Hi John,john curl said:
DC servo the power amp. Would you also DC servo the source/s?
Have you followed Tom Gootee's thread on DC servos? Any comment you want to add over there?
Hi Mr John,
Thank you for your respond I hope you dont mind to answering some basic question from me ?
Ok I like to ask another question to you ?
if you dont want to must use MOSFET or JFET (+/- 50 volt or more ) in final stages what your preferences
Thank you for your respond I hope you dont mind to answering some basic question from me ?
Ok I like to ask another question to you ?
if you dont want to must use MOSFET or JFET (+/- 50 volt or more ) in final stages what your preferences
There are only three choices: JFETs, MOSFETs, and bipolars...unless you want to use tubes, but that's another matter entirely. JFETs are limited as to current and moderately limited in how much voltage they can take. There are MOSFETs that can take hundreds of volts, but the SOA will limit how much current you can run through them. Bipolars face the same restrictions--at higher voltages, you can't get much current out of them.
There are power JFETs, but at present they are only available as N-ch devices and are severely voltage limited. Unless you intend to cascode them, they are not going to work with 90V rails.
Why are you fixated on 90V rails?
Grey
There are power JFETs, but at present they are only available as N-ch devices and are severely voltage limited. Unless you intend to cascode them, they are not going to work with 90V rails.
Why are you fixated on 90V rails?
Grey
Mr Gr
Thank you for respond,
again my question based from what Mr John have said before or from what he has achieve, why +/- 90 Volt ? thats what PARASOUND JC1 brochure told.
thank you
Thank you for respond,
again my question based from what Mr John have said before or from what he has achieve, why +/- 90 Volt ? thats what PARASOUND JC1 brochure told.
thank you
John uses bipolar output devices in the JC-1.
As for why use 90V rails...it's a question of how much power you want. Like I said before, your design process is to determine the load and how much power you want into that load. Everything else falls out from those two decisions.
Grey
As for why use 90V rails...it's a question of how much power you want. Like I said before, your design process is to determine the load and how much power you want into that load. Everything else falls out from those two decisions.
Grey
Rembulan, it is difficult to design an amp with +/- 90V supplies. As an amateur, it is best to work below +/- 50V. It takes experience, engineering, and electronic 'safe area' monitoring to do it safely and trouble free.
I like servos. I make designs that will track any input for a small offset voltage correction. I don't see Tom's input.
Hi John,
DC servo thread here
http://www.diyaudio.com/forums/showthread.php?postid=1283350#post1283350
I see DxV started it not Tom, sorry.
DC servo thread here
http://www.diyaudio.com/forums/showthread.php?postid=1283350#post1283350
I see DxV started it not Tom, sorry.
I don't know about any sound differences.
Simple servos are possible, especially with this amp.
Simple servos are possible, especially with this amp.
john curl said:
correctly re-executing servos always seems to bring positive sonic change to the table. The mission for measurement diehards, if they choose to accept it, is why this occurs --- if the differences are unmeasureable.
New layout coming
I have checked the board. It needs about 10-12 updates.
http://www.datasheetcatalog.com/datasheets_pdf/B/D/1/3/BD139.shtml
I have checked the board. It needs about 10-12 updates.
http://www.datasheetcatalog.com/datasheets_pdf/B/D/1/3/BD139.shtml
Hi guys,
Can I build this amp with 2SK170 BL and 2SJ74 BL at the front end and with MJ15003 and MJ15004 at the final? The schematic i got from PMA JC-3 simulation file.
Dear Mike, will you please help me make a lay out for me, because your last lay out of this amp using dual transistors 2SK389 and 2SJ109.
Thank you gentlemen,
cheers,
Can I build this amp with 2SK170 BL and 2SJ74 BL at the front end and with MJ15003 and MJ15004 at the final? The schematic i got from PMA JC-3 simulation file.
Dear Mike, will you please help me make a lay out for me, because your last lay out of this amp using dual transistors 2SK389 and 2SJ109.
Thank you gentlemen,
cheers,