Help with Low Level hum in phono

Problem solved.

Someone on another thread had the same problem. The nearby stacked amp was causing the hum through some sort of inductance.

So similarly, I put about 15" between amp and pre-amp and voila...the hum is gone.

Generally I'd suggest you check the routing of your cables as well. Make sure signal wires are not near AC wires, especially the wire from the tonearm to the phono pre.

Enjoy,
Bob

Ptmconsulting,

Got it covered. Thanks.

I'm thinking the problem I had here could be a common occurrence with many so I wanted to provide some more info here in case it might help someone.

I was picking up a low level buzz/hum on my phono despite the fact that everything appeared grounded properly. I only noticed it recently after moving a larger pair of full range speakers into a relatively small listening room.

The problem was the pre-amp was sitting directly on top of a new/different amp that I had put in the system a few months back and the proximity of the amp was producing some sort of inductance issue with the phono section in the preamp that caused the noticeable low level hum/buzz at higher volume settings.

I only noticed the problem when music was not playing and the volume was up, but I suspect it negatively impacted the sound quality when playing as well when occurring even though it was not directly audible because I thought I had noticed a difference in the sound of the phono since replacing the amp, which improved the sound overall in most in every other way.

The solution was to separate the amp from pre-amp by 15" or so.

Just something to keep in mind perhaps should a similar problem ever arise. I suspect it could happen with almost any amp/phono preamp closely located together except perhaps with very top line preamps with exceptional casing build.

In the case of my Carver pre-amp with built in phono section, its built like a very sturdy jeep perhaps but not like a tank as are some higher end pieces.

One other thing of note is that I believe the inductance issue the amp was creating with the pre-amp due to being stacked directly on top was affecting the sound negatively with all sources, not just phono, which is where it was most evident by the low level hum with the phono section.

Everything sounds much cleaner and more detailed now regardless of source since I put some distance between amp and pre-amp.

My suggestion would be for anyone who has an amp stacked within 12-15" of a pre-amp to consider separating them further and see if there is a difference in sound even if there is no clear audible effect.

I learned a good lesson from this and am now considering beefing up my physical location of components to put more distance between each just as a safeguard.

This experience makes me more cautious regarding receiver and integrated amp designs than I had been prior. There can clearly be issues locating other electronics near high performance power amps that have to be addressed effectively in integrated designs. The impact to the sound may not be clearly audible untill the proximity issues is addressed, which cannot be achieved through physical separation of individual component circuits in an integrated design as can be with separates. The cost of building the integrated in a manner that properly addresses this must be relatively expensive I would think compared to the simpler solution of just providing adequate distance between separate components as needed. Even with separates though, build quality could be a big factor as well in regards to how close pieces might be placed to each other safely without sonic impact, but the safe thing to do is probably to just keep things well apart if at all possible.