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Guys, been auditioning a preamp with those tubes in the gain stage. In its stock tube form the bass is not articulate and highs are kind of suppressed.
Is there any 12au7 variants that can address the problem without breaking the bank? Should I consider the current production? I need a pair. If I don't keep the pre then I'm most likely stuck with the tubes.
Follow Ups:
If it does not sound good, why in the heck would you contemplate spending more money on it?
cheers,
Douglas
Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.
If you're auditioning this preamp and asking these questions, send it back now. From your profile it looks like you have some nice stuff. Don't get stuck with something that is going to be a journey into frustration.
I don't care what the experts say about the 12AU7 - it's not a good tube.
You seem to be going back to basics - shall I keep this preamp or.......?
So what is the preamp actually doing in your system?
- Does it provide phono equalisation?
- Does it step down the impedance for a long cable, or step it down for a solid state amp?
- Is it a kind of tone colour, making the sound nicer?
Given that you're putting this preamp and the tubes in it like the 12AU7 (a pretty mediocre tube) in the signal path, what's it doing that's better than no preamp? Have you tried a passive preamp or a transformer volume control?
The assumption that any system needs both an amp and a preamp has been challenged a lot recently, since modern digital inputs just need a DAC to interface with an analogue amplifier.
Would money be better spent on a better DAC?
Every time I use my volume control/switch box and think, "oh, what air, what purity", soon after I always go back to the Line Stage for that certain missing something.
Before you ask, the SUT and phono stage have enough output to leap tall buildings in a single bound. Quietly.
Eventually you make enough mistakes that you learn something and it looks like talent.
I echo this thought. I am connected my various sources through an RCA rotary switch and passive (Alps) volume control. For example, my primary digital source is a Schitt Lyr 3 with their multi-bit DAC, connected (via switch and volume control) to a McIntosh 240 tube amplifier. The results are great. My turntable, reel to reel, FM tuner, and other digital sources are handled in a similar manner. Yes, it's a bit of a kluge, but it works really well. Each of these devices have their own output stage, so no additional preamp seems necessary.
I dumped my preamp about two years ago and never looked back. What I do use is a Pass B1 buffer kit ($40) with a simple volume pot. It does NOT add an extra gain stages (and extra distortion) that is only going to be attenuated off.
the main reason a preamp was used for in the old days was to add gain to low level sources. Today, most sources put out somewhere near 2v.
Brimar 13D5 long plate is best I heard. Some Brimar are labeled Pinnacle on ebay.
Can you get a 12BH7 in there. I've never liked the sound of the 12AU7's. And I've tried a LOT of them!!!!!!!!!!!
Otherwise TungSol makes a really nice one which I preferred over the EH.
Made in the 60's, but they're still plentiful and not too costly.
Sure, people can argue forever re other superior tube types, but the fact is there are tons of tubed gear out there utilizing 12AU7 that sound superb.
I never said anything against the 12au7, I don't even care if it's 12au7 or 6sn7 -based, I care about the result, which is to enjoy the music.
The stocks are EH.
The 6CG7 is a much better choice from the standpoint of linearity, but filament wiring would be different. The 12AY7 is also much better and doesn't require wiring changes, but the amplification factor is 40. Pick your poison.
--------------------------
Buy Chinese. Bury freedom.
It sounds like there is a problem with how the preamp is designed.
Yeah, Chip, that was my thought too, I even canceled the order for a pair I ordered today. I realize if I don't like it in its plain form, then its no good for my setup. It's a brand new piece, so far it's breaking in, I'll see what happens. Appreciate the input.
Perhaps it is the 12AU7 that you don't like. When Morgan Jones tested medium Mu tubes, he found that the 12AU7 had 4.5 times the 2H distortion and 28 times the 3H distortion compared to a 6SN7. In fact, it was the very worst of all the medium Mu triodes he tested. As I recall, Eric Barbour found the same results in triode test in 'Vacuum Tube Valley'.
For full results see 'Valve Amplifiers' Fourth Edition by Morgan Jones.
I don't know to be honest. I had an integrated Unison Unico Se with those tubes, and it sounded great. Still regret selling it, it was using a pair of 12au7s and that was my only experience with them.
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