PV5 Phono Stage Hum

[skipper356]

Hi All,
I have a PV5 that I have had for several years. It now started to have a hum in both channels of the phono stage. If I remove the phono input cables the hum goes away. Adding or removing the turntable grounding strap does not seem to make a different. The hum seems to only happen when I connect the turntable. I just recently hooked up my turn table and so I had not noticed any hum until now. It seems to be a grounding loop? is there a certain impedance the input cables should have for the phono? Should the turn table be ground to the amplifier or to the preamp?

Thanks,
skipper

[admin]

First, welcome to the site. Great to have you with us.

A ground loop should be a 60 hz hum. You can also test that with a ground loop isolator RCA plug,... which can be gotten from Amazon for about $10 and is a good diagnostic tool to have.

This may be a ground loop issue, but it could also be an issue with the turntable. Do you have another turntable you can attach to make sure the fault is not in the turntable? You need to check all the wires coming from the cartridge to make sure they are connected properly and don't have any continuity damage.

[roberto]

Good points Admin,
Also route or address the TT RCAs cable in a such way that it does not touch any AC cable or even be adjacent to any other cable. The TT cable should be alone from the TT to the PV5.

Because we do like neat look of our system, we address all the cable. Sometimes we put AC cable next to RCAs cable. Avoid this! All audio cable could be together and all AC power cable could be together, but never an audio cable with a power AC cable. Even being close by one inch, the hum might be present. Sometimes to have a neat look, we make nuts of cable or address them together. In my experience, I do believe that this is your problem.

This is a must if you want to get rid of a hum.

Happy listening!

[roberto]

Skeeper356,

Please send us pics of your system installation. Show how the cable are addressed. Also, the TT could be picking a power transformer EMI (electromechanical induction). All transformers are culprit to radiate EMI. Just placing the TT away from that power transformer or routing the cable away, you could get rid of the hum.


Happy listening!

[roberto]

Separation of power and signal cables, as well as use of twisted pair cables and reduced cable length, can cut wire and cable contribution to EMI. Many other cable and wire integration and installation techniques can be used to reduce EMI.

[roberto]

Skeeper356,

I found this for you...here are tips of how to get rid of a turntable hum.
http://best-turntables.com/how-to-fix-turntable-hu/

[skipper356]

Guys thanks for the welcome and the many responses.
I am attaching some pictures but I am almost embarrassed to send them. Because of covid I moved my equipment to my make shift office. My rig is positioned haphazardly, I am going to build a stand. I got to admit that the cables are pretty junky, cheap mono-price cables.
I do have all the amp, preamp, tuner, turntable and tape deck plugged into the same power strip. I read that plugging in different outlets can cause a grounding loop.
My turn table is a Denon model DP-45f and it uses a Micro-Acoustics 2002e phono cartridge. All the wires to the cartridge seem to be connected correctly.
I do have another turn table I can try, I believe it has a MM cartridge.
One think I noticed is when I had this same set up in my living room (stacked up on a stand) and connected to my old Sansui SP-2500 speakers, when I listened to LP or anything, the gain on the preamp was large. I could only turn the volume on the preamp 5% and I was really loud. Now I am using some Polk Audio Reference Monitors 5JR and I really have to turn up the volume on the preamp. I believe they are suppose to be 93% efficient? My old Sansuis sound alot nicer.
I am going to purchase the gound loop detector RCA cable that was recommended.

thanks again
skipper

[admin]

Nice little system you got there,... nothing to be embarrassed about. COVID has interfered with lots of people's lives so I don't think this is uncommon.

I think the ground loop isolate can really help you here to eliminate the possibility of a ground loop issue so report back when you get that.

BTW, I own those exact monoprice cables. They look and feel good, but unfortunately the are terrible for the sound. I found this out the hard way. If you are looking for some good but inexpensive cables, I recommend Blue Jeans Cables or Signal Cable. You will be amazed at the improvement in sound (I was).

[skipper356]

Thanks for the links, it is time to upgrade my cables. Should I be looking for certain phono cables or are the standard RCA cables OK?

[admin]

If you want to replace the phono cable, then that is something specific as the termination on the cartridge side are not RCA.

[skipper356]

Currently my turn table cable does not reach my CJ preamp. I had to add a extension cable to reach. I was referring to the extension cable but perhaps I should make room to move the preamp close enough to the TT so that I do not need an extension cable.

[admin]

You don't want long cables unless absolutely necessary. That could be picking up interference. Especially a phono cable as the signal is already much lower than line level.

[roberto]

Admin is right. Don't use long runs, unless you have to...the signal is 1000 times smaller than the line level. Yes, 1000!!! A reason why is so sensible to pick hum or EMI.

Happy listening!

[skipper356]

Hi All,
I removed the phono cable extension and the hum is gone. I did realize how sensitive this cable is but now my CJ PV5 phono stage is quiet. I am back to playing LPs.

Cheers,
skipper

[roberto]

Good to know...

As our dear friend RJ says: enjoy those fine tunes!

Happy listening!

[admin]

Great to hear that it was a simple (and inexpensive) solution. Enjoy the music.

[roberto]

Thinking about the hum, the adaptors to extend the RCA cable is the culprit. Poor contact there. Clean very well the ground and also, to have a super tight connection.

Try it, you might get lucky.

Happy listening!
.

[Capt.Willard]

It appears you have the right channels and the left channels on several pairs of wires/components feeding into the preamp inputs reversed with no real order to them?
Traditionally the red cables (right Channel) are on the bottom row and the white or black sides (left channel) on the top row.
This might not be the phono problem but keeping it consistant overall is bound to help with the sound overall.

[roberto]

Great observation Capt.Williard,

You should use the rule: Red is right, and the black or white is left. This should be kept also in the amplifier input. Red is right! If you listen to classical music, the virtual stage from your system is usually this way: violins and violas are located at the left of the stage. In the center the brass section and at the right, the cellos and double bass. The percussion is at the back of the stage. The main instrument or voice, is dead front center. If you have wrong the input channels, the violins might sound at the right of the stage, and this is odd...the position of the symphonic orchestra is as I explained. Conrad Johnson has an incredible stage presentation. If you don't have a good stage, you should re-position your speakers to have this stage.

Happy listening!