BOSOZ Balanced Attenuator Set-up

hifimaker · 31st January 2005, 09:34 PM

I'm interested in hooking up a 24 position rotary switch based ladder attenuator to a BOSOZ for balanced out operation.

Attached is a diagram. Is it better to use 2 ladder attenuators one for each signal side, or can a person get away with using a single ladder network similar to the Pass D1?

Is there a difference in sound quality between the two alternatives? The D1 type setup is certainly less expensive.

Thank you for the help and suggestions!

-David

jh6you · 1st February 2005, 11:41 AM

As far as I understand, the volume of D1 installed between the drains of the current-to-voltage inverter is simply a variable resistor. Its value is closely related with the two 1.5k Drain resistors so that we can change the voltage occurring across the volume resistor, by adjusting the volume knob. Both ends of the volume resistor always have the same voltages but opposite polarities, and they face Gates of the buffers provided to minimize output impedance. The concept of this volume is considered quite different from the normal volumes we are using for normal preamps.

If you are going to use balanced inputs for your power amp, I would like to recommend the volume A.

Any different opinion?

jh6you · 1st February 2005, 12:41 PM

Or, if you like to try the volume B, I think that some modification is necessary.

hifimaker · 1st February 2005, 06:13 PM

Thanks jh6you for the hints.

Has anyone tried option B in the attached schematic like the D1 for either the BOSOZ or Aleph P?

Curious to see if it is posible, and what else has to be done.

Thanks!

-David

eLarson · 1st February 2005, 08:18 PM

Perhaps you will be first?

jh6you · 2nd February 2005, 03:25 AM

I would try the option B as shown below. Resistor values could be selected for the suitable amp gain and volume level. Hoping your success...

1st February 2005, 08:18 PM	#5
eLarson diyAudio Member Join Date: Aug 2002 Location: Gaithersburg, MD	Perhaps you will be first? __________________ Would a woodchuck bother to chuck MDF?

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1st February 2005, 11:41 AM	#2
jh6you Account Disabled Join Date: Aug 2002 Location: Near to the Pacific Ocean	As far as I understand, the volume of D1 installed between the drains of the current-to-voltage inverter is simply a variable resistor. Its value is closely related with the two 1.5k Drain resistors so that we can change the voltage occurring across the volume resistor, by adjusting the volume knob. Both ends of the volume resistor always have the same voltages but opposite polarities, and they face Gates of the buffers provided to minimize output impedance. The concept of this volume is considered quite different from the normal volumes we are using for normal preamps. If you are going to use balanced inputs for your power amp, I would like to recommend the volume A. Any different opinion?

1st February 2005, 12:41 PM	#3
jh6you Account Disabled Join Date: Aug 2002 Location: Near to the Pacific Ocean	Or, if you like to try the volume B, I think that some modification is necessary.

1st February 2005, 06:13 PM	#4
hifimaker diyAudio Member Join Date: Oct 2003 Location: San Jose	Thanks jh6you for the hints. Has anyone tried option B in the attached schematic like the D1 for either the BOSOZ or Aleph P? Curious to see if it is posible, and what else has to be done. Thanks! -David

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