RA280 scratchy/dusty volume potentiometer

#1

Hi,

I recently bought a new RA280, after using it for a week I noticed adjusting the volume control scratchy/dusty sounds come out of my speakers (Harbeth) - typically most pronounced around10 - 12 O clock, it happens on all inputs, and is unrelated wether there is music playing or not.

typically this has been the case for me with very old amplifiers that over long time would get dust/corrosion in the volume potentiometer and would require service/cleaning - understandable for 20 year old amps, but I was surprised to hear it on a new RA280 after a week of use!

I also noticed this with another RA280 that I had for a demo before from a dealer.

Is there a manufacturing issue with the potentiometer? A resistor ladder would have been a better choice, but nevertheless this is a very costly amp, I would hope I wouldn’t have to worry about servicing a potentiometer after a week of use! It should be more like 10 years.

Anyone else has this problem? You can easily test this by selecting an unused audio input (to ensure no audio is playing) on your amp and slowly moving the volume control from 0 to max.

#2

@lime

We apologize for any inconvenience caused.

The analog volume part itself is physically coated with carbon resistance in a continuous structure.

When you adjust the volume, there is always something called sliding noise as it moves along this carbon contact surface.
This tolerance for sliding noise is set by the component manufacturer in compliance with quality standards at the time of shipment.
When producing Rose products, these volume parts are imported and used after receiving inspection (iQC).

There may be a certain amount of analog error, so if you are inconvenienced, please contact the dealer where you purchased the RA280 and they will
We will review the extent and take prompt action.

#3

Thank you for your response.

I understand there is some tolerance, and this is fine.

When brand new the RA280 had good/quiet noise tolerance with the volume control part. My concern is that only after a week or so, that tolerance started to drop massively - perhaps the part is not sealed properly and normal dust particles can get it too easily.

I will try and take video and share.

#4

Hi, please see the video. video link
Is this normal? I turned off the amplifier and moved the volume control 30 times end to end to try and clear it, it helped a bit, but next day it’s back strong again - I feel it’s getting worse as time goes.

I’m concerned this happened so quickly (2 weeks brand new amp), what will happen 2 months/years down the line? The scratchiness is creeping now toward 9-10 o clock. It bothers me when i listen to quiet passages of music and change the volume

I also noticed similar issue with another demo unit I was testing. Is this a bad batch problem perhaps?

Perhaps I need to give it some more time, maybe the noise will settle…

  • I have other amplifiers that I use with the same speakers that exhibit 0 volume self noise like this, so I can exclude my source/speakers from the problem.
#5

@lime

We apologize for any inconvenience caused.

I checked the video you sent.
With the RA280 turned off, turn the volume from 9 o’clock to Max dozens of times to see if the sliding noise is reduced.
If there is no improvement, contact the distributor in the country where you purchased the RA280 and have the volume knob replaced.