I am now mostly done with this amp. I may see about a replacement power transformer, since the current one doesn't know the words to the songs (hums instead), but, other than that, I just plan to use it for a while.
There's not a whole lot left of the original parts, though. Besides all the original blown parts and electrolytics I replaced, I have replaced all the VAS 2n6556's with KSA1220A's (since they're available and pretty good devices). I also replaced the NPD5566 input JFETs with LSK389B's (lower noise, lower drift, and better matching - plus metal cans instead of platic DIP), and I replaced the TL081CP DC servo op amps with BB OPA27's (also lower noise) and I added offset trim pots to them so I could really tweak down the DC offset... it's about 2mV now.
By the way, the one other common transistor device in this amp that I did not replace, and thankfully don't need to replace, are the 2n8099's. I can't even find specs on these. Anyone know anything about them?
Cheers,
Paul
There's not a whole lot left of the original parts, though. Besides all the original blown parts and electrolytics I replaced, I have replaced all the VAS 2n6556's with KSA1220A's (since they're available and pretty good devices). I also replaced the NPD5566 input JFETs with LSK389B's (lower noise, lower drift, and better matching - plus metal cans instead of platic DIP), and I replaced the TL081CP DC servo op amps with BB OPA27's (also lower noise) and I added offset trim pots to them so I could really tweak down the DC offset... it's about 2mV now.
By the way, the one other common transistor device in this amp that I did not replace, and thankfully don't need to replace, are the 2n8099's. I can't even find specs on these. Anyone know anything about them?
Cheers,
Paul
2n8099
The 2n8099 and 2n8599 can probably be replaced by the Motorola MPS8099 and MPS8599 transistors. Bedini amplifiers use these same transistors in their differential input stage. Onsemi has this part.
http://www.onsemi.com/PowerSolutions/product.do?id=MPS8099
The 2n8099 and 2n8599 can probably be replaced by the Motorola MPS8099 and MPS8599 transistors. Bedini amplifiers use these same transistors in their differential input stage. Onsemi has this part.
http://www.onsemi.com/PowerSolutions/product.do?id=MPS8099
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