Seduction hum, buzz and sound quality issues

[vetmed]

"Butchering cables is a little harder, since they are designed to be thrown away rather than re-soldered"

With clip leads soldering is unnecessary, and if you have gotten this far without wire cutters and wire strippers you must be exceptionally talented Seriously, you do have some clip leads, don't you? Indispensable for measuring high voltages since it leaves one hand free And if you want to simulate a load all you need is a resistor of the desired value.

Robert Lees

[rebbi]

Okay, I finally got me two of these guys, on eBay, all the way from Hong Kong.      It also comes with a screw on collar piece.

Now, I solder the center pin to the other tab, yes?

[Grainger49]

For crying out loud!  You can get shorting plugs at Radio Shack, I did.  It needs not be fancy.  Just a plug that can have a dummy load or a dead short on it.  I have labeled mine so I don't short an output from a source.

[rebbi]

Okay!

I have finally done my shorting plug tests. Time for all of your expertise.

With the shorting plugs on the inputs of the Seduction, I get a rather loud "whooshing" noise in both channels, that oddly seems to be somewhat louder in the right channel than the left.

With the Seduction connected to the turntable, it's the same as before; nasty hum/buzz in both channels that gets buzzier when the table motor is turned on. The noise gets louder when I touch the tonearm and softer when I touch the plinth. By the way, I have tried different preamp inputs just to make sure it's not the preamp itself, and it's not; the noise follows the Seduction.

Ideas?

[Paul Birkeland]

A wooshing sound is tube rush, which is generally a normal operating condition.  I'm guessing that the hum went away when you inserted the shoring plugs?

We never did hear which arm you have on your turntable.  Often times Sota turntables ship with Rega arms, can you confirm?

[fullheadofnothing]

The Ortofon 2M series of cartridges have a metal screw on top that is there to ground the cartridge to the arm. In practice, this causes more problems than it solves. You can try not using the arm's ground wire, which might eliminate the ground loop.  If that doesn't solve the issue, you can put an insulator between the top of the cartridge and the arm, or replace the cartridge. Both of these will require the skills to mount a cartridge.

Wooshing sound is probably tube rush. Are you testing at higher than normal listening levels? If not, try another set of tubes.

[rebbi]

A wooshing sound is tube rush, which is generally a normal operating condition.  I'm guessing that the hum went away when you inserted the shoring plugs?

We never did hear which arm you have on your turntable.  Often times Sota turntables ship with Rega arms, can you confirm?

Yes, the hum went away with the shorting plugs.

The arm is a Linn Basik LVX, which I bought with my first good 'table (a Systemdek) in the mid-1980's and later moved to the SOTA when I bought it.

[rebbi]

The Ortofon 2M series of cartridges have a metal screw on top that is there to ground the cartridge to the arm. In practice, this causes more problems than it solves. You can try not using the arm's ground wire, which might eliminate the ground loop.  If that doesn't solve the issue, you can put an insulator between the top of the cartridge and the arm, or replace the cartridge. Both of these will require the skills to mount a cartridge.

Wooshing sound is probably tube rush. Are you testing at higher than normal listening levels? If not, try another set of tubes.

Yes, the "whoosh" is with the volume turned up pretty high; I don't hear it normally at all, and it's only with the shorting plugs on the Seduction.

Removing the TT ground wire spade from the Seduction ground screw doesn't affect the hum.

Through the headshell, I think I can see the hole in the top of the Ortofon cartridge that must be intended to receive the grounding screw you mentioned. The SOTA factory mounted the cartridge for me when I sent the TT back to the factory for a refurb a couple of years ago. It seems they didn't use the ground screw, just the two mounting screws on top.

I can also double confirm that it's not the Seduction because a local dealer was nice enough to lend me a cheap little NAD PP 2 phono pre for testing, and the hum's still there with the NAD installed.

[fullheadofnothing]

The screw is there to make a physical conmection with the bottom side of the headshell; it should be nearly invisible when the cartridge is mounted. If you are capable of re-installing the cartridge, remove it from the headshell, but leave the wires attached. Check for hum, my guess is it will be gone. If you cannot carry out this experiment, find someone who can.

[rebbi]

Well, I tried something similar. My local dealer loaned me a few old cartridges, and suggested I remove the lead wires from the pins on the mounted Ortofon and then attach them to one of the loaners and see what happens, to determine if the hum is from the Ortofon having bit the dust. I did this with two of the loaner cartridges and in both cases the hum/buzz was still there. So it's something else.

I'm kind of stumped at this point. I think I'll try to borrow a turntable from a DJ friend of mine and see if the substitute table also has the hum...

[Paul Birkeland]

Can you confirm which tonearm you have?

[rebbi]

Can you confirm which tonearm you have?

Linn Basik LVX

[Paul Birkeland]

Hmm, can you let us know what the second grounding wire is connected to?  (See the link)

Linn Arm Issues

[Grainger49]

   .  .  .    With the shorting plugs on the inputs of the Seduction, I get a rather loud "whooshing" noise in both channels,  . . . .   

So we are saying that the shorting plugs remove the ugly hum/buzz.  That says it is a problem with the table arm combination not the Seduction.  Or at least an interaction between the grounding schemes of the table and arm with the Seduction.  The Seduction alone, inputs shorted is quiet.

It is sad when good tables have a bad interaction with a phono stage, but this happens and it is a ground loop somewhere in the table.  I blame it on the non-standard grounding practices since the 50s.

As others have mentioned the "whooshing" noise could be the tubes.  Give them a four day run without anything else turned on and see if it goes away.

[rebbi]

Hmm, can you let us know what the second grounding wire is connected to?  (See the link)

Linn Arm Issues

Paul,
Thanks for the link. The SOTA Sapphire is a heavy beast to move but I will carefully wrangle it and try to see what's going on underneath the table and whether my Linn arm has the "extra" lead. I also want to give a shout out to my local brick and mortar stereo shop, Audio Systems in Austin, TX. They've been great about lending me stuff to help me try to sort this out. Good folks.