Szekeres with CCS NFB? - 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 3rd August 2009, 02:27 PM   #1
diyAudio Member
 
Join Date: Jan 2008
Default Szekeres with CCS NFB?

Hi,

I have built Szekeres headphone amplifier with LM317 CCS. How do I implement the negative feedback? Should I just connect resistor after the output coupling cap back to the source of the mosfet?

Thanks.
Attached Images
File Type: gif tomo_cs1.gif (4.4 KB, 278 views)
  Reply With Quote
Old 3rd August 2009, 02:37 PM   #2
h_a is offline h_a  Europe
diyAudio Member
 
h_a's Avatar
 
Join Date: Sep 2006
Location: Graz, Austria
This is a ClassA biased source follower - that already enjoys 100% voltage feedback. Not sure, why you want more

Have fun, Hannes
  Reply With Quote
Old 3rd August 2009, 05:57 PM   #3
diyAudio Member
 
Join Date: Jan 2008
Ah, didnt know that. But it soounds there is not enough bass and trebles, it sound towards mids. So if I would like to try more gNFB should I just connect the resistor defacto across the output cap?
  Reply With Quote
Old 3rd August 2009, 06:12 PM   #4
Bigun is offline Bigun  Canada
diyAudio Member
 
Bigun's Avatar
 
Join Date: Jan 2009
Blog Entries: 2
Quote:
Originally posted by kacernator
Ah, didnt know that. But it soounds there is not enough bass and trebles, it sound towards mids. So if I would like to try more gNFB should I just connect the resistor defacto across the output cap?

I don't think that's going to work to your satisfaction. The output cap is there to ensure that only the alternating output signal finds it's way to your headphones. You don't want to be putting a resistor across it.

You could play around with some other things but with a single transistor amplifier you shouldn't expect miracles.

One thing that will have an effect on the low frequencies is the input filter of C1 and associated resistors. A larger value of C1 can improve low frequency response.

If I understand correctly the feedback is via Source degeneration - in other words it's set by the constant current source. You could put a capacitor in there, in parallel with the current source to reduce the negative feedback at higher frequencies. This might boost the treble but can also make it unstable - so you'll want to experiment.

I never saw this circuit before so hope I didn't provide some bad advice...
__________________
"The test of the machine is the satisfaction it gives you. There isn't any other test. If the machine produces tranquility it's right. If it disturbs you it's wrong until either the machine or your mind is changed." Robert M Pirsig.
  Reply With Quote
Old 3rd August 2009, 08:47 PM   #5
Banned
 
Join Date: Apr 2005
Location: Stockholm
Hi,
would this work?
Attached Images
File Type: jpg ha.jpg (29.5 KB, 206 views)
  Reply With Quote
Old 4th August 2009, 04:59 AM   #6
diyAudio Member
 
Join Date: Jan 2008
Hi,

I have solved my problem by increasing the value of output to 4700uF. (I am using 32 Ohm headphones).

Thanks for your ideas.
  Reply With Quote
Old 4th August 2009, 05:15 AM   #7
Banned
 
Join Date: Apr 2005
Location: Stockholm
kacernator,
sorry for asking, but what problem did it solve?
  Reply With Quote
Old 4th August 2009, 05:32 AM   #8
diyAudio Member
 
Join Date: Jan 2008
It solved my problem with bass response. Also overall sound is more focused, not so smeared, maybe because of better phase shifts too.
  Reply With Quote
Old 4th August 2009, 06:30 AM   #9
Banned
 
Join Date: Apr 2005
Location: Stockholm
kacernator,
simplicity is a great benefit, but this degree of simplicity is not beneficial.
  Reply With Quote
Old 4th August 2009, 06:58 AM   #10
diyAudio Member
 
Join Date: Jan 2008
I know it is not the best, but now it sounds very very good to me. I am driving it with aikido front end...really great sound. I am missing nothing in sound. Mayeb add an external EQ to compensate for not so good (cheap) headphones.

PS: I lowered the output cap to 2200uF, as 4700uF was overkill.
  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
NE5532 as a pre amp for a Szekeres headphone amp zebra100 Headphone Systems 2 1st July 2009 09:15 AM
Szekeres with IRF3205? kuroguy Solid State 10 8th May 2009 09:02 AM
szekeres amp - irf510 equivalent m0nty Solid State 7 24th August 2005 07:31 AM
DIY Power supply for a Szekeres headphone amp Bricolo Headphone Systems 93 30th November 2002 05:58 PM
Some questions about the Szekeres headphone amp: Bricolo Headphone Systems 16 25th November 2002 07:39 PM


New To Site? Need Help?

All times are GMT. The time now is 10:47 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