Protecting my speakers et al from Turntable static pop

dvb · « **on:** 23 May 2004, 03:40 am »

My Spacedeck Turntable seems determined to double as a Van de Graf generator -- records that go on with no static come off with a wicked static charge. This has also been reported by others on vinyl asylum. Efforts to ground it or otherwise control static with humidifiers etc. do not work (I haven't tried the humidifier, but this happens on the rainiest of days on the "Wet Coast". ) While I would love to deal with this at the source, this so far has not been an option.

With previous preamps (Bryston B60, FT-LW1 passive), I could control the problem by just "parking" the input selector in the adjacent "non phono" input position, and no pop came through the speakers.

This doesn't seem to work with the T7SL with built in phono. I have tried switching to adjacent position, switching from "input" to "tape", turning the volume all the way down, all these together, and all permutations thereof, to no avail.

Any suggestions?

TIA

dvb · « **Reply #1 on:** 23 May 2004, 04:29 pm »

Is the different experience with the T7 because the phono stage is built in?
With the other preamps, I was using an outboard tubed phono stage (WPP100C) -- perhaps that was therefore more isolated from the preamp when I was able to change the selector from that outboard in to another unused "in"

There is certainly no signal from the stylus when I have the selector/tape/volume controls made.

The static charge does not seem to travelling any path other than the air.

I am trying to solve this at the source by inquiries at Vinyl Asylum -- I'll probably also fax Tom Fletcher at Nottingham Analogue -- this is a common, but not universal, problem (I wonder if the people with the problem are using tube phono stages -- are tubes likely to pick up this charge and amplify it?)

It is has been suggested that I run a grounding wire from the bearing sump to the same grounding point on the preamp that the tone arm ground goes to.

Or, that I accept that the TT is going to generate this charge, and drain it through myself when I pick up the record by grounding myself to the amp.

Any potentially "hair raising experiences" here?

avahifi · « **Reply #2 on:** 23 May 2004, 06:01 pm »

This the first concern we have ever heard about regarding use of one of our preamps with a turntable/cartrdgie combo that caused a pop even if the preamp was switched to a different input and volume down. Can you describe the problem in more exact detail for us? I am wondering if there is a DC voltage on the interconnect cable from the turntable to the preamp. There should not be.

Frank Van Alstine

dvb · « **Reply #3 on:** 24 May 2004, 04:47 pm »

Thanks, Frank, for climbing on board with this problem. I do not know a great deal about electronics, but I hope the following provides the detail you require.

1) The problem:

I put a clean, no-static LP on the turntable (TT), spin one side, and as I lift the record from the TT, I get big pops through my speakers.

I think it is clear that the problem originates with the TT, but I have not been able to get that solved yet. In the past, with a separate phono pre into a pre-amp, I have been able to at least keep the popping from coming through the speakers by “parking” the input selector in an unused source option.

This has not worked since I started using the phono stage in the T7SL; neither has turning the volume down or switching from “Input” to “Tape” .

2) The turntable and pick-up:

I think it is clear that the problem originates with the Nottingham Analogue Spacedeck Turntable. According to discussions on Vinyl Asylum, this is a fairly common problem with Spacedecks, but not everyone has it.

As you may be aware, the Spacedeck is an open design with no chassis -- the spinning part of the TT just sits on its three rubber-tipped feet on any surface (an MDF-type slab is provided). Here’s a link to a picture: http://www.aslgroup.com/nottingham/index.htm

The spindle is isolated to the TT and is directly connected to the shaft that rests on the bearing in its oil sump beneath the TT. The AC motor is in a separate pod, connected to the table only by the round rubber drive belt. The power cord is a three- pronged plug.

The tonearm is also in a separate pod from the TT, connected by a bolt to the fixed portion of the TT under the revolving portion. The pod rests on a single rubber foot.

The tonearm is an Origin Live modified Rega RB250 tonearm, with the Incognito rewiring kit that I installed. It has a separate grounding wire, unlike the stock Rega. The arm was not a problem on my previous TT, a Systemdek IIX (but using a SS phono pre). Cartridge is a DV20XH.

Spacedeck owners using the Spacedeck arm also report the problem.

Some have suggested using a humidifier, but I don't think the problem comes from the environment -- I live in rainy North West coast city, and it happens in all weather. I’ve just had an e-mail from a local fellow who says he does not have this problem. I have tried various TT mats, anti-static spray on the carpet, and even anti-static spray on a TT mat, to no avail.

An archive search indicates attempts to ground table don't help, but I am prepared to try this, as the suggestion that static is being generated by the bearing makes some sense. I would propose also connecting a ground from the bearing shaft housing under the TT to the phono back of the T7, where the tonearm is grounded.

3) Amplification

I bought the T7SL about a month ago from your customer, George Hoenninger. (George was great to deal with and provided great service.) George had added Mullard tubes in the line stage and Cromalloy strips to the inside top of the case (these are two “Band aid” length strips of material that I believe are intended to damp vibration – they must be irrelevant to this discussion).

The T7 is connected to the (used) 500ex amp I bought from you a few months ago. It is connected by Bogdan Silver Spirit Reference interconnects.

The tonearm is connected by its RCA plugs to the Special input on the T7, and the ground wire is attached by its alligator clip to the phono grounding screw on the back of the T7. Only other component attached into the CD input, a Bolder Mensa modified ART DIO DAC.

My gear (including the amp) is plugged into a Monster HTS2000 bar. There is a light on the Monster that indicates the ground is effective (generally, I have plugged the amp directly into the wall, but have plugged it into the Monster for now to keep the grounds consistent). I have tried plugging the directly TT into the wall with no effect.

4) Experience through the T7SL

Prior to the I was using the George Wright WPP100C phono stage. This had been input first to a Bryston B60 and then to an FT-LW1 “Little Wonder” passive. The popping was experienced with both of these, but could be isolated from the speakers by parking the input selector in a non-phono input.

Attaching the WPP100C to the T7 through the Tuner input, I cannot isolate the popping by parking the input in Spare, by switching from Input to Tape or by turning the volume down.

Likewise, attaching the tonearm directly to the T7 through the Special, I get the popping through the speakers no matter where I park the input selector, whether I switch to the Tape input, whether I have the volume turned completely down, or whether I use all three.

My thanks again for your help with this problem.

JoshK · « **Reply #4 on:** 24 May 2004, 05:14 pm »

sounds like the input selector doesn't switch ground. I get some static build up with my open chassis TT as well, although never quite a loud pop. My source selector switches ground as well so I never get it when the TT is not selected.

Grounding the bearing is a good idea. If ground to the phono doesn't work, try grounding to the amp. Regardless I would imagine you need to ground the bearing to the same ground as your cartridge to avoid potential. FVA can probably add a great deal more than I can, but just wanted to say I have experienced some of this to a lesser degree (different preamp).

dvb · « **Reply #5 on:** 24 May 2004, 06:22 pm »

Interesting that you are also using a Rega arm with Incognito wiring and DV20XH cartridge.

I very nearly went with the Teres turntable, but did have the "shop" space in my home to do the DIY finishing and assembly that was then required.

JoshK · « **Reply #6 on:** 24 May 2004, 06:39 pm »

yes I noticed the coincidence as well. Very good, for the money and just in general, IMO.

avahifi · « **Reply #7 on:** 24 May 2004, 11:32 pm »

First thing I would suggest you try is a 3 to 2 cheater plug on your ac power cord for the turntable motor (eliminating the chassis ground at that point). Next I would suggest measuring the DC voltage on both the ground and hot side of the phono cables (unplugged from the preamp) both with the turntable motor on and off (should be zero in all cases). Next make sure your tonearm wires are not making and breaking continuity as you lift the arm.

Note that all of our preamplifiers do switch ground sides (all unused inputs are grounded except for the tape inputs) to eliminate crosstalk.

I am guessing you are building up a big electrostatic charge on the turntable that you are discharging when you lift the arm. I assume you are lifting it by hand, not with a cueing control or am I wrong? You are discharging this when you touch the arm and the voltage discharge is bleeding thru the ground side or AC side in spite of our best efforts to prevent this.

Frank Van Alstine

dvb · « **Reply #8 on:** 25 May 2004, 01:48 am »

Thanks for the suggestions.

In fact, I lift the tone arm with a cuing device, not by hand. There is no audible "event" that accompanies removal of the tone arm.

The pops come as the vinyl LP is separated from the turntable. They can continue as the LP is removed as far as 2 feet from the Turntable (Lifting straight up about 2 feet works best -- but a bit of a silly dance!)

Tomorrow will be a trip to Home Depot depot and Radio. I'm not sure they will sell me a cheater plug -- last time the local hardward store said they were against code.

Would plugging the TT into the back of the Preamp, rather than into the Monster help? (of course, two prong cheater required for that)

I'll also pick up the necessary meter to conduct the tests you suggest, as well as to check the bearing sump, and a ground fault tester. I'll also pick up an alligator clip for a wire to ground the bearing sump.

Hey Ho!!

(Barbeque Marinated Rack of Lamb, fresh large asperagus and tomatoes and a full Merlot now require a walk in the just cool summer evening. The stereo now falls silent!)

Tonto Yoder · « **Reply #9 on:** 25 May 2004, 10:52 am »

Quote from: dvb

Thanks for the suggestions.

In fact, I lift the tone arm with a cuing device, not by hand. There is no audible "event" that accompanies removal of the tone arm.

The pops come as the vinyl LP is separated from the turntable.

Yep, that's the crackle-pop-crackle song of the Spacedeck! Sounds almost identical to my Rega armed Space--as if the static now on the LP jumps over to the stylus as the LP passes by as I either return the LP to its jacket or flip it over. Fortunately, my preamp has a mute switch that keeps the crackle-pop-crackle silent.

BTW, Radio Shack has the cheater plugs--
http://www.radioshack.com/product.asp?catalog%5Fname=CTLG&category%5Fname=CTLG%5F009%5F001%5F003%5F000&product%5Fid=61%2D2720

dvb · « **Reply #10 on:** 25 May 2004, 01:34 pm »

When I try the various muting options on the AVA T7, (parking in adjacent selector, tape in, no volume) there is no sound through the speakers when I, for example, brush the stylus (admittedly a soft sound).

So, the AVA mutes do seem to be working at some level. It makes me wonder if the static is finding its way into the system by some means other than the cartridge -- I know next to nothing about electrictity, but it seems more as if this is discharging between the record and the platter and into the air,and getting picked up by the preamp that way -- kind of mini lightening strike!

avahifi · « **Reply #11 on:** 25 May 2004, 09:15 pm »

I am thinking the electrostatic discharge is finding its way in thru the ground side of a connection due to some bizzare grounding arrangement wiht the turntable. Note that all of the inputs on our preamps are shorted to ground when not in use (except tape inputs) and the volume control goes to full off so I doubt if the discharge snap is getting in on a signal cable. I am suspecious of some significant dc leakage somewhere from the turntable. Since others have noticed the same problem with that turntable model you should examine that first.

Frank Van Alstine

dvb · « **Reply #12 on:** 26 May 2004, 05:41 am »

Preliminary tests are promising (and probably conclusive):

I began with the following (very sophisticated

) testing apparatus:

1) A piece of fairly stiff single strand wire -- I wrapped one end around a hot water heating pipe; I taped a pencil to the other end about 3" back from the other bare end to make a probe

2) A piece of styrofoam packing peanut.

I used the peanut to ensure there was no static on the record.

1) After playing side 1, turned the volume to zero, touched the probe to the spindle, and removed the LP. No pop. LP still quite staticky, according to peanut.
2) I Zerostatted the LP until it passed the peanut test. After playing Side 2. turned the volume to zero, touched the probe to the bearing sump housing under the TT (a steadier hand required to do it cleanly) A barely discernable pop.

3) Repeated test 2 with fresh LP -- volume zero, touched bearing housing -- no pop discernable.

4) Going for broke -- almost bedtime -- put the still staticky record from test 3 on the TT -- played the side (no static on playback), kept volume at two notches above zero, touched bearing housing, removed the LP -- No discernable pop.

So, I am sufficiently persuaded that the bearing turning is generating the charge that my next stage will be to try to (elegantly) attach a ground wire to the exposed bearing housing and run it to the same ground on the back of the T7 that the tonarm is grounded to.

I think this will provide an acceptable solution, even if I have to turn the volume to zero (I would always mute while changing sides anyway)

Thanks to all for your generosity and patience helping this electrical newbie to solve this vexing problem. Special thanks to Frank for standing by his customer (and it's not even his turntable!).

PS

This does not solve all the problems raised by this issue, such as why some Spacedeck owners have this problem and some don't. A fellow at work wondered if it is the nature of the oil supplied for use in the sump. Perhaps the grade is insufficient as a lubricant or perhaps it is more prone to charging. Since everything else is so isolated, that may be worth pursuing.

dvb · « **Reply #13 on:** 30 May 2004, 01:41 am »

Just as a follow-up, I have implemented grounding the bearing sump to the phono grounding post of the T7 preamp. In fact, the ground from the sump is wrapped around the post, and the alligator clip from the tonearm ground is clipped to that ground to hold it on.

This, I understand, would be a "star grounding". It is actually working better than grounding to the hot water heating pipe, which I used in my testing.

There is nothing fancy about the attachment to the sump. The sump is a 1.5 cm long and 1.5 cm diameter metal post protruding from the bottom of the turntable. I simply stripped about 3.0 cm from a small, multi-strand, well-insulated copper wire, splayed the wires a bit and looped it over to get good coverage. I secured this to the sump with plastic "ratchet-type" cable tie.

I have since played several records with nary a pop, even with some volume turned up.

So, the source of the static build-up may remain unclear -- bearing turning, belt engaging/disengaging while spinning, tonearm wiring, have all been suggested -- but grounding the sump to the preamp phono ground solves the problem beautifully.

Thanks to all for your contributions

dvb · « **Reply #14 on:** 31 May 2004, 05:22 am »

The fix was implemented on Saturday.

As I listen more extensively on Sunday, it is still working beautifully, but I should mention that there is still a lot of static being generated -- LPs come off with a lot of charge on them -- it's just that the charge is no longer finding its way into the sytem.

What a relief that is, not to have to cringe every time I take a record off.

I have also felt sufficiently comfortable to install the NOS Tungrams in the phono stage, as recommended by Zybar and Kevin. Very nice -- lots of detail, but very smooth. A worthwhile upgrade from the EH and JJs (although those were very listenable also).