tubes. of the low gain variety

MoreSpaceEcho · Post by **MoreSpaceEcho** » Wed Jul 29, 2009 9:13 am

so i have this mesa boogie studio preamp thingy. i got it so i could record late night guitar ideas directly into the computer in a non-horrible sounding fashion. and it sounds surprisingly ok, the clean sound is nice. but! if i have the gain set where it sounds nice and round and 'tubey", if i lay into the guitar even the slightest bit, the tubes distort in a harsh, unpleasant way. it has a host of 12ax7s in there now. what can i swap them out for that will give me way less gain? 12at7? ay7? ak47?

"soft and spongey" would be what i'm looking for. i don't need any kind of wailing lead or crunchy riffin' sound, i have real amps for that.

anybody?

Rolsen · Post by **Rolsen** » Wed Jul 29, 2009 10:02 am

I believe the ay7 variety is lower gain that the ax7 - ac30 guys will do that swap to gain more clean headroom before breakup on newer voxes. The nice thing about ay7 is that they are in less demand, thus you can score a vintage Mullard that sounds sweet as hell for cheap compared to it's ax7 counterpart. I dont' know if it sounds squishy, though.

RodC · Post by **RodC** » Wed Jul 29, 2009 10:30 am

Here is a good chart to start you off:
http://thetubestore.com/gainfactor.html

Dont rule out some of the "unbalanced triodes" either. I like a 12dw7 if the pre is wired to use the low gain triode first.

MoreSpaceEcho · Post by **MoreSpaceEcho** » Wed Jul 29, 2009 10:58 am

thanks guys. that chart was most helpful. and i'm pretty sure i have au7's in my drawmer eq, which i've been thinking about swapping out for some nicer mullards. so i could take the old au7s and put those in the boogie.

is it any big deal to mix and match? like if i put in all au7s and it doesn't have enough gain, could i swap one out for an ax7?

RodC · Post by **RodC** » Wed Jul 29, 2009 11:18 am

MoreSpaceEcho wrote:thanks guys. that chart was most helpful. and i'm pretty sure i have au7's in my drawmer eq, which i've been thinking about swapping out for some nicer mullards. so i could take the old au7s and put those in the boogie.

is it any big deal to mix and match? like if i put in all au7s and it doesn't have enough gain, could i swap one out for an ax7?

You can mix and match, I normaly like to put lower gain tubes up front for less noise. ... but sometimes it can sound better with more gain up front, depends on how the pre is staged now.

Z-Plane · Post by **Z-Plane** » Wed Jul 29, 2009 11:31 am

Similar theme with different kit. I was having the exactly the same problem with a Vox Tonelab, I only used it for quick and quiet guitar tracking, and was reasonably happy with the sound. Then that harsh breakup started to drive me mad, and when I swapped the stock 12AX7 for an 12AU7 it improved no end. Almost every patch sounded better, with the high gain patches losing no gain, but becoming more nicely defined. A couple of caveats - the Vox ain't a Mesa but it does let you calibrate the valve circuit, and its a very odd hybrid circuit anyway, certainly a long way from traditional signal path and suggested plate voltages. Many guitar players are horrified by the words "low gain", but perhaps you might discover the same thing, that the sacred 12AX7 can wreck your tone in some preamps!

Recycled_Brains · Post by **Recycled_Brains** » Wed Jul 29, 2009 1:38 pm

If I were to swap out a 12AX7, for say, a 12AT7 in a small combo amp to get more clean volume, would I want to swap the V1 tube, or one of the others?

If so which?

RodC · Post by **RodC** » Wed Jul 29, 2009 2:29 pm

Recycled_Brains wrote:If I were to swap out a 12AX7, for say, a 12AT7 in a small combo amp to get more clean volume, would I want to swap the V1 tube, or one of the others?

If so which?

Depends on the amp...

Start by changing the very first one... Then try the very last one.

I have seen some amps that benifit from a lower gain in the phase inverter stage (if its push pull) or the final drive tube.

BOWIE · Post by **BOWIE** » Thu Jul 30, 2009 12:00 am

Yes, start with the first gain stage. Though a 12AT7 will give you alot more headroom, a vintage 6072 (high-grade 12AY7) would probably be a better choice as they usually have fuller-tone, lower noise and lower microphonics. 12AU7s will probaly be too noisy as they only have 1/5th the gain of what the circuit is intended for. however, it doesn't hurt to try and see what you like.
Also, cheap tubes are always going to be spongy and grainy. I've owned that Mesa preamp and it's pretty sensitive to the tubes you use.
And, by all means, mix and match.

Recycled_Brains · Post by **Recycled_Brains** » Thu Jul 30, 2009 6:31 am

RodC wrote:
Recycled_Brains wrote:If I were to swap out a 12AX7, for say, a 12AT7 in a small combo amp to get more clean volume, would I want to swap the V1 tube, or one of the others?

If so which?
Depends on the amp...

Start by changing the very first one... Then try the very last one.

I have seen some amps that benifit from a lower gain in the phase inverter stage (if its push pull) or the final drive tube.

Thanks.

I should have said that it's a Fender Princeton Reverb reissue.

It sounds great, but you can't turn it up past 5 and lay into it with out it breaking up a lot. The overdrive sounds amazing, but I'd like to be able to get a little more volume out of it before it starts to blow up at practice and for gigging.

KennyLusk · Post by **KennyLusk** » Thu Jul 30, 2009 9:01 am

BTW, 12AT7's will give your mids a nice "glow". They seem to bump the mids a bit and warm them up in almost an "aggressive" (but pleasant) way. NOS Philips 12AT7's are really hard to beat IMO but 12AT7's in general have similar behavior. Somebody mentioned mullard's earlier and yeah, mullard's have a really cool "wooly" tone to them that's unique.

BTW, FWIW, NOS GE's, Sylvania's, and RCA's are generally great brands as well. When you find yourself stopping at yard sales on saturday's just to look for old tube radio's, record player's and RTR's on the cheap so you can pull the tubes for your amp and mic pre's...you know you've got a problem. LOL, it happens.

RodC · Post by **RodC** » Thu Jul 30, 2009 9:17 am

KennyLusk wrote: When you find yourself stopping at yard sales on saturday's just to look for old tube radio's, record player's and RTR's on the cheap so you can pull the tubes for your amp and mic pre's...you know you've got a problem. LOL, it happens.

When you find an old tube that looks intersting in one of those old radios and you design an amp around it, call me, Im startin a 12 step program...

I got too many projects!

KennyLusk · Post by **KennyLusk** » Thu Jul 30, 2009 12:06 pm

RodC wrote:
KennyLusk wrote: When you find yourself stopping at yard sales on saturday's just to look for old tube radio's, record player's and RTR's on the cheap so you can pull the tubes for your amp and mic pre's...you know you've got a problem. LOL, it happens.
When you find an old tube that looks intersting in one of those old radios and you design an amp around it, call me, Im startin a 12 step program...

I got too many projects!

Rod, aren't you the kind soul that rescues the pre's from old Roberts RTR's?

RodC · Post by **RodC** » Thu Jul 30, 2009 3:09 pm

KennyLusk wrote: Rod, aren't you the kind soul that rescues the pre's from old Roberts RTR's?

Yup, and I have helped many others do the same....

We should start some kind of gov funded non profit type thing to revive this type of thing.

KennyLusk · Post by **KennyLusk** » Thu Jul 30, 2009 3:44 pm

RodC wrote:
KennyLusk wrote: Rod, aren't you the kind soul that rescues the pre's from old Roberts RTR's?
Yup, and I have helped many others do the same....

We should start some kind of gov funded non profit type thing to revive this type of thing.

yeah, get us some "stimulus" money, LOL.

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tubes. of the low gain variety

tubes. of the low gain variety

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