Random distortion tube mic related or?

When you say distortion, are you referring to that weird artifact that happens right before the word “days,” or are you talking about the tone in general being kind of fuzzy/gritty/overdriven?

Hard to draw any conclusions from such a short clip, but I dealt with a similar issue a few years ago and it was a really frustrating experience getting it sorted out.

I would recommend process of elimination. To start, take as many variables out of the equation as possible. Go straight from the CU-29 to your Apollo, no Unison pres or FX enabled. Just the clean, stock mic pre with the gain set really low. If you still hear it, try the pad on your Apollo, or use an inline XLR pad.

Barring that, try a different mic, preferably something new so you know the condition isn’t a confounding variable. If the issue goes away, you know it’s something with the Tele/Apollo. Could be a tube going out, dirty capsule, or a bad component or connection somewhere in the mic circuit or PSU. It’s also worth a shot to swap tubes and try different mic cables (including the 7-pin tube mic cable) — inexpensive and doesn’t involve sending the mic off for repair.

On the other hand, if you go straight to the Apollo mic pre and DON’T hear it, you’ll have to insert your other gear in the chain piece by piece. Start with the 710, since it happens with both of your analog chains. If you reintroduce the 710 and the issue comes back, you know that’s the culprit. Try all four of the 710 preamps at low gain. Put one of your BAEs in the chain and try all four line inputs. If it happens with all inputs, it might be something wacky with the digital connection or clocking between your 710 and Apollo. Make sure you’re setting the 710 as the master clock in Console. Not sure which Apollo you’re using, but try different cables for the digital connection (whether that’s ADAT or AES/EBU). Try different BNC cables if applicable. And of course, try different cables for the line level connections, too.

If reintroducing the 710 doesn’t bring it back, then it’s probably something with your BAEs or compressors. Since it happens with both chains, I doubt it would be a failing component, but since both BAEs are fed off the same PSU, that might be the problem. It could also be a grounding issue or interference. Hard to say. I’m not too well-versed on troubleshooting that kind of stuff. In that scenario, maybe try running the BAEs off a UPS or maybe see if you can get a separate BAE PSU to test.

Now, going back to the first step, if you try a different mic direct into your Apollo, you might actually get the same issue. This happened to me. In my case, the solution ended up being astonishingly simple — it turns out the A/D on the Apollo MKI just sounds grungy and distorted to me, and the other converter I had at the time (Lynx Aurora MKI) wasn’t much better. Getting a Lavry completely solved it for me. No guarantees that this will be the case for you, but if none of the above fixes your problem, it might be worth testing a separate A/D to see if it goes away.

Super long post, but I know how painful it was to deal with this, and I would never want anyone else to go through that.

Here’s an older thread from the UAD forums on the same issue:

uadforum.com/community/index.php?threads/apollo-twin-mkii-distortion-issue-with-example.40451

Hilariously, you can see some of my old posts back when I bought my Aurora in 2020 and THOUGHT I fixed the problem… only to come back a few months later basically admitting it was wishful thinking.

The OP in that thread eventually upgraded to a rackmount Apollo X and still had the same problem. If you search around, there are numerous other threads about vocal distortion issues with the Twin. I’m not saying this is definitely the culprit in your situation, but it’s worth considering.

UPDATE! Ok, so looks kinda good in the sense that I'd say that the expensive gear is ruled out . I plugged straight into apollo and was eventually able to reproduce the fuzzy distortion with both the copperhead and eventually with the AT4047, though the AT was maybe slightly more subtle but non the less, audible.

The link to the UADforum was actually great as it kind of felt very similar though I didn't find any sound samples to compare with, the descriptions was darn close to what I feel. I will try reset of the unit and see if that makes any difference.

Then there is ofcourse on thing that's been also circulating in my mind since it seems easies to reproduce with the word "down" in the vocal line ive noticed I have the easiest to reproduce the issue. Is it in my voice??? but it doesnt sound like anything ive heard before in that context. I dont have a vocal session coming up shortly that i could try to find out if its only me... and I am kind of trying to trace this down before the next session

.... and sorry to say, it didn't solve it. seems less though than before, but still getting the distortion. I am positive though that it has to be in the apollo as all other options are pretty much ruled out. I've opened a ticket with UA so lets see what response there will be.

Yeah maybe it takes a few clips to realize the distortion, and when you hear its really obvious. Its during the word “days”. Might take a set of headphones to properly hear it. I have now taken the unit back for warranty service (well the warranty is exceeded by 4 days, so lets se what they respond).

I think maybe you have a little James Hetfield in your vocal style. If you don’t, then jitter can cause a same Hetfield-ing.. or what I refer to as jitter anyway-not sure it’s the technical term. Sometimes digital stuff can sort of lose time for a few samples and jump around trying to speed up/slow down to lock with the daw again. I’ve had that a lot with older computers and budget 1394 or USB ports. Usually though it’s accompanied with a squeaky glitch.. sometimes I have had issues where clocking sort of ‘varispeeds around’ for a second or two, causing me to go back and wonder if I heard it or not. Reaper will do this sometimes -since I have it set to try to play even with too many plugins, where other DAWs just won’t let you play at all. Is this maybe what you hear?

I definitely hear a little blip right at the beginning of "days" in that clip. I'm probably overly sensitive to this kind of thing because I almost lost my mind trying to troubleshoot it for 4 - 5 years.

Obviously, this clip alone isn't enough to make any definitive statements — it could very well be a mouth noise or the singer shuffling around or something. But if it's happening consistently and it's repeatable as OP states, that suggests it might be something else.

I don't want to immediately jump the gun and point fingers like, "It's the Apollo!!!!!!!!!" But I used to get subtle, artifact-y junk like this ALL the time when I was on my Aurora MKI + Apollo Twin setup. It's a shame, because this definitely doesn't happen to every Apollo user. And to be fair, there's still the chance it's a bad mic cable or interference or something.

OP, if you are able to, I would see if you can try out a high end converter, just for peace of mind. I would recommend something like a Prism Lyra, Apogee Symphony, Lynx Hilo, or maybe an Antelope Orion. If that doesn't fix it, you can return it and continue troubleshooting.

I agree. I have a bunch of clips where Ive been able to replicate the sound, and though i for some time was convinced it was my voice, i came to the conclusion in the end it wasnt, since i got more samples to listen to. Sadly I do not have easy access to any of those converters. But my chain goes as following: mic, bae1073, either la2a or 1176, ua 4-710 which I also use as the converter and then to the apollo thru adat. The noise was present in all setup variations including mics straight into apollo as a stand alone unit. So I cannot figure where else the issue could be than inbthe apollo. At that stage all possible cable issues etc. are also bypassed. 

If it’s not the vocal pitch warble, I can sort of hear a subtle grind or scratch. Sounds like something like a beard rubbing on a mic grill or clothing touching the mic stand? It’s not noticeable at all but if that’s happening all the time in everything I could see it being frustrating. ADAT can be jittery and sometimes can produce those weird warbles.. just keep that in mind - sometimes it’s not always performance

Yeah, the tube and capsule were one of the first suspects on the list, but they got ruled out in the end.