Koch Little Gristle - Killer amp for intensive daily use in (and out) of jazz

[Jx30510]

Thanks for the reply.
What gets me a bit questionned is the tube socket ?
I'm not sure an EL34 socket is the same as the 6V6, and moreover the 6L6?
Maybe an adaptator is needed ?
Koch's answer gets me curious here

[Oscar67]

Many common power tubes use the same socket, except the EL84. I also asked Koch about tube swapping and the amp can handle it. I’ve already tried a 6V6 in mine but prefer the stock EL34. I did swap the 12AX7 for a vintage military spec NOS 12AT7 and am very happy with that.

Perhaps it’s worth repeating for those who didn’t work their way through this whole thread that this amp wasn’t designed specifically for jazz. It’s certainly not a Polytone, a Jazz Chorus or a Bud. It’s also not a Twin or a Deluxe. It’s an affordable, reliable, versatile tube combo that can very work very well in some jazz contexts (as well as in many other outside of jazz). If you like the classic Kenny Burrell sound that’s _just_ shy of having some hair on it, or some of Jim Hall’s early work with Paul Desmond, or Barney Kessel’s tone on the first Julie London album, or some of the stuff Julian Lage does today, then this might be an amp worth checking out. Ditto for those who play in loud big bands or other dense soundscapes: this amp will have your back.

[Jx30510]

Thanks.
What did the 6V6 do to the sound?

[Srini]

Many common power tubes use the same socket, except the EL84. I also asked Koch about tube swapping and the amp can handle it. I’ve already tried a 6V6 in mine but prefer the stock EL34. I did swap the 12AX7 for a vintage military spec NOS 12AT7 and am very happy with that.

Perhaps it’s worth repeating for those who didn’t work their way through this whole thread that this amp wasn’t designed specifically for jazz. It’s certainly not a Polytone, a Jazz Chorus or a Bud. It’s also not a Twin or a Deluxe. It’s an affordable, reliable, versatile tube combo that can very work very well in some jazz contexts (as well as in many other outside of jazz). If you like the classic Kenny Burrell sound that’s _just_ shy of having some hair on it, or some of Jim Hall’s early work with Paul Desmond, or Barney Kessel’s tone on the first Julie London album, or some of the stuff Julian Lage does today, then this might be an amp worth checking out. Ditto for those who play in loud big bands or other dense soundscapes: this amp will have your back.

I concur. Your experience with the 12AT7 was pretty much the same as mine with the 4024 - it was just not crunchy enough for me. But what a sweet tone! As you suggest, it may be better to evaluate the amp on it's own terms rather than trying to emulate something else. It has a beautifully versatile voice of it's own, and I realized yesterday that it makes me sound more like myself than just about any other amp I've owned - with the possible exception of the Gries 5.

[ruger9]

Some amps can take a few different power tubes without adjustment, because they are cathode-biased. My Swart AST can do this. I haven't tried it, as anything other than the stock 6V6s will be louder, and I don't need the amp any louder!

But this thread has me wanting to pull the Little Gristle back out and try a JAN 5751 in V1. And I will also try it into a broken-in speaker (a greenback type Scumback M75 and a Eminence Cannabis Rex)

[Oscar67]

Thanks. What did the 6V6 do to the sound?

I didn’t think it was an improvement. The EL34 sounded fuller, punchier, livelier. I intend to try a 6L6 and a KT88 one day but am in no hurry because the EL34 sounds killer.

[Srini]

Some amps can take a few different power tubes without adjustment, because they are cathode-biased. My Swart AST can do this. I haven't tried it, as anything other than the stock 6V6s will be louder, and I don't need the amp any louder!

But this thread has me wanting to pull the Little Gristle back out and try a JAN 5751 in V1. And I will also try it into a broken-in speaker (a greenback type Scumback M75 and a Eminence Cannabis Rex)

Good idea, but something tells me you're not going to like the 5751. I'll wait for your assessment.

[Srini]

I didn’t think it was an improvement. The EL34 sounded fuller, punchier, livelier. I intend to try a 6L6 and a KT88 one day but am in no hurry because the EL34 sounds killer.

I'll try the 6L6 today and let you know - I suspect that you and I are very much on the same page.

Srini

[ruger9]

Good idea, but something tells me you're not going to like the 5751. I'll wait for your assessment.

Well, "smoother" sounds good... sometimes a 5751 "takes the edge off" a 12AX7, which can be good for the high end part of the gain, making it less strident.

[Srini]

Well, "smoother" sounds good... sometimes a 5751 "takes the edge off" a 12AX7, which can be good for the high end part of the gain, making it less strident.

Very true, but you could lose a fair amount of gain, and you mentioned that that is what you're going for. I've found that using the guitar's tone control takes the edge off very effectively while keeping the gain.

By the way, upon reflection, do you think your feeling that the amp is stiff could stem from the fact that your Swart uses a tube rectifier?

Srini

[alltunes]

I didn’t think it was an improvement. The EL34 sounded fuller, punchier, livelier. I intend to try a 6L6 and a KT88 one day but am in no hurry because the EL34 sounds killer.

That is what I have found too in other amps. EL34s do have a mid range focus and perhaps a tighter bass and later break up than a 6L6. Regardless it is fun to be able to swap power tubes without a rebias.

[ruger9]

Very true, but you could lose a fair amount of gain, and you mentioned that that is what you're going for. I've found that using the guitar's tone control takes the edge off very effectively while keeping the gain.

By the way, upon reflection, do you think your feeling that the amp is stiff could stem from the fact that your Swart uses a tube rectifier?

Srini

That could be a part of it, altho it's not that simple.... for example, the Swart is stiffer than my Hot Cat, but the Hot Cat is solid-state rectified. I suspect it has "sag resistors" which are utilized to provide a little compression/sag when there is not a tube rectifier. My Fender Supersonic 22 on the other hand, seems to have little to no sag... it also is solid state rectified. It really depends on the entire circuit, not just part of it.

[Srini]

Alrighty then, ladies and gentlemen...I know you've all been waiting with bated breath.....

Anyhoo.....JAN Philips 6L6WGB - quite honestly it was reminiscent of the CV4024 with the EL34. Same beautiful, fat tone, but even with the master at 3 O'clock, it pretty much stayed clean (extra gristle ON, all other knobs at noon) in my usual guitar settings - 7ish on volume and 6/7 on neck tone, about 4 on bridge tone. Turning the guitar volume all the way the amp starts to grind, but noticeably less that the EL34. It's not quiiiiiite as bright, but then again, my old ears could be fooling me. Except for the lack of "dangerous" breakup, as you would say, I'm really hard-pressed to tell the difference.

RCA blackplate 6V6 - I would have to say, this is a grindier and thinner version of the 6L6. If brightness is a problem, you may not like the 6V6. That said, I have not tried it with the CV4024, so that may be a little fuller sounding and cleaner - I don't know.

This is how I would rank them:

12AX7+EL34: Crunchy combination, and I would have to say, my favorite. Cleans up very well with the guitar volume.
CV4024+EL34 and 12AX7+6L6: Very similar sounding, and my favorite if I were doing a jazz gig - this one is a tie. It does clean up well, but there's not much to clean up.
12AX7+6V6: Crunchiest and most "dangerous" sounding of all, and also the thinnest. It cleans up well, but the clean tone is thinner than either the EL34 or the 6L6 - and that may be a good thing for R&B rhythm guitar. I can see this combination being indispensable while recording, because I suspect both lead and rhythm will sit very well in the mix (depending on the genre, of course).

Bottom line: I'm going to stay with the 6L6/12AX7 combo for now. Overall, I like it almost as much as the EL34/12AX7 combo, but it's cleaner.

FWIW!

Srini

[Oscar67]

Thanks for trying those tubes and reporting back. I’m going to track down a nice 6L6.

[Oscar67]

Update. I’ve changed the stock Vintage 30 to a Celestion G12-M Hempback. Because the amp is front-loading the swap was quick and easy. No need to remove the tubes or anything. Unfortunately I nicked the tip of my left index finger when opening the box. It’s bleeding a lot so I couldn’t really play, but a quick try with the remaining fingers suggests slightly silkier highs and mids, though the difference is smaller than I had expected. To be continued.

While swapping the speaker I noticed that pretty much every screw on this amp was loose and in some cases had no grip at all. I tightened everything. The cabinet wood is matchstick wood. That’s disappointing. Still like the amp’s sound but if you have one of these then better check everything or you might be holding just the faux-leather handle while hauling the amp up a flight of stairs.

[Srini]

Update. I’ve changed the stock Vintage 30 to a Celestion G12-M Hempback. Because the amp is front-loading the swap was quick and easy. No need to remove the tubes or anything. Unfortunately I nicked the tip of my left index finger when opening the box. It’s bleeding a lot so I couldn’t really play, but a quick try with the remaining fingers suggests slightly silkier highs and mids, though the difference is smaller than I had expected. To be continued.

While swapping the speaker I noticed that pretty much every screw on this amp was loose and in some cases had no grip at all. I tightened everything. The cabinet wood is matchstick wood. That’s disappointing. Still like the amp’s sound but if you have one of these then better check everything or you might be holding just the faux-leather handle while hauling the amp up a flight of stairs.

Oh man, sorry to hear that! I hope your finger heals quickly.

It's shame about the build quality, although I personally don't plan to move it much, and use it as my studio amp. I have to say that I totally love the sound of the amp, and I'm still sticking with the JAN Philips 12AX7 and the JAN Philips 6L6WGB (I assume this is more like a 5881, right?). I'm very pleased with the tone, but may experiment with a KT77 some time. I assume, that's technically possible.

Srini

[ruger9]

The build quality on mine seems fine, no rattles or buzzes or anything...

[Oscar67]

It's shame about the build quality, although I personally don't plan to move it much, and use it as my studio amp. I have to say that I totally love the sound of the amp, and I'm still sticking with the JAN Philips 12AX7 and the JAN Philips 6L6WGB (I assume this is more like a 5881, right?). I'm very pleased with the tone, but may experiment with a KT77 some time. I assume, that's technically possible.

I still like it very much as well. Am still using the mil-spec vintage 12AT7 in the preamp and the stock EL34 in the power amp. It’s a fun amp.