Adcom GFA-5400

MKZ

I've just bought the Adcom Amp off the street thru craigslist. After I hooked up, I heard the low buzzy noise or hum(not sure what should I called it) from the right channel(most likely from tweeter). I had contacted the seller for the problem and he just ignored the calls I believe. I googled the problem and it seems like the ground loop problem with the electrical wires so I cleared out and tried. It still not helping it. I have also contacted the Adcom Service Center and they asked $75 just for estimates. My question is
- How can I fixed the problems?
- Is it worth it to bring it to Service Center?
- Should I junk it out on eBay to collect fund for new amp?
This is my 1st amp and any advice appreciated. Thanks.

snow

MKZ wrote: »

I've just bought the Adcom Amp off the street thru craigslist. After I hooked up, I heard the low buzzy noise or hum(not sure what should I called it) from the right channel(most likely from tweeter). I had contacted the seller for the problem and he just ignored the calls I believe. I googled the problem and it seems like the ground loop problem with the electrical wires so I cleared out and tried. It still not helping it. I have also contacted the Adcom Service Center and they asked $75 just for estimates. My question is
- How can I fixed the problems?
- Is it worth it to bring it to Service Center?
- Should I junk it out on eBay to collect fund for new amp?
This is my 1st amp and any advice appreciated. Thanks.

Well if it is a ground hum issue, it can be a real pain to locate it. have you ever noticed this hum before with your other equipment ? Personally i think it is most likely an issue with the amp not a ground hum if you hadnt noticed it before, and its only coming from one channel. as long as the speaker wires or rca and video connections arent crossed somehow with other wires on the right side.

You can try getting a surge protector and plugging (everything) into it then plugging that into the wall, that should elimanate a ground loop hum issue. also try plugging it into a different receptacle.

Sometimes video can be a real problem also, coxial cable is probally the worst offender for creating hums buzzes etc since it allready is grounded with its shielding, of course thats easy to tell if its the offender by taking the incoming coax away from the box or television for a sec. if it is then simply pull back the insulation so only the white plastic shows and the hard copper center,then reattach to tv or cable box minus the shielding.

I would also try switching speakers briefly to make certain it isnt an issue with the right hand one.

Last thing I would do is take it to a friends house hook it up to there system and see if the same problem occurs, if it does its the amp if not then its an issue with grounding.

As far as to whether its worth the cost to repair if its the amp, only you can make that decision. take what you paid for the amp + at least $75.00 add together and see if its worth putting the extra bucks in versus buying another complete amp.

REGARDS SNOW

MKZ

snow wrote: »

Well if it is a ground hum issue, it can be a real pain to locate it. have you ever noticed this hum before with your other equipment ? Personally i think it is most likely an issue with the amp not a ground hum if you hadnt noticed it before, and its only coming from one channel. as long as the speaker wires or rca and video connections arent crossed somehow with other wires on the right side.

You can try getting a surge protector and plugging (everything) into it then plugging that into the wall, that should elimanate a ground loop hum issue. also try plugging it into a different receptacle.

Sometimes video can be a real problem also, coxial cable is probally the worst offender for creating hums buzzes etc since it allready is grounded with its shielding, of course thats easy to tell if its the offender by taking the incoming coax away from the box or television for a sec. if it is then simply pull back the insulation so only the white plastic shows and the hard copper center,then reattach to tv or cable box minus the shielding.

I would also try switching speakers briefly to make certain it isnt an issue with the right hand one.

Last thing I would do is take it to a friends house hook it up to there system and see if the same problem occurs, if it does its the amp if not then its an issue with grounding.

As far as to whether its worth the cost to repair if its the amp, only you can make that decision. take what you paid for the amp + at least $75.00 add together and see if its worth putting the extra bucks in versus buying another complete amp.

REGARDS SNOW

Thanks. That's helpful. I also tried bi-amping with amp and receiver mix. There is not much noticeable noise but 2much bass and sounded not good since the driver has more amp then the tweeter has. I think the amp has the problem. I would try to take it to friends house this weekend too.
Any cheap and good sounding amp suggestions if I decided to go for another?

danger boy

I think the Adcom GFA-5400 is worth getting fixed.. I've had one for several years.. and it may not cost to much to get it fixed. The amp originally sold MSRP for $700 so it's no cheap-o amp. Big and heavy. Hum could also be coming from a bad interconnect in your system or the amp may have a broken solder joint.. that's very common in the 5400.

Chicomoralessxm

How are these amps by the way was considering one? Musically how would it match with the LSi9's or Era D5 compared to my other option the HaloA23

danger boy

i know the Adcom GFA-5400 isn't a good match for a 4ohm speakers.. which the LSi are. I'd look else where. When I was running my SRS's off this amp.. the yellow warning lights would begain to blink, not the red ones.. the red ones would have been fatal.. so I don't think they do well with speakers that require a lot of current. plus they run hot.

heiney9

danger boy wrote: »

i know the Adcom GFA-5400 isn't a good match for a 4ohm speakers.. which the LSi are. I'd look else where. When I was running my SRS's off this amp.. the yellow warning lights would begain to blink, not the red ones.. the red ones would have been fatal.. so I don't think they do well with speakers that require a lot of current. plus they run hot.

I don't know why you think this DB, other than perhaps an issue you have had with your particular unit. Adcoms will run a 4 ohm load all day long without issue. Adcoms are over built robust pieces.

The reason you may have been having issues with your SRS's is because the 5xxx series uses secondary windings which means they are not common ground and not compatible with SDA's unless you use the AI-1 connector (if your SDA's can). Another possible reason yours ran hotter than normal (which is pretty hot)

They run hot because they are heavily biased in class A and have a high idle current and since they are Mosfet based the heat is not an issue and totally normal.

I know for a fact the 5500, 5800, 5802 CANNOT be used with SDA's unless the AI-1 cable is used or the negative terminals are tied together (non-common ground). I suspect the same for the 5400.

All that being said, it's a matter of opinion if the Halo A23 is better. I'm a huge fan of Adcom amps and I'd say apples to apples, the A23 is a better choice. But I certainly wouldn't pay 50% more for it because it MAY NOT be worth it.

Just my .02c

H9

danger boy

H9, I wish I had kept the email from NAD, the 5400 Adcom amp is a common ground amp.. and at least in my experience with mine.. it did run my SRS's, but like at the borderline.. if I cranked them to much.. lights would begin blinking. that was my experience. so to avoid any possible damage to the SDA's or the amp.. i moved the Adcom to other amp duties.

So maybe mine was defective or something. I had it serviced twice in two years. I still have the amp.. but it's only being used as a surround speaker amp.

MKZ

danger boy wrote: »

I think the Adcom GFA-5400 is worth getting fixed.. I've had one for several years.. and it may not cost to much to get it fixed. The amp originally sold MSRP for $700 so it's no cheap-o amp. Big and heavy. Hum could also be coming from a bad interconnect in your system or the amp may have a broken solder joint.. that's very common in the 5400.

I have opened it up and checked the broken solder joint, surprisingly they are very solidly build with huge aluminum heat sink and big capacitors. I called the other service center and he asked $50 for estimates and it would usually costs around $200. Do you still think it worth fixing it?

danger boy

MKZ wrote: »

I have opened it up and checked the broken solder joint, surprisingly they are very solidly build with huge aluminum heat sink and big capacitors. I called the other service center and he asked $50 for estimates and it would usually costs around $200. Do you still think it worth fixing it?

certainly.. it's still worth fixing.. amps last a long time.. and they don't go out of date like say a pre amp will. See if the $50 can go towards the repair cost if needed.

MKZ

danger boy wrote: »

certainly.. it's still worth fixing.. amps last a long time.. and they don't go out of date like say a pre amp will. See if the $50 can go towards the repair cost if needed.

Yes, it is deductible if I fixed it there.
I actually bought this amp for my future LSi upgrades. I don't really need an amp for RTi4. Is this amp can still run for LSi7 or LSi9? The other post makes me confused a bit.

heiney9

danger boy wrote: »

H9, I wish I had kept the email from NAD, the 5400 Adcom amp is a common ground amp.. and at least in my experience with mine.. it did run my SRS's, but like at the borderline.. if I cranked them to much.. lights would begin blinking. that was my experience. so to avoid any possible damage to the SDA's or the amp.. i moved the Adcom to other amp duties.

So maybe mine was defective or something. I had it serviced twice in two years. I still have the amp.. but it's only being used as a surround speaker amp.

Fair enough DB . Good to know for certain the 5400 is common ground. The other higher power units in the 5xxx series are not, for future reference.

My original 545 just keeps chuggin along and has no problem pushing my 1C's beyond a level where I can't stay in the room for too long :eek: . Same for when I had my LSi-9's. Could I use a bit more current and power (maybe ) but it would be for show only.

Yes, MKZ it's worth getting fixed as long as the issues aren't too many. If I remember you said you bought this used off Craiglist. It's a crap shoot many times to know exactly what you are getting. Just like any other product abuse can make for difficult ownership. It takes a lot to cripple an Adcom but it can be done.

If you paid very little to get the amp it's certainly worth it to get it fixed from a reputable repair shop. Tyr not to open a whole other can of worms by taking it to someone who really doesn't know what they are doing, horror stories abound.

Good luck

H9

heiney9

MKZ wrote: »

Yes, it is deductible if I fixed it there.
I actually bought this amp for my future LSi upgrades. I don't really need an amp for RTi4. Is this amp can still run for LSi7 or LSi9? The other post makes me confused a bit.

Once fixed properly it should have no trouble with the load an LSi presents. Now if you have a very large room and you are trying to really crank, it might not be enough power, but for anything average to above average there should be no issue whatsoever.

H9

ViperZ

Adcom 5400 is an excellent amp. I was amazed with the sound stage changes when I added it to my HT to power RT1000p fronts. Is it worth $50+200 repair? Probably not... You should be able to get fully working 5400 for less than that (at least I did).

DarqueKnight

Please be aware that there are two versions of the GFA-5400: version 1 and version 2.

Working from memory, I do not recall what the differences are between ver.1 and ver. 2. I'll check later today. I also seem to recall an email from Adcom stating that all of their 5000 series MOSFET amps were non common ground.

I have owned two version 2 5400's and I still have one in my master bedroom system. I used a 5400 with the SDA CRS+'s in my home and work offices, but I eventually went to higher powered amps (GFA-5500 for the home office and GFA-555 Mk II for the work office) because the 5400's bass was a little lacking in impact with the SDA's.

heiney9

DarqueKnight wrote: »

Please be aware that there are two versions of the GFA-5400: version 1 and version 2.

Working from memory, I do not recall what the differences are between ver.1 and ver. 2. I'll check later today. I also seem to recall an email from Adcom stating that all of their 5000 series MOSFET amps were non common ground.

You know I thought I was correct but since DB owned one and we have had this discussion before with his particular 5400 I thought I might have been mistaken.

It's my understanding that the single torrid Adcom amps which use Mosfets (5xxx series) use a secondary winding to run the inputs (front end). The higher power units use a single torrid but use more than (1) secondary winding. Thus making it a floating ground and not comaptible with SDA's unless the neg. terminals are tied which can be done with those particular amps.

Disclaimer: Always check with the amplifier manufacturer in regards to common ground and tieing negative output terminals together.

H9

MKZ

Well, I'm just grab Adcom 5500 from tom t on the flea market. I think it is a good deal and hope it works fine.
One more question: what is the reasonable price for both buyer and seller I should ask for problem 5400?

danger boy

my 5400 never had a buzz in it.. so I can't say how expensive that would be to fix.. get an estimate... and go from there if the estimate is within reason you think.

DarqueKnight

My email to Adcom on 11/12/2000:

Subject: Adcom GFA-5802 with Polk Audio SDA-1B speakers

"Is the GFA-5802 a "common ground" amplifier? My speaker specifications state that only common ground amplifiers must be used. I just purchased a GFA-5802.
The sound from the speakers seemed "echoey" and out of phase. When I removed the interconnecting phase array cable from between the speakers, the sound was normal. I was previously using an Adcom GFA-555 amp and never experienced this problem. Any ideas on what is causing this?"

Adcom's response on 11/14/2000:

"There are 2 options for you to do. You can get a cable from Polk for those speakers, the AI-1 cable. This connects the 2 speakers and deals with the common ground problem. The other option is to take a piece of speaker wire and run it between the 2 negative terminals of the amplifier that you are using. This will not hurt the amp at all so dont worry about that. This a problem that has been common with the 5800, 5802, and 5500, all our newer amps and those model speakers.
Thanks and good listening
Adcom"

Page 1 of the GFA-5400 service manual states:

"Version 1 vs. Version 2

There are 2 versions of the GFA-5400 amplifier. The primary difference between the original version 1 and the updated version 2 is the addition of the ADCOM output protection circuit in version 2. This circuit can be noted by comparing the schematics of both versions in this manual. The power transformer, speaker binding posts and input jacks are also unique to each version."

Below are pictures of the ver.1 5400 on the left and the ver.2 5400 on the right. It is difficult to discern in the second picture, but the ver.2 binding posts are attached to a little plastic platform which is then attached to the case. The ver.1 binding posts are attached directly to the case.

The service manual does not mention this, but the case tops between the two versions are different also. Notice the ventilation slot patterns between the two pictures. The IEC jack in the second pic was installed by me.

danger boy

another thing is ver1 doesn't have a removable power cord, where ver2 does. mine is ver1

plus.. i think the 5400 is much older than the other 5XXX series of amps. IIRC

DarqueKnight

I have never seen a ver.2 5400 with a detachable power cord unless it was installed by the owner. I installed IEC jacks on both of my 5400's. The 5400 service manual specifies an attached power cord, but Adcom may have later converted to a detachable power cord similar to the 5500 and 5802.

MKZ

I think mine is version 1.

DarqueKnight

Yours is a version 2. Compare the rear panel RCA jacks, binding posts and case top to my version 2 pic above.

ka7niq

I have two Adcom amps, just sitting here.
One is an Adcom 585 http://www.empiricalaudio.com/frmods.html#Adcom%20GFA-585%20Mods
The other is an Adcom 2535 or 2235 or SOMETHING like that ?
It is a 2 or 3 or channel amp, or something like that ?
It is basically two Adcom 535's in a box.'
The Adcom 585 is a big **** amp.

I have SRS 2's with brand new RDO 194 tweeters, and I do not wanna fry em.
Will either amp work ?

The Adcom 585 is a terrific sounding amp on my B&W 801's.

Believe it or not, the two adcom 535 amp, whatever it is called sounded great on my old Klipsch Cornwalls

PSOVLSK

I bought a ground loop isolator from Radio Shack. About $20 and if doesn't solve the problem, return it. Maybe not the best solution, but it worked to my satisfaction.

MKZ

DarqueKnight wrote: »

Yours is a version 2. Compare the rear panel RCA jacks, binding posts and case top to my version 2 pic above.

You are right. I was looking at the detachable cord.
Let's say ver. 1.5.

MKZ

PSOVLSK wrote: »

I bought a ground loop isolator from Radio Shack. About $20 and if doesn't solve the problem, return it. Maybe not the best solution, but it worked to my satisfaction.

Good idea, I'll try every possible way this weekend.
Gound loop Isolator << is that the one you mentioned?
Thanks.

heiney9

ka7niq wrote: »

I have two Adcom amps, just sitting here.
One is an Adcom 585 http://www.empiricalaudio.com/frmods.html#Adcom%20GFA-585%20Mods
The other is an Adcom 2535 or 2235 or SOMETHING like that ?
It is a 2 or 3 or channel amp, or something like that ?
It is basically two Adcom 535's in a box.'
The Adcom 585 is a big **** amp.

I have SRS 2's with brand new RDO 194 tweeters, and I do not wanna fry em.
Will either amp work ?

The Adcom 585 is a terrific sounding amp on my B&W 801's.

Believe it or not, the two adcom 535 amp, whatever it is called sounded great on my old Klipsch Cornwalls

I believe the 585 is NOT common ground, but I honestly don't remember for sure. I had posed the question over at DIYAUDIO.COM as well a while back. The 585 is one helluva an amp. When I get sometime I'll see if I can find that thread over at diyaudio.com Might be quicker to call Adcom to know for sure. The 585 was a dual mono design which Walt Yung and Victor Campos came up with. It's a complicated beast and a huge departure from the 535/545/555 series (which is both good and bad).

H9

DarqueKnight

MKZ wrote: »

You are right. I was looking at the detachable cord.

The detachable cord was installed by me.

The fact that the hum is only coming from one channel, and the seller ignoring you, leads me to think that there is something wrong with the amp. Ground loops usually affect both channels.

The type of hum you describe can be caused by bad capacitors in the input circuit board. It could also be caused by a bad solder connection somewhere.

MKZ

That's very possible.
Update: I used my wife's out of state cell phone to call him and he just picked up. He was surprised it was me. I told him one of the channel is not working and want to give back since he was promised me that I can return it if there is anything wrong. He told me there is 8 fuses inside and take a look if it is still not working call him back and hang up. I think he's bs. Is it possible to check? I don't know where are those and how to get it change. Please take a look inside here.

Do you know where I can get the service manual you mentioned?

PSOVLSK

MKZ wrote: »

Good idea, I'll try every possible way this weekend.
Gound loop Isolator << is that the one you mentioned?
Thanks.

Yes. Hope it works for you.