Regrounded the phono stage and wow... how about your systems?

[Peter Breuninger]

Ok, this is something I have been living with... a soft low level hum on LOMCs for the past year. I've been in other top system rooms and know that I am not alone. If I pick up the arm with the volume (way) up it's there, not frighteningly so but there it is, in all it's 60 cycle glory. If I go full gain it gets loud.

Last night I got the mojo to reexamine the system grounds, all of them... the three dedicated lines (two on opposite poles of the other) and three custom made junction boxes, plus each and every component. I took two (rather long) strands of pickup wire from the ground terminal of the phono stage and placed them on every possible ground location when suddenly on one component ground the hum vanished. I mean, completely vanished. To such a point I could turn the gain up to full with no additional hum than with the DACs.

Surprised at my cleverness I sat down to listen and (oh my) I was tear struck. The low level detail was simply extraordinary. I bought a Phillips box set of Schubert symphonies at T.H.E. Show Newport, in digital no less and now when I play them (they were completely unlistenable before the change) it's like I'm at the concert. I hear every instrument, every detail.

So I beg the question to us vinyl guys.. do you have hum at gain? Can you turn it up all the way without any hum?

 

[microstrip]

You are right - hum can spoil the resolution of a system, even if it seems it is low enough for not disturbing you at the listening position. Systems using MC cartridges are very sensitive to it.

My advice - use a spectral analyzer to diagnose hum in your system and tune the grounding system. Get a good usb 24 bit soundcard (I use an EMU Tracker Pre, any similar one will do) and some spectral analysis software - the demo version of Spectraplus is great, but you will be able to use it free only for 30 days. Connect it to the tapeout output of your preamplifier and look at the 50 or 60 Hz peak. You will be astonished how even routing a wire can decrease it - the instrument is much more sensitive and reliable that just listening. Fight with the grounding wires and schemes until your hum is at less -80dB.

If possible, while optimizing have your laptop operating with the battery and disconnect the charger - using the mains supply can introduce some hum!

 

[MylesBAstor]

Ok, this is something I have been living with... a soft low level hum on LOMCs for the past year. I've been in other top system rooms and know that I am not alone. If I pick up the arm with the volume (way) up it's there, not frighteningly so but there it is, in all it's 60 cycle glory. If I go full gain it gets loud.

Last night I got the mojo to reexamine the system grounds, all of them... the three dedicated lines (two on opposite poles of the other) and three custom made junction boxes, plus each and every component. I took two (rather long) strands of pickup wire from the ground terminal of the phono stage and placed them on every possible ground location when suddenly on one component ground the hum vanished. I mean, completely vanished. To such a point I could turn the gain up to full with no additional hum than with the DACs.

Surprised at my cleverness I sat down to listen and (oh my) I was tear struck. The low level detail was simply extraordinary. I bought a Phillips box set of Schubert symphonies at T.H.E. Show Newport, in digital no less and now when I play them (they were completely unlistenable before the change) it's like I'm at the concert. I hear every instrument, every detail.

So I beg the question to us vinyl guys.. do you have hum at gain? Can you turn it up all the way without any hum?

No and yes. Right now the Doshi, Allnic, Avid and cj are all hum free Now just watch

Find the hum issue greatly depends upon the arm and phono section. Many times can leave the cartridge ungrounded and it's fine; then every once in a while when putting a new cartridge or phono section in, need to ground. Sometimes though the hum can be as innocuous as an IC placed too closely to a PC (that also generally leads to a brighter sound among other things!).

 

[mep]

I certainly have had hum in my system with phono preamps and tonearms (and just read all of my Krell Sagas for a different story of hum). The ET-2 arm is super susceptible to hum as it has no true ground. Combine that with a Counterpoint SA-2 and you have some hum fun to contend with. Now that I’m using an SME 312s into a Krell KPE Reference phono stage into the Krell KBL, I have no hum in my phono section. I have been on a mission for the last year or so to get rid of all hum and drive the noise floor down as low as I can get it. I now have no hum and my noise floor is very, very low.

I ended up using a piece of copper bus bar with some holes drilled and tapped into it so I could star ground my components to the bus bar.

 

[Mike Lavigne]

there have been times in the past where i've dealt with hum to a some degree. the worst was when i had 5 tonearms and cartridges all set up at once, and 4 of them going to the Allnic H3000. one ground post and 4 ground wires. and then Joel Durand comes over and we are switching tonearms back and forth. sheeesh! how can you keep all 4 ground wires on the same small ground post on the back of the unit on the bottom shelf?

another time was when i had a piece of ground wire attached to the screw on my duplex outlet without anything attached to it. it was acting like an antenna and picking up noise from my lights. it took forever to figure it out.

then there was the time i tried to use an Allnic step up device to add another LOMC input to the H3000. lots of hum, likely a ground loop someplace. i ended up just using a MM cartridge without the step up.

then another was with my Rockport Sirius III. since it had an air suspension, an air bearing for the platter, and an air bearing on the arm....there was no place for the ground to connect. i had to wrap a ground wire around one of the RCA outputs and ground that to my dart preamp.

since i've had the Equi=tech the last couple of years i've had zero hums.....balanced power and the noise rejection that comes with that. my only phono stages now are internal inside the darTZeel preamp, and both my tonearms have one tonearm wire from cartridge clips to phono stage. most of the potential hum issues are simply eliminated.

and when i did have hums i took your approach. i just kept trying different things until it went away.

 

[Bill Hart]

I went through the tortures of the damned to eliminate a very low level 60hz hum through the Avantgardes. I originally attributed this in part to the different ground potential of the separate dedicated lines combined with the different internal grounding schemes of the various components. I bought one of those Ground Zero devices from Granite Audio 5 or 6 years ago and it essentially allows you to create a 'faux' star ground among the components that are connected to it, and allows you to connect the components to different sections of the device, each of which has a separate 3 way switch for altering the impedence of the ground, relative to other components hooked up to a different section of the device. It helped, but still did not eliminate the low level hum. I finally determined that it had nothing to do with the tone arm to phono stage or phono stage to line stage, and lifted the grounds at each component as well to see where the problem existed. I isolated it to the line stage to amp connection. Those components are both made by Lamm. They are connected using XLR interconnect, although I understand that, at least at the amp end, an ML2, the XLR input is not truly 'balanced.' Lifting the grounds of the amps makes the problem disappear. When I first bought the amps, used, from a Lamm dealer, I did not have the problem. It was only after I sent them to Vlad to be checked, and have the on/off switches and a tube socket replaced, that the hum became evident. What I discovered was that the original owner (these are pretty early ML2s, i think) had lifted the chassis ground internally, and when Vlad went over the amps at "Lamm Industries," he reinserted the ground connection. That's when the hum started. What is not entirely explicable to me is how the Ground Zero can really star ground the various components if each is also grounded through its 3 pin wall connection. Or whether, by lifting the ground on the power amp plug, for example, but having it grounded through the Ground Zero device (which has a passive plug that plugs the GZ device into the grounding pin of a wall socket), that is really grounding the amps. Sorry to raise more questions than I answered. I find grounding issues to be devilish in the extreme.

 

[MylesBAstor]

Posted this awhile back and it might still be pertinent.

Thanks to this advice from Jim Weill of Sound Applications:

If I might suggest, your customers might also benefit from taking the AC problem one step closer to the circuit breaker box. Audiophiles might be advised to hire an electrician (and insist on the following) and have them check that the AC lines running to their equipment is on the same leg - otherwise the power transformers will be 180 degrees out of phase and as a result, can increase the noise floor and produce ground loop hum. Another might be for the electrician to measure the power factor on the two legs and select the better of the two. Finally, the electrician can clean the connections and retorque them.

 

[Bill Hart]

Posted this awhile back and it might still be pertinent.

Thanks to this advice from Jim Weill of Sound Applications:

If I might suggest, your customers might also benefit from taking the AC problem one step closer to the circuit breaker box. Audiophiles might be advised to hire an electrician (and insist on the following) and have them check that the AC lines running to their equipment is on the same leg - otherwise the power transformers will be 180 degrees out of phase and as a result, can increase the noise floor and produce ground loop hum. Another might be for the electrician to measure the power factor on the two legs and select the better of the two. Finally, the electrician can clean the connections and retorque them.

Myles, did all that, and more, including a separate subpanel (which I believe, but cannot verify without my electrician who sadly died in a motorcycle accident a few years ago - although i could conceivably bring someone else in to pull off the covers of the panels) that sees the juice before the rest of house breakers; installed 10 amp wire to good, but not crazy expensive 20 amp hospital grade Hubbell receptacles (Porter Ports); additional grounding rod (but the subpanel also had to go to the same ground as the main panel per code); made sure everything was in phase all the way up, etc.
Two things remained. The system was not isolated from other crap in the main house system, e.g. noisy low intensity lighting in the kitchen, or a humdifier plugged into a bedroom outlet on another floor). Second, it did not cure grounding differences among components. Granted, I do not think the various dedicated lines share the same ground- they are all 'home runs' from the outlet directly to the subpanel. This is one reason why I am seriously considering an Equi=Tech wall cabinet for my next room. Even that may not cure all ills, but it may get me closer. And I want surge protection. I just haven't liked the effect of the component -sized conditioners/surge protectors that i've tried (i have not tried all of them, not any regenerators. I gather that the Silver Circle or whatever it is called that you like may in part be good because it contains a fairly large isolation transformer, right?) I have a big 240 step down that I use for the home theatre, but i've never tried it for the audio system components. However, it was the only thing that DID eliminate the nasty electrical 'zap' from from tone arm pump everytime the pump cycled. (I had an extra dedicated line put in just for that, and it didn't help).

 

[bblue]

I certainly have had hum in my system with phono preamps and tonearms (and just read all of my Krell Sagas for a different story of hum). The ET-2 arm is super susceptible to hum as it has no true ground. Combine that with a Counterpoint SA-2 and you have some hum fun to contend with. Now that I’m using an SME 312s into a Krell KPE Reference phono stage into the Krell KBL, I have no hum in my phono section. I have been on a mission for the last year or so to get rid of all hum and drive the noise floor down as low as I can get it. I now have no hum and my noise floor is very, very low.

I ended up using a piece of copper bus bar with some holes drilled and tapped into it so I could star ground my components to the bus bar.

Mep, the ET-2 kinda sorta has a ground through it, but it's not obvious and quite subject to improvement. The cabling from the headshell to air spindle 5 pin connector has the tonearm cable shield tied to the middle pin. Depending on how the spindle was put together, there should be a conductive path from the center pin to the spindle. I've seen three different ET-2's and that point was not always connected, and also had no ground return connected to it.

On mine, I got rid of the notion of the conductive strip on the middle pin, and carried that pin to the other end of the spindle, made a one-turn loop that sits in the plastic 'seat' that holds the weight system and has the spindle pushing against the wire loop when it is tightened. That takes care of the spindle. Then I extend that connection out with the 4 conductor tonearm wiring to the junction box and on to the preamp chassis (separately of the TT ground). That quiets it for the most part. The only weak area is the 4 conductor audio wiring that is unshield between the rear of the spindle and the junction box. That can really be a wonderful antenna for all sorts of junk to enter the system. Just that 5" or so picks up hum radiated from an AC motor and also hum + sidebands from my overhead LED lighting.

I'm working on a braided litz wire solution for that area which should help immensely, but we'll see.

How have you dealt with continuity of the grounding system through the arm and spindle?

Like Mike L, I'm using Equi=Tech balanced power conditioners, sourced from the same AC Phase to power all audio equipment, with an earth ground, and that quiets everything, except induced hum from the tonearm wiring. No current loop hums even from unbalanced connections. It's wonderful how much that helps.

--Bill

 

[bblue]

...
Last night I got the mojo to reexamine the system grounds, all of them... the three dedicated lines (two on opposite poles of the other) and three custom made junction boxes, plus each and every component. I took two (rather long) strands of pickup wire from the ground terminal of the phono stage and placed them on every possible ground location when suddenly on one component ground the hum vanished. I mean, completely vanished. To such a point I could turn the gain up to full with no additional hum than with the DACs.

I have traditionally always made sure that all audio related equipment in a given area had power originated from the same AC phase (Poles, as you're calling them) to minimize the possible AC potential between components. That usually helps a lot, but sometimes unplugging all the components, and starting with a power amp (with an ungrounder on the AC plug) use an AC Voltmeter to measure the voltage generated between the chassis and its would-be ground, orienting the AC plug for minimum voltage, then reconnect the ground and plug it in. Then on to the next piece, rinse and repeat. There are other variations of this that can be applied, but that's how I start out.

Have you analyzed what path connected to which ground cause the hum to disappear and why?

You're right, though, having absolutely no ground current between system components is the only way to achieve the best audio for your system. Makes a huge difference -- balanced or unbalanced audio. That doesn't apply just to 60Hz and its harmonics, either.

Sometimes though, you can end up with ground current through the system that just happens to get nulled out by a combination of connections. Even though it is nulled at that moment, you're still not at an optimum point. It has to all be *really* gone.

--Bill

 

[Peter Breuninger]

Interesting thread responses so far.

My electrician and DIY audio friend quivers when I ask him about ground loops. I think the essence of my thread is that these low level hums are wreaking havoc with our systems and unless you 100% eliminate them you; 1) have no idea how good you system can be, and I'm sorry to have to say this but, 2) you should not be reviewing audio equipment.

My quest for "silence" was born with my newest review project, the Onedof table. In fact, it began last year when a well known manufacturer sent me a phono stage to review. I could never get the 60hz hum to acceptable levels and I had to take a pass. Now I realize there are no acceptable levels... you have to have complete dead silence.

I have now achieved this and it has changed my view on phono front ends and on reporting about phono based front ends. Forget about putting a stethoscope on your turntable or rapping your knuckles on the stand, it's meaningless if your phono system has a-n-y hum at full gain (gates wide open), IMHO.

 

[MylesBAstor]

I have traditionally always made sure that all audio related equipment in a given area had power originated from the same AC phase (Poles, as you're calling them) to minimize the possible AC potential between components. That usually helps a lot, but sometimes unplugging all the components, and starting with a power amp (with an ungrounder on the AC plug) use an AC Voltmeter to measure the voltage generated between the chassis and its would-be ground, orienting the AC plug for minimum voltage, then reconnect the ground and plug it in. Then on to the next piece, rinse and repeat. There are other variations of this that can be applied, but that's how I start out.

Have you analyzed what path connected to which ground cause the hum to disappear and why?

You're right, though, having absolutely no ground current between system components is the only way to achieve the best audio for your system. Makes a huge difference -- balanced or unbalanced audio. That doesn't apply just to 60Hz and its harmonics, either.

Sometimes though, you can end up with ground current through the system that just happens to get nulled out by a combination of connections. Even though it is nulled at that moment, you're still not at an optimum point. It has to all be *really* gone.

--Bill

What do you do if you find the plug polarity is reversed (and I still have the old Namiki or wand you hold over the transformer too)? For instance, I've even found phase in one monoblock reversed compared to its companion. Do you use a cheater plug or reverse at the wall? The reason I ask is that the cheater plug is another example of the cure being worse than the disease. Every cheater plug I've tried brightens the sound and adds a hashiness/graininess to the sound. Or did you make your own cheater plug

 

[MylesBAstor]

Interesting thread responses so far.

My electrician and DIY audio friend quivers when I ask him about ground loops. I think the essence of my thread is that these low level hums are wreaking havoc with our systems and unless you 100% eliminate them you; 1) have no idea how good you system can be, and I'm sorry to have to say this but, 2) you should not be reviewing audio equipment.

My quest for "silence" was born with my newest review project, the Onedof table. In fact, it began last year when a well known manufacturer sent me a phono stage to review. I could never get the 60hz hum to acceptable levels and I had to take a pass. Now I realize there are no acceptable levels... you have to have complete dead silence.

I have now achieved this and it has changed my view on phono front ends and on reporting about phono based front ends. Forget about putting a stethoscope on your turntable or rapping your knuckles on the stand, it's meaningless if your phono system has a-n-y hum at full gain (gates wide open), IMHO.

I think you can throw in the old days of not having enough gain in a tube based phono sections and having to endure hiss when using a low output MC cartridge. There's no excuse for that anymore.

 

[Peter Breuninger]

I think you can throw in the old days of not having enough gain in a tube based phono sections and having to endure hiss when using a low output MC cartridge. There's no excuse for that anymore.

I'm with ya brother.

 

[bblue]

What do you do if you find the plug polarity is reversed (and I still have the old Namiki or wand you hold over the transformer too)? For instance, I've even found phase in one monoblock reversed compared to its companion. Do you use a cheater plug or reverse at the wall? The reason I ask is that the cheater plug is another example of the cure being worse than the disease. Every cheater plug I've tried brightens the sound and adds a hashiness/graininess to the sound. Or did you make your own cheater plug

Are you saying that with two identical mono blocks, the AC phase connections from AC input to the transformer are backwards from each other? I'd find that extremely unusual. It would seem to indicate a manufacturing error.

But in that situation, if it was me I would modify the wiring so they are both the same and that sameness also represents the lowest voltage offset between each mono block and the AC supply ground.

You're right, I would never use ground cheaters in a normal situation, but I have been known to make my own if it was simpler to reverse the AC pair in the cheater than in the equipment. The other approach (not U.L. approved) would be to lift the ground pin (cheater-like) but add a hefty ground wire from the chassis (or common) to the other equipment. As long as you have a solid ground reference for each device it doesn't much matter if it is part of the AC cable or not (except for AC safety regulations).

Since I've been using the Equi=Tech balanced power I haven't had to pay much attention to AC polarity or grounding (other than the Equi=Tech's themselves). Just plug in everything with its standard three wire cable (or preferably a heavier third party AC cable) and go. Sometimes wire placement needs some adjustment, but not often.

--Bill

 

[bblue]

Interesting thread responses so far.

My electrician and DIY audio friend quivers when I ask him about ground loops. I think the essence of my thread is that these low level hums are wreaking havoc with our systems and unless you 100% eliminate them you; 1) have no idea how good you system can be, and I'm sorry to have to say this but, 2) you should not be reviewing audio equipment.

My quest for "silence" was born with my newest review project, the Onedof table. In fact, it began last year when a well known manufacturer sent me a phono stage to review. I could never get the 60hz hum to acceptable levels and I had to take a pass. Now I realize there are no acceptable levels... you have to have complete dead silence.

I have now achieved this and it has changed my view on phono front ends and on reporting about phono based front ends. Forget about putting a stethoscope on your turntable or rapping your knuckles on the stand, it's meaningless if your phono system has a-n-y hum at full gain (gates wide open), IMHO.

I think this might be a little overstated. It's important to understand what the source of hum might be. Hum that is not the result of a ground loop, but rather is induced magnetically is usually not significant (electrically) as long as it cannot be heard while your source is playing. If it's a turntable, a -70db hum is not likely to be heard in surface noise and does not imply any degradation, since it's just audio at that point.

If the hum is caused by ground loops indicating that current is flowing between chassis and/or within audio connections, it's definitely cause for concern and will affect the sound at any level.

If you're not sure, yes, better there is no hum at all (when possible). But you can't correct induced hum by changing grounding, or vice versa. One way to tell the difference in many cases is to note whether the hum is all the deep fundamental 50Hz or 60Hz pitch with no harmonics. If so, it will usually be induced. If the hum has a low fundamental pitch but has higher pitched tones mixed in with it (harmonics) it is most likely to be caused by ground loops of some sort.

--Bill

 

[MylesBAstor]

Are you saying that with two identical mono blocks, the AC phase connections from AC input to the transformer are backwards from each other? I'd find that extremely unusual. It would seem to indicate a manufacturing error.

Yes, happened 15-20 years ago before people really paid attention to that detail. Even so, always check because have found that happen in monoblocks from several companies.

--Bill[/QUOTE]

 

[ack]

Ok, this is something I have been living with... a soft low level hum on LOMCs for the past year. I've been in other top system rooms and know that I am not alone. If I pick up the arm with the volume (way) up it's there, not frighteningly so but there it is, in all it's 60 cycle glory. If I go full gain it gets loud.

Last night I got the mojo to reexamine the system grounds, all of them... the three dedicated lines (two on opposite poles of the other) and three custom made junction boxes, plus each and every component. I took two (rather long) strands of pickup wire from the ground terminal of the phono stage and placed them on every possible ground location when suddenly on one component ground the hum vanished. I mean, completely vanished. To such a point I could turn the gain up to full with no additional hum than with the DACs.

Surprised at my cleverness I sat down to listen and (oh my) I was tear struck. The low level detail was simply extraordinary. I bought a Phillips box set of Schubert symphonies at T.H.E. Show Newport, in digital no less and now when I play them (they were completely unlistenable before the change) it's like I'm at the concert. I hear every instrument, every detail.

So I beg the question to us vinyl guys.. do you have hum at gain? Can you turn it up all the way without any hum?

I am not sure yet I would characterize what I have as hum - if I turn the volume all the way up there is low, mid and high frequency hiss/noise of equal intensity, so this is probably just noise across the entire spectrum. If I touch the arm or anything else relating to phono (including the XLR interconnects), the levels don't go up; but if I remove the grounding (by using an XLR-to-RCA converter and then RCA interconnects with no ground) there is PLENTY of hum at almost any volume setting. Connecting the phono stage's ground terminal to anything else doesn't improve this noise. I have conducted numerous connectivity/continuity tests with my Fluke meter, and the arm is properly connected to the phono's ground with the XLR interconnects. However - get this - with the turntable completely disconnected I can measure 44Mohms resistance between the arm and/or XLR junction box and the phono's ground terminal which is about 1m away, as if current flows through the air.

Having said that, there is one test that does pick up hum, and that's the phono's input RCAs, _if_ I touch them even with the table connected to the phono stage with XLRs (which provides the grounding); I measure 0.773Mohms between the RCA negative and any ground. So this tells me my phono stage is probably susceptible to hum and it picks up some from the input RCAs (which are wrapped with electrical tape, but still) from the environment (including the surrounding power cords, which despite the fact they are all shielded, there is still leakage from the IEC connectors). I have thought of actually disconnecting the RCA jacks inside the phono stage and I think this thread gives me the impetus to do it.

 

[ack]

I have thought of actually disconnecting the RCA jacks inside the phono stage and I think this thread gives me the impetus to do it.

Come to think of it, a better solution is to add a load to the RCA inputs (this is how you do custom cartridge loading with the Ayre anyway - you utilize the unused input to add custom impedance loading); so a resistor of 100kohm or 1Mohm should do the job... we'll see what happens to the noise after this mod, probably not much, I suspect.