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Aleph J for Universal Mounting Spec
Aleph J for Universal Mounting Spec
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Old 9th June 2018, 03:36 PM   #741
Zen Mod is offline Zen Mod  Serbia
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Aleph J for Universal Mounting Spec
use pair of IRFP150 , crank them to your liking

that's practically pair of IRFP240 in one case

so , no matching needed

for more info , look in (newer) Babelfish J thread

aha , yes - halve value of all 3W resistors , for that ........ 0R27 is OK
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Old 9th June 2018, 04:11 PM   #742
mattattnet is offline mattattnet  United States
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Thanks, ZM

I will look at the thread, this sounds like a great option.
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Old 9th June 2018, 08:19 PM   #743
chede is offline chede  Germany
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Aleph J for Universal Mounting Spec
I can only second what Zen Mod said.

That case combined with the lower voltage should give you the option to run much higher bias current, which is a good recipe for best sound ...

In a case comparable to your 4U/400 I have run a single pair of IRFP140 at +/- 19V and 2.2 Amp bias current. Source resistors are 0.22 Ohms.

Best regards, Claas
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Old 10th June 2018, 01:43 AM   #744
mattattnet is offline mattattnet  United States
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Thank you Claas,

I take it the .47R output resistors in parallel stay the same and dont change even with the source resistor change?

Regards,
Matt
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Old 10th June 2018, 08:24 AM   #745
Zen Mod is offline Zen Mod  Serbia
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Aleph J for Universal Mounting Spec
nope

as I said - you need to change values of all

point me to your exact schematic , and I'll write them by nomenclature
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Old 10th June 2018, 06:15 PM   #746
mattattnet is offline mattattnet  United States
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Hi ZM,

Sorry for my stupidity, when reading your Babelfish J thread, I see likely two .27R 3w resistors as output resistors if a single vertical pair of IRF120 with .27R source resistors are used.

Here is the schematic I will be following, it is the one from the most recent DIYstore Aleph J boards.
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Old 10th June 2018, 06:23 PM   #747
Zen Mod is offline Zen Mod  Serbia
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Aleph J for Universal Mounting Spec
whatever you do , R16,7,18,19,20,21,22,23 ...... are all of same value

of course that last group (sense group on output ) can be made of different number of resistors with different value (say , to have just 2pcs , not zillion ) , but group value must stay the same

practically - as many source resistors you have in output (counting up and down) , same number is in sense group
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Old 10th June 2018, 06:35 PM   #748
chede is offline chede  Germany
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Aleph J for Universal Mounting Spec
Yes,
in my single output pair Aleph (like Aleph Mini), I have 0R22 for each source resistor and 0R11 as sense group total

Best regards, Claas
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Old 10th June 2018, 07:47 PM   #749
mattattnet is offline mattattnet  United States
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thank you ZM, and Claas, my pea sized brain seems to be understanding now.

Regards,
Matt
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Old 3rd September 2018, 09:32 AM   #750
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Quote:
Originally Posted by mattattnet View Post
I have a 4U 400mm Dissipante chassis with stout dual mono +18v/-18v rails, and want to try it with a low voltage Aleph J build.

I have very efficient speakers and am not worried about maximum power output, but rather, how to get potentially the best sound out of the lower rail voltage.

Is it best to use all 4 output mosfets, or drop to one pair of outputs, ala Mini Aleph-J?

Thanks,
Matt
Can you have that 4U 400mm Dissipate chassis with UMS heatsinks? I like the 400mm depth and 40mm heatsinks, but I don't think you can get 2 X 200mm heatsinks (per each side) with "UMS" pre-drilled holes..??
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