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26th January 2004, 08:45 AM  #1 
diyAudio Member
Join Date: Nov 2003
Location: bolton

AlephX build help
Hi, I am sorry to trouble this forum....but I would appreciate help right through the build process..........
I am a relative newby.....regarding power amps......however I have built preamps & power supplies in the past. I want to build two mono block alephx's.......with an output of approx 60w into 4 ohms. I have downloaded the parts list but I am aware that this amp.......requires differing values of components dependinging on the setup. Please can somebody help with the component list I require..... also how many mosfets will I require per channel? what do you recommend.....and what type.....(ie IRFP240 or IRPF044????) What sort of transformer volatages am I looking at ......ie 20020 I hope there is somebody patient out there........I will be asking some pretty basic questions...... Richard Bolton UK 
26th January 2004, 09:52 AM  #2 
diyAudio Member

hi D3
The best place to start is with calculator on post #267 of the high power x thread. It would also be a good idea to spend a couple of hours reading it. AlephX: HighPower Version The yellow boxes are the variables you decide for your amplifier and it calculates what you will need. If you choose 20volt rails with 4 amps of bias, and 4 fets you will need around 15 0 15 tx for something rated factor of 3 or more, or say a 16 17 for something rated with a factor of two. With 4 fets you will dissipate 40 watts per fet which is doable i think but will need good sinking. Nelson I think in his comercial offerings likes to keep things at around 25watts per fet. A good fet is a cheap fet Irfp240, IRFP244 and IRFP044 are all good. I think mouser and digikey have good prices on these. I chose 240 for my aleps as they were cheap and did the job. BOM materials is on the thread somewhere too for other things you will need. Keep in mind you will need alot of capacitance. 100000uF per rail for two channels would not be unreasonable I wouldnt think? Good luck 
26th January 2004, 10:26 AM  #3 
diyAudio Member
Join Date: Nov 2003
Location: bolton

Help
Thanks luke.............good pointers.........still would like some guidance .........if possible......
I will give the hpower threads a good read.........I have attached my proposal for 20v rails and 8 devices per channel ..... what do you think???? Is this correct??? 
26th January 2004, 10:35 AM  #4 
diyAudio Member
Join Date: Nov 2003
Location: bolton

Help
Gorden Bennit...........right here goes....have included xls file now ....sorry

26th January 2004, 12:03 PM  #5 
diyAudio Moderator Emeritus
Join Date: Jan 2003

Hi Richard,
It appears to me you got the wrong spreadsheet. There has been some confusion recently, resulting in the posting of a wrong xlsfile. Go to the WIKI. You'll find a lot of compressed info and a correct xlsfile as well. /Hugo 
26th January 2004, 01:11 PM  #6 
diyAudio Member
Join Date: Nov 2003
Location: bolton

Help
Thanks Hugo...................really appreciate your advice.....will check it out!

26th January 2004, 03:03 PM  #7 
diyAudio Member
Join Date: Jan 2004
Location: Split

Hi Netlist...
I have problem understanding this spreadsheet … I have download X berekening v3 A and X nania v3B … O.k. in X bereking v3A which is on wiki it says voltage 20 volts bias 4 amps ac current gain 50% number of fets 8 Peak current 4 amps power 8 Ohms 64 watts power 4 Ohms 32 watts power 2 Ohms 16 watts Dissipation 160 watts Dissipation per fet 20,00 watts Transformer secondaries 15,38 volts 16,67 volts 18,18 volts 20,00 volts Transformer wattage 320 watts 480 watts Bias per side 2,0000 amps Bias per fet 1,0000 amps Resistor to bias fet 0,5000 ohm And X Nania V3b voltage 20 volts bias 8 amps ac current gain 50% number of fets 8 Peak current 8 amps peak power 8 ohms 81 watts peak power 4 ohms 128 watts peak power 2 ohms 64 watts rms power 8 ohms 57 watts rms power 4 ohms 90 watts rms power 2 ohms 45 watts Dissipation 160 watts Dissipation per fet 20,00 watts Transformer secondaries 15,38 volts 16,67 volts 18,18 volts 20,00 volts Transformer wattage 320 watts 480 watts Bias per side 4,0000 amps Bias per fet 1,0000 amps Resistor to bias fet 0,5000 ohm To me X Nania make much more sense … Diference is bias in Nania is 8A insetead 4A...So which one is correct In X berekeing , voltage X bias = 20 x 4 = 160 W disispation ??? In Nania is 20 x 8 = 160 W am I missing something ...??? Thanks Regards Josip 
27th January 2004, 10:46 AM  #8 
diyAudio Member
Join Date: Nov 2003
Location: bolton

STRANGE DISCREPANCY!!
Thanks Josip ..... I thought it strange as well......I assume as you do ......X Nania is more accurate..............I hope somebody will confirm our feelings on this
Thanks Richard Bolton uk 
27th January 2004, 11:09 AM  #9 
diyAudio Member
Join Date: Sep 2002
Location: near Milano , Italy

You are forgetting that the amp uses dual supplies, so 20V means 20+20.
Guess who is right now? Cheers Andrea 
27th January 2004, 11:46 AM  #10 
diyAudio Moderator Emeritus
Join Date: Jan 2003

Josip, Richard,
Andrea is correct. Indeed, 20V and 8A per side makes 320W because AlephX has two sides. 20V and 4A accordingly gives twice 80W meaning 160W total. The WIKIversion is the exact one, the Naniaversion includes a RMS calculation which is handy but miscalculates the dissipation. Greetings /Hugo 
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