John Curl's Blowtorch preamplifier - Page 102

EUVL · 27th April 2006, 09:09 AM

PCB without heatsink.

EUVL · 27th April 2006, 09:10 AM

An add-on servo which can be removed as desired. Circuit silimar to Uli but uses 2SA970's as diff pair.

uli · 27th April 2006, 09:16 AM

Wow, your boards look fine!

Did you ever do a comparison soundwise to the original EB116?

Uli

EUVL · 27th April 2006, 09:32 AM

> Wow, your boards look fine!

To give you another temptation (picture).

> Did you ever do a comparison soundwise to the original EB116

a) I never built the original EB circuit.
b) It is not yet finished (remote control); and I have all the patience in the world. So no listening tests as yet.

I am sure someone else might even beat me to First Sound.
Richard ?

: )

Patrick

Upupa Epops · 27th April 2006, 09:34 AM

Very elegant case, Patrik

...

EUVL · 27th April 2006, 10:09 AM

Patri(c)k with c, as they spell in Britain.

: )

Upupa Epops · 27th April 2006, 10:15 AM

I'm sorry ...

Patrick is in czech Patrik...

EUVL · 27th April 2006, 10:46 AM

Just an additional remark :

At hindsight, I would probably reduce resistor values and bias the first stage also at say 8mA. The Dual FETs should cope without problems, and they operate then in the more linear region.

And I do not entirely agree with Uli that folded cascode is one gain stage. But then it is a matter of opinion, and we do not have to agree.

: )

Patrick

jbaudiophile · 27th April 2006, 11:55 AM

Hello, EUVL

Very impressive work indeed... Congrats !

I love your paralleled Jfets heatsink... And I also think that it was home made... BTW I had a similar but simpler work I stopped because of heatsink unavailability (50 paralleled !!!).

The idea was borrowed from an Italian amp that used over 100 small TO92 transistors to run a low power amp... But still curious on how you made it (drill + halfmoon grinding ?).

Anyway, thanks for sharing good pics !

Jbaudiophile

EUVL · 27th April 2006, 01:00 PM

> I love your paralleled Jfets heatsink

Only heat distributor. The heatsink is over the entire board and also contact the test of the TO92 transistors on the top surface.

They are manufactured using CNC wire-cut EDM, then black anodised. I have access to a very well equipped industrial workshop.

Patrick

27th April 2006, 09:16 AM	#1013
uli diyAudio Member Join Date: Dec 2002 Location: Vienna, Austria	Wow, your boards look fine! Did you ever do a comparison soundwise to the original EB116? Uli __________________ 'Jazz is not dead, it just smells funny' F.Zappa

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

27th April 2006, 09:34 AM	#1015
Upupa Epops diyAudio Member Join Date: Aug 2003 Location: Prague,Czech Republic	Very elegant case, Patrik ...

27th April 2006, 10:09 AM	#1016
EUVL diyAudio Member Join Date: Oct 2003	Patri(c)k with c, as they spell in Britain. : )

27th April 2006, 10:15 AM	#1017
Upupa Epops diyAudio Member Join Date: Aug 2003 Location: Prague,Czech Republic	I'm sorry ... Patrick is in czech Patrik...

27th April 2006, 10:46 AM	#1018
EUVL diyAudio Member Join Date: Oct 2003	Just an additional remark : At hindsight, I would probably reduce resistor values and bias the first stage also at say 8mA. The Dual FETs should cope without problems, and they operate then in the more linear region. And I do not entirely agree with Uli that folded cascode is one gain stage. But then it is a matter of opinion, and we do not have to agree. : ) Patrick

27th April 2006, 11:55 AM	#1019
jbaudiophile Account Disabled Join Date: Apr 2004 Location: Cysoing, near Lille	Hello, EUVL Very impressive work indeed... Congrats ! I love your paralleled Jfets heatsink... And I also think that it was home made... BTW I had a similar but simpler work I stopped because of heatsink unavailability (50 paralleled !!!). The idea was borrowed from an Italian amp that used over 100 small TO92 transistors to run a low power amp... But still curious on how you made it (drill + halfmoon grinding ?). Anyway, thanks for sharing good pics ! Jbaudiophile