Sansui RA-500 spring reverb

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jv
pushin' record
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Sansui RA-500 spring reverb

Post by jv » Tue Mar 04, 2008 9:58 am

So I recently bought one of these things with the intention of modifying it. One of the limitations of the unit is that you cannot get a "wet-only" output, and there is no wet/dry mix. So I got a schematic, and I figured out there IS a way to get a wet-only output without modification. What you do is plug the input into the left input, and take the output from the right output (or vice-versa). The reason why this works is that the L+R inputs are summed and fed into the reverb tank, which apparently has 2 springs. The 2 spring outputs are then summed with the original inputs and fed to the stereo output. So with no input on the Right, the right output consists only of the reverb signal. Also, the "reverberation time" knob should actually be called "reverberation feedback" because what it actually does is control the amount of signal from the output of the spring that is fed back to the input of the spring (which sort of makes the reverb time seem longer).
Anyway, I just thought I'd share this discovery in case anybody else has
one of these.
And it looks cool.

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Jeff White
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Post by Jeff White » Tue Mar 04, 2008 10:17 am

I bought one for $12 in 2004 (I think that exact model) and it sounds decent, however it is noisy. Hum in the output makes it unusable for me. Is this a simple cap job, or were these thing noisy to begin with?

Jeff
I record, mix, and master in my home studio, Ch?teau Blanco, and in various spaces in the Philly area. http://jeffwhiteaudio.com/

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jv
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Joined: Thu Jan 27, 2005 5:00 pm
Location: Seattle, WA

Post by jv » Tue Mar 04, 2008 10:33 am

ipressrecord wrote:I bought one for $12 in 2004 (I think that exact model) and it sounds decent, however it is noisy. Hum in the output makes it unusable for me. Is this a simple cap job, or were these thing noisy to begin with?

Jeff
When I first got this, I tried to test it by putting it in my guitar signal path, and the noise (buzz, hum, etc...) was horrible. I then tried it between the output of my daw and power amp and it was WAY quieter, probably as quiet as any spring reverb can be expected to be. The hum was completely gone. So I suspect maybe it is sensitive to impedence, grounding or ?...
They were designed to be used in "hi-fi" systems so I would expect them to be fairly quiet.

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