Weird harmonic added by amp...?

[Dusty Chalk]

So the DG Custom 50 came in, and because I live in an apartment, I'm living on the bottom half of the travel of most -- if not all -- of the knobs. (I'm tempted to obtain a vocal booth just to run some things at full tilt, but that's outside the scope of this thread, and not happening any time soon.)

Anyway -- the amp is adding a weird harmonic. Anything I should check before I contact the PTC?

Yes, I'll open it up and reseat the tubes, just in case, but it needs to cool off. I thought I'd ask while I was waiting.

 

[Dusty Chalk]

And by 'harmonic', I mean, 'interval', sounds vaguely ... ringmodulator ish?

Anyway, fixed it. One of the power tubes was visibly out of its socket -- not completely, but almost a centimeter. Pushed it back in (carefully, of course, just like a lightbulb, and without touching the glass directly), and the bizarro distortion/ringmodulator/invented harmonic effect is gone.

(bows)​

 

[RVA]

Isn't it great when the solution is simple? Rare, but great!

 

[Dusty Chalk]

It really is, both rare and great.

 

[Boogie]

...and there ya have it. Fixed! So, how do you like it?

 

[Dusty Chalk]

Tone report incoming, give me some time with it. Also, I'm dealing with sinus issues, so my hearing is off. More so than usual.

 

[jfb]

Congrats on a monster of an amp. Keep us posted. Your neighbors are going to love you I can feel it.

 

[László]

I want to read that tone report!

Incidentally, I know this isn't of much help, because Doug Sewell has said that the amp is meant to sound best with the Master dimed and you can only do so much in an apartment...but...

I have found the RealTraps gobo traps to be helpful in controlling the volume when set up around the amp.

No, they're not like having a Silent Sister cab, or the like, but they do help more than some of the other solutions on the market. You also probably also know about the Auralex Gramma products, that help to isolate the cab from structure-borne vibrations.

In addition, I also use an Isoacoustics stand to raise the cab up more away from the floor where the room modes live, and give things a little more clarity.

 

[Dusty Chalk]

'Dimed'? Maxed? That's funny, that's the way I usually play my MDT, I was just naturally drawn towards that configuration.

Yes, I have one of the Gramma stands. Was about to post an amp stands/Ikea coffee table/end table/footrest hacks thread asking what people did to get their amps/cabs up off the ground only a little bit, hadn't thought of an Isoacoustics for decoupling, but that immediately makes sense. I have a few such items to experiment with, maybe I'll try two of the larger ones on either side for starters.

The current amp stand I'm using -- On-Stage RS7000 -- tilts back too far for me to feel comfortable putting anything other than a non-combo cab on it. Even the MDT is too top-heavy to feel stable (plus the cats like to jump up on it, and would knock it over if they transferred any decent amount of horizontal momentum).

Thanks again for all the information -- it's especially helpful when someone else has real world experience with similar gear.

And yes, jfb, I've already driven one, possibly two, neighbors out from the apartment below me. It sat empty for the longest time, but the apartment complex management hasn't said anything, and I've never had the cops called on me, so I think I'm balancing on the line so far, and I stopped yesterday because the sun went down, so I do at least try to be a considerate neighbor. ;-p

 

[Boogie]

The current amp stand I'm using -- On-Stage RS7000 -- tilts back too far for me to feel comfortable putting anything other than a non-combo cab on it.

That's what I have and think it works perfectly for my 1x12 cab. The head sits in the ground in front because you're right: anything taller will fall or vibrate the hell off! It disconnects the cab from the ground, isolating the thunderous bass from the floor. That's a huge deal. Even though the amp is technically pretty damned loud, the lack of rumble fools everyone into thinking I'm under control. . Nothing could be further from the truth.

Anxiously awaiting the tone report.

 

[Dusty Chalk]

Don't hold your breath, my ears have been plugged up on and off (mostly on == plugged up) all day, so I don't trust myself not to overcompensate, and ( b ) I'm not a professional, I'm just an amateur with a few toys to play around with (and I'm an excellent shopper!). Oh, and ( 3 ) as I already explained elsewhere, I don't really have the experience with all the known gear that many of you all have, so you won't hear words like "tweed" or "plexi" or "British" or whatnot -- you'll probably get unorthodox descriptors like "squeaky" and "wide -- not 'thick', just 'wide'" and "fluffy doughy like angel food cake, not like New York bagels". (I'm making these up, these will not actually be in upcoming tone report.)

I do know what I like, though!

 

[Boogie]

There are a few real professionals around here and I ain't one of them. So if you like comparing tone to baked goods, I'm down with that. In fact, I'm kinda hungry now and might go change some strings.

 

[Dusty Chalk]

It's back (the ghost note, not the amp -- the amp never left).

I checked the tubes, again; they're still in place, though. I tried removing the back panel, get the fans away, see if "angle" changed anything, it didn't. Any ideas? I think it's actually lower than the original note, but it's most obvious on the high E string. I did try multiple guitars, just to make sure it wasn't the guitar. It's the amp. In fact, since I'm in recent acquisition of the Archon, I swapped exactly everything over to the Archon (including cables and cab) -- no ghost note there. It'd probably be fine if it was an exact harmonic, but hence the ring-modulator comment -- it sounds kind of discordant. I should try swapping the entire tube set maybe? I guess before that I should check the biases. Also maybe take it to Guitar Center, since that's where I got it from, talk to them about fixing it and/or returning it.

I'll try to get a recording of it. I'll send the recording to the PTC as well, see what they have to say.

 

[Boogie]

In my experience, anomalies like this are tube-related. And deny as they may, tubes are subjected to a lot of vibration in shipping/transport...something they don't always like. If you have spares, regardless of good tone or not, I'd swap every one and retest. I'd be very surprised if it's the amp.

 

[Dusty Chalk]

That's my primary suspicion as well. Not sure what the tube complement is, so not sure I have spares of everything, but will look. Heck, I even have a tube tester somewhere in this mess...I'm thinking maybe I should do this at Guitar Center, where I'm sure they have tubes a-plenty...

 

[Boogie]

Should be all 12ax7s and EL34s. Maybe a 12at7 but a 12ax7 will suffice for testing. Yank 'me from another amp for the test alone.

 

[Dusty Chalk]

That's almost exactly right...the one standout is the rectifier tube, GZ34 (5AR4), which I'm pretty sure I don't have in anything else or rolling around amongst my spares and backups.

 

[Dusty Chalk]

Okay, it wasn't the power tubes.

 

[Boogie]

Ghosting, in my experience, was a factor of preamp tube microphonics. It was also sensitive to vibration and got worse with louder volume and bass rumble. That's also why I put the head on the floor for gigs anymore. But at the same time, I've also had power tubes exhibit a similar sensitivity. If GC will help you debug the situation, that's where I would turn. But if not, I'd ask PRS' amp department for guidance.

 

[Dusty Chalk]

Okay I didn't realize today was day 30, so I returned it. Even though I just bought 3 12AX7s yesterday.

The guy plugged it in so I could show him what was wrong...and there was nothing wrong! He had the master all the way up to noon, and the volume around 9 o'clock, and it was still clean, nowhere near breakup, and not ridonkulously loud. It sounded great! What. The. Heck?

So now I feel bad (what's the opposite of buyer's remorse -- returner's remorse?), and that maybe I shouldn't have returned it. He thinks it was the cab, but I was using the PRS cab. The one thing he did different was he was using the 4 ohm jack -- the PRS 4x10 cabs are 8 ohm, aren't they? I was using the 8 ohm jack. I also had just popped the original tubes back in, and they weren't necessarily in the same order they were. If I use two of them (4x10s), I can use the 4 ohm jack, can't I? I do have two...hrm...what about the 2x12's, are they 8 ohm?

So...should I go back and buy it back? I'm actually really happy with the MDT and the Archon, so I don't really need it, but it did sound really good in the store, and it's a great price...