Aleph 1.2 - diyAudio
Go Back   Home > Forums > Amplifiers > Pass Labs
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

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
Thread Tools Search this Thread
Old 14th November 2005, 02:53 PM   #1
torsom is offline torsom  Norway
diyAudio Member
Join Date: Nov 2005
Default Aleph 1.2

I am going to bulid a Aleph 1.2. I have bought
Heatsinks H=50cm L=30cm W=4cm.
2 X 4KVA /45 Volt transformer.
12 x 100000uF Evox REFA
4 x 68 A 600V Bridge Rectifier
50 X IRFP 240(Same production)
Solen Capacitors
Tantalm resistors
And so on!

I am planing to reduce the 1.5 ohm resistor that is placed on the drain of IRFP 240 to 1.2 ohm. I am doing this so I can get even more out of this already powerful amplifier.

Is there anybody that have any experience in doing so?

Best regards Torsom
  Reply With Quote
Old 14th November 2005, 11:07 PM   #2
diyAudio Member
Join Date: Feb 2001
Location: Columbia, SC
You won't get more power out of an Aleph by reducing the Source resistor (I am assuming that you meant Source resistor, as there is no resistor on the Drain of the output devices)...unless you are using a low impedance load. The power into 8 ohms will remain the same. Increasing the bias can make it sound better, however. I have a pair of Aleph 2s running at roughly 10% higher bias than stock and they sound quite nice.
If you want to increase the amp's power into 8 Ohms, you'll need to increase the rail voltage. Yes, it can be done, but you'll have to pay close attention to the thermal dissipation of the MOSFETs.

  Reply With Quote
Old 15th November 2005, 05:44 AM   #3
jleaman is offline jleaman  Belgium
Join Date: Apr 2002
Send a message via AIM to jleaman
why do yoneed so much power ? I'm running 4 aleph mini's witch = 15watts each Class a.. ANd have tons od power WHY do you need a aleph 1.2 plusmore power ? Do you really have so much money to run them and the hydro bill up. ? Do yo have huge huge huge heat sinks ?
  Reply With Quote
Old 15th November 2005, 05:28 PM   #4
torsom is offline torsom  Norway
diyAudio Member
Join Date: Nov 2005
Thanks for correcting me GRollins! Yes, I meant the source resistor.
Ok! So reducing the resistor vil mostly cause higher thermal dissipation and maybe better sound.
I got the tips from KRISTIJAN KLJUCARIC, maybe i misunderstood him. He talked about 900W and right below 8A BIAS. I guess he meant 900 W in heat dissipation.
And when I think about it, as long as you have the same voltage and the same impedans(load) the effect will be the same. Ohms lov

And for "jleaman"! You asked me if I need the extra power. No! I don't need it. Somethings you just do for the fun of it and the satisfaction of getting things to work. And about the money! It's an expensive hobby and I hope I don't blow all the MOSFET's

Best regards Torsom
  Reply With Quote
Old 15th November 2005, 08:45 PM   #5
diyAudio Member
Join Date: Feb 2001
Location: Columbia, SC
So long as you go into it with realistic expectations, chances are that everything will turn out just fine.

  Reply With Quote
Old 18th January 2006, 10:31 PM   #6
folkeb is offline folkeb  Norway
diyAudio Member
Join Date: Jan 2006
Location: Trondheim
I'm in the process of finding appropriate heatsinks for the aleph 1.2. If I'm not mistaken I am also thinking of having heatsinks just on the sides. However, I've been troubled with getting the C/W ratio low enough. I figure I can have the amps running at 35 degrees above idle, but only a few, and very expensive heatsinks, can give me these low numbers and only just. We're talking about a two heatsinks for $800 (500 mm W, 200 mm long and 85 mm high).

The question is this: Have you calcultated the temp for the heatsinks under normal operation, and if so - where can I get these heatsinks?!?
  Reply With Quote
Old 18th January 2006, 11:39 PM   #7
diyAudio Member
Join Date: Feb 2001
Location: Columbia, SC
I sidestepped the whole problem. Fooey on convection heatsinks. I went water-cooled for my big Alephs. Works wonders and it's much, much cheaper than buying a zillion dollars worth of heatsinks.
I did a thread on this a couple of years ago if you're interested. Bang on the search feature a while and it'll turn up.
If you decide to go with normal air-cooled heatsinks, you might want to consider fans. It'll help keep your costs down. If you don't want to use fans, then you'll be spending a lot of money. That's just the way things are, I'm afraid.

  Reply With Quote
Old 19th January 2006, 07:16 AM   #8
Anvil is offline Anvil  Finland
diyAudio Member
Join Date: May 2003
Location: Oulu
Hi. Look from elfa, they have austerlitz heatsinks, KS300.6 might be good for you.
  Reply With Quote
Old 19th January 2006, 11:58 AM   #9
diyAudio Member
Join Date: Oct 2002
Location: Holland, The Hague
Four Seifert KL273 or something like that
Is that all there is?
  Reply With Quote
Old 12th February 2006, 01:56 AM   #10
diyAudio Member
Join Date: Oct 2005
I'm also planning to build a pair of Aleph 1.2 to use with the Apogee Diva's. It'll be my first DIY project though.

Can someone (Torsom ?) email me your parts list ? Any rough indication of how much the parts only will cost ? (besides the PCB's from KRISTIJAN KLJUCARIC).

I've considered smaller Alephs, but the Diva's are power hungry and quite inefficient (3 ohms, 87 db). I'm currently using the Diva's with a Krell KSA-200S, but would like to bi-amp. The Krell's bass is excellent, but the MRT could be improved. I've read wonderful reviews about the Aleph's MRT sweetness (a recurring trait since earlier designs such as the STATIS). So, I'm keen to give it a try and hope that it won't cost too much
  Reply With Quote


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
First version Aleph 0 (Null, ZERO, O, Os, 0s) versus later Aleph versions tiefbassuebertr Pass Labs 24 14th May 2017 11:03 AM
Aleph (Single Ended) + Larvadin (no Memory Distortion) = Ultimate Aleph? tiefbassuebertr Pass Labs 19 25th January 2014 02:15 AM
Mini Aleph Board & Aleph 2 Parts List gpsmithii Pass Labs 3 16th January 2010 03:58 AM
First version Aleph 0 (Null, ZERO, O, Os, 0s) versus later Aleph versions tiefbassuebertr Pass Labs 0 6th August 2009 11:11 AM
PCBs for Aleph 2, Aleph 3, Aleph 4 and Aleph 5 amplifiers kristijan-k Swap Meet 64 12th September 2002 07:55 AM

New To Site? Need Help?

All times are GMT. The time now is 10:09 AM.

vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright ©1999-2017 diyAudio

Content Relevant URLs by vBSEO 3.3.2