2stageEF high performance class AB power amp / 200W8R / 400W4R

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from post1098
Quote:
Originally Posted by kgrlee View Post
Don, IMHO, this amp is the best example of Self's 'Blameless' topology.
No it's not. According to Self blame is a three stage sch.

Quote:
Originally Posted by DouglasSelf View Post
Please note that the Blameless configuration has three stages; it is the Lin that has two.
What is the argument about?
statements:
a.)
this amp is the best example of Self's 'Blameless' topology.
b.)
No it's not.
c.)
According to Self blame is a three stage sch.
d.)
Please note that the Blameless configuration has three stages;
e.)
it is the Lin that has two.

Which statement is causing the problem?
 
2 donpetru,
... If an audioamp develop DC voltage at output, dependant on output power, it must horrible distort, and you should measure it and repair this fault... it is not inherent behavior of topology.😉

Small asymmetric distortions can generate small DC offset (additionally to "normal" DC offset). Its not need to be horrible 😉. I think that for example 0,1% second harmonic can generate few milivolts additional offset (depending on output power). It may be interesting way to measure such "special" kind of distortions - just using low pass filter and DC meter.
 
Toni, please forgive the basic question but what is the signal to noise ratio of this amplifier?

Voila:

  • 20 µV - A-weighted
  • 39µV - BW 20kHz
  • 54µV - BW 80kHz
  • 117µV - Full bandwidth (~ 500kHz limit of VP-7723)
SNR in reference to 1kHz@200W@8R output level:

  • 125 db - A-weighted
  • 121 db - BW 20kHz
  • 117 db - BW 80kHz
  • 111 db - Full bandwidth (~ 500kHz limit of VP-7723)

BR, Toni
 
Attached picture from VP-7723D datasheet showing built in filters.
Maybe my fault: Is "PSOPHO A" the same as "A-weighted"?
Measured 125db not 127db. Do you mean 121 db "unweighted" should correspond with 127 db "A-weighted" otherwise the filters are not the correct ones?
BTW: the measurements are from lab setup where the cable routing was optimized. I hope but don't expect the same noise figures from the ready made amplifier - we will see soon...

BR, Toni
 

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