Kniferide wrote: Wed Nov 24, 2021 12:14 pm

cakes wrote: Wed Nov 24, 2021 11:47 am What tubes did you upgrade with?

So for tubes I just dropped in some NOS GE and RCA 12AX7 I had hanging around. I didn even listen to the stock tubes because I know them to be cheap Chinese tubes and I had "better" tubes already sitting here. I also replaced the AT7's with Tung Sol because I had them here in a box. The more important modification is this. The Pro Channel II gets user reports of having hum and noise if cranked. A dude looked at the schematic and found that between the Pro Channel 1 and 2 they added 2 47ohm resistors that bypass the voltage regulator in the powersupply and it causes voltage ripple. Over my head. He says you clip those resistors and the noise goes away. I did it, and mine have been fine for months with no ill effects.

Now, here is the thing. The Pro Channel II can be found dirt cheap on Ebay because people hate this hum. Cutting a piece of electronics out of a piece of gear that an engineer decided to put in there is a risk, but seems to work. Use caution. I have seen these go for less than $200 because they are "Broken" and fixed with this process.

Here is the thread that explains it.
https://gearspace.com/board/so-much-gea ... oblem.html

I've been trying to find what the difference is between the Channel II and the Channel I, because the Channel I is much cheaper.

cakes wrote: Wed Nov 24, 2021 12:27 pm

Kniferide wrote: Wed Nov 24, 2021 12:14 pm

cakes wrote: Wed Nov 24, 2021 11:47 am What tubes did you upgrade with?

So for tubes I just dropped in some NOS GE and RCA 12AX7 I had hanging around. I didn even listen to the stock tubes because I know them to be cheap Chinese tubes and I had "better" tubes already sitting here. I also replaced the AT7's with Tung Sol because I had them here in a box. The more important modification is this. The Pro Channel II gets user reports of having hum and noise if cranked. A dude looked at the schematic and found that between the Pro Channel 1 and 2 they added 2 47ohm resistors that bypass the voltage regulator in the powersupply and it causes voltage ripple. Over my head. He says you clip those resistors and the noise goes away. I did it, and mine have been fine for months with no ill effects.

Now, here is the thing. The Pro Channel II can be found dirt cheap on Ebay because people hate this hum. Cutting a piece of electronics out of a piece of gear that an engineer decided to put in there is a risk, but seems to work. Use caution. I have seen these go for less than $200 because they are "Broken" and fixed with this process.

Here is the thread that explains it.
https://gearspace.com/board/so-much-gea ... oblem.html

I've been trying to find what the difference is between the Channel II and the Channel I, because the Channel I is much cheaper.

Pro Ch II has a HIgh Voltage mode that heats the mic pre tube with something like 180v, instead of the typical starved plate mode. It does indeed give you more head room. Other than that, the 2 removed the tube from the comp section, which is fine because it was only used for makeup gain, and whatever. I'll trade that for a hotter tube. Other than that, I think they are the same. There are mods to jump that tube voltage up to about 220V too, putting it closer to where it wants to be.

OH! 2 has a instrument input too. I use this more than anything else.

I got my two on ebay for $350 for the pair because of the Hum problem. They arrived basically not packed and both VU meters were broken (fine, they are useless) and a couple of smashed in knobs and a button, bent rack ear. They guy was cool about it and refunded half of the purchase amount so I got both for $175. The repairs were easy, and the Mod fixed the hum problem. VU meters look street tough now.

Just picked one up on Ebay for $280. That was about the cheapest I could find one. I have a few extra JJs in a box if I wanted to swap tubes. Thanks for the info on the buzzing. We'll see how it works, I'll be powering with a conditioner, maybe that will help? Anyway, this seems like a nice utility for my needs!

cakes wrote: Wed Nov 24, 2021 2:12 pm Just picked one up on Ebay for $280. That was about the cheapest I could find one. I have a few extra JJs in a box if I wanted to swap tubes. Thanks for the info on the buzzing. We'll see how it works, I'll be powering with a conditioner, maybe that will help? Anyway, this seems like a nice utility for my needs!

It actually works great as a DI. I'll let you decide if the Buzz in the power supply is a problem, some people don't seen to have an issue. It is an easy fix if you want to try the mod. You just clip one end of the big ceramic resistors and leave them in place, you can always dab a little solder on the place you clipped it if you want to return it to stock. That Gearspace thread has all the info. Cool thing about these is you can wire the comp or eq up to normalled jacks on the patch bay and just use those sections if you want.

Kniferide wrote: Wed Nov 24, 2021 2:21 pm

cakes wrote: Wed Nov 24, 2021 2:12 pm Just picked one up on Ebay for $280. That was about the cheapest I could find one. I have a few extra JJs in a box if I wanted to swap tubes. Thanks for the info on the buzzing. We'll see how it works, I'll be powering with a conditioner, maybe that will help? Anyway, this seems like a nice utility for my needs!

It actually works great as a DI. I'll let you decide if the Buzz in the power supply is a problem, some people don't seen to have an issue. It is an easy fix if you want to try the mod. You just clip one end of the big ceramic resistors and leave them in place, you can always dab a little solder on the place you clipped it if you want to return it to stock. That Gearspace thread has all the info. Cool thing about these is you can wire the comp or eq up to normalled jacks on the patch bay and just use those sections if you want.

Yeah, reading through that thread, it looks pretty simple. I was wondering why they left the resistors in place, so that's a really good point.

I got two open in/outs left on the patchbay, just waiting to be used!

I really love the Art Pro stuff, best bang for your buck! Off-topic, but I ended up finding some VSTs for Linux (Mac and PC) that has Pultec EQ, among other things. They provide free demos and the bundle pricing makes it even more appealing. Definitely interested in these for mixing, maybe even dipping my toe into mastering. https://www.overtonedsp.co.uk/

Update: Got the Channel II. It had some fuzziness in the EQ section, which went away by bypassing it. I opened it up and it had a Sovtek 12ax7, a decent upgrade. But the 12at7 was the China tube, and that was on the EQ circuit. I replaced it with a Groove Tube 12at7 and it made a load of difference, the fuzz just went completely away (it takes a minute or 2 for the tubes to warm up). Clipped out the resistors to remove the buzz. So far, it's not a bad piece of gear. You gotta really fiddle with the gain/master/preamp/compressor attenuators, but for the price I can't complain. It does what I was looking for and more!

Update II: Put the Channel II through more thorough work, and it's kind of a disappointment to be honest. Not sure if it's just this one, but the hum and buzz on the floor is really bad, even after modifications of cutting the resistors. There's a fuzziness to the EQ section, which I updated with a better 12at7. That fuzz was more pronounced with the original China tube, there slightly with the Groove Tube. More pronounced with a phantom powered large diaphragm than a dynamic microphone. Not pushing the section so hard helps of course, the but preamp section needs a lot of gain. The comp is probably the best thing about this thing, but is it worth just using as a comp? I not convinced. I wonder if there's something just wrong with this one. I have some other ART PRO pieces of gear, and while not premium quality gear, none of them are like this.

cakes wrote: Tue Nov 30, 2021 10:42 am I have some other ART PRO pieces of gear, and while not premium quality gear, none of them are like this.

That's a bummer man. Both of mine are completely fine. Clipping that the resistors made the noise not a problem. I think this is why they are so cheap on the used market, seems like the QC was all over the place for the II units. I just compared one of mine to a standard channel on my A&H console and if I crank all of the gain and volume controls, the noise is about twice that of a console channel with the gain cranked all the way, which is acceptable for something that has several more gainstages and some tubes in there.

Kniferide wrote: Mon Dec 06, 2021 1:33 pm

cakes wrote: Tue Nov 30, 2021 10:42 am I have some other ART PRO pieces of gear, and while not premium quality gear, none of them are like this.

That's a bummer man. Both of mine are completely fine. Clipping that the resistors made the noise not a problem. I think this is why they are so cheap on the used market, seems like the QC was all over the place for the II units. I just compared one of mine to a standard channel on my A&H console and if I crank all of the gain and volume controls, the noise is about twice that of a console channel with the gain cranked all the way, which is acceptable for something that has several more gainstages and some tubes in there.

I like the idea of a control strip, but the Channel II does seem to have some quality control issues. dbx makes a couple of strips, one is the 286s. Much cheaper, looks a little better overall. (Just mentioning if someone here in the future was on the same path.) Maybe because it's solid state, it doesn't have as many potential issues? The Channel II usable, but limited, depending on what you want to do. I would probably not use it for vocals, which is the real bummer because that was why I got it. Anyway, I think I'm gonna save up for an MPA II in the long-run, and then see if a strip is needed after that and decide what to do. I might just split out the compressor in the meantime, I could always use one more as outboard gear.

cakes wrote: Tue Dec 07, 2021 10:43 am

Kniferide wrote: Mon Dec 06, 2021 1:33 pm

cakes wrote: Tue Nov 30, 2021 10:42 am I have some other ART PRO pieces of gear, and while not premium quality gear, none of them are like this.

That's a bummer man. Both of mine are completely fine. Clipping that the resistors made the noise not a problem. I think this is why they are so cheap on the used market, seems like the QC was all over the place for the II units. I just compared one of mine to a standard channel on my A&H console and if I crank all of the gain and volume controls, the noise is about twice that of a console channel with the gain cranked all the way, which is acceptable for something that has several more gainstages and some tubes in there.

I like the idea of a control strip, but the Channel II does seem to have some quality control issues. dbx makes a couple of strips, one is the 286s. Much cheaper, looks a little better overall. (Just mentioning if someone here in the future was on the same path.) Maybe because it's solid state, it doesn't have as many potential issues? The Channel II usable, but limited, depending on what you want to do. I would probably not use it for vocals, which is the real bummer because that was why I got it. Anyway, I think I'm gonna save up for an MPA II in the long-run, and then see if a strip is needed after that and decide what to do. I might just split out the compressor in the meantime, I could always use one more as outboard gear.

Just checking, did you end up clipping those Resistors? I did some guitar tracking with mine last night and it was all good. I hate to have led you down a dead end path here.