Passive Pre - No Regrets?
Here's another one for you. Intact Audio A transformer winder from hell. With discussion on how to tune the transformers to your system. Not for the faint of heart but results can be stupendous if you are willing to invest the time and effort to optimize it. |
I have had a Placette for over a year now. I will never go active again. I have hi output low impedence sources and sensative hi input impedence amps. This is perfect for a passive linestage. Not everyone has components as well suited for sure. If I connected my source to my amp directly the volume was way too loud. This means my amplified linestage was really an attenuator! Going passive was a real shocking improvement for me. I will also say it is hard to find a phono stage suited for this. Low impedence out is hard to find especially with tubes.I have no opinion on my resistor ladder style unit vs a transformer based unit other than less passive friendly components than mine could benefit from transformered units and their potential 6db gain. They are more likely to color sound than a resistor ladder which could or may not be beneficial. Your results may vary in other words. Good luck! I like the Placettes remote control as well and the fact that a passive doesn't need a power cord(upgrade)since only the control functions use AC power not the signal path. ET |
Good point about phono preamps, Electoid. My solid state Gram Slee Era Gold mkV phono preamp(+ELP "transformerless" stepup) has an output of 240mV - 1.08V max. That's works for my Art Audio PX-25's 0.7V input, but not really enough for my Welborne DRD 300B monoblock's 1.5V needs. I have to use the +6dB setting on my TVC sometimes, which has it's own drawbacks. |
"I don't have a thimble's worth of his experience or knowledge, and he always seems to make very measured and reasoned statements. So, I'm sure there are very good reasons for what he says." Yes I agree he is a talented guy, but so are the fellows that design the passive units. His reasons are stated above..He designs and builds active preamps. Personally have no preference to amplifier design. As long as it suits my taste.. any design will do. Thanks for the link Herman..never seen this site before. Good listening |
This is at least the fourth thread I have seen on the active vs. passive line stage question, and they all result in the same response. Some cannot conceive of anything other than passive and others prefer active, with many having tried both. What does this tell you? System and tastes vary, I would think. It very much suggests that little is exchanged other than personal experiences. Would it not be great were we able to post sounds rather than words? |
Remember that those interested in autoformers have to be sure that there is absolutely no DC on the output of their sources. Any DC getting through can be bad for amps. By contrast, one of the primary benefits of transformers is galvanic isolation, or making sure no DC reaches the next stage. Of course, if a person is sure that all their sources have no DC, then there can be sonic benefits to an autoformer over a transformer for volume attenuation. |
"I had to laugh at Mr.Sphere's comments about passives not being able to drive the cables... that's a pretty broad statement. With the right source some of these passives(TVCs) will spank an active all day long driving cables. Being he designs and builds active preamps..I'm not surprised at the negativity towards passives. Man.. this jet black background coloration is working for me.;-)" It might surprise you that we've built passives too. Of course, we do think that our line stages exhibit a new possibility of line stage capability (and we are who we are- no surprises there- if you think I ought not offer comments I'm open to suggestions). I like to take advantage of the capabilities of monoblock amplifiers by putting them very close to the speakers, thus keeping the errors introduced by any/all speaker cables to a minimum. This means that the interconnect has to have some length. There are no passives that we have found that are able to drive the distance without an audible artifact. Our line sections can drive 30-100 feet with no difficulties. Simply out of the question with passives unless the control is at the input of the amp. |
I'm still waiting for my Placette, which should be here this week. Just for the record, my IC from the Placette to the amps will by 1M Cardas GR or 2M. Guy, Mr. Placette, thought I would have no problems with the cables and my equipment. He also suggested that placing the Merlin BAM between the Placette and the Amp might be a good approach. So, if the Placette can't beat the CAT, I think I can assume it would not be do to capacitance issues in the ICs. I see Atmasphere's point about running 30-100 ft cables, which would suggest the need for an active and perhaps balanced cables, but as GMood1 suggests, is this really relevant to me, with my setup. Well, I guess the proof will be in the listening. I'll send my observations when I have a few days of listening. Thank you. |
I have my passive attenuators are inside my mono amps, the attenuator is a couple of inches away from the input tube. I have good dynamics but my old SS preamp was much more dynamic! I guess thats what you loose with passives against active. I used to have an outboard attenuator box and did not notice a lot of difference when I put the attenuators inside the amps. I did notice a big change when I used all resistors inside, I guess the big change was due mainly to resistors against the alps pot, more than the lenght of the cables... Pubul57 please let us know how you do with the Placette passive and the changes you notice against the CAT, this is very important to me since I still have the bug for an active preamp. |
Jsadurni, you should be fine with a passive..just make sure the next one is a TVC not the PLC with autoformers. I watch movies with my TVC..no shortage in dynamics.Also from what I've read the PLC with autoformers doesn't electrically isolate input from output like a TVC. This means you'll have less noise filtered with the PLC. Give it another go..before you throw in the towel. Good luck |
"Also from what I've read the PLC with autoformers doesn't electrically isolate input from output like a TVC. This means you'll have less noise filtered with the PLC." In theory then, that would be a good thing. FWIW, the task of the volume control is *not* to filter noise! I would suspect that there are other reasons for a preference. |
"FWIW, the task of the volume control is *not* to filter noise! I would suspect that there are other reasons for a preference." Yes I agree, I suppose it is how one looks at it. I'm not designer like yourself,but don't you use something inside your equipment to filter noise or keep it to a minimum? Capacitors or something? If you did then your amplifiers or preamps would also do the job of lowering the noise floor..correct? This wouldn't be any different from a TVC having the same ability would it? Having preferences is fine..I wouldn't have it any other way. I'm thinking seriously of buying a tube amplifier to run with the TVC when the moment strikes. One day I may want to mix it up a bit. It is always good to have different types of gear to swap out, when you want to hear music in another light. |
Can't get any better match between source nd amps than that, Jsadurni. "If it ain't workin' for ya, it ain't workin!" The only other question is what type of interconnects are you using and how long are they? I've heard that capactance and inductance, or the relationship between both, can be a HUGE influencing factor in the performance of a passive pre. From your August post here, it seems you have settled on short speaker cables and longer interconnects. That's what has also worked best for me. |
Still waiting, but maybe they'll arrive today. Atmasphere. let me ask you a question. If you could design a passive preamp, choose an appropriate source with just the right output impedance, select the cabling to be used (for appropriate electrical properties- and lenght)and they were feeding one of your OTLs or some other quality 100KOhm load - that is you could optimze the variables that determine successful versus unsuccessful implementation of the passive approach - could you conceive that a passive, minalmist approach might work better, sound better than an active, any active preamplifier. I would accept that the passive might not be as flexible, be more fussy, and may be less universally marketable. |
Unless I missed something, all of this talk of transformer vs. autoformer is pure speculation. I don't see where anybody posting has actually compared. Neither have I, but the link I gave to Intact Audio has an active forum with people I know, and who's ears I trust, who's passion is transformers and inductors, and FWIW they say there is no contest; an autoformer is clearly superior to a transformer when used as a volume control. I don't see this as a drawback as the issue with DC is no different if you use a resitive voltage divider of some sort. |
Darkmoebius: Yes very short speaker cables I actually have built a pair to my flavor mixing copper and silver transformer wire, right now I think I am missing a couple of copper strands to give it more body. The ICs are Gabriel Gold bought here in Agon, I also have Nordost Blue Haven but they are a bit forward and shy on bass, I tried Siltech SQ80 and they were too dark, Black Mountain were too light..Gabriel mixed good in my system, 1 meter between DAC and amps. 4 inches one strand kimber blue (from 8tc) from the attenuator to the input tube inside the amp :-) I got the PLC partly because I got a good deal and because I heard better reviews of autoformer vs transformer...since I got the perfect setup for passives I might give the transformer a try, probably the Promiteus Audio since they are affordable. (say against th 6.5k for the AudioConsulting) Atmasphere: I find Pubul57s question very ineteresting also, If you could design the perfect source-preamp-cables for your amps, would it be passive or active? Thanks |
I came across Dave Slagle via Thom Mackris at Galibier Design. Thom was very impressed with the autoformer Dave built for last years RMAF. Lynn Olson recently reviewed the Monarchy M24 DAC/preamp and used the autoformer in the review system. He gave the combinaton a glowing review. I certainly give both these gentleman a lot of credibility. I myself own an S&B TVC custom built for me by Kevin Carter. I have heard the Sonic Euphoria and did not like it as much as my TVC, but when I'm at RMAF this year you can bet I'm going to see what it will take to get my hands on a Dave Slagle autoformer. Resistor-based passives, TVCs and autoformers all have their place. Just like anything in audio it all comes down to a well thought out and executed design. There are many fine flavors to choose from and that what makes this hobby fun for me. |
I wasn't dawging the PLC..only pointing out. One shouldn't confuse the two. Whether one is superior to the other is in the ear of the beholder. Hey Jsadurni..if the Promitheus doesn't work out for you. I'll buy it from you for what you paid for it. I already know the out come..once you get it, I'll have to pry it from your cold dead hands!LOL Good listening |
Herman wrote: "I don't see this as a drawback as the issue with DC is no different if you use a resitive voltage divider of some sort." But, both Autoformers and resistive pres are significantly different than a TVC in that regard. Galvanic isolation means that no DC will pass through the TVC at all. Of course, I think most sources have a capacitor near their output specifically for DC blocking. Anyway, it's best to absolutely sure that no dc is being passed by all sources before making that very expensive leap of faith. Another major TVC advantage(if needed), is that they can easily convert single-ended signals to fully balanced for driving very long XLR cables with little signal degradation. A big advantage when your equipment rack is on one side of the room and amps next to the speakers on the other. |
Actually, I have compared autoformer vs TVC. It's really simple when you wire your own. Just use one side. To be honest, it was a mistake and was supposed to be a mute switch. Being a switch, I could compare instantly. I thought the difference between the two was almost negligable. The autoformer did have a slight advantage in the bass but the ability to use both RCA and XLR inputs swung the vote to TVC. I've also had the opportunity to compare silver versus copper windings with a friend's TVC. Silver worked better with tube amps and soft domes but I preferred the copper with SS and ribbon tweeters. Odd, since I've always favoured silver or silver plated IC's. Over the years, I have also tried passive pots and attenuators in various configurations but I haven't tried the Placette. There was a big difference between pots I tried and a simple resistor in line. Don't ask me why. I have never directly compared the attenuator to the TVC. |
The Placette has arrived. I don't and won't rush to judgement - I plan to A/B with the CAT for 2-3 weeks. I can say that it is certainly competitive, and on first blush I think it might be better. I do not notice any diminishment in bass or dynamics which I was looking for. It is quiet. The music seems to be very clear and localized - that is I hear clear delineation between the location and source of a sound. Microdymamics are fantastic, instrumental or vocal inflections (what I think expresses emotion)is superb. I impressed that at this point I can't say the CAT is better, a pretty good sign for a $1000 unit - true, there is no switching facilities and can't drive long, high capacitance cables - but you know, you could defintely live with this thing in a high end, single source system. To say the least I am impressed. I would certainly recommend that this piece be auditioned and compared with top of the line active preamps (the CAT has to be one of the better ones). It is making me awfully interested in hearing Placette's no-gain active - I think Placette's desinger is on to something, and it might be that Vishay-based volume control . Well, I'm going to listen to this for a while, but darn it sure has made a good first impression. |
The issue of DC on an output would not be solved by any of these controls, but I should nave been more clear. My point was that even though DC on an output would be a problem for an autoformer, this didn't strike me as a real life problem since resistor based volume controls would have the same issues. In the first place there shouldn't be any DC on the output of a commercial source since many amps are DC coupled and it would cause severe problems. If you are doing DIY like me then it is something you have to decide for yourself. In any case a transformer would also be a bad choice for a source with DC sitting on it's output. The way to do it (as mentioned) is a cap to block the DC. A transformer would short it to ground, not good. There are some designs such as either a parafeed output or an interstage transformwer acting as a plate load with a tapped secondary that would do double duty; DC isolation and volume control, but then you have to worry about the varying load on the output tube as you change the volume. Nothing is simple it seems. |
"Yes I agree, I suppose it is how one looks at it. I'm not designer like yourself,but don't you use something inside your equipment to filter noise or keep it to a minimum? Capacitors or something? If you did then your amplifiers or preamps would also do the job of lowering the noise floor..correct? This wouldn't be any different from a TVC having the same ability would it?" In the audio path, we do everything we can to insure bandwidth. OTOH, we do all we can to prevent noise from the AC line from leaking in. The two are definately *not* the same! The idea that a volume control would filter noise of some sort is to say that it is really a tone control as well. In the world of high end audio, the idea is to get away from tone controls so as to get to the truth of the matter. |
"Still waiting, but maybe they'll arrive today. Atmasphere. let me ask you a question. If you could design a passive preamp, choose an appropriate source with just the right output impedance, select the cabling to be used (for appropriate electrical properties- and lenght)and they were feeding one of your OTLs or some other quality 100KOhm load - that is you could optimze the variables that determine successful versus unsuccessful implementation of the passive approach - could you conceive that a passive, minalmist approach might work better, sound better than an active, any active preamplifier. I would accept that the passive might not be as flexible, be more fussy, and may be less universally marketable." Here's the problem that passives are up against (if done my way). 'My way' is to eliminate the interconnect cable as a sonic variable so that any cable will work as well as any other (right now you have to go balanced to do that BTW). Anyway, to achieve the above for me would mean a very low resistance passive system- probably about 100 ohm control would do the job. This is a challenging impedance for a CD player to drive with low distortion and enough voltage to drive the power amp. Please keep in mind that I am expecting the system to be immune to the effects of the cable. You are not going to get this if the value of the passive is much higher than that. IOW, its impractical with current CD players and phono sections. |
"In the world of high end audio, the idea is to get away from tone controls so as to get to the truth of the matter." OK let's look at from another perspective. Since it's the goal of high end to get away from tone controls.. This will leave a lot of members here in the dust. Essentially every component is a tone control. All the way done to the tubes used in a selected piece of gear. How will we ever get away from tone controls? When every piece of gear is basically a tone control? No matter how High End you go...there will always be those darn tone controls. |
Hi Gmood1, I don't agree with your statement for several reasons, not the least of which is that equipment exists that seems to lack 'tone control' qualities and in fact is able to fool jundiced audiophiles. This is a forum for high-end, not mid-fi so we won't be leaving too many 'in the dust'. Finally, we're getting off-topic, but if you would like to discuss this further perhaps we could start a new thread? All the Best! |
Ken Stevens, the designer and manufacturer of CAT equipment, once told me that a parts manufacturer (I think they were resistors)asked him what "flavor" of sound he wanted from the resistors (warm, bass-oriented, etc.). That is, these parts could be used as "tone controls" - Ken's answer was I want the flavor of water. The sales reps was a bit confused, but I think Ken's goal and Ralph's goal seem similar - "get away from tone controls so as to get to the truth of the matter". Which gets back to the passive/active debate - can an active line stage ever get as close to the "truth" as a passive (minimal flavor, clear as water) implemented in a properly matched "system". I still think that the active approach is probably necessary for some of the reasons mentioned by Ralph and the need to actually sell this equipment into a variety of listening envrionments and matching equipment. |
Mr.Sphere true this is a audio site, hopefully for all not just what's considered High end because it cost a certain price. Maybe we're thinking the same thing just from different perspectives. I like absolute transparency not at the expense of being musical. I want to hear every change in the system. When I change tubes in equipment,cables,dacs,etc.. I want to hear it. I have achieved this without breaking the bank. Every system has a flavor to it from the mixing of the components. Changing one piece will change this flavor. I personally find it far fetched that any componenet doesn't have a flavor. If there wasn't a flavor for each component, we would all listen too and like the same equipment. I haven't heard a capacitor that sounded the same as another. I haven't played with them all..but quite a few. The same with tubes..come on..I know you have a favorite type tube for your equipment... most designers do. Give up the goods!LOL Just look at the post here on the GON and what people ask for. It's not the sound of water I can guarantee that. Maybe we should start another discussion. I like keeping you busy. ;-) All the Best |
Man, it's nice to see a reasonable discussion about this topic that doesn't plunge into the ditch with personal attacks and such. I also like the insight into the design philosophy of 'sphere. Since I happen to agree, I'm now inclined to give their stuff a listen. Obviously off topic, I've often thought that speaker companies could simply describe how they voice their speakers and save me a lot of trouble. I suppose this could be said with design philosophy of almost all gear. Save the marketing jargon and tell me what you consider important in the design. |
I tried the RVC as a remote volume control for the CAT, the CAT sounds the same, or at least I can't tell the difference.I think the RVC is worth the price just as a remote volume control with no apparent harm to the CAT. If you own the CAT you know you need/want some finer volume settings. This RVC has me wondering about their active linestage. I'm thinking that much of what I like about the Placette might be attributed to the volume control itself (and address some of Atmasphere's concerns or issues with passives) Who has made the change from the passive Placette to the active? What were your impressions? How does this active Placette compare with great tube units (CAT, Joule, Atmasphere, First Sound, BAT, CJ, Lamm, etc). I'm especially interested if you have made the move from your beloved tube models to the Placette, and have had no regrets. |
Started with a Bent Audio NOH (passive TVC, silver) and upgraded to latest Bent Audio TAP (TVC, silver). As Fazoid has observed, it was the best move I have made. When I recently swapped an active preamp, I knew just what made the TVC so special! If transparency and sonic purity is what you desire, the TVC is the way to go! I hear that the Promitheus TVC (Malaysian manufacture) sounds really good (I have no doubt) and comes with an attractive price tag. For those hesitating, it does not cost much to give TVCs a try. Once you are convinced, the convenience of the Bent Audio TAP (not to mention its beautiful futuristic look) is worth considering. I hear that Music First has entered into a deal with a Bent Audio to carry the TAP under the MF namesake. I also believe that John Chapman (real gentleman and genius, creator of TAP) is still offering the TAP under the Bent Audio badge for a few more weeks before the price goes up under the MF badge. Denjo |
Pubul57, I have in my system the Placette dual active line stage that replaced a Mark Levinson reference 32, that cost $10000.00 more then the Placette! However, it's performance was head and shoulders better then the ML-32. The Placette was among six preamps, three were SS and three were tubed, that I auditioned before chosing the Placette for my system. It's a great preamp and I believe a bargain for $4500.00. If Guy sold his preamp through retail salons I believe the cost would be around $7500.00 to $8500.00 with the overall markup ratio. Another Gon member finally found what he considered a better sounding preamp, the darTZell, which sells for almost $20000.00! That's quite a compliment considering the price difference. A final thought, I believe that the active line stage is about 20% to 30% better in its sonic performance compared with the passive. You also might want to go back to the review that was in the Absolute Sound, that gave the Placette a "golden ear award", I believe it describes the sound of this preamp with great accuracy. |
I spoke to Guy about my setup and I think it would be of interest to Merlin Speaker w/BAM owners. I'm feeding my DAC to the Placette RCV and that is connected to the BAM (Bass Augmentation Module running in battery mode)which is then connected to my amplifiers. The BAM has a 40 Ohm Input Impedance and a 100 Ohm Out put impedance and can put out up to 8-9 volts. Guy felt that with the BAM in my system, there would be very marginal improvements, if any, if I were to use his active. Apparently the BAM does a lot of good for this passive approach, which explains why I like it so much. My observations therefore might have to be taken in that context, although there are apparently other users of the Placette passive that like it quite a bit without the use of a BAM. I would say this, if you own a Merlin speakers and are using the BAM, you really owe it to yourself to try the RVC (he gives you a 30-day trial). I think you will be suprised by the results. |
Pubul57, the tube preamps were the reference Lamm, Hovland HP-100 and Audio Research's reference before the Ref 3. What you might find interesting is that I was discussing preamps with a dealer who is a tube "maven" about what would be worth auditioning in his opinion. When I asked him what preamp he uses in his home system, he laughed and said the Placette active line stage! He believed that it offered the best performance, even if it was not a tube based linestage. He also shared that all of his clients that auditioned the Placette kept it and traded in their tube preamps. |
Teajay, that is a very impressive lineup of tube preamps. I think the CAT is up there too. I started this looking for a passive to try, but what has impressed my is the Placette focus on trying to build the "perfect" volume control. I'm going to continue to A/B with the CAT for a while, but either way I think this RVC is a keeper, especially at $1000. |
Pubul57, Wait until you get 100 hours or so on the Placette, bet things just get better and better. Take your pick as to whether passives actually "burn in" or it takes a little time to notice all the extra fine, subtle, details that get through. But, you should be able to notice things that never came through in recordigns before. Enjoy! (and let's know how things develop) |
Atmasphere: I found that the resistance of the control changes the sound A LOT, huge changes and that worries me, I have been closing in on the best value for my system and I have always been going lower, now I am using 1k, the diference from 1k to 1.2k is big, mainly the instruments get more body and weight, dynamics are also better. With 10k there was no dynamics, the snare drum didt really move me it sounded like a stick...going lower its becomes more of a drum, fuller sound and it begins to move your belly when it hits (thats what I like!!) With my active preamp I had huge dynamics and almost no transparency loss...the passive is more transparent and I have almost huge dynamics..If I had never heard the active that way I would be very happy with my passive right now. I am going to try a 800 ohm control and see what happens!! I am also using AN tantalum resistors since they give out a fuller body than the caddocks or vishay I tried. I talked to Guy from Placette and he didnt recommend a 1k attenuator, he does not make it either...so I will have to get the active Placette then! If its 20 or 30 % better more transparent and dynamic its does sound pretty good...does it come with a phono section also? |
I posted my thoughts early in this thread and have been following the very constructive discussion. i read somewhere in the thread that the power supply for the Placette passive RVC does not (or should not) benefit from a quality power cord. that was also my thought 'originally' too. but i did experiment with it and to my great surprise i did hear a bit lower noise floor with the little power supply connected to a good power cord. i don't have my RVC any more and can't remember exactly how it connects....but until you try it don't 'assume' anything. my opinion is simply that the Placette is sooo damn transparent that any improvement jumps right out. Guy from Placette told me at one point that you can 'stack' 5 RVC's and compare them to one RVC and they sound identical. i believe it. try that with any other attenuator. |
"The same with tubes..come on..I know you have a favorite type tube for your equipment... most designers do. Give up the goods!LOL" Its true. I prefer the tubes that I do because I can get them to be neutral. How neutral? Neutral enough that the state of the art has to evolve to hear the colorations. Even then we find that changing things elsewhere (power supply, wiring, coupling caps etc.) will often deal with it (in effect we still are not hitting the limits!). I agree that all things make a difference, and I know that creating a system around a coloration will not work in the face of creating a system around no coloration. Synergies in effect do not work. |
I know that creating a system around a coloration will not work in the face of creating a system around no coloration. Synergies in effect do not work. I agree that it is a worthwhile goal to build a component that is completly neutral (straight wire with gain) but since we are all using different speakers that in relative terms are all highly colored, couldn't you end up feeding a speaker with a completely uncolored signal and still have sound that is crap. As long as we have highly colored speakers further complicated by room interactions, it seems we will always be tweaking the system to color it in a way that compensates for speaker and room colorations. |
Well,it is official, I love the Placette RVC - in my system it works. I'm finding it hard to justify keeping the CAT for my system and my needs, I've put it up for sale - don't get me wrong the CAT is one of the great preamplifiers,and can obvioulsy do soemtings the RVC cannot (phono, source switching, drive any cables into any loads, etc) and deserves its following, but for single source CD with the right impedance/sensitivity/blah,blah - the RVC is awfully good, especially at its price point (I'm not saying it is good for the price, it is good period - at any price). Of course, I'll be thinking about the active Placette, well, maybe after the CAT is sold. |
Congatulations Pubul57!! As long as we are making announcements I would also point out that my dynamics quest with the passive preamp is over, now I got the dynamics of my previous SS preamp and the transparency of the passive, tweaks helped a lot for this, Ribbon power cables, 2 inch Spruce Wood bases on all my gear, and biamping!!! I now use my passive preamp to drive my mono amps and a Subwoofer....amazing! Best |
