Grounding issue and vinyl care

[sachi]

Had a quick question on ground noise.

I currently have the ground wire from the turntable conencted to the chassis on my preamp.

WHile this reduced the ground noise considerably, its still fairly audible once i go past the 11o clock position and quite annoying when listening to the quieter passages on a track.

I notice that when i touch the tonearm and the power switch on the turntable together, the noise floor drops another significant step which would be acceptable.

Any idea what could be causing this? I am thinking of running a wire from the ground wire on the turntable which should be connected to the tonearm body (correct me if i am wrong) to the body of the power switch.


Someone on audio circle recommended that i re-wire the cartridge, but i doubt if this is the problem. Nonetheless will check it out.

Should i be looking at something else instead?

___________

Next, need to invest in vinyl care. Thinking

1. disc doctor fluid.
2. VPI or disc doctor brush , one for wet and one for dry cleaning.
3. Zerodust stylus cleaner
4. digital jewel scale for tracking force measurement.
5. Lint free cloth. Does chamois work well here?

Anything else i might have missed?

Thanks for any input you guys can provide to a clumsy vinyl noob in advance

 

[sachi]

Well, keeping one finger on the power switch of the turntable and another on the volume knob on my preamp (the ground wire from the turntable is connected to the preamp chassis), there is dead silence.

Disconnecting the turntable GND from the chassis of the preamp induces a lot more audible noise on the other hand.

Never had problems with the preamp in my digital rig and it does have a ground loop breaker in it.

hmmm lol

 

[sachi]

ok.. got the grounding issue sorted out. Just had to run a wire from the turntable ground to the body of the power switch on the turntable. It is very quiet now.

 

[malvai]

Sachi,
what tonearm are you using?

I had a similar hum problem, and it went away the moment I braided the tonearmwire right behind the headshell.

For vinyl care, everything on your list is essential. I'd add a onzow Zero dust stylus cleaner to the list as well.. It is the best stylus cleaner that I have used - ever.

 

[sachi]

Hi Malvai,
its a SME3009 series 2.

And yup, the zerodust is there on that list

I am considering DIY'ing a record cleaning machine down the line using an old turntable

 

[tek]

I found that after switching to a battery powered pre amp, i am getting a dead silent sound from the TT. Before there would be either slight buzzing or high pitch noises coming from it, even after grounding. But now I get a nice black sound

 

[omishra]

I found that after switching to a battery powered pre amp, i am getting a dead silent sound from the TT. Before there would be either slight buzzing or high pitch noises coming from it, even after grounding. But now I get a nice black sound

Tek, if you use good shielded PS (linear regulated with r-core transformer) then it does not get any mains power artifacts into phono preamp. I am using CNC MM phono on PS, never found degradation. Advantage is that I can supply +15, 0, -15 which make signal to PS ratio small, means flat bandwidth.

For not so good PS, buzz, hum and other power line noises are unwelcome guests.

 

[jls001]

Inspired by Sachi's R&D effort, I also tried my hands at mitigating the noise in my system and need further help:

Problem:
a) when turning the speed selector switch (which doubles as the on-off switch), there is a loud pop amplified in the speakers. Highly annoying.
b) when switching on electrical points, same pop is heard. Something somewhere in my audio chain is acting like a fine pickup. Highly annoying.
c) when switching off electrical points, pop is heard but lower in volume. Still annoying.
d) when turning up volume, there is audible noise. This noise is typically audible when my volume is set to -35 dB or higher. My normal listening volume is -45 to -50 dB. When I am in a good mood, this may go up to -40 dB. So during most normal listening situations the noise doesn't make itself felt. Not annoying in normal listening but I suspect this is raising my overall noise floor and reducing the available dynamic range.

What I had done so far (prior to Sachi's post):
a) re-soldered the earthing wire and changed the earthing wire from turntable to phono pre. At turntable end it is soldered. At phono pre end it is screwed down (thumb screw). Result - No change whatsoever except a cosmetically more acceptable grounding wire (bright green cable).
b) I read somewhere that a 0.01 uF capacitor across the supply rail would quieten things down. I tried this but it doesn't help in any way. It still pops like a loud fart.
c) took apart turntable's switch mechanism only to realise that there are no direct electrical contacts within the switch mechanism (TD 124). But one good thing that came out of that exercise was that 33 rpm engages without fail now. Earlier, it engaged when it was in a good mood.
d) extended cartridge ground point to the ground point of turntable. Result - No change whatsoever.

What I did after reading Sachi's post:
a) changed the turntable's power cable from 2-core/2-pin type to 3 pin/3 core type. The earthing point directly soldered to the turntable's earth point (and thus connected to ground lead of cartridge). Still loud pop. Still noise at high volume.

I am now at a loss and need advices and pointers.

For what it's worth:
a) signal cable from turntable to phono pre are double shielded coaxial. Connectors are neutrik RCAs at both ends.
b) Phono pre to pre cables are also shielded. Have tried three different pairs (three different brands). All have the same annoying pop.
c) Pre-amp has floating ground.
d) Power amp is grounded.
e) when turning up volume on CD or PC source, it is quiet even at very high volumes. It is only the analog chain that has noise problem.

With the last change (grounding of turntable) I now have two ground points. Earlier I have checked the neutral to earth voltage of my power supply and it was <2V which I think is quite normal for a domestic environment. Last night I even tried Sachi's trick of touching various points with my bare hands and bare sole touching floor, but it didn't have any effect.

 

[malvai]

^^^
Josh, check where you have placed the phono pre on your rack.

1. Is it near the power amp? if it is, place it as far away as possible.

2. Next check to see if the phono cables are not running alongside/bunched with the power cords.

3. do you hear the noise floor when you play cd? if no then check for the noise floor one by one using each of your TT's...

 

[jls001]

^^^
Josh, check where you have placed the phono pre on your rack.

1. Is it near the power amp? if it is, place it as far away as possible.

2. Next check to see if the phono cables are not running alongside/bunched with the power cords.

3. do you hear the noise floor when you play cd? if no then check for the noise floor one by one using each of your TT's...

Phono pre is now placed to the side of power amp. Earlier it was placed two rack slots above the power amp in its own slot but that has been eaten up by the heavy plinth of TT.

Phono cables are fairly far away from power cables.

When playing CD or from PC, I don't get noise.

 

[sachu888]

Hi Joshua,
Which phono pre are you using?This may be a problem with your phonostage's power supply.You can test this after building HTMCPS and run it on batteries.I feel it will solve this problem.

Regards,
Sachin

 

[Gerry_the_Merry]

Just in case you have connected cable or dish tv to same amp try removing it. I am sure though that a purist like you would not have done it.

 

[jls001]

Which phono pre are you using?

Musical Surroundings' Phonomena.

Added: it is powered by a wallwart adaptor. I think I should seriously check its voltage rating and try running it off battery to see if it is the culprit I have been trying to catch.

 

[jls001]

Just in case you have connected cable or dish tv to same amp try removing it. I am sure though that a purist like you would not have done it.

My cable is plugged directly to TV. No STB. No fancy-schmancy DTH either. TV watching is very, very less.

 

[sachu888]

Musical Surroundings' Phonomena.

Added: it is powered by a wallwart adaptor. I think I should seriously check its voltage rating and try running it off battery to see if it is the culprit I have been trying to catch.

Wallwart is not a good option.Try run it on well filtered Power supply or batteries.It will cure your problem.

Regards,
Sachin

 

[malvai]

Phono pre is now placed to the side of power amp. Earlier it was placed two rack slots above the power amp in its own slot but that has been eaten up by the heavy plinth of TT.

Phono cables are fairly far away from power cables.

When playing CD or from PC, I don't get noise.

keep your phono pre away from the power amp.... it should lower the noise floor considerably...

 

[omishra]

Copied from my another forum post.

With my experience I can see many probable places which can be looked upon.

1. If your mains earth ground is connected to chassis and same time phono's analog ground is also somehow connected to earth ground and chassis then you get this issue.
   Remedy: Connect mains earth ground to chassis but separate audio ground by isolating it from chassis and earth ground. Now put connection like this
   
   
2. If PS does not have good filter to remove ripple then this could happen.
   Remedy: Use C-R-C filter on the output of rectifier with C >=4700uF (voltage rating as per requirement)and R=1ohm,2W (wattage as per requirement).
3. Ground wire from TT arm to phono is not connected to clean ground inside phono.
   Remedy: Internal connection of tonearm ground wire is connected to output of PS DC ground. in above diagram zero volt line refers that.

PS: CFL and proximity of SMPS can add buzz to sound, IMO hum is different.

 

[sachi]

welp..i just got done removing all the crappy chinese caps and cheap ceramic decoupling caps and the NE5532 opamps on the Cambridge 640P.

Should be getting the panasonic FR lytics and murata NPO ceramic caps tomorrow along with the LME49720 and LM4562 opamps. Of course getting some IC sockets as well to roll opamps if i wish to do so later.

Removed the 220pF loading caps on the MM stage as well.

We shall see what sort of change this brings.

oh, and that lead free solder is a biatch!

 

[sachu888]

Hi Sachi,
There is a good thread for recapping CA 640p at Audiokarma Recapping Cambridge Audio 640P Phono Preamp - AudioKarma.org Home Audio Stereo Discussion Forums

Regards,
Sachin

 

[sachi]

Interesting thread..seem to be doing exactly what i am doing! lol

Sachu, also picked up a tetra phono board that should arrive this week.

But will probably only get done with that sometime next month.