Old amp - speaker volume balance out

[Alexrose1uk]

Hi guys,
I've got an old Ariston 910AX being used by the family to drive a pair of Missions. I've noticed at lower volume levels, the amp output to the right speaker is louder, although this imbalance *seems* to rectify (or at least become less of an issue) at higher amp volume levels, which gives a completely off-balance sound for quiet listening.

Is this something that can be easily corrected or is it not worth me opening her up to take a look! I figure someone here might have experience of this and may have fixed it themselves before now

 

[Lowe]

Perfectly normal chap. It's just the threshold as to where the channels begin to actually work. Each channel is independent internally, and due to component tolerance levels and other imbalances these things can occur. That's why high end gear has every individual component measured, recorded and then matching values chosen for each channel.

 

[Alexrose1uk]

Is there any easy way to correct it? (I'm guessing no from the above haha)

 

[Sinopa]

It's just the volume control potentiometer (pot) out of balance at the low end of its tracks. If it was anything else the imbalance would not become less at higher volume levels.

Tracking accuracy is something you pay for in a pot. Depending on the quality of the pot used in the Ariston, a new one might cure it. With lower quality pots you may have to try several to get a good one. It's pot luck

 

[Martynt74]

It's just the volume control potentiometer (pot) out of balance at the low end of its tracks. If it was anything else the imbalance would not become less at higher volume levels.

Unless the inbalance is still there at higher volumes but due to the higher volumes filling the room more the effect is less noticeable

 

[Sinopa]

Unless the inbalance is still there at higher volumes but due to the higher volumes filling the room more the effect is less noticeable

Possible I suppose. The OP could listen to a quiet track with the volume pot set high to prove it.

I believe though that an imbalance is just as noticeable at any normal listening volume. If it's loud enough to cause your ears to clip then perhaps not.

 

[MikeHunt79]

Perfectly normal chap. It's just the threshold as to where the channels begin to actually work. Each channel is independent internally, and due to component tolerance levels and other imbalances these things can occur. That's why high end gear has every individual component measured, recorded and then matching values chosen for each channel.

It's probably just a single component that it causing this however, the dual gang pot that it used for the volume control.

Even expensive dual gang pots have have around 10% gang error, and this will be be more noticeable at lower volumes.

Stepped attenuators are nice, but you rarely see them used on commercial stuff unless you spend silly amounts of cash...

Is there any easy way to correct it? (I'm guessing no from the above haha)

Bypass the volume pot in the amp and use an external stepped attenuator.

 

[Alexrose1uk]

Thanks for the suggestions guys, I'll take a look at the weekend and see if I can see anything obviously damaged on the mainboard, and then look at picking up a replacement pot from the likes of Map*you know*.