electrical engineer needed

[rocknroll1]

So I have a hum thru my speakers that only comes when phono input is selected. Its has to be coming from the TT (empire 698) because I tried another TT and no hum and then I tried the 698 on another receiver and it is there. First I tried another head shell and cart, then replaced output cables, replace the body ground wires, cleaned all connectors and don't know what else to check. The tonearm wires run thru the tonearm and out to the connectors that I cleaned. I even ran a extension cord in to try another plug. Two things that I notice were it still makes the noise with the TT off and receiver on and it goes away when I remove the TT ground wire from the ground on back of receiver (tt on or off). The hum does not affect listening because you only notice it between tracks or at the end run off. The hum goes up with the volume. HELP!!!

 

[phantomrebel]

Sounds like a classic ground loop to me, though I'm no EE. If it goes away when you disconnect the TT ground from the receiver, why not just leave it off (problem solved)?

 

[bobins08]

Ground loop.

The grounding scheme is wrong in some way. Did you change anything?

Is the table already grounded through your rca shields? If so and you add a ground wire you may be causing they problem.

 

[Doug G.]

If a metal cartridge body is grounded to the headshell and the headshell is grounded to the arm and the arm is grounded to the chassis and one of the cartridge ground pins is grounded to the cartridge, you have a ground loop. The cartridge body MUST be isolated from the metal turntable structures (headshell, arm, etc.). Also, the things the other guys said above.

Doug

 

[rocknroll1]

Ground loop.

The grounding scheme is wrong in some way. Did you change anything?

Is the table already grounded through your rca shields? If so and you add a ground wire you may be causing they problem.

I have note changed anything but i think it started after i trashed my needle when I knocked my tone arm off it's rest while adjusting the height of the arm. I say think because I had to switch TTs after that. How do find the culprit and fix a ground loop? can I disconnect the ground as bobins08 mentioned?

 

[rocknroll1]

If a metal cartridge body is grounded to the headshell and the headshell is grounded to the arm and the arm is grounded to the chassis and one of the cartridge ground pins is grounded to the cartridge, you have a ground loop. The cartridge body MUST be isolated from the metal turntable structures (headshell, arm, etc.). Also, the things the other guys said above.

Doug

That helps a lot. It is a medal headshell and cart. I did use the nylon screws but not the plastic adapter that came with cart.I will add the adapter and see if that fixes it.

 

[bobins08]

When you knocked the tone arm off the rest did the head shell wires to the cartridge connector pins get jostled? Check them and make sure they are correctly installed and that they are gripping the cartridge pins (not loose).

If that des not help try playing it with and without the ground wire attached.

If no help there then follow the procedure Doug posted. You will need an ohm meter to do that.

 

[rocknroll1]

That helps a lot. It is a medal headshell and cart. I did use the nylon screws but not the plastic adapter that came with cart.I will add the adapter and see if that fixes it.

But now that I think about it the 2nd headshell was medal but plastic cart. I still am going to try adapter.

 

[rocknroll1]

If a metal cartridge body is grounded to the headshell and the headshell is grounded to the arm and the arm is grounded to the chassis and one of the cartridge ground pins is grounded to the cartridge, you have a ground loop. The cartridge body MUST be isolated from the metal turntable structures (headshell, arm, etc.). Also, the things the other guys said above.

Doug it is as you said with the exception of the nylon screws I used, medal everywhere.

 

[rocknroll1]

Ok I tried putting plastic spacer between cart body and headshell but no help. as a matter of fact it still humid without headshell attached. What did help is removing ground wire from receiver and placing it on the 3rd ground prong of another component plugged in to a extension strip. Will this harm anything playing it that way? Or does this reveal anything else?

 

[Jeffery]

Do you have any pics of the tonearm? The reason I ask is because you mention trying a different headshell, and the 698 headshell is a unique design that's only used on that particular arm. If your 698 has a different tonearm, then a simple grounding error would be easy to trace out.

 

[empirelvr]

We need to establish a baseline to try and find out what the problem is. A big help will be to fill out your equipment list in your profile. That way we won't have to ask the same gear questions over and over. Any one of us can look at what gear you have and see if we can tell anything from there. Include video gear. You may have mentioned what associated gear you are using, but trying to go through numerous posts can be a time waster.

Now, part 2: a good way to help you right now is to answer these questions, no matter how far from your problem it may seem. Knowing this information will help give a clearer picture.

1. What cartridge are you using?

2. If the body of the cartridge is metal, is the little copper ground strap that is attached to one of the ground pins present?

2. Are all the plugs from your various pieces of equipment (receiver, TT, tape deck, etc) all going to one power strip/surge protector or are they plugged into various wall outlets in your listening space?

3. Do any of your components have a 3 pronged electrical cord?

4. Do you have a cable TV or TV satellite box audio, or any kind of video based piece of gear that may be connected to a cable box or satellite box connected to your system?

5. The 698's power cord plug is not polarized so it will fit either way into an outlet. (https://blog.1000bulbs.com/home/polarized-vs-non-polarized-electrical-plugs) This has a big influence on hum. Have you tried switching the plug to see if the hum level goes up or down? Is the ground wire beneath the unit that attaches to a tab on the motor still attached?

6. Did you check the area where the headshell mates with the tonearm to make sure the tabs have not bent out of shape and are okay?

 

[boreas]

Ok I tried putting plastic spacer between cart body and headshell but no help. as a matter of fact it still humid without headshell attached. What did help is removing ground wire from receiver and placing it on the 3rd ground prong of another component plugged in to a extension strip. Will this harm anything playing it that way? Or does this reveal anything else?

Okay, you can forget the headshell and cartridge as the source of the problem. The problem is a short in the tonearm or RCA cables. Since you say that you jostled the tonearm, the first place I'd look is the tonearm wires where they exit the tonearm.

John

 

[rocknroll1]

We need to establish a baseline to try and find out what the problem is. A big help will be to fill out your equipment list in your profile. That way we won't have to ask the same gear questions over and over. Any one of us can look at what gear you have and see if we can tell anything from there. Include video gear. You may have mentioned what associated gear you are using, but trying to go through numerous posts can be a time waster.

Now, part 2: a good way to help you right now is to answer these questions, no matter how far from your problem it may seem. Knowing this information will help give a clearer picture.

1. What cartridge are you using?

2. If the body of the cartridge is metal, is the little copper ground strap that is attached to one of the ground pins present?

2. Are all the plugs from your various pieces of equipment (receiver, TT, tape deck, etc) all going to one power strip/surge protector or are they plugged into various wall outlets in your listening space?

3. Do any of your components have a 3 pronged electrical cord?

4. Do you have a cable TV or TV satellite box audio, or any kind of video based piece of gear that may be connected to a cable box or satellite box connected to your system?

5. The 698's power cord plug is not polarized so it will fit either way into an outlet. (https://blog.1000bulbs.com/home/polarized-vs-non-polarized-electrical-plugs) This has a big influence on hum. Have you tried switching the plug to see if the hum level goes up or down? Is the ground wire beneath the unit that attaches to a tab on the motor still attached?

6. Did you check the area where the headshell mates with the tonearm to make sure the tabs have not bent out of shape and are okay?

will fill out profile page but for now the system is a marantz 2275 recapped and serviced 4 years ago, empire 698 w/2000e/III cart and stylus NOS 5 hours on it (also tried fairly new grado cart and stylus) with heresey II speakers.
1. 2000E/111
2. Yes and Yes
2.TT into wall and receiver, DAC (maverick D2) and CDP into strip which is plugged into same wall socket as TT. Sidenote; I ran a long extension cord from another room and tried TT by itself with no change. Also as stated above I removed ground wire from receiver and grounded it to the ground prong of one of the 3 pronged plugs in the strip and hum is gone. Will cause any damage to either unit?
3.all but TT and receiver are 3 prong
4. No all audio
5.No not on purpose but as many times as I have plugged and unplugged it Ii am sure it has been done. Yes I replaced it with a copper wire because old one was brittle. It runs from motor housing to screw in wood frame with 2nd wire from frame to bolt in medal carriage.
6. yes and I clean them with DE-oxit and cu-tip.
Also I reported above that it hums with power off on TT if that helps

 

[rocknroll1]

Do you have any pics of the tonearm? The reason I ask is because you mention trying a different headshell, and the 698 headshell is a unique design that's only used on that particular arm. If your 698 has a different tonearm, then a simple grounding error would be easy to trace out.

It is the correct arm, I just happen to have 2 of the correct headshells

 

[rocknroll1]

Okay, you can forget the headshell and cartridge as the source of the problem. The problem is a short in the tonearm or RCA cables. Since you say that you jostled the tonearm, the first place I'd look is the tonearm wires where they exit the tonearm.

John

the wires run into a clip that plugs in, I checked all wires and they seemed snug and then I sprayed De-oxit into it. As far as the other end of the wires at end of tonearm, I am not sure how to check them.

 

[empirelvr]

2. Yes and Yes

Good.

2.TT into wall and receiver, DAC (maverick D2) and CDP into strip which is plugged into same wall socket as TT.

Also good, although I'd try to get everything plugged into one power stip/surge suppressor if possible. Just for saftey's sake.

...Also as stated above I removed ground wire from receiver and grounded it to the ground prong of one of the 3 pronged plugs in the strip and hum is gone. Will cause any damage to either unit?

No damage will result, and in fact this presents a clue as to what might be going on.

3.all but TT and receiver are 3 prong

I knew it.

5.No not on purpose but as many times as I have plugged and unplugged it Ii am sure it has been done.

We will get back to this after you try what I'm outlining below.

Sounds like you have a classic ground loop caused by one and/or both of the pieces of gear with 3-prong plugs.

How to prove it: Ground the tonearm cable back to the Marantz ground post. Disconnect the power cords of the DAC and CDP (which I assume are the ones with 3 prong plugs?), leave the audio cables from these devices connected to the Marantz. Turn on the Marantz and 698 and listen. Is hum there? If so, you might need to remove the copper tab off the ground terminal of the 2000E/III cart. (I don't think you will though.)

If there isn't any hum (which is what I suspect you'll find,) lower volume and plug ONE of the 3 prong cords into the strip. Keep unit turned off. Make note of either presence of hum or it's absence and then turn on the component. After the test, unplug that 3 prong cable. Then plug in second 3 pronged AC cable and make a note of the absence or presence of hum with unit off then on as above. Then plug both in. Check for hum first with both units off, then turn them on one at a time, always checking for the hum. Make note of findings.

What I strongly suspect is you have a ground loop caused by the two components that have the 3 pronged AC cable. The clue for me is that connecting the 698's ground wire to the outlet ground makes things silent which means by grounding it to the outlet ground, you are breaking the loop and proper grounding is restored.

Ground loops like this can be tricky. I outlined the troubleshooting steps above because we have to determine if it is the DAC, the CDP, or a combination of both that is the culprit. If you get hum with one plugged in without the other, when you plug in both, is the hum the same, or louder?

Try that and report back. We're not finished yet, but we need the results of this test first to determine the next steps.

 

[rocknroll1]

Good.

Also good, although I'd try to get everything plugged into one power stip/surge suppressor if possible. Just for saftey's sake.

No damage will result, and in fact this presents a clue as to what might be going on.

I knew it.

We will get back to this after you try what I'm outlining below.

Sounds like you have a classic ground loop caused by one and/or both of the pieces of gear with 3-prong plugs.

How to prove it: Ground the tonearm cable back to the Marantz ground post. Disconnect the power cords of the DAC and CDP (which I assume are the ones with 3 prong plugs?), leave the audio cables from these devices connected to the Marantz. Turn on the Marantz and 698 and listen. Is hum there? If so, you might need to remove the copper tab off the ground terminal of the 2000E/III cart. (I don't think you will though.)

If there isn't any hum (which is what I suspect you'll find,) lower volume and plug ONE of the 3 prong cords into the strip. Keep unit turned off. Make note of either presence of hum or it's absence and then turn on the component. After the test, unplug that 3 prong cable. Then plug in second 3 pronged AC cable and make a note of the absence or presence of hum with unit off then on as above. Then plug both in. Check for hum first with both units off, then turn them on one at a time, always checking for the hum. Make note of findings.

What I strongly suspect is you have a ground loop caused by the two components that have the 3 pronged AC cable. The clue for me is that connecting the 698's ground wire to the outlet ground makes things silent which means by grounding it to the outlet ground, you are breaking the loop and proper grounding is restored.

Ground loops like this can be tricky. I outlined the troubleshooting steps above because we have to determine if it is the DAC, the CDP, or a combination of both that is the culprit. If you get hum with one plugged in without the other, when you plug in both, is the hum the same, or louder?

Try that and report back. We're not finished yet, but we need the results of this test first to determine the next steps.

put ground wire back on marantz and unplugged CDP and DAC (both marantz and TT in power strip same hum. introduced other components one at a time and still get hum. Then tried another power strip just to make sure got same hum. With the different test above I tried it with and without TT on and it made no difference. After this test I put ground back 3 prong DAC and hum isn't completely gone put have to get almost to 12 o'clock position on volume until you hear it. I am sure thats the way it ways before.

 

[rocknroll1]

If it makes any difference TT is on a shelf about 5 inches above Marantz in a cabinet with speakers about 2.5' away on each side. Other components are about 2' above TT in another cabinet. TT motor makes a slight noise but you can't hear it from 2' away, you have to be right on it.

 

[empirelvr]

put ground wire back on marantz and unplugged CDP and DAC (both marantz and TT in power strip same hum. introduced other components one at a time and still get hum. Then tried another power strip just to make sure got same hum. With the different test above I tried it with and without TT on and it made no difference. After this test I put ground back 3 prong DAC and hum isn't completely gone put have to get almost to 12 o'clock position on volume until you hear it. I am sure thats the way it ways before.

Okay, so you have hum when there's nothing but the TT and Marantz plugged into the power strip. That would rule out a ground loop sourced from the grounded components. Our next is to try removing the ground strap from the cartridge. Since the cartridge body, clip, and headshell are metal, that might be what's giving you hum. Even if you are using the plastic spacers and nylon screws, that's no assurance there still isn't metal to metal contact somewhere. It's best to remove the strap with a pin or toothpick, as you want to remove it, but keep it so you can replace it if it doesn't work.

So, now do this. Disconnect the DAC and CDP's power cords from the power strip. Keep the 698's output and ground cable connected to the Marantz. Remove the headshell from the 698 and pry off the ground strap from the 2000E/III and put the headshell back on the 698. Turn on Marantz and listen for hum. If there is no hum, try plugging in the CDP and DAC's power cords one by one in the power strip. If there is still no hum, congrats, you did it. If hum comes back, there are more steps to try.