QuestionHello. I'm in desperate need of help.
I have an NAD 2200 (amp), NAD 1130 (pre-amp), Rotel RCD-955AX single-
disc CD player, and Pro-Ject Audio Debut III turntable (w/ Ortofon OM-5E
cartridge, factory mounted and aligned).
The turntable has a standard RCA plug for connection to the pre-amp. The
CD player is connected to the pre-amp using a Monster Cable M550i audio
interconnect. The pre-amp is connected to the amp using another Monster
Cable M550i interconnect.
Here's the problem; sometimes, there is intermittent "static" coming from one
channel. It's most noticeable when listening to softer music (it may happen
when listening to loud rock, but I'd never hear it).
It happens whether I'm listening to the CD player or turntable, so I've ruled
out a source problem. And it's not the usual pop and click from vinyl static,
it sounds more like the music is "staticy". for example, sometimes during a
piano sonata, each piano note has "static" surrounding it. It happens most
days, somtimes every few minutes or so, and sometimes I can get almost
through an entire CD or LP before it happens.
It can occur in either the left or right channel, but appears to happen more in
the left. I tried switching interconnects, but to no avail.
I took the covers off of both pre-amp and amp, and noticed no cold solder
joints, bridging, etc. Everything looks good. I used contact cleaner and
cleaned all pots, switches, etc., again to no avail.
I suspect either the amp or pre-amp, partly because they are 15-20 years
old. However, I love the sound of these pieces, and am not sure what to do.
I'm in the Nashville area, and they're aren't any local repair shops (only pro
audio).
There are a few vintage audio stores on the 'net, but I'm not ready to ship
these things off for repair (since I'm not sure what the issue is).
Any suggestions? Thanks in advance!
AnswerI think you have a noisy component in one of the circuits. It can be a coupling capacitor, transistor or IC.
Here is what you can do:
ONE: Disconnect all inputs to the preamp.
TWO: Listen with no signal but with the volume gradually increasing until you hear the noise. Identify which channel it is coming from.
THREE: Now, turn off the preamp. Does the noise go away or stay? If it stays it is coming from the power amp.
FOUR: If the noise goes away with preamp off, power it back on but turn the audio level down as low as it can go. If the sound goes away it means the noisy component is in front of the volume control. If it stays with volume control down it means the noisy component is after the volume control of the preamp.
The above testing can help you when you take it to the tech; it will save much of the diagnosing that would otherwise need to be done.
I suspect the noisy component will only cost a few dollars to replace and the labor charges a few dollars more. If you are handy and know how to solder you can just go in and replace all the coupling caps and see if that doesn't solve the problem.
Let me know if you need more. You have some good equipment that is well worth debugging. Good luck,
c
