scratchy volume controls, how to avoid?
Jun 4, 2008 at 11:17 PM Thread Starter Post #1 of 18
warpdriver

warpdriver

Headphoneus Supremus
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I notice that some volume controls get scratchy after a while and need cleaning/servicing.

Is this preventable? I am running my Micro Amp on most of the time. Should I turn down the volume after I finish using it, or keep it in the same position most of the time?

BTW I just received my Micro Amp. It's a knockout, I liked my old one but this new one is even better.
 
Jun 4, 2008 at 11:53 PM Post #3 of 18
Quote:

Originally Posted by Uncle Erik /img/forum/go_quote.gif
Try some of the ProGold contact cleaner, or similar product. Those clean out pots and protect against corrosion. Usually works great.


Ditto. I use contact cleaner every 2-3 months, and clean all my input/output jacks and connectors, interconnects and power cable prongs. And yes, it gets rid of that annoying crackling in the volume pot
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Jun 5, 2008 at 12:21 AM Post #4 of 18
just wondering, how do you apply this?
 
Jun 5, 2008 at 12:56 AM Post #5 of 18
it's just an aerosol spray (like you would spray WD-40)

Does not moving the volume knob help prevent this problem?
 
Jun 11, 2008 at 12:55 AM Post #6 of 18
Quote:

Originally Posted by warpdriver /img/forum/go_quote.gif
it's just an aerosol spray (like you would spray WD-40)

Does not moving the volume knob help prevent this problem?


To answer your question, warpdriver: moving or not moving the volume control is not a factor. The reason for the crackle, usually has to do with the fact; that air-borne micro-fibres, dirt and dust are in all our homes (not to mention our bodies and clothes), no matter how clean you think you keep your stuff or yourself. They float through our air, and eventually settle on something. If, in their travels, they became static-charged (and decided to settle on your volume pot; which, if you have a good-one, will be very sensitive to such intrusions); you will experience this crackle. Easiest solution for me has been: compressed-air (to blast-out the dust), and contact-cleaner (to clean and wash-away) what the compressed-air didn't get. Has worked great for me everytime.
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Jun 11, 2008 at 5:09 AM Post #7 of 18
So you experience noise even when not moving the volume control?

I have an old Total Bithead that is being noisy for some reason; I was just about to send it back to Headroom to have them look at it until I looked at my checking account and Headroom's rate for out-of-warranty work ($50/hr). Maybe I should try blowing it out first.

Headroom volume controls often scratch when you adjust them, but mine has always been quiet when I was not fiddling with it.
 
Jun 11, 2008 at 2:10 PM Post #9 of 18
ok, thanks for the responses, I guess I should just use the Progold when it starts to happen
 
Jun 11, 2008 at 3:10 PM Post #10 of 18
Quote:

Originally Posted by trains are bad /img/forum/go_quote.gif
So you experience noise even when not moving the volume control?

I have an old Total Bithead that is being noisy for some reason; I was just about to send it back to Headroom to have them look at it until I looked at my checking account and Headroom's rate for out-of-warranty work ($50/hr). Maybe I should try blowing it out first.

Headroom volume controls often scratch when you adjust them, but mine has always been quiet when I was not fiddling with it.


The old Bithead line had an inherently crackly volume pot not for reasons of dust etc. This could have been eliminated with extra circuitry in the signal path which would have degraded SQ. They chose the better SQ solution. The newer models and all other product lines do not have this 'issue'. It is somewhat misleading to say that HR amps have a tendency towards scratchy volume controls when they are no different in make or implimentation than other manufacturers...
 
Jun 11, 2008 at 3:15 PM Post #11 of 18
Edit -- Doh! The Sloth beat me to the button! Thanks Daniel!

Quote:

Originally Posted by trains are bad /img/forum/go_quote.gif
So you experience noise even when not moving the volume control?

I have an old Total Bithead that is being noisy for some reason; I was just about to send it back to Headroom to have them look at it until I looked at my checking account and Headroom's rate for out-of-warranty work ($50/hr). Maybe I should try blowing it out first.

Headroom volume controls often scratch when you adjust them, but mine has always been quiet when I was not fiddling with it.



The scratchy pot in the old AirHead is virtually by design and there's nothing you can do about it. We got so much grief about it we changed the design in the latest version. Basically, in a single power supply design the audio signal is not a zero volts average. We used a design that had the fewest possible caps in the signal chain, but had the undesirable problem that the DC offset of the audio signal went through the pot. When you adjust the pot it amplified the surface noise of the pot because of the offset. In the latest edition we put a DC blocking cap in before the pot and the symptom went away. We made other real improvements too, but putting the DC blocking cap in there did give the sound quality a hit, but on the whole the new units sound better than the old.


So don't send your AirHead in, there's nothing wrong with it, the noise isn't there when you are not turning the pot.

On the new units I believe we use seald pots, I don;t think spraying stuff from the outside will clean the pots. I'm also surprised you hear noise when turning the pot because since they are sealed it shouldn't really happen. If you have significant noise when turning the pot you should get ahold of mikeo@headphone.com and inform us of the problem.
 
Jun 12, 2008 at 4:22 AM Post #13 of 18
Quote:

So don't send your AirHead in, there's nothing wrong with it, the noise isn't there when you are not turning the pot.


The noise IS there when I'm not turning the pot. As an EE graduate student, I understand the scratchy volume control and have no problem with the decision to leave the volume controls scratchy.

But my Bithead is actually broken, and makes noise for lack of anything better to do at the time. Sometimes looking at it sternly or giving it a good smack makes it shut up, but it really sounds like a bad connection inside or something; it kind of sounds like someone blowing on a microphone.
 
Jun 12, 2008 at 4:43 AM Post #14 of 18
Quote:

Originally Posted by warpdriver /img/forum/go_quote.gif
ok, thanks for the responses, I guess I should just use the Progold when it starts to happen


Well worth keeping it around. It has come in handy a lot for me.
 
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