Bottlehead Forum

General Category => General Discussion => Topic started by: Downhome Upstate on June 19, 2014, 09:31:07 AM

Title: MM cart, SS phono stage, and Hum
Post by: Downhome Upstate on June 19, 2014, 09:31:07 AM: Hi folks. Long time; no post. Good to be back.

I went off the reservation ::) and think I goofed.

I had a Seduction w/C4S and homebrew Cinemag 3440A SUT; I was using them with a Denon 103-R, and really liked the sound. But, you know how it goes, I sold them and bought a shiny new Musical Surroundings Nova II phono amp. Solid state, highly configurable, battery powered. Then I saw a NIB Clearaudio Virtuoso Wood (v.1) MM cart, and thought 'Hey, I'll bet this would sound great with the Nova II !'

So I bought the cartridge at a good price and fitted it to the 'table. It puts out about 3.6 mv. (The specs call for 100 pf loading, but the Nova only has selections for 200 or 300 pf. I have 200 dialed-in) Now, with 40 - 46 db gain from the phono stage there's significant hum with the Stereomour volume pot at 12 o'clock. What to do (besides selling the Nova and buying an Eros kit)?
Title: Re: MM cart, SS phono stage, and Hum
Post by: roscoe primrose on June 19, 2014, 09:39:01 AM: The impedances involve with your MM cartridge are a couple orders of magnitude higher than they were with your MC cart, which makes pickup of stray electrical noise much more likely. Double-check your grounding, and cable/component layout...

Does it hum w/o the cables plugged into the Nova's inputs?

Roscoe
Title: Re: MM cart, SS phono stage, and Hum
Post by: Paul Birkeland on June 19, 2014, 02:05:03 PM: Did you ever try the old cartridge/SUT combo with your new phono preamp?

I don't know what 12 O'clock means. If you listen to music at that level, does smoke come out of your speakers?
Title: Re: MM cart, SS phono stage, and Hum
Post by: Downhome Upstate on June 19, 2014, 11:53:08 PM: Quote from: Caucasian Blackplate on June 19, 2014, 02:05:03 PM
Did you ever try the old cartridge/SUT combo with your new phono preamp?

I don't know what 12 O'clock means. If you listen to music at that level, does smoke come out of your speakers?

No smoke, PB. I just got a few Classic Records Blue Note mono reissues, and the SPL w/the volume cranked to halfway is moderate, but not loud. I have a small listening room, and I listen nearfield (about 6' away through a pair of Orca's w/a small REL sub). I'm 60 and I probably have some hearing loss, but not too much (other than what happens in front of a PA speaker stack at a Johnny Winter concert a million years ago).

Anyway, what's your point?
Title: Re: MM cart, SS phono stage, and Hum
Post by: Downhome Upstate on June 20, 2014, 02:14:39 PM: Not surprisingly, its a ground loop issue. All better.
Title: 100pf is the capacitance of your cables
Post by: richardl on June 27, 2014, 11:56:29 AM: If you have a cart with 100pf loading, you unload it by adding neither 200 or 300pf. You are good to go.