John Curl's Blowtorch preamplifier part II - Page 1304

loek · 09:28 AM

Quote:

Originally Posted by Charles Hansen

And I would also be curious to see the schematic.

ƒ‰ƒbƒNƒXƒ}ƒ“Š”Ž®‰ïŽÐbƒz[ƒ€»•iî•ñbƒXƒeƒŒƒIƒpƒ[ƒAƒ“ƒvM-800A - LUXMAN
Only the pics I can understand....
Regards, Loek

john curl · 21st June 2011, 03:25 PM

So far, so good, but the 'essence is in the 'triangles'.

john curl · 21st June 2011, 05:49 PM

We need more 'info' in order to define this design.

simon7000 · 21st June 2011, 05:54 PM

John the picture looks like SIP package op amps

Johnloudb · 21st June 2011, 05:58 PM

yep, I see the little buggers, and sockets no less.

john curl · 21st June 2011, 09:39 PM

I bet they are National.

Chris Hornbeck · 22nd June 2011, 03:20 AM

Hi Ladies and Germans,

Although I'm still working my way through the 13000+ posts in Part Deux, I wonder if it's appropriate to present a circuit element derived from the famous John Curl "boxer" input stage. The circuit is a "boxer" second stage ("VAS" in op-amp speak) with its advantages, although I'm using a half circuit version for a phono equalizer.

If interested, let me know, or if OT, also let me know. I've enjoyed these two threads enormously, and much, much thanks to all.

Chris

ostripper · 22nd June 2011, 03:28 AM

Quote:

Originally Posted by john curl

I bet they are National.

Nope , toshiba custom SIP . Same as the JVC super A , custom manufactured for luxman. A good way to keep the IP secret ... put it in a proprietary IC.

OS

ThorstenL · 22nd June 2011, 03:45 AM

John,

Quote:

Originally Posted by john curl

So far, so good, but the 'essence is in the 'triangles'.

The Design is the same "Only Distortion Feedback" as the B1000.

MJ had pretty extensive articles on this. The "Op-Amp" shown is actually no op-amp, but a discrete ciruit.

The "forward" path of the Amp is a simple single ended 2-stage open loop BJT Circuit, driving one side of the output stage with high impedance.

The "Op-Amp" only receives the extracted error, amplifies it suitably and applies it to the other side of the output stage.

Both "Distortion feedback" and "Signal" are mixed at the input of the output stage.

I personally would suggest that contrary to OSTrippers comments the design is quite unusual and interesting. I can see the possibility for it to provide better tradeoffs between "zero feedback" and "ton's of feedback" without attracting the undesirable side-effects of either...

Ciao T

john curl · 22nd June 2011, 04:33 AM

I am thankful for that. I would not liked to have been passed over by an IC chip. '-)

21st June 2011, 05:58 PM	#13035
Johnloudb diyAudio Member Join Date: Feb 2008	yep, I see the little buggers, and sockets no less. __________________ My Website: Hyperacusis, Tinnitus, My Story

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read


	Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving

21st June 2011, 03:25 PM	#13032
john curl diyAudio Member Join Date: Jul 2003 Location: berkeley ca	So far, so good, but the 'essence is in the 'triangles'.

21st June 2011, 05:49 PM	#13033
john curl diyAudio Member Join Date: Jul 2003 Location: berkeley ca	We need more 'info' in order to define this design.

21st June 2011, 05:54 PM	#13034
simon7000 diyAudio Member Join Date: Nov 2008 Location: Oakmont PA	John the picture looks like SIP package op amps

21st June 2011, 09:39 PM	#13036
john curl diyAudio Member Join Date: Jul 2003 Location: berkeley ca	I bet they are National.

22nd June 2011, 03:20 AM	#13037
Chris Hornbeck diyAudio Member Join Date: May 2011 Location: Little Rock	Hi Ladies and Germans, Although I'm still working my way through the 13000+ posts in Part Deux, I wonder if it's appropriate to present a circuit element derived from the famous John Curl "boxer" input stage. The circuit is a "boxer" second stage ("VAS" in op-amp speak) with its advantages, although I'm using a half circuit version for a phono equalizer. If interested, let me know, or if OT, also let me know. I've enjoyed these two threads enormously, and much, much thanks to all. Chris

22nd June 2011, 04:33 AM	#13040
john curl diyAudio Member Join Date: Jul 2003 Location: berkeley ca	I am thankful for that. I would not liked to have been passed over by an IC chip. '-)