aleph p1.7 - help on single ended use

[pamaz]

hi guys.
Can somebody of you clarify if (and why ) is not recommended to ground the unused output of an Aleph P1.7 when used in Single ended mode.
The question is raising after a problem on using an apox1 volume control at an aleph P1.7 clone. Due to the volume design seems that the only way to work properly in SE is shorting to ground the unused output (-out in my case).
thanks for any sugggetsion you'll post.

Bye. Paolo

[Nelson Pass]

There shouldn't be an operational difference with one output
grounded or not, as long as it's on the outside of the output
capacitor. There is a slight qualitative difference resulting from
grounding one output, as that transistor experiences a
different load line (less voltage variation), and I leave it to you
to decide which you prefer.

[pamaz]

Hello Nelson, and thanks for your reply.
I've been thinking all day long at this thing and, always keeping in mind the use of the apox1 volume system, i've figured out that such volume is acceptable ONLY for a balanced input power amp.
The reason is that with such a volume at low volume settings, i.e. high loads of the volume board, the two sides of the preamp have a different gain, being just one side loaded with the input of the power amp, and being the impedance of the volume of the same magnitude of the impedance of the Power amp.
Therefore, I think I'll try a dummy load (that replicates the input impedance of the power amp) to the unused side of the pre output, so to give the preamp a completely symmetrical load.
Probably this sounds crazy, but I would be curious to know if somebody else has experienced heavy distosions at low volume levels by using the apox1 volume control with a 5K resistor set in an unbalanced setup.
Thanks and bye.

Paolo

]