Yet another amp - simple inverted with 10x gain, mosfet output stage - Page 8 - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State

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
Reply
 
Thread Tools Search this Thread
Old 29th March 2012, 04:38 PM   #71
mikelm is offline mikelm  England
diyAudio Member
 
Join Date: May 2003
Location: England
Send a message via Yahoo to mikelm
Well, I guess would only ever be a Power I2V converter but I didn't get around to it yet.

I have two amps a loudspeaker to build first.

Have to say purely as a symmetrical amp the SSA captured my imagination.

But ur design did seem most happy when fed with current.

I'll let you know . . .
  Reply With Quote
Old 29th March 2012, 05:07 PM   #72
sonnya is offline sonnya  Denmark
diyAudio Member
 
sonnya's Avatar
 
Join Date: Oct 2001
Location: Denmark
I am not going to say anything bad on the SSA.

But i helped one building it (His own design) and i used ~40 hours on it. Before getting it stable.

I am not a fan of it, but it is new thinking and that i like a lot!
  Reply With Quote
Old 29th March 2012, 05:17 PM   #73
mikelm is offline mikelm  England
diyAudio Member
 
Join Date: May 2003
Location: England
Send a message via Yahoo to mikelm
yeah - I'm bumped into that also and didn't fix it yet - that design does "sail close to the wind" but I have the feeling that it will be worth it in the end.

It was the same with my DC linked version of Fetzilla but it came out very nice once I figured it out.
  Reply With Quote
Old 29th March 2012, 05:54 PM   #74
sonnya is offline sonnya  Denmark
diyAudio Member
 
sonnya's Avatar
 
Join Date: Oct 2001
Location: Denmark
This is going to turn.

We did get it safe, and the sound from it is true "current feedback" profile.

But you are right: the feedback makes it unsuitable for I2V powerbuffer.

I know that Andrej has it running with only +/-20mV drift. I dont knowwhat he did to make that stable, other thenm adding a cascode stage so that the VAS BJT's was less subjected to delta temperature and therefore a more stable vbe drop which again leeds to a more stable idle current.

Secondly he has degraded the VAS stage with 100K||100K.

I would really like to see some "real life" thd figures from it. But i suspect that with this VAS stage degeneration of ~50K it will be quite high.

Third: his gain is down to 16x where we used 21x

Fourth: his idle current is lower in every stage. Therefore less temp. changes in the BJT's

Without the VAS cascode and VAS degeneration we was down a drift of +/-50mV after adding a current source to the inputstage instead of emitters resistors (He fixed this problem more or less with an 1.5K NTC)

After adding a servo the drift is down to +/-1mV.

For the last version of my circuit (the last one in this thread) i got really low THD above CLASS A level, by adding a buffer stage before the mosfets. And it is 1/5 of the idle current in the mosfets.

This will be send to production next week.
So end next week i will have the PCB's up and running.

What i hope for this design is that i get really low THD of 0.006% just before clipping . But measurements will tell there story of it.
  Reply With Quote
Old 29th March 2012, 08:47 PM   #75
sonnya is offline sonnya  Denmark
diyAudio Member
 
sonnya's Avatar
 
Join Date: Oct 2001
Location: Denmark
Updated schematic with buffer.

Per sim it is stable into 8R||10uF.

The bandwidth is hitting 2MHz.

But to be that fast, a perfect layout is very important.
Attached Files
File Type: pdf simpleamp v11 noninverted 290312.pdf (16.3 KB, 270 views)
  Reply With Quote
Old 30th March 2012, 08:08 AM   #76
mikelm is offline mikelm  England
diyAudio Member
 
Join Date: May 2003
Location: England
Send a message via Yahoo to mikelm
Thx for the update - I will make ur changes in spice and check it out
  Reply With Quote
Old 30th March 2012, 09:15 AM   #77
diyAudio Member
 
Join Date: Mar 2004
Location: Krakow
Quote:
Originally Posted by kenpeter View Post
Like soOOOo. Or not?
It was interesting what Kenpeter proposed, I tried this and here are the results. Not bad at all... at 180mA idle works well too...
Attached Images
File Type: jpg sch.jpg (100.0 KB, 300 views)
File Type: jpg sine.jpg (98.9 KB, 264 views)
File Type: jpg four.jpg (99.3 KB, 248 views)
Attached Files
File Type: asc sonya kenpet inp.asc (6.6 KB, 19 views)
__________________
regards, Pawel
  Reply With Quote
Old 30th March 2012, 12:26 PM   #78
sonnya is offline sonnya  Denmark
diyAudio Member
 
sonnya's Avatar
 
Join Date: Oct 2001
Location: Denmark
See the difference to my version. There is 30dB less on second and third harmonic.
Attached Files
File Type: pdf simpleamp v11 noninverted FFT 1K 8W 8R take 290312.pdf (175.0 KB, 113 views)
  Reply With Quote
Old 30th March 2012, 12:31 PM   #79
diyAudio Member
 
Join Date: Mar 2004
Location: Krakow
Quote:
Originally Posted by sonnya View Post
See the difference to my version. There is 30dB less on second and third harmonic.
hm, you have hf switching hiss. it is -180db down @10MHz
in Kenpeter's proposition there is no HF hiss from >10KHz

but anyway I like you project very much
__________________
regards, Pawel
  Reply With Quote
Old 30th March 2012, 01:30 PM   #80
sonnya is offline sonnya  Denmark
diyAudio Member
 
sonnya's Avatar
 
Join Date: Oct 2001
Location: Denmark
Quote:
Originally Posted by padamiecki View Post
hm, you have hf switching hiss. it is -180db down @10MHz
in Kenpeter's proposition there is no HF hiss from >10KHz

but anyway I like you project very much
My design switches more aprubt than with bipolar.

My gain is 10x higher also
  Reply With Quote

Reply


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


Similar Threads
Thread Thread Starter Forum Replies Last Post
Simple stereo gain stage ss007 Analog Line Level 156 23rd August 2013 03:52 PM
Wanted: Zero feedback 2-10x gain line stage...prefer symmetrical Ric Schultz Analog Line Level 14 26th February 2011 07:26 PM
Voltage gain stage for Non-NFB MOSFET current amp gripracer Solid State 50 23rd October 2009 02:37 AM
AMP with inverting output stage mosfet fab Solid State 112 28th January 2007 04:32 AM
Elektor op-amp front-end with mosfet CF output stage Dusk Elektor 1 5th April 2006 04:09 AM


New To Site? Need Help?

All times are GMT. The time now is 11:07 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2