Aleph 1.2 hi frequency noise

[Steve Fay]

Hi guys
I really need some help! I've had my Aleph 1.2 mono blocks up and running for about 100-120hours or so. They sound great with one exception a groung loop hum in one side,but not the other. At times I'm able to get rid of it for short periods of time or at least get it down to a reduced level where I can tollerate it. Ive read every thread her on the subject and the internet. I just don't get it. Ive changed interconnects and many internal changes also. So today I decided to disconnect the star ground from the chassie ..... hum ......gone. These amps are dead quite with the rca interconnect disconnected. So with the star ground lifted musical heaven, then out of no where I get a real high pitch squeal out of my spearkers I ran over and turned off the amp.I'm attaching a rough drawing of my internal wiring. I sure hope some one can helpppp.

Thanks
Steve

[Steve Fay]

I'll try the attachment again. I dont know what I did wrong with starting two identical threads??

[pinkmouse]

Ok, if it happens in one, and not the other, then there must be some difference between them. The first thing to do is reconnect your star to the chassis.

1, Are they running from different power sockets?

2, Is the cabling the same?

3, Have you tried swapping the two monoblocks around to see if that makes a difference?

4, Do they use the same type of transformers?

5, Have you had them open next to each other and compared the routing and layout of each internal wire?

Those things should get you started. As for your duplicate thread, it has gone, ( ). However, I can't see the images you posted, they seem to be broken. They are also quite big, it would be polite to scale them down a little for people with slower connections. 600pixels wide is usually fine.

[Steve Fay]

Thank you pinkmouse
1 yes they're running from different outlets but on the same circuit. Is that ok?

2 all the cabling is the same

3 yes I have tried switching them around.

4 both of the transformers are the same

5 I did build them side by side but a good question.

I'll see if one of my kids can show me how to scale it down

Thanks
Steve

[pinkmouse]

OK, so when you switched them, did the noise stay with that amp, or stay with the power outlet? Depending on the loads on the wall circuit, different outlets can have different earth potentials.

Have you tried lifting the screen from the signal cable? DO NOT lift the mains earth.

If your wiring checks out, then there must be a faulty component or dodgy solder joint.

[Steve Fay]

Hi Pink Mouse
I don't understand what you meant by lifting the screen. what is the screen.Please excuss my inexperience. Also by reattaching the star ground will that get rid of the squeal?

Thank you
Steve

[Steve Fay]

I'll try to attach the drawing again and I think I've reduced the size. Fingers crossed. Here goes...........

Thanks
Steve

[Steve Fay]

Sorry for wasting every ones time but I really need some help.I zipped the drawing hopefully it works.please

[pinkmouse]

Originally posted by Steve Fay
I don't understand what you meant by lifting the screen

Take one end of the signal cable and cut or unsolder the sheilding wire(s) that run around the core from the connector. This is called lifting the signal earth/screen.

Also by reattaching the star ground will that get rid of the squeal?

You should do this before you do anything. By removing the star ground you have made the amp unstable, that is what caused the squeal. This is a highly dangerous situation and can lead to overheating and/or permanent damage to the output stage.

btw, I still can't see your pictures- email one to me and I'll post it for you.

[Steve Fay]

Pinkmouse
Thank you so much for your repleies. this week is so busy and that info sure helps. I think that one of my problems is the connection at the neutrik XLR. I was taking pin one back to the star ground. my understanding is it should go to the chassis. On the XLR chassis connector there a extra lug possilby also a ground connection?

Thanks
Steve