keithrosenfeld :
Audiomano-
I saw in another section that you were looking for me (I co-founded Amber Electronics, which made the Series 70). Feel free to call me at work (434-220-0489) and I'll try to help.
- Keith Rosenfeld
Keith::
I an very happy for your reply. Thank you.
I own a pair of Series 70 amps which work wonderfully after all these years, only was neccessary some time ago to replace the aged 470 uF capacitors, which was done with audio grade non polar electrolytic ones of the same original values.
In another hand I have seen in internet a Series 70´s Schematic Diagram which shows 2 pair of 1.000 uF caps instead of one 470 uF pair. Here in this new schematic which it seems is a factory mod, one pair feed the LM391 N 100 and the other one, the driver transistors.
1.-Does this mod improve the already excelent performance of the amp?
2.-Can I incorporate it into my units?.
3.- Can I replace at least the 470 uF pair with a 1.000 uF new pair without problems like a surge on the LM391?.
4.- Does is neccessary to change the diodes too for this new capacitance?.
5.-The way I am using my pair is: removing the (+) (-) fuses in one channel on both amps to allow the entire power supply feed only one channel at time. The results are: a very natural sound of my Dahlquist DQ-10s particularly on strings chamber music. The series 70 were built like a tank. I love their musicality really.
Regards,