| dw8083 |
I bought 2 Antek 22v+22v 400VA trafo's on Ebay. Can I get away with just using one for a stereo Aleph30 or do I need both? Will 400va limit the amps performance?
I guess I'm asking, how much transformer is needed here?
Thank you,
-David |
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| MikeW |
| You can use it. It may have a little more mechanical hum and get a little warmer than using two. :smash: |
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| mpopovics |
I would recommend to use both.
And also recommend Nelson's article on Power supplies |
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| dw8083 |
Thanks for the guidance and suggestions. I'll use both of them.
-David |
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| Nelson Pass |
I would, if only for the ability to avoid ground loops by having
separate grounds for the two channels. |
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| MikeW |
| quote: | Originally posted by Nelson Pass
I would, if only for the ability to avoid ground loops by having
separate grounds for the two channels. |
Do you use two in your amps or one with separate secondaries (4 sets for a 2 channel) ?
:eek: |
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| motzu' |
The thread just hooked my attention.
I currently own the same type of transformer 2x22V 400VA but I never thought to try use them in an Aleph 30/Aleph 3, because I knew that voltage was supposed to be 25V DC .That if I read correctly the manual :xeye:
Anyone so kind to advise ?
From my point of view 22x1.41=~31 V
Too much for Aleph3 but slightly less for Aleph 5
Am I so lucky to find some use for those babies ?
Thank you |
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| choky |
close enough for both
go to duncan's and download PSU designer,try with diff approaches- C bank,CLC , CRC and you'll see that you can build both with these donuts.
btw 1,41 is not valid for A class:clown: |
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| tja |
| quote: | Originally posted by choky
close enough for both
go to duncan's and download PSU designer,try with diff approaches- C bank,CLC , CRC and you'll see that you can build both with these donuts.
btw 1,41 is not valid for A class:clown: |
I'm looking to build a PS for an Aleph 30 and playing around with duncan's PSU Designer II too. I could just use an 18V transformer and some caps, but if I get a 22V one and use CRC, ripple would be substantially less. Also I'm struggling with the question what value to use for the load. Anybody got a hint?
Take
[EDIT]Punctuation[/EDIT] |
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| choky |
first hint-you can unwound and also add some (additional ;) ) wounds to donut-very easilly;
second hint-for current consumtion just read service manual for exact aleph and you'll know ;
R is still equall to U/I
:clown: |
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| tja |
From the Aleph 30 manual:
"The amplifier draws about 200 watts from the wall at all times"
so 100W/ch with rail-to-rail 50V means bias is 2A, so load for one secondary is 25V/2A is 12,5 Ohm.
Correct?
Take |
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| choky |
| quote: | Originally posted by tja
From the Aleph 30 manual:
"The amplifier draws about 200 watts from the wall at all times"
so 100W/ch with rail-to-rail 50V means bias is 2A, so load for one secondary is 25V/2A is 12,5 Ohm.
Correct?
Take |
yup
read and re-read help in PSU designer;
it helps a lot |
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| Mark A. Gulbrandsen |
| quote: | | first hint-you can unwound and also add some (additional ) wounds to donut-very easilly; |
Choky, Thats not always as easy as it soulds. Many Toroids with dual secondaries have the secondaries wound one on top of the other in a bifilar manner. On those you'd have to unwind at least the one secondary to get at the other to add or take away turns.
On the Aleph I would go for both trannies. Thgose Anatek trannies are actually pretty darn good for the $$!! I've had absolutely no mechanical hum from the two pairs I've used building KSA-50's. I would reccomend them to anyone to use unless they were after the best..... Then Plitron ......
Mark |
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| Tweeker |
| I dont think a 400VA 22 VAC toroid will be a problem either, if the rails are higher than you like, just add a little more R into a CRC filter. |
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| motzu' |
Seems that i'm too idiot or too uneducated to play with the program. :confused:
@choky - could you be so kind to post a .psu file for this particular problem ? I can learn easier if I see the solution
From 22 VAC to not exceed 25 VDC .... I was unable to find out how to do it , and worse, still I'm too newbie to know how to interprete those graphs :mad:
This is it....
2'nd stupid question .Why is not valid ~1.41 for class A . Because of the high constant current needed by the amp ? The cap's are not 'charged' enough ?
BR |
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| tja |
Here's my model for a CRC PSU for the Aleph 30 with a 22V transformer.
Take |
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| choky |
| quote: | Originally posted by Mark A. Gulbrandsen
Choky, Thats not always as easy as it soulds. Many Toroids with dual secondaries have the secondaries wound one on top of the other in a bifilar manner. On those you'd have to unwind at least the one secondary to get at the other to add or take away turns.
......
Mark |
agree,my man; but-that is not always case (anyway I can tnk ya in name of original poster for additional info ;) ) ;
in case of adding several turns-it's not matter in which manner are wounded secondaries -you just add few turns and connect it in phase with adequate original windings
but-in casewhen two secondaries are wounded in bifillar manner and you need to unwound some turns.........PITA of work...... |
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| choky |
| quote: | Originally posted by tja
Here's my model for a CRC PSU for the Aleph 30 with a 22V transformer.
Take |
it's better to use current sink (2A) as load- GUI and interpret are closer to human mind :D
in any case-thumb up for sim |
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| tja |
| quote: | Originally posted by choky
it's better to use current sink (2A) as load- GUI and interpret are closer to human mind :D
in any case-thumb up for sim |
Thanks, will try that next.
Take |
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| dw8083 |
Here's the simulation I was working with for my A30. What's the best way to determine the resistance of the capacitors for the simulation?
-David |
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| choky |
| quote: | Originally posted by dw8083
What's the best way to determine the resistance of the capacitors for the simulation?
-David |
it's in fact educated guess-sollely depends on your exact caps.
for starters-you can load sample designs from PSU installation folder (program files-duncan....-PSU... by default) and just scale to your values of capacitance.
in fact -I think that this is covered in help |
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| tja |
| quote: | Originally posted by dw8083
Here's the simulation I was working with for my A30. What's the best way to determine the resistance of the capacitors for the simulation?
-David |
I used the datasheets for BCcomponents 051 series snap in caps, at the bottom of page 4 there's the 40V table which includes ESR in mOhm at 100Hz.
BC components 051 series datasheet
Take |
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| choky |
| quote: | Originally posted by tja
I used the datasheets for BCcomponents 051 series snap in caps, at the bottom of page 4 there's the 40V table which includes ESR in mOhm at 100Hz.
BC components 051 series datasheet
Take |
good 'nuff
;) |
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| dw8083 |
I have Nippon Chemi-Con 22000mf 35v caps from the recent group buy. I looked up the datasheet on the manufacter's website and they have a column for the resistance data but it is not listed. :rolleyes:
Just wondering if there was a way to measure it, or there are "typical" values for purposes of the simulation?
Thanks,
-David |
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| dw8083 |
Ok looking at the Bc components link above.... A very similar cap has a resistance of 28mOhms. If 2 caps are in parallel is the resistance halved to 14mOhms?
Thank you,
-David |
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| jacco vermeulen |
| quote: | Originally posted by dw8083
Just wondering if there was a way to measure it |
Bob Parker's ESR meter. |
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| choky |
esr meters usually works on 10 to 100KHz
nono........ |
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| jacco vermeulen |
| quote: | Originally posted by choky
esr meters usually works on 10 to 100KHz |
True, i should read the 100Hz line before posting. Bob's is 100KHz i believe.
ScuseMe. |
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| AR2 |
I just finished my Aleph 30 with exact same transformers 22V 400VA made by Piltron. It works quite fine as is. Voltage is little bit below 31V with one channell, and 29V with two channels on one tansformer. I will be using two transformers, but just for testing purpose I first tested it with one trnnie only. So far works great and transformer doesn' worm up at all.
Sound is awsome!
I love these amps. My advice - build as with what you have and than see and measure. |
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| jh6you |
Interesting . . .
I am late. Anyhow, I understand that Aleph 30 has bias current of 1.6A per channel, i.e. 3.2A for both channels. And, the peak voltages from the secondary side (ac 22v) of the transformer are +/-31V, i.e. peak to peak voltage of 62V. Therefore, the VA is calculated 3.2x62=198VA to cover both channels. I think that using 400VA is enough as long as the current capacity of total psu caps is as large as possible.
Regards
jH |
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| AR2 |
| In my case 6 x 22,000 uF per channel, or 264,000 uF for both channnels. |
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| jh6you |
12 x 22,000uF, wow ! ! !
I think them enough to cover both the ripple voltage and the whole current boosted by the active Aleph current source. Why don't you save another transformer for one more A30?
The original A30 seems to use one transformer and total 12 x 10,000uF. I don't think that its transformer size would be bigger than 400VA. No? Then, I would think that Passlab is wasting their profit . . . :D
Regards
jH |
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| Andypairo |
| quote: | Originally posted by jh6you
Interesting . . .
I am late. Anyhow, I understand that Aleph 30 has bias current of 1.6A per channel, i.e. 3.2A for both channels. And, the peak voltages from the secondary side (ac 22v) of the transformer are +/-31V, i.e. peak to peak voltage of 62V. Therefore, the VA is calculated 3.2x62=198VA to cover both channels. I think that using 400VA is enough as long as the current capacity of total psu caps is as large as possible.
Regards
jH |
Please remember that a large capacitance like the one needed will request huge current peaks that might saturate the core of the trafo it is not oversized enough, inducing mechanical vibrations and heat losses. I used a 500VA and I would suggest at least this as a "minimum" size for a stereo amplifier.
Andrea |
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| jh6you |
| quote: | Originally posted by Andypairo
. . . a large capacitance like the one needed will request huge current peaks that might saturate the core of the trafo it is not oversized enough . . .
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Well . . . the charge stored in each capacitor and the voltage between its terminals have a fixed ratio. The group of caps on + side and the other group of caps on - side would well co-operate, looking each other. Therefore, I would not worry about the core saturation with 400VA size.
Regards
jH |
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