Best strategy to convert Aleph 3 to monoblock - diyAudio
Go Back   Home > Forums > Amplifiers > Pass Labs

Pass Labs This forum is dedicated to Pass Labs discussion.

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 22nd April 2012, 11:49 PM   #1
Sony is offline Sony  Europe
diyAudio Member
 
Join Date: Sep 2004
Location: Europe
Default Best strategy to convert Aleph 3 to monoblock

The idea is to convert a pair of stereo Aleph 3 into two monoblocks.

I was wondering if I could just isolate one channel's output stage's transistors and wire them in parallel into the other channel, thus getting an output stage of 4+4 transistors instead of 2+2. I think this may be a light mod that just involves rewiring and minor resistor changes. See diagram below.

Do you think this would work or there might be a better solution?
One one hand I would be 'throwing away' most of the components of one channel per amplifier, but perhaps this could provide a cleaner result than possible alternative solutions? (I mean same sonic purity and more power than a single Aleph 3)

What values would you recommend for R1 and R2?

Thanks and regards.
Attached Images
File Type: jpg Aleph3 as mono.jpg (91.5 KB, 136 views)

Last edited by Sony; 22nd April 2012 at 11:53 PM.
  Reply With Quote
Old 23rd April 2012, 12:17 AM   #2
diyAudio Member
 
jacco vermeulen's Avatar
 
Join Date: Oct 2004
Location: At the sea front, Rotterdam or Curaçao
Send a message via Yahoo to jacco vermeulen
For more output power you'd need to swap the transformer and lytic caps for higher voltage ones.

For more output current, just run both channels in parallel.
__________________
2015 : World Cup Cat Hacky Sack
  Reply With Quote
Old 23rd April 2012, 01:53 AM   #3
The one and only
 
Nelson Pass's Avatar
 
Join Date: Mar 2001
Quote:
Originally Posted by jacco vermeulen View Post
For more output current, just run both channels in parallel.
  Reply With Quote
Old 23rd April 2012, 05:53 AM   #4
Zen Mod is offline Zen Mod  Serbia
diyAudio Member
 
Zen Mod's Avatar
 
Join Date: Jan 2003
Location: ancient Batsch , behind Iron Curtain
with mono input to paralleled channels , off course
__________________
my Papa is smarter than your Nelson !
clean thread; Cook Book;PSM LS Cook Book;Baby DiyA ;Mighty ZM's Bloggg;Papatreasure;Papa...© by Mighty ZM
  Reply With Quote
Old 23rd April 2012, 07:59 AM   #5
diyAudio Member
 
KatieandDad's Avatar
 
Join Date: Nov 2011
Location: UK
All the IRFPs in the upper half of the circuit need to be matched for Vgs with each other as do the lower ones.

Two halves of two amplifiers (stereo) will not necessarily be matched.

The bias remains the same for each MOS-FET as you increase the number of devices unless you wish to reduce it.
  Reply With Quote
Old 23rd April 2012, 09:06 AM   #6
diyAudio Member
 
KatieandDad's Avatar
 
Join Date: Nov 2011
Location: UK
Just paralleling the MOS-FETs wont increase the power with the same rail voltage.

You can bridge the amps of course.

What you can do, after re-matching up the relevant MOS-FETs is convert the Aleph 2 to an Aleph 4. This will need a new mains transformer and higher voltage caps as well as a few minor changes to component values.
  Reply With Quote
Old 23rd April 2012, 06:51 PM   #7
Sony is offline Sony  Europe
diyAudio Member
 
Join Date: Sep 2004
Location: Europe
Thanks for the answers!

My intention was to keep the chassis and major parts unchanged.
So, if adding more MOSFETs in parallel (with unchanged voltage) won't provide more power I discard my suggestion.

I was a bit reluctant in connecting each amp in parallel (with no further changes), however given the reputed opinions and consensus I will give it a try! If they explode or something I will post back.

Meanwhile I have checked the DC offset and it stays between 10 and 30mV on the four channels, which I suppose to be low/safe values...

Do you think the paralleled version will work well on a 8 ohm load? (which would be equivalent to have a single Aleph running 16 ohm) or a 4 ohm load would be preferable?
  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
Problem with one Aleph 2 monoblock Lucas_G Pass Labs 39 27th March 2012 05:49 PM
convert aleph 2 to pre for f4 slr 5000 Pass Labs 3 9th September 2010 09:54 AM
convert aleph 2 to aleph j slr 5000 Pass Labs 7 1st June 2010 12:27 AM
convert aleph 5 to 2 slr 5000 Pass Labs 0 16th September 2009 08:43 AM
My first Aleph 4 Monoblock :-) Smithers Pass Labs 14 19th January 2004 01:12 PM


New To Site? Need Help?

All times are GMT. The time now is 09:44 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