Piling up parts for an Aleph...5? - 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 10th June 2004, 12:47 PM   #1
Fuling is offline Fuling  Sweden
diyAudio Member
 
Join Date: Aug 2001
Location: Sweden (Mora)
Default Piling up parts for an Aleph...5?

Hi!

Iīm collecting parts for a new Aleph project, so far Iīve got the heatsinks, mosfets and transformers.

The heatsinks (3 pcs 75 x 16 x 6 cm) came from and old EDM and has fins on boths sides, so they need a bit of work before the mosfets can be attached. Lucky me who has a brother that works in a mechanical workshop (the same place as I got them from)

The mosfets are IRFP260N, maybe not the best choice but I bought 50 pcs very cheap on Tradera (swedish "ebay").
Plenty enough to allow tight matching I think. 6 pcs per channel should be enough.

The transformers are ham radio surplus, 2 pcs 2 x 23,5V 300VA toroids. The voltage puts me somewhere between Aleph 3 and Aleph 5, maybe some 40-50W /8 ohms.

The only thing which will cost serious money is PSU caps.
For each channel Iīm planning on using 22 000uF - choke - 47 000uF + 10 000uF per rail.
I already have the 10 000uFīs and chokes
(1,1mH 10A iron core, Iīll see if I can decrease the airgap to get a little more inductance since I donīt need 10 A DC capability per channel).

Did someone mention chassis? Well, I hate metalwork so Iīll make it as simple as possible. The heatsinks will be cut in halves and act as sides. Add some L-profiles, aluminium sheets and a wood front and weīre done. At least I hope so!
I will involve my brother as much as possible here, since he has the tools and the skills.
I made him a nice tube guitar amp a while ago so he canīt refuse to help
  Reply With Quote
Old 10th June 2004, 01:19 PM   #2
diyAudio Member
 
Join Date: Mar 2002
Don't waste your time with Aleph, go for Aleph-X,
it's just better...
But your transformer voltage may be a bit too high for that

m.
  Reply With Quote
Old 10th June 2004, 01:45 PM   #3
Fuling is offline Fuling  Sweden
diyAudio Member
 
Join Date: Aug 2001
Location: Sweden (Mora)
Quote:
But your transformer voltage may be a bit too high for that
...which is a big issue since I want to keep it cheap and new transformers would dig a hole in my budget.

What would be a good transformer for an Aleph X?
I assume my heatsinks can dissipate 150W per channel or so.

Another alternative would be a big CCS loaded source follower fed by a triode VAS. I kinda like the concept, partly because of the lack of global feedback. DC offset would be an issue here, but nothing a servo couldnīt handle I guess.

OTOH, that would be a bit too similiar to one of my current projects, a balanced choke loaded source-follower.
I donīt think I need another one of those
  Reply With Quote
Old 10th June 2004, 02:24 PM   #4
diyAudio Member
 
rwagter's Avatar
 
Join Date: Jul 2002
Location: Netherlands
Good choice,

the Aleph5 is much easier to build and stay well in reach of (somewhat) ordinairy size heatsinks. I build my Aleph5 with 2x (30*15*8.4cm) heatsink and they get really hot but not so hot you can cook an egg on them.

Your choke will drop the dc voltage even more and 23.5 is not that much for an Aleph5, I didn't use a choke/fancy rectifier or something else, just 120.000uF per channel an it works just fine.

Good luck building.
  Reply With Quote
Old 10th June 2004, 04:03 PM   #5
moe29 is offline moe29  United States
diyAudio Member
 
moe29's Avatar
 
Join Date: Dec 2002
Location: Florida
Send a message via AIM to moe29 Send a message via Yahoo to moe29
...the Aleph 5 didn't become a bad amp the day the Aleph X
was released! You won't be disappointed if you build the A5
  Reply With Quote
Old 10th June 2004, 04:21 PM   #6
diyAudio Member
 
Join Date: Mar 2002
Quote:
Originally posted by Fuling

..new transformers would dig a hole in my budget.

What would be a good transformer for an Aleph X?
I assume my heatsinks can dissipate 150W per channel or so.


you _could_ run it on 2x30V at 2.5A for 150W dissipation but your maximum output power would not be at 8 Ohm.
I'm running my (small) A-X at 2x25V and 2A, it sounds perfect, but I also should get new transformers with lower voltage for more output power (higher current).
On the aleph-x-wiki page there is a link to an excel spreadsheet which does the calculation ("AXE-1"?)
In any case you should use at least 8 transistors per channel.

that said, I don't think you will in any way be disappointed by the A5.
It's easier to build, too...
(I don't really know the A5, I changed my Aleph30 into -X)
But I don't think you couldn't handle the difficulties since I can't really follow your source followers

m.
  Reply With Quote
Old 10th June 2004, 04:32 PM   #7
Nisbeth is offline Nisbeth  Denmark
diyAudio Member
 
Nisbeth's Avatar
 
Join Date: Jan 2001
Location: Denmark
Default Re: Piling up parts for an Aleph...5?

Quote:
Originally posted by Fuling
The transformers are ham radio surplus, 2 pcs 2 x 23,5V 300VA toroids. The voltage puts me somewhere between Aleph 3 and Aleph 5, maybe some 40-50W /8 ohms.
Not sure if this matters much (or if you've already thought of it ), but if you measure 23,5V without load then the transformers are probably "only" 22V


/U.
  Reply With Quote
Old 10th June 2004, 07:46 PM   #8
Fuling is offline Fuling  Sweden
diyAudio Member
 
Join Date: Aug 2001
Location: Sweden (Mora)
I havenīt measured the transformers, but they are marked 23,5V. Strange value, but what the heck. Maybe they where custom made for something, I donīt know.

I donīt think the chokes will drop more than a volt or so, theyīre wound with about 40-45 turns of 2mm wire so the DC resistance is very low. With 22 000uF directly after the rectifier it wonīt be *that* much hum to filter out either. Not exactly a choke input filter, so to speak.
I guess the rails will end up somewhere around +-30V so it will be something in between Aleph 5 and 3.


Aleph or Aleph-X??

Well, I already have a pair of Mini-A monoblocks, built from junkbox parts, so I have an idea how the original Aleph topology sounds and this knowledge does NOT discourage me from building a more serious version!

There are more arguments for building a straight Aleph:

I fully understand the topology (at least I hope so ), and I donīt want to build somethings that I donīt understand.
Havenīt studied the X circuit closely, though.

It requires no fancy protection circuitry, nor any trimming.
(Compared to the hybrid follower I rambled about earlier, I donīt know if this applies to the Aleph-X)

Most important: I can use my stock transformers.

BTW: I have a pair of 2x12V 120VA toroids, maybe they would be more suitable in a (small) Aleph-X?
  Reply With Quote
Old 11th June 2004, 05:33 PM   #9
Fuling is offline Fuling  Sweden
diyAudio Member
 
Join Date: Aug 2001
Location: Sweden (Mora)
And... Action!

Today is the big day when my Aleph project got started!
Iīve spent a couple of hours measuring and cutting alu. L-profiles

Itīs a dirty job but someoneīs got to do it.

Next in line is drilling a bunch of holes in those profiles, marginally less tedious.

I also talked to my brother today about machining the heatsinks, and we agreed to do it next week using a wire EDM to cut them and a CNC mill too remove some of the fins where the mosfets will be attached.

Quite funny to use an EDM to cut the pieces of itīs old neighbour (the heatsinks comes from another EDM that went to kingdom come some months ago)
  Reply With Quote
Old 12th June 2004, 12:18 AM   #10
diyAudio Member
 
Join Date: Mar 2002
Good Luck!

btw. trimming the -x is not that difficult, if your parts are not completely out of match.
understanding is not so extremely difficult either (you don't have to reinvent it...)
I was forced to some understanding by the errors I made

as one should use approx. 2 times permanent power, a 120VA transformer may be a little weak for an -x. you can ask the excel sheet about that...
it would be a rather small amp I guess.

m.

p.s. no I'm not trying to talk you into anything
  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
Mini Aleph Board & Aleph 2 Parts List gpsmithii Pass Labs 3 16th January 2010 03:58 AM
WTB: Aleph parts monarodan Swap Meet 0 25th October 2006 11:04 AM
FS Aleph Parts bacworth Swap Meet 10 8th July 2005 10:31 PM
Aleph 4 parts tomchaoda Pass Labs 3 17th October 2003 01:52 AM
Aleph 5 -- Parts billy Pass Labs 2 9th January 2003 11:28 AM


New To Site? Need Help?

All times are GMT. The time now is 06:09 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright Đ1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2