Phono Stage Hum

The gain was high for MM cartridges. I talked to the Jolida dealer, and he said that they typically recommend no gain for MM cartridges. I'm not sure what you mean by the riaa equalization in the path.

The hum is roughly equal in both channels and they are all plugged into a Shunyata Guardian.

I have had a small fear that there is a bit of crowding around the cabling. That is part of what I will experiment with this weekend.

I do get the hum when the turntable is not turning. I also occasionally get a pop when I turn it on... Something I just remembered.

Good advice on the shorting plug. That might be my first test.

Thanks,

tim

Check all connections including those to the cartridge first.

If still a problem, check proximity of the phono stage to other components and any other devices emitting magnetic fields. The power amp is a prime suspect. Move it around physically and see if hum increases/decreases. Try to locate it where hum is minimized or hopefully gone.

If that is it, I have been treating a similar issue with my phono. Check my system postings for more info on solutions involving adding additional magnetic shielding, if needed.

I'm totally confused by what the dealer told you. As I indicated, 70db phono stage gain for your 4mv cartridge does seem a bit excessive. But "no gain" is absurdly too low -- that would say that on loud passages only about 4mv would be going into your integrated amp -- WAY too low.

Also, how physically was the gain adjusted to 0 or whatever it was set to. Based on the JD9A description at their website it just seems to have 3 settings -- 70, 85 or 95 db.

Re RIAA equalization, as you may know records are cut with non-flat frequency response (20 kHz boosted around 20 db; 20 Hz cut around 20 db, relative to 1 kHz, with boosts or cuts for other frequencies corresponding to a specified curve). The phono stage has to apply an inverse frequency response curve, to restore a flat response relative to what was recorded.

The JD9A description at the Jolida site says something about "Two Outputs RIAA, Line stage." Not sure what that means, but it sounds like one pair of outputs might not have the RIAA equalization in the path, for whatever reason. If not, and if that is the output you are connected to, you will not get good sound to put it mildly (although that may be unrelated to your hum problem).

Regards,
-- Al

Might be the nature of the beast. I have the 9A and also have a low level hum. It is not audible unless it is very quiet or I put my ear to the woofers. I have tried all the suggestions mentioned above with no luck. Play with your cartridge settings as I was able to reduce, but not eliminate the hum.

On the Jolida: There is a high output and a low output. Both seem to be line level. I have been running the high output to my integrated. Maybe I will run the low output to the integrated, and then set the gain for the MM cartridges. That might be the best way to start.

In the manual, it says that the "low" is for preamp separates and the "hi" is for integrated amps or line stage preamps. That is why i have been using the high.

I just pulled the phono cable out of the phono pre. I still get some low level hum (actually a noise more like wind blowing across a mic) but I have not put the shorting plug in yet. That strikes me as potentially noise around the tubes.