Old Olympic audio tube amp

24kilo · 29th March 2006, 10:52 PM

Just bought a Olympic SA-812, I can't find anything on it. It has one 12AX7 and two 50C5's. I just changed the caps and it sounds great...But I want to use it for my Guitar amp and would like the Schmatics so I can mod the front end for overdrive. Any Help? Or can you tell me how this tube Config is laid out? BTW here's a pic

http://i21.ebayimg.com/05/i/06/85/65/c2_1_b.JPG

Eli Duttman · 29th March 2006, 11:39 PM

Based on the word "Stereo" on the front panel, I'm going to guess that there are 2 single ended channels using a 12AX7 section driver and a 50C5 "final".

The 50C5 data sheet suggests that the amp uses a series heater string and doesn't have a power transformer. That's both cheap and DANGEROUS.

Perhaps the best thing to do with that unit is canabalize the O/P "iron". Turning it into a safe guitar amp is probably not in the cards.

24kilo · 29th March 2006, 11:47 PM

I should have said, Sorry it's Mono. It says Stereo but it mono. The Speakers are inside. I've already grounded the chassis and no more floating ground.

Tom Bavis · 30th March 2006, 01:51 AM

OK, I have good news... and more good news.

First, I'm holding the schematic in my hand - a scan will cost you an email...

Second, it actually has an isolation transformer in it (assuming it's the same as the SA-813 and 814...) so it's somewhat safe...

...and some bad news - you'll need another tube to get enough gain for a guitar - maybe add a 12AV6 or 12AU6?

tbavis(at)rochester(dot)rr(dot)com

29th March 2006, 10:52 PM	#1
24kilo diyAudio Member Join Date: Aug 2005	Old Olympic audio tube amp Just bought a Olympic SA-812, I can't find anything on it. It has one 12AX7 and two 50C5's. I just changed the caps and it sounds great...But I want to use it for my Guitar amp and would like the Schmatics so I can mod the front end for overdrive. Any Help? Or can you tell me how this tube Config is laid out? BTW here's a pic http://i21.ebayimg.com/05/i/06/85/65/c2_1_b.JPG

29th March 2006, 11:39 PM	#2
Eli Duttman diyAudio Member Join Date: Apr 2004 Location: Plainsboro, NJ	Based on the word "Stereo" on the front panel, I'm going to guess that there are 2 single ended channels using a 12AX7 section driver and a 50C5 "final". The 50C5 data sheet suggests that the amp uses a series heater string and doesn't have a power transformer. That's both cheap and DANGEROUS. Perhaps the best thing to do with that unit is canabalize the O/P "iron". Turning it into a safe guitar amp is probably not in the cards. __________________ Eli D.

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29th March 2006, 11:47 PM	#3
24kilo diyAudio Member Join Date: Aug 2005	I should have said, Sorry it's Mono. It says Stereo but it mono. The Speakers are inside. I've already grounded the chassis and no more floating ground.

30th March 2006, 01:51 AM	#4
Tom Bavis diyAudio Member Join Date: Jun 2002 Location: Macedon NY	OK, I have good news... and more good news. First, I'm holding the schematic in my hand - a scan will cost you an email... Second, it actually has an isolation transformer in it (assuming it's the same as the SA-813 and 814...) so it's somewhat safe... ...and some bad news - you'll need another tube to get enough gain for a guitar - maybe add a 12AV6 or 12AU6? tbavis(at)rochester(dot)rr(dot)com