Help needed - unwanted pre-amp sound.

[Andrei]

I have just changed pre-amps from my Emm Labs to an Ayon Eris. I just felt like a change and in the fullness of time I will go back to my Emm Labs.
The Ayon Eris is a valve based pre-amp. It has one Balanced input (XLR connector) and the others are all single ended (RCA). It has a couple of outputs (RCA) one of which I have connected to my subs.

It is not quite in the same league as my Emm Labs and Daniel Hertz preamps but the sound is warm, and I put this down to the 6H30 valves.

The unit has been in storage for about three years.

Here is the problem: I am getting an extraneous kind of hissing. This only manifests itself when using the volume control - either via the remote, or with the volume control on the unit itself. Actually even just touching the volume control on the unit induces the sound. There is a ground switch on the rear but that has no impact on the problem.

The sound is not quite a hiss but rather a scratchy sound, similar to sandpaper. When I put my ear to the speakers I cannot detect anything from the tweeters, mainly from the midrange driver, and just noticeable from the woofers.

All connections (Sub, Amp, dac, and source components) come from the same power board.

Any suggestions?

 

[myles]

Sounds to me like the volume pot needs a clean. Carefully spray deoxit on the rear of the pot and give it a good turning up and down.

 

[Lurch]

And whilst your at it, pull the valves and clean the pins then insert and remove a few times to clean the valve sockets.

 

[Jazid]

Whilst in there have a look at the soldering of wires/pcb to the pot. If it crackles when touched (not rotated) it just might be a dry joint. Vigorous pot and valve base cleaning will more probably be a solution though.

 

[audio_PHIL_e]

And whilst your at it, pull the valves and clean the pins then insert and remove a few times to clean the valve sockets.

A mate with an old jukebox did this, and a thorough clean-up worked wonders!

 

[Andrei]

Thanks guys, I will open up the beast and check the solder joints and do the deoxit thing on the pot.

(Pot and joint in the same sentence - I'm innocent m'lud)

 

[Andrei]

Here is the scoundrel. Very small solder joint - less than half the size of a match head. Gave it some blasts with deoxit and the beast is reawakened. Also Deoxit on a few other places. I suspect this is a temporary fix, and I will have to find someone with a sharp eye and a fine soldering iron, to resolder the joint.

As suggested by Lurch I took the opportunity to clean the valve pins. I also found some sorbothane footers from an unused TT and it is singing beautifully.

Thanks for the help ! !! !!! !! !