Yamaha C-65 thread

[satpaul]

Hello, after a long time I just report. Now it's the turn of the C-65.
First, the disassembly of the entire preamplifier,



Pavel

 

[satpaul]

And now a tour of the original parts.





Pavel

 

[satpaul]

Cleaning and replacement of all electrolytic capacitors. Cleaning of all switches, potentiometers.




Heatsinks screwed with M3 and insulating washer.



Pavel

 

[satpaul]

Replacement of all operational amplifiers and new rectifier diodes BYV16








Pavel

 

[satpaul]

All connections resoldered.




Pavel

 

[satpaul]

If anyone doesn't know what a cold connection is, here's a nice example.




Pavel

 

[satpaul]

And put everything together.





I ran the grounding cables underneath it.

Pavel

 

[satpaul]

Final completion.








Pavel

 

[satpaul]

Adjustment and test.





Done...

Pavel

 

[satpaul]

Please advise: what is the problem with my speaker popping when turning it on and off? I replaced the capacitor on the device's power switch with a new one of the same type.

Thanks Pavel

 

[avionic]

Please advise: what is the problem with my speaker popping when turning it on and off? I replaced the capacitor on the device's power switch with a new one of the same type.

Thanks Pavel

Shut power amplifier off first. Power up power amplifier last.
Other than that. I guess you could play with the muting transistor pairs. Located at the output of each of the flat amplifiers.

 

[satpaul]

Thank you avionic. The resistors on the coolers are 4k75 1%, I had them in a drawer.
Pavel

 

[avionic]

Thank you avionic. The resistors on the coolers are 4k75 1%, I had them in a drawer.
Pavel

I see that now 5-band color code.

 

[Soundscape]

Wow...

Best control amp thread I've seen. How does it sound with the new op amps?

 

[satpaul]

It plays amazingly. The deep bass is tight and short, the ultra-clear mids are not aggressive, the silky highs are very smooth, the overall sound image is extremely wide and deep. I was surprised by the identification of the instruments, almost 3D. I believe it will get even better over time.

Pavel

 

[satpaul]

Thank you for the praise.

Pavel

 

[Soundscape]

If I may ask...How many hours went into this? This would've taken me weeks to do, probably months.

 

[satpaul]

So I started on April 1, 2025 and finished on April 29, 2025. That includes ordering materials. Well, everything. Now it's going to be a month and it's starting to play out nicely.

Pavel

 

[satpaul]

Yamaha MX-1 + CX2

Hello everyone! This thread is a continuation of: https://audiokarma.org/forums/index.php?threads/yamaha-b2-and-quadral-vulkan-mk4.1070144/ So I brought home the MX-1 and CX-2, they are in good condition. Please note that I did not clean anything. First I tested a bit in the workshop...

audiokarma.org

I did something here too.

Pavel

 

[nakmandan]

Very nice work! You went one step beyond what I did to my own C-60 with replacing the OPAMPS. Which ones did you use and do you feel it was worthwhile to do this? Were you able to test or make any measurements from stock and note the differences? I also really like that you screwed the TO-220 heat sinks into place like I did. I don't understand why Yamaha didn't do this. The holes in the boards and threaded heat sinks are already there, why didn't they put a screw in there?!