:: improved hiraga 'le classe a' amp :: - 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 5th September 2002, 02:50 AM   #1
diyAudio Member
 
dhengkoel's Avatar
 
Join Date: Nov 2001
Location: CIA
Default :: improved hiraga 'le classe a' amp ::

Dear all,

I've search & read the Hiraga's archives in this forum ... I will make it one, and I came up with this schematic ... Any comment or designs you can recommend is welcome.

Thanks:
ragil.hastomo
Attached Images
File Type: jpg hiraga.jpg (65.1 KB, 792 views)
__________________
:: The last but not least ::
  Reply With Quote
Old 5th September 2002, 04:32 AM   #2
diyAudio Member
 
Join Date: Dec 2000
Location: Önnarp, Söderslätt
It looks very interesting, and I'm shure You've simulated it in PSpice.
How does it performe, phase vs. frequency response?
__________________
Regards
Hoffmeyer ;0)
  Reply With Quote
Old 5th September 2002, 10:40 AM   #3
diyAudio Member
 
Join Date: Jul 2001
Location: Orleans, France
I think the amplifier will work fine, but in a first time, without any offset automatic compensation.

As designed in your diagram, the loop gain at very low frequencies is extremely high, several millions, and will certainly cause important oscillation at subsonic frequencies. And problems occurs when the correction is feed at the input (depending on the impedance of the source) it's better to feed the correction in the feedback circuitry, or in driver stages.

You have to compute or experiment this carefully, in order to not substitute a tolerable inconvenience for a severe problem : with first choice components, and correct adjustements, Hiraga 20 W needs no offset compensation (in my opinion).

Regards, P.Lacombe
  Reply With Quote
Old 5th September 2002, 12:22 PM   #4
diyAudio Member
 
Join Date: Oct 2001
Location: Munich, Germany
Hi,

I do not want to talk you down, but I tried cascodes for some years, and while giving more treble clarity, they smeared the bass and sometimes even the midrange. I fooled myself for a long time thinking that cascodes improve the sound.

Then, the zener at 13Volt and the resistor at 20k in the emitters of the input transistors gives bad common mode behaviour, try 20 Volts and 39 to 47k, should be better. This was corrected in later schematics of the 30W super, published by L'Audophile.

BTW, the 2SC1775/2SA872 sound best at 600uAmps idling.

If you want to improve the 30W Super Hiraga, why not try this:
- feeding Q1,2 by current source

alternatively (this is heavily butchering the original circuit):
- omitting Q1,2, instead feeding correcting currents into the emitters of Q3,4 from the opposite rails

regards,
Hartmut
  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
Hiraga 30w PSU azoran Solid State 0 1st April 2007 03:32 AM
PCB Layout for Hiraga Le Classe A? ralf Solid State 18 12th November 2004 11:39 AM
Classe DR-9 lpd Swap Meet 3 19th May 2004 03:08 PM
Classé DR3 marzio70 Solid State 2 7th January 2003 09:38 PM
Classe CA-150 Super Everything Else 2 5th September 2001 03:12 AM


New To Site? Need Help?

All times are GMT. The time now is 04:11 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