About Luxman M900U Measurement

[aHaidc]

Hello guys,
I found this measurement on Sound Stage Network of the Luxman M900U, the measurement stated that:

• Output noise (stereo mode), 8-ohm load, balanced inputs terminated with 600 ohms, Lch/Rch
  • Wideband: 0.532mV/0.546mV, -74.5dBW/-74.3dBW
  • A weighted: 0.164mV/0.166mV, -84.7dBW/-84.6dBW
• Output noise (stereo mode), 8-ohm load, unbalanced inputs terminated with 1k ohms, Lch/Rch
  • Wideband: 0.167mV/0.154mV, -84.6dBW/-85.3dBW
  • A weighted: 0.043mV/0.040mV, -96.4dBW/-97.0dBW

I found this was strange because the Output Noise for Unbalanced was (much) better than the Balanced. Is this normal? Or SSN has mis-typed the Balanced and Unbalanced? I read some other SSN's measurement and the Balanced were same or slightly better than the Unbalanced.
https://www.soundstagenetwork.com/i...er&catid=97:amplifier-measurements&Itemid=154

 

[dougi]

The circuit seems unusual. I thought the ODNF amp was to do with the feedback loop but it's sitting on the balance inputs.

 

[Bob from Florida]

The circuit seems unusual. I thought the ODNF amp was to do with the feedback loop but it's sitting on the balance inputs.View attachment 118842

View attachment 118842

That is the ODNF voltage regulator for the ODNF circuit just to the right of the ODNF Regulator box. Luxman sums the Balanced inputs back into single ended - that part is not shown in the Schematic posted.