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Old 13th October 2016, 12:43 AM
bikerhifinut bikerhifinut is offline
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Default Phono stage incorporated into a preamp and CF out.

Ok gents.
I'm looking at a collection of parts and wondering how best to string them together.
I was thinking along the following lines:
I can build a RIAA phono stage, but instead of using the CF output into the Volume pot and thence into another CF and out to the world, could I feed the output from the phono stage into the volume pot and use the CF output for all inputs via the selector switch?
I think it's probably not a good idea due to the final EQ network being between the output and CF of the phono stage?
It's just a thread I was working on, and reading Bobs idea of a CF-vol pot-CF stage turned the lightbulb on.
So I think I'll follow the path of leaving the Phono stage unadulterated and feed it into the transformer output stage, assuming I can work out a way to fit all of it into the case I have. I was going to fit the PSU in the preamp case but have decided against this as I feel having the PSU away from the signal electronics has all the advantages. I can't see any real disadvantage in incorporating the phono stage with the line stage in one case, for starters there's one less interconnect and associated plugs and sockets.

A.
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Old 13th October 2016, 05:35 PM
bob orbell bob orbell is online now
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Default Re: Phono stage incorporated into a preamp and CF out.

Morgan Jones book, page 540, 3180us, 318us eq. and the problem of interaction, may help you Andy, regarding the use or not of a CF. His phono stage uses 75us first, followed by 3180 and 318us, WD uses 3180 318 followed by 75 along with 3.18. I hope this is of some help to you. BOB
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Old 13th October 2016, 05:44 PM
bikerhifinut bikerhifinut is offline
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Default Re: Phono stage incorporated into a preamp and CF out.

Quote:
Originally Posted by bob orbell View Post
Morgan Jones book, page 540, 3180us, 318us eq. and the problem of interaction, may help you Andy, regarding the use or not of a CF. His phono stage uses 75us first, followed by 3180 and 318us, WD uses 3180 318 followed by 75 along with 3.18. I hope this is of some help to you. BOB
That's pretty much the way I was thinking bob, there's an EQ network in front of the CF which suggests to me that it has to be left "as is" so that all the EQ is buffered from the variable input resistance seen when any sort of potential divider is used. Plus it will be quite a high resistance coming off the anode of an ECC83 which would pose an issue. I'll leave well alone.

Andy.

Last edited by bikerhifinut; 13th October 2016 at 05:44 PM. Reason: dyslexic computer!
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