Scratchy volume...

hochpt21

Just unpacked and hooked up a new-to-me Musical Fidelity a308. She is a beauty!

I hooked up my turntable, and played a record. I was slowly upping the volume knob and at about 11 o'clock I heard a startling scratchy sound. I turned it down and nothing. I then lifted the tonearm and tested the volume with no sound. At the same spot (about 11 o'clock) a scratchy sound. When I let go nothing.

I've since played a few records and whether anything is playing or not...there is a scratchy sound while the volume knob is moving between 10 and 11, but as soon as I let go it is fine.

Any ideas out there?

mhardy6647

Well - I know nothing about this product... but... if the volume control is actually a potentiometer (as opposed to a binary-encoded switch operating in the digital domain) it (the pot, that is) may well be "dirty" (oxidized) and due for a cleaning.

There are other, somewhat more dire possibilities (as the impedance of the volume control is probably near its maximum where you're getting the noise) - but assuming the product has a little age on it and employing the principle of Occam's Razor*, a dirty pot is the first thing to check for, IMO.

*Occam's Razor, in a nutshell: The simplest explanation (i.e., that requiring the fewest assumptions) for a given phenomenon is usually the correct one.
http://en.wikipedia.org/wiki/Occam%27s_razor

EDIT: Here is a guide to cleaning pots, switches, and controls:
http://www.audiokarma.org/forums/showthread.php?t=207005&highlight=idiot%27s+guide+deoxit

hochpt21

I turned the power off and ran the volume knob up and down about ten times and it seemed to have lessened the severity significantly. Although not completely.

Maybe the previous owner never turned the knob that far and it just needs some time to go away?

mhardy6647

That is a quick and dirty way to clean a pot -- it's better to fix it right (from my perspective), but if you get it to the point you're satisfied, that's fine.

tonyb

De-oxit baby.

Hows she sound otherwise ?

hochpt21

I will need more time of course, but here are my initial impressions after a variety of rock, jazz, blues and vocal albums.

Extremely quiet/silky black background. I've got her plugged directly into a dedicated 20A outlet with a SignalCable PC and it is spooky quiet.

Musicality is quite stunning. The Antem 225i I tried with this system was good. Very good, but just lacked ever so slightly involving me in the music. It presented the music nicely in so many ways, but just left me wanting a bit more. Like, wondering if it was really good or if I just wanted it to be really good.

The MF doesn't leave me wondering. It has surprisingly smooth, deep, accurate bass, and midrange is something special. Highs are crystal clear without ever being sharp.

It just sounds rich (which is a term I've never used before in audio, but maybe because I haven't experienced it). Richy rich rich....but with superb detail.

You know when you watch a movie and after the previews there is the little audio blurb...you know the lion roars or whatever and it sucks you in and focuses your attention? That is what this sucker does...it just draws you right in.

Obviously, I'm excited, and looking forward to spending more time with this thing.

Mikey081057

Agree with TonyB.... Use Deoxit GOLD though....they call it gold cuz it costs almost as much but superior to anything out there...

hochpt21

So far, just from listening to albums today and turning the volume up and down while switching records, the scratchiness is eliminated.

I e-mailed the previous owner and he said it had not been used much in the last couple years so possibly that was part of the issue.

chumlie

Happy to hear your sticky pot problem is solved and your enjoying your new rig Paul. Congrats !!!

Jim Shearer

For noisy potentiometers, both rotary and sliders, I use Deoxit Fader Lube. The contact cleaner is great for switches & connectors, but contact cleaner will remove the lube from a pot, which will lead to wear & failure in the long run. If the pot is not cleaned sufficiently with the fader lube alone, then I might try the contact cleaner followed by a squirt of fade lube.

Cheers, Jim

tonyb

Glad your digging the MF pal....their sound certainly "draws you in" as you described. No listener fatigue with this puppy huh ?