Background noise

Swampwalker, actually there is no loading mismatch, but I think your diagnosis is correct -- noisy tube, exacerbated by being below the minimum input voltage.

I'll look into it and let you know. Thanks.

I agree with Swampwalker.

First, a MC cart is not intended to be used in a MM phono circuit.

Second, if the minimum is cartridge output for the phono section is 3mV, and if your cart outputs 2.5mV, then there is definitely a mismatch which will be exacerbated by the phono circuit's amplification.

I'd suggest trying a MM cart, even an inexpensive one, to hear what improvement in the background noise might be gained.

Tvad sez, "First of all a MC cartridge is not intended to be used in a MM phono circuit"

To pick a nit....there is no difference between an MM and an MC circuit except for its ability to respond to the loading and gain demands of the cartridge. There are MC cartridges that are high gain and load at 47K (or up to). A flexible phono stage with adequate gain can handle both types of cartridges (my SP10 does it quite well). But as with Ggavetti, using my .9v output Benz produces tube hiss when you run up the volume to LOUD. It is basically noise free with high output cartridges, MC or MM. Low output cartridges need not apply.

BTW, while tube selection is critical, noise free tubes will not overcome tube rush caused by inadequate gain.

At least I think so this morning. :-)

I stand corrected about MM and MC phonos.

I still believe a gain mismatch is contributing to the OP's noise issue.

"I still believe a gain mismatch is contributing to the OP)'s noise issue"

As you should, you are correct! In fact it is central to the issue. IMHO of course.