[Trismos]

Hello all

It's been a while since I posted here and I see it's been fairly quiet. I have the M-901 and for some time I've had that rustling leaf sound through the speakers when you use the volume pot with the remote. I'm not sure about without the remote now that I think about it. I purchased one the GR Research Dual 12" servo sub kits with the Rythmik A-370 recently and I notice that when I adjust the volume these subs really jump around - a lot more than when they're playing music at even extreme levels. It's somewhat worrisome. Is there anything I can do to fix this?

Thx much

Regards
Dave

[virtue]

We could never figure out a work-around aside from removing Gary's buffer.  Quickly rotating the POT shaft (remove the knob first and power off) helps a bit, but is not a permanent fix.

I had it in my personal unit (now gone as a replacement to someone) and found it very annoying indeed.

[Trismos]

We could never figure out a work-around aside from removing Gary's buffer.  Quickly rotating the POT shaft (remove the knob first and power off) helps a bit, but is not a permanent fix.

I had it in my personal unit (now gone as a replacement to someone) and found it very annoying indeed.

I don't recall if I had the problem prior to having Jason install my buffer..... and I rather like it being in there. I take it replacing the volume pot is not the solution? I guess I could just leave the volume at max and use the digital volume control of my J. River. But I have one of those awesome aluminium block remotes that I very much like too.

Regards
Dave

[virtue]

You're a good sport, Dave.

[jb26]

Hi,

I used to get the rustling when I had the stock JJ tube in, but when I switched in a psvane 12au7 premium tube the rustling went away. Others have reported this too, and that it can be worse with nos tube stock. 

It seems that it's something tube related. In terms of sound I find the JJ and psvane similar, so it's been a relief to get rid of the rustling at $50 a tube (they sell in sets of 2 only).

I can't give you any scientific reason why this happens, only my experience and that of others.  I actually bought the psvane because of no-rustle reports and found it to be true for me too.

Cheers,

James

[brother love]

I used to get the rustling when I had the stock JJ tube in, but when I switched in a psvane 12au7 premium tube the rustling went away. Others have reported this too, and that it can be worse with nos tube stock.

I was one of those who confirmed the Psvane 12AU7-T eliminated the "rustling leaves" sound in my Sensation M451 w/ Dodd tube buffer.  After logging-in maybe 500- 600 hrs.  w/ this tube, the "rustling leaves" sound has returned on occasion; BUT if I rotate the knob back & forth 20 or 30 times w/ amp on standby, it pretty much goes away for many weeks.

[rollo]

  Had a similar issue with my Preamp [ loesch & weisner ] It was the tube. First thought, volume pot [ cleaned it] nope, then tube socket cleaned as well , nope. changed tube and all was well.
   



charles

[Trismos]

I haven't tried this yet but there's a switch that by-passes the buffer. I assume that with the buffer out of the loop the problem goes away?

[brother love]

I haven't tried this yet but there's a switch that by-passes the buffer. I assume that with the buffer out of the loop the problem goes away?

Yup.  I LOVE the tube buffer though. You can also use the mute buttom on the Virtue remote in conjunction w/ volume adjustments as needed.

[earwaxxer]

Sounds like a worn out carbon pot. You could replace it with a newer technology plastic pot, Audio Note has some good ones under the TKD brand.

[srb]

Sounds like a worn out carbon pot. You could replace it with a newer technology plastic pot, Audio Note has some good ones under the TKD brand.

If it was the pot, then I would think it would also make the rustling noise with the tube buffer circuit bypassed.
 
Steve

[Trismos]

I have an EAT Cool Valve 803S that cost me $200.00 by the time I got it here. It would riffle my cookies good to find out the circuit wasn't compatible with this tube (ie if the Psvane 12 AU7 works better - they're supposed to be swappable). And it seems to be a curiosity that fooling around with the volume control - rotating the knob a bunch of times - makes any difference.

[virtue]

Oxidation in the POT seems "activated" by the high-impedance follower. 

I never heard of a plastic POT that does not oxidize but it would seem to me that would work.  Love to hear more about this.

[ericlp151]

Interesting.  This thread started making me read about Pots... And all the different ones...

http://www.diyaudio.com/forums/chip-amps/40676-so-i-did-try-all-those-different-potentiometers.html

This might make for some interesting reading if your up to it.  I find it amazing how people can hear the difference in a "Musical" pot over another.  But my take is even if you find that pot that is perfect for you ... Over the use of turning it up or down is going to change the sound with time.

Funny thing is I have a Trends TA10.2 amp and you can change the jumpers to bypass the Pot to make it a power amp. 

[HiFlight]

The rustling sound is caused by a very small amount of DC voltage on the pot.  This likely comes from a tiny bit of offset voltage from the buffer tube.   It is a common occurrence with many tube amplifiers and preamplifiers and can often be eliminated or greatly reduced by choosing a different tube.    A  "dirty" pot can also cause the same symptom, and can usually be cured by rapid rotation of the volume control (with the amp turned off, of course) but in a clean environment, this is rather rare on new equipment.  Very common on vintage equipment.