Adcom GFA 545 II mods

anatech

Administrator
Paid Member
2004-06-06 8:31 pm
Georgetown, On
He said a 5 amp ceramic.
Basically, it has lower resistance and doesn't change resistance as quickly due to heat. That is the basic reason for that.

I don't know what the rating is off-hand, but I would discourage anyone from exceeding that rating. Going to a slow opening fuse is giving more time for damage to occur should the amplifier go DC.

Mods on Adcom in general. Adcom already uses upgraded parts in their products, so there aren't any component swapping avenues unless you know precisely what you are doing and have the test equipment that can prove the amplifier still operates normally and within spec. "Upgrades" are responsible for more dead amplifiers and speakers than you can imagine.

What can be done? Super close matching of the input pairs and matching the output transistors. These are obviously something that takes technical skill and equipment. Hint: the transistor test function that gives you beta values isn't even close to being adequate for this job. There are some new output transistors from On Semi that will be very closely matched right from the tube these days.

Whatever you do, don't hack away at one of the better sounding amplifiers that Adcom produced. I used to do warranty service on these (and still service them), so I know the equipment very well. Doing this work is a PITA, so not easy no matter what a non-experienced person says. There are plenty of those out there.

-Chris
 

anatech

Administrator
Paid Member
2004-06-06 8:31 pm
Georgetown, On
Hi Mcass,
You could change the electrolytic caps on the driver board, but unless a resistor is out of tolerance, there is no reason to replace it. Adcom really did use good quality parts and replacing op amps could easily reduce the performance of one of these amplifiers.

The best you can do is use it nicely, don't let it overheat and enjoy it.

-Chris
 

Mcass

Member
2019-04-10 2:02 am
Ok do u recommend any specific caps I have built many amps mostly kits from China and I have had very good success but I’ve Learned how to do this stuff mostly from trial and error I’m a Newbe at best and don’t really no the reason for what goes where but I’m fairly good with a solder iron and have much time on my hands so would like to learn more about all of it any suggestions I have many pics I could also send of amps I’ve made would also like to learn how to upload them