I have a re-capped Conrad Johnson Premier 140 amp. I use the KT120 tubes and have a nice Amperex in the 6922 position. I have been driving it with an Airtight ACT3 ($7550) I have tried all sorts of tube from Brent Jesse. In finally landed on a great Amperex in the 12AX7 position and Mazda in the 12AU7 slot. I though I was done. Very clean, balanced, totally non fatiguing. I was very happy. Then a friend mailed me a Khozmo passive preamp. The thing new cost about $500. Outside of the volume pot clunking around when you turn it, I just cant match the presentation with my Airtight. Turn on Behind Blue Eyes by the Who, and the vocals + guitar make you want to cry. It is so fine, airy and full of tone. This may be in part that I know really realize what a wonderful amp my CJ is. Bass, it is all there for me. Much more clear and tight. Even when I put the Teefunken and RCA back in I could not get the clarity. Also, when I first plugged the Khozmo in, I though it did not work. There was absolutely no hiss coming from my tweeters. Black. That is until I turned the volume and music came forth. If you have a nice tube amp, you don't need an active pre. It just adds more tubes and headache. I have not attempted to sell my Airtight yet. I am going to try some other passive. I just don't like my volume clunking all over. Plus I am thinking remote might be nice, so Tortuga? Anyhow, don't discard the idea of passive. If you have a nice tube amp, give it a try. |
I use what is in effect, a clone of the MFA Baby Reference, built by a Hungarian gentleman. It uses the same transformers as the Baby Reference. It feeds into the ARC reference 75 Power amp and is very impressive. I got the idea from a HiFi+ review of the ARC 75 with an ARC LS27. The reviewer had a baby reference to hand and felt the Pre's were different not better than each other, the passive more air and refinement and the LS27 more slam.
I briefly heard my new 75 with the dealers Reference 3 pre, when it was delivered. Too short a period for proper comparison, but I agree with the HiFi+ reviewer and prefer my Pre. It cost by the way, £950, which is less than the current price of the S&B transfomers, so all in all a good deal. |
Take a look at Tortuga Audio and the passive they have come up with. All the reviews rave about it. I bought a board recently to start a DYI project to try it out. |
The Goldpoint SMD resistor passive and Endler Audio Stepped Attenuators I have here display a purity of sound that is very nice at first, but as time goes on you realize there is a level of dynamics and tonal density missing, compared to active preamps. Resistor based passives are also quite sensitive to impedance matching and can sound terrible in the wrong set-up.
Transformer and autoformer passives are said to resist this trend, and can even provide 6dB of gain. The Music First Audio preamps fall into this category.
I have to agree with those who like buffered passive preamps since the buffering helps prevent losses from long interconnects and impedance mismatches, and seems to restore dynamics and tonal color. My McCormack TLC-1 has been completely tricked out by SMc audio and is essentially a buffered passive that achieves 6dB of gain through Lundahl output transformers. This is the best preamp I have heard out of many, including several approaching or exceeding $10K. |
In my experience, passives with Stevens & Billington transformers are very nice. The Money (oops, sorry), Music First Audio preamps are exceptional. That's quite a claim you make about the Baby Reference, Drubin. I'd love to hear one in my system to do an A-B. I only have experience with their copper (which is the classic, I think), and Silver models. |
I've tried many passives over the years, including Bent TVC and autoformer, Lightspeed, and both passive and active Placette. Then I tried the Music First Baby Reference. It's head and shoulders above the rest, at least in my system and one other I tried it in. The Placette Active (my first passive, wish I'd hung on to it) was also very good. Actually, all of them were very good, but not at the same level. The Lightspeed is quite a bargain. The passives from Tortuga look promising.
I use short interconnects only (1.5M at most).
I have tried a number of active pre-amps and do "get" the argument for them, yet I love the transparency of passives. Actives I've tried from Ayre, Rowland and Klyne have all been major disappointments. I think you must have to spend a lot more, and I haven't done that. A Gamut preamp I had when I had a Gamut power amp was superb. The First Sound I had many years ago was quite wonderful, but didn't offer remote. Your mileage may vary. |
There is a Placette that popped up on the Club Polk website for $600. |
If you go passive, and AS LONG AS NUMBERS JIVE (in/out impedances, voltage sensitivities, interconnect length/capacitance,etc).....Lightspeed. |
Re the McCormack TLC-1, I had one for years and while the sound was very good, the sound did not compare with the sound form a Reference Line Preeminence One that I later bought. I suppose that's why Steve McCormack introduced the Deluxe version (which I haven't heard but which I assume is better.) |
I agree with Tim, I feel a buffer is the best of both worlds
I had a lot of pre's, once I went with the Dodd buffer it was
a good change. Now have a Wyred 4S STP/SE is a buffer and also has gain (which I never need), wanted to try balanced connections and it is another improvement |
How about a used McCormack TLC-1 or TLC-1 Deluxe preamp? I'm surprised McCormack or Mod Squad passive preamps have not been mentioned. Very good quality build and re-sale value, if bought used, is retained. |
Jgiacalo,
I have a First Watt B1 buffer preamplifier that I'm no longer using. It's an outstanding piece that is totally transparent and you don't have the impedance issues to worry about. Send me an email and maybe we can work something out.
Tim |
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Atmasphere has it right. You have to be very careful about the impedances you are working with (interconnects, amplifier) or you can actually make things worse with a passive "preamp". I once had a preamp that had both active and passive modes, and the passive mode caused very noticeable rolloff of the high frequencies, just as Atmasphere has described. If you really want a passive preamp, try it first in your system before you commit to spending money. |
Over the years I've had 1k passives all the way to 22k passives and many in between and while passives do many things well once you switch back to an active pre it all comes together. You should give a passive a try but in the end you will find a well made active will give you the most satisfaction, I know I did. |
The Promethius TVCs are very good. I owned the Ref 4 and still have the top of the line statement, although its been bumped out of the system by the superb Coincident statement line stage.
The Promethius TVCs are a lot of bang for the buck. |
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Channel Islands Audio VPC.3 ,$300 new! |
I think the luminous audio axiom II is a nice product..especially with the upgraded Caddock resistor..when ordering they will ask you questions about your source, speakers, and amp so they can fine tune it to your setup.. not a huge investment either..even if you go with their Walker mod package |
Jgiacalo: You are right, a passive volume control will give you the best transparency and dynamics if your setup is right, your 252 poweramp only needs 1.6v for full output and most sources give out over 2v, so this is a great match, as you can see there is no need for extra active preamplification.
Your source will determine if it can drive the combined load of a passive and the 10kohm input impedance of your 252, if you tell me what your source are brand and model I will let you know if all is good for you to go ahead.
Don't listen too knee jerk sceptics who dismiss passives without looking to see if your system is compatible for one, because if it is you will never go back to active preamplification again.
Cheers George |
..whatever the reasons, I tried them a few times, and they were all way less good than my active preamp. |
You might be surprised to learn that there is not a lot of difference between really expensive and really inexpensive passive controls, when used in some type of outboard box.
You will find that the things that play the biggest role in the sound are the actual value of the control and the interconnect cables themselves.
A high value (100K) can interact somewhat with the input impedance of the amplifier and may cause high frequency roll offs. Conversely, it can also interact with any output coupling capacitor that might be in the source, effectively increasing the cutoff frequency (reducing bass impact).
A lower impedance like 10K will have less high frequency interaction, but will still interact with the coupling cap in the source, and some sources may not be happy driving such a low impedance load.
So you have to be really careful with your setup, and you must keep your cables short, no matter the brand or price. A properly designed and built active line stage can overcome these problems but it is a statement of the poor state of line stages that so few actually bring home the bacon, hence the on-going debate about which is better- active or passive. IME if you do get a good line stage there will be no looking back. |
