AVR 350 Unbalanced Surround Channels.

peter-d-w

Active Member
I have just bought an old AVR 350 through the Classified Forum. There is a 4db difference between the LS and RS speaker outputs as measured by a Sound Pressure Meter App on my tablet. There is less output on the left channel than on the right. If I change the speakers over from L to R the L channel is still the same lower volume as before so it is not a fault with the speakers. I can compensate for the difference with the Level settings in the setup but is this cause for concern? Is this a common problem and is there a fix?
 

spl23

Well-known Member
It may well just be the acoustics of your room. Try setting both LS and RS to the same level, and measure the level of with your meter swapping the channel which is driving the speaker rather than swapping the speakers themselves over - so first connect the LS outputs to the left surround speaker and take a measurement, and then, leaving the left surround speaker in the same place in the room, connect the RS outputs to the left surround speaker and take a measurement.
 

peter-d-w

Active Member
It may well just be the acoustics of your room. Try setting both LS and RS to the same level, and measure the level of with your meter swapping the channel which is driving the speaker rather than swapping the speakers themselves over - so first connect the LS outputs to the left surround speaker and take a measurement, and then, leaving the left surround speaker in the same place in the room, connect the RS outputs to the left surround speaker and take a measurement.
Thanks, good idea, I have now tried it and the difference becomes 10dB which proves that the amp is giving 5dB less output on LR than on RR as I had to boost the LR channel by 5dB to match the RR before the swap. I have also tried a reset to defaults and that doesn't correct the issue either.
 

spl23

Well-known Member
In that case it does sound as if you have a fault.

Although one final point - what Arcam call a "dB" is no such thing; it's just an arbitrary unit they use to describe a volume setting. Don't assume that a dB measured by your meter is anything to do with a setting on the amplifier - I'd be inclined to set both channels to 0dB on the Arcam before making the measurement, just to be 100% sure.

But from what you say above, it does sound likely that one channel is misbehaving in some way - I can't off-hand think of any kind of trivial fix for such a problem, so I think you're going to need to ask Arcam for advice.
 

peter-d-w

Active Member
In that case it does sound as if you have a fault.

Although one final point - what Arcam call a "dB" is no such thing; it's just an arbitrary unit they use to describe a volume setting. Don't assume that a dB measured by your meter is anything to do with a setting on the amplifier - I'd be inclined to set both channels to 0dB on the Arcam before making the measurement, just to be 100% sure.

But from what you say above, it does sound likely that one channel is misbehaving in some way - I can't off-hand think of any kind of trivial fix for such a problem, so I think you're going to need to ask Arcam for advice.
Thanks for responding. I will email Arcam to ask for advice.
 

larkone

Member
One thing worth trying is a full software reset:

Reset procedure. Be carefull!

Press and hold RDS INFO and PRESET/TUNE both together and this will take you to the engineering menu.
Using the EFFECT button move down until you see restore settings.
Move the volume control so it displays YES
Move down again until you see EXIT then press OK
You will see RESET in the display and it will power off and on.
Note though that this resets all levels and distances back to zero so they will all need to be redone
 

peter-d-w

Active Member
One thing worth trying is a full software reset:

Reset procedure. Be carefull!

Press and hold RDS INFO and PRESET/TUNE both together and this will take you to the engineering menu.
Using the EFFECT button move down until you see restore settings.
Move the volume control so it displays YES
Move down again until you see EXIT then press OK
You will see RESET in the display and it will power off and on.
Note though that this resets all levels and distances back to zero so they will all need to be redone
Thanks, I've done that though and it made no difference.
 

larkone

Member
OK just a thought. The only other thing would be to try a software reload - the last version was v3.5 I think. Clutching at straws hear as it does sound like something needs fixing mechanically.
 

peter-d-w

Active Member
OK just a thought. The only other thing would be to try a software reload - the last version was v3.5 I think. Clutching at straws hear as it does sound like something needs fixing mechanically.
I'm on the latest firmware 3.5 already.
 

Arcam_boy

Distinguished Member
If everything else works as it should and it still sounds good then I'd be inclined to just compensate the difference on the Arcam and upping the quieter channels output until it all measures the same output on your SPL meter.
 

peter-d-w

Active Member
If everything else works as it should and it still sounds good then I'd be inclined to just compensate the difference on the Arcam and upping the quieter channels output until it all measures the same output on your SPL meter.
Everything is working fine and it sounds great. It is so much better than my Onkyo TX SR 608. I can live without the HDMI control etc. at least for the time being. I bought it on impulse as I have fond memories of an AVR 50 I had years ago. I am keeping a check on the suspect channel but on the whole I am very pleased with it.
Update : I have now stripped this down, got rid of the dust inside and redone the setup. The surround channels now balance and all is well! This is an incredible amp for its age.
 
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