I recently picked up a pair of Nakamichi PA-7's. I'm very impressed with the performance from these units, and plan to keep them for quite a long time.
A couple of questions:
1) How similar is the PA-7 compared to the Threshold Stasis amps of that vintage?
2) What restoration steps should be undertaken to the PA-7 to ensure long trouble free life?
A couple of questions:
1) How similar is the PA-7 compared to the Threshold Stasis amps of that vintage?
2) What restoration steps should be undertaken to the PA-7 to ensure long trouble free life?
1) It was largely a copy using their own part #'s.
2) New electrolytic caps.
New caps it is. Thank you sir.
Since the original power supply caps are no longer available, I take it values that are close would work?
In addition to the caps, while you are at it, you might consider replacing the rectifiers and the bias controls.
This is what Jon Soderberg did on mine a couple of months ago, and I am very pleased with the results. I imagine most of the improvement came from the caps however.
Just a suggestion from a non-professional.
And thanks to NP for everything.
Yes indeed, thanks to NP is in order.
Thanks for the feedback. My buddy (who is very accomplished at restoration work) and I will get together to sort out what the best way forward. I think in general, the rectifier setup will be updated with HEXFRDs. Most, if not all, of the caps will be replaced as well.
I have the schematic of S150/higher models( differ by how many pairs of output transistors), It is similar, but Sxxx has cascode VAS and the bias spreader is different. That's the reason I ask. From Mr. Pass said, sounded like it's a straight copy. I just wonder are there any difference in sound between the Sxxx and PA-7.
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