I am hearing a “small” amount of hum with no inputs selected. By small I mean you cannot hear it if your ear is 2 to 3 feet away from the speakers. Is this meant to be “acceptable” or should there be zero hum.
There is a very small hum with just the DAC connected and no power to any phono component. If I add power to phono components hum slightly increases.
Components are:
BHK Signature Preamp
BHK Stereo 250 Power amp
Power Plant 12
Directstream DAC
I would start with disconnecting everything but for the amp to the speakers. Than reconnect each component listening for the culprit. Take a look at the how to <–link for addressing hum.
If he’s running XLR between the fully balanced BHK pieces and SE from the Sutherland he may try lifting the ground on the the two preamps one at a time.
I don’t think I know exactly what tube hum is, my sound is a king of buzzing. Previously I had what I thought was a pretty bad “electrical” hum. I have a pretty long run (8 feet) between my preamp and amp. When I changed the amp power cable to a high end shielded cable that hum went away.
The current buzzing does not change when I change the preamp volume.
My setup does have the amp, phono amp and turntable about 8 feet away from the rest of the equipment - no choice with my space issues. I am not using XLR cables between preamp and phono – Sutherland does not have XLR outputs.
Gain on Sutherland is 58, although buzz is still there (although a little less) even with phono amp and turntable plug pulled - so just the DAC, pre and power amp left.
1). Only amp and speakers - “small” amount of hiss – out of highest tweeter, disappears at about 18" from speaker. This is with room totally quiet, so even original hiss with ear right up to speaker is pretty low. All my measurements will be based on this standard.
2). Amp plus pre with XLR cables, but with no power to pre amp, and no inputs to pre – no hiss (weird).
3). Amp plus pre on (volume 40), no inputs to pre - hiss audible to about 30-36" away from speakers. Zero afterword. Now top and mid tweeter.
4). Amp, pre and DAC - hiss to about 44".
5). Amp, pre and Sutherland phono amp, preamp set to phono input. Hiss to 60’-72".
6). Same as above with turntable motor on. Hiss to about 72" to 84".
In all of these cases I have to listen very hard to hear hiss - but it is there at distances below the thresholds mentioned above.
I first suspect the tubes in the preamp and would try a replacement set, but the fact you get more hiss with adding components makes me think your cables or something else are picking up noise.
I changed the tubes in both the pre and the amp. Changing the tubes in the amp made no difference that I could sense. Changing the tubes in the pre did help a little. For example, previously I could stop hearing the hiss at about 5 to 6 feet, now it is down to about 4 to 5 feet.
I guess all that is left are the cables - likely the 8 foot run between pre and amp.
Also, I made an error in an earlier post. When the volume of the pre is turned up, especially to very high levels, the hiss increases.
What amount of hiss is normal for equipment like this - a little, none?
You and I have very similar systems. My speakers are about 89dB efficient. I do hear a bit of hiss from 4 feet(?) away. I’ve never thought twice about it because I can’t hear it from my listening position, and once I have music playing, even at VERY low levels (volume 5 on the pre) I can’t hear it at all.
Thanks for the comparison to your system. Sometimes you just want to find out that “I am normal”. I guess I will stop being paranoid and just enjoy the system.
