Screeching noise!?

[Eric116]

Hi,

I am an absolute beginner in anything audio related, but here is my problem. i have a second-hand Audio Research SP9 pre-amplifier and a McCormack Power Drive DNA-0.5 driving a pair of B&W Nautilus 800s. The combination has worked fine for some time, but since a bit, whenever I turn the volume up, absolutely terrifying screeeeching sounds come out of the speakers (particularly the left one).

I reduced the gain control level by 6db on the pre-amp unsoldering a connection according to the manufacturer's advice. While this has helped, the problem is not solved. The screeching sounds still come out when changing sound volume, particularly at fairly high levels.

Is this unique to the material I have?
Could it be damaging the speakers?
Are there any fixes?

Thanks!!
Eric

 

[halojoy]

Is it only while you turn up/down the volume pot,
or is it remaining after you have set the volume?

If it is only when turning,
you should exchange the volume pot.

/halo - have heard some noises from vol controls

 

[Netlist]

Hi Eric
Welcome

First thing I would try is to find out if your problem comes from the pre or main amp. This could easily be done by connecting a cd-player (with volume control) directly to the main amp. If the problem is gone, it's the preamp, otherwise its the main amp.

BTW, I own a pair of B&W matrix 800's, powered by a nice DIY-amp. Ever compared the sound with your Nautilus?
What exactly do you mean by Nautilus 800? Pictures? On the http://www.bwspeakers.com site?

Hugo - would adice: watch your speakers!!

 

[Sch3mat1c]

Is it a high-frequency screeching that's unpleasant, but seems to be part of the music? I think I once heard that is IMD produced in the speaker...no idea...

Tim

 

[Eric116]

Hi all,

Thanks for your resonses! Hooking up a cd-player directly to the amplifyier and playing with the sound knob revealed a total absence of the awful screeching when increasing or lowering the sound level!

I would therefore conclude from the posts and this little experiment that the problem lies with the pre-amp rather then any of the other component.

Where should I take it from there? Is it a matter of replacing the gain on the pre-amp? Or is there an easy fix to this?

Oh, and by the way, the speakers are the Nautilus 804. Quite wonderful speakers to my ears! Not sure how to insert a picture, but one can view them at http://www.bwspeakers.com/index.cfm...&ObjectID=BE4FF6D9-5CAB-11D4-A68100D0B7473B37

Thanks a lot for your responses

Eric

 

[Netlist]

Since you could locate the problem in the pre-amp, and the pre-amp is a FET-Tube combination, we will have to ask the chaps from the Fet and (or) tubes.
This goes far above my head.

I'm sure they will read this thread and jump in

/Hugo - only knows the nice glow of the tubes...

You might post your question in the tubes section, I'm not sure the tube-guys come her often.

Did a little thinking, and I reckon it will be a tube. (Just a feeling)