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Author Topic: Audiophile issues  (Read 579 times)

hbelkins

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Audiophile issues
« on: June 28, 2022, 01:56:40 PM »

This thread is for people to discuss their stereo systems and issues they may be having with them.

I recently unearthed my 1980s vintage component stereo system -- well, most of it anyway. I received a Technics receiver, turntable, and speakers as a college graduation present. I added a cassette deck about a year later.

Uncovered were the receiver and original cassette deck, as well as an auxiliary set of Panasonic speakers I'd come across during that time. Not discovered were the turntable (no idea where it is; I thought it would be with the rest of the system), the original speakers, the dual cassette deck to which I upgraded in the late 1980s, and the CD player I bought during that timeframe.

I hooked the receiver and cassette deck up and everything worked perfectly. I bought a connector that allows me to hook up a portable CD player, phone, tablet, or MP3 player, and it works well too.

I ordered a turntable and decided on a Victrola VPRO-2000 as it offered a good set of features for the price. Unfortunately, I've run into a persistent issue that I can't see to correct, and the manufacturer recommends that I return it to the seller.

There's a persistent humming when the turntable is plugged in to the PHONO jacks of the receiver. I've looked at several online troubleshooting sites and have tried all the suggestions but it doesn't solve the problem. I suspect it's a grounding issue. The old Technics turntable had a GND connection that attached to a ground on the receiver. The new Victrola doesn't have a GND port. I bought a ground loop isolator to plug into the audio cables (RCA cables) but it didn't solve the problem.

The turntable has a switchable preamp, and when I turn it on and plug it into the AUX audio jacks on the receiver, the hum is not present. Only when used with the PHONO jacks. I also tried it on another receiver with the same hum present.

Interestingly enough, the hum is present when the turntable is plugged into the PHONO jacks even if it is turned off and disconnected to AC power. If there is nothing plugged into the PHONO jacks, the hum disappears.

At this point I think it's a grounding issue because the old Technics turntable with the GND connection never had that issue. I'm at a loss to solve the problem and I hate to return it for a replacement if the issue is the fact the turntable doesn't have a grounding connection.

I don't plan to jump on the revived vinyl craze -- I still prefer CDs because you don't get imperfections in the sound like scratches or dust on the records -- but I've got gobs of albums from the 70s and 80s, some of which were never issued on CD so there's no digital version available.
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kalvado

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Re: Audiophile issues
« Reply #1 on: June 28, 2022, 03:09:37 PM »

as for grounding, most of US electric stuff is grounded through a third terminal on a plug. Apparently, that is for plugs which have that 3 pin anyway.
Shield of an audio cable should be grounded as well. So what I would do: check if outer part of tullip or top ring on three-band connector is connected to power ground, and how power grounds are actually connected between two devices.
it may be less than a trivial question what is the best case, especially if they go into different outlets
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Dirt Roads

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Re: Audiophile issues
« Reply #2 on: June 28, 2022, 05:58:03 PM »

as for grounding, most of US electric stuff is grounded through a third terminal on a plug. Apparently, that is for plugs which have that 3 pin anyway.
Shield of an audio cable should be grounded as well. So what I would do: check if outer part of tullip or top ring on three-band connector is connected to power ground, and how power grounds are actually connected between two devices.
it may be less than a trivial question what is the best case, especially if they go into different outlets

What you are talking about is the extra earth wire (called ground) that is used as a return in case of a power fault.  That is plugged into an earth grid that will somewhere be connected to a ground rod that is directly connected into the earth.  If done properly, the same earth grid can be used as a bypass route to protect against lightning.

Electronics also have a frame connection (also called ground) that can be connected to the earth grid.  Often, electronic components are wired with one power wire and one stubby wire to the closest frame connection as a power return.  If you interconnect any of the electronic controls from one box to another, you need to interconnect those frames as well for the control power to return to its respective power supply.  That's what hbelkins called the GND port.

Then, you've got a whole different concept of the frame being used as a means of controlling electro-magnetic interference (EMI) and radio frequency interference (RFI).  We still call it "ground", well because it uses the same electrical connectors as all of those other thingys called "ground". 

If you aren't careful, any particular electrical network can end up with a bunch of different "grounds", some of which are neutral, some of which are at a differential compared to the others (usually low voltage), some which are current carrying (almost always very low current), and some which are fully of noise.  The low current will take the path of least resistance and go round in circles, sometimes where you don't want electricity to go.  Stereos with different equipment types are sometimes a problem, but I usually see these issues where battery chargers and radio equipment camp out in the same place.
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Dirt Roads

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Re: Audiophile issues
« Reply #3 on: June 28, 2022, 06:14:00 PM »

The turntable has a switchable preamp, and when I turn it on and plug it into the AUX audio jacks on the receiver, the hum is not present. Only when used with the PHONO jacks. I also tried it on another receiver with the same hum present.

Interestingly enough, the hum is present when the turntable is plugged into the PHONO jacks even if it is turned off and disconnected to AC power. If there is nothing plugged into the PHONO jacks, the hum disappears.

That "hum" is almost always induced third-harmonic voltage from an adjacent power cable or power supply somewhere.  I'm wondering if the something on your main tuner/amplifier setup is causing EMI on your new turntable, and when you push the signal through its preamp the turntable's filter cleans it up.

Try to relocate the power cord for the turntable further away from power cords going to the other devices.  Also try to relocate the power cord for the turntable further away from RCA cable going to the PHONO jacks.  Also, it might not hurt to take that RCA cable loose and twist the wires a bunch of times before reconnecting (at least two twists per foot will neutralize 60Hz and 180Hz bleedoff, but you probably don't need quite so many twists for this). 

If that doesn't work, you are probably going to need to separate the turntable away from your main tuner/amplifier. 
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kalvado

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Re: Audiophile issues
« Reply #4 on: June 28, 2022, 07:26:12 PM »

as for grounding, most of US electric stuff is grounded through a third terminal on a plug. Apparently, that is for plugs which have that 3 pin anyway.
Shield of an audio cable should be grounded as well. So what I would do: check if outer part of tullip or top ring on three-band connector is connected to power ground, and how power grounds are actually connected between two devices.
it may be less than a trivial question what is the best case, especially if they go into different outlets

What you are talking about is the extra earth wire (called ground) that is used as a return in case of a power fault.  That is plugged into an earth grid that will somewhere be connected to a ground rod that is directly connected into the earth.  If done properly, the same earth grid can be used as a bypass route to protect against lightning.

Electronics also have a frame connection (also called ground) that can be connected to the earth grid.  Often, electronic components are wired with one power wire and one stubby wire to the closest frame connection as a power return.  If you interconnect any of the electronic controls from one box to another, you need to interconnect those frames as well for the control power to return to its respective power supply.  That's what hbelkins called the GND port.

Then, you've got a whole different concept of the frame being used as a means of controlling electro-magnetic interference (EMI) and radio frequency interference (RFI).  We still call it "ground", well because it uses the same electrical connectors as all of those other thingys called "ground". 

If you aren't careful, any particular electrical network can end up with a bunch of different "grounds", some of which are neutral, some of which are at a differential compared to the others (usually low voltage), some which are current carrying (almost always very low current), and some which are fully of noise.  The low current will take the path of least resistance and go round in circles, sometimes where you don't want electricity to go.  Stereos with different equipment types are sometimes a problem, but I usually see these issues where battery chargers and radio equipment camp out in the same place.
And when was last time you saw disconnected signal ground and chassis ground on a consumer-grade product?
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1995hoo

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Re: Audiophile issues
« Reply #5 on: June 28, 2022, 08:01:06 PM »

You could also try adding an outboard phono preamp. Connect the turntable to the phono preamp, then connect that device to the receiver anywhere EXCEPT the Phono input. I have a Rotel phono preamp I quite like, though I don’t know the model number off the top of my head (I’m in New York tonight) and I’m sure it’s been discontinued anyway. It was not too expensive, though, certainly less than $250.
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bwana39

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Re: Audiophile issues
« Reply #6 on: June 28, 2022, 09:04:30 PM »

This thread is for people to discuss their stereo systems and issues they may be having with them.

I recently unearthed my 1980s vintage component stereo system -- well, most of it anyway. I received a Technics receiver, turntable, and speakers as a college graduation present. I added a cassette deck about a year later.

Uncovered were the receiver and original cassette deck, as well as an auxiliary set of Panasonic speakers I'd come across during that time. Not discovered were the turntable (no idea where it is; I thought it would be with the rest of the system), the original speakers, the dual cassette deck to which I upgraded in the late 1980s, and the CD player I bought during that timeframe.

I hooked the receiver and cassette deck up and everything worked perfectly. I bought a connector that allows me to hook up a portable CD player, phone, tablet, or MP3 player, and it works well too.

I ordered a turntable and decided on a Victrola VPRO-2000 as it offered a good set of features for the price. Unfortunately, I've run into a persistent issue that I can't see to correct, and the manufacturer recommends that I return it to the seller.

There's a persistent humming when the turntable is plugged in to the PHONO jacks of the receiver. I've looked at several online troubleshooting sites and have tried all the suggestions but it doesn't solve the problem. I suspect it's a grounding issue. The old Technics turntable had a GND connection that attached to a ground on the receiver. The new Victrola doesn't have a GND port. I bought a ground loop isolator to plug into the audio cables (RCA cables) but it didn't solve the problem.

The turntable has a switchable preamp, and when I turn it on and plug it into the AUX audio jacks on the receiver, the hum is not present. Only when used with the PHONO jacks. I also tried it on another receiver with the same hum present.

Interestingly enough, the hum is present when the turntable is plugged into the PHONO jacks even if it is turned off and disconnected to AC power. If there is nothing plugged into the PHONO jacks, the hum disappears.

At this point I think it's a grounding issue because the old Technics turntable with the GND connection never had that issue. I'm at a loss to solve the problem and I hate to return it for a replacement if the issue is the fact the turntable doesn't have a grounding connection.

I don't plan to jump on the revived vinyl craze -- I still prefer CDs because you don't get imperfections in the sound like scratches or dust on the records -- but I've got gobs of albums from the 70s and 80s, some of which were never issued on CD so there's no digital version available.

It has been while, but a turntable has its own phono plugs on the receiver that are properly biased fo rthe turntable.
That said, you appear to have a turntable with a preamp. You may need ot turn it off. .
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Dirt Roads

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Re: Audiophile issues
« Reply #7 on: June 28, 2022, 09:27:47 PM »

And when was last time you saw disconnected signal ground and chassis ground on a consumer-grade product?

Good question.  Devices that are interconnected with either USB or HDMI do indeed interconnect the signal ground and chassis ground.  But none of the devices that use two-prong power cords have a power ground whatsover, and most devices that use off-board transformer "bricks" don't pass the power ground either.  To be honest, I don't like mixing any of these grounding systems.  I've had too many failure modes that result in loose power that floats from one subsystem to another and then returns from the negative of one power supply through the negative of another power supply via the chassis ground: hence the term ground loop.  Often, the result is something like a control wire carrying 12VDC also "carrying" 5VDC in the opposite direction. 

On the old stereo devices that have two-prong power cords and RCA jacks, the outer ground jacket is often connected to a "Synch Ground" bus that interconnects the ground wire for each RCA cable similar to a VGA connector.  But that is seldom connected to the signal ground or chassis ground, hence the need to have a separate GND patch wire between the tuner/amp and the other devices.  But I'm not sure that any of that is involved with the "hum" that hbelkins is getting on the RCA input from his new turntable on his old tuner/amp.

I'm curious.  I've never seen any stereo equipment that has a three-wire power cable (with a separate power ground wire).  Do you have any experience with any brands that do have such?
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kalvado

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Re: Audiophile issues
« Reply #8 on: June 29, 2022, 09:32:51 AM »

And when was last time you saw disconnected signal ground and chassis ground on a consumer-grade product?

Good question.  Devices that are interconnected with either USB or HDMI do indeed interconnect the signal ground and chassis ground.  But none of the devices that use two-prong power cords have a power ground whatsover, and most devices that use off-board transformer "bricks" don't pass the power ground either.  To be honest, I don't like mixing any of these grounding systems.  I've had too many failure modes that result in loose power that floats from one subsystem to another and then returns from the negative of one power supply through the negative of another power supply via the chassis ground: hence the term ground loop.  Often, the result is something like a control wire carrying 12VDC also "carrying" 5VDC in the opposite direction. 

On the old stereo devices that have two-prong power cords and RCA jacks, the outer ground jacket is often connected to a "Synch Ground" bus that interconnects the ground wire for each RCA cable similar to a VGA connector.  But that is seldom connected to the signal ground or chassis ground, hence the need to have a separate GND patch wire between the tuner/amp and the other devices.  But I'm not sure that any of that is involved with the "hum" that hbelkins is getting on the RCA input from his new turntable on his old tuner/amp.

I'm curious.  I've never seen any stereo equipment that has a three-wire power cable (with a separate power ground wire).  Do you have any experience with any brands that do have such?
It's been a while since I dealt with anything audio...
IEC insulation class I vs class II is a long story. I am used to grounding signals; although that may create issues apparently. Differential pairs are there for a reason.
FOr 1980's vintage, it is most likely a linear power supply  - and with degraded capacitors, of course. That may be a separate can of worms. 
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hbelkins

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Re: Audiophile issues
« Reply #9 on: June 29, 2022, 11:39:16 AM »

None of my audio components have the third plug. They're only two-wire cords/plugs.

The turntable has a switchable preamp and I keep it turned off when it's plugged into the PHONO jacks. There is no hum if I turn the preamp on and plug it into the AUX port of the receiver.

I've done the jiggling/twisting thing and separated the cords as much as possible.

I really suspect the issue is the fact that the turntable doesn't have a GND connector. If the input is switched to "phono" with nothing plugged in to the PHONO RCA jacks, no hum is present. But if an RCA audio cable is plugged in to the jacks, even if it is not plugged into a component, the hum returns.

I can work around it by using the AUX port and turning the preamp on, but that eliminates an audio port. I actually have a Realistic 8-track player I'd like to connect because I have some old vintage 8-tracks I'd like to digitize.
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kalvado

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Re: Audiophile issues
« Reply #10 on: June 29, 2022, 11:45:40 AM »

None of my audio components have the third plug. They're only two-wire cords/plugs.

The turntable has a switchable preamp and I keep it turned off when it's plugged into the PHONO jacks. There is no hum if I turn the preamp on and plug it into the AUX port of the receiver.

I've done the jiggling/twisting thing and separated the cords as much as possible.

I really suspect the issue is the fact that the turntable doesn't have a GND connector. If the input is switched to "phono" with nothing plugged in to the PHONO RCA jacks, no hum is present. But if an RCA audio cable is plugged in to the jacks, even if it is not plugged into a component, the hum returns.

I can work around it by using the AUX port and turning the preamp on, but that eliminates an audio port. I actually have a Realistic 8-track player I'd like to connect because I have some old vintage 8-tracks I'd like to digitize.
What kind of cable are you using for the phono connection? Is it detachable from turntable? What happens if you plug that cable in and touch the turntable end?
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hbelkins

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Re: Audiophile issues
« Reply #11 on: June 30, 2022, 10:12:02 AM »

None of my audio components have the third plug. They're only two-wire cords/plugs.

The turntable has a switchable preamp and I keep it turned off when it's plugged into the PHONO jacks. There is no hum if I turn the preamp on and plug it into the AUX port of the receiver.

I've done the jiggling/twisting thing and separated the cords as much as possible.

I really suspect the issue is the fact that the turntable doesn't have a GND connector. If the input is switched to "phono" with nothing plugged in to the PHONO RCA jacks, no hum is present. But if an RCA audio cable is plugged in to the jacks, even if it is not plugged into a component, the hum returns.

I can work around it by using the AUX port and turning the preamp on, but that eliminates an audio port. I actually have a Realistic 8-track player I'd like to connect because I have some old vintage 8-tracks I'd like to digitize.
What kind of cable are you using for the phono connection? Is it detachable from turntable? What happens if you plug that cable in and touch the turntable end?

It's a standard RCA cable that is detachable on both ends. I have tried multiple RCA cables -- the one that came with the turntable and a couple I already had -- with the same result.

If I plug the cables in to the receiver and touch the other end, it will pop, crack, hum louder, or various other sound effects.
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Dirt Roads

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Re: Audiophile issues
« Reply #12 on: June 30, 2022, 11:09:34 AM »

What kind of cable are you using for the phono connection? Is it detachable from turntable? What happens if you plug that cable in and touch the turntable end?

It's a standard RCA cable that is detachable on both ends. I have tried multiple RCA cables -- the one that came with the turntable and a couple I already had -- with the same result.

If I plug the cables in to the receiver and touch the other end, it will pop, crack, hum louder, or various other sound effects.

The main difference between the PHONO jacks and the AUX jack is the signal strength.  The AUX signal is assumed to be a high-quality, high-strength audio signal that doesn't need amplification.  The PHONO signal is [correctly] assumed to be a low strength audio signal generated directly from the vibration of the grooves on the record player.  So it makes perfect sense that any noise that gets on the PHONO cables is amplified as N~O~I~S~E.  So my question is whether the turntable is generating the noise, or the RCA cables are [causing] the noise.

One of the hallmarks of a good stereo system is to use ultra-high quality RCA cables for the PHONO jacks. (I don't).  But it is possible that the jacks on one end of your RCA cables are going bad.  (Most of mine are).  But that would cause the pop and crackle.  The hum is a different story.

I usually suspect third-harmonic hums based on 60Hz power frequency:  180Hz is a very low pitched hum and 540Hz is a hum that is in the middle of the voice range (actually, quite close to the C-note in the middle of the treble clef; a little closer to the C#).  A fluorescent light fixture with a bad ballast is often the source of such hums.  But for the record, the hum from a fluorescent light fixture is almost always related to the mechanical vibrations picked up by the metal fixture or the light tubes (and resonated by the length of the vibration). 

Anyhow, the same problem can happen with the phono cartridge itself picking up vibrations caused by the power supply in the turntable.  One way to tell if your hum is getting picked up by the turntable is to plug the PHONO output from the turntable into a CD input (or AUX input) on the receiver/amp.  Crank up the volume and if the sound goes away, the issue is within the turntable itself.  Most audiophiles recommend replacing the phono cartridge with a high-quality head (uhh, I don't).  I'd be happy with pumping the PREAMP output into an AUX input, or manually swapping out the PHONO with the CD input and cranking up the volume.
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hbelkins

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Re: Audiophile issues
« Reply #13 on: July 01, 2022, 10:21:45 AM »

An update on the situation. We came across my old Technics SL-D30 turntable last night that was originally part of the system. It has a dedicated GND port and came with a grounding cable that attaches to the GND port on the receiver. I hooked it up, and the hum was not present. It still plays as good as ever. Since Victrola had already suggested sending the new one I bought back as defective, it will be going back to Amazon for a refund, especially since it's not needed.

The Technics turntable has slider controls for speed (33/45), repeat (on/off), and cueing. The slider controls were stuck in place, as there appears to be some corrosion because the turntable was stored in a trunk in a humid, not-well-ventilated room. A little WD-40 got the speed and repeat sliders moving, but I wasn't able to get the cueing slider freed. I'm going to shoot some more WD-40 to it and if that doesn't work, I'll try some penetrating oil like 3-in-1 Oil. But even if I can't get the cueing slider to work, the fully automatic turntable works fine and if I have to manually cue the tone arm if I want to start playing an album somewhere other than the beginning, I will.

It should be noted that the Victrola turntable did not hum when plugged into an AUX audio port with the switchable preamp on. Only if something was plugged into the PHONO ports was the hum present, which makes me think it was a grounding issue.

But at any rate, the problem is solved.
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bandit957

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Re: Audiophile issues
« Reply #14 on: July 01, 2022, 12:56:09 PM »

Hope you can get a stylus for it. Those are expensive.

Thirty years ago, you could buy them at Kmart for $5. Now it costs many times that, and you have to order them.
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Re: Audiophile issues
« Reply #15 on: July 01, 2022, 01:41:28 PM »

Hope you can get a stylus for it. Those are expensive.

Thirty years ago, you could buy them at Kmart for $5. Now it costs many times that, and you have to order them.
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