Ig316b, I would agree with you about the TLC-1. I borrowed a CJ PF1 solid state preamp to see if this active preamp would actually sound better than the TLC-1. I gave it 24 hours of continous operation. It was a bit more dynamic but the TLC-1 sounded far better in the midrange/vocals but with a smoother (grain free) top end, also transparency was far better. Now this is the stock TLC-1, I can only imagine how good the TLC-1 would sound with the ultra upgrades. You already know that I like the McCormack products and still own one his amps as well.
Who is using passive preamps and why?
Seldom has there been any discussions on passive preamps in the forums and although my experience with them has been limited I have found them so far to be very enjoyable and refreshingly different. They seem to fall into their own category, somewhere between solid state and tube. Finding a preamp that is satisfing has been difficult. Some active solid state preamps can be very good but they seem to inject grain to some degree in the upper registers and some tube preamps are not too far behind. So far I think they should at least be matched up with an amp that has sufficient gain which is often overlooked. Which passives are you using and with what amp? Why do you like them?
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03-16-10: Phd TVAD, you have the ultimate preamp! The VRE-1 is very spendy but beautiful and one day I will own one even if I have to wait. Phd if you would like a preamp that is as Mr. McCormack puts it right up there with the best might I suggest you try the McCormack TLC-1 with the Ultra upgrades from SMc. I had this upgrade done on my TLC-1 Deluxe and the difference was night and day. With the stock TLC lack of dynamics was not a concern (as far as going from quite to load passages), I had that in spades with the pair of DNA-1 mono-blocks, what did concern me was the lack of drive in the base region, it seemed like the slam was lacking when compared to the active output of my Micro Line Drive with Gold upgrades. At one point I had considered getting an ALD-1 for a comparison to see which I would prefer. The TLC Ultra completely eliminated any of these concerns. I guess this could be accounted for by the fact that to use the step attenuator that Steve builds, he has to convert the passive output to a buffered output. I had tried both the passive and buffered on the stock TLC and it wasnt quite the same. The TLC Ultra is leagues ahead of the stock TLC, so much so that you start to question what else in your system could be hindering the sound. Anyway just a suggestion and food for thought if your interested. |
I completely agree that some components demand that you use an active preamp and such systems are capable of superb performance, but I think perhaps you missed my main point. The main point of my post was that it is not the passive volume control causing the problem some experience, it is trying to use it with the wrong components. Let me try again. ALL systems consists of some source of an electrical signal, usually a DAC chip or a phono cartridge these days, followed by a series of active devices that eventually amplify the voltage to a level sufficient to drive the speaker. At some point in this chain of amplifiers you must include a passive volume control. To keep it simple let's concentrate on a system that only plays CDs. The most common way to do this in a high end system is to have some amplification inside the source which amplifies the DAC chip output up to around 2V. That feeds an active preamp which may or may not amplify the voltage but contains at least a passive volume control and a buffer. That is followed by an amp that further amplifies the voltage and can supply enough current to drive the speaker. There is nothing magical about putting the volume control where it is. It could be in the CD player, it could be at the input to the amp, or if the output of the CD player is robust enough and the amp input is benign enough so the buffer isn't needed it could be put in a separate box between the CD player and the amp which we call a passive. My point is if you blame wimpy sound on a passive it means you don't understand what I stated above. How about this? I don't have a preamp of any kind. I'm using Pure Vinyl software which controls the volume in the digital domain using 64 bit math. I modified the source so the DAC chips are connected directly to the input triode tubes of my amp through a 1:1 transformer followed by 2 more triodes. In case you are interested they also just release a version called Pure Music which doesn't include the vinyl functions. Check it out http://www.channld.com/pure-music1.html . |
Herman, I think there are plenty of people that know perfectly well how to match a passive between their source, cabling and amp, and even when getting all that right still prefer an active preamp. Obviously in the wrong system a passive preamp will stink, but we are not talking about something so gross as that. One has to wonder what it was about Albert's system that he preferred the DarTzeel to his Placette? On some level it seems to make sense, how could all that sophisticated electronics (and complexity)used to amplify the signal only to have to attentuate it yet again possibly be as pure as leaving the signal alone? Well, it seems that for some people an active will do just that, and not just with an $18,000 preamp. I still agree that with a good source voltage with low output impedance feeding a passive into a sensitive amp with high imput impedance it is pretty hard to beat a passive for SOTA sounds at a very affordable price. It is for many a very good option, but it doesn't mean others don't prefer actives to passives even under the best of circumstances. (I've had Placette, K&K, and Bent with Autoformers - all sounding wonderful, but I prefer my Joule and Atma-sphere preamps in my system). One must also consider that many may love sources and amps (and possible cables) that just won't well with a passive at all. |
Active preamps are for those who can't figure out what it takes to integrate a passive into their system,... While this statement does apply to some, I do think there are those out there that just prefer the sound/coloration of tube preamps or other active preamps for that matter. No harm, no foul. Right now I'm playing with a Berning Mico ZOTL as a preamp and do enjoy the sounds of the various 6SN7 tubes I'm rolling with it. I also enjoyed my time with a Jeff Rowland Capri. Overall, I still prefer both my passives, but I can see why some might just prefer an active circuit. Some passives include an active buffer stage to solve potential mismatch issues. The SMc VRE-1 and Pass B1 come to mind. Both are fine preamps and an alternative for those whose systems might not be passive friendly. |
Paul is correct. Those who dismiss them as wimpy and lacking dynamics and bass simply don't know what they are talking about. That may have been their experience with them but that isn't the fault of the passive, it is the fault of the people trying them with other components they weren't well suited for and not knowing enough about the principles involved to solve the problem. Hook up a high impedance source to a low impedance passive into a low impedance amp and you get wimpy. Do it right and you get world class sound. Here is the ugly truth about about preamps...the volume control inside all of them, active or passive, is a passive device. It is either an inductive voltage divider like a TVC or a resistive voltage divider like a potentiometer or stepped attenuator, but they are all passive. An active preamp adds a buffer stage so it mates well with a wider variety of equipment than the voltage divider by itself. If you choose wisely as Paul states, paying close attention to the source that's driving it and the amp after it then you don't need that buffer and you get glorious results with world class dynamics and bass. In fact, it is better than an active because you've taken out an unneeded gain stage. Active preamps are for those who can't figure out what it takes to integrate a passive into their system, their source can't drive the amp loud enough so they need more gain, or they simply are trying to use a passive with components they will never work well with. Yes, you limit your choices for other components but there are plenty out there that mate beautifully with a passive. Like I said earlier nothing has been said here that hasn't been said before. . |
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People that appear to have drawn conclusions about passives without considering the critical issues - the impedances & voltages involved - haven't drawn meaningful conclusions. A well-known member here could not find any active better than his Placette Passive until he got to the $18,000 DarTZeel. I believe he tried a great many. I think at the time he had the Placette most or all other components in his system were 10-20x as expensive as it. |
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Herman, thankyou sir for correcting me and pointing out this subject has been debated to death. Realistically I think that most subjects that have been put forth in the forums have been repeated over & over again. However there are some new products that have evolved that could be discussed & their attributes and possibly offer some insight to someone that is considering a passive. |
TVAD, you have the ultimate preamp! The VRE-1 is very spendy but beautiful and one day I will own one even if I have to wait. I understand that all the years of Steve McCormack's culmative knowledge has gone into the VRE-1. Even his earlier model the TLC-1 is not chopped liver but certainly not in the same category as the VRE-1. However I never thought of the TLC-1 lacking in dynamics especially when paired with one of his amps. |
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Phd, I once had a Placette passive preamp for several years after previously using active tube preamps, I got rid of it and went back to active tubes, why? Because I agree with some of what has been stated above, the lack of deep base, not nearly as dynamic, and everything started to sound the same IMHO. Also the amp to be used with one, needs to have a low voltage input for full output in order to match well with a passive. I have a Herron Audio VTSP-3 preamp which to my ears is musical, quiet and dynamic and it's tonality is as true to the instrument or voice as any preamp that I have heard or tried. I suggest that you try one before you make any decision to go passive. See if you can borrow a demo from a dealer because it does take time to break in. I do not think that you would be disappointed. All the best. Carter |
Have to agree with Herman, the topic seems to come up once a month. When discussing passives you need to break them out into a few different camps. There are those that use resistors to attenuate the volume, those that use transformers, and those that use autoformers (a transformer with a single winding). Within the resistor camp there is a sub group that used opto-couplers in the design, thus eliminating any effect the switch may have on the sound. While the benefit of a pure signal at a fraction of the cost of an active preamp is an ideal goal of a passive preamp. The reality is some cost more, much more. Audio Consulting is a good example. Not only that, but passives, while providing a high level of transparency, can induce their own coloration and sonic signature. One example would be Audio Consulting's copper and Silver Rock transformers. The silver wound sounding more detailed and transparent IMO. Another example were S&B transformers of which there were the MkI - MkIII series. I preferred the copper MkI versions of these transformers as there was just a touch of warmth added to the sound. Resistor colorations are also possible - Vishay, Mills, Caddock, Tantalum, etc. Then there are the switches. So all in all, while we hear how transparent and pure the signal can be with passives, there are some caveats to that. For me, the big issue is reduced noise. I also feel the level of transparency cannot be beat versus actives. If you have enough gain from your source and the rest of your system is passive friendly then a passive preamp may make sense. However, if you're someone who prefers coloration and what some will say is more "weight" to the sound (maybe its just another form of pleasing distortion), then I doubt a passive will be your cup of tea. Better to "tune" your system to you liking in other ways. In my system the passives I have/had are: S&B MkI TVC (custom built by K&K Audio) Lightspeed Attenuator (boutique unit built by George Stantschleff) Slagleman Autoformer Volume Control (prototype built by John Chapman) The S&B was used with the solid state TRL D-225. The other two have been used with VAC Auricle Musicblocs, VAC Vintage Williamsom 35/35, and now a Music Reference RM-10 MkII. All of these passives worked fine with the respective amps. |