7025a in the power stage?

[Capacitordeath]

So i've got 'em sitting here, already in sockets in an old organ amp, waiting to be brought back into service in a power stage. I'm planning on building a 5e5 or 5e7, and I'm looking for a pretty quick ramp-up into that wonderfully pushed, very warm sound that most tweeds I hear are famous for. I'm not looking for major crunch, but I'm not looking for pristine clean either. "thick and swampy" would be where i'm aiming.

I have read that 7025a tubes are very quiet, which says to me that they don't impart a whole lot of color to the mix.

Now...here's the thing. I have em right here, so if they will, say...get me close, I'll probably be happy with them and use em anyway.

has anyone used 7025a tubes in any sort of comparison with other tubes, like 6l6?

Thanks

[Bruce / Mission Amps]

A 7025 is a medium high gain preamp tube. It is equivalent to a 12AX7
Many tweed Fender amps use a combination of lower gain 12AY7s and the 12AX7s.
Not sure if you wanted to compare those 7025/12AX7s to the 6L6s or you actually have 7027-a power tubes....

[tubeswell]

Originally Posted by Capacitordeath

"thick and swampy" would be where i'm aiming.

Then tweed is probably for you. Maybe start with a cathode-biased amp like a 5E3, 5E5, or if you want trem with your cajun music, a 5E9A (or a 5G9, which even tho it is fixed bias, has a totally hypnotic trem).

A lot of the 'thickness' comes from the way the output stage is biased. If you keep the plate voltages lower and up the tube current, you get a more syrupy texture, and if you have the OT load resistance at about 5k5 - 6k6 for 2 x 6V6s in PP, or 3k2 - 4k for 2 x 6L6s in PP, you will get nice thick tones from the extra harmonic distortion - at the expense of a wee bit of power.

Originally Posted by Capacitordeath

I have read that 7025a tubes are very quiet

They were designed to be low-hum so they are ideal pre-amp tubes.

[Capacitordeath]

ack, sorry. I've been looking at different bandmaster specs, and some of them use a long line of 7025 preamp tubes, which are apparently very similar to a 12at7 or 12ax7. I meant that I had 7027-a power tubes, which are supposedly kind of like quiet 6l6s.

Sorry about the confusion. I'm new to processing this nomenclature.

[erndawg]

I never liked 7027s in a guitar amp. They just sound sterile to me. Ampeg had them in a number of amps that were not well-received.

Besides, when you eventually do have to replace those tubes, you won't be able to replace them with a 6L6/EL34/6550. You'll have to rewire the socket to do so.

[Capacitordeath]

they seem to fetch a hefty price. I'm thinking of either selling them, or trading someone for a chunk of what I need for the build, like either 6l6 + 12ax7 x 2 + tube socket, or the caps I need....something. Maybe whoever wants the 7027a tubes will want the 7199 I have as well.

[Enzo]

Or you can just buy current production 7027s to plug in there.

You can plug a 6L6 into a 7027 socket and it will work. What you can;t do as a rule is plug a 7027 into a 6L6 socket.

I happen to like the Ampeg amps.

[Capacitordeath]

It looks like Ampeg used the 7027a in it's bass tube amps, but it's got 6v6s in the guitar amps, which gives me a little more credence to the 7027a being more quiet and linear (linear is the term for uncolored, correct?), since a neutral bass tone is much more useful.
I think I'll take a whack at these tubes, but I'm probably going to switch them out for 6l6 tubes in the future.

[JoeM]

Originally Posted by Capacitordeath

It looks like Ampeg used the 7027a in it's bass tube amps, but it's got 6v6s in the guitar amps, which gives me a little more credence to the 7027a being more quiet and linear (linear is the term for uncolored, correct?), since a neutral bass tone is much more useful.
I think I'll take a whack at these tubes, but I'm probably going to switch them out for 6l6 tubes in the future.

Ampeg used the 7027 in guitar amps too. The VT40 and VT22 for example, and several others.

[Capacitordeath]

As long as I can go from 7027a to 6l6, I'll be happy. Heck, maybe if I get around to starting this project sometime this century, I'll even be able to show some tonal differences in the tubes.