Phono Hum Problem Affected By Cartridge Vicinity

Hi,

My system has a phono hum in it that is particularly annoying when listening to quieter music on Vinyl.

The turntable's ground lug is firmly attached to my integrated's ground screw, though I do notice the hum gets MUCH worse when I detach it from the ground screw. Everything is plugged into the same surge protector.

The most interesting thing to me is that the severity of the hum lessens the further my phono cartridge gets from my integrated amplifier. My turntable sits to the left of my amplifier and is on the same surface. Moving the cartridge away from the amp lessens the hum a great deal. Therefore, the hum is worse at the beginning of record sides than at the end.

Has anybody experienced a hum like this before? Is there anything I can do to get rid of it without buying new furniture and rearranging so my turntable doesn't sit next to my amp?

Thanks,

Matt

 

Get it far from the amplifier. Amps have a fairly large magnetic field around them due to the rather large transformers inside of them.

I keep my amps at low level, near the floor, while the TTs are on a normal height counter top.

 

I understand that just moving the turntable and integrated amp further apart will likely solve this problem but I don't have that luxury. My integrated amp has an HT Bypass switch on the back of the unit that I need to be able to access easily multiple times per day. Therefore, it also needs to be at an easily reachable height, just like the turntable. And I only have one surface to put these things on and only about 2 inches of space between them. I do not want to buy different furniture and rearrange my room if I can help it.

What about some sort of barrier between the two? Does anybody know of some sort of material that can be mounted vertically with about two inches of horizontal space to potentially isolate the amps' magnetic field from the phono cartridge? Or is that not how this type of thing works?

 

What cartridge? What turntable? Some carts have no shielding, and can easily pick up hum, and can have increasing hum when the cart is closer to the tt motor, which could fit what you hear. One brand of turntable is infamous for its humming problems which seem to be almost a random situation with the problem being a motor with some problem, while other units of the same tt model don't have a problem.

With your tt currently to the left of the amp, you could try exchanging positions to put the tt to the right of the amp, getting the cart further from the amp.

There could be a problem with the amp.

 

Try not using the same surge strip. Please fill out in your profile the gear you are using. If proximity is the cause and you can not move further away, consider a different cartridge. I am curious why you need to use the switch on the rear of the amp so often? A barrier will not work.

 

Need more info. A recording of the "hum" would help. Gear with transformers like amps should be kept as far away from the TT as practically possible.

You can try a big piece of copper shielding if you want, no guarantee that will solve the problem though.

 

Let your turntable sit to the RIGHT of your amplifier, it will probably help a lot.

 

Swapping sides can help when the transformer in the amp is one the left side.
If you want 0 expenses, you can try to find a metal sheet, mount it vertical between the two and mount a grounding wire onto it (to power outlet ground, not the ground on your amp, since that’s signal ground).

It’ll probably be a true eyesore and the plate will be very obstructive, but it should get the job done.

 

Some responses:

The turntable is a Clearaudio Concept. The cartridge is a Hana SL. The amplifier is a Rogue Audio Cronus Magnum III.

I made a crappy recording of the hum on my iPhone.

I wish I could try swapping the positions but my Cardas speaker cables and interconnects are not long enough for that to work. It would cost me several hundred dollars to switch the positions and replace with quality equivalent cables.

I need to flip the switch on the back to engage the HT Bypass. So whenever I watch TV / Movies the switch in the back needs to be flipped up. For music, the pre-amp section of the unit is engaged by flipping the switch down.

I tried plugging the TT and amp into different outlets. The problem persisted.

Question:

Any idea where to purchase this metal/copper barrier some of you seem to be suggesting? There's no pre-cut audiophile marketed solution for this sort of thing is there?

 

That is probably magnetic induced hum from the power transformer of your integrated amp. It is possible that if you move the turntable to the right of the amp that it would get better. Copper will not shield magnetic fields, only mu-metal will. Mu-metal is hard to find in small quantites.

 

Well, if you want it cheaply, an "audiophile solution" would definitely be too expensive (audiophile is a synonym for "overpriced" in the world of marketeers and salesmen).
Just some generic zinc coated sheet of metal from a DIY shop would do I think.
A mesh with the right hole size (depends on EM frequency) would also work.

If you want 0 expenses, you can rip off the metal side panel of a trashed washing machine and cut it to the right size... but that would probably look quite funny

The turntable is 2 inches away from the amp, so that's out of reach of the magnetic field.

 

As others have noted, sounds like induced hum from amp electronics -- most probably its power transformer. The solution is going to be increasing the physical distance between the amp and the turntable. I know you don't want to spend the money for the longer Cardas cables, but it might be worth it to play with the distances using cheaper cables. Cheaper cables but less hum might in the end equal better sound than more expensive cables and noise/hum.

 

Can you put the deck on a wall shelf which will be above and away from the amp.

Some photos of the present set up would be good.

 

Do as @Jimi Floyd and @chervokas suggest. You'll get better sound and save money.
-Bill

 

Try this, go to any place that sells cheap cables. Buy a long pair for as little as you can. Say 6-8-10 feet. Try one. see if moving it solves the issue. If it does then you know what needs to be done and you can move on to how to do it. Get past R & D and into Engineering the solution. If you can not move the TT can you move the amp? Even a few feet may do it.

 

Sorry for coming to this rather late. Based on my similar experience, the cause is almost certainly the power transformer in the amplifier. If you can't move the amp, I suggest you remove the transformer from the amp and move it to a suitable remote location (leaving the amp where it is). Reconnect it using multi-core mains cable (I bought this from ebay). I did this with the transformers on my phono-amp and headphone-amp. This eliminated the hums and enabled me to achieve a zero noise floor for the whole system, which would otherwise have been impossible. Total cost less than £20. The transformers are in a cupboard about 4ft away from the phono stage and turntable.

 

Distance is your friend when it comes to low frequency magnetic fields: http://www.hagtech.com/pdf/eliminatingnoise.pdf

And the field may be coming from the TT motor, not the receiver? If so, check this out: Humbucker

 

Hi Jim
Your eliminating-noise document is spot-on. I wish I had seen it before starting my noise-elimination journey.

It addresses noise generated by the audio set-up, which leaves the noise generated by and within the components themselves. Transformers are the main culprit, especially the big square ones favoured by the manufacturers of valve/tube based equipment. Toroidals are far less of a problem. Why the square transformers are still used on front-end equipment such as phono stages is a mystery to me.

Electrical interference from mains cables, etc is easy to screen and an inch or two of separation will eliminate it. Magnetic fields, however, are difficult to screen and require much greater separation of components. In my opinion, removing transformers from sensitive equipment such as phono stages is the only way to achieve audio perfection. I imagine this is why high-end equipment often has a separate power supply but people normally put the power supply next to the equipment, which rather defeats the object.

Chris

 

The standard EI laminated core transformers are generally cheaper, but they also have a magnetic gap in the core so aren't as susceptible to mechanical hum from the type of AC line distortion that results in a DC component. Toroidal transformers don't normally have an air gap in the core, which makes them more efficient, but any DC on the line can saturate the core and cause vibration. In today's world of dirty power, I think this is one of the main reasons a lot of audio manufacturers shy away from them.

The other big difference is in high frequency rejection. Toroidal transformers have a much wider bandwidth than the standard EI types, and higher capacitive coupling between the primary and secondary since they are generally wound on top of each other. The better EI transformers are wound with separate primary and secondary bobbins, so can be made with very high isolation. There are some newer designs for toroids, such as NBT (narrow band technology), that can help with the bandwidth issue, and so don't require as much HF filtering on the primary side.

 

Thank you for your detailed reply - you clearly know a lot more about transformers than me. May I ask you a question that has puzzled me?

Towards the end of my noise-elimination journey, I took an old 750Watt Regulac autotransformer (the British version of the Variac), which I had in my workshop, and plugged it into the mains feed to my phono stage at equal voltages (230V in 230V out). Hum had already been eliminated by moving the transformers and the Regulac removed almost all of the remaining random noise, such that the system is silent even with the volume knob well above my normal listening volume. It is now part of my set-up.

The effect is real but I cannot explain it. I'd very much appreciate your thoughts.

 

Like a regular transformer, there will be some noise immunity due to the bandwidth limitation of power transformers. You still have the core and the winding inductance, you just don't get any isolation since there is only one winding on an autotransformer. So it's not surprising that some line noise is reduced, though it's much more effective to use a good isolation transformer and input filter with high quality noise suppression capacitors.

 

Thank you, once again. Much appreciated. I think I will stay with the Regulac for the time being as it does the job. "If it ain't broke, don't fix it".

 

Just to update everybody on my situation: My amplifier stopped turning on a couple months ago and Nick at Rogue was quick to identify the problem as a failed bridge rectifier. He sent me a new one and I installed it in the amplifier. I put the amplifier back in the same position and much to my surprise the hum was now gone.

I still don't know if it was actually the faulty part that was causing the hum or if just me jostling every thing around while I was making the repair had some influence but, hey, I'm not gonna complain. It all worked out.

 

I just had this problem this week and solved it after reading this thread yesterday.

over the weekend I decided to change the cabinet that my components were on. Originally my integrated amp was located on the top left with my turntable in the middle, CD player on the right. My streamer was on a lower shelf. No issues with phono hum in this set up.

Once I swapped out the cabinet I decided that I wanted my amp in the middle of the shelf with the turntable next to it on the left. When I turned my system on to play some vinyl, zing! Phono hum!

This morning I swapped components, turntable on the right end of the shelf, amplifier on the left end of the shelf with the CD player smack dab in the middle of the two. Viola! No hum!

Thank you to all who suggested putting some space between the amp and turntable. That works!