Brian,
In one of the previous AlephX threads you said that VM would do the quantity discount even if we wanted different output voltages. That VM was more concerned about the core size. If this is still true, the 600VA @ 2X40Vct (-20-0-+20) would be workable for stereo Aleph 3 or 30 and 500VA @ 54Vct (-27-0-+27) would work for one channel of an Aleph 5 or 60. This could bring in more orders toward the quantity discount.
What is the range of outputs that VM will accept for these orders?
Rodd Yamashita
In one of the previous AlephX threads you said that VM would do the quantity discount even if we wanted different output voltages. That VM was more concerned about the core size. If this is still true, the 600VA @ 2X40Vct (-20-0-+20) would be workable for stereo Aleph 3 or 30 and 500VA @ 54Vct (-27-0-+27) would work for one channel of an Aleph 5 or 60. This could bring in more orders toward the quantity discount.
What is the range of outputs that VM will accept for these orders?
Rodd Yamashita
roddyama said:
I will talk to John about this tommorrow. For the 500VA, it is $68 for one and $62 for 10 or more. 600VA is a few dollars more, due to the extra wire.
I will ask him tommorrow about the different voltages, and power.
I picked up a 4x25 1kVA for my Aleph5 that I am planning on building (one Aleph2 chassis for the AlephX and the other for the Aleph5 😀 )
One more thing, if we get a large order of the exact same specs for a transformer, we can get a 500VA custom one made by Plitron for about $52 each, but they all would have to be the same specs, and would have the canadian shipping charges.
--
Brian
I pick up a surplus 1000VA @ 35-0-35 from Plitron a while back. If I recall correctly, shipping was a little more then $15USD to the Detroit area. Not bad, but it could offset the price difference.
Rodd Yamashita
Rodd Yamashita
roddyama said:
Interesting. I just found their surplus page myself:
http://www.plitron.com/pages/surplus.htm
The 1.5kVA 4 x 18vac x 21A would be interesting to use if you want to make a stereo high powered aleph-x... I couldn't imagine the heatsinks, but if you went for active cooling, it would be possible.
Speaking of active cooling, are there any interesting solutions out there for high dissipation? I have a friend with a couple of intercoolers laying around from his turbo projects for his car....
--
Brian
You could also do a separate central PSU enclosure with dual amp enclosures, then the heat sinks get a little smaller per enclosure.🙂BrianGT said:
Rodd Yamashita
For forum members building the Aleph x in Australia Harbuch Electronics sell the 15+15 volt transformer @300 va for A$48.00 plus gst each, and they have them in stock at the moment.
macka
macka
transformer voltage
just some food for thought,
I´ve calculated a few PSU´s with psudesigner to see what transformer I should order for my Aleph X. With those low voltages and high currents the Vdc = Vac x 1.2-1.4 rule doesn´t work that well anymore.
For a 16v supply with a pi filter and 10A of total bias I would need a 16V transformer.
With those currents every 10th of an Ohm gives a voltage drop of 1V!
So what I would like to point out is that one should be really carefull ordering 12V trafos and such. With a healthy bias this will give only 12V dc wich will give + and - 9V output i.e. only 20watts into 8 ohms.
william
just some food for thought,
I´ve calculated a few PSU´s with psudesigner to see what transformer I should order for my Aleph X. With those low voltages and high currents the Vdc = Vac x 1.2-1.4 rule doesn´t work that well anymore.
For a 16v supply with a pi filter and 10A of total bias I would need a 16V transformer.
With those currents every 10th of an Ohm gives a voltage drop of 1V!
So what I would like to point out is that one should be really carefull ordering 12V trafos and such. With a healthy bias this will give only 12V dc wich will give + and - 9V output i.e. only 20watts into 8 ohms.
william
Yes, at 12 Vac the AC --> DC multiplier is down to 1.1 at best. Stick the inductor in there for the pi filter and 1:1 is looking quite realistic indeed.
European warning!
Reichelt has 12, 15 and 18 V at 330, 500 and even 800 VA. Prices are cheap at EUR 39 for 500 VA and EUR 56 for 800 VA.
Elfa has 12/15(only up to 300 VA)/18 up to 500 VA.
http://www.reichelt.de/
http://www.elfa.se/
Reichelt has 12, 15 and 18 V at 330, 500 and even 800 VA. Prices are cheap at EUR 39 for 500 VA and EUR 56 for 800 VA.
Elfa has 12/15(only up to 300 VA)/18 up to 500 VA.
http://www.reichelt.de/
http://www.elfa.se/
forgot another thing:
those nice ultra fast recovery diodes have a forward voltage drop of 1.4-1.7 volts (HFA08TB60).
william
those nice ultra fast recovery diodes have a forward voltage drop of 1.4-1.7 volts (HFA08TB60).
william
UrSv
The trafo`s from Reichelt seems quit leight, their 800Va weights Ca 4Kg.
I have two 800VA trafos from Toroid and they are 6Kg each.
I doubt they have the same real life spec...
The trafo`s from Reichelt seems quit leight, their 800Va weights Ca 4Kg.
I have two 800VA trafos from Toroid and they are 6Kg each.
I doubt they have the same real life spec...
I ordered 500VA transformers from Reichelt and they weigh just around 4 kilos, so I wonder how the 800VA could weigh the same. Maybe a print error? 5-6 kilos would be much more likely.
2002tii said:
I have never seen them IRL but if they state 800 VA then it should be. The 800 VA at Elfa from Toroid is listed as 11 Kg so that is at the other end of the scale.
It was a recommendation on suppliers.
I never looked at the 500VA from Reichelt, but now I see that they have the same physical measure on the 500 and 800VA trafo`s.
The measurements on the 800VA is probably wrong then...
The measurements on the 800VA is probably wrong then...
One more thing, I don`t think two trafo`s are the same just because their VA rating is the same.
What about ambient and trafo temperature when they measure it?
And for how long can it deliver 800VA before it burns?
One 800VA trafo kan be much more powerful than another 800VA trafo.
It`s kind of like comparinge two amplifiers on the backgrounds of Watts rating...
What about ambient and trafo temperature when they measure it?
And for how long can it deliver 800VA before it burns?
One 800VA trafo kan be much more powerful than another 800VA trafo.
It`s kind of like comparinge two amplifiers on the backgrounds of Watts rating...
regulate psu?
Folks,
I am aiming for the followings, please correct/steer me away from protential problems and wrong assumptions for a newbie.
Target to go for
a/ Maximum heat dissipation 180W-200W per channel ie 2 X 11" bulk buy heatsinks.
b/ 6 devices per heatsink, so appox. 30W per device
Can I use one
625VA 24-0-24 transformer with
Bridge rectifier--->C-L-C--->
and use LM388K(on big heatsink) to regulate and provide 15V to 20V per rail for the amp board. I am thinking a separate power supply chassis for a mono block.
Please comment,
Chris
PS. Or should I go for the special order non standard transformer and go unregulated?
Folks,
I am aiming for the followings, please correct/steer me away from protential problems and wrong assumptions for a newbie.
Target to go for
a/ Maximum heat dissipation 180W-200W per channel ie 2 X 11" bulk buy heatsinks.
b/ 6 devices per heatsink, so appox. 30W per device
Can I use one
625VA 24-0-24 transformer with
Bridge rectifier--->C-L-C--->
and use LM388K(on big heatsink) to regulate and provide 15V to 20V per rail for the amp board. I am thinking a separate power supply chassis for a mono block.
Please comment,
Chris
PS. Or should I go for the special order non standard transformer and go unregulated?
Wuffwaff
I have been saying that for quite sometime now it seems that nobody's listening. It's not a question of the 1.4 not working anymore, it's a question of how much voltage you have to throw away to get clean DC with the kind of currents that are circulating here.
By the way, the corollary to the 1.7 volts diode voltage drop is that these diodes are dissipating 5W each (1/2 duty cycle I think).
I have been saying that for quite sometime now it seems that nobody's listening. It's not a question of the 1.4 not working anymore, it's a question of how much voltage you have to throw away to get clean DC with the kind of currents that are circulating here.
By the way, the corollary to the 1.7 volts diode voltage drop is that these diodes are dissipating 5W each (1/2 duty cycle I think).
chris ma,
in no particular order,
1) Generally speaking, most active regulation hurts the sound for one reason or another.
2) 30W per output device is on the high side for passive cooling.
3) Without heavy regulation, that transformer will produce way too much voltage. I suggest you go for 2x18V and at least 300VA per channel.
4) The Pi filter is generally worth the extra expense.
in no particular order,
1) Generally speaking, most active regulation hurts the sound for one reason or another.
2) 30W per output device is on the high side for passive cooling.
3) Without heavy regulation, that transformer will produce way too much voltage. I suggest you go for 2x18V and at least 300VA per channel.
4) The Pi filter is generally worth the extra expense.
Thanks for the info guys,
I have spend the whole evening editing/print the entire X thread of 1490 posts and removed all noise and unrelated subjects and signatures etc, still has 208 pages of size 10 font A4 paper word doc (1.3M in size). I am reading it up to page 10 only. I am sure I have to read this book over and over in order to get a complete picture in my head. Especially for me new to Pass amps, well diy period.
Chris
I have spend the whole evening editing/print the entire X thread of 1490 posts and removed all noise and unrelated subjects and signatures etc, still has 208 pages of size 10 font A4 paper word doc (1.3M in size). I am reading it up to page 10 only. I am sure I have to read this book over and over in order to get a complete picture in my head. Especially for me new to Pass amps, well diy period.
Chris
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