900W H-class PA Amp with Limiter - Page 5 - 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 8th March 2010, 11:38 PM   #41
wg_ski is offline wg_ski  United States
diyAudio Member
 
Join Date: Oct 2007
Quote:
Originally Posted by apexaudio View Post
This circuit is for example not for DIY.
That doesn't mean it can't be done.... An experienced enough DIYer can follow an example and make it work. Usually, out of what he has on hand.

The circuit looks to me like a Crest front end, Dirty Harry's output stage, and QSC-type rail switches (they would have used 2117's if they were available way back when they did the MXa series).


The buffered 311's are plenty fast enough for rail switch drivers. QSC intentionally keeps the slew rate down to about 30V/us on the rails, because it's less prone to misfiring or other misbehavior. You can still do that with a 2117. A high speed circuit is much much much more sensitive to layout and produces weird unexpected failures. Dissipation goes up somewhat at 20kHz if you slow the switches down, but trust me you don't want to put 3kW into a compression driver. It's too loud, painful, and costs money.
  Reply With Quote
Old 9th March 2010, 12:09 AM   #42
diyAudio Member
 
andrewlebon's Avatar
 
Join Date: Feb 2008
hi wgski
greetings no i want to make the 900 watt one pure coincidence yesterday i found
your cascode zip looks very powerfull is there any pcb pattern for it even your amplifier
in casing looks powerfull one with 3 transformers and blue caps how many watts is it please
thanking you
andrew lebon
  Reply With Quote
Old 9th March 2010, 12:13 AM   #43
diyAudio Member
 
apexaudio's Avatar
 
Join Date: Feb 2010
Location: Serbia
Like Crest front, and Crest output stage...
QSC MX3000a
Attached Images
File Type: jpg mx3000aa.jpg (697.8 KB, 5840 views)
  Reply With Quote
Old 9th March 2010, 01:52 AM   #44
diyAudio Member
 
apexaudio's Avatar
 
Join Date: Feb 2010
Location: Serbia
APEX H750 with 2kVA transformer, 8x10000uF/63V single fan cooling after 3 years work in PA.
Attached Images
File Type: jpg 9932_1181834480075_1654605665_465550_3145469_n.jpg (54.3 KB, 4877 views)
File Type: jpg P1010423.JPG (713.8 KB, 4314 views)
  Reply With Quote
Old 9th March 2010, 07:29 AM   #45
diyAudio Member
 
Join Date: Dec 2005
Location: silang, cavite
Send a message via Yahoo to audiomachines
very interesting rail switching scheme, I was planing to employ your rail switching scheme on this amplifier, this one has a rail voltage of 0, +/-75VDC, +/-150VDC roughly 1000W at an 8 ohm load. too many parts I guess.
Attached Files
File Type: pdf class h pa.pdf (81.4 KB, 3298 views)
  Reply With Quote
Old 9th March 2010, 02:00 PM   #46
wg_ski is offline wg_ski  United States
diyAudio Member
 
Join Date: Oct 2007
Quote:
Originally Posted by andrewlebon View Post
hi wgski
greetings no i want to make the 900 watt one pure coincidence yesterday i found
your cascode zip looks very powerfull is there any pcb pattern for it even your amplifier
in casing looks powerfull one with 3 transformers and blue caps how many watts is it please
thanking you
andrew lebon
That's not a low-dissipation amplifier (just class AB not H). I built three of them, but the PCBs were hand-drawn directly on Cu-clad so not too reproducible. They were 1500W at 2 ohms and would melt the plugs off the extension cord. I have since been working on class H, TD, and D designs, with several class H in various states of completion. I have PCB designs for 2 and 3 rail class H amps - I have 8 of these board populated, but the rest of the chassis are still being built.
Attached Images
File Type: png KC_4kw.PNG (48.3 KB, 4280 views)
  Reply With Quote
Old 9th March 2010, 02:28 PM   #47
wg_ski is offline wg_ski  United States
diyAudio Member
 
Join Date: Oct 2007
Quote:
Originally Posted by audiomachines View Post
very interesting rail switching scheme, I was planing to employ your rail switching scheme on this amplifier, this one has a rail voltage of 0, +/-75VDC, +/-150VDC roughly 1000W at an 8 ohm load. too many parts I guess.
That one does have too many parts. A spearate commutating diode for each output????? That seems silly.

One other problem with that design is that the switch driver transistors are going to run out of gas. The voltage drop in the divider string will become excessive resulting in a loss of potential output at low Z. Either use a triple for more gain or boot strap it so it can go a little above the rail and use MOSFETs for drivers.
  Reply With Quote
Old 9th March 2010, 07:27 PM   #48
diyAudio Member
 
apexaudio's Avatar
 
Join Date: Feb 2010
Location: Serbia
Quote:
Originally Posted by audiomachines View Post
very interesting rail switching scheme, I was planing to employ your rail switching scheme on this amplifier, this one has a rail voltage of 0, +/-75VDC, +/-150VDC roughly 1000W at an 8 ohm load. too many parts I guess.
To many, and not adequte parts(2SA1943/2SC5200) and circuit for this power (Wg-ski) , see Crest 9001. IRF540 (Vds 100V) can rail 75V (Mackie SWA1801) but you must use all parts double at list and MJL4281A/MJL4302A in output stage.
  Reply With Quote
Old 9th March 2010, 08:09 PM   #49
diyAudio Member
 
Join Date: Apr 2007
Hello apexaudio

Any special reasons to use a design with BJT transistors and not Mosfet for the output transistors of your APEX H900 amp ?

Thank

Bye

Gaetan
  Reply With Quote
Old 9th March 2010, 11:03 PM   #50
wg_ski is offline wg_ski  United States
diyAudio Member
 
Join Date: Oct 2007
Quote:
Originally Posted by apexaudio View Post
but you must use all parts double at list and MJL4281A/MJL4302A in output stage.
No, you use MJL21193/4/5/6. Double the SOA of even the 4281. And no, I don't give a darn if the switchoff distortion is a little worse because of the "low" fT. It's a kilowatt PA amp, not something for a critical listening room. The commutation noise from the class H stages will far outweigh crossover distortion unless it's grossly underbiased. So use those big honkin' Motorolas and be done with it.

See Crest CA18. The original parts are 10 MHz fT (not 30,40,50 or 80) and can be replaced quite well with MJL21193's.

It is also typical of amps operating from +/-140V upper rails to use only six C5200's. See RMX5050.
  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
Nakamichi PA-7 & PA-5 Bias Setting? sourceoneaudio Solid State 6 8th March 2012 12:37 PM
900w amp module for sale nigelwright7557 Swap Meet 0 9th July 2009 11:05 PM
About a very very simple class D PA amp gaetan8888 Class D 8 13th March 2009 02:21 PM
Class-d for a 1kw PA amp MikeHunt79 Class D 4 30th December 2007 06:19 PM
200w Amp + 900w Sub = explosion? 56k Warning Daemonicus Subwoofers 2 31st May 2006 04:30 AM


New To Site? Need Help?

All times are GMT. The time now is 09:23 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