Low level buzz?

Audio Components
1

I’ll start by saying that the buzz is not audible except at 3 o’clock or higher on the preamp volume control (loudest I ever play is around 11 o’clock); so, if I never solve this “problem” I’ll live. But…

My preamp (Cary SLP-05) is silent. With the volume at maximum, there’s nary a peep from the preamp with the input selector on an empty input.

I hear the buzz only when selecting the DSD (balanced input), or the Sutherland phono preamp (single ended input). I get hiss from my R2R recorders, but no buzz (balanced input). The R2R is powered from a PP5.

All three components – the Cary, the DSD, and the Sutherland are powered from a PP3; however, the PP3 is NOT the problem since this buzz was there through various power arrangements – including PP5 power.

The phono pre (Sutherland) is properly grounded (turntable and cartridge ground tied to a step-up transformer that feeds the Sutherland. Removal of this ground, as well as moving the ground point to the Sutherland chassis increased only the phono buzz (as one would expect).

So the buzz is present on two inputs, from two disparate components – one analog, one digital.

Any thoughts or suggestions?

2

If I was to take a stab at it, I would say it is a ground loop based on what you have described. There area variety of troubleshooting steps to isolate/identify if this is in fact the cause, as well as potential solutions which may or may not be practical in your situation. Worth exploring…

3

Do you have a PP3 or PP5 or both? If both, do they share a ground?

4

Both. And they are plugged into a single duplex outlet – a Power Port (20A dedicated).

5

Try plugging everything into the PP5, use a power strip if needed. Still hum?

6

Everything on the PP5 was a prior arrangement (the PP3 is relatively new). The PP5 was foundation; I had two balanced iso transformers plugged in to the PP5 that fed everything.

The buzz has always been present; I’ve been on a noise reduction quest for over a year. This buzz is the last remaining noise issue – other things I’ve done have reduced but not eliminated it.

Just an additional detail: the power amps (monoblocks) are not on either PP.

7

Good idea Brett. The fact that it adjusts with the preamp makes me think it’s not a ground loop. What amps are you using? Also, do you have any networking gear around the system? It or something else could be causing some interference somewhere.

8

One of the things that reduced noise was the removal of a switch from the music room. Since I no longer network the PP5, and I went WiFi on the digital radio, I was able to just run a long ethernet cable through a wall from a switch in my office.

There’s only one device hard wired to the network, which is my Bryston BDP. The Bryston connects to the network through a Gigafoil filter, and is powered from the PP5.

I’m using Parasound JC-1 monoblocks that are powered through balanced iso transformers – one for each amp. Connections from the preamp to the amps are balanced.

9

Did you ever track this down?

10

System has changed a bit since this post — buzz is gone. Not sure which of the changes I made fixed it.

11

Got it. What’s your power topography look like now?

12

Wall outlets below are all PS Power Ports. Wall outlet power is dedicated 20A. All power cords are homemade 12ga shielded with Wattgate terminations.

Each Monoblock: wall outlet -> 1800w balanced isolation transformer
Main preamp: wall outlet -> P12 -> 500w balanced isolation transformer
Phono preamp: wall outlet -> P12
DAC, player, internet radio, everything else digital: wall outlet -> P3

Basic strategy is to separate digital from analog, and totally isolate my tube preamp from everything. My system is now completely isolated from my network — no wired connections. All WiFi.

2 Likes
13

Thanks for sharing!

Do your ITs physically buzz/hum under load or at idle? Curious – what brand are they?

Do you find a remarkable sound difference between having the Monoblocks on the IT vs the P12?

I’m looking at a similar setup.

14

The BITs used with the monoblocks are old Exact Power units (no longer available). I modified them to remove any/all other filtering components as well as the fuses. They buzz a little bit — not audible at my listening position.

The P12, as well as the P10 before it are apparently not compatible with my monoblocks. I did experiment using the P12 to power one of the monoblocks. For the few minutes it played before the P12 shutdown, I heard something similar to what the BIT achieves.