Static in Adcom GFA-5503, right channel

kuntasensei

After thinking I was hearing some noise from my right speaker during music, I swapped interconnects around and then swapped speaker cables between amp channels on the GFA-5503 until I confirmed that it's the right channel amp causing the problem. You can hear crackling with mid-bass, most obvious when you do a bass sweep on that channel, where the crackling goes in and out three times across the bass sweep.

For now, I've moved the center channel back to my AVR and am running the right channel off the center amp on the Adcom. Anyone know what could be causing this? Or is this something where I need to find someone to service my amp? I got this thing for a steal, so I'm not overly upset that it has this minor issue, but I would like to get it taken care of if possible. I could live with just running my towers off the Adcom, but the center sure did sound much nicer when running off the Adcom. Any ideas would be appreciated.

leroyjr1

Does it still do it once the amp is completely warm?

kuntasensei

Yup. The amp has been on for 3 hours now, and it's still doing it. I noticed a hum from that channel last week when I first powered it on, but it went away after about 10 minutes... but then I was checking levels with noise tones and noticed that the right channel was crackling today.

kuntasensei

I e-mailed Adcom's service address. Fingers crossed that it's a cheap fix! (Yeah... right...)

codyc1ark

I think they'll direct you to bigskyaudio if it isn't a warranty or production unit. IIRC...

heiney9

kuntasensei wrote: »

I e-mailed Adcom's service address. Fingers crossed that it's a cheap fix! (Yeah... right...)

It's like a car repair, nothings cheap and the labor is the most costly. Plan on at minimum $100, probably more. Probably some caps hopefully not output trannys.

H9

kuntasensei

A guy I know here in town does repairs on pro-audio gear, but mostly for stage equipment. Is it worth taking it to him, or should I just see who Adcom directs me to? Not really keen on having to ship this thing, 'cause... it's freakin' heavy! :razz:

cnh

Brock might know. It is my understanding that Adcoms are not that hard to diagnose and repair in most cases. I have a guy who does all my work but he's been in the business for over two decades, a bit of a wizard with gear. He does both pro and home audio, though?

cnh

codyc1ark

I would assume your local guy can do it, if it's a bad cap or something along those lines, I'd have him freshen up the whole thing. Good luck!

kuntasensei

Haven't been able to get my guy on the phone, but I figured I'd crack the Adcom open just to look around. Everything looks really clean inside. I wiggled wires and made sure all the connections were solid.

None of the caps looked to be visibly bulging, but... there are 3 of them that when you press on the top, it feels like you're pressing bubble wrap. Two of them are for the right channel where the problem is. One is for the center channel, which isn't exhibiting any problems. I assume when you guys are talking changing out the caps, you're talking about the smaller ones, not the giant suckers that are under the main board, right? 'Cause those things look the size of Coke cans!

On a related note, I decided to crack open my Samson S1000 rackmount amp that I use for my SVS/Buttkicker setup, because I haven't particularly been happy with the sound lately. Sure enough, one of the caps in there looks like it's massively bulged on the top. It has been running 24/7 for like 7 years though... so I said screw it and ordered a Crown XLS1500 to replace it. Still gotta deal with the Adcom though, 'cause I totally want to keep it in service.

kuntasensei

Related note: I cancelled the order on the Crown. Took my ART-351 EQ out of the loop and suddenly my sub's punchy sound is back, even with that bulging cap. Makes me wonder what the hell is wrong with that EQ though, 'cause I had to turn the level down 8dB on the Samson with the EQ out of line to get it calibrated right again. I was only using the EQ as a subsonic filter for the SVS, so I guess it isn't necessary.

kuntasensei

Took the Adcom to my local guy, who said he just repaired two other Adcom amps last week. His initial impression is that there's a cold solder somewhere that's causing my static problem, but he did say it looked like a cap or two may have leaked onto the power assembly. He's gonna track down the static problem first then give me a price on refreshing all the caps. Seems like I'm in good hands, so keep your fingers crossed.

Also, after a night of **** with my Samson, it seemed to have its punch back with the EQ out of the loop... but nothing I did brought mid-bass back. It just doesn't sound as good as it used to. Re-did the order for the Crown XLS1500 and will be integrating that into my system tomorrow night to see if things improve with the sound of the sub. Hoping to have some news on the Adcom tomorrow. My Onkyo AVR handles my mains and center well enough... but man, I miss that Adcom sound. That's what I get for stepping into separates, 'cause now there's no going back! I blame all of you. :cheesygrin:

kuntasensei

I know at this point, I'm talking to myself here... but I figured I'd finish the story in case anyone ever reads it. The local guy threw the Adcom on a scope and was able to reproduce the static problem, and found that pressing against some of the solder connections on the amp for the right channel made it go away. He freshened up the soldering on several of the components and says it's showing a nice clean signal now. He's thinking that it may have been weakened in shipping and just didn't present itself until I had run it for a while. He has had it under load for several hours now without a hitch, just to make sure.

He also said that the caps are all fine. The traces he saw on the board that he thought could possibly be leakage from the caps were just heat/age-related. Gonna go pick it up after work and pray that all is well when I hook it back up tonight. Total cost: $75. If it is indeed fixed, I can not complain about that AT ALL. (Though I may still send it off to Big Sky Audio in August for an upgrade as a birthday gift to myself.)

Also, I got the Crown XLS1500 in place and that sucker controls my SVS -MUCH- better than the Samson did, especially with mid-bass near the crossover range. It actually seems to lend the SVS a very sharp attack to the bass and doesn't seem to ring as much with really deep bass. Threw some familiar material at it, and I'm pretty happy with the change. Watched How To Train Your Dragon to see how well it handles monstrously deep-trolling bass, and it put a big smile on my face! Should be interesting to hear how it sounds with the Adcom back on my mains and center.

leroyjr1

Thanks for the update. Was looking forward to your thoughts on the crown 1500 and glad to hear you're liking it.

Enjoy!

kuntasensei

Liking it is an understatement. I had to put the ART-351 EQ back in the loop to use as a subsonic filter around 18Hz, but I was clipping the input (with How To Train Your Dragon Blu-ray at -15dB from reference) unless I dropped the sub trim on my AVR to -8 and cranked the gain on the Crown up to two notches from maximum. When I got it to where it wasn't clipping the input on the ART-351, the gain was so high on the Crown that it was picking up audible noise that made it sound like my subwoofer was humming when nothing was playing. I set the Crown to filter out anything above 300Hz and that completely eliminated the noise (and since the AVR isn't sending anything above 120Hz to it anyway, I figured 300Hz was sufficient to prevent cascading of the two filters). Guess that's the fun of having a sub with external amplification.

Only ding against the Crown is that its on-board processing adds a bit of a delay, such that it added 2 feet to the detected distance of my subwoofer when I ran Audyssey. However, it blended more seamlessly with my other speakers than the Samson ever did, so I can live with that. One peripheral advantage is that the power meter on my Belkin PF60 now shows 1.2A with all my gear on instead of the 2.5A it showed when I had the Samson in there. Interested to see where it ends up once I hook the Adcom back up tonight. May be a negligible savings in power... but hey, anything to psychologically justify my upgradeitis. :cheesygrin:

kuntasensei

The verdict is: THE ADCOM IS FIXED! Came home, matched levels up to my other speakers, threw a 7-channel bass sweep at it - no crackling! Ran it through its paces with some Brian McKnight, Tal Wilkenfeld, and Nickel Creek... All solid. So hey, $75 and I didn't have to ship it anywhere! WHOO HOO!!!

(And for the record, my system is 3.6A at idle now with the Adcom running. Not awful, considering I could never get it to go higher than 7A before when I had Saving Private Ryan cranked.)

leroyjr1

Got any pics of your setup?

kuntasensei

Uh... nothing since the pics in my gallery, and the Adcom's not in those pics (though it now sits in the spot where all the DVDs on spindles are in the pics). I need to snap some new pics. Since those were taken, I've added the Adcom, changed out the Samson for the Crown, replaced my side surrounds with FXi30s, and replaced my height channels with RTi28s on angled brackets.

kuntasensei

Well, that was short-lived. Static came back in the Adcom's right channel... Then the center channel dropped in level and has zero bass, which makes me wonder if a cap just died. So not only is the original problem not fixed, but now I have a new problem!

Gonna give local guy one more crack at it, then it's going off to Big Sky Audio. BLAH!!!!

kuntasensei

Today's external amplification lesson: If you accidentally pull off an interconnect while you have a noise tone playing, don't just plug it back into the amp without stopping the noise tone... because it's a good way to blow the rail fuses. (Yes, I'm an idiot... That's what happened to my center channel amp last night when I was swapping cables around. OOPS!)

My local tech put the right channel on a scope with me there this time, after he replaced the fuses for the center channel and tested it. On a scope, it isn't showing any hum or noise on the right channel, nor could we hear anything when he plugged it to a speaker on his bench and ran a frequency sweep. But it still has the intermittent hum/static when I hook it to any speaker at home. It's the most confusing thing! Gonna go home and do some cable routing to see if it's some bizarre interference problem... and if that doesn't work, I guess Big Sky Audio's gonna get their hands on it for repair and restoration. (Remind me again why I got started down this road... Heh...)

Oldfatdogs

(Remind me again why I got started down this road... Heh...)

Because when all the bugs are worked out,you sit in your room and smile ear to ear when the music starts to play.
That' what audio is all about Charlie Brown .:cheesygrin:

kuntasensei

Yeah... when it works, it sounds amazing! I just can't figure out this stupid noise in the right channel! All that's on that side of the rack is a 4-port 10/100 switch, and the cords are nowhere near the speaker cable or ICs. I guess I need to get back there and just reroute everything.

Oldfatdogs

Keep at it you will find the problem.Dan

kuntasensei

Well, when I got it back home, I shifted my cables around and moved everything away from the ICs and speaker cables as much as possible. This time, I plugged the center into the right channel of the amp and the right into the center channel of the amp. Powered up, no noise and sounds great. Powered it back down and back up after about 10 minutes (since this has been an intermittent problem), and all was well. I also added a 15-second delay to both of my amps on my power center so they are the very last thing to come on. Hopefully, the noise won't come back. Fingers crossed!

Drenis

George Grand suggested once to me to try and apply a clockwise twist while pressing in on the IC's to see of there were noises or any change to sound. Can identify a cold joint. You may have already tried that...

kuntasensei

No, I sure haven't... but if it starts making noise again, I'll give that a whirl. :razz:

kuntasensei

Eh, I give up. The noise/static came back tonight. Tried twisting the ICs, turning it off and on, etc. to no avail. There is just something very bizarre happening here. If you turn it on and don't hear the humming/crackling, it works like a champ no matter what you throw at it. But if you power it up and it starts that noise immediately, it never goes away, even if you turn it off and on. Turning it off and on makes it clear up a little... but doesn't fix it. But if I wait until tomorrow and power it up, odds are that it will be fine.

So for now, I give up. Running my mains off the left and center channels, and running the center off my AVR again. Since the problem is so oddly intermittent and it never does it when I take it in to my local shop and it's on a scope, I think I'm just going to keep using it as-is until next month or so, then shoot Big Sky Audio a message and do the full repair/upgrade on it.

leroyjr1

Did you try contacting the seller?

kuntasensei

Nah... I bought the thing as-is, and with the age of the amp, I kinda' figured it would eventually need some maintenance. I figured it was just a roll of the dice. And hey, it worked fine for a few months! He wouldn't be able to tell me anything anyway, 'cause he had bought it from someone else and had it in a closet for over a year for a system he never put together.

GlennDog

Just curious. . . . Where are you at on this issue? Also, in post #1 you got it for a steal. May I ask, how much? As I've got a line on one, and I'm trying to determine fair market value, THANKS!

btw I know the wait will be worth it after it's freshened-up

G

kuntasensei

I paid $450 for it. As far as where I am with the issue, my local guy wanted one more crack at it. He thought he had found the problem, and when I got it back home, it worked for 5 days... before the problem arose again. It's currently sitting disconnected in my rack until I decide what I want to do with it. There's a guy about an hour away who does Adcom work and says he can definitely fix it for $115 + parts... so I'm trying to decide if I want to do that or just send it off to Big Sky for the full upgrade treatment.