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Old 10th September 2002, 06:50 AM   #1
cowanrg is offline cowanrg  United States
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Default Aleph 2 transformer advice

hey, im building some aleph 2's and need a little help with the transformer selection.

i am looking at the plitron standard power transformer, 1.5KVA. i have 4 32,000uf caps per channel. i know the rail voltage for the aleph 2 is +-45V, but i have read of people use many different values. in this particular model, plitron carries a 38, 40, and 45V output type. which should i use? i pretty much know how the rest of the amp will work, but i am still a little unsure about the power supply part of the project. any help would be appreciated.
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Old 10th September 2002, 07:26 AM   #2
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Hello cowanrg,


If you can choose amoung the transformer values that you mentioned, then use the transformer with 38 V at seccondaries.
The 1500 VA transformer would be more than enough for the Aleph 2 amplifier.
Also, try to use inductors of 1 - 4 mH between two 32000 uF capacitors.


Best regards,
Kristijan Kljucaric
http://web.vip.hr/pcb-design.vip
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Old 10th September 2002, 07:30 AM   #3
skaara is offline skaara  Slovenia
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38V that will become 53V... isnt that a bit too much or the voltage falls so much?
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Old 10th September 2002, 11:32 AM   #4
fcel is offline fcel  United States
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Default 1.2 to 1.25 multiplier

38vX1.2=45.6v. It has been mentioned a lot of times on this forum to use 1.2 to 1.25 multiplier for real life sitauation. Square root of 2 is for ideal situation which nothing is.
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Old 10th September 2002, 12:12 PM   #5
marjan is offline marjan  Slovenia
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Well, I do use 33 0 33 1,5kW, and my reading on DC rails is 44,3V+-
rgds
Marijan
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Old 10th September 2002, 02:04 PM   #6
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Maybe because you are using 1.5kW, with 1kW the drop might be bigger.
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Old 10th September 2002, 04:39 PM   #7
cowanrg is offline cowanrg  United States
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hum, plitron only sells them in 38V outputs? how hard is it to undo a couple windings?

would i be ok with 38V?
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Old 10th September 2002, 04:47 PM   #8
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cowanrg

I believe that the production Aleph 2 used a 750VA toroids in their monoblocks with 31-0-31 secondaries. BTW, that is the size cap I am looking for too. Where did you get them and how much were they.
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Old 10th September 2002, 04:49 PM   #9
fcel is offline fcel  United States
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Add inductors ... unwinding wires is just too much work and I don't think it's fun!
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Old 10th September 2002, 04:57 PM   #10
cowanrg is offline cowanrg  United States
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yldouright:

i got them from someone in this forum, for like $80 US shipped for a total of 9 of them. maybe a little expensive, but it sure beats looking around for some...

hum, so i if the production aleph2's used 750VA, why is everyone using like TWICE that? shouldnt i be more than fine with 1KVA?

and how do inductors work? i know you add them in the cap bank, but do they reduce voltage? and if so, whats the formula to figure out what values i will need?

sorry for all the questions, but im no EE, and i searched for all of this, but its just not here, or really hidden somewhere.
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