John Curl's Blowtorch preamplifier - Page 103 - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Solid State Talk all about solid state amplification.

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
Closed Thread
Thread Tools Search this Thread
Old 27th April 2006, 01:06 PM   #1021
EUVL is offline EUVL  Europe
diyAudio Member
Join Date: Oct 2003
Enough excursion to my layout.
Let's get back to circuits.

I want to refer to Richard's schematics.

Would it not be better to use a voltage reference or LED's (to replace e.g. R5) in combination with a CCS diode like J511 (to replace R1) to bias the MOSFETs ?

I expect at least better PSRR ??

Old 27th April 2006, 01:22 PM   #1022
diyAudio Member
Join Date: Aug 2003
Location: Prague,Czech Republic
What do you can extend, Patrick ? Do you know correlation between " on paper's parametres " and sound quality ?
Old 27th April 2006, 01:38 PM   #1023
diyAudio Member
bogdan_borko's Avatar
Join Date: Nov 2005
Location: serbia, zajecar
can someone give me the lik to the schematic of blowtorch preamp???
Old 27th April 2006, 01:46 PM   #1024
diyAudio Member
jacco vermeulen's Avatar
Join Date: Oct 2004
Location: At the sea front, Rotterdam or Curaçao
Send a message via Yahoo to jacco vermeulen

sticking the elektrolytics through the heatsink is funny.
I recollect that EB seems to favor fast regulation for his EB-116 lineamp too instead of CCS's. Is it me, or does it seem that CCS diodes are not in much use ?
Bogdan is even funnier, lets give him a lik.
I am going to leave such a mess when I pass
Old 27th April 2006, 01:51 PM   #1025
anatech is offline anatech  Canada
diyAudio Moderator
anatech's Avatar
Join Date: Jun 2004
Location: Georgetown, On
Hi Bogdan,
John Curl, who designed the preamp, is selling it commercially. He has stated he has no intentions of releasing the schematic. I'm sure there are unit to unit variations to compensate for component variables. I fully support John's decision to not release the diagrams for those reasons.

If you read the entire thread, there are many clues. This is more of a gift as you can apply these lessions to your own low level designs.

Read and learn.

Old 27th April 2006, 03:18 PM   #1026
uli is offline uli  Austria
diyAudio Member
Join Date: Dec 2002
Location: Vienna, Austria
Releasing the Original would make this thread boring and senseless


BTW: did anybody ever try the LSK389 type C as the 2SK389 fades away?

'Jazz is not dead, it just smells funny' F.Zappa
Old 27th April 2006, 04:29 PM   #1027
PMA is offline PMA  Europe
diyAudio Member
PMA's Avatar
Join Date: Apr 2002
Location: Prague
How about this one?
Attached Images
File Type: gif cfb.gif (6.1 KB, 1446 views)
Old 27th April 2006, 04:55 PM   #1028
diyAudio Member
jacco vermeulen's Avatar
Join Date: Oct 2004
Location: At the sea front, Rotterdam or Curaçao
Send a message via Yahoo to jacco vermeulen
Originally posted by uli
ever try the LSK389

i'm sorry, i seem to be dyslectic. Can you show the link to the LSJ109 ?
I always have that problem with P-channel fets.
I am going to leave such a mess when I pass
Old 27th April 2006, 06:12 PM   #1029
diyAudio Member
Join Date: Aug 2003
Location: Prague,Czech Republic
Be calm, Jacco, and use some " normal " one... By line level preamp, with 3-5 gain isn't noise so critical - is free, if SNR is " only " 120 dB and not 126-130 dB.....
Old 27th April 2006, 07:54 PM   #1030
plep is offline plep  Belgium
diyAudio Member
Join Date: Nov 2004
Location: brussels
Default back to the psu ...

I’m trying to put the ideas gathered here to work (serie reg + CCS + shut reg).
I still use the basic Curl follower running under switchercad. I think this circuit is both less sensitive to the psu and “harder” to the psu than the symmetric folded cascode we are talking about here. Sorry If I’m lagging ideas by Richard and allied…

How can I improve the line regulation provided by the simple shunt reg ? I imagine that higher gm transistors would help (which ones?). At about 100ma the gm of the irf640 and irf9540 are just a bit above 1S. Regulation is quite similar to the one provided by a .85ohm internal resistance voltage source.

I can obtain a slightly more linear regulation in high frequency with a small (about 470nf) in // with the reg. It also helps to eliminate the overshot one can see with square waves (I think that Richard published them a while back). Funny, John says “no cap” and he must have good reasons.

A “massive” approach to passive filtering, 3 cells composed by a 10ohm resistor and a 47000µf 1nH ESL and 3mohm ESR cap (I hope these values are realistic), provides a much higher attenuation in most of the audio frequencies and above, but this attenuation is changing with frequency and there is a severe bump at very high frequency (due to very low esr ?). I know that only the last cell is useful in term of regulation.

The active reg shines in terms of line rejection. I probably obtain one more time meaningless results because real live noise masks the simulated behaviour that lies at impossibly low levels. Anyhow, I think that the curves are interesting. For instance, you have a less acute peak in HF using 3 different caps in the passive way and you can see the interest of multiple cells.

Any help and comment gratefully welcomed.

Philippe (who as difficulties to explain himself in English and whose mail is broken :-/).
Attached Files
File Type: zip psu freq (87.9 KB, 238 views)

Closed Thread

Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

New To Site? Need Help?

All times are GMT. The time now is 01:25 PM.

vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2016 DragonByte Technologies Ltd.
Copyright ©1999-2016 diyAudio

Content Relevant URLs by vBSEO 3.3.2