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 25th February 2013, 09:08 PM   #1
danny92 is offline danny92  Portugal
diyAudio Member
 
Join Date: Nov 2012
Location: Lisbon
Default Types of current sources for audio amplifier applications

Hi everyone,

I'm a newbie at audio amplifiers and I'm studing in Bob Cordell's book "Designing Audio Power Amplifiers", I've only made two designs but never tested it yet.
I've a question to do:
Which is the best current source, in terms of linearity, thermal stability and output resistance?

In both books I've got from Bob Cordell and Randy Slone the best current source is allways the feedback current source, in which both transistors act together to mantain their collector currents. Another form of making a current source is using a current mirror with a known voltage and a resistor (I think that this could also be made with a wilson current mirror or enhanced current mirror), this current mirror should be degenerated with 10:1 degeneration or a little more. The other type of current source which is also an acceptable design is the current source based on diode anode-cathode (Vak) voltage, you could use normal silicon diodes such as 1N4*** series, a led or a zerner diode.

Thank you very much for your atention,
Best regards,
Daniel Almeida

Last edited by danny92; 25th February 2013 at 09:45 PM.
  Reply With Quote
Old 25th February 2013, 10:08 PM   #2
danny92 is offline danny92  Portugal
diyAudio Member
 
Join Date: Nov 2012
Location: Lisbon
Some images of the current sources.
Attached Images
File Type: png Current Sources.png (27.7 KB, 553 views)
  Reply With Quote
Old 25th February 2013, 11:15 PM   #3
Bonsai is offline Bonsai  Taiwan
diyAudio Member
 
Bonsai's Avatar
 
Join Date: Jul 2003
Location: Taipei, Taiwan
For the LTP, a simple Zener current source is the best. It can also be arranged for low(er) noise as well. For TIS load I think the two transistor variant probably the best bet.
__________________
bonsai
Amplifier Design and Construction for MUSIC! http://hifisonix.com/
  Reply With Quote
Old 25th February 2013, 11:17 PM   #4
danny92 is offline danny92  Portugal
diyAudio Member
 
Join Date: Nov 2012
Location: Lisbon
Hello Bonsai and thank you very much for your help,

I can use two feedback current sources one for the LTP and another one for the TIS, instead of zener current source for ltp and feedback current source for TIS?

Best regards,
Daniel Almeida
  Reply With Quote
Old 25th February 2013, 11:22 PM   #5
diyAudio Member
 
Join Date: Jun 2011
diytube.com • View topic - EZ Sink: Depletion-mode MOSFETs and the LM334
  Reply With Quote
Old 25th February 2013, 11:43 PM   #6
danny92 is offline danny92  Portugal
diyAudio Member
 
Join Date: Nov 2012
Location: Lisbon
Thank you very much for posting, this project with depletion-mode MOSFET seems very interesting, those CCS have very good output impedance characteristics even at higher frequencies, but I've a few questions to make:

The output current in those current sources are adjusted by the current set resistor, right?

What's the minimum current that can be set?

Whats's the minimum operational voltage?

The MOSFET draws current with the gate shorted to ground?

Thank you very much for your help,
Best regards,
Daniel Almeida

Last edited by danny92; 25th February 2013 at 11:48 PM.
  Reply With Quote
Old 26th February 2013, 04:29 PM   #7
diyAudio Member
 
indianajo's Avatar
 
Join Date: Jan 2010
Location: Jeffersonville, Indiana USA
Thanks for the review of these topologies. I had seen some of these in schematics here, wondered what they were for. My transistor books are very old. Wikipedia constant current source wasn't very useful, had one schematic, a transistor with a zener on the base leg. To keep my parts count down I ended up using JFET's with a gate tied to the source, a part which went obsolete last month, 2000 minimum.I have one J174 left. !@#$$%$^ Yes, I can buy them somewhere else, for $8-10 freight.
__________________
Dynakit ST70, ST120, PAS2,Hammond H182(2 ea),H112,A100,10-82TC,Peavey CS800S,1.3K, SP2-XT's, T-300 HF Proj's, Steinway console, Herald RA88a mixer, Wurlitzer 4500, 4300

Last edited by indianajo; 26th February 2013 at 04:42 PM.
  Reply With Quote
Old 26th February 2013, 09:44 PM   #8
Bonsai is offline Bonsai  Taiwan
diyAudio Member
 
Bonsai's Avatar
 
Join Date: Jul 2003
Location: Taipei, Taiwan
Quote:
Originally Posted by danny92 View Post
Hello Bonsai and thank you very much for your help,

I can use two feedback current sources one for the LTP and another one for the TIS, instead of zener current source for ltp and feedback current source for TIS?

Best regards,
Daniel Almeida
Of course.

The reason I like. Zener reference is tat it is extremely wide band. You do need to a. filter it and b. decouple it so that means two extra caps though.

My second favorite CCS is the two transistor active type.
__________________
bonsai
Amplifier Design and Construction for MUSIC! http://hifisonix.com/
  Reply With Quote
Old 26th February 2013, 10:03 PM   #9
diyAudio Member
 
nigelwright7557's Avatar
 
Join Date: Apr 2008
Location: Carlisle, England
I had problems with just a CCS in the tail of the LTP.
I found I had to use a current mirror too in the two legs.
Then I found I got a DC offset on the output so I made one of the current mirror resistors a preset.
__________________
http://www.murtonpikesystems.co.uk PCBCAD50 pcb design software.
  Reply With Quote
Old 26th February 2013, 10:35 PM   #10
diyAudio Member
 
Join Date: Nov 2010
Quote:
Originally Posted by Bonsai View Post
...
The reason I like. Zener reference is tat it is extremely wide band. You do need to a. filter it and b. decouple it so that means two extra caps though.

My second favorite CCS is the two transistor active type.
Someone did a series of simulations of different current sources to choose for an amp. That was you IIRC?
Did you ever compare any of the commercial CCSs? Seems like a suitable use for an IC.
Also did you miss my question on your transformer thread?
And best source of power supply capacitors -about 10000Uf 100V - to use with it?

Best wishes
David

Last edited by Dave Zan; 26th February 2013 at 10:37 PM.
  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
not typical Audio DAC-IC's for Top Class Audio Applications tiefbassuebertr Digital Line Level 13 16th December 2012 02:01 PM
Voltage Sources & Current Sources rascal101 Everything Else 3 13th September 2012 12:56 PM
List of current production types mashaffer Tubes / Valves 3 15th December 2007 05:20 PM
constant current sources... cathode_leak Tubes / Valves 10 29th March 2005 10:18 PM
Current Sources vinay Pass Labs 1 19th March 2005 04:23 AM


New To Site? Need Help?

All times are GMT. The time now is 01:39 PM.


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