BOSOZ L/R imbalance problem

[hifimaker]

I'm looking for suggestions of where to start looking to identify the problem.

The right channel is slightly louder than the left channel.

I've switched cables, sources, Amp channels, attenuators, etc. and the imbalance remains consistent with the same channel on my BOSOZ.

When connecting the BOSOZ to my Aleph30 in unbalanced mode, the left and right channels are even, and when connected in balanced mode the right channel is slightly louder.

Another interesting symptom... I started to play a CD with the BOSOZ errantly turned off, and the right channel was playing music albeit very very distorted and nothing from the left channel.

It seems like the left -(neg) phase side might be suspect.

Any ideas what I should check for?

BTW, I'm using KK's BOSOZ boards.

Thank you,

-David

[Zen Mod]

Originally posted by dw8083


BTW, I'm using KK's BOSOZ boards.



-David

and schematic is...........?

are you sure that you have right values of resistors in all positions?

I know for at least one case with KK's boards (kits) with that issue.......

[jleaman]

Originally posted by dw8083
I'm looking for suggestions of where to start looking to identify the problem.

The right channel is slightly louder than the left channel.

I've switched cables, sources, Amp channels, attenuators, etc. and the imbalance remains consistent with the same channel on my BOSOZ.

When connecting the BOSOZ to my Aleph30 in unbalanced mode, the left and right channels are even, and when connected in balanced mode the right channel is slightly louder.

Another interesting symptom... I started to play a CD with the BOSOZ errantly turned off, and the right channel was playing music albeit very very distorted and nothing from the left channel.

It seems like the left -(neg) phase side might be suspect.

Any ideas what I should check for?

BTW, I'm using KK's BOSOZ boards.

Thank you,

-David

I had this same problem when powering up my Bos Pre. It sounds like a voltage problem.. Maybe more power on the rails on the other channel ?

[hifimaker]

Originally posted by jleaman



I had this same problem when powering up my Bos Pre. It sounds like a voltage problem.. Maybe more power on the rails on the other channel ?

Thanks Jason for the tip.

I removed one of the two PSU,'s so only one PSU is driving the BOSOZ. The negative rail is -59.67 and the positive rail is 59.77

Here's a link to the schematic: http://www.kk-pcb.com/bls.html

-David

[jleaman]

Originally posted by dw8083



Thanks Jason for the tip.

I removed one of the two PSU,'s so only one PSU is driving the BOSOZ. The negative rail is -59.67 and the positive rail is 59.77

Here's a link to the schematic: http://www.kk-pcb.com/bls.html

-David

Do both Psu's show same rail voltage ?

[hifimaker]

I would think the PSU's are not the problem, since I'm only using one PSU now and the rail voltages are the same for both right and left sides.

-David

[Zen Mod]

Originally posted by dw8083
I would think the PSU's are not the problem, since I'm only using one PSU now and the rail voltages are the same for both right and left sides.

-David

do you have same voltages at 10UF-750 ohms junctions on both sides (unequal currents through halves) ?

did you matched IRFs ?
at least in channels?

[hifimaker]

Originally posted by choky



do you have same voltages at 10UF-750 ohms junctions on both sides (unequal currents through halves) ?

did you matched IRFs ?
at least in channels?

The IRF's are not matched.

Thanks Choky, you might be onto to something.

Voltages at each 10uf-750 ohms junctions:
Left side (neg): 31.165vdc
Left side (pos): 31.127vdc
Right side (neg):31.110
Right side (pos):30.789

-David

[poobah]

The Fet with the low voltage has short between drain and gate... replace it.

Edit:

or there is some junk on the circuit board...

[hifimaker]

Originally posted by poobah
The Fet with the low voltage has short between drain and gate... replace it.

Edit:

or there is some junk on the circuit board...

Thanks Poobah, I'll replace the FET. The board is clean, I'm a very good at soldiering and I cleaned the board with a flux cleaner.

I'll change the Fet and reply back.

-David