Speaker buzz with SS amplifier, input disconnected

Audiobrian,

Buy a pair of shorting plugs for the inputs of the Gamut monoblocks. If you still have the buzzing sound heard though the speakers try plugging the amps directly to the wall outlet and then check again for buzz.

If the buzz still exists.
Which Gamut monoblocks do you have? Are the amps enclosed in the same chassis unit or entirely separate units? If the amps are housed in the same chassis unit the problem could be the monoblocks unit.

It is possible some electrical appliance or device in your home could be causing the problem. It could even be a problem somewhere in the electrical wiring like a loose connection that is slightly arcing. Only way to rule out the mains power is to hire someone with a background in Power Quality and connect a scope to the mains of your home.

This sounds like an internal layout problem to me. It is true however that with an open input (nothing connected) that there will be a greater amount of noise present. But that should be gone with your preamp connected.

Now one exception may be that your interconnect cable is responsible for some of the buzz. So it is a good idea to try a different cable before blaming the amp!

Thanks Attmasphere/RK
I've tried a couple of interconnects without change. I believe you are right about an internal layout problem. Both monoblocks buzz through the loudspeakers, one louder than the other, inputs either connected or not.
Would you kindly expound on the type of layout problem which might result in this speaker buzz. Can a noisy toroid transmit buzz to loudspeakers etc
I know most talk of noisy transformers in the chassis without transmission to loudspeakers.
Many thanks for your response!

Like Arh is asking above, is this a really bad hum/noise or is this just the tiny hum you might get from a floating input?

When 60 Hz hum becomes really bad, it can create a buzzing hum. The 60 Hz wave is so strong that it clips off at the peaks and creates many new frequencies that are higher order harmonics of 60 (120, 240, 480, 960 Hz, etc.).

If this is a pretty loud hum, then it sounds like you have either had a big electrolytic cap in the power supply going bad, or there is a short in the amp that is so bad it is bleeding the power supply down. If it is an internal short, then it will smell bad and be overheating. If it is just an electrolytic filter cap, it might slightly smell acidic, but won't be overheating that bad.

Anyway, sounds like she needs an overhaul.

Hi Brian- I had a similar issue with BAT monos a while ago. I would get a hum with the speakers connected and no input connected to the amp. Your amps were designed to run with XLR input and the amp will hum if there is no device plugged into the XLR inputs, so hopefully you have a preamp that has XLR outputs. IN the manual of your amplifiers, it states "In case you have a preamplifier with only RCA outputs, you can use the RCA input. Remember to plug in the XLR Terminator plug, when you use the RCA input. It connects the negative input to ground, making sure that the input is not “floating” with the risk of noise or oscilliation comming in to the amplifier circuits." So - connect the inputs of the amps with an XLR cable to the outputs of a balanced preamp and the noise should disappear OR use the RCA inputs to connect to the preamp and use the XLR Terminator plug as described and the noise should also disappear. I hope this helps.