Building the Perfect Cmoy for Grado SR 225s
Apr 1, 2008 at 12:35 PM Post #16 of 18

Originally Posted by FallenAngel /img/forum/go_quote.gif
...with the smoothness (forced rolloff via Solen 4.7uF input caps) is adding some some necessary punch and warmth...

How do these caps add punch? I mean, they are coupling caps, if they forcibly roll off something, it is low frequencies (doesn't punch come from down there?). Besides, if the caps are this big, the low-frequency roll off is pushed well below the audio band. So how do these caps force smoothness?
Apr 1, 2008 at 1:16 PM Post #17 of 18
Thanks for the link. I am at work and pictures don't come thru so I will have to look at this when I get home.

Thanks again.
Sep 4, 2013 at 12:57 PM Post #18 of 18
I have read yours post on these thread
I am curious about yours observation about amps for grado headphones.
I have grado sr80 and regular cmoy amp.
Can you tell me something more about ra1 amp .
Is there any improvement  because of 2x9v battery supply
You said that ra1 is bether than r47 headphones amp
Can you explani more about that.
My source is xonar dx sound card and i have noticed significant improvement in bass with cmoy because output impedance of xonar is 100 ohm and cmoy have far less impedance.
Is current only important thing for chosing amp for grado ?
Do you maybe have pcb layout for grado ra1 or grados clone
Greetings from Serbia :)
headphonejunkie, the schematic can be found on the link NiceCans posted, which is page one of this very thread.

It's a fairly straight forward build. The schematic is basically a cmoy with huge 5.1uF Solen input caps and .1uF power supply bypass caps.

I'll mention it again that it's been my experience that even the resistor values play a role in the sound of the amp. Don't have an explanation, but the closer you get to the original, the better.

FallenAngel, I have a Benchmark DAC1 (usb version) running off a balanced isolation transformer that sounds fantastic with my 125's, but sometimes I prefer my RA-1 clone. I totally agree with you that the combination of opamp and input caps is what makes this amp sound good with Grado's. This is why I feel it's the "Perfect Cmoy for Grado SR 225s."


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