(x) (x) = N_p - Page 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 18th June 2003, 11:57 AM   #41
diyAudio Member
 
macka's Avatar
 
Join Date: Dec 2001
Location: Australia
Okay ,

Here are some pics , but only from the web cam so quality is only soso, Friday night I hope to have better digital image of baby A Aleph.

macka
Attached Images
File Type: jpg babyx1.jpg (73.4 KB, 377 views)
  Reply With Quote
Old 18th June 2003, 12:00 PM   #42
diyAudio Member
 
macka's Avatar
 
Join Date: Dec 2001
Location: Australia
This is a wider shot of the baby X Aleph

macka
Attached Images
File Type: jpg babyxwide.jpg (65.3 KB, 366 views)
  Reply With Quote
Old 18th June 2003, 12:17 PM   #43
diyAudio Member
 
macka's Avatar
 
Join Date: Dec 2001
Location: Australia
Anyway you have some idea but the photos do not do justice to the effort.

The idea of design was to use a MDF base initally to build and model the construction, enabling scaling of the amp along with more heatsinks as required. Using aluminum seemed unwarranted at this stage.

I also wanted to maintain a distinct diy theme and flavour rather than a cloned re engineered outcome. I think a diy mentality is a more relaxed way of approaching the home built task, particularly as Mr Pass has commented the exact specifications and tolerances are really there to met the manufacturers advertised claims. So why bust your boiler over a few millivolts.

I put the driver board up on a centrally mounted perspex platform for several reasons, to enable easy adjustment, access for assemble / re assemble via the screw in terminal blocks, and the board is central to the box for future heatsinks.

The output stage as you may be able to see is point to point for similar reasons, so I can easily mix and match and scale the amp at this early stage. But it is delicate and I will improve on this with terminal strips to provide strain relief for the wiring.

The final tesing is done an it is completely stable, offset both absolute and Dc are only a few millivolts after 1/2 hour warm up.

Technically matching the negative drive side and the input pair seem to cure the offset ills without issue here

The DC bias is as per Greys original design at 4 1/2 amps per side

In fact I rebuilt the output with 2 pairs per side for best practice minimising wattage per device @ 14 watts each ie there are 8 output fets per channel.

Soon I will up the anti with 2 x 300 va tranni per channel for +- 25 VDC and add 2 more heatsinks for box for 300-400 watts disippation.

I expect this will be a fair comparison for the mighty Aleph 2 and will then report on the subjective outcome.

Again sorry for the poor images, there will be better ones soon
macka
  Reply With Quote
Old 18th June 2003, 12:20 PM   #44
diyAudio Member
 
macka's Avatar
 
Join Date: Dec 2001
Location: Australia
Heres the point to point output stage

macka
Attached Images
File Type: jpg babyxoutput.jpg (66.8 KB, 342 views)
  Reply With Quote
Old 18th June 2003, 12:42 PM   #45
Taco is offline Taco  Netherlands
diyAudio Member
 
Join Date: Nov 2002
Location: Place in the Netherlands
Nice job, the middle are the capacitators with on top of that the pcb?
  Reply With Quote
Old 18th June 2003, 12:46 PM   #46
diyAudio Member
 
macka's Avatar
 
Join Date: Dec 2001
Location: Australia
Yes,

They are Panasonics,

Underneath the driver platform are the Nichion 8 x 15000 63 filter capacitors, so the ripple is only about 500mv, the amp is totally silent even at point blank range.
  Reply With Quote
Old 18th June 2003, 01:01 PM   #47
diyAudio Member
 
macka's Avatar
 
Join Date: Dec 2001
Location: Australia
Sorry for the mis print.

The DC bias is as per Greys original design at 4 1/2 amps per side.

This should have read 4 1/2 amps total bias

Grataku would never forgive me ...........Muhahahahahaha

macka
  Reply With Quote
Old 18th June 2003, 03:35 PM   #48
Taco is offline Taco  Netherlands
diyAudio Member
 
Join Date: Nov 2002
Location: Place in the Netherlands
Hehe, you already stated that you have 0.5 volt over the source resistor.
  Reply With Quote
Old 22nd June 2003, 09:09 AM   #49
diyAudio Member
 
macka's Avatar
 
Join Date: Dec 2001
Location: Australia
Hello everyone,

Okay following a very busy working week I finally found the time to do some more evaluation of the X Aleph vs Aleph.

Despite not being apples for apples (in terms of power)I could not wait for the decision on resourcing a 100 X Aleph, so here are my impressions. My speakers are about 96dba so most of the time I'm using just a few watts anyway.

I used the BOSOZ with ccs (Aleph fet type) in X mode as retrofitting back to the original design is a tedious process, and I felt it would give the best performance with unbalanced inputs.(and the rails on the X Aleph are closer to 15 vdc now and current share tweeked for 50/50% ~ 1.0k...its helps).

Playing the Aleph first, I could hear the familiar engaging sound, the mids appear accentuated, lusty and warm, and the top end warm and a tad slightly recessed. The bass has plenty of ommp.

Smooth, mellow with nice imaging and a sound that can be played all day long.

Switching to the X Aleph, its hard to descibe, but the presentation is less forward in the mids, perhaps because the tops are more crisp and decisive, with a nice hint of warmth and the bass is firm and articulate.

The presentation appears to have more drive and dynamics, less oozing and more snap and bite on those transients than the Aleph.

The surprise is an marked improvement in spatial imaging and staging of instruments and solist vocals to the point where they can be quite visible. The drive, snap transparency appears to replace the warm & romantic engagement of the Aleph, and creates a new kind of excitement (of being there) that is still quite sweet.

Is it better , well if absolute realism is what your lookin for, to my ears yes.


macka
  Reply With Quote
Old 22nd June 2003, 09:21 AM   #50
diyAudio Member
 
Join Date: Apr 2002
Location: Netherlands
Quote:
Originally posted by macka
Hello everyone,

The surprise is an marked improvement in spatial imaging and staging of instruments and solist vocals to the point where they can be quite visible. The drive, snap transparency appears to replace the warm & romantic engagement of the Aleph, and creates a new kind of excitement (of being there) that is still quite sweet.

Is it better , well if absolute realism is what your lookin for, to my ears yes.


macka

I agree with you! I also found the bass has more slamm, and oompf in a nice way, it comes from nowhere and disappears as quick as it came, very spooky in a nice way... (at least with my 130W version!) ...

Edwin
  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



New To Site? Need Help?

All times are GMT. The time now is 04:38 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