The 1956 Radiotechniques are quite good in my experience as are the Brimar CV4003s. I didn’t think much of the GE Mil Spec 12AU7 / JAN 6189Ws. They’re fine, but to me not particularly special…
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For me it’s the Telefunken ECC802S or the Genalex B749. Both have the sound I look for, just slightly tubey.
Right now listening to a pair of Amperex 7308 PQ. Fantastic!
I’ve been pleasantly surprised by the new production Gold Lion 12AU7s. They don’t have me pulling the NOS Siemens 7308s I currently have in my BHK Pre. But, as I’ve posted elsewhere premium NOS small signal tubes are becoming scarce at any price and I’m convinced I need to find a new production backup. After a lot of experimentation, I’m ordering my second pair of platinum matched Gold Lions as my go to when I’ve burned through my box of NOS treasures. That’s how highly I think of those tubes.
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I don’t have your extensive experience with NOS tubes, but the few times I have recently, I have stayed with the Gold Lions in the BHK Pre Are you using the GLs’ in BHK 300’s?
Shameless Plug for anyone that does not own this wonderful preamp:
See my ad in PS forums classified section for new unused black BHK Signature, with extras…
Thanks;
Tim
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Just ordered a pair, will report back.
Do you have a link for Brent Jesse’s website, or contact info? Would like to order a set of the Raytheon Baldwin 12au7s. Thanks.
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Gary
If you want to just try a pair to see if you like them then try these. I’ve bought multiple sets of tubes from him over the years and with the Raytheon’s you want the black plates.
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Thank you, just ordered them!
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Had a chance to listen to these tubes today, but unfortunately they didn’t gel with my system.
Not a bad tube, just a little too mellow for my tastes, in my system.
If anyone is interested, I’ll sell them for I paid for them. $37, and I’ll pay for shipping.
Gary
If you need to go back in the other directions you can try the 1952 Sylvania’s as they are more to the “neutral” side of things which may balance out the tubes you have in the amps.
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Thanks, I may give them a try, but at this point my system sounds so satisfying to me in every way, I think I’ll stop tinkering with it for a while. Trying to hunt down some more NOS Amperex 6922’s for the amp. Never want to live without out them, now that I know how they make the BHK 250 sing.
Well, Brent Jessee has supplied my favorite tube for the BHK pre so far. These NOS Telefunken 12AU7 smooth plates, medical grade are really something in terms of SQ ($400/pair so not cheap). Not too soft, not too hard (etched) just right for my system.
Very well matched triodes although I still get a minor click when changing volume. Not a big deal but oddly the much cheaper Baldwin 12AU7s were dead quiet and sounded great too considering they were $40 a pair!
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I decided to replace the tubes (12 AU7) in my BHK pre a few days ago. My old ones (PSVane) had over 9000 hours and still sounded ok, a little on the blah side, but no noise. I replaced them with Gold Lion 12AU7 from Parts Connexion and they sounded much better … for a day. Then I started hearing burbling noises in the right channel. It seemed to come and go so I left them in. Then I started getting loud pops when changing the volume, not good. So I put in some Amperex orange globe I had. No idea of the provenance, but no boxes so probably pulls from a long gone piece of equipment. They sounded ok, a little blah again, so maybe had a lot of hours on them already. No noise, though only for a couple of days when some low level scratchy sounds started up. Worst part, it was in the right channel again, I feared a circuit problem. So I put the Gold Lions back in to verify the noise moved with the tube, after a couple of swaps I confirmed it’s the tube. Phew! Disappointing a new tube was bad but such is life. So I put in another new pair of Gold Lion this time from the Tube Store. After an hour they sound great! Fingers crossed it stays that way. So now some questions …
First off I don’t know which tube is the left channel or right channel. Anyone know which channel V1 (the circuit designation) is? I want to keep the noisy tube from being reused.
The Tube Store tubes seemed better matched than the Parts Connexion tubes, but not sure how precise matching is. So, how important is tube matching for this pre? Do all the measurements have to match or just a specific one (or two)? Here’s what I have:
Parts Connexion
Tube 1 - Mu 16.1/15.3 Gm 1475/1431 Vn -65.5/-67.4
Tube 2 - Mu 16.1/16.5 Gm 1326/1470 Vn -65.8/-66.8
Tube Store
Tube 1 - Mu 15.7/16.1 Gm 1350/1345 Vn not supplied
Tube 2 - Mu 15.7/16.0 Gm 1370/1415 Vn not supplied
The small circuit board vertically mounted behind each tube is reported as removable on some units but not others (soldered in place). I think it was Baldy who said they come out easy. Mine would not budge, but the pins went into a black plastic piece which looks like a socket. Can’t see the underside and I don’t want to force anything so does anyone recall if the soldered version is identifiable from the top?
Thanks for any help!
P.S. I should call PS Audio, but given they are probably closed tomorrow and maybe, shall we say, not to well focused today shortly before a long holiday I’ll rely on the forum for now.
I was told that some of the riser boards were lift out and some were soldered in. I have forgotten when the change was made and whether solder in was early or late production. If it doesn’t come out easy it is probably soldered in.
I believe that the left channel is on the left side of the chassis when viewed from the front. It should match the left output connection on the back panel.
You might try cleaning the pins on your tubes or straightening them and see if they behave a little better. I tried several 6V tubes but ended up going back to the stock 12V PSA supplied tubes. I may get back to tube swapping but I will stick with 12V on the preamp.
Hope this helps!
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Thanks! When it wouldn’t pull out, I assumed it was soldered, but the black plastic piece looked like a set of plugs. I’m not going to worry about it … I’m sticking with 12v tubes too, read too many bad experiences. I’m not really worried about getting the last little bit from a preamp so no real tube rolling either. Still would like to hear from someone on the tube matching.
I don’t have any knowledge about the measurements on individual tubes so I can’t help there. I told someone here that what I really want is a solid state device that can be adjusted to represent various tube traits without the problems that tubes can bring to the party.
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I’ve read that Bob Carver was capable of designing circuits to match sound wise whatever topology someone suggested. Not really the same thing, but it could be done, though maybe a lot more complicated than you think. One other thing popped into my just now, I recall Paul saying when designing the BHK 250 he was strongly against using a tube. I’m not sure if it was Paul or Bascom who came up with a solid-state device that could be swapped with a tube in the tube socket. Tube won!
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BHK pre amp mated with 12au7 , if use 12at7 instead , does the overall gain will be increased?