonically and ciruits wise the same.. Only thing that changed was the jacks as better ones came alone. If you can find a MKIV that was the nicest as we put on a phono tube off switch, heavier metal, nicer jacks. We only made 50 so good luck. The MKIII is more available and just as good except for those two things. |
@krelldreams
I do have technical questions regarding cabling and AC outlet use though! I’m not excited about super expensive cables (I’ve tried many with very little in the way of difference), but there are electrical differences (capacitance, inductance) in wire. Also, there are different metals and connectors used. What should one look for in terms of material (copper, silver, etc), and electrical properties (capacitance, etc) when choosing wire?
Regarding AC outlet use, how does one best work out the unavoidable need to plug various components into a two outlet wall plate? I had an electrician run a dedicated 30A, 10AWG line to the duplex behind my system location to isolate the stereo components, and to provide enough amperage for the amplifier’s initial turn on draw (it was tripping the 20A breaker). I have seven components that need power. I plug my power amp into one of the outlets, and a “high end” six outlet power bar to the other outlet. Is there something special, and necessary about power strips for stereo components? If so, what does one look for when choosing between them?
Not sure what I can do about the passive thing but you can write Tony at tubeaudiostore@gmail and he will forward to me.
The capacitance and inductance in a power cord is vanishingly small and can be ignored. Some platings are nice. DeOxit is a good cleaner and cleaning may help more than anything. I would have had the electrician put in several duplex outlets so no power strip is needed. Power strips vary in cost and quality but the expensive ones with big claims are just marketing. You have nice 10 Ga wire in the wall and then what? Heres something Ive done. Get a bunch of reasonable power cords, like $20 each of various lengths. Cut off all the male plugs strip and hardwire the cut end directly to the 10 GA wire with a bussbar. Solder good solder lugs to the wires and screw them with a star washer to the bussbar. THe star washers are important. Now you have direct power cords and have eliminated one connection. Make some extras of course.
The ones you arent using just coil them up.
I had custom power cords made that are 8 ft long, very flexible, supple, drape nicely and wont pull your smaller devices off the shelf. We have them if you need some. Bottom line here. Its not the wire that matters. You have hundreds of feet of ordinary magnet wire in every transformer. What you gonna do bout that? :). All this power cord and power strip is just foolishness. Why do we need powercords that are a pain to run? Thanks for the question. I hope people can see that throwing dollars at something is not always the best solution. |
@stargazer3
OP do you believe in the burn in process of an amp that over time the sound will settle and finally focus on a cohesive musical experience or is it to your opinion all in our brain that is adjusting to the sound of the component? When I mention burn in process its regard to periods of 300hrs and more (eg Naim or Simaudio Moon amps).
Speakers for sure. The are mechanical devices that have to loosen up. I hook up my woofers and drive them hard for a few days and can measure the resonant frequency drop a few Hz. Amplifiers, only the tubes. When it comes to electronics and wire I believe the listener is becoming accustomed to the change. For those who will likely disagree: If burn in exists in these devices why did we not know about it until recently. I find no references to burn in in the 50s 60s 70s.. when did it start? I know the manufacturers love the idea because it gives them a reason for you to get used to the product. They are certainly going to promote the idea. With digital devics I really have to wonder what is burning in. The digits? We always burn in amplifiers to find infant mortality. We would rather have an amplifier break in our shop than in your home. This process is well documented and 24 hours usually does the trick. The failures are very rare and most often just a tube. We even cycle the amps on and off many times to temperature cycle the glass which is what usually fails but its just 1 out of 100 tubes. With tubes I always set the idle current (bias) 10 % low because I know it will come up a little in the first 100 hours. |
@ieales
minimize artifacts occurring from the interconnect cable between the preamp and amp.
A second reason is that a preamp can provide a fairly high impedance load for the source Source output 22R, amp inputs 23k5 or 100K. Adding a preamp with attendant switching, circuitry, noise and additional cables is little more than a subtle tone control. It maybe different, but it may not be better.
I agree with ieales and not the answer given above his, but then you all know that. What are these artifacts, are they Egyptian? |
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@bdp24
@ramtubes, Here's a question for you Roger regarding a matter that was being discussed amongst Maggie owners on The Planar Speaker Asylum forum yesterday. One poster said of hearing from tube amps something I too hear, and that is of a sound stage that begins in front of the loudspeakers. I heard that for the first time when Bill Johnson played an LP of Holst's The Planets (in 1973 at Audio Arts in Livermore, after he finished setting up his complete system in the shops really good room), a recording made in a large hall. The front of the orchestra was clearly located between myself and the front plane of the Magneplanar Tympani T-I's, and the rear of the orchestra was waaay back behind the speakers, sounding as if it was actually further away than was the wall behind the Maggies. I could hear the delicate triangle in the rhythm section, elevated on risers, playing in the quieter sections of the piece. It was thrilling! Prior to that experience, at Sound Systems in Palo Alto I had heard a pair of the original Infinity Servo-Static ESL's, powered by the then-new line of SAE electronics. Through that system I did NOT hear the image "thrown" forward of the speakers. I have subsequently heard the forward image (and great depth) from other systems (including my own), but only when the electronics are tubed. So my question is, why is it tubes are able to do that? Is it a matter of tubes being lowest in distortion at lower-signal levels (where imaging resides?), and transistors in their curves highest?
Thanks for throwing the ball my way. I would like to say its a property of tubes but I rather think its a property of how well the system was set up. I dont feel ampifiers have much to do with imaging. I don't see how they can. However I think they sound better than SS and therefore the system sounds better. When the system sounds better all sorts of nice things happen. If you want to hear great imaging like you have never heard before find someone with properly set up Beveridge ESLs., the Direct Drive ones. They have 180 degree dispersion at all frequencies and properly set up FACE each other sending sound directly to you, directly to the middle and directly to the back wall which must be at least 6 feet away. Not many rooms will allow these set up distances. Ideally the room is 11 ft wide and 24 feet long or longer. Then the back of the sound stage is 2x6 feet or 12 feet deep. Its really cool. |
@krelldreams My verdict, with this passive unit, in my system is as follows: The system with the passive has clear high and mid frequencies, good space, and sounds spacious... but it is a bit brighter, a bit leaner, and is less pleasant to listen to than with the preamp. I’d call the sound with the preamp “smoother” and “warmer”. The vocals through the preamp were slightly veiled compared to the passive though, which annoyed me. So.. after this exercise, I believe that either a better quality passive, or a more transparent preamp, is what I’d want. What design elements could improve the sound of a passive device? Clio wrote about a phono preamp with passive level control and aux inputs. What a great idea! We make those phono preamps with a aux for people who appreciate that kind of thing. One other advantage is that you only power the phono section when you need it. Otherwise it is completely off, thus saving the tube life. From a pure business sense I should talk preamp up and passives down, however that is not my truth. Passives are a great solution when used properly which is: dont load them with a lot of cable and dont load the source. This is easy today with low impedance sources. Of course an active preamp is going to add a little distortion. Typically you can count on about 0.1 % per volt of output if there is no feedback. We dont know how every preamp colors the sound because we dont know what the designer is doing inside, perhaps intentionally. Some designers cheat the game by intentionally making something colored. They know someone will love it. Dont go assuming all preamps are designed on a level playing field, especially these days. As someone said here he likes the microphonics of his 6SN7 preamp and calls it euphonic. Microphonics can pay a large role in preamp sound. Go tap on some tube preamps and see what comes out. The thing that intersts me is that most complain that the bass of passives is usually lacking. However the bass of passives goes to DC with no phase shift. Tube preamps do not go to DC and at 40 Hz will start to have some phase shift. Is the phase shift what they like? |
@twoleftears
Technical question: Do certain electronic components, e.g. capacitors, need to "form" before they operate at their best?
Electrolytic caps do need to form and the form time is related to how long they have been off or stored. This is why smart tech bring up old equipment on a variac, to let the caps form. If power caps are just hit with full voltage they will draw DC leakage current as they form. If they get too hot in the process they explode. The process is regenerative so it goes very fast at the end. Many people destroy otherwise good caps by just turning things on for too long. If people want to know there is a lot to be said about these caps and I have studied them in depth. I made a current limited "former" that will prevent the overheating runaway. Sometimes old caps are better than what is being made now. I know because Ive tested them. It takes about a day to fully form a 10 year old cap. They often form to much higher voltage than the rating. The old man at Mallory explained it all to me. In large quantities where we spec what we want, the voltage written on the cap is more often the voltage on the purchase order rather than what the cap was made for. For example we ordered 1000 pcs of 150 uf 315 volt caps at Beveridge. I tested them and found them good to over 500 volts, therefore I would say they could have been marked 450 but we ordered 315V. We got more than we paid for, but one has to TEST these things to know. He also told me that stored at cool temperatures 10 years takes only a month off the life of a cap. Basically nothing. Its all about the water inside staying inside. I am sad to report that modern caps from good makers are having other problems that prevent this kind of testing. Recently I found some good caps flashed over at slightly above rating because the edge margins on the paper had been reduced to shrink the cap's size. Now that is sad. My advice, heed this well, If you have old lytics that are working fine, DO NOT REPLACE THEM. The new ones may not last nearly as long. I have 30 year old caps in RM-9s that are doing just fine. I don't think modern caps are going to last 30 years. Oh, perhaps I forgot to mention, Im really into finding out why parts fail. One has to care to make long lasting equipment. |
@grannyring
I have a technical question regarding a PP EL86 tube amp I am modifying. I would like to upgrade the power supply. The current power supply is very, very simple and while simplicity is good I think a more robust supply could help sound quality.
A couple of questions and these should also have application for many others here.
1) All filaments are AC heated! Not DC. No filtering, no rectifier....Love you hear your comments on this. Would converting to a CLC filter with possible voltage regulation be worth doing?
2) 5U4 rectifier Tube receives 350 VAC and post tube VDC of 476 with no load. The plate supply is a simple RC only. 100 ohm resistor followed by two 680uf electrolytic caps in series. This feeds the vintage Scott output trannys. If I wanted to add a choke where should it be placed and how do I determine the value correctly. Like to know how you would design the plate supply for this simple PP el84 amp.
I ask your opinion of SS voltage regulation on both filament and plate supplies. Is it something you regard as very important?
EL 86 is an interesting tube. I think of it as an EL84 with half the screen voltage so Ultralinear is generally out. What is the circuit like? Most people dont realize the screen supply is more important than the plate for hum. So how are the screens connected? No need to DC heat power tube filaments, better not to. If you have hum in the front end DC heaters may fix that. The 5U4 is a good rectifier but does have a larger voltage drop than a cathode tube like a 5AR4. They put the 100 ohm resistor to reduce the plate peak current. Even a 5AR4 doesnt like to see more than 40 uF. All that information is on the data sheet. Tube rectifiers were useful in their day, I see no need for them now. As to filtering, you really have only one cap and thus a fair amount of ripple. C L C filtering is the best and make the last C large so the bass can draw on it and not sag. There are lots of power supply emulator programs out there. Duncan Amps has a nice one. Regulation for filaments is easy so use a 3 terminal regulator for that. B+ regulation is difficult. Dont try to do too much too soon in the learning process. |
@bdp24 The old Polk Audio Cobra cables were a very high capacitance design, and caused some amps to become unstable . We briefly sold those cables till we found out if you step on them they short out. Weaving magnet wire into a snake skin is a really bad idea. |
@ieales
More than once I've rejuvenated a system by re-plugging ALL connectors, both internal and external. YES, YES, YES. Ive fixed so many things just doing that. Flat screen TVs, my Sony ES player many times, Its used up 6 of its 9 lives. Its sad how many components, expecially CD players end up on the scrap heap that could be fixed in 10 minutes. Dont forget the ribbon running to the laser head. That one needs the most attention. Use some logic. If the player cant read a CD go for that one. If some of the display is out or buttons dont work go for the one going to the front panel. Its really simple and you have nothing to lose. CD players cannot shock you. Do unplug them however. (I dont). When I open a unit with lots of those ribbon connectors inside I know it has limited life. All connectors oxidize. Oxides also form rectifiers in the signal chain and distortion. |
@stargazer
I must admit that I personally in my limited experience of owning new HiFi components I never experienced this marked change of sound during 'burn in process'. When you confirm that in regard solid state amplifiers it is the listener who is becoming accustomed to the change thats quite an assertion when you consider the host of people (professional and non professional) who claim to have actually heard and experienced the change of sound during the claimed burn in process. Its fascinating that such a divide exists among normal music lovers.
It is quite an assertion that I made. We know not what they heard, we know not what posessed them to make such claims. I assert that the change is so subtle as to be entirely imaginary. I have said to many who report such " Wow you have a really good imagination"
Look at it this way. There are professionals and non professionals who assert they have golden ears and they must say these things to support their ears. We dont know what someone is hearing.
As I have posted previously ive been in a room with some golden ears where the system was "broken" and they didnt hear it. Given that who is really hearing what? |
@prof
And if burn in occurs in cabling, why don’t we see people producing these measurable results between a new and burned in cable? The suspicious thing is that when most cable manufacturers are hyping either the technical reasons why their cables produce better sound, or telling you the cables need burn in, they are always appealing to some objective, technical phenomena whose existence is known because it was measurable. "Here’s a technical problem with cables you need to know about, that we have solved via our manufacturing process!" Nicely done all of it. To the part quoted the reason we dont see measurable changes is that there arent any. Of course the people who believe in burn in and such will just go to the default "well you cant measure everything". If you measure the things we can measure they will stay the same. We all need decent cables, thats fine. Decent cables need not cost much and are very easy to make. Up until Monster came on the scene most people made their own speaker cables out of zip cord, which is an excellent choice, very low capacitance, resistance as low as you want just buy more copper. High capacitance speakers have been known to blow up SS amps as they cause the amplifier to go into oscillation. Ive seen a Levinson smoke. |
@jlhaudio
Roger, why did you switch the input to the 12AT7 from the 12AX7 on the Ram10 mkll?
Along with changing the bias system from fixed to cathode bias and changing the B+ I found the 12AT7 was a better choice. It has a lower saturation voltage than a 12AX7 and higher current. As far as we can determine the amps sound the same. We want them to. |
@atmasphere
If the capacitance of a cable causes rolloff, is that an artifact? |
@atmasphere
Our MP-3 preamp is based on the first balanced preamp circuit ever sold to high end audio (our MP-1). It has a direct-coupled output (despite being a tube preamp) and has bandwidth to about 400KHz.
Hum, This is a bit self promoting of a current product. I will quote two products no longer made that were years before the MP-3. David Manley had a balanced phono input (which is always going to have 3 DB more noise than unbalanced as it uses two input devices) It is also not necessary as the cartridge is a foating source. The RM-1 had Direct coupled output in 1978 and is lower noise than the MP-3. I have measured both. Clio was there for there and took notes. Did you fix that RIAA yet? |
@fleschler
EAR 912 with tubes rated for 100,000 hours and non-microphonic.
I have looked at the rating of many tubes, last I looked Tim was using 7DJ8s. Those are 10,000 hour tubes If you get 10,000 be happy. Most tubes are rated for 10,000 hours and 10,000 turn-ons .So watch that. |
@grgr4blu
I have enjoyed posts by Ralph and Ramtubes on this forum. They are both highly qualified as designers and manufacturers. They both provide answers to technical questions about gear. Sometimes, they include opinions based on their understanding of the science behind gear. Nevertheless, their posts are almost always informative to the membership here. Occasionally, they are self referential, although I do not view their contributions as self promotion that should be banned such as posts by Audiotroy which usually contain rank self promotion and, at other times, stealth promotion under the guise of informing the Audiogon community of his opinion ( almost always favoring the gear he sells) based upon his vast experience which he claims is more valuable than the opinions of other dealers who are out for the money--- while he is out to help the Audiogon community. Of course, these are extreme comparisons about what should and should not be permitted here. I suspect the line should be drawn somewhere in between the services provided by Ralph and Ramtubes and the disservice provided by Audiotroy. Might I add that Ralph and Ramtubes are not close to that line IMHO.
I toatlly agree about not promoting ones product and plan to watch it carefully. I would like to see people make some simple A/B boxes and will tell them how for no charge. If I make one for someblody its a one off and not a product, just a tool, and a very good one. Perhaps I can make one and we can pass it around to those really interested and can convince me they can properly perform the experiment. I will remind everyone that this thread is to answer and discuss technical topics. If you want me to answer personally pease direct the question to me. Furthermore If anyone wants to debate a topic, be sure to have vetted sources to support your premise or be good at supporting it yourself. We have had a few on here that went on an on with no support, clairty or sensiblity. |
@atmasphere
But here's the kicker: This thread was put up as a promotional device. You can tell because the manufacturer is talking about his products, often more than once in many of his posts. This is against the Audiogon rules, but because I and others are posting here as well, the entire thread doesn't have to be taken down.
I notice on this account that Georgehifi isn't being taken to task; although while he is a manufacturer, he's not an amp designer. But this thread has drifted to the topic of preamps on occasion and on that account he's been posting too.
Ralph, Im sad to have to say all this but you have a very different about the owner ship of threads on Audiogon. of course it is a public forum, however it appears that most threads respect the OP as the moderator of his thread. I think the original post is pretty clear. I am here to answer questions, educate and share the results of my experiments that I encourage others to have a go at some experiment that they may find very enlightening. I never imagined other amplifier designers would want to answer questions directed to me. If you think one of my answers is wrong you are wellcome to chime in but not with your paradigm or unsupported theories. I dont welcome any unsupported theories, poorly vetter answers from flawed articles. Perhaps its time for you to start you own similar thread, Anyone who wants to ask Ralph a question can easily find him. You have a paradigm to promote with which I totally disagree. When I bring up that a widely varying impedance speaker will not sound as the designer intended, you bring your paradigm.. Perhaps your amp provides a tone control some like. I have 2 m-60s in my shop right now in my A/B test rack, anyone is welcome to come listen. One is stock one is my mod with feedback. It appears you have abandoned feeback on some psychological level rather than listening. We are just listening. So please dont bring your, not vettet, paradigm to a scientific discusstion which is in general disagreement with it. That is self promoting to a high degree. Why post here when you have known for years we disagree about damping, distortion, current, tube applications and a host of other things? Ive read your paper over and over again and it makes little sense. You are the only outside designer who has entered this thread. When you answer questions from your point of view I have to deal with that and it makes more work for me. We already know what you are going to say you have said it 6,798 times. |
@pwhinson
I used to think that power was power with only minor differences in the sound. However in trying to decide on the best amplifier for my Thiel 2.4s I've auditioned the Bel Canto m600s (their current production monblock), the Bryston 4 cubed stereo amp, and the Pass x150.8. They were PROFOUNDLY different. The Bel Canto rather oddly was very recessed the dark sounding, the Bryston was a little shrill with very little mid range "meat" on the bones but the Pass was JUST RIGHT. Honestly, I'm being a little sarcastic here but these were not subtle differences. I left the experience feeling that the "electrical" handshake between the power amp and the speaker is considerably more complicated than I originally imagined. Thoughts?
Those are all big amplifiers. Given the low impedance in Thiels you want the amp with the most current. I would only listen to one amp at a time with one as a referene in a strict A/B test. Swapping amps has to much time between, levels are often not matched. I wish dealers had A/B boxes but its a lot of work and they dont want that kind of testing. You may find out the less expensive amp sounds the same or better. When you compare good amps with good specks they really cant sound much different, can they? Now throw in a high distortion, low damping amp and you will hear that. |
I want to end this amplifier pissing contest. This is not the purpose of this thread. If someone wants to make amplifiers out of the accepted normal standards why would he be coming here? We are discussing normal amplifiers not outliers. 99% of speakers are designed and voiced with low output impedance (high damping voltage source) amplifiers. If it were designed any other way the maker and owner would limit be limited to the amplifier the speaker guy used. Modern amps starting with Fisher, Marantz, Eico, Heath, Williamson, have damping 10 or above. That was one of Williamson's specs along with low distortion and wide bandwidth. Williamson set the bar and all reasonable amplifiers have respected this bar because it works and sounds good. One can make amplifiers out of these standards but they will not play speakers in the way they were intended by the speaker maker. They will change the tone of the speaker to the extent that they interact. Most reviewers are using high damping amplifiers (except when a low damping comes along). Most of the world is using high damping amplifiers. John Atkinson shows you what happens to the frequency response of the amplifier he is testing when connected to a typical speaker. If the damping is low it is not pretty. You will hear the modification of the frequency response which you might like or not. You definitely will hear the one note bass at speaker resonance. Two notes for a ported cabinet.
Speaker makers count on you having low output impedance as they did. Remember a damping factor of 10 is generally enough. Above that there is very little difference to be had and 100-1000 makes no sense except for marketing If you would like to hear the change in frequency response caused by a damping of 1 amplifier, get a 10 ohm 10 watt resistor or a resistor similar to your speakers nominal impedance. This is not critical, if you play low volume get 5 watts. You will learn two things. Besides hearing the change of tambur of your speaker you may note undefined bass, rolled off treble, loss of air, loss of definition. Dont get into imaging too much. Play lots of different material, just listen to the frequency balance. If the vocals jump out at you. If the symbols loose their sheen. Check the temperature of the resistor, start out low volume and don't burn yourself. At high levels you may be surprised how cool the resistor is. That resistor is getting half the power and the speaker half. You may find the resistor gets barely warm and thus shows you how much, or little, power you are using. The resistor goes in either lead in series with your speaker. You might experiment with other values.
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@utrak
I’ve got a question for the tube amp designers. How much of a difference does the power transformer make in a tube amp design? Is the output transformer more critical or the power transformer or both? I’ve read that the output transformer is absolutely critical and I know that they can be very expensive. However, how much would it degrade a good design to just go buy an Edcor power transformer, which I’ve heard are decent transformers, and use it with a high-quality output transformer?
Id better take this one since my amplifiers happen to have output transformers. I will admit in 1982 I did not know much about output transformers, I like many shied away from a traditional tube amp and decided to take Julius Futterman's work one step further and make it have DC output. The large output cap in Futterman's design is electrolytic and right in series with your speaker. Sold that design to Counterpoint and it became the SA-4, won some awards; yada yada yada. I wanted to make a push pull EL-34 tube swappable amplifier so I decided to get into transformer design. You couldn't buy any off-the-shelf quality outputs in the 80s. It took a lot of time and thinking and trying things. Crowhurst taught me. Now to your question, both are important in different ways. There was an old adage that in a mono amp the output and power should be the same size.. not terribly sensible but easy to say yay or nay to an amp at the swap meet. The power and output do entirely different things. They both share the desire to be low loss. Loss in the power transformer makes heat, loss in the output robs potential power. Large power transformers have about 5-10% loss which becomes heat. They have a primary made of 100 feet of 16 ga wire in my case. Resistance is 1-2 ohms which is why I have trouble believing a 12 ga power cord can much enhance the situation. Power transformers work at 50 or 60 HZ. I make those differently for each frequency otherwise the flux is 20% higher in Europe. Output transformers are an entirely different animal. They have to work over a wide band of frequencies. To make a stable amplifier the output transformer has to go out to about 65 Khz. The laying down of the wire in an output transformer is most important. We also interleave the layers which means for instance, wind part of the primary, then part secondary, then part primary, then part secondary, then part primary. That is called a 5 layer or 5 interleaved transformer. While some makers claim 11 interleaves this causes too much capacitance and a measurable rise in plate current above a few KHz. If you play loud trumpet music you can bur up the tubes, especially if the speaker impedance is low there. It's all tradeoffs. What happens next is how the transformers behave in the amplifier. The amplifier is literally build around the transformers. There is a big difference between designing a transformer and specifying one which is what most designers do. Designing means figuring out all the wire gauges, insulation layers, interleaving, core size, stack, bobbin. Goes on and on. Specifying a transformer means saying - 3db at 15 hz and 65 Khz. Done! Hope the transformer house has an old guy who knows how to do it. I have never been satisfied with outside vendors even when they wind my design. They have horrible problems with uniformity. Power transformers are easy, just count the turns and get the wire on there any way you can. I've not tried an Edcor power, I have the outputs. Most of them are made for tube rectifiers I believe. I'm not fond of tube rectifiers in amps above 30 watt, ,certainly not 100 watts. Were you planning a tube rectifier? Which one? What output transformer might you buy?
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@almarg
Roger, I have a sincere question. What specific technical considerations lead you to be so negative about Ralph’s paradigm paper I hesitate to answer your question for the fire that will reign down on me. But this is the last I will deal with Because the paper does not make electrical sense and appears to be a excuse for making a certain kind of amplifier that has limited applications. Which is just fine. It is cleverly written, I will give you that. Perhaps Ralph could provide some frequency sweeps that show the power is constant? Then show how the speaker response is thus modified? Words alone do not convince me. AL, you appear to know a good bit of electronics, do you not see how this paper parts from accepted electrical theory? This first sentence causes me pause.. " The Power Paradigm assumes that amplifiers produce power and speakers are power-driven " Speakers are not power driven, they are voltage driven. Lets look at the low end resonance. Most speaker climb to 40-60 ohms at resonance (35 hz lets say). The speaker designer does not want the voltage to rise into that peak. He already accounted for that peak with the mechanical damping of his speaker. We do not want to feed more power into that frequency, the speaker is telling us not to by raising the impedance. The sensitivity of the speaker is rising rapidly at resonance. That is what resonance is and it occurs when the mass of the cone no longer determines the motion and the stiffness takes over. That is what is going on. About high order harmonics I will ask you. Would you rather have an amplifier with 3% 3rd and 0.01 7th-11th or one with less than 1% 3rd and 0.02 7th -11th? My point is that the high ordered harmonics are rather small. Intermodulation will follow a similar path. I will say this. I have two M 60s on my A/B system and I like Ralphs amplifier build, layout, cool circuit. I dont like the high output impedance or high distorton. I do like Ralph’s amplifiers better than his paper. I wish he would just drop the paper. Its embarassing. Can’t he just say what his amps do without having to invent this story? Loudspeakers that operate under Power Paradigm rules are speakers that expect constant power, regardless of their impedance. Examples include nearly all horns (currently the Avantgarde Trio is the only known exception), ESLs, magnetic planers, a good number of bass reflex and acoustic suspension designs. Horns, ESLs and magnetic planers do not get their impedance curve from system resonance and so benefit from a constant power characteristic and indeed, many of these speaker technologies are well-known as good matches with Power Paradigm amplifier designs. This paragraph is particularly disturbing. Is he saying ESL speakers are constant impedance? The Quad 57 goes from 50 ohms to 1 ohm. Peter Walker specified and designed the QUAD II with a damping factor of 20. He designed the speaker and knew what was needed. The 57 also happens to have a DC resistance of 0.5 ohms. Therefore as little as 50mV of offset will put 100 ma through the transformer, upset the bias of the amplifier by 25 %. It is hard to keep a non servo DC amp consistantly below 50 mv even durring one listening session. You have to disconnect the speaker to see the offset easily on the meter. This is not fun. |
@corby2 Hello, I have a budget system I like. It has a 25 watt Will Vincent Balwin tube amp with Coincident Dynamites. I do not have an audiophile power cord. How much do audiophile power cords help with the amp? I was thinking of getting to Anticable stage 3 power cord. Thanks, Cory in Reno Hi Corby, Very few amplifier makers wind their own transformers, but I do. When I wind a transformer for a 25 watt amplifier it is about 150 feet of 24 ga wire. After I am done I really dont see how 12 feet of 18 or 16 or 14 ga wire will make any difference. If you measure the resistance of the primary circuit of your amplifier it is like likely near 5 ohms given that it is 25 watts. This is easily done by unplugging the amp, turning it on, putting an ohmmeter across the two prongs of the power plug. Now you will know the total resistance of the primary loop. The total resistance of the secondary loop (reflected to the primary) is similar to that so double what you just measured. Now ask yourself how much a power cord of 0.01 or 0.1 ohm or 0.5 ohm is going to make when added to that number. The claims about RF shielding are absolute bullshit. Along with any other specious claims. Just get a cord with good connectors. |
@tomic601
RM - took a hiatus from the book, restarted on page 59....junction temps....had a bad experience with ON Semiconductor thermal tracs.....I know you are a tube guy, can you comment about the diamond topology ?
Not sure what you mean by thermal tracs? ON semi is making the Motorola parts. I dont know if there is anything new. Do you have a part #. |
@analogluvr
Over voltage can cause mechanical hum in a transformer
Thanks for pointing that out. The flux (and thus mechanical buzz) of a transformer rises sharply at some voltage. That point is up to the designer. I try to get mine still quiet at 130 Volts but we are getting up to 125 now in our houses so might have to go higher and wind for 125 rather than 120. Small amounts of DC on the line make things worse expecially with torroids as they have no gap. 0,5 volts of DC is enough. We make a power cord with a device to block the DC. Ask Clio, or you can make your own. Im not trying to sell anything here or be accused by one who does. Power transformers are a pain in the ass. If you make them bigger to reduce the flux they make more noise due to larger size. Ive been around the block several times on this. All our tranformers are silent at 2 feet in a very quiet room. My thought is if you cant hear it at the listening position whats the problem? Who sits next to their power amp? If you want someting lower noise I can make it for you. Power transformers can become noisy with age. Spongy feet or a bed of sand helps a lot to decouple from the rack or floor. |
@iamisaf
When units are powered on I hear a very mild hum noise from the amplifier unit, if connect amplifier directly to the wall outlet I don't hear any hum noise. If I do the similar setup other side in the basement I don't hear any hum when connected to wall outlet or thru panamax power conditioner.What might be the issue?
The two sides of the basement may be on opposite phases of your 120/240 line. Houses are wired to try to balance the load on each phase. One phase may have DC or slightly higher voltage. Why are you using a power conditioner anyway. I dont. Sorry to say this is a horrible product. Anytime they bring all you phone, cable, power, God whatever into one box its a horrible idea. If you can send it back please do. Modern devices generally do not need surge protectors and they tend to catch on fire!! https://www.crutchfield.com/p_299M5300PM/Panamax-M5300-PM.html?awkw=75647650225&awat=pla&awn... |
@skiramp
Hi there would appreciate some help, I am shipping my Macintosh intergrated amp 200watt plus my def tech bp7000 sc to Thailand to live with me ? Very dodgy mains power !!! I am toying with the idea of ups or stabilizer or whatever , for some protection ? Against voltage drop . The def techs have 1800 watt driven subwoofers x2 of course ? I know that the equipment will never be driven at capacity, as house would fall in , your thoughts on a possible soloution,,, thank you : skiramp
I dont know the specifics of your equipment as to low voltage. Solid state amps I have designed work fine down to half line voltage. Some do not. Well designed switching supplies are low voltage protected but if not they smoke and burn up. Get a power regenerator with wide voltage tollerance and let it deal with it. I do mean regenerator like PS audio makes. IF it fails you can send it back. I would also question what you are doing with those big subs. Are you watching Das Bot. I wish you well in Thailand. Its a lovely and exotic place I visited many years ago. |
@testpilot How do you block DC. Connect two diodes back to back in parallel and insert in hot lead of power cord. |
@stargazer3
For the OP what are the pros and cons in relation to damping for amplifiers; eg Hegel store great reliance for damping in relation to driving difficult speakers.
There is no con to high damping if done properly. However more than 20 will have little effect and may cause the designer to do some bad things to achieve it. When a designer goes to maximize his favorite parameter he can go too far and other things will suffer. In this case stability from oscillation. There are many amplifiers out there waiting for the wrong load and their own destruction. I have seen many amps with very high damping oscillate into a 0.1 uF load which is typical of some speaker cables. Smoke and shorted output transistors was the result. The cause is too much feedback and assuming that if the amp is ok with the standard 2 uF test load it will be stable with smaller capacitive loads. Many well known amps are not. I tested an early ADCOM that took of with 0.1 uF. I did it for one second. A few more seconds would have been the smoke test. Do you have a link to Hegel, I would like to read it? |
@ atmasphere
In one post Roger says it doesn’t make much difference, OTOH in the very same post describes the power cords that he made up special and how anyone can do it. I have to assume that he felt it was worth doing . Ralph, what is OTOH mean? Im a newbee.The cords with diodes make a difference when needed. I think I have been clear and consistant here. Your amp draws heaps of current when played hard. Something heavy ga might help a little at full power. At idle Im not so sure. I note the current draw of the M-60 goes up quite a lot at full power testing. How long can I run an M-60 sinewave at 60 watts into 8 ohms before the tubes get unhappy? |
@prof
I could really use some help betting a better grasp of amplifier/speaker interaction. Specifically, in what sense a speaker is "easy to drive" for an amplifier.
This seems to generally relate to two parameters:
1. Speaker sensitivity
2. Speaker impedance (and phase angles etc).
I’ve seen speakers with higher sensitivity but lower or wilder impedance termed "easy to drive" and speakers with lowish sensitivity but higher and smoother impedance being "easy to drive." So I’m trying to get a grasp on what it means...in practical and possibly sonic terms...when a speaker is "easy to drive"for an amplifier and what you get when trading off sensitivity vs smooth impedance.
To turn it in to a practical example:
I owned the Thiel 3.7 speakers. Here are the Stereophile measurements:
https://www.stereophile.com/content/thiel-cs37-loudspeaker-measurements
Note the 90.7dB sensitivity, but with it seems a fairly challenging impedance.
***********GREAT QUESTION, EVERYONE READ THIS************** Ill take this one speaker at a time. The 3.7 is THE speaker that birthed the RM9-SE and RM-200 designs. Those are AB2 designs that use positive grid voltage to extend the output current range of an AB1 amplifier. We had a MK1 RM-9 customer who was going through output tubes at an alarming rate. The speaker and his love of Miles was driving the tubes hard. First, JA did not point out, as he now does that 2.83 volts is NOT the proper voltage for a 4 ohm speaker. Its 3 dB too high so the 4 ohm sensitivity of the 3.7 is 87 db. Its even worse because this it a 2.5 ohm speaker so take off another 2 and make it 85 dB. So its really not a very efficient speaker. I made the RM-200 with taps down to 1 ohm for speakers like this to preserve the damping, reduce the tube stress and lower distortion. The 2 ohm tap on the RM-200 is ideal for this speaker. Mismatching the load on a tube amp makes it work really hard. This is a 2.5 ohm speaker so good luck. Many SS amps will not play this speaker well. Thats your the gist of question #1. #2. Phase angle.. As the phase approaches 90 degrees the output devices have both full voltage and full current across them. The dissipation in SS or tube amps goes wildly high. SS amps are sure to current limit, tube amps just take it. This is why tube amps have a reputation for driving such loads at the 3.7 and ESLs. Thats all for now. This great question deserves several parts. Anyone please feel free to ask as we go for clairfication. |
@prof1
I also wonder how the introduction of a subwoofer alters the load to an amplifier. So say if you have a powered sub and you crossover to the sub from the mains at maybe 80 or 60 Hz. Once one has off-loaded much of the low frequencies to the sub, I wonder how much the main amp "sees" and if that, in effect, is like adding a more powerful amp in to the equation .
I assume you are using some crossover to rolloff the main speakers. Is that via and electronic crossover or the series caps found on some subs? Makes a difference as to voltage the main amp still has to produce and thus clipping and IM distortion. The correct way is to rolloff the main amp at its input so it never sees the bass voltage. |
