I have monoblocs each w/their own grounded cord and a preamp w/o a grounded cord. The problem is that I'm getting a slight ground hum from each amp. The amp manual says if this happens to use a cheater plug on the amps and to ground "at least one other component." Is it possible to ground my preamp, and if so how? Many thanks for any advice.
You can run a wire from your preamp. either the ground post or one of the screws holding the case, to the center screw in your AC receptacle. Sometimes this helps, sometimes not.
I used to have this problem with big Parasound amps, and the cheater plugs actually did cure the problem. Didn't have to ground any other components, either
The preamp, being the heart of the system, should be grounded. The amps, for safety reasons, should be too, but for audio reasons (ground loop prevention) they should not. If the amps hum when grounded through the AC cords, it indicates that the manufacturer has not done their grounding homework (it is possible to have the amps grounded and **not** hum at the same time)- so the best method probably is to float the grounds of the AC cords with cheaters.
At any rate the preamp *should* be grounded, although I suspect it already is since you are getting the hum.
Wow, this is more complicated than I thought. I think I will try your suggestion first, Stingreen, to see. BTW, the amps are the only grounded components (CD, DVD, and preamp are all non-grounded). Am on work travel, but I'll report back when I get a chance.
Tvad, I do have have Ground Zero and used it in various system configurations. It definitely works, but requires quite a bit of fiddling, and in some cases is not 100% effective. I have to admit though, I probably didn't have enough patience to follow the protocol to the last letter.
I have a Granite Audio grounding system. You can hear some reduction of noise with some settings, but it does not resolve a ground loop problem.
I have yet to find a system that was not improved making the preamp the only grounded unit. Some are very concerned about the possibility that and amp can have the hot wire somehow come in contact with the chassis and a person who is grounded come in contact with that chassis. There is certainly some probability of that happening but it is very remote. Canada doe not allow cheater plugs to be sold, which is over the top in my opinion. Synergistic Research sells the best cheaters that I have ever heard.
Rather than use cheaters I disconnect the ground wire at the IEC end of my PC. Of course, you can only do this if the PC has a removable plug, like Oyaide, Watt Gate, etc. Only my preamp is grounded and I do hear a reduction in noise, but depending on the amp I'm using, it may not solve all the problems.
I've been told that if one uses interconnects that are shielded, it's best that the shield is connected to the ground at one end of the cable. I've also been told you can disconnect the entire ground at one end of an interconnect. Never tried it, but maybe someone here can comment on that.
Rrog, disconnect the interconnects from your amp and turn it on. If there is still hum, you have a problem in the amp. This is unlikely. If not put the ic between the preamp into the amp, but with nothing plugged into the preamp. If you have hum, it is the preamp. If it is in one channel, that is the problem. This is improbable. Switch the ics at the preamp. If it switches, it is the preamp.
If no hum, connect one source. The one that adds hum is the problem. Put a cheater on its pc. If that doesn't help it, it is in that source.
Clio09: I've been told that if one uses interconnects that are shielded, it's best that the shield is connected to the ground at one end of the cable. I've also been told you can disconnect the entire ground at one end of an interconnect. Never tried it, but maybe someone here can comment on that.
Tvad: Correct. The end that connects to the preamp should have the shield connected. The end of the IC that installs at the amp(s) or sources has the shield unconnected. This also goes to the issue of directional indicators on some interconnects, which will point to the end that has the shield connected (rather than indicating signal flow).
That is correct, but only in the case of interconnects that do not use the shield as the signal return conductor. Or interconnects that have an inner shield used as the return conductor, and a separate outer shield, which may be grounded at only one end. It is common, especially among lower priced interconnects, for there to be one shield, and for it to be used as the signal return conductor, in which case disconnecting it at either end would result in very loud hum.
Also, based on what I've read different manufacturers do not always define the arrow consistently, in some cases having it point to the end at which the shield is grounded, and in other cases having it point in the direction of the destination component.
You must have a verified phone number and physical address in order to post in the Audiogon Forums. Please return to Audiogon.com and complete this step. If you have any questions please contact Support.
