RIAA preamp kit recommendations?

[zany]

Thanks for the reply ALPUY, that will be my next job - to separate the supply into its own enclosure. I tried some aluminium angle as a shield which helped, but not enough. Pic is of first power up while waiting for enclosed terminal blocks for psu wiring.

 

[ALPUY]

Try separating the two boxes with steel sheeting, not aluminum. I've read somewhere that aluminum isn't useful for isolating electromagnetic interference.

 

[zany]

Thanks, will do. cheers.

 

[ALPUY]

I think there may be a ground loop. There's a ground connection on the input and output connectors, and another ground connection on the transformer's center wire.
Try to clear the latter.

 

[ALPUY]

If you want to flatten the bass boost, replace the 180kohm R4 with a 150kohm one.
It achieves a completely flat frequency response.

 

[zany]

ALPUY, all grounds terminate to the chassis ground as a star ground, then connects to the IEC earth ground. Before this arrangement, hum and buzz was quite loud.

 

[Kevviek]

watching….I have built one but it’s not yet in an enclosure…

 

[ALPUY]

ALPUY, all grounds terminate to the chassis ground as a star ground, then connects to the IEC earth ground. Before this arrangement, hum and buzz was quite loud.

I agree with you regarding star grounding.
What I was saying is that it seems to me that the connection you make from the transformer's center to ground is what's likely causing the ground loop.

 

[sachu888]

https://audiokarma.org/forums/index...igh-end-phono-stage-no-expense-spared.371889/

Regards
Sachin

 

[zany]

I agree with you regarding star grounding.
What I was saying is that it seems to me that the connection you make from the transformer's center to ground is what's likely causing the ground loop.

I will disconnect it and report back.