I recently acquired a set of BrianGT Aleph boards. The most current black ones, with the nifty break-away daughterboards for the big transistors.
Photo -
As the Alephs are not the current 'super popular' project (having being supplanted by the F5 these days) the bulk of the information I can find is old, with lots of broken links and lost photos.
Also, with Brian's website have been down for some time now, there is a notable lack of information.
Does anybody have a known good schematic that works on those boards? There is room for up to 3 output devices/ current sources per channel, and it uses TO-220 size transistors for the drivers.
I seems to me that an Aleph 3 or an Aleph 5 should work, and perhaps a mini Aleph. ??
Lastly is there any good information on making an Aleph into a headphone amp, like this -- 6moons audio reviews: Reality Check with Terry Aben ?
Thank you in advance.
Photo -
As the Alephs are not the current 'super popular' project (having being supplanted by the F5 these days) the bulk of the information I can find is old, with lots of broken links and lost photos.
Also, with Brian's website have been down for some time now, there is a notable lack of information.
Does anybody have a known good schematic that works on those boards? There is room for up to 3 output devices/ current sources per channel, and it uses TO-220 size transistors for the drivers.
I seems to me that an Aleph 3 or an Aleph 5 should work, and perhaps a mini Aleph. ??
Lastly is there any good information on making an Aleph into a headphone amp, like this -- 6moons audio reviews: Reality Check with Terry Aben ?
Thank you in advance.
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6L6,
I'm in somewhat the same situation, several years ago I bought a set of BrianGT Aleph boards and I'm just now getting around to building the amp.
Two mini-aleph threads I found useful are:
http://www.diyaudio.com/forums/pass-labs/2001-mini.html
http://www.diyaudio.com/forums/pass-labs/163604-mini-aleph-power-supply.html
I attached a copy of the schematic diagram that I've been using. One thing you should be aware of is that one of the versions of the amp boards has a capacitor's polarity marked backwards on the board, I think it is C2 but you should compare with the schematic to be sure.
The parts list for the amp is still available from chipamp.com http://www.chipamp.com/diyaudio/mini-A.xls, and I've attached a parts list I found for the power supply boards.
Since the part lists were created several years ago a few of the parts are no longer available from Digikey. Here are the substitutions I made, these are not tested but as far as I can tell should work.
Amp
C5 (PS1H103G-ND) is no longer stocked, Digikey recommended P4513-ND instead.
Power Supply
D1-D4 (MUR1560OS-ND) is no longer stocked. Substituted MUR1560GOS-ND which is a RoHS replacement
Heat sink for D1-D4 (HS184-ND) is no longer stocked. Substituted HS346-ND.
I'm about to place an order with Digikey, but first I need to decide what to do with the CRC filter in the power supply. One option is to just use jumpers for R3-R12, another is to put in resistors to create a low pass filter. I posted some questions in the power supply thread I linked above, but haven't had any responses yet.
Anyway, I hope this helps get you started. Be sure to post updates as your project progresses.
- Matt
I'm in somewhat the same situation, several years ago I bought a set of BrianGT Aleph boards and I'm just now getting around to building the amp.
Two mini-aleph threads I found useful are:
http://www.diyaudio.com/forums/pass-labs/2001-mini.html
http://www.diyaudio.com/forums/pass-labs/163604-mini-aleph-power-supply.html
I attached a copy of the schematic diagram that I've been using. One thing you should be aware of is that one of the versions of the amp boards has a capacitor's polarity marked backwards on the board, I think it is C2 but you should compare with the schematic to be sure.
The parts list for the amp is still available from chipamp.com http://www.chipamp.com/diyaudio/mini-A.xls, and I've attached a parts list I found for the power supply boards.
Since the part lists were created several years ago a few of the parts are no longer available from Digikey. Here are the substitutions I made, these are not tested but as far as I can tell should work.
Amp
C5 (PS1H103G-ND) is no longer stocked, Digikey recommended P4513-ND instead.
Power Supply
D1-D4 (MUR1560OS-ND) is no longer stocked. Substituted MUR1560GOS-ND which is a RoHS replacement
Heat sink for D1-D4 (HS184-ND) is no longer stocked. Substituted HS346-ND.
I'm about to place an order with Digikey, but first I need to decide what to do with the CRC filter in the power supply. One option is to just use jumpers for R3-R12, another is to put in resistors to create a low pass filter. I posted some questions in the power supply thread I linked above, but haven't had any responses yet.
Anyway, I hope this helps get you started. Be sure to post updates as your project progresses.
- Matt
I am interested in this mod... I've always wanted to try out the "Aleph sound" but have no metalworking capabilities for large heatsinks. Maybe we can just adapt an Aleph preamp schematic for use on the boards?
This is a great thread! There is just too much information in the hundreds of pages of all the other mini-Aleph threads...
It looks like the marking for C1 on zeonrider's boards are backwards as well. According to the schematic I posted in post #2 of this thread the positive side of C1 should connect to C4 and R15. On the boards it is reversed.
While we talking mini alephs, does anybody have any input on the power supply CRC question I posted in the ps thread?
http://www.diyaudio.com/forums/pass-labs/163604-mini-aleph-power-supply-3.html
- Matt
Again:
Regards zeoN_Rider
An externally hosted image should be here but it was not working when we last tested it.
Regards zeoN_Rider
The schema that you posted actually was the origin of the mistake see:
http://www.diyaudio.com/forums/pass-labs/52188-new-aleph-mini-pcb-gb-56.html#post630253
Here are 2 more posts about fix in the new board:
http://www.diyaudio.com/forums/pass-labs/52188-new-aleph-mini-pcb-gb-102.html#post1200889
http://www.diyaudio.com/forums/pass-labs/52188-new-aleph-mini-pcb-gb-103.html#post1201252
Last post said it was corrected.
I hope this will help.
http://www.diyaudio.com/forums/pass-labs/52188-new-aleph-mini-pcb-gb-56.html#post630253
Here are 2 more posts about fix in the new board:
http://www.diyaudio.com/forums/pass-labs/52188-new-aleph-mini-pcb-gb-102.html#post1200889
http://www.diyaudio.com/forums/pass-labs/52188-new-aleph-mini-pcb-gb-103.html#post1201252
Last post said it was corrected.
I hope this will help.
Both the black and the early red boards are good for mini-A, Aleph 3/Aleph 30, Aleph 5, or Aleph 60. They share the same basic schematic but have different rail voltages and bias point and number of output devices.
Keep in mind, Brian didn't use the same part number as Papa's service manual, but it can be easily done to create a BOM for A5 using the black board parts number. Send me an email via the forum ....
Keep in mind, Brian didn't use the same part number as Papa's service manual, but it can be easily done to create a BOM for A5 using the black board parts number. Send me an email via the forum ....
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