Nothing to see here

kenpeter · 10th July 2011, 02:40 PM

And you were expecting normal?

jez · 10th July 2011, 05:01 PM

Do you work for the Transistor Marketing Board by any chance

Ian Finch · 10th July 2011, 05:10 PM

Looks perfect for an SMD project - but what level of noise do you sim, relative to a 1V input say?

kenpeter · 10th July 2011, 06:51 PM

Quote:

Originally Posted by jez

Do you work for the Transistor Marketing Board by any chance

Yes of course, and 12R council too. Cheaper by the thousand!
All of three pennies or less at the local surplus store.

Consider 4 transistor arrays such as mmpq2907 and mmpq3906.
Especially where bonded device temps might be advantageous.

kenpeter · 10th July 2011, 07:05 PM

Quote:

Originally Posted by Ian Finch

Looks perfect for an SMD project - but what level of noise do you sim, relative to a 1V input say?

I provided the .asc file, just so you could tell me.

1V LTSpice (2VPP) input would be soft clipped by the Zeners.

kenpeter · 10th July 2011, 08:22 PM

Quote:

Originally Posted by kenpeter

Consider 4 transistor arrays such as mmpq2907 and mmpq3906.
Especially where bonded device temps might be advantageous.

Uh... I think I must have meant mmpq3904 (NPN) and mmpq3906 (PNP).
Dunno where "2907" came from?

ingenieus · 10th July 2011, 08:31 PM

Nice one. I ran it through LTspice. As far as I can tell, it is all about the soft clipping. The input stage is certainly very interesting, and I'm still trying to take it all in.

kenpeter · 04:39 AM

Nevermind soft clipping at +/-22V, and +/-6.5A,
nor a non-switching AB crossover. None of that
stuff even slightly important. The secret entirely
about rounding sharp corners off the schematic!

No-one else has figured this by now? As nature
abhors a vacuum, so too does LTSpice abhor a
sharp corner. Place an oil slick there, and watch
the electrons spin wildly out of control into the
grandstands.

I've added 22uF in series with R5, and 680R+68pF
across R8. Defining -3dB rolloffs at 5Hz and 96KHz.

Elvee · 12th July 2011, 07:07 AM

Intriguing circuit, especially the input stage.
But the performances do not seem to match the complexity however.

The input stage has a number of symetries, and by some aspects it reminds me of cross-quads, but stacked vertically.
Except there is a rather large ratio between the collector current of say Q3, Q19 and Q5, Q8 f.e.: this and the 470R coupling resistors ruin most of the Xquad effects.

What is this topology supposed to achieve, Ken? (Apart from the clipping control and Iq control, which are pretty obvious.)

dadod · 12th July 2011, 07:40 AM

Quote:

Originally Posted by kenpeter

Yes of course, and 12R council too. Cheaper by the thousand!
All of three pennies or less at the local surplus store.

Consider 4 transistor arrays such as mmpq2907 and mmpq3906.
Especially where bonded device temps might be advantageous.

Because of 12R council you have 53MHz oscilation here.

10th July 2011, 05:01 PM	#2
jez diyAudio Member Join Date: Jan 2004 Location: n.e england	Do you work for the Transistor Marketing Board by any chance __________________ Repairs and mods to Real Hi-Fi, guitar amps and P.A. in North East England. http://www.arklesselectronics.com

10th July 2011, 05:10 PM	#3
Ian Finch diyAudio Member Join Date: Apr 2010 Location: Coffs Harbour, on the east coast	Looks perfect for an SMD project - but what level of noise do you sim, relative to a 1V input say? __________________ regards

11th July 2011, 04:26 AM	#8
kenpeter diyAudio Member Join Date: Nov 2007 Location: Dallas	Nevermind soft clipping at +/-22V, and +/-6.5A, nor a non-switching AB crossover. None of that stuff even slightly important. The secret entirely about rounding sharp corners off the schematic! No-one else has figured this by now? As nature abhors a vacuum, so too does LTSpice abhor a sharp corner. Place an oil slick there, and watch the electrons spin wildly out of control into the grandstands. I've added 22uF in series with R5, and 680R+68pF across R8. Defining -3dB rolloffs at 5Hz and 96KHz. Last edited by kenpeter; 11th July 2011 at 04:39 AM.

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10th July 2011, 08:31 PM	#7
ingenieus diyAudio Member Join Date: Apr 2011	Nice one. I ran it through LTspice. As far as I can tell, it is all about the soft clipping. The input stage is certainly very interesting, and I'm still trying to take it all in.

12th July 2011, 07:07 AM	#9
Elvee diyAudio Member Join Date: Sep 2006	Intriguing circuit, especially the input stage. But the performances do not seem to match the complexity however. The input stage has a number of symetries, and by some aspects it reminds me of cross-quads, but stacked vertically. Except there is a rather large ratio between the collector current of say Q3, Q19 and Q5, Q8 f.e.: this and the 470R coupling resistors ruin most of the Xquad effects. What is this topology supposed to achieve, Ken? (Apart from the clipping control and Iq control, which are pretty obvious.)

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