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Aksa Lender P-mos Hybrid Aleph (ALPHA) Amplifier
Aksa Lender P-mos Hybrid Aleph (ALPHA) Amplifier
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Old 16th April 2018, 11:31 AM   #1761
xrk971 is online now xrk971  United States
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So we are talking about 15mV of ringing under 10nS rising edge square wave excitation? If square wave was 8vpp, would ringing be commensurate or still in mV range? I don’t think this sounds like an audio issue anymore if it requires a pathological example of excitation.
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Old 16th April 2018, 11:55 AM   #1762
keantoken is offline keantoken  United States
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Output is proportional to input. The simulation used a 100mVpp square wave input. There is more ringing than that because the HP filter attenuates it a bit.

You would get more ringing in proportion to the input square wave level, but it would still be hidden in the root of the wave and undetectable, hence the HP filter to make it detectable.
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Old 16th April 2018, 12:30 PM   #1763
zman01 is online now zman01  Bangladesh
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Quote:
Originally Posted by xrk971 View Post
Watchtmouse,
You are moving fast. 100uF 16v is all you need and not 1000uF 50v. That was my fault for over spec. I would use 220uF 25v if you have it. It doesn’t see anything higher than rails / 10 or 2.5v.
Hi X,

Exactly which position is being discussed here? A 100uF to 220uF cap for C103?

IIRC the bill of materials had 47uF for C103 - a change to that is being suggested?
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Old 16th April 2018, 12:45 PM   #1764
xrk971 is online now xrk971  United States
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Quote:
Originally Posted by zman01 View Post
Hi X,

Exactly which position is being discussed here? A 100uF to 220uF cap for C103?

IIRC the bill of materials had 47uF for C103 - a change to that is being suggested?
Hi Zman,
The cap I was referring to is the feedback shunt cap C111 below (220uF 25v is plenty here):
Click the image to open in full size.
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Old 16th April 2018, 12:57 PM   #1765
irribeo is offline irribeo  Netherlands
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http://www.diyaudio.com/forums/attac..._104926978-jpg

Question was about c103 as in picture, not c111.
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Old 16th April 2018, 01:27 PM   #1766
xrk971 is online now xrk971  United States
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Thanks, Irrebeo,
My mistake - C103 needs to be 1000uF and at least 35v and the large value is for the anti thump feature.

Folks:
In the future please attach schematic and specify part label when asking questions about specific parts and mods. Hugh’s schematic and JPs64’s Schematics have different labels.
Thanks
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Old 16th April 2018, 02:10 PM   #1767
watchtmouse is offline watchtmouse  Germany
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Quote:
Originally Posted by xrk971 View Post
Thanks, Irrebeo,
My mistake - C103 needs to be 1000uF and at least 35v and the large value is for the anti thump feature.

Folks:
In the future please attach schematic and specify part label when asking questions about specific parts and mods. Hugh’s schematic and JPs64’s Schematics have different labels.
Thanks
Wasted some shipping costs here, yesterday I ordered the wrong value, no big deal.

Then again the question, but with more context ;-)

1). Alpha 20 JPS64 schematic, The C103 cap, Due to the limited size on the Alpha 20 board, a 1000uF capacitor will not fit, the max diameter for the C103 cap is 10 mm and the RM is 5 mm, this gives me a max of 470 uF 50 V (10 times the original of 47 uF (C103 is named C2 in the original AKSA schematic).
Now to the question, is the 1000 uF important or will any bigger cap as 47 uF do?

Sorry for being a nucance

Happy listening

Bert
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Old 16th April 2018, 02:24 PM   #1768
AKSA is offline AKSA  Australia
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470uF is fine! This caps affects only turn on and has no influence on sonics!

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Old 16th April 2018, 02:31 PM   #1769
cl00sed is offline cl00sed  Ireland
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Default Aksa Lender P-mos Hybrid Aleph (ALPHA) Amplifier

Hugh,

Could you please provide possible list of fets for alpha 20 4ohm version
I have the irf’s for 8ohm version

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Old 16th April 2018, 02:45 PM   #1770
danny_66 is offline danny_66  Belgium
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IXTK90P20P TO264 890W 90A 12nF 200V 50S
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