I wish you tube was around when I was 16 watching you and being interested in electronics and hifi even now at middle age I would have taken electronics up as a perfession I really like the way you explain how all the items interact with each other thank you for taking the time to show people like myself how these amps actually work I have alot more respect when turning on my amps and pre amps thanks to you Sir .🙏
Electronics as a profession is a whole lot different than what this dude is doing, repairing this power amp. IN THIS DAY AND AGE, they would more than likely throw this Amp in the garbage. Component repair is a thing of the past, These are the true words from an EE.
@@jacktaylor1030 BS! Anybody that knows anything about audio equipment can tell you that these simply bring in between $500 up to $1,000 or more per unit. They are highly regarded and well sought-after. Next time know what you're talkin about before you start spitting out BS! Collector of Hi-Fi for over 40 years here so don't even try!
Excellent rebuild. I recall my first encounter with these Adcom 5 series back in the eighties at a local hifi shop. As a demo they would power up these monsters and drive the Infinty Kappa 9 towers. A very powerful experience. To add some novelty, they would also cut the power to the amps while still running. I swear the signal would still be coherent and audible for 20 or 30 seconds afterward. This kind of power for around a kilobuck point was a hoot! Really nice watching you resurrect them so masterfully.
You've achieved an impressive in-room sound with no apparent coloration or distortion. I used to own a GFA-535 so I know the clean, clear Adcom house sound quite well.
I had an Adcom GFA-555 back in the late 80's. I sold it in '97 or '98. I never had any issues with it, so perhaps I was lucky. I really did like the amp a lot. Great rebuild.
Just wanted to say how much I enjoyed this series of videos. You really did an amazing and fine job on the amplifier and your explanations were so valuable. What a piece of crap it was too! I just can’t believe how bad it was when you first showed it. You sure made your case that these really aren’t really financially viable and cost efficient to buy and rebuild. This was such a great series and fun to watch, thank you. Buddy
Wow, that channel got completely destroyed! It's rare for the heatsink-mounted thermal bias compensation transistor to be burned out. You could also use KSP42, but the one you chose is good too. You'll notice there is also a PNP type thermal compensation transistor mounted on the input board. I think the idea is to kind of get an average of the board temperature and the output module temperature. In the GFA-565, both of these comp transistors are mounted in the output modules, one for each PNP and NPN module.
That was incredible. Watched all 3 in a row Man I wish you could do that to mine. I have the 585 like you just fixed , and a pair of 565’s , and three 555’s. I’ve been holding on to these for about ten years and want them working like the one you just fixed. I still have hope , especially after watching this !!
Great vid! Many of the principals here are very similar to my Phase Linear PL400's. I brought one back from the dead, but shelved it because I was unable to get the idle current within spec on one channel. Probably why the previous owner gave up on it because it kept blowing outputs. I'm a lot smarter on this stuff then I was a few years ago..Your channel has been a great help! Thanks Tony!
These are great and I believe any audiophile who's witnessed one functioning in the past will enjoy these adcom vids. thanks for doing what so many of us wish we could. I've long daydreamed of being able to afford one in decent shape, now I dream of doing the rebuild you have completed here. In my opinion yours is better than new. I hope you can enjoy it for years to come. Also, if you ever decide to part with it... VERY INTERESTED. LOL. kutgw
Hi Tony. Thank you for the great video series. The fact that you've done the whole rebuild successfully, and you state you've not done such a complex job before, gives me the courage to try and expand my range of repairs. I'm in the process of restoring a Yamaha CR-1020. The main power board has been damaged by corrosive glue, so in addition to replacing the capacitors, I feel I should replace the transistors as long as I've got it torn down this far. Like you, I have run into trouble finding some of the transistors. The usual suppliers are not carrying them anymore, but I did find them on utsource. Do you or any of the viewers have experience with this online company? I'm leary because it's obviously a Chinese company, and I believe I've heard you make reference to "fake Chinese components." Thanks for your input!
love me some adcom amps! running the gfa 545 for my mid's and highs and a gfa 555 for the lows! rocks the house real nice no subwoofer needed lol also this beast will do 400wpc @ 4 ohms at 0.02 THD continuous power!
Amazing Knowledge and instruction, Thank you for this great video. I have a Adcom GFA-555 I would love you to check, I don't use at the moment because I am unsure of it's performance due to age. I think output transistor's would need to be checked. I don't have anywhere near the equipment you have. Thank you again for such great video's!
Rebuilt a GFA-555 mk II a couple years ago. Two of the main filter caps were pretty much shot (more than 40% capacitance gone). It's worth replacing them no matter how the measure. Nippon Chemicon U36 series are excellent replacements. I ended up selling it because I just could not get over the fear of torching my very expensive KEF speakers due to the lack of a speaker relay protection circuit. Also, the amp would send out some minor popping to the speakers on shut down as the filter caps discharged. I'm much happier with my NAD.
Great video as usual !!!! I bought 2 New Adcom GFA555II amplifiers back in 1994. I ran them in mono, each powering Polk Audio SDA1C’s. Sounded fantastic. Unfortunately I do not have the Adcoms anymore, but I do still have the SDA1C’s. A Denon POA2200 powering them. I do wish I still had the Adcom’s, but knowing the issues they can have, I am glad I do not have them anymore. I have looked into getting 2 more 555II’s, but after watching this video series, I think I will look into another option. Great video Tony !!! Awesome !!
The reason these amps are so good is they were designed by Nelson Pass of Pass Labs. A brilliant audio designer and enthusiastic supporter of DIY Audio. Love seeing the work you did here, fun!
HI - great work - thanks - just to let you know that you can create Playlists for the longer series repairs like the Pioneer F-28, 6 vid series I just watched - folk can just watch the lot in order then - cheers
Wow a very Educational video I have a GFA 555 mk2 I'm using on a pair of McIntosh Ls 350 witch are very nice speakers but I don't think I'll be using it very much longer cuz I can't replace them speakers it's a really nice match for the speakers and that mod you did looks expensive......I'm really kinda Aggravated I'm now going to have to buy another amp!!! I do not want to burn my McIntosh Ls 350 witch are pretty rare unreal
You ever try acetone for old thermal epoxy, it usually eats through most all resins and epoxies. I would only do this with the board removed from the heatsink though, you never know if acetone will break down other items...
i just now sat down and this popped up. good! the first comment also. rare :-) now all you need is an old B&K amp to make it's way across the bench. there was also a company called db systems that did some really nice sounding transistor amps. ever run across either of the two?
Thanks for the wonderful videos. I will surely open up my vintage Sumo and see if anything is leaked or rotten like you showed in your first video. My power amp gives a low hum. I tried by disconnecting the pre amp, but noise continued, then tried different cables, noise persisted. I read somewhere that problem could be from the big caps or from the power supply. Can I talk to you?
Wow. Amazing project. What would that rebuild cost?? I just had two 565 amps serviced. Both had corrosion but I'm hoping it wasn't as bad as this! Wish I could have sent you mine!
Great Video!! I have an ADCOM GFA-5800 with a faulty channel, I haven't been able to fix it, well I'm not an expert so that's expected but since I was able to fix other simpler Amplifiers I thought I would give this a try but this is not a simple Amp w/o the proper tools and expertise, any interest in repairing it?
What about BD131 as a temperature sense transistor, but what about MJ3055/MJ2955 matched pair for the output as well as BD131/BD132 matched pair as driver transistors.
Nice amp, grand video as always. BTW, why is a full power test hard on the Zobel network? Because it's attenuating at HF and therefore the resistor gets hot? Cheers - DA.
Followed everything clearly, still very uncertain how you handled the leaky, vented cap on the output transistor board. It looks like your finished amp is using the same board? It doesn't look like Hoppe's does not sell this board either. (I have a gfa-585 that has all these same issues, trying to decide to proceed)
I wish you tube was around when I was 16 watching you and being interested in electronics and hifi even now at middle age I would have taken electronics up as a perfession I really like the way you explain how all the items interact with each other thank you for taking the time to show people like myself how these amps actually work I have alot more respect when turning on my amps and pre amps thanks to you Sir .🙏
Electronics as a profession is a whole lot different than what this dude is doing, repairing this power amp. IN THIS DAY AND AGE, they would more than likely throw this Amp in the garbage. Component repair is a thing of the past, These are the true words from an EE.
@@jacktaylor1030 BS! Anybody that knows anything about audio equipment can tell you that these simply bring in between $500 up to $1,000 or more per unit. They are highly regarded and well sought-after. Next time know what you're talkin about before you start spitting out BS! Collector of Hi-Fi for over 40 years here so don't even try!
Excellent rebuild.
I recall my first encounter with these Adcom 5 series back in the eighties at a local hifi shop.
As a demo they would power up these monsters and drive the Infinty Kappa 9 towers.
A very powerful experience.
To add some novelty, they would also cut the power to the amps while still running.
I swear the signal would still be coherent and audible for 20 or 30 seconds afterward.
This kind of power for around a kilobuck point was a hoot!
Really nice watching you resurrect them so masterfully.
You've achieved an impressive in-room sound with no apparent coloration or distortion. I used to own a GFA-535 so I know the clean, clear Adcom house sound quite well.
I had an Adcom GFA-555 back in the late 80's. I sold it in '97 or '98. I never had any issues with it, so perhaps I was lucky. I really did like the amp a lot. Great rebuild.
Amazing how intelligent some people are that means you.
Tony, you're so right about the low-level detail this amp is capable of. It makes a great headphone amp!
Just wanted to say how much I enjoyed this series of videos. You really did an amazing and fine job on the amplifier and your explanations were so valuable. What a piece of crap it was too! I just can’t believe how bad it was when you first showed it. You sure made your case that these really aren’t really financially viable and cost efficient to buy and rebuild. This was such a great series and fun to watch, thank you. Buddy
Measures good congrats on the project. Time to blow the neighbors away? 😉
Wow, that channel got completely destroyed! It's rare for the heatsink-mounted thermal bias compensation transistor to be burned out. You could also use KSP42, but the one you chose is good too. You'll notice there is also a PNP type thermal compensation transistor mounted on the input board. I think the idea is to kind of get an average of the board temperature and the output module temperature. In the GFA-565, both of these comp transistors are mounted in the output modules, one for each PNP and NPN module.
That was incredible. Watched all 3 in a row Man I wish you could do that to mine. I have the 585 like you just fixed , and a pair of 565’s , and three 555’s. I’ve been holding on to these for about ten years and want them working like the one you just fixed. I still have hope , especially after watching this !!
Awesome job! Thank you for taking us on your journey.
Got to admit, I would have gotten those boards fully populated but that was an awesome find! Kudos to Poppy's Brain (hope I wrote that right)!
Great vid! Many of the principals here are very similar to my Phase Linear PL400's. I brought one back from the dead, but shelved it because I was unable to get the idle current within spec on one channel. Probably why the previous owner gave up on it because it kept blowing outputs. I'm a lot smarter on this stuff then I was a few years ago..Your channel has been a great help! Thanks Tony!
Great videos, please keep them coming. I'm learning a lot....
Glad to see this fixed, I had one blow up on me about 18 years ago, long gone now.
These are great and I believe any audiophile who's witnessed one functioning in the past will enjoy these adcom vids. thanks for doing what so many of us wish we could. I've long daydreamed of being able to afford one in decent shape, now I dream of doing the rebuild you have completed here. In my opinion yours is better than new. I hope you can enjoy it for years to come. Also, if you ever decide to part with it... VERY INTERESTED. LOL. kutgw
A great build and test, shows that if you take your time, it can be done!
Sir that is very impressive.seems like you have the patience of a saint.all kidding aside you did a great job.Pete
Thanks for the video and happy holidays to you too.
Good job Tony, love your attention to details
Nice teaching and very clear to the point from repair to Rebuild✌🏾2020 tech head...
What an awesome project!
Happy holidays to you.
Wow. You are very knowledgeable.
Nice Job, and Merry Xmas.
Thank you for the knowledge, great job!
Amazing Job :)
Thank you for your time :) very helpful information keep up your great work !!!
great job Tony
Hi Tony. Thank you for the great video series. The fact that you've done the whole rebuild successfully, and you state you've not done such a complex job before, gives me the courage to try and expand my range of repairs. I'm in the process of restoring a Yamaha CR-1020. The main power board has been damaged by corrosive glue, so in addition to replacing the capacitors, I feel I should replace the transistors as long as I've got it torn down this far. Like you, I have run into trouble finding some of the transistors. The usual suppliers are not carrying them anymore, but I did find them on utsource. Do you or any of the viewers have experience with this online company? I'm leary because it's obviously a Chinese company, and I believe I've heard you make reference to "fake Chinese components." Thanks for your input!
love me some adcom amps!
running the gfa 545 for my mid's and highs and a gfa 555 for the lows!
rocks the house real nice no subwoofer needed lol
also this beast will do 400wpc @ 4 ohms at 0.02 THD continuous power!
Amazing Knowledge and instruction, Thank you for this great video. I have a Adcom GFA-555 I would love you to check, I don't use at the moment because I am unsure of it's performance due to age. I think output transistor's would need to be checked. I don't have anywhere near the equipment you have. Thank you again for such great video's!
Love Adcom gear
Thanks for sharing it with us.
I find it interesting that the Marantz 2500 receiver drove 300 watts with much lower distortion. Those California designed receivers were amazing.
Rebuilt a GFA-555 mk II a couple years ago. Two of the main filter caps were pretty much shot (more than 40% capacitance gone). It's worth replacing them no matter how the measure. Nippon Chemicon U36 series are excellent replacements. I ended up selling it because I just could not get over the fear of torching my very expensive KEF speakers due to the lack of a speaker relay protection circuit. Also, the amp would send out some minor popping to the speakers on shut down as the filter caps discharged. I'm much happier with my NAD.
You could install a speaker relay board. I am sure the ADCOM is by far a better AMP
This was a great project. The only odd part was the listening test with a pic of the unpowered amp and preamp with the treble control cranked.
Nice work!
Awesome Job!!
Great video as usual !!!!
I bought 2 New Adcom GFA555II amplifiers back in 1994. I ran them in mono, each powering Polk Audio SDA1C’s. Sounded fantastic. Unfortunately I do not have the Adcoms anymore, but I do still have the SDA1C’s. A Denon POA2200 powering them. I do wish I still had the Adcom’s, but knowing the issues they can have, I am glad I do not have them anymore.
I have looked into getting 2 more 555II’s, but after watching this video series, I think I will look into another option.
Great video Tony !!! Awesome !!
The reason these amps are so good is they were designed by Nelson Pass of Pass Labs.
A brilliant audio designer and enthusiastic supporter of DIY Audio. Love seeing the work
you did here, fun!
I don't remember ever hearing Nelson working for Adcom!
HI - great work - thanks - just to let you know that you can create Playlists for the longer series repairs like the Pioneer F-28, 6 vid series I just watched - folk can just watch the lot in order then - cheers
Great Job!
The burn in is always “butt pucker “ territory for me when i have to use parts that aren’t totally similar..great job!
I don't see why. All you have to do is use a series light bulb or keep a close eye on the ammeter.
36:50 - Ah, Square-wave testing! It reveals a lot!
Love the VW bus. I'm a former Bus'er :)
Wow a very Educational video I have a GFA 555 mk2 I'm using on a pair of McIntosh Ls 350 witch are very nice speakers but I don't think I'll be using it very much longer cuz I can't replace them speakers it's a really nice match for the speakers and that mod you did looks expensive......I'm really kinda Aggravated I'm now going to have to buy another amp!!! I do not want to burn my McIntosh Ls 350 witch are pretty rare unreal
just have it recapped before it does become a problem like this one. this one had been used for awhile with bad caps before it fully failed
You ever try acetone for old thermal epoxy, it usually eats through most all resins and epoxies. I would only do this with the board removed from the heatsink though, you never know if acetone will break down other items...
i just now sat down and this popped up. good!
the first comment also. rare :-)
now all you need is an old B&K amp to make it's way across the bench.
there was also a company called db systems that did some really nice sounding transistor amps.
ever run across either of the two?
Excellent Video series, Did you make any for the GCD output line static or any output with noise. Thanks for making theses.
Thanks for the wonderful videos. I will surely open up my vintage Sumo and see if anything is leaked or rotten like you showed in your first video. My power amp gives a low hum. I tried by disconnecting the pre amp, but noise continued, then tried different cables, noise persisted. I read somewhere that problem could be from the big caps or from the power supply. Can I talk to you?
Thanks Tony! That was a lot of work. I wonder how many hours that you put into it?
Simple, honest Adcom amp design. Much better than all of that Carver mumbo-jumbo design/marketing smoke and mirrors....
Excellent as usual!
I will say that the constant ads are annoying and I miss your ad free videos
Really GREAT fix ! Amp looks better than new. I have to ask though, what's the mp3 player you use there at the end ?? I can't seem to locate one.
Awesome job do you sell any of your projects? Would love to own a piece of your work!
Wow. Amazing project. What would that rebuild cost?? I just had two 565 amps serviced. Both had corrosion but I'm hoping it wasn't as bad as this! Wish I could have sent you mine!
Very good job !
Great Video!!
I have an ADCOM GFA-5800 with a faulty channel, I haven't been able to fix it, well I'm not an expert so that's expected but since I was able to fix other simpler Amplifiers I thought I would give this a try but this is not a simple Amp w/o the proper tools and expertise, any interest in repairing it?
What about BD131 as a temperature sense transistor, but what about MJ3055/MJ2955 matched pair for the output as well as BD131/BD132 matched pair as driver transistors.
Nice amp, grand video as always. BTW, why is a full power test hard on the Zobel network? Because it's attenuating at HF and therefore the resistor gets hot? Cheers - DA.
Yes, it's mostly high power at high frequencies that's critical - and square waves contain particularly much HF energy.
Those are the holes for balanced inputs, why didn't you include in rebuild?
Now if you were to sell that Amp how much would you ask for it.
Followed everything clearly, still very uncertain how you handled the leaky, vented cap on the output transistor board. It looks like your finished amp is using the same board? It doesn't look like Hoppe's does not sell this board either. (I have a gfa-585 that has all these same issues, trying to decide to proceed)
Ive got a whole bunch of Adcom gear about 19 yo can you service it?
I owned a gfa 5500 and I could shut it off and it would continue to play for 30 seconds, alot of storage
Where are you located?