Swapping tubes in an ART Pro Channel?

[paparoof]

I recently got an ART Pro Channel for my home studio, I've used it for bass and voice so far and I'm happy with it. From the reading I've done on it, it seems most people like to swap out the tubes for something a little better than stock. However I don't see much in the way of specifics after that. I was about to just order an assortment of affordable tubes and decide through trial and error, but thought I could probably rule out some dumb mistakes if I ask here first.

There are three tubes, one in each section of the unit; preamp, compressor, EQ. Can someone school me a little bit about what differences I should (or should not) expect by swapping out each of those three tubes?

Then of course I'd love to hear specific tube recommendations. I'm not really fond of the overdrive the stock preamp tube gives me, I'd love a tube that could give me that Geddy Lee/Chris Squire kinda growl.

 

[ahiddentableau]

I have a Pro Channel and I've messed around with the mods you're talking about, but my recommendation is to avoid tube swapping on that particular unit. Keep in mind that it's made and biased for 12AT7s, not 12AX7s (a much higher gain tube). So when you change them out, you can really mess with the response of the circuits because they just weren't designed to be used with that kind of part. In my own trial-and-error tests (in spite of my reservations, I tried these mods anyway), you can put a higher-mu tube like a 12AX7 in the preamp slot and rebias it hotter, and it does give a bit of a higher gain sound. But it's not much of a difference (barely noticeable, really) and it's pretty furry. Qualitatively no better than the stock sound. More importantly, and this is why I wrote this so you can avoid a big waste of time, there is no good that comes from messing with the other circuits. The compressor and EQ were designed to be used with 12AT7s, and the bias is set accordingly. If you start messing around without knowing what you're doing, you're probably just going to mess up the bias on your compressor and make the tube circuit less useable and noisey up an EQ that ain't so whisper quiet to begin with. Given that the opto comp on the PC is where it's at anyway, maybe you don't care, but IMO, it's a bad deal all the way when you start messing with those parts. Risks definitely outweigh the returns.

Best of luck with your unit!

 

[Ben Clarke]

I didn't think OP was asking about different types of tubes, but rather different examples of 12AT7. I may be wrong in that assumption.

12AT7 are not as common a tube as the X and U in circuits we see nowadays, and I for one haven't messed with them a whole lot. What I have found, though is that getting a Chinese generic out of the circuit and a working 80s or earlier tube in there is pretty much always an improvement.

 

[paparoof]

Hey thanks for correction.

If I can just play the noob card with one more post, let's pretend I never said 12AX7's and I said 12AT7's (the manual doesn't specify and I haven't opened up the unit, in fact some other website said 12AX7's, yet another claims 2 12AT7's and one 12AX7).

Are you saying the compressor and EQ section would not benefit from any tube change at all or only that they would not benefit from 12AX7's? There is NO tube upgrade that's worth it here? I did read elsewhere that the optical compressor was generally preferable anyway - at least that piece is consistent.

So if the preamp section is the only place left where a tone difference might be noticed, is there a 12AT7 that would make a positive difference? I shouldn't have given the impression that I'm just going for the Geddy thing, I'm really looking for different flavors whatever they may be. Words like "round" and "woolly" and "warm" are so subjective I really would like to do some experimentation here just so I can hear it for myself. I can always stick the stock tube(s) back in if I don't like what I'm hearing with others - right? Am I missing something important, like potential permanent damage if I stick the wrong tube in there - even if it's only for a short time to test it?

Maybe the ART Pro Channel isn't the place for me to learn about flavors of different preamp tubes. I was under the impression this was a "real" tube unit, not one of those "toob toyz" units where the manufacturers just jam one under the hood so they could put the word "tube" on the packaging.

What's the whole story here?

 

[paparoof]

I didn't think OP was asking about different types of tubes, but rather different examples of 12AT7. I may be wrong in that assumption.

Yeah - let's pretend that's what I meant. Full-disclosure: I *was* talking about 12AX7's, but after re-reading it, I don't see that I mentioned any specific tube types.

12AT7 are not as common a tube as the X and U in circuits we see nowadays, and I for one haven't messed with them a whole lot. What I have found, though is that getting a Chinese generic out of the circuit and a working 80s or earlier tube in there is pretty much always an improvement.

Can you be more specific?

 

[seamonkey]

Your best bet. Find a shop with a good supply of different tubes.
Call ahead and ask to try out a bunch of different tubes. Take your gear and spend a couple of hours.

Watch out for fakes
FAKE TUBES LIKE ECC803S and others
There's a big counterfeit market. Nobody is really watching.

 

[Ben Clarke]

You should email ART for the info on stock tubes. they will probably shy away from recommending tube experimentation as it's too subjective to really respond as you might hope.

What I would suggest is remove the stock tubes and replace with an older production tube of the same type. A bit of googling around can reveal sources with a good track record, but I'll stop short of recommending anyone in particular as it's been a while since I bought tubes regularly. My pantry is fairly well stocked.

Yeah - let's pretend that's what I meant. Full-disclosure: I *was* talking about 12AX7's, but after re-reading it, I don't see that I mentioned any specific tube types.



Can you be more specific?