"Buzz" Coming Through Speakers

Replace the dimmer switch with a regular switch.

You may try lifting all your cables off the floor, making sure no cables are touching one another, and crossing cables at a 90 degree angle -- not parallel.

In the past, changing the tubes resolved the problem. But not this time.

It appears that the line stage version of the SP16 uses three 12AX7's, and the version which includes a phono stage uses three more. Not sure which version you have, but in any event it may be worthwhile to try swapping the tubes around among the various locations in the preamp.

Regards,
-- Al

The first thing to do is verify that the preamp is indeed the culprit. To this end:

run the amp with no input- no interconnect cables attached. Is the buzz still there? If yes- its the amp, if no:

Reconnect the preamp. Do not have any other component attached. This is important- if a ground loop is causing this it can be coming from another component. Is the buzz present? If no, swap the interconnect cables left for right at the preamp end and see if the problem moves. If it does, the preamp is indicated. If it does not, its a cable.

If yes, in both channels: Try floating the ground pin of the AC power cord as suggested on this thread. This is for testing only. If this fixes it, you need to talk to the manufacturer about fixing the preamp's ground problem. If it does not, you need to talk to them about fixing the preamp- any number of internal faults can cause this.

Good Luck and please report your findings.

I'm in 100% agreement with Atmasphere. You will see many suggestions to use a cheater plug permanently to eliminate (mask) a ground loop problem. As Atmasphere suggested, use it only to identify the problem with the amp or pre-amp. After you have identified the problem, fix it. not by using the cheater plug permanently, but by actually fixing the problem. It could be a wiring problem in your house or a problem with a component. Sometimes it can be the interconnect cables. lifting the ground on a permanent basis is not a good idea. It is actually akin to removing your brake pads in your car. You don't need them until you have to apply the brakes. using a cheater plug removes the path to ground. If there is a fault, electricity will try to find another path to ground. It may be you, your pet, your family member, etc. I would bet that it is a problem in your amp or pre-amp that has come about recently. A faulty power supply filter cap or something else in the amp or pre-amp. If it was working fine before, maybe a dimmer switch is going bad. Some dimmer switches click off completely and some only turn down but not completely off. I know you will find the problem and resolve it.

enjoy