In your opinion , do push pull amps work better with 8 ohms or 4 ohms. .I am under the impression the lower the ohms, the more power is demanded from the amp....Another question, are there low powered SET amps ,and high power SET amps? I'm looking at a 40 watt 845 tube amp for my 8 ohm, 89 db speaker.. just cked the Thor has a 86 db W18 midwoofers(2 per cabinet) and a 88 db tweeter. Will an 845 amp rated 40 watts be able to drive the 86/88 db speaker? With authority, bass, mids, highs, in dynamic sound stage? Synergy? Or poor match?
Having said that, my Primaluna PL2 with KT88's, 40wpc, has no trouble driving the Proac D15's, 88db, to louder than WAF levels in our 15 x 30 x 10 room.
>>05-21-07: Atmasphere Anytime you are investing in tube amplifier technology, that investment will be best served by a speaker that is at least 8 ohms or more.
Tube amps, with rare exception, have reduced performance into four ohms. <<
So, it seems that in general, Tvad is correct. Even though the Atma-sphere MA 2.2 may well drive the Woodmeres 4 ohm impedance to acceptable levels, the inference is that it would drive the Defintion AFI with 30 ohms impedance a helluva lot better. Furthermore, the 60 day in-home trial of the Defintions are a huge plus. Almost essential. So now will anybody give me their impressions of the "sound" of the Zu Definition, since there seem to be divided camps on this issue? Thanks.
Hi Gregm, you might ask Nelson Pass or Charlie Hanson of Ayre, both of whom make zero feedback designs.
FWIW, negative feedback is a *destabilizing* feature in amplifier design, not a stabilizing one. This is a common misconception about feedback.
Direct-coupled transistor amplifiers tend to use feedback as part of their means to control DC Offset at the output- IMO an inappropriate use of feedback, as it requires a greater amount of it to do the job. It may be the traditional way to do it, but in the world of high end audio, 'traditional' is a weak excuse for a solution to a problem.
Normally the tube is a self harmonic generator ( that does not exist on the original signal/recorded signal )
Raul, I would have thought you would have educated yourself better before making such an obviously false statement! You are in a lot more trouble with transistors in this area then you ever would be with tubes! Look how many tube amps can actually operate with low distortion with zero feedback, and then count how many transistor amps that do the same thing. The zero feedback transistor amps are *sorely* outnumbered!
If we run feedback on our amps, which are OTL, we can get the THD down to 0.001% at full power, but who'd want to (just like frying an egg on the sidewalk)? It is true that you reduce a lot of distortion that the ear does not care about, but you increase the distortion that the ear *DOES* care about!
Ultimately it is the rules of human hearing that are the most important factors in audio...
+++ Please could you explain how the tube technology can be " accurate " to the recording +++
Sure Raul. Perception of music and the accuracy thereof is 100% subjective. To my ear no amplification device on the planet can come as close to a real piano recital as a SET amplifier.
+++ Normally the tube is a self harmonic generator +++
That is not true. Always the tube and the transistor are self harmonic generators. Transistor generally being much worse, up 70% THD. Amplifiers by design compensate to correct these flaws. My ear prefer vacuum tube solution for now.
Yes, tube amplifier require much more careful speaker matching as they have much higher output impedance than a transistor amplifier. People who do not understand this better stick with transistor amplification.
Dear Paul: +++++ " prefer tubes, as to my ear, they achieve the most accurate.....of the recorded material. " +++++
Please could you explain how the tube technology can be " accurate " to the recording?
Normally the tube is a self harmonic generator ( that does not exist on the original signal/recorded signal ) and normally too due to its high output impedance a tube amplifier is everything you want/like but accurate handling the electrical speaker impedance curve.
David, tubes do sound magic, but not to be a party pooper, you are probably enjoying some of the harmonic colorations. Many folks do find this pleasant to the ear and since you paid for it, there is no reason for you not to enjoy it.
Better suited speakers will give you a much more accurate and natural sound, with less of the colorations. You may at first not enjoy it quite as much, and it may actually sound more like a transistor amp.
A good tube amp setup sound remarkably the same as a good transistor setup. I personally prefer tubes, as to my ear, they achieve the most accurate and natural reproduction of the recorded material. That you will only experience once you get components that work well together.
I think many will agree with me that the process of acquiring the correct components can take many years but is very enjoyable every step of the way.
Don't know if anyone is still looking at this thread (which I found very informative as a newbie), but I thought I'd just report back now that my Yaqin MC-100B (4 x KT88's) has been with me for a couple of days.
It sounds amazing!! Okay, it's my first tube amp so maybe this is just me discovering that I prefer tubes to transistors, but I'm hugely impressed. A very full-bodied, yet smooth sound with lots of powerful bass...lovely. By the way, I didn't get to try the supplied chinese KT88's as one got smashed in transit. It's running with a matched quad of winged-C KT88's.
Anyway, to get back back on topic, it drives my B&W 804S speakers, which I believe are considered a difficult load, very well indeed. In 'ultralinear' mode (apparently 60wpc) there is plenty of volume (without clipping) available and the bass is very deep & powerful. There's a lot more of it than there was with my transitor amp, too...which is to my liking. No sign of the sound becoming confused and incoherent at higher listening levels. In 'triode' mode (30wpc), the amp still drives the speakers okay at lower volume levels, but I sense that it does struggle a little when asked to play louder . I prefer the character of the sound in ultralinear mode anyway, so that's of no concern to me.
But, even though I'm more than happy at present I guess I should still look to audition some alternative speakers, as maybe I just don't know what I'm missing!
The point of the topic was to ask the GENERALIZED question that tube amps prefer 8 ohm speakers(though even 8 ohm speakers can dip to 4 ohms on huge orchestral challenges).
The answer to that is 'yes!', regardless of the tube amplifier technology.
The 4 ohm taps on almost all output transformers (excepting those that the 4 ohm tap is the *highest* tap). perform to a lower level than the other taps. The loss in bandwidth and increase in distortion is readily measurable and audible.
IOW: "Anytime you are investing in tube amplifier technology, that investment will be best served by a speaker that is 8 ohms or more, all other things being equal."
Eagleman, feel free to ask w/o feeling you will get criticized. I get snides and insults due to lack of tech knowledge, snotty attitude, "mister-know-it-all", negativity, closed minded-ness. So as long as you don't follow me, you'll do all right here. btw I liked your question and Newbee's appropriate answer. I was not aware of how the 4 ohm and 8 ohm taps respond on different fq's. I still don't grasp ohm idea. Only that 4 ohm draws more volts/current from the tube amp. So it was a good question.
If bass control seems to be a problem for you when you use the 8 ohm taps use the 4 ohm taps. If you use the 4ohm taps and the highs are not smooth use the 8 ohm taps.
Simply said, use the taps which sound best to you. My guess is that if you are listening at moderate levels the 8 ohm taps might sound best.
Ok, here is a question that may show my ignorance of this subject but, I will ask anyway. I have a TAD-60 AMP (60 WPC ultralinear).. It has 8 and 4 ohm terminals. I am running Vandersteen 2CE signatures which are rated at 7 ohms nominal and 4 ohms minimum. I am currently using the 8 ohm terminals in my set up. Would I be better off using the 4 ohm terminals? If so, then why. If not then why not. Thanks, Eagleman
That is sad. The failure you mention your experienced with your tube equipment would not occur had you been using solid state.
I own (and have owned) solid-state amplifiers that are extremely musical and will work on most speakers.
++ I look for certain tube amps that can carry a relatively heavy load +++
These tube amps are not the best sounding tube amps and more often than not, cannot compete musically with good transistor amplifiers.
+++ though even 8 ohm speakers can dip to 4 ohms on huge orchestral challenges+++
Musical genre does not influence speaker impedance. If speakers dip to 4 ohm on Orchestra, they will dip to 4 ohm on every genre of music known to man.
Speakers rated at 8 ohm that dip as low as 4ohm are not suited to for tube amplification if quality reproduction is a requirement.
+++ TRhe point of the topic was to ask the GENERALIZED question that tube amps prefer 8 ohm speakers +++
No it wasnt. You asked a myriad of questions but not what you state here.
+++ Which is fine. I'm staying with 8 ohms, and thats that.+++
I dont believe anybody told you not to purchase an 8ohm speaker. Most posters indicated that there are other factors you need to consider also.
Fact is, most of the posters here have system that can do orchestra. By your own admission, your system cannot and you do have 8ohm speakers already.
Raul, I am not going to argue with you, mainly because I do not quite understand your comment. I think this is mostly due to the fact that neither you nor I have English as our mother tongue.
Transistor amplifier have lower output impedances and are therefore much more suitable for the majority (99%) of modern speakers. They can easily maintain a constant voltage against a speaker load where a tube amp will struggle. In the perfect world, vacuum tube amplifier should have speakers rated at 64ohm/128ohm and higher to do so. Hopefully one day I can get somebody to build me speakers like that to fully optimize my tube amplifiers.
I also believe almost all vacuum tube amplifiers are used against speakers where they do not perform well Bartokfan is a good example of this.
However, you are incorrect if you say vacuum tube amplifiers cannot maintain a constant voltage against a loudspeaker. It is simply a more difficult to achieve.
You are welcome to disagree and I know and respect your view on transistor vs. vacuum tube.
Paul , ss amps may be the "ideal" for demanding speakers, but since I do not care for ss amps, I look for certain tube amps that can carry a relatively heavy load. I agree stats/panels/ribbons need ss current for optimum response. Vandersteens need good ss power as well, at least hios larger models. TRhe point of the topic was to ask the GENERALIZED question that tube amps prefer 8 ohm speakers(though even 8 ohm speakers can dip to 4 ohms on huge orchestral challenges). I think the consensus agreed, though some here want to split hairs and bring up their special agenda and objections. Which is fine. I'm staying with 8 ohms, and thats that.
Yeah but can they produce a musical image equal or similar as does 2 tube amp labs that i have in mind. Its all about who can get closest to the high fidelity musical image. Audiofeil feels since i know nothing of the tech side and so suffer from deafness. 30 yrs audio critque and now I am deaf.
Dear paul: The statement is totally accurate, it is not talking about " speaker has a benign impedance curve across the frequency range. " like you state.
+++ We are more interested in which labs are actually producing a tube amp to meet demanding power hungry speakers. +++
The best amp for meeting the demand of power hungry speaker is called a transistor amp. A person attempting to use a tube amp on said speakers is called ignorant (I am being kind)
+++ I am only interested in the end result. +++
No, I suspect you are interested in your own opinion ...
Tvad, I should have posted about driver in house design vs mass market poly cones, on the topic Harbeth vs Tyler. i goofed up, and mixed comments. Back to topic of tube amps transformers and the resistance from the motor and crossovers in speaker designs. A low volt tube amp, or lets say one that has trouble maintaining proper volt current when demand gets high, will not bring out the FULL potential of certain demanding speakers. Go to Jadis' web page, look inside the DA88. Designed to meet any demand from any speaker. Quality doesn't come cheap. Although certain chinese labs are comming along quite nicely. We can talk theoy here all we want. We are more interested in which labs are actually producing a tube amp to meet demanding power hungry speakers. I'll leave the tech stuff to their engineers. I am only interested in the end result. Does the setup produce a high fidelity musical image? Thats all, nothing more.
+++ the only way to achieve constant voltage drive with a changing load impedance is by having very low amplifier impedance+++
This statement is not totally accurate.
Constant voltage can be achieved when the amplifier has a relatively low output impedance compared to the speaker impedance AND when the speaker has a benign impedance curve across the frequency range.
In the same manner that some carts require very careful matching with a specific tonearm to perform their best, vacuum tube amplifiers require the same careful attention in matching them to the appropriate speakers.
But then I am not telling you something you do not know already Raul? ;-)
Raul you hit on a essential issue in tube amp output. The impedance factor of the speakers, how difficult is it to keep the motor of the speakers moving in a musical line as the fq's change or amount of fq's are thrown at the amp. Which big orch does. Here the quality of transformers and other internal parts is critical. Thats why i leave it up to the amp manufactore to provide me with the best possible dynamics to run the demanding speaker as are the Seas Excel. I think I have the correct amp. I am waiting on components to arrive. many folks here boo hoo the Seas Excel with no foundation of their criticisms. They seem to be disgusted with my cheering the Seas labs creation, The Excel. Funny that these complainers have nothing to say good about their favorite driver. (not speaker, DRIVERs). Most don;'t have a clue what driver is in their speakers. Most drivers are bought on the open market. Seas actually makes their drivers IN THEIR OWN LAB> Which speaker manufacturer does that???
Dear bartokfan: +++++ " This is the way loudspeakers behave. Loudspeakers are not constant power devices. Loudspeakers must have a constant drive voltage to provide a constant acoustic output with changing frequency. As demonstrated by the simple mathematical relationships shown above, the only way to achieve constant voltage drive with a changing load impedance is by having very low amplifier impedance. " +++++
This is what you can read on the link you posted, as you can " see " this subject is critical.
Now, the tube amplifier technology has many trouble to handle in the right way all those speaker needs, so ( if you want to go with this technology ) you have to make big trade-offs with it. Of course that you could choose for SS technology that could mate in a better way your speakers needs and your music sound reproduction priorities.
raul. i googled amplifier output impedance and got several hits. The info if over my understanding, but will try to work with the ideas. I grasp that quality of transformers is vital in tube design, especially when driving a devil of a speaker such as are the Seas Excel. The motor on these speakers causes havoc on most tube amps. I assume. Lets see if this link loads: http://www.transcendentsound.com/amplifier_output_impedance.htm
Dear Bartokfan: The speaker efficiency ( 86db,89db,etc )is not the only subject when you want to choose an amplifier, either the nominal speaker impedance ( 8 Ohms, 4 Ohms, etc, etc ) because what you need to know is not only the nominqal impedance but the electrical curve speaker impedance where you can " see " how low goes that impedance.
The other critical subject that you have to take in count is the output amplifier impedance that IMHO must be a low one: say below 0.1 Ohm.
David, the best advice I can give you is to talk to a few speaker builders/manufacturers. They will be able to give you very good advice. There a couple on the BB like Audiokinesis who I am sure will be happy to talk to you. A few others are omega, decware, coincident etc.
I have speakers rated at 88db/1watt/1mtr sensitivity that I drive to very loud levels with a 12wpc tube amp. The bass really pounds and I can measure it down to the mid 20s (albeit at 10db). I can do that only because my speakers are very tube friendly. Some other poster mentioned his 200wpc amp is barely capable with 96db rated speakers somewhat ridiculous no? If I hook up my 22wpc SET I can blast the doors down.
Hi Paul. Thanks for your comments. I really do want to switch to tubes and will move away from B&W's. Probably shortly after receiving my first all tube amp!
Sticking with floorstanders that have a healthy bass output and are not bright or overly forward sounding, can you suggest any manufacturers/models I should potentially be shortlisting?
Cheers David (have to invert my name and use divad as david is always taken as a username!!)
Hi Divad. I tried to post before, but I cannot see the post so here goes again.
First off, I am a very pro tube guy, but I would advise you very strongly against going tubes with your speakers. Your speakers are not suited for a tube amplifier.
You may get them to work by using a big tube amp, but it is never going to be a good match and neither your speakers nor the tube amp will be sounding their best. Youll be much better off with a solid state amp.
If you really want to try tubes, you need to ditch the B&Ws.
Grant, my KT77 comments are based solely on listening to the JJ variant. I'm not sure how the Osram (didn't know they made KT77) and Mullards would sound.
In my Jadis DA60 and Dennis' (Badboss429) Quicksilver, a bunch of us (including Mechans) compared the JJ E34L blue glass, JJ KT77, vintage 1960s Mullard EL34 XF1 (EL34 Holy Grail), and JJ KT88 blue glass. The KT88 came in last. The rest of the tubes had a variety of opinions. Overall, things seemed to split between the Mullard and JJ E34L, but many of us couldn't get past the powerful, intoxicating lows of the JJ KT77.
From what I heard, the first batch of KT77 had issues with the tube pins. The octet I bought in January/February 20076 had this issue corrected. Didn't have any fail, either, but it's a complaint many have put forth with JJ power tubes in general. I have an octet of E34L Blue Glass, and one day while measuring them about three weeks ago, I found one was as dead as a doornail. That came as kind of a shock.
Tvad - FWIW, dealing with like kinds, ie SED's, I found the 6l6GC slightly mellow thru the upper mids/highs compared to the EL34 in both of my Primaluna amps which were primarily designed around the EL34 or the KT88 and to my ears both sound best with that the tube around which it was designed. I've been sort of interested in hearing an amp designed around 6L6's but I haven't found one yet. I tried them in my Baron but they were to hot - I'd have to get it modded (it takes 5881's).
JJ is the only maker of KT77's right now that I'm aware of. On AA several posters have been high on the sound they make, but there is some strong comments on quality control and pin size. FWIW - you probably already knew that.
I think the point Newbee made about the EL34 versus KT88/6550/KT90 is something that REALLY needs to be lauded. EXCELLENT POINT!!!
The EL34 is a tube that is going to be in many of these amplifiers. And, while it is my favorite of the traditional push-pull amplifier tubes, it does has its shortcomings. As Newbee pointed out, you are going to give up those low frequencies (and overall power) in exchange for those wonderful mids. Please be aware of this.
Another tube to consider is the KT77 made by JJ. VERY powerful bass, and good power overall. You still don't match those EL34 mids. Consider it a great tube slotting between the EL34 and the KT88. In more than a few amps, we actually heard MORE emphatic bass with the KT77 than the bigger tubes, combined with some seriously better midrange.
Great vintage monoblocks if you can find them. The put out 100 w/ch and weigh about 45 lbs each. The irons are monstrous, but they sound increadible with low efficiency/low impediance speakers.
Thanks for the advice. The Yaqin MC100B that I was looking at has 4 x KT88's and adjustable bias for each tube - access via marked holes in the top plate. I'm not frightened to get into the techie stuff so that appeals to me. A screwdriver and multimeter job, I guess?
Think I'll take a gamble on this one. Can probbaly get hold of one for approx £400 and if I get on with it then I can look to upgrade to something more classy.
If you want powerful bass stay with an amp that is designed around the 6550/KT88/KT90. EL34's are potentially great mid-range tubes but lack the bass of one of these power tubes. In my systems the KT88 has more 'color' (as does the EL34) than the 6550 or the KT90. It reminds me, somewhat of an EL34 with balls.
In your place I would start with an amp designed around the KT88. There are a lot of different brands with different tone available for substituting in KT88's, most new production are quite good.
Re Chinese tube amps (I've got three) be mindful of a couple of things which can be important. Support is #1! If you're not a techie type and can't maintain and fix things yourself, get something which can be serviced without a return to China.
Also, one of the things that some Chinese amps are starting to appear with are on-deck bias meters and bias pots for each tube. Highly recommended feature! Allows you to easily maintain proper bias, follow tube wear, and replace or substitue tubes. Auto bias curcuits are also good for new tube amp users, but IMHO, in the long run manual bias with post for each tube are far more beneficial to the user.
Also, some Chinese amps are now coming with fuses that protect the bias curcuit in case of a tube short. Very important unless you can solder in new resistors. The sonic compromise by having a fuse is, IMHO, minimal if any for most folks.
Thanks for the responses - seems like a real friendly forum.
To some extent, it looks like almost any tube amp will represent a bit of a gamble as long as I retain the B&W 804S's. That's why I was looking at the more affordable chinese brands first, before I consider investing more.
I've not long had the speakers (love the midrange when paired with my Sugden, but the combo tends towards brightness), but would definitely consider trading them for some similar sized speakers that present an easier load and would widen my choice of amps. I always wanted to audition some Spendors but never got around to it - maybe I should now.
I think I'll probably go for a tube amp first though and just see how it works. Another amp I was considering is the Ming Da MC34-AB. Rated a little higher in terms of wpc, but using EL34's I believe. It seems to be more well known, so there there may be someone here who's tried one with B&W 8 series.
Above all, I don't think I want to stick with a transistor amp as, from what I've experienced so far, tubes seem to reproduce music the way I like. A smoother top end, an open midband and a full-bodied bottom end. I do like a powerful bass, so that may present problems given that my speakers appear to demand a lot of watts to produce that. To be honest, I also like the idea of tubes because I can then experiment with different tubes in order to 'fine tune' the sound - something I've enjoyed doing with my guitar and headphone amps.
Tvad, This info came from the horse's mouth. I've never seen it in print, its what Ty told me.
Re impedences, there was an excellent thread in which Duke participated, within the last 6 months, where in not only were speaker impedence loads discussed but amp output impedences were also discussed. Amp putput impedences are seldome discussed and their impact is not generally understood. Most folks assume they are constant but they are not, they rise and fall with frequencies and have considerable impact of the sound which is produced by a speaker. You might be able to ferret it out by looking up some of the threads in which he participated. And, I think you are right the Ralph could help explain, but I can't recall if he participated in that particular thread. Maybe you could start a thread and get a discussion of this going and invite Duke and Raplph to participate. This may help you. Good luck......
Divad, I am running a Tube Audio Design-60 with Vandersteen 2CE sigs (86DB I think. This amp runs 60 watts ultra and can be switched on the fly to triode (30 watts). This amp has plenty of juice for the vandys. I listen mostly to classic rock at room filling but, not loud levels and the vandys really sing. See Larryx7s post above. The TAD-60 can handle many EL-34 type tubes and is easy to bias. Check out the reviews on this amp. I haven't heard many other tube amps to compare but, I bet that it competes very well with amps in its $1300 class...
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