Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Solid State Talk all about solid state amplification.

VSSA Circlotron
VSSA Circlotron
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
Reply
 
Thread Tools Search this Thread
Old 23rd May 2019, 02:58 PM   #151
Joe Berry is offline Joe Berry  United States
diyAudio Member
 
Join Date: Mar 2001
Location: USA
Quote:
Originally Posted by UltimateX86 View Post
Using a simple current feedback like F5 or amazingCirclotron we do not need to add a positive input or negative output voltage. What do you think ?
The F5 and Amazing Circlotron are both wonderful and justly popular class A amp projects, and I agree that simplicity is a big part of their charm. They are also well documented and proven designs, and if you use their specified components, there would be no need for concern over stability issues.

The design I proposed is not an effort to improve on them, but to pursue simplicity in a different context, namely that of a scalable high-performance class AB amplifier topology. The best choice for you may come down to your system requirements, knowledge level, and of course, aesthetic preference.

I do intend to build and document this design when time allows, and it may then become a more attractive DIY option to consider.
  Reply With Quote
Old 23rd May 2019, 03:33 PM   #152
UltimateX86 is offline UltimateX86  France
diyAudio Member
 
Join Date: Jun 2004
Location: France
VSSA Circlotron
I simulated your amp, the original with j113 at 1mA and actually it's stable on 1khz 4V square with 1uF on load

mine is a super oscillator

when you build it will be with the j113 to 1ma and irf9520 ?
Attached Images
File Type: png original.png (14.9 KB, 138 views)
__________________
I do not sell anything, I'm just trying to build a www.circlotron.audio

Last edited by UltimateX86; 23rd May 2019 at 03:38 PM.
  Reply With Quote
Old 24th May 2019, 01:13 AM   #153
Joe Berry is offline Joe Berry  United States
diyAudio Member
 
Join Date: Mar 2001
Location: USA
Is it the circuit in post #150 that is oscillating? If so, it may help to move the compensation caps. For example, you can try from collector to base of each Vas transistor, or from each Vas collector to the source of the JFET driving it.

Nothing wrong with using the self-bias connection shown there, as long as you don't mind a little DC on the output, which fortunately also lowers the JFET Vds a bit. And I think you'll still be able to drive the amp input single-ended if you want.
  Reply With Quote
Old 24th May 2019, 08:13 AM   #154
UltimateX86 is offline UltimateX86  France
diyAudio Member
 
Join Date: Jun 2004
Location: France
VSSA Circlotron
Quote:
Originally Posted by Joe Berry View Post
Is it the circuit in post #150 that is oscillating? If so, it may help to move the compensation caps. For example, you can try from collector to base of each Vas transistor, or from each Vas collector to the source of the JFET driving it.

Nothing wrong with using the self-bias connection shown there, as long as you don't mind a little DC on the output, which fortunately also lowers the JFET Vds a bit. And I think you'll still be able to drive the amp input single-ended if you want.

Hi,

Yes it is the #150, so i try 47P on Jfet source to collector, not good.

47p on base to collector seems to work, that's enough?

In fact i have a balanced output Dac/preamp so I would like use XLR on amplifier input

what I use in balanced input is good or not ? (1k 100k 100p)

thanks
Attached Images
File Type: png 47p_base_collector.png (12.1 KB, 102 views)
File Type: png collector_source.png (16.7 KB, 97 views)
__________________
I do not sell anything, I'm just trying to build a www.circlotron.audio

Last edited by UltimateX86; 24th May 2019 at 08:27 AM.
  Reply With Quote
Old 24th May 2019, 08:35 AM   #155
UltimateX86 is offline UltimateX86  France
diyAudio Member
 
Join Date: Jun 2004
Location: France
VSSA Circlotron
actually I have 433mV on two output with simple current feddback , it's bad?
__________________
I do not sell anything, I'm just trying to build a www.circlotron.audio
  Reply With Quote
Old Yesterday, 01:48 PM   #156
Joe Berry is offline Joe Berry  United States
diyAudio Member
 
Join Date: Mar 2001
Location: USA
Ideally you want minimum overshoot and ringing on reactive loads. I'm not aware of any standard for this, but I like to see no more than 20% overshoot followed by no more than 1-2 cycles of damped ringing, like the results you saw from the circuit when using my component values.

You might see improvement with your bipolar Vas by adding a resistor in series with each Vas emitter. I would try values in the 10-100 range and see if that improves square wave response. You may still need the collector-base caps, but I'm not so sure about the ones shunting the inputs.
  Reply With Quote

Reply


VSSA CirclotronHide 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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
VSSA T03 nikosokey Swap Meet 6 21st August 2014 06:46 AM
FS LC VSSA potepuh Swap Meet 2 16th March 2014 09:42 PM
VSSA 50 Idefixes Solid State 56 23rd November 2013 04:59 PM
VSSA FOR HEADPHONE bimo Headphone Systems 4 17th September 2013 01:42 AM
VSSA for sale. buzzforb Swap Meet 2 19th July 2013 03:51 PM


New To Site? Need Help?

All times are GMT. The time now is 01:49 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Copyright ©1999-2019 diyAudio
Wiki