Aleph-X builder's thread. - Page 62 - 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 7th March 2005, 01:49 AM   #611
diyAudio Member
 
GeorgeBoles's Avatar
 
Join Date: Mar 2004
Location: Australia
Default How to archive big threads

Dear All

Just a quick question (3 questions):

1. I would like to sit and mull over the "Aleph X thread" and archive it. There are only 2700 posts after all.

When I hit the "Show Printable Version" and then "Show all 2689 posts on one page", the system seems to time-out or something about 1/3 through the process leaving me a blank page.

Is it possible to do this, or am I asking too much.

2. Also, is there a way when using "Show Printable Version" to get the thumbnails and/or images to show up.

3. Of course, if there is a way of archiving the whole lot in the "normal" view, e.g. by showing all posts rather than 10 per page, that would do also.

Regards and thanks,
George.

PS Didn't post on that thread, because it might just have started up again, and I have now downloaded the 50 pages at 50 posts per pages in html format! So now, this question is for future reference.
  Reply With Quote
Old 21st March 2005, 09:20 PM   #612
lcleven is offline lcleven  Canada
diyAudio Member
 
Join Date: Feb 2005
Location: Winnipeg
Default 40 Watt Aleph-X

I am starting to build the standard 40 watt version of the Aleph-X and am looking for a CRC power supply schematic. I believe I will need (for stereo) a 500VA transformer with +12v, -12v independant secondaries, about ten (10) 10,000uf electrolitic capacitors, a CL-60 thyrister to reduce power surge at turn-on, and four 6A fast recovery rectifying diodes. The case is under construction. The heat sinks are large enough for a 100 watt version if I decide I need more power later. I am going to use this amp to power the midrange speakers in a four way active crossover system. Comments and suggestions on the power supply and for building the standard 40 watt Aleph-X amp are much appreciated. Thanks

Larry C
  Reply With Quote
Old 24th March 2005, 03:29 AM   #613
diyAudio Member
 
mpmarino's Avatar
 
Join Date: Jun 2004
Location: Crunchville, where I don't fit in.
Hello,

Some of you may have seen me be a real pain in the but trying to get my Aleph 30 up and running, thank you to all who helped; I learned a lot. I got it up 'ok' right some time after I received Kari's boards. The boards are so nice it made me realize all I had done was make a me a mess that made music. I'm not satisfied with myself, ime for a better project. Not to mention my toroids have a little buzz.

The transformer I plan on using is here:
I've got this transformer.....check it out!
The thing is really quite large and can deliver WAY more than any amp would need (almost any).

I am proposing a separate 'universal' power supply to run my Pass amps now and in the future. How about a chassis containing this transformer. Have maybe six power outputs (+ 0 - on each output..each output will run an amp). Each output having its own bridge and capacitor bank. Room would be left for a Resistor or Inductor on each rail right before it exits. The monoblocs will be tied with an imbilical cord of maybe 12/3 or 10/3 SJ type cable(maybe smaller if the cable were to be some of the resistor in a crc!). Within the monobloc there will also be local capacitance similar to what is provided in the power supply.

Reasoning:
I am effectively creating a crc or clc (long range). I can modify voltage to a certain extent on a pair of pw/sup outputs to suit a particular amp. I would expect output to be ~ +-27v prior to any resistor or choke using my 20v secondaries.

I have some nice heat sinks to make some cute 3 or 4 sided mini aleph 3 type chassis' at about 8" x 8" x 7" high all sink.

Perhaps an AX for the midbasses and a A30/Mini A (briangt) for the tweets....and room for a couple more later.

Am I losing my mind here?
__________________
Crazy Yankee.
  Reply With Quote
Old 24th March 2005, 03:40 AM   #614
jleaman is offline jleaman  Belgium
Banned
 
Join Date: Apr 2002
Send a message via AIM to jleaman
You want to use that transformer for a mini a ?
  Reply With Quote
Old 24th March 2005, 03:46 AM   #615
diyAudio Member
 
mpmarino's Avatar
 
Join Date: Jun 2004
Location: Crunchville, where I don't fit in.
Ha ha..I think you misunderstood me! The way you put it made me laugh out loud it seems so rediculous. Yes, a mini a may be part of the system (an a30 makes more sense though voltagewise)...along with much more SIMULTANEOUSLY. Kind of a 'modular' approach with room to grow.
__________________
Crazy Yankee.
  Reply With Quote
Old 24th March 2005, 07:58 PM   #616
The one and only
 
Nelson Pass's Avatar
 
Join Date: Mar 2001
For Class A amplifiers a universal supply could be made by
specifying the transformer for the highest likely voltage, and
then trying placing an inductor in series with the primaries to
lower the voltage (improving the power factor) and with low
dissipation losses.

  Reply With Quote
Old 24th March 2005, 09:32 PM   #617
diyAudio Member
 
mpmarino's Avatar
 
Join Date: Jun 2004
Location: Crunchville, where I don't fit in.
Quote:
For Class A amplifiers a universal supply could be made by........
Thanks Nelson,

From what I read in your post, I am actually proposing something that will work!
__________________
Crazy Yankee.
  Reply With Quote
Old 6th April 2005, 05:10 PM   #618
protos is offline protos  Greece
diyAudio Member
 
protos's Avatar
 
Join Date: Mar 2002
Location: Athens+Addis Ababa
I have noted in some previous posts that in my case the absolute DC offset is very difficult to adjust.It starts off around 3v and needs around 1 and half hours before it stabilizes very slowly to +- 200mv.If I open the top of the case to adjust then the temp change immediately affects the offset so I am chasing it around.In fact just leaving the top panel open is enough to affect offset by a couple of volts.I guess that maybe my difference is that I doubled the bias on the diff pair so maube that is why it is so sensitive.That is all I did- the rest is standard.But still I cannot believe thatl just a couple of degrees of temperature can affect the operation of a circuit that much.It is like hyper sensitive thermometer.
The good thing is that relative offset is always not more than 50mv.
However I always worry that the amp might drift too much because of various factors such as mains voltage , room temperature etc. and sometimes this has been the case.
I think the effect is mainly because of the diff pair ccs mosfet destabilising with very small temp changes.
What are your experiences and what is the solution?
  Reply With Quote
Old 6th April 2005, 08:54 PM   #619
The one and only
 
Nelson Pass's Avatar
 
Join Date: Mar 2001
There are numerous ways to stabilize the absolute DC offset,
but the easiest is to load each output to ground with a resistor.

In any case, the issue is usually reduced maximum output when
the absolute DC is more than a volt off. 200 mV is better than
you generally need.
  Reply With Quote
Old 6th April 2005, 09:20 PM   #620
lcleven is offline lcleven  Canada
diyAudio Member
 
Join Date: Feb 2005
Location: Winnipeg
Protos,

I believe Grey recommended the two mosfets be mounted back to back (and insolated with mica pads) to a large piece of aluminum, not a heat sink per se, but just something to give the pair some thermal stability.


The Rest of you out there,

Still haven't heard from anyone who has built the stock X and what they may want to share with the rest of us. Doesn't look like there are many working Aleph X's out there as yet. Maybe a dozen or so?

Well anyway, I am forging ahead. I decided to go with a dual power supply and have purchased two Hammond 300VA, 12 volt torroids. As of now, I have built the two power supplies as C only, each with ten 4,900uf caps. I may add chokes later if the ripple is too high. I have read Nelson's tutorial on mosfet matching which is my next task. I purchased twenty IRFP044 and twenty IRFP9610, mosfets. Each type is from the same manufacturing lot. I have a question on this. Do I just match the gate turn on voltage or should I match the transconductance as well? Which way these mosfets used - common source, common drain or common gate?

Larry
  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 08:27 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