GoodSoundClub - Romy the Cat's Audio Site - The past seems more golden than it is

11-08-2020

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N-set
Gdansk, Poland
Posts 617
Joined on 01-07-2006

Post #:	1726
Post ID:	25977
Reply to:	25975

PP Issues

Steverino, I've asked same question to PurePower who kindly contacted me: If a moving around battery could have caused the issue? Waiting for the answer. My quick visual inspection did not show any obvious irregularities though.
Andrian, I've read you had a problem with your PP2000 charging unit years back (2009) "the audio circuit that the PP2000 was hooked up to was creating a problem as a ground loop within the PP2000 charging circuit. They have figured out a way to eliminate this but it requires making a new PCB to replace one in the PP2000. So they say they are going to make these and hopefully the replacement PCB will be given to me in a month." Has this been resolved?

Cheers,
Jarek
STACORE

11-08-2020

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drdna
San Francisco, California
Posts 526
Joined on 10-29-2005

Post #:	1728
Post ID:	25979
Reply to:	25977

Pure Power Ground Loop

N-set wrote:
They have figured out a way to eliminate this but it requires making a new PCB to replace one in the PP2000. So they say they are going to make these and hopefully the replacement PCB will be given to me in a month."

As some here may recall, after my PurePower failed catastrophically, I sent it back to Damian for repair. Eventually, after a long while, they admitted they had possibly sold my unit and offered a replacement. After another very long while, it arrived. The new unit no longer had the same buzzing problem. There was some noise, but this resolved with properly positioning the unit away from the phonograph.
I still contend any noise (when adding Pure Power), based on the experience of myself and others, might be coming from a component in the PurePower unit that is experiencing intermittent failure, possibly mechanically loose, cold-soldered, under-rated for its voltage/current requirements -- who knows -- but especially when it is an intermittent noise rather than a steady hum, it is something that should be checked out before you experience total failure of the unit.
Adrian

11-09-2020

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rickmcinnis
Posts 60
Joined on 10-18-2010

Post #:	1730
Post ID:	25986
Reply to:	25970

Masochism?

As one who loves this site for its vast information and the informed opinions of the proprietor I am fascinated by this thing which could be among the generator of the most number of responses here.
I open my email and there are a whole bunch of posts that should bring tears to my eyes from the lamentations but, then, this is audio so masochism is something we all engage in once addicted.

I have convinced myself I do not have power problems being in the northern suburbs of Atlanta but other than large isolation transformers - one for each channel - I have not ventured any further into this.
Needless to say reading of the trials and tribulations for EVERYONE who has purchased one of these things I can only assume they do something quite extraordinary that makes it worth the trouble.
OR it could be like that old story about British sports cars that they broke down so often because they knew their owners wanted to be needed
OR like a skit from Sat'dy Night Live when it was funny. Folks passing around a bottle of spoiled milk and sniffing it only to ask to smell it again. All the while going on and on about how horrible it smelled. Well, something like that.
I am especially distressed to hear of Dr. Gaw's experience. Inexcusable and disgusting.

11-10-2020

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rickmcinnis
Posts 60
Joined on 10-18-2010

Post #:	1733
Post ID:	25990
Reply to:	25989

You misunderstand

I am sorry it sounded like they bother me - far from it. I am glad to hear the sound of an active forum.
I was hoping the smile could be seen when reading my note.
It is just that with so many tales of woe from so few people one has to think that these things are downright mystical in their abilities.
I have no experience with what they can do. Of course, I take Romy's word for it. And Dr. Gaw's. I am not sure I would have the stamina to put up with such a cantankerous product and I do admire those who are as determined as you are to get the sound that you can enjoy.

11-12-2020

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N-set
Gdansk, Poland
Posts 617
Joined on 01-07-2006

Post #:	1734
Post ID:	25992
Reply to:	25990

Well...

...in my case the problem seems to be a GND loop *inside* my End of Life phono. Thanks to the continous help of PP Richard, I started to suspect the terrible noise I'm getting actually may be the charging voltage of the PP el caps (indeed it is 100Hz sawtooth-like with exponential tails). It is damped to GND and should normally disappear while in my phono it reappears. I plan to dismantle and examine the phono thoroughly. Not sure if that qualifies as mystical, but after hearing PP with my digital and FM, you want to sell your mother to make this unit work.

Cheers,
Jarek
STACORE

11-12-2020

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anthony
Posts 338
Joined on 08-18-2014

Post #:	1735
Post ID:	25993
Reply to:	25992

Deja vu

Jarek, because the PP introduces different grounding schema into your system I did suggest earlier that the phono may require alteration to suit. In my case, when the grounding schema was altered, one phono had a similar issue to yours and the solution there was to tie the phono chassis to signal ground just like they used to way back. It worked. Your solution may be similar, or it may be different, but I'm just putting it out there for you as something to try if it is not already setup that way...

Anthony

11-12-2020

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N-set
Gdansk, Poland
Posts 617
Joined on 01-07-2006

Post #:	1736
Post ID:	25994
Reply to:	25993

GND dances

Anthony, I didn't realize the potential of your remark, thank you. The chassis has been tied to the signal GND already at the birth as otherwise the phono would develop noise even off the wall. I have to go throroughly with a scope to see where the noise enters (not at the input RCA's - they are dead quiet).

Cheers,
Jarek
STACORE

11-14-2020

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Paul S
San Diego, California, USA
Posts 2,658
Joined on 10-12-2006

Post #:	1737
Post ID:	25995
Reply to:	25994

Neutral Bus Stand-Offs?

Jarek, what you describe can happen if anything with voltage touches the chassis, or something might be arcing across a very narrow gap. I have seen part leads that went too far through PCBs, also carelessly fitted stand-off. Even the axis of a choke or transformer can make a big difference in a phono stage.

Do let us know what it was when you figure it out.

Best regards,
Paul S

11-15-2020

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Paul S
San Diego, California, USA
Posts 2,658
Joined on 10-12-2006

Post #:	1738
Post ID:	25996
Reply to:	25995

An MIT Wonk Boils It Down

Here's a decent attempt to boil down basic "ground" issues. Generally speaking, according to best practices, grounding one's hi-fi is a systematic attempt to equalize the ground potential throughout the system at "zero". Again, phono stages are harder to deal with because of their high sensitivity combined with high gain. Include the cartridge, arm wiring, SUT and IC when considering the phono stage. My initial thought is that the PP changes the ground resistance for the phono stage, and that change is audible. Whether the change is a loop or just increasing resistance to where current "backs up" is for you to determine.

https://web.mit.edu/jhawk/tmp/p/EST016_Ground_Loops_handout.pdf

Hope this helps.

Best regards,
Paul S

11-15-2020

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Romy the Cat

Boston, MA
Posts 10,160
Joined on 05-28-2004

Post #:	1739
Post ID:	25997
Reply to:	25993

You get the idea….

I disagree with an idea that PP introduces different grounding schema into system. I mean it does and it does not. Anything the in your power pass induce different grounding schema and PP not different. I personally did not experiences that PP introduces any unexpected grounding schema, at least if you use PP in the system in the way I always do: no PP own ground is used in the system in any way of form. Let leave aside the probability that you specific PP is defective. If it is then all bets are off. If you have no problem with noise with the rest of you system but only your phonostage then it is most likely the problem with your phonstage. The fact the PP might highlights the problem is kind of irrelevant. Generally I recommend to ground everything to a main negative bass terminal that sits RCA jack. Still in real world each assembly is different, different step-up transformets schemas and zillion other variables.

It is impossible to debug it over internet. Jarek you can use the pattern the I use using my soldering period of my life. It is very effective and I always was able to found ground problems. Turn the playback on, max out the volume with your Phono on and observe whatever noise you feel you have. Solder 10-15 inch 10Ga wire to you negative grounded terminal. Then begin to tough diligent points of you circuitry with other sides of your wire. You very fast will find how to bridge you ground in order to get rid of you noise. You might hold that wire in hands and just short different pars of grounds, but your hands might act as own antenna. You get the idea….

"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche

11-15-2020

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drdna
San Francisco, California
Posts 526
Joined on 10-29-2005

Post #:	1740
Post ID:	25999
Reply to:	25997

Testing circuits for ground problems

Romy the Cat wrote:
Let leave aside the probability that you specific PP is defective. If it is then all bets are off.

Completely agree. And I will say from the forum members here who have a problem, Pure Power usually seem to be an internal defect. It is supported by the simple fact that WHEN your repaired/replaced unit arrives, the problem is gone.

Romy the Cat wrote:
If you have no problem with noise with the rest of you system but only your phonostage then it is most likely the problem with your phonostage.

Still, the phonostage can be notorious for amplifying any problems that exist. It is just the nature of it.

Romy the Cat wrote:
Solder 10-15 inch 10Ga wire to you negative grounded terminal. Then begin to touch diligent points of you circuitry with other sides of your wire. You very fast will find how to bridge you ground in order to get rid of you noise. You might hold that wire in hands and just short different pars of grounds, but your hands might act as own antenna.

This is a genius-level idea! It probably would have saved me many hours of re-flowing solder joints -- ROMY, you just made one of the crowning jewel comments of GoodSoundClub!
(Obviously, please disconnect the electricity and drain all capacitors before soldering. Also, make sure you are testing only ground points!)

Adrian

11-15-2020

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anthony
Posts 338
Joined on 08-18-2014

Post #:	1741
Post ID:	26001
Reply to:	25997

Alligator clips

Romy the Cat wrote:
Solder 10-15 inch 10Ga wire to you negative grounded terminal. Then begin to tough diligent points of you circuitry with other sides of your wire. You very fast will find how to bridge you ground in order to get rid of you noise. You might hold that wire in hands and just short different pars of grounds, but your hands might act as own antenna. You get the idea….

Yes, I did this just with alligator clips...very quick results...

11-16-2020

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N-set
Gdansk, Poland
Posts 617
Joined on 01-07-2006

Post #:	1742
Post ID:	26003
Reply to:	26001

Thank you

Thank you very much for all the help/advise. I'm still to investigate the problem. The working hypothesis is that my phono has some GND routing problem. Will examine it with the scope and shortening method to see if that's the case.

PP does damp its filter caps noise to GND, the info I got from PP (hope can publish):

"The charger and the input AC filter circuits both connect to incoming AC and both are connected to ground through their filter caps and therefore feed filtered noise to ground - where in a perfect ground system it would disappear from our life forever as intended."
Indeed, the noise at the output of my phono looks like charging voltage of a cap input filter (5ms base = 100Hz fundamental freq):
Output 5ms PP Online shorted MM.bmp

It is NOT present at the input RCA's and varies in amplitude depending which phono input I select (shorted MM smallest, Decca cart biggest).
Will let you know the results.

Cheers,
Jarek
STACORE

11-16-2020

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Paul S
San Diego, California, USA
Posts 2,658
Joined on 10-12-2006

Post #:	1743
Post ID:	26004
Reply to:	26003

Shield Unused Phono Jacks

Metal caps over phono stage unused RCA jacks can help with stray EMF/RFI. Cardas and others sell them.

Not saying something is wrong with the PP, just saying it doesn't take much to get noise from a phono stage, including any change in ground potential.

Paul S

11-16-2020

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N-set
Gdansk, Poland
Posts 617
Joined on 01-07-2006

Post #:	1744
Post ID:	26005
Reply to:	26004

Have them

The GND noise enters somewhere past the input RCA's. And this GND noise is not the PP RFI/EMF.

RFI/EMF of PP looks like this:
Output 5ms 2mV GND lifted PP Online Decca.bmp

Output 5ms 2mV GND lifted PP Online Decca.bmp

This one is caught by my Decca cart (phono GND lifted) but similar is present in the air, caught just by measuring cables. Time basis is still 5ms (vertical is 25x less than above). You can see the characteristic 'pumping' in regular periods (try to ignore the 50Hz hum).
That's probably the charger.

Cheers,
Jarek
STACORE

11-16-2020

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Paul S
San Diego, California, USA
Posts 2,658
Joined on 10-12-2006

Post #:	1745
Post ID:	26006
Reply to:	26005

Switched PS

Hmmm...

Whatever it is, if it's on the ground leg it "should" be possible to route it to ground before it gets in the amplifiers. Have you tried moving around a sheet of well grounded Mu metal, see if it catches and/or drops hum volume?

Paul S

11-24-2020

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N-set
Gdansk, Poland
Posts 617
Joined on 01-07-2006

Post #:	1746
Post ID:	26012
Reply to:	26006

Still fighting

My exorcisms to eliminate 100Hz PP induced noise in the EndOfLife phono gave no results so far.

- I took GND from the PP socket and tried connecting it to various GND points I could access (the signal GND plane, input sockets GND, the case). This only increased the noise.

- I tried connecting different GND points within the circuit. No results.

- The noise seems larger when the PP batteries are not 100% charged, suggesting it comes from the charger working (it disappears when the PP is in the battery mode)

- On the SUT inputs, the noise changes its amplitude with changing the orientation of the signal unit with respect to the power supply but never vanishes completely.

The last makes me suspect it might be emitted by the phono power supply and travel by the air to the signal unit. Perhaps PP excites the supply big chokes? But then why lifting the phono ground from the PurePower eliminates the noise completely?? Cannot understand it. Will get a scope tomorrow and try seeing where the noise enters.

Cheers,
Jarek
STACORE

11-25-2020

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N-set
Gdansk, Poland
Posts 617
Joined on 01-07-2006

Post #:	1747
Post ID:	26013
Reply to:	26012

Edit

- The noise has two phases - large noise and steady state noise. Large one ocures when the PP is switched offline and then switched on. This noise depends on the input (SUT or MM) and the orientation Signal enclosure vs power supply
- When the battery is fully charged, what remains is the steady state noise - much smaller. It doesn't seem to react to anything.
- Lifting the ground (disconnecting the signal ground from the chassis) has no effect

The only conditions so far to suppress the 100Hz noise are:
- Switching PP to the battery mode
- Disconnecting phono ground from the PP ground

Cheers,
Jarek
STACORE

11-25-2020

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steverino
Posts 367
Joined on 05-23-2009

Post #:	1748
Post ID:	26014
Reply to:	26013

All signs point

to the usual suspect.
I can certainly understand your reluctance to send the unit back for repair. I would not do so myself although since I have the older model they don't even support them in theory anymore. I think you have to take it to a local tech repair shop as I do mine. Typically what fails are standard things so I am pretty sure they can find out the part which is malfunctioning. It probably won't cost more than the back and forth shipping anyway.

11-25-2020

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Paul S
San Diego, California, USA
Posts 2,658
Joined on 10-12-2006

Post #:	1749
Post ID:	26015
Reply to:	26013

"Ground" ?

Jarek, when you say disconnecting the phono ground from the PP ground stops the noise, why is it you don't just do that? Are we confusing "ground" and "neutral again? If the phono stage works quietly when its ground is disconnected, why don't you just lift it? If it's star grounded in the first place, then the ground plane dumps out via the neutral wire, already, and the safety ground would make a loop, in any case. My own phono stage uses only the neutral wire for grounding (the safety ground is lifted). What am I missing here?

Paul S

11-26-2020

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N-set
Gdansk, Poland
Posts 617
Joined on 01-07-2006

Post #:	1750
Post ID:	26016
Reply to:	26015

Reasons

Paul, ground is ground, neutral is neutral. Where they are connected I have no idea, for sure not in my equipment. The case of my phono is connected to the safety ground not to the neutral. The reasons why I'm onto this and has not listened to the system for 2 weeks already:

A) check if my phono internal wiring is ok; perhaps I have some GND problem which PP highlighted; this becomes less and less of an option now
B) check if PP is ok or faulty as steverino suggests
C) Phono connection to GND is my only connection to the safety ground and I want to keep it

Cheers,
Jarek
STACORE

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