P2075c

[jdsalinger]

Hi folks,
I have a P2075c that I bought locally a couple weeks ago for home hifi use. So far, it sounds pretty good. Kinda seems like it was intended to be a pro monitor type of amp. Pretty forward and detailed. Wide sound stage and very revealing. Kind of "studio" sounding, but also very dependent on the recording quality. I'm still getting used to it, but I think for the price these amps are getting on ebay, this would be pretty satisfying for someone starting out.

There is a minor issue of some momentary drop in volume in one channel or the other. I'm not sure, but I think that sometimes it manifests itself as slight distortion. It typically happens when the amp is cold or even when warm, but no sound coming through (like when I leave it on for the afternoon and then come back to listen).

I have inspected the solder side of the board and the joints look perfect. All shiny and not a single evidence of a crack. The component side of the PCB looks like new. Nothing burnt, leaking, broken, melted or even dusty.

I de-oxited the Alps volume pots (totally enclosed, so probably pretty good anyway).

Fortunately, the number of caps is very small and not even really that many transistors, so if I have to recap it, it won't be terribly hard. But I wonder, is there anyone with knowledge of the P2075 or P2075c that could let me know if there are any known common issues with this amp? Does this type of intermittent cutting out sound like a resistor, a cap or a semiconductor?

How reliable are the Darlington power packs?

I'll try to explain the behavior better when it happens again.

 

[bberkom]

Is there a speaker protection relay? Looks like there is, but can't tell for sure. Does the sound come back when you start playing music and bump up the volume a little? Could just be dirty relay contacts.

 

[jdsalinger]

Yes, it has a relay. Honestly, it is so infrequent and intermittent that I could live with it. But if it IS something like dirty relay contacts, then the OCD side of me would want to try to replace the relay.

Kinda just wanted to start a P2075 thread to see if anyone had any words of wisdom and because I couldn't find much info on the web for these. If others want to comment on the P2075, please feel free to post here.

This amp doesn't look like much but it is satisfying. Probably not the last word in detail, air or holographics, but like I said, it's very revealing and well worth the market price. Listening to "eu vim da bahia" by Joao Gilberto and it had that realistic sound, like he's singing in your ear (not to be gross....it's just how they record him) and the guitar and high hat are crystal clear.

 

[zaibatsu]

Depending on which relay it is, you can carefully pop the cover off some of them, and inspect the contacts.

You can also clean them with some printer paper and deoxit (just wet the paper and slide it up and down or side to side sandwiched between the contacts while you hold the relay closed with your finger + repeat until black stuff stops coming off).

It's best to replace the relay with a new one if that's the problem, but it's handy to test before spending money.