$300 amp versus $3000 amp ???

[JoeE SP9]

A lot of the current craze for older (vintage) Japanese receivers seems to be a result of comparing one of those old heavy workhorses against one of the new flimsy lightweight examples. Looked at in that way there is no comparison.
As far as any of them against an Adcom GFA-545 there is no comparison. The Adcom flat stomps all over them in clarity, detail and transparency. As far as bass goes they are simply in two different ballparks. The Adcom has bass that approaches true high end quality and character. The vintage receivers merely have nice bass.
If you want to improve an Adcom to the point of being a contender there are a few things you can do.
1. Replace the resistors with Vishay's
2. Replace the capacitors with Infinicaps or Musicaps or any other high quality caps.
3. Replace the rectifiers in the power section with high speed diodes.
4. Increase the power supply capacitance.
5. Replace the input connectors.
Optional
Change the AC cord to an IEC connector.
You have no idea how good the basic design of an Adcom is until you've heard one with upgraded parts.

[GMichael]

A lot of the current craze for older (vintage) Japanese receivers seems to be a result of comparing one of those old heavy workhorses against one of the new flimsy lightweight examples. Looked at in that way there is no comparison.
As far as any of them against an Adcom GFA-545 there is no comparison. The Adcom flat stomps all over them in clarity, detail and transparency. As far as bass goes they are simply in two different ballparks. The Adcom has bass that approaches true high end quality and character. The vintage receivers merely have nice bass.
If you want to improve an Adcom to the point of being a contender there are a few things you can do.
1. Replace the resistors with Vishay's
2. Replace the capacitors with Infinicaps or Musicaps or any other high quality caps.
3. Replace the rectifiers in the power section with high speed diodes.
4. Increase the power supply capacitance.
5. Replace the input connectors.
Optional
Change the AC cord to an IEC connector.
You have no idea how good the basic design of an Adcom is until you've heard one with upgraded parts.

Can you still call this amp an Adcom after all this? Seems like you are building an amp from scratch and just keeping the shell it came in.

[JoeE SP9]

Can you still call this amp an Adcom after all this? Seems like you are building an amp from scratch and just keeping the shell it came in.

You are probably right. What started out as small as changing the input coupling capacitors mushroomed over a period of years to what I have now. I haven't made any changes to the actual circuit designs just replaced most of the components with higher quality ones. My Dyna MK-III's are more in the line of new amps. The only thing they have in common with the originals is the transformers and the choice of output tubes. I designed new hard wired input driver boards (no PCB) using a 6CG7/6FQ7 as a driver and a 12AT7 as a phase splitter. I had experimented with a solid state power supply but it needed a soft start circuit to allow easy tube warm up so I went back to a GZ34 rectifier tube. The RCA tube manual (out of print) has been invaluable for any kind of tube design work. I have used high quality parts with my MK-III's also.