I had static one channel of my RA1 amp. Yesterday, I opened the box and melted the glue that covers the circuit board with a heat gun. I then was able to determine that one of the input caps was bad. Unfortunately while removing the glue, I obliterated the markings on the caps. I did measure 5 uF on the good cap but I decided to contact Grado for confirmation.
My email was answered within 2 minutes and the 5 uF value was confirmed. They also sent me a schematic of the circuit (basically a Cmoy with gain using JR4556 opamps). I replaced both caps with 2 uF Solens which I had on hand and all is well again.
Kudos to Grado for incredibly rapid response. OTOH the circuit is about as simple as you can get and the circuit could not cost more than $15.00 plus perhaps another $30 for the pot, audio jacks and power jack. I paid about $300 T 10 years ago. So the very nice wood box cost me about $250 - a very nice profit. The RA-1 works very well with the SR-60's which is all I need for occasional headphone listening.
Here's the schematic:
I married the perfect woman. The downside is everything that goes wrong is my fault.
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Topic - Talking about Grado - neolith 09:21:39 05/06/16 (4)
- RE: Talking about Grado - Awe-d-o-file 08:59:03 05/07/16 (0)
- Sounds like a deal to me... - Bill Way 12:33:17 05/06/16 (0)
- RE: Talking about Grado - genungo 10:45:01 05/06/16 (1)
- That mahogany housing sure does look classy, don't it? - neolith 10:55:11 05/06/16 (0)