[cookiemonsteruk]

Hello, I am new on the forum and I am looking for some advice. I didn't see a more appropriate section to ask it but I hope is Ok.
My setup is Sources > BDA-1 > BP-26 > 4BSST2 > Speakers.
I noticed a volume imbalance between left and right speakers. At low volume the sound on one speaker is noticeable lower that the other. If I turn the balance know all the way to that channel and increase the volume to about one quarter, there is some distortion/crackle heard from the speaker.
I've been trying to isolate the problem. I have swapped the connection to the speakers by swapping left and right at the back of the power amplifier and the behaviour has followed the change to the other speaker. I need to be more thorough by for example bypassing the Pre-amp however so far it makes me think the problem is coming from the pre-amp.
Could I have some suggestions please as to what else to do to a) trace the part of the chain with the problem; and b) what tests to then make to have a fairly good idea what the problem with the component is.

[James Tanner]

Hello, I am new on the forum and I am looking for some advice. I didn't see a more appropriate section to ask it but I hope is Ok.
My setup is Sources > BDA-1 > BP-26 > 4BSST2 > Speakers.
I noticed a volume imbalance between left and right speakers. At low volume the sound on one speaker is noticeable lower that the other. If I turn the balance know all the way to that channel and increase the volume to about one quarter, there is some distortion/crackle heard from the speaker.
I've been trying to isolate the problem. I have swapped the connection to the speakers by swapping left and right at the back of the power amplifier and the behaviour has followed the change to the other speaker. I need to be more thorough by for example bypassing the Pre-amp however so far it makes me think the problem is coming from the pre-amp.
Could I have some suggestions please as to what else to do to a) trace the part of the chain with the problem; and b) what tests to then make to have a fairly good idea what the problem with the component is.

Hi Cookie

Make sure the switch on the back of the 4B is in the STEREO (separate) position and not MONO.

james

[Bob Stark]

If there is a toggle switch or similar on the back that points toward unbalanced or balanced on each channel, make sure they are both pointing toward what you are using.  I don't remember what my old Bryston 8B had from 15 years ago, but I know I've done this at least once on my own mono amps and what you're experiencing was the exact result.  It happened once to a friend of mine also.

Bob

[cookiemonsteruk]

Hello James, Bob,
I have checked and I don't seem to have a Stereo/Mono switch on the back of the 4BSST2. I do have two switches for Balanced/Unbalanced. They both are on the same setting, in my case Balanced. I also verified the switch for Bridged/Individual is set to Individual. As it happens, all the switches are in the upper side as they appear on my 2011 manual:



What can I check next please?

[cookiemonsteruk]

I've switched the 4B off and moved those switches down and back up a couple of times in case it needed to.
The problem is now more evident and it seems is not only one channel.
Right channel: Sound cuts off if  balance knob all the way clockwise. Otherwise still lower volume than the left channel.
Left channel: when the volume know is turned up or down, at certain places it seems to trigger the noise & crackle.
I'm really thinking there is something up with the pre-amp. I'm still investigating.

[James Tanner]

I've switched the 4B off and moved those switches down and back up a couple of times in case it needed to.
The problem is now more evident and it seems is not only one channel.
Right channel: Sound cuts off if  balance knob all the way clockwise. Otherwise still lower volume than the left channel.
Left channel: when the volume know is turned up or down, at certain places it seems to trigger the noise & crackle.
I'm really thinking there is something up with the pre-amp. I'm still investigating.

Hi

The picture shows you bare in the Bridged Mode - you need to be in the Individual.

james

[cookiemonsteruk]

I should have been clearer James. It is on the upper position for 'individual'. The picture snippet from the manual was for reference only.

[racerxnet]

If you have an extra set of cables for the Pre to the Amp, swap them out and see if the problem is resolved. You can download REW software and run a continuous tone for testing the results. Maybe try the balanced I/O and then RCA to determine if there is a difference.

MAK

[cookiemonsteruk]

Ok. I'll try to get some cables and check that, thanks Mak. I'll also do an online search fo r REW software.

[PierreB]

What is your source and have you try a different one ?
Also you have 2 pairs of output in the back of your BP-26, have you try the second one.

[cookiemonsteruk]

Thank you Pierre, I will check that too.
The sources are a Logitech touch into the DAC and a CD player into the DAC as well via BNC. The same result. I have a SACD player into The pre using analogue connection that I haven't tried yet.
I'll post back with some results.

[cookiemonsteruk]

I am happy to report that the problem seems to have gone. I used some music with just an instrument playing for some long passages to turn the volume up all the way to half and back, a few times. It tickled the condition but I let it play for a while, with the same motions on the rotor. I went back to the music it was noticed on at first and the crackle is gone and the sound is now even on both sides.
I can only think it was a mechanical issue, maybe some corrosion had built up. There is little humidity in the room and is well ventilated, with a dehumidifier for the winter that is regularly on during the night.
I normally only listen at low volume, with that volume rotor hardly being moved and definitively never until now all the way to half. It was almost worrying seeing the power conditioner showing a draw of 2 amps.
I'll keep your suggestions if the problem re-occurs.
Would it be a bad idea to squirt a little bit of electrical contact cleaner spray into it?