Old Fisher SA-300 Amp help!

KP11520 · 16th March 2011, 02:45 AM

Hi Gang!

A friend has found a Fisher SA-300 Tube Power Amp that is without tubes and he needs a Schematic to get some help from an experienced Guitar Amp friend.

Can anyone make any recommendations for the Schematics and/or Tubes and/or Gotchas.

Thanks as always in advance!

Eli Duttman · 16th March 2011, 03:12 AM

You can get the schematic from HIFI Engine, after registering.

The tube complement is 2X 12AX7/ECC83s, 2X 12AU7/ECC82s, 2X matched pairs of EL34/6CA7s (4X power tubes total), and 2X 5AR4/GZ34s.

BTW, Fisher's 45 WPC claim is HIGHLY optimistic. That comes from before FTC rules were put in place. A yield of 35 WPC RMS is about right from a PP pair of EL34 family tubes.

KP11520 · 17th March 2011, 03:36 AM

Thank you Eli.

Always a Gentleman here!

I saw 30 WPC in a few references. They seemed to held in high regards for an early 60's amp.

Hopefully, he'll join HiFi Engine and download it but I think he might have tried that and found what they had wasn't complete.

I'll check with him.

Thanks again!

Regards//Keith

16th March 2011, 02:45 AM	#1
KP11520 diyAudio Member Join Date: Apr 2007	Old Fisher SA-300 Amp help! Hi Gang! A friend has found a Fisher SA-300 Tube Power Amp that is without tubes and he needs a Schematic to get some help from an experienced Guitar Amp friend. Can anyone make any recommendations for the Schematics and/or Tubes and/or Gotchas. Thanks as always in advance! __________________ If Wile E. Coyote had enough money to buy all that ACME ****, why didn't he just buy dinner?

16th March 2011, 03:12 AM	#2
Eli Duttman diyAudio Member Join Date: Apr 2004 Location: Plainsboro, NJ	You can get the schematic from HIFI Engine, after registering. The tube complement is 2X 12AX7/ECC83s, 2X 12AU7/ECC82s, 2X matched pairs of EL34/6CA7s (4X power tubes total), and 2X 5AR4/GZ34s. BTW, Fisher's 45 WPC claim is HIGHLY optimistic. That comes from before FTC rules were put in place. A yield of 35 WPC RMS is about right from a PP pair of EL34 family tubes. __________________ Eli D.

17th March 2011, 03:36 AM	#3
KP11520 diyAudio Member Join Date: Apr 2007	Thank you Eli. Always a Gentleman here! I saw 30 WPC in a few references. They seemed to held in high regards for an early 60's amp. Hopefully, he'll join HiFi Engine and download it but I think he might have tried that and found what they had wasn't complete. I'll check with him. Thanks again! Regards//Keith __________________ If Wile E. Coyote had enough money to buy all that ACME ****, why didn't he just buy dinner?

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