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6th February 2006, 09:04 PM  #101  
diyAudio Member
Join Date: Jun 2004
Location: Bern

Quote:
it's true, the value of VR101 is wrong, as it has been pointed out also in This Thread Here's a copy of my answer to that: "Hi all, that is the schematic I posted on the AlephX PCB group buy thread. It is directly taken from KK's Site and I've just redrawn it to create the PCB. Now, the value of VR101 is wrong (my BIG mistake! ), it really must be 200 Ohms, as Grey pointed out. I apologise for this mistake. As for R103, the value of 360 Ohms is exactly the same as on the original schematic I mentioned above. I do not know if it makes too much of a difference with Grey's original value of 330 Ohms. With VR101 set to 0, the equivalent value of the parallel of R103 and R104 is 203.85 Ohms with R103=360 and 193.875 with R103=330 Ohms. With VR101 set to 200 Ohms, the equivalent total resistance is respectively 255.53 and 249.1 Ohms. I leave to the experts (I'm not one) to judge whether it's preferrable to set R103 to 330 Ohms or to leave it as it is. As far as I know, several AlephX have been already built following this schematic and they work..." Here's the corrected schematic. Cheers, Bruno 

6th February 2006, 09:43 PM  #102 
diyAudio Member
Join Date: Jun 2004
Location: Bern

BOM for Main Board
Here's the BOM for the main board:

6th February 2006, 09:54 PM  #103  
diyAudio Member
Join Date: Jun 2004
Location: Bern

Quote:
the exact values of R & C on the rectifier boards depend on the diodes used, as well as on the transformer. A commonly used starting point is R=100 Ohm, C=100 nF. Jim Hagerman (Hagtech) wrote a nice tutorial about "snubbers": Snubbers As for the diodes, it depends on how much power you want to squeeze from your amp. For a low output power (2030 W), MUR1560 will be enough, otherwise better use MUR3020WT or equivalent. Cheers, Bruno 

6th February 2006, 10:16 PM  #104 
diyAudio Member
Join Date: Jun 2004
Location: Bern

Hi all again,
today I ordered a new run of corrected rect. boards. They should be at my place in approx. 3 weeks. Cheers, Bruno 
7th February 2006, 05:04 PM  #105  
diyAudio Member
Join Date: Oct 2005

Quote:
Thx very much!, i have got my boards already, they are fantastic!, but i have a question, what is the value of the resitor on the FETS board. 

7th February 2006, 08:46 PM  #106 
diyAudio Member
Join Date: Jun 2004
Location: Bern

Hi lscangus,
the source resistors are calculated as follows: R=0.5V/Bias current in each FET. This is a nice tutorial. And this spreadsheet will help you calculate all the important parameters of your AlephX. Cheers, Bruno P.S.: Lately I've been very busy with professional and private matters, and I had to put aside my hobbies (including this one) a little bit. Please bear with me, I will try to answer all your questions as soon as I can, but please, do not get upset if I happen to disappear for a day or two every now and then... 
8th February 2006, 05:18 PM  #107 
diyAudio Member
Join Date: Mar 2003
Location: Montreal, Canada

Late arriver ...
Hi carondimonio
I might be late but if I would be interested in a set of PCB's to build a stereo amp. Thanks 
9th February 2006, 07:09 AM  #108  
diyAudio Member
Join Date: Oct 2005

Quote:
What do you mean by 0.5V/bias current? Angus 

10th February 2006, 03:14 AM  #109 
diyAudio Member
Join Date: Aug 2005

it means the r value = .5 divided by the bias current at each fet. also look here
http://www.diyaudio.com/wiki/index.php?page=AlephX All the information you need should be linked to here. eric 
11th February 2006, 08:53 AM  #110 
diyAudio Member
Join Date: Jun 2004
Location: Bern

Jpnitrof,
did you get my mail? 
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