Let's talk pre amp tubes ... old and new, long plate and short ....

Dr. Tweedbucket

Deluxe model available !!!11
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48,126
.... Chinese and Russian vs USA or Europe.

First of all, take a gander at this:

http://www.300guitars.com/articles/preamp-tube-gain-factors-and-substitution-chart/

So, really any of these should work ok in a guitar amp, right? Someone said the 12AV7 wasn't for musical applications and could be microphonic, does that sound right? I've used them in guitar amps before and they seemed fine to me. 12AU7s are good for taming overly aggressive amps, or for adding a bit of headroom.

How about long plate vs short plate? I have a Reeves amp that has only 1 preamp tube, so it's a good test bed for listening to pre amp tube qualities. I spent a few hours one time swapping out tubes and I found the long plate tubes sounded better in general to my ears than the short plate tubes. I don't know why, but the mids and bass was fuller and more pleasing. Some of the short plate tubes were more ice picky, but not all. Any opinions here?

How about black plate vs gray plate tubes? What's the difference in material and tone in your opinions? :confused:


Finally, how do the vintage octal pre amp tubes compare to the more modern nine pin mini tubes as far as tone and over all quality of sound is concerned?

Thanks.
 

straightblues

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9,653
I am not sure if you were asking a question or just sharing your observations.

I have a large preamp tube collection (around 150 tubes). I pick them up wherever I see them, places like garage sales, swap meets, ebay, and amp repair shops. They are almost all used but still test good. I never pay a lot for them.

Whenever I buy a new amp, I spend a couple hours swapping tubes in and out of it until I find the ones I like most for each position. I don't look at brand names until I am done. Sometimes, new cheaper tubes sound the best, but most the time vintage tubes come out on top. Whatever tube wins, I then go buy brand new versions of that tube and use them in that amp.

I am always surprised at what sounds good in a particular amp. It always seems to be a little bit different. Some amps need more gain to sound good, while others need less. Some need to be pushed into a more of an aggressive British voicing to sound right, while some want more traditional American Fender type tones. If you know about preamp tubes, you can guess which tubes will allow you to gently shape the tone of the amp.

You can also adjust the tone of the amp via mods and speaker changes. But I like to start with the tubes first.
 

Satyrnine

Member
Messages
6
I can't speak the the 12AV7, but I definitely prefer long plate to short plates as well. The downside is some long plate designs are more prone to microphonics, especially in area's where they are abused such as combo amps or bass amps. I use long plates whenever possible. I agree with your observations about long vs short plates. "Less harsh" and "more detailed" instantly comes to mind. That said, there are definitely short plate designs that blow my mind. Tungsram, Telefunken, RFT (one of my favs), JJ, and many others all make really really great short plate tubes in my opinion.

From what I've experienced and heard from fellow tube addicts, black plates are generally better sounding than grey plates. Black plates are typically earlier tubes. Whether that's strictly because of the plate material, or because of other characteristics inherent in early manufactured tubes, I can't be sure. I can't really find enough consistency between black/grey types to tell you "black sounds like this", but I generally like black plate designs.
 

Heady Jam Fan

Member
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9,009
I always avoided 12AV7's because I've heard the same thing - they can be microphonic. I like 12AY7's in my DR thought. That chart surprises me. A Fender calls for a 12AT7 reverb driver and the most popular sub is a 12AU7 (RCA Long Plate). Yet that chart does not list it as an acceptable sub.
 

Dr. Tweedbucket

Deluxe model available !!!11
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48,126
I am not sure if you were asking a question or just sharing your observations.
A little of both ... I'm just asking for opinions to see if they match up with what I've found so far. Sometimes you can learn things from other's opinions and experiences. :dunno This too is to benefit another person I know who is interested in preamp tubes for a small watt amp he has.
 

Trout

Member
Messages
7,550
Have 30-50 12AV7's in a box in the basement,, useless investment at best.
I found 1 tube that worked in V1 for a short time,, the rest squeal like crazy even at idle.
 






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