Gain for BOSOZ

DavidMM · 16th September 2002, 07:16 PM

I am planning to build the BOSOZ. Accoring to Nelson Pass's instructions, a gain of 10dB and 1 to 2 volts output sounds the best for the balanced-in to balanced-out configuration.

Great, I understand that. I set P5 to 300 ohms and obtain a gain of 10dB.

Now, I plan on using the BOSOZ in an Unbalanced-in to Unbalanced-out manner. Now with P5 at 300 ohm, the gain drops to 3.5dB. I can get the 10dB back by lowering P5 to 80 ohms.

My question is: Does the BOSOZ in unbalanced mode also sound best with 10dB of gain and 1 to 2 volts output? And should I lower P5 to 80 to obtain this?

Nelson Pass · 16th September 2002, 07:33 PM

80 ohms is fine.

The gain drops because of losses to the bias resistance
going to the negative supply. If you bias the BSOZ with
constant current sources instead, the gain comes back
with better CMRR. This is not an issue if you are running
unbalanced to unbalanced.

16th September 2002, 07:16 PM	#1
DavidMM diyAudio Member Join Date: May 2002 Location: Boston, MA	Gain for BOSOZ I am planning to build the BOSOZ. Accoring to Nelson Pass's instructions, a gain of 10dB and 1 to 2 volts output sounds the best for the balanced-in to balanced-out configuration. Great, I understand that. I set P5 to 300 ohms and obtain a gain of 10dB. Now, I plan on using the BOSOZ in an Unbalanced-in to Unbalanced-out manner. Now with P5 at 300 ohm, the gain drops to 3.5dB. I can get the 10dB back by lowering P5 to 80 ohms. My question is: Does the BOSOZ in unbalanced mode also sound best with 10dB of gain and 1 to 2 volts output? And should I lower P5 to 80 to obtain this?

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16th September 2002, 07:33 PM	#2
Nelson Pass The one and only Join Date: Mar 2001	80 ohms is fine. The gain drops because of losses to the bias resistance going to the negative supply. If you bias the BSOZ with constant current sources instead, the gain comes back with better CMRR. This is not an issue if you are running unbalanced to unbalanced.

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