Seduction hum, buzz and sound quality issues

[Grainger49]

Hum/buzz is a hard problem to find.  Sometimes inverting the power plug on one device cures it.  Did you try shorting plugs, the above post includes a link?

 

[saildoctor]

Do you know how shielded your interconnects are?  I was getting a lot of hum from my VPI Classic > Seduction > FPIII with some ICs that had foil shields. I made some diy ones with a heavier braided shield that seem to help quiet down whatever I'm picking up.

 

[Paul Birkeland]

I'll just mention here that 3 years ago, there was a first step recommended to sort this problem out.  It involves going to a Radio Shack and spending about $10, or placing a parts order online for about the same amount. 

I would start by following through on that advice, then we will actually have the information we need to help you sort this out.

 

[rebbi]

Okay, I looked on eBay for RCA shorting caps and found a guy selling gold-plated brass ones for about $13 for a four-pack, plus shipping from Hong Kong, which seems ridiculous. So I'm gong to sacrifice two of these plugs (as in the photo) and solder the stripped end of the wire to the outside of the round, metal collar on the plug. That's all I need to do, right? (Sorry for being cautious/dense.)

 

[vetmed]

Go to Radio Shack or your local discount electronics store. Buy a crappy quality RCA to RCA cable. Amputate one plug, strip the insulation. 2 conductors which you can now short using clip leads.

Robert Lees

 

[fullheadofnothing]

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

Plugs:
http://www.radioshack.com/product/index.jsp?productId=2103423&retainProdsInSession=1
4 pack, $3.49 ($0.87 each)
Every RadioShack has these in stock. Ask for part number 274-319 if you can't find them.

http://www.ebay.com/itm/RCA-Plug-Solder-Type-Audio-Cable-Connector-device-Intelligent-info-/300861665368?pt=LH_DefaultDomain_2&var=&hash=item460cc0b058

$0.94, free shipping, get at least two.

 

[rebbi]

Golly, the customer reviews on those Radio Shack plugs are the angriest I've ever seen (as in "this is the cheapest crap I've ever seen") but I guess for my purposes they'd be fine, eh?

 

[howardnair]

rebbi!-the problem seems to be from your turntable-i won't say that is for certain-but the buzzing changes when you touch that component--  make sure that your ground wire for your turntable is not broken inside the insulation or rt at the terminal  and then have a look at the wires in your headshell

 

[rebbi]

Howard,

These are good suggestions. The headshell wires look okay; nothing seems to be loose or anything. As for the tonearm cable, what you suggest about a short in the ground wire isn't impossible. The arm (a Linn Basik that I bought, used, in the mid-1980's!) is still using the original cable, so maybe it's gone bad...

 

[howardnair]

well i wouldn't say the cable  has gone bad -take a ohm meter and connect to the end of the ground wire and the other to the base of the arm you should get some continuity-that is usually the general vicinity of the other end of the ground wire-i am not sure about cking the continuity further up at the headshell -i know you should not put the meter on a  cartridge -

 

[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.  ;D  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...