Experimental powersupply for Aleph4

blank527 · 3rd July 2002, 08:02 PM

Hi,
I'm currently building an Aleph 4 with many expectations.
Does it really sound so different compared to other amps?
(What a great forum!)
I have in stock 2 times 500VA 2x35Vsec transformers and want it to use it in this schematic (see picture)[IMG]D:\Documents and Settings\Prapper1\Desktop\experiment.jpg[/IMG] Is this OK?
The heatsinks that i'm planning to use has got a size of 32cmx30cm per each channel wich comes around 960 square centimeters. Mcfinnis has got 1060. So I think I come pretty close!

Thanks in advance
Remco

blank527 · 3rd July 2002, 08:46 PM

Sorry, I forgot to post my question...

Should this schematic work?
Or should i go for one 1KVA transformer!

Nelson Pass · 3rd July 2002, 08:53 PM

Assuming to get about +/- 50 volts on this supply
it should work, but the transformers will be running
close to their ratings, and will get hot.

Worst case? They fail after some time.

blank527 · 3rd July 2002, 09:02 PM

Thanks Mr Pass!
So should go for 1 peace of 1KVA!
(then I'm having trouble with space)
I'll figure something out...

Any other solutions?
I've got spare space of 6.6cm by 30cm just enough for 2X500VA.
The fahrads is hopefully enough!
Give me your opinions! I love it!
Thanks everyone!
Remco

wuffwaff · 3rd July 2002, 11:19 PM

Hi Remco,

you could always use PSUdesigner for these kind of questions

It´ll give you very good figures for all the currents/voltages in your supply.
With these caps and chokes you should get around 10-20mV ripple @ 3A.

(don´t have the link at the moment though

)

william

Edwin Dorre · 5th July 2002, 10:16 AM

Quote:

Originally posted by blank527
Thanks Mr Pass!
So should go for 1 peace of 1KVA!
(then I'm having trouble with space)
I'll figure something out...
Any other solutions?
I've got spare space of 6.6cm by 30cm just enough for 2X500VA.
The fahrads is hopefully enough!
Give me your opinions! I love it!
Thanks everyone!
Remco

You should not load a transformers for more than 60% . So 1000VA with a contigious load of about 500W is close to there limit. My 1000VA running 250W is till getting hand warm and produces a little hum... I hate to think when you contigious load of twice 250w... When you load them beyond 60% the voltage will drop dramaticly!

Mine 1000VA 40-0-40 with 88000uf with a 250W load gives about +49.2V ... I hate to think what happens when you load 2x500VA 35-0-35 with 500W ...

Edwin

blank527 · 5th July 2002, 02:10 PM

So the original Aleph 4 uses also 2X 1000VA transformers?
I thought it uses only 1 transformer according to other threads.
Can anyone post some inner pictures from the original Aleph 4?
Thank you,
Remco

AudioFreak · 5th July 2002, 03:57 PM

Quote:

Originally posted by blank527
So the original Aleph 4 uses also 2X 1000VA transformers?
I thought it uses only 1 transformer according to other threads.
Can anyone post some inner pictures from the original Aleph 4?
Thank you,
Remco

For capacitor input linear power supplies with constant average load like this, minimum transformer rating is Power draw / 0.62 so for the Aleph 4 with constant draw of 500W, minimum transformer rating is about 810VA so 1kVA is enough but in practice we always like to over do things, personally, I would use separate transformers for each channel with 1.6kVA per channel but that is just my personal taste in excessiveness.

fcel · 5th July 2002, 04:13 PM

I read that the rule of thumb for sizing transformer is 7.5 times that of amplifier output. So, for 100w/ch, you'll need at least a 750VA transformer per channel.

AudioFreak · 5th July 2002, 04:22 PM

That is very much an idealistic situation in practice you dont 'need' anywhere near 7 or even 3 times the power draw but if you have the space and the money, it certainly doesnt hurt to get a transformer spec'ed for a much higher power rating.

3rd July 2002, 11:19 PM	#5
wuffwaff diyAudio Member Join Date: Aug 2001 Location: Ingolstadt Germany	Hi Remco, you could always use PSUdesigner for these kind of questions It´ll give you very good figures for all the currents/voltages in your supply. With these caps and chokes you should get around 10-20mV ripple @ 3A. (don´t have the link at the moment though ) william __________________ een ooievaar is geen konijn want zijn oren zijn te klein!

5th July 2002, 04:13 PM	#9
fcel diyAudio Member Join Date: Sep 2001 Location: LA County	Rule of Thumb I read that the rule of thumb for sizing transformer is 7.5 times that of amplifier output. So, for 100w/ch, you'll need at least a 750VA transformer per channel.

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3rd July 2002, 08:46 PM	#2
blank527 diyAudio Member Join Date: Nov 2001 Location: Haarlem	Sorry, I forgot to post my question... Should this schematic work? Or should i go for one 1KVA transformer!

3rd July 2002, 08:53 PM	#3
Nelson Pass The one and only Join Date: Mar 2001	Assuming to get about +/- 50 volts on this supply it should work, but the transformers will be running close to their ratings, and will get hot. Worst case? They fail after some time.

3rd July 2002, 09:02 PM	#4
blank527 diyAudio Member Join Date: Nov 2001 Location: Haarlem	Thanks Mr Pass! So should go for 1 peace of 1KVA! (then I'm having trouble with space) I'll figure something out... Any other solutions? I've got spare space of 6.6cm by 30cm just enough for 2X500VA. The fahrads is hopefully enough! Give me your opinions! I love it! Thanks everyone! Remco

5th July 2002, 02:10 PM	#7
blank527 diyAudio Member Join Date: Nov 2001 Location: Haarlem	So the original Aleph 4 uses also 2X 1000VA transformers? I thought it uses only 1 transformer according to other threads. Can anyone post some inner pictures from the original Aleph 4? Thank you, Remco

5th July 2002, 04:22 PM	#10
AudioFreak Warp Engineer On Holiday Join Date: Oct 2001 Location: Queensland, Australia	That is very much an idealistic situation in practice you dont 'need' anywhere near 7 or even 3 times the power draw but if you have the space and the money, it certainly doesnt hurt to get a transformer spec'ed for a much higher power rating.