Aleph 2 transformer advice

cowanrg · 10th September 2002, 06:50 AM

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.

kristijan-k · 10th September 2002, 07:26 AM

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

skaara · 10th September 2002, 07:30 AM

38V that will become 53V... isnt that a bit too much or the voltage falls so much?

fcel · 10th September 2002, 11:32 AM

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.

marjan · 10th September 2002, 12:12 PM

Well, I do use 33 0 33 1,5kW, and my reading on DC rails is 44,3V+-
rgds
Marijan

Peter Daniel · 10th September 2002, 02:04 PM

Maybe because you are using 1.5kW, with 1kW the drop might be bigger.

cowanrg · 10th September 2002, 04:39 PM

hum, plitron only sells them in 38V outputs? how hard is it to undo a couple windings?

would i be ok with 38V?

yldouright · 10th September 2002, 04:47 PM

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.

fcel · 10th September 2002, 04:49 PM

Add inductors ... unwinding wires is just too much work and I don't think it's fun!

cowanrg · 10th September 2002, 04:57 PM

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.

10th September 2002, 06:50 AM	#1
cowanrg diyAudio Member Join Date: Apr 2002 Location: Lafayette, CO	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.

10th September 2002, 11:32 AM	#4
fcel diyAudio Member Join Date: Sep 2001 Location: LA County	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.

10th September 2002, 02:04 PM	#6
Peter Daniel diyAudio Member Join Date: Jul 2002 Location: Toronto, Canada	Maybe because you are using 1.5kW, with 1kW the drop might be bigger. __________________ www.audiosector.com “Do something really well. See how much time it takes. It might be a product, a work of art, who knows? Then give it away cheaply, just because you feel that it should not cost so much, even if it took a lot of time and expensive materials to make it.” - JC

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10th September 2002, 07:26 AM	#2
kristijan-k diyAudio Member Join Date: Mar 2002 Location: CROATIA	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

10th September 2002, 07:30 AM	#3
skaara diyAudio Member Join Date: Jun 2002 Location: Europe, Slovenia	38V that will become 53V... isnt that a bit too much or the voltage falls so much?

10th September 2002, 12:12 PM	#5
marjan diyAudio Member Join Date: Jul 2002 Location: slovenija	Well, I do use 33 0 33 1,5kW, and my reading on DC rails is 44,3V+- rgds Marijan

10th September 2002, 04:39 PM	#7
cowanrg diyAudio Member Join Date: Apr 2002 Location: Lafayette, CO	hum, plitron only sells them in 38V outputs? how hard is it to undo a couple windings? would i be ok with 38V?

10th September 2002, 04:47 PM	#8
yldouright diyAudio Member Join Date: Aug 2002 Location: New York, NY	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.

10th September 2002, 04:49 PM	#9
fcel diyAudio Member Join Date: Sep 2001 Location: LA County	Add inductors ... unwinding wires is just too much work and I don't think it's fun!

10th September 2002, 04:57 PM	#10
cowanrg diyAudio Member Join Date: Apr 2002 Location: Lafayette, CO	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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