Any info on old "Cosmos" amp'?

Jonathan Bright · 2nd August 2005, 03:48 AM

Does anyone have any info' about a "Cosmos" amp. (Not the new huge version reviewed in Stereophile) It is about 40 yrs old. Uses a pair of 6BM8s in each output stage. (around 6-7 watts) It is an intergrated/hybrid model with a pair of Germanium transistors runing off a negative supply rail for the mag' preamp.

gingertube · 2nd August 2005, 05:19 AM

Jonathan B,
I did a restoration on one of these about 5 years back and sold it to one of my apprentices (at the time) who has been using happily ever since (for $100).

I'm not at home at the moment having been posted from Adelaide to Cairns (your kneck of the woods) for 4 weeks work on the Navy Laser Airborne Depth Sounder. Back in Adelaide 10th August.

If you haven't got any info by then pm me - I'm fairly sure I have a full circuit trace in my "Resurections" file at home. I can photocopy and send to you.

From memory I had trouble with leaky coupling caps (those Toshiba Oil Caps) and ended up replacing the lot. This had dragged output tube grids high (6BM8s as you rightly state) and had cooked the tubes. Also did the usual replacement of all electrolytics.

Cheers,
Ian

Jonathan Bright · 2nd August 2005, 06:43 AM

Thanks for prompt reply. Mine has a "dodgy" output trany. of all things. No rush, will catch up when you're back at the City of Churches. Thanks again, Jonathan

2nd August 2005, 03:48 AM	#1
Jonathan Bright diyAudio Member Join Date: Feb 2004 Location: Queensland	Any info on old "Cosmos" amp'? Does anyone have any info' about a "Cosmos" amp. (Not the new huge version reviewed in Stereophile) It is about 40 yrs old. Uses a pair of 6BM8s in each output stage. (around 6-7 watts) It is an intergrated/hybrid model with a pair of Germanium transistors runing off a negative supply rail for the mag' preamp. __________________ "It was the Spring time of the year when aunt calls to aunt like mastodons across the frozen waste." P.G. Wodehouse.

2nd August 2005, 06:43 AM	#3
Jonathan Bright diyAudio Member Join Date: Feb 2004 Location: Queensland	Thanks for prompt reply. Mine has a "dodgy" output trany. of all things. No rush, will catch up when you're back at the City of Churches. Thanks again, Jonathan __________________ "It was the Spring time of the year when aunt calls to aunt like mastodons across the frozen waste." P.G. Wodehouse.

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2nd August 2005, 05:19 AM	#2
gingertube diyAudio Member Join Date: Oct 2004 Location: Adelaide South Oz	Jonathan B, I did a restoration on one of these about 5 years back and sold it to one of my apprentices (at the time) who has been using happily ever since (for $100). I'm not at home at the moment having been posted from Adelaide to Cairns (your kneck of the woods) for 4 weeks work on the Navy Laser Airborne Depth Sounder. Back in Adelaide 10th August. If you haven't got any info by then pm me - I'm fairly sure I have a full circuit trace in my "Resurections" file at home. I can photocopy and send to you. From memory I had trouble with leaky coupling caps (those Toshiba Oil Caps) and ended up replacing the lot. This had dragged output tube grids high (6BM8s as you rightly state) and had cooked the tubes. Also did the usual replacement of all electrolytics. Cheers, Ian

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