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In Reply to: RE: Ranking Of Vintage Tube Preamps While We Are At It posted by rosendds@frontiernet.net on December 12, 2014 at 05:26:15
Dave
My favorite is the Fisher 400CX2 after upgrading with fresh caps and rebuilding the DC filament supply.The Mac C20 is also very good as the Marantz 7C and the ARC SP3. The Mac C22 and the Citation one both have great phono sections but I don't care much for the C22 and the Citation one can load just about any cartridge but I wish the line stage had a bit more dynamic muscle..The Citation four is another one to consider.
"
Follow Ups:
The best (stock) tubed pre I ever heard was an Audio Research SP -6B. I suspect that the stock SP-8 and SP-10 are better, but I've not heard them. I know that the SP-9 in all iterations was quite inferior. Regardless, I need tone controls, so if I ever sample an ARC again, it will probably be an SP-3 (x).
In their stock forms, Mc C20s and C22s were largely indistinguishable to me. I can report that a stock C22 (from the '60s) had a tolerance in RIAA equalization inferior (larger) to what we would expect today -- i.e., a larger error. Perhaps more important, the physical arrangement of various internal parts in order to deal with the fancy front placement of controls greatly diminished stereo separation -- John Curl would cringe! Both issues can be addressed, but the latter takes hours of measurement and soldering by a very dedicated tech. Once they are addressed, however, the improvement in sound-quality is substantial. Because my C22 was not upgraded until a few years after I heard the Sp-6B, I cannot say for certain which I'd prefer today.
A properly maintained PAS-3x is superior to an SP-9 but inferior to the SP-6B and upgraded C22.
Jeremy
Jeremy
I have a C11 and C22 and the C11 is electrically identical to the C22 and I did every upgrade I could to the C11 and I only heard a marginal difference from stock..The C20 really rocks with upgraded capacitors but the C11 and C22 just don't seem to roll.
"
Michael:
Thank you for mentioning that and for giving me a chance to explain. May I say that the old, very stock (and possibly disintegrating from age) C11, C20, and C22 that I once compared (many [35] years ago, but my ears were better then -- maybe a compensation for old memory) sounded pretty similar to me -- all better than any solid state. But I must add that the comparison was not at my house on my equipment which latter uses(d) Spendor BC3 speakers that tell one (or at least told me always) when a new device I was slipping in upstream changed the sound.
My "tech" was not merely my best friend but also the most brilliant audio engineer I ever met.
That he swapped my C22's resistors and capacitors for modern ones goes without saying, and he made other changes as well -- to wit, redesign of the RIAA equalization; still point-to-point wiring but much flatter (closer to RIAA spec) than originally. He also made phono 2 10 dB lower in acceptance than phono 1 (the Mac original) to accommodate a wider variety of cartridges and step-ups.
All that was sonically better to me, but by far the largest improvement in sound quality came at the end: my friend had already discovered that connections from the front to the back panel of the C22 had been made for convenience re the front-panel fancy control layout. He began seriously to measure separation from input to output and discovered that separation was compromised all over. A bunch of that separation-loss was due to "capacitive coupling" = "stray capacitance" between channels. Using a multimeter, my friend measured separation between input and output through the whole C22. He fixed as many as possible exemplars by soldering-in metal barriers wherever one could measure the problem That took him days-to-weeks, and I rightly paid for that, notwithstanding our friendship. Years ago, I mentioned all that on this forum and a McIntosh tech ("Ron C" -- Ron D?") replied, "That must have been a really good friend". Indeed!
So, MIchael, I do not suggest that any of the 3 pre-amps is the best. But I do assert that if you re-wire as I have had done, the race may be very different.
Sometime in the recent past I raised the issue of separation with an inmate I greatly respect -- John Ellison. He opined that separation is, lately, not an important issue. Let me report that the stereo separation on my stock C22 was as low as 6 dB at some settings of the volume control. Today, it is nowhere less than 56 dB. The sound is greatly different.
If I've not usefully addressed your issue, please let me know and I'll try again.
Jeremy
Hope that helps, but if not, please let me know.
I find it amusing that you, Mike and Jim McShane improve upon the work of the likes of Sidney Corderman and Stew Hegeman. Really.
I am pleased to have provided amusement!
BTW, you should see what I've done to my model T -- it rides and handles more like a Honda Accord now, and it is not black! Henry, too, must be rolling in his grave laughing.
Jeremy
How about a picture. I am fond of hot rod Model T's!
Dave
Apologies, Dave: I am digitally underequipped (missing some toes) for that. Let me just say, though, that long hours and much measurement by my dedicated tech have produced something perhaps best called a "Fonda" -- I'll leave it to your imagination. But, you know, it's faster than stock, easier to start, with a more responsive engine and transmission and better mileage, and it's not black!
Jeremy
Given that a stock Model T has a 20hp flathead 4 cylinder that started with a crank, and had a 3 speed (2 forward, 1 revers) transmission, that leaves a lot of room of improvement!
Dave
Dave: My son asks that I also explain (he's checked) that we are out of metal plates for our daguerreotype machine. A lame excuse, sir, a wretched excuse, but mine own.
Jeremy Shakespeare
No, that's a good excuse. It's not like you can just pop down to the local CVS ...
Dave
The Citation 1V wasn't on the list but it is mentioned at the bottom along with the MX-110 and uppgraded PAS3x.
Sorry, Dave: I forgot also to mention the MX-110 which I would rate higher than any PAS-3x, and higher also than a stock, 1960s C20 or C22..
Jeremy
"Citation one can load just about any cartridge but I wish the line stage had a bit more dynamic muscle."
The Cit. 1 uses an anode follower (see graphic). It has some "stones", but not as much as a cathode or source follower. Adding another tube to the chassis is out of the question, but adding "sand" should be doable.
The presence of a coupling cap. rules out DC coupling an enhancement mode source follower, but depletion mode FETs can be self biasing. To avoid problems with FET reverse transfer capacitance, a cascode seems in order. A candidate for this job is the TO92 case DN2540N3-G.
Eli D.
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