Dealing with Gremlins

[Scott_F]

I had an amp on the bench for a long time for many different reasons, some personal, some professional (time), blah blah blah. I had an amp that had an ungodly hum in it that I spent some time tracking down. It wasn't a really bad hum, but an annoying one that was just pissin' me off. Hum in an amp is unacceptable. I finally figured it out. But with all the time spent on it, I could have built a 2nd one. :smack: The good news is that if I ever hear it again, I'll definitely know where to look first.

Nothing like gaining experience the frustrating way! :eek13: I hate it when gremlins invade my work bench.

 

[cream123]

Re: Dealing with Gremlins

where was the problem?

 

[B Bent]

Re: Dealing with Gremlins

Cool!!! And not so cool!!! I am glad its done and will be on my way tomorrow!!! I'll break it in right come Wednesday too!!!!

 

[the guy who invented fire]

Re: Dealing with Gremlins

Odd ball noise can be a real pain in the back side...Im glad you got it and Im also glad it's on the way.

 

[B Bent]

Re: Dealing with Gremlins

Odd ball noise can be a real pain in the back side...Im glad you got it and Im also glad it's on the way.

I bet you are glad!!! That means you'll get to give it a whirl too!! Thanks to you Christian I got bit by the Tweed bug once I saw and played your Super!!!

 

[the guy who invented fire]

Re: Dealing with Gremlins

I bet you are glad!!! That means you'll get to give it a whirl too!! Thanks to you Christian I got bit by the Tweed bug once I saw and played your Super!!!

Im less concerned about trying it out as I am just happy that now I don't have to hear you whine anymore!:chairfall

 

[B Bent]

Re: Dealing with Gremlins

Im less concerned about trying it out as I am just happy that now I don't have to hear you whine anymore!:chairfall

I haven't been whing too bad!! I am just being a typical gear junkie waiting for his next fix!!! Like I have said all along, I know it will be worth it once it lands!!!

 

[Jeff_H]

Re: Dealing with Gremlins

Scott...it's refreshing to hear that. I had a very respectable, nationally know builder of high end "hot rodded" Marshalls tell me just last year that modded Marshall's are just noisy and hum sometimes...and ther's nothing you can do about it.

I'm not talking about Jeff Seal, but the cicruit he hand built for me started to make some hum and pick up some radio interference and I took it to someone out here.

I didn't buy that excuse then, and I don't buy it now. Using my wireless system has eliminated the radio interference, but I still get some of the hum and noise at higher volumes...good thing I don't play that loud that often.

 

[Scott_F]

Re: Dealing with Gremlins

I won't speak for Marshalls as I've not worked inside any. Old amps will have hum especially if you've got carbon comp resistors in there. They just get noisy. But swapping in some new ones is pretty easy.

You gotta remember that I play in what amounts to an isolation room. I hear everything there. I also have 4 light bulbs in the ceiling fan kit in that room. They are all those little florescent things in there. I get some 60 cycle hum with my strat, but I know why.

But, hum in the amp, with nothing plugged in and all the volumes turned down to zero, well, that's just not good enough for me.

Like they say, that which does not kill me makes me stronger. I did learn a lot more about the ins and outs of tweed circuits and that's always going to be a good thing. Thanks to the intenet, I have mentors like Randall Aiken, Bruce Collins and Gerald Weber. I ended up completely redoing the grounding scheme on this bad boy. I like it so much that I'll probably use it 100% of the time from now on.

I easily spent 12 hours on it yesterday and 6-7 more on it today. I darn near rebuilt it completely.

 

[Scott_F]

Re: Dealing with Gremlins

Oh and Jeff, I hear that Trainwrecks are noisy by nature. If so, that amp might never make it off my bench.

 

[Jeff_H]

Re: Dealing with Gremlins

Oh and Jeff, I hear that Trainwrecks are noisy by nature. If so, that amp might never make it off my bench.

That's why I'm glad you're building it...because if you proclaim it done, then I know it will be good. If not, the search will continue.

Oh, and the only original Marshall components inside my amp are the trannies and tube sockets. Mr. Seal replaced everything else....everything.

 

[LesStrat]

Re: Dealing with Gremlins

And where is Mr. Seal, anyway? He's a great guy.

Oh, yes. Glad you figured it out, Papa Smurf.

 

[B Bent]

Re: Dealing with Gremlins

I am gonna pipe in and vouch for Scott on the whole quiet amp thing. my 1st Celtic was absolutely 1000% whisper quiet at idle. That's the way it has to be for me!! I am pretty annoyed by crazy noises in amps.

 

[PUCKBOY99]

Re: Dealing with Gremlins

Hey Jeff, FWIW, the Edana is EXTREMELY quiet.....especially compared to the few Marshalls I've had.

Actually, it was the 1st thing I noticed :bigok:

 

[Gr8Scott]

Re: Dealing with Gremlins

My Edana is as quiet as a mouse fart at 1,200 paces (until I hit the strings of course...).

 

[PUCKBOY99]

Re: Dealing with Gremlins

Well, I never quite measured out the 1200 paces.....but I guess it to be pretty damned close :laugh2:

 

[joelap]

Re: Dealing with Gremlins

Scott, I hear ya on the Gremlins. I've got a 1968 plexi clone sitting here and the phase inverter voltage just wont go right. Oddly enough, it was correct for about 3 minutes yesterday, then as I got to measure pin 8, the voltages went back to the incorrect ones from before. All my caps are oriented correctly and all my resistor as the correct value. It's killing that I've got this thing all done and cant get it fired up yet. So It's gotta be wired right to get the right voltages for at least 2 minutes, but somethings gotta have a cold solder joint or be touching somewhere. But there's no sparks or sound to signify anything significant so I have no idea.

PS: how difficult was the DC-30 to build? Compare it to a JTM45/100 or 12xxx series plexi built? I think that's next on my list. The soundclips on matchless.com make me wanna scream

 

[kmcguitars]

Re: Dealing with Gremlins

I just had my Princeton on the bench for 2 weeks trying to find the low end buzz gremlin I was having? Removed ALL mods Completely back to stock NOPE!Replaced all Electrolytic decoupling caps...NOPE. Changed the coupling cap from the Preamp to the PI from a .022 to a .0047...NOPE. Changed PI coupling caps from .1 to .022...NOPE. After all that stupidity... It seems to be the baffle board.:smack: Like wise... My 2204 Homebrew had a oscillation problem that magically disappeared one day?

 

[noth]

Re: Dealing with Gremlins

I won't speak for Marshalls as I've not worked inside any. Old amps will have hum especially if you've got carbon comp resistors in there. They just get noisy. But swapping in some new ones is pretty easy.

You gotta remember that I play in what amounts to an isolation room. I hear everything there. I also have 4 light bulbs in the ceiling fan kit in that room. They are all those little florescent things in there. I get some 60 cycle hum with my strat, but I know why.

But, hum in the amp, with nothing plugged in and all the volumes turned down to zero, well, that's just not good enough for me.

Like they say, that which does not kill me makes me stronger. I did learn a lot more about the ins and outs of tweed circuits and that's always going to be a good thing. Thanks to the intenet, I have mentors like Randall Aiken, Bruce Collins and Gerald Weber. I ended up completely redoing the grounding scheme on this bad boy. I like it so much that I'll probably use it 100% of the time from now on.

I easily spent 12 hours on it yesterday and 6-7 more on it today. I darn near rebuilt it completely.

Without a doubt, getting rid of hum and buzz in amplifiers can be more difficult than designing the rest of the damn thing!!

Noth

 

[lastwinj]

Re: Dealing with Gremlins

bummer