a wonderfull sziklai - Page 14

Lumba Ogir · 13th January 2009, 01:09 PM

homemodder,
I comprehend.

The turn-off "artifact" is well-known, can be cured by class A biasing only.
Many buoyant attempts have been made to get rid of the unpleasant crossover distortion in other ways, unfortunately, I don`t think it`s possible.

homemodder · 13th January 2009, 02:09 PM

Cant get rid of, but can be significantly reduced, Im trying something similar now with a triple but its more tricky here because of stability problems.

Do you mean having the cfp in class a ?? I already use the cfp in class a. Look at stee s example of cfp ef.

What I dont like is the extra complexity to achieve this but it has good sonic merits, when I remove the extra circuitry the human voices seem to have like a glare at the end of a sung word and with it it dissapears, cymbals become very detailed with the extra circuitry too. When listening at 200 300 watt levels the crossover artifacts sound horrible.

Lumba Ogir · 13th January 2009, 03:01 PM

Quote:

Do you mean having the cfp in class a ?? I already use the cfp in class a.

Yes, but I expect much worse distortion for instance in the output stage.

Quote:

When listening at 200 300 watt levels the crossover artifacts sound horrible.

Along with various other artifacts.

Stee · 13th January 2009, 09:48 PM

The turn-off "artifact" is well-known, can be cured by compensation biasing only

this resistor's value are not simulated, just for example
(I'm not able to use)

sakis · 14th January 2009, 06:33 AM

at least that some forum members are
solid rock value !!!!! the ratio as we speak remains ..... one post one schematic !!!!! way to go stee !!!

i am just jocking but i think that if i ever had the time to analyze all schematics posted by stee it will take something like a year ...

thanks people

catalin · 14th January 2009, 03:13 PM

not have time for practical testing .
Thd (5khz) with 5 harm =0.0002 %
Slew rate = 250 V/uS

AndrewT · 14th January 2009, 03:36 PM

C32 is too small.
It needs to be >= 22k/680r * sqrt(2) * 4u7F >= 215uF. Use 220uF.

C42 seems a bit big @ 47pF
R = 150 at output also seems big, only 8mA passing Q60 & 51.

Does the mirror load on the LTPs work when you have dual complementary VAS?

roender · 14th January 2009, 04:00 PM

Quote:

Originally posted by catalin
not have time for practical testing .
Thd (5khz) with 5 harm =0.0002 %
Slew rate = 250 V/uS

Catalin,

May I suggest you to not reference CCS's biasing resistors to ground?
Try to make the input stage + VAS as much as possible a constant current compound stage.
Keep the ground as clean as possible and use a separated PSU for output stage, and for inputs stages a good ccs+shunt feedbackless PSU

Regards,
Mihai

homemodder · 14th January 2009, 04:24 PM

Quote:

[i]

Does the mirror load on the LTPs work when you have dual complementary VAS? [/B]

Nope, only in simulation, I hope no one tries to build it, output offset will be all over the place, the current mirror issue with complementary ltps has been discussed many times, rather try a cascode on the ltps. Do a search here of randy slones designs. He eventually had to change his current mirror designs because of this.

catalin · 14th January 2009, 04:27 PM

Quote:

Originally posted by AndrewT
C32 is too small.
It needs to be >= 22k/680r * sqrt(2) * 4u7F >= 215uF. Use 220uF.

C42 seems a bit big @ 47pF
R = 150 at output also seems big, only 8mA passing Q60 & 51.

Does the mirror load on the LTPs work when you have dual complementary VAS?

Andrew ,where do you get that calculation (>= 22k/680r * sqrt(2) * 4u7F ) ?

14th January 2009, 06:33 AM	#135
sakis diyAudio Member Join Date: Jan 2006 Location: nea makri athens greece	it is very nice to see at least that some forum members are solid rock value !!!!! the ratio as we speak remains ..... one post one schematic !!!!! way to go stee !!! i am just jocking but i think that if i ever had the time to analyze all schematics posted by stee it will take something like a year ... thanks people __________________ SERVICE ΕΝΙΣΧΥΤΩΝ ΚΑΙ ΙΑΠΩΝΙΚΩΝ ΜΗΧΑΝΗΜΑΤΩΝ ΗΧΟΥ www.eastelectronics.gr

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13th January 2009, 01:09 PM	#131
Lumba Ogir Banned Join Date: Apr 2005 Location: Stockholm	homemodder, I comprehend. The turn-off "artifact" is well-known, can be cured by class A biasing only. Many buoyant attempts have been made to get rid of the unpleasant crossover distortion in other ways, unfortunately, I don`t think it`s possible.

13th January 2009, 02:09 PM	#132
homemodder Account disabled at member's request Join Date: May 2006	Cant get rid of, but can be significantly reduced, Im trying something similar now with a triple but its more tricky here because of stability problems. Do you mean having the cfp in class a ?? I already use the cfp in class a. Look at stee s example of cfp ef. What I dont like is the extra complexity to achieve this but it has good sonic merits, when I remove the extra circuitry the human voices seem to have like a glare at the end of a sung word and with it it dissapears, cymbals become very detailed with the extra circuitry too. When listening at 200 300 watt levels the crossover artifacts sound horrible.

14th January 2009, 03:36 PM	#137
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	C32 is too small. It needs to be >= 22k/680r * sqrt(2) * 4u7F >= 215uF. Use 220uF. C42 seems a bit big @ 47pF R = 150 at output also seems big, only 8mA passing Q60 & 51. Does the mirror load on the LTPs work when you have dual complementary VAS?