ada mp 1. How noisy is it supposed to be?

[docgorpon]

I've been building this old 80's style rack. Last night I plugged everything in for the first time. I got the ada locally, and it looks very well used. Anyway, I'm getting kind of a buzzy/hum from it. I've narrowed it down through process of elimination that it is defnitely the one creating the noise. The noise is there on any patch... clean or distorted. It doesn't seem to change tonal characterstics when things are changed or adjusted on the preamp. I have it going through a noise gate. But at full tilt, it is barely making a dent on the noise.
I knew these things were notoriously noisy. But I thought that was in relation to the gain settings. Are they usually noisy as hell from the get go like this? Or is some repair needed? PS The guy that sold it to me said it has new tubes in it. But I have no idea if it's true or not.

 

[twangbanger]

First easiest test would be to swap out the preamp tubes . I had one in the '80s and can't remember but think it had two ? if it's a 60 cycle hum you might have a ground loop , does it do it all by itself into the poweramp ? I remember it to be a little noisy especially on the gain channel and w/ the compression on w/ the clean. If you pull it from the rack and isolate it from the rail does it quit ?

 

[docgorpon]

It does it straight into the power amp. I did pull it out from the rack a bit to see if that changed the character of the hum. It didn't. It's weird. Doesn't quite sound like a ground loop to me. But it is a consistent hum that sounds like some sort of grounding issue to me. Not crackles or pops.

 

[twangbanger]

On to the tubes ! If I remember there is a setting using strictly solid state preamp w/ compression , try that to see if you lose the hum . Good luck .

 

[sizzlemeister]

Do a search for the "noise mod" and do that to the MP1. There are a few versions, one addresses mainly the capacitors, another is more comprehensive. I did the latter to both my MP1s and I do not find noise to be an issue.

Which is not to say they don't have some sort of background presence or "noise", but I think it's no greater now than having pedals in line between the guitar and amp.

You don't have to live with a noisy MP1!

I generally recap the power supply in nearly all used electronic gear. Any later electronic instrument or effect benefits from as thorough a cap job as possible, and a cleaning of the PCB, pots, jacks, and chassis. Your MP1 sounds like a candidate for this treatment and it'll thank you for it.