95dB = 
You can run a stock SEWA 
24V would be ideal (18VAC trafo, loads down to 22,5V) for 4 ohm. With 2A bias it can do 8W. I would probably adjust the bias up a notch (as much as the heatsinks can take) 2,5-3A would be nice 3A will give you about 13W.
22,5V, 3A=67,5W => 0,4C'W heatsink.
With the IRFP250 you could get away with a 0,5'C/W (actual) heatsink, but it will be hot; 60'C
But the mosfet will stay happy @ 67,5/2 x (0,65+0,35 (al-oxide washer+grease)) +60=34+60=94'C junction temp.
You can run a stock SEWA 24V would be ideal (18VAC trafo, loads down to 22,5V) for 4 ohm. With 2A bias it can do 8W. I would probably adjust the bias up a notch (as much as the heatsinks can take) 2,5-3A would be nice
3A will give you about 13W.22,5V, 3A=67,5W => 0,4C'W heatsink.
With the IRFP250 you could get away with a 0,5'C/W (actual) heatsink, but it will be hot; 60'C
But the mosfet will stay happy @ 67,5/2 x (0,65+0,35 (al-oxide washer+grease)) +60=34+60=94'C junction temp. 
to Parafeed or Not to Parafeed that is..........
This post is an example of parafeed, http://www.diyaudio.com/forums/showthread.php?postid=986565#post986565
Parafeed is feeding a transformer through a capacitor and loading the plate with an inductor, not allowing the DC current through the transformer
Here is a little light reading on the subject from Steve Bench
http://members.aol.com/sbench/outstru.html
Ryssen said:
Just out of curiosity,do you have a schema how to do?Never done such a thing before.
This post is an example of parafeed, http://www.diyaudio.com/forums/showthread.php?postid=986565#post986565
Parafeed is feeding a transformer through a capacitor and loading the plate with an inductor, not allowing the DC current through the transformer
Here is a little light reading on the subject from Steve Bench
http://members.aol.com/sbench/outstru.html
My long term plan is to build a bi- or tri-amped system
So here is the deal
To be able to use SEWA I could build BOZ as pre, and have multiple outputs - one with fixed full gain fore SEWA, and others with adjustable gain
Main attennuator on input could be a seperate TVC or simply a build in att
PROBLEM ? I recall to have read that PASS pre need main attennuator on output, with regards to stability ?
Comment on this, please
So here is the deal
To be able to use SEWA I could build BOZ as pre, and have multiple outputs - one with fixed full gain fore SEWA, and others with adjustable gain
Main attennuator on input could be a seperate TVC or simply a build in att
PROBLEM ? I recall to have read that PASS pre need main attennuator on output, with regards to stability ?
Comment on this, please
Mad_K said:
8W
An externally hosted image should be here but it was not working when we last tested it.
http://perso.orange.fr/jm.plantefeve/sche.html
Hi Mads!
Could you tell me the voltage values in your BOZ? I mean the measured values on the Gate and Drain? (and on the Source too.)
A friend of me has some problem and it would be help for him.
Maybe He will write here him self too.
And one question from me: could you draw or show me a cascoded source follower circuit? Just to see how is it looks like. I have never seen any....
Maybe it would be a good starting point to build something with my power Jfets.
Greets:
Tyimo
Could you tell me the voltage values in your BOZ? I mean the measured values on the Gate and Drain? (and on the Source too.)
A friend of me has some problem and it would be help for him.
Maybe He will write here him self too.
And one question from me: could you draw or show me a cascoded source follower circuit? Just to see how is it looks like. I have never seen any....
Maybe it would be a good starting point to build something with my power Jfets.
Greets:
Tyimo
Tyimo said:Hi Mads!
And one question from me: could you draw or show me a cascoded source follower circuit? Just to see how is it looks like. I have never seen any....
Maybe it would be a good starting point to build something with my power Jfets.
Greets:
Tyimo
From Nelson's cascode article, Fig.7b
Attachments
driver stage
Hi
I'm thinking of adding a driver stage for SEWA.
The plan is to combine BOZ preamp and the SEWA
by removing some parts near the connection.
That is, removing output capacitor of BOZ (which is mod to have 15.5V output DC voltage),
and removing input bias network for SEWA (R1,R2,R3,R9,R10,C2...).
Directly couple the input signal to Q1's G Pin
Any comment for this?
Hi
I'm thinking of adding a driver stage for SEWA.
The plan is to combine BOZ preamp and the SEWA
by removing some parts near the connection.
That is, removing output capacitor of BOZ (which is mod to have 15.5V output DC voltage),
and removing input bias network for SEWA (R1,R2,R3,R9,R10,C2...).
Directly couple the input signal to Q1's G Pin
Any comment for this?
Maybee this could be sommething:http://www.diyaudio.com/forums/showthread.php?s=&threadid=85727
I thougt of using 6c45,but changed my mind am going to try with a CF and a ECC86 before it..
I thougt of using 6c45,but changed my mind am going to try with a CF and a ECC86 before it..
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