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Turntable hum from RCA cables.

post #1 of 25
Thread Starter 
Searched everywhere but couldn't find an answer that worked for my exact issue.

First, the gear:

Pro-Ject Debut III TT - Stock
Pro-Ject Phono Box II
Pioneer Elite - VSX-21TXH Receiver
Audioquest Sidewinder interconnects from the Pre-Amp to the receiver.

The Problem - Hum:

There is a hum in the system which seems to be caused by the RCA cables, mostly the right channel, to the pre-amp. When I touch it, the hum increases. I have found what seems to help, but not eliminate the hum, is to raise the pre-amp straight above the TT as far as the cables allow. It seems to be only vertically, not if I stretch it side to side, maybe because side to side makes the cables touch each other and the ground more.

I have the ground from the TT to the pre-amp, and have tried my Panamax power conditioner with no change. Both the TT and pre-amp are plugged into the same outlet. I've wrapped the cable in aluminum foil but hear little if any difference but I plan to try again with multiple layers on both cables. Also tried flipping the power blocks for both the TT and pre-amp in each socket up-side-down, no change. Also, I have tried best to keep the interconnects from crossing any of the power cables, have when moved close to them I noticed they do make the hum louder.

I think I've covered everything, any ideas? I'd love to just swap the RCA cables but they are hard-wired to the turntable.

Thanks,
Tim
post #2 of 25
Try hooking your turntable up to another source such as a different amplifier or receiver. I found that the problem was with my receiver and not my turntable when I did this. You might be having the same problem as I did.
post #3 of 25
If you have spare RCA cable 6-10 feet long, try connect it to preamp instead of TT. If you hear significant hum in this case, then most likely problem is power supply in your preamp. If hum is very low, then either TT's power supply or TT's cable has problem.
post #4 of 25
The moving around bit strongly suggests a cable problem. Try connecting the turntable to something else. Try switching the right and left channels, and see if the hum changes channels, too.

If it's the cable, it's likely to be the connectors. So you could just snip them off and re-terminate, before you go to the trouble of replacing the whole cable.
post #5 of 25
The hum is coming from the transformer(s). Their magnetic field induces current in MM cartridge.

Move away the turntable from all other Hi-Fi components.

Almost all amps and pre-amps have the mains transformers located at the left of the unit (inside). Placing the turntable to the right of amps and pre-amps usually fixes the problem.

Some British gear have transformers on the right side, so I suggest you check visually and locate the transformers and then move the cartridge as far away as possible (interconnections length’ permitting) from source of magnetic radiation.

Let me know if this fixed the problem…

Boky
post #6 of 25
I used to get a hum that went away when I unhooked the ground from turntable to AVR.
post #7 of 25
Thread Starter 
So it's been a while but this is what I have tried or forgot to mention:

Hum only exists when the TT is plugged into the pre-amp but it exists when the TT is on and off, including unplugged from the outlet.

Swapped directions of the RCA cables from the preamp to receiver and tried different calbes, no change.

Switch the R/W from TT at preamp and the hum follows the red rca. If I unplug the red and touch it to the ground on the preamp there is no hum, so would it be a good idea to somehow connect the red rca to the ground when it is plugged in?

The biggest effect on the level of hum is handling it. Extremely loud if I wrap my whole hand around it.
post #8 of 25
It sounds like the red cable is shorting out. Can you unscrew the covering and check the wire? It seems like the solder broke or there is a loose connection.
post #9 of 25
That's ground loop. Instead of grounding to your amp, run the turntable ground wire to the screw in the middle of the faceplate on the power receptacle in the wall. If your house is up to code, that should fix it.
post #10 of 25
Thread Starter 
Quote:
Originally Posted by Kensmith48 View Post

It sounds like the red cable is shorting out. Can you unscrew the covering and check the wire? It seems like the solder broke or there is a loose connection.

Hard to say, not really sure what I'm looking for.

Here is a picture I took, hard to get a good picture.
post #11 of 25
Thread Starter 
Quote:
Originally Posted by sworth View Post

That's ground loop. Instead of grounding to your amp, run the turntable ground wire to the screw in the middle of the faceplate on the power receptacle in the wall. If your house is up to code, that should fix it.

Tried that, same amount of hum as grounding to pre-amp or any other thing I've grounded to.
post #12 of 25
Quote:
Originally Posted by TSuellentrop View Post

Hard to say, not really sure what I'm looking for.

Here is a picture I took, hard to get a good picture.

I thought that you were refering to a seperate audio cable with rca's on each end.
The only thing I see in your picture that might be a problem is the red wire on the right. If the exposed copper is touching metal it could create a short. I'd put a piece of electrical tape on the exposed section. Otherwise the solder connections look good.
post #13 of 25
Quote:
Originally Posted by TSuellentrop View Post

Hard to say, not really sure what I'm looking for.

Here is a picture I took, hard to get a good picture.

From that picture it does not look like a professional soldering job. Was it DIY? If not, I would expect that there are other problems.
post #14 of 25
Thread Starter 
Quote:
Originally Posted by ap1 View Post

From that picture it does not look like a professional soldering job. Was it DIY? If not, I would expect that there are other problems.

Nope, stock from the factory.
post #15 of 25
Quote:
Originally Posted by TSuellentrop View Post

Nope, stock from the factory.

Looks like manufacturers do not care about quality anymore. I would try to send TT for repair under warranty.
post #16 of 25
New.turntables suck. For the same price as an entry level new model, you can get a 70s Dual direct drive or Thorens belt drive that perform on the level of high end models. See if you can get a refund and look for used. The Dual 1218/1219, 1018/1019 or Thorens TD160 or 165 are terrific tables for a bargain price.
post #17 of 25
Argh... come on, poor soldering, warranty service, new turntables suck... Tables just hum sometimes for a number of reasons.

OP, be sure you are wired correctly at the cartridge. If you have a meter, you can test your wiring.

red=right +
white=left +
green=right -
blue=left -

Then, what happens to the hum if you don't connect the table ground to anything?

If that doesn't help, then you got to solve the problem by getting back to basics.

Unplug EVERYTHING except the table, phono and receiver and see if the hum goes away. That means unplug everything unnecessary from the receiver AND unplug everything from the wall. Does it hum? If not, then start plugging things back one at a time to find the culprit.

[EDIT] DO NOT put a meter to your cartridge! Under the right circumstances i.e. low output MC, older meter with higher voltage, you can damage the cartridge coils. I suspect that would not happen, but worth mentioning and not worth risking.
post #18 of 25
Hey sorry to be asking for this here, but I didn't want to start a new thread just for this.

Where can get wire/cable for a Turn Table? I've Google it and I fine ridicules priced ones with some odd plug either for the Arm, or nothing at all..

They would need to be longer than the 1 meter that seem to come with all TT? Which I don't get why do they come so short in the first place!

So at least over 2.5 meters or over so if I feel like putting my TT on the other side of my living room if I wanted to.

Thanks

Djoel
post #19 of 25
If you're going to use long cables, add them AFTER the phono preamp, not before. Line level will travel further than the low level output from a turntable.

You want a pair of female RCA to male RCA. You can get them at Radio Shack.
post #20 of 25
Quote:
Originally Posted by sworth View Post

If you're going to use long cables, add them AFTER the phono preamp, not before. Line level will travel further than the low level output from a turntable.

You want a pair of female RCA to male RCA. You can get them at Radio Shack.


If you're replying to my post about the longer phono cables.

Thanks, any cables will do then. should I avoid ground single wire?

Also, you sounds serious about adding the cables to the table after it goes in to the Phono Preamp. Why? I can make a guess, but I don't want to assume.

Djoel
post #21 of 25
Thread Starter 
UPDATE:

I have since moved to a Marantz PM5004 with a phono stage built in and have lowered but not solved the hum issue. It is still fairly audible and can get very loud with the volume turned up. The RCAs go directly into the 5004 with the ground the same.
post #22 of 25
U must have an high-voltage tower nearby.

Or there is an old step-down transformer right outside. I know that during my commute, there is this residential spot, pretty wide open, no overhead walkway nothing, but every time I go through it, my AM goes bananas.
post #23 of 25
Quote:
Originally Posted by Extreme_Boky View Post

The hum is coming from the transformer(s). Their magnetic field induces current in MM cartridge.

Move away the turntable from all other Hi-Fi components.

Almost all amps and pre-amps have the mains transformers located at the left of the unit (inside). Placing the turntable to the right of amps and pre-amps usually fixes the problem.

Some British gear have transformers on the right side, so I suggest you check visually and locate the transformers and then move the cartridge as far away as possible (interconnections length’ permitting) from source of magnetic radiation.

Let me know if this fixed the problem…

Boky

Wow!  Simply moving my old TT to the right of my Rotel receiver appears to have cured my years long annoying hum problem.  Thanks, Boky!

post #24 of 25
The turntable should really be located at least two feet from any sort of power transformer.

Some high-quality equipment that has excellent chassis construction and shielding might be OK closer, but don't count on it.

The output of MC cartridges is so tiny that it makes it a problem at times.
post #25 of 25
Check Audioquest cables at Needle Doctor or Music Direct.

Try to limit them to 2 meters if possible. Longer ones makes hum problems possible.

If you need the turntable that far from the amplifier, run short cables to the phono preamp module and then longer ones from it to the amplifier/receiver.

Quote:
Originally Posted by Djoel View Post

Hey sorry to be asking for this here, but I didn't want to start a new thread just for this.


Where can get wire/cable for a Turn Table? I've Google it and I fine ridicules priced ones with some odd plug either for the Arm, or nothing at all..


They would need to be longer than the 1 meter that seem to come with all TT? Which I don't get why do they come so short in the first place!


So at least over 2.5 meters or over so if I feel like putting my TT on the other side of my living room if I wanted to.


Thanks


Djoel
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