[rjoseph]

I recently bid a B&K AVP-2000 preamp from ebay and won it cheap. Since I have active monitors, I was looking for a preamp preferably with XLR outputs. The AVP-2000 had them which made it the best I could find for the mackies.

The preamp is good and is fully functional. However, I hear a pretty audible buzzing noise when sources are connected to it. I have the TT and CDP connected to it and I hear the buzz on both. I have alternated between XLR and RCA outputs and still hear it.

I have using a different power outlet than the speakers for the preamp, which I am. Please suggest how I can get rid of this noise. Other than that the preamp is pretty solid.

The input/output options are the same a the AVP-1000 listed here. AudiogoN ForSale: B&K AVP-1000

EDIT: the 2000 is actually got a lot more options at the back but for my purposes I just use the XLR pre-out as shown in the 1000.

 

[NightOwl]

Try the rca tape outs from the B&K to the Mackies. That will be a line level signal. The preamp out might have too much gain for the Mackies.

 

[rjoseph]

Thaks Nighowl but it didnt work. I tried that and still got the same result. I lost the volume control from the preamp in this mode and had to use the volume knob on the mackies.

Any other suggestions?

 

[NightOwl]

Do you get the buzzing when you have just the cd player connected and not the turntable? Do you get buzzing when you have no sources connected to the B&K?

 

[rjoseph]

It seems to be the preamp. I get the buzzing immaterial of the source. Could it be a grounding issue?

 

[NightOwl]

95% of the time that's the problem. You could try a longshot. You can occasionally get noise from your house circuit wiring. You could try an extension cord and a wall outlet on a different circuit.

 

[rjoseph]

When I connect the TT and pro-ject phono directly to the mackies I do not get the buzz. It leads me to believe the grounding could be the issue within the preamp. Is there anything I can do within the box to eliminate the buzz?

 

[NightOwl]

Quote:

Originally Posted by rjoseph /img/forum/go_quote.gif When I connect the TT and pro-ject phono directly to the mackies I do not get the buzz. It leads me to believe the grounding could be the issue within the preamp. Is there anything I can do within the box to eliminate the buzz?

If you have a 3 prong plug from your B&K, you could try a 2 prong cheater plug on the end of your 3 prong plug to see if that corrects it.

Other than that, you'd need a schematic or pictures of the preamp's internals for the grounding topology.

 

[WesMiaw]

A cheater plug should only be used as a temporary solution or to diagnose the problem, as leaving it in could be dangerous.

You can also try running some copper wire between the chassis of your source and pre-amp to see if that reduces or eliminates the noise--that should ground them to each other. The connection needs to be at an unpainted part, so connecting at screws might work best.

You can also try lifting ground on one or more of your XLR connections. You can buy an XLR ground lift adapter for a few bucks off any pro audio web site. This has worked for me in the past--one of the connections has to remain connected so at least one ground connection exists.

Have you also tried plugging everything into one power outlet by using a power strip?