Seduction hum (how much is normal?)

[denti alligator]

No, ground wire is from the Seduction to the TTPS. And that's where my body adds something to reduce buzz to zero.

I'm not sure I follow, is the wire secure on both ends but your touching it makes the buzz go away?

The wire is secure at the Seduction end. When I attach the alligator clip to the screw at the back of the TTPS buzzing is significantly reduced, but not entirely eliminated. Only when I take that alligator clip in hand and put my other hand on the TTPS does the buzzing disappear entirely. Alternately, if I hold the alligator clip against the back of the TTPS with my hand (so that my hand too touches the unit) the buzzing also stops entirely.

Note, buzzing is *significantly* reduced by just attaching the ground wire with the alligator clip. The addition of my body reduces buzzing down to zero.

[Doc B.]

Yeah, this is the kind of thing I have experienced. My hunch is that your skin might be acting more as a capacitor than a resistor and somehow it is shunting off noise that's carried on the wire. As an experiment see if touching the wire at the Seduction end to the screw next to the IEC power inlet rather than the Seduction ground post gives any improvement.

[Grainger49]

How about a ceramic capacitor, 0.1uF, in series with the ground wire?

[denti alligator]

How about a ceramic capacitor, 0.1uF, in series with the ground wire?

I tried one of the Teflon caps 0.1uF and it made no difference. Neither did moving the ground closer to the ground nut on the Sed.

Any other ideas?

[fullheadofnothing]

Reading through this, I have a couple thoughts. Maybe not good thoughts, but thoughts...

First, is the power supply for this table the kind of thing that is "optional"? I.E. you could plug the table into a wall outlet, but instead you plug it into a box that plugs into the wall? If so, have you tried eliminating the power supply? I know it's a pain to change speeds by moving the belt, but maybe it's worth looking into. If you can clear this, it could point to the culprit  being either the power supply or its wall wart.

Also, I don't think anyone has talked about interconnects. Are you using shielded interconnects? How are the shields connected? At both ends or one end. On interconnects with arrows, the arrow points away from the side that has the shield attached. I know in my system, I get less hum if all arrows on my interconnects point away from my Seduction (the shield is attached to the Seduction going to both the Foreplay and the step up, and then all other inputs and outputs point away from the FP).

Hope this helps,
Josh

[denti alligator]

Power supply is not optional, due to this specific design of the P3-24.

I'm using cheap interconnects, so this could be the problem, but I doubt it. Any recommendations on fairly inexpensive but quality shielded interconnects?

[matthewmckay]

The shielding may be over-kill... but I love my interconnects from   'the-music-cable.com' .  They are very stiff cables, completely shielded in perforated copper, and should be bent into their correct positions before installation.

[fullheadofnothing]

For a cheap option, you could go to your local electronics supplier (Radio Shack or whatever), pick up a spool of shielded twisted pair and some cheap RCAs. Make a couple pairs, one pair with the shield only connected on one side and one with both sides connected. Try both and try the single sided in both orientations. From there, either you're happy with the sound or you can look at commercial designs or DIY recipes using a similar shielding strategy.

[Grainger49]

I think Joshua has hit on something. 

I tried several shielded and unshielded interconnects from my TT to my Seduction.  I got hum with all unshielded interconnects.  If the shield is not solidly grounded on the RCA plugs and/or the common is loose somewhere you can get horrible noise, hum, buzz etc.

Sam,

I thought that with the TT disconnected and shorting plugs in you still had hum.  Have you fixed that?

[denti alligator]

I'm calling what I hear when the TT is unplugged and the Sed shorted tube rush, not hum. The hum seems to be down to a minimum when I place the Sed on the floor. Right now I'm still trying to get the TTPS grounded well enough to eliminate all the buzz.

I don't think the interconnects are the problem here. Though I'm willing to try that at some point.

I'd like to be able to get the same silence I get when I hold the grounding wire with one hand and touch the PS with the other. Should I try another capacitor? A resistor, maybe? How is my body making the difference?

[Paul Joppa]

I think there is a confusion with words. When you say "the TT is unplugged" are you referring to the power supply unplugged from the wall outlet, or the cartridge interconnect unplugged from the turntable, or the cartridge interconnect unplugged from the Seduction?

What led me to this question is a desire to better guess whether the buzz is electric fields (wire or body acting as an antenna, typically for radio-frequency fields) or ground wire currents.

This has become a long thread, and it's difficult to get all the data together to make sense of it. Perhaps we should first concentrate on the buzz, ignoring the hum and the tube rush until the buzz problem is solved. Can you summarize the exact configuration or configurations which have teh buzz, and the one that does not?

[denti alligator]

By unplugged, I primarily mean not plugged into the Seduction.

But if we focus on the buzz, that's not an issue. The buzz comes when everything is plugged in as if I would put on a record.

Only when I hold a ground wire attached to the Seduction in one hand and hold the other hand to the PS does the buzz stop. If I attach the wire to the PS without going through me the buzz is significantly reduced, but not entirely.

[Grainger49]

  .  .  .   Only when I hold a ground wire attached to the Seduction in one hand and hold the other hand to the PS does the buzz stop.  .  .  .  

This would be an inconvenient listening position to me.  I would have to run wires from the TTPS and Seduction about 16 feet to me and back.   I can see why you don't want to do this.  That is all tongue in cheek.  I got the picture of that in my mind and had to say it.  I had an uncle who watched his TV with his big toe on the tuning knob to keep the picture straight.  (The tuner needed cleaning)

Sam, the problem is that this is a very odd situation.  Usually hard grounding works.  I'm pretty much out of steam here but I'll continue to follow the thread and contribute when I think I have some value to add.

[fullheadofnothing]

I think it has been well covered here that hum problems are complicated, and sometimes the fix doesn't make sense and/or isn't really fixing the problem, but moving it around. My point is you have to be willing to try anything, because everyone posting in this thread has dealt with this stuff and there is no panacea.

Things suggested and never tried:

[denti alligator]

Been very busy, and haven't been able to troubleshoot this as much as I'd like. But I am very grateful for everyone's input!

Right onow i'mwilling to live with the very slight hum. And with the ground in place the buzzing is really only audible at 90 or higher on the volume. I don't use that often.

I briefly experimented with the ground again, this time putting an alligator clip and wire at the PSU and the other at the Seduction, and indeed the buzz completely goes away when I connect those wire with my hands.

There was speculation about my body acting as either a resistor or capacitor. Putting a .1uf cap in the chain did nothing. Any suggestions for what else I might put in the ground to replicate the effect of my body?