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Old 11th November 2003, 03:06 PM   #21
rbroer is offline rbroer  Netherlands
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Quote:
Originally posted by Terry Demol

In our experience, CFP is sterile, non-CFP
sings.

WRT BC557/547 Vs 2sa970/sc2240 (BL) , you can get VG
results with 557C/547C but having checked the data sheets
of 970/2240 they DO look even better WRT Hfe linearity vs
current over a wide range, also have very low noise.
Terry
Well, I already forgot about the CFP, it sounds great in it's current implementation.

My first SE version was using BC547B initially. Later changed them for the SC's and there was some improvement.
Yep, the linear hfe range is important, datasheet show typical curves. That's exactly why I started using these bjt's.

Terry, any experiences with using darlington's as common base transistors (with some 1k between BE of 2nd bjt) ?


Quote:
Originally posted by Peter Daniel

Does that mean you are still oversampled?
Well, not really, I was just kidding
How far are you with stuffing the board ?
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Old 11th November 2003, 03:10 PM   #22
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Half way.
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“Do something really well. See how much time it takes. It might be a product, a work of art, who knows? Then give it away cheaply, just because you feel that it should not cost so much, even if it took a lot of time and expensive materials to make it.” - JC
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Old 11th November 2003, 03:44 PM   #23
Bricolo is offline Bricolo  France
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And what about the BC550C/BC560C ?
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Old 12th November 2003, 02:05 AM   #24
jcx is online now jcx  United States
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with all the concern about sufficient gain and compound transistor pairs I think the Baxendall “Super Pair” might be worth exploring in this common-base type circuit, I point to several posts of mine about it in:

http://www.diyaudio.com/forums/showt...ht=#post220909

And scrolling down to post #236 shows the VAS stage application, but is should be easy to see how to use the super pair (I think I’ve seen it called a “complementary darlington” too) in a common base or cascode type application
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Old 12th November 2003, 01:15 PM   #25
vuki is offline vuki  Croatia
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6 months ago I made similar circuit (based on Rudolf's schematic here ). I'm using it with my nonos TDA1541 dac. Transistors are BC550C/560C and I didn't install dc servo, so it has coupling caps on the outputs. It sounds much better than single ended version I had before (cleaner, smoother and punchier).
So, Rudolf's new I/V would probably work with BC's too.
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Old 12th November 2003, 02:34 PM   #26
Bricolo is offline Bricolo  France
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Quote:
Originally posted by vuki
6 months ago I made similar circuit (based on Rudolf's schematic here ). I'm using it with my nonos TDA1541 dac. Transistors are BC550C/560C and I didn't install dc servo, so it has coupling caps on the outputs. It sounds much better than single ended version I had before (cleaner, smoother and punchier).
So, Rudolf's new I/V would probably work with BC's too.
Do you use ana nalog filter?
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Old 12th November 2003, 09:13 PM   #27
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Is there any substitute to those ZTX transistors?

Bartek
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Old 12th November 2003, 09:46 PM   #28
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Quote:
Originally posted by jcx
with all the concern about sufficient gain and compound transistor pairs I think the Baxendall “Super Pair” might be worth exploring in this common-base type circuit, I point to several posts of mine about it in:

http://www.diyaudio.com/forums/showt...ht=#post220909

And scrolling down to post #236 shows the VAS stage application, but is should be easy to see how to use the super pair (I think I’ve seen it called a “complementary darlington” too) in a common base or cascode type application
Hi jcx,

Beautiful little circuit and a great way to get around miller c
modulation (with V) induced distortions.
I actually thougt it up some time ago trying to find a way
to lower distortions I was measuring on open loop
stuff workig into med to high Z's (around 10~20k)
The two mechanisms I isolated were modulating miller
C with swinging voltage and non linear Hfe causing an
"error" current out the base. This pair lowers both by
near the Hfe of 2nd tranny.
I figured this arrangement was used somewhere, and then
just recently saw your posts... good stuff.
As you ave stated, not used much, maybe people don't fully
understand it's true virtues!

This is the great thig about discrete design, we have all these
elements at our disposal to use exactly where/how we want.


Cheers,

Terry
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Old 13th November 2003, 04:19 AM   #29
Pedja is offline Pedja  Serbia
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Quote:
Originally posted by jcx
with all the concern about sufficient gain and compound transistor pairs I think the Baxendall “Super Pair” might be worth exploring in this common-base type circuit, I point to several posts of mine about it in:

http://www.diyaudio.com/forums/showt...ht=#post220909

And scrolling down to post #236 shows the VAS stage application, but is should be easy to see how to use the super pair (I think I’ve seen it called a “complementary darlington” too) in a common base or cascode type application
What I see is the one half (single end) of the traditional diamond transistor.

Pedja
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Old 13th November 2003, 05:28 AM   #30
jcx is online now jcx  United States
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super pair common base "cascode" I/V

2 & 20 KHz 1:1 2mA each

baxendall super pair harmonic & IMD > 40 dB down vs single Q
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