ovation sx amplifier

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akimmet

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Joined 2011
I was actually able to get closer hFE matches in-between D and E pairs, rather than from the few KSA1381E I have. In my case all of the KSC3503E I had were on the low end for grade E, while the only two KSA1381E I had were on the high end. However I was able to find a few KSA1381D that had high gain.

If my notes are correct, I gave up and settled on 109 KSA1381D and 128 KSC3503E, instead of 168 & 170 KSA1381E with 132 KSC3503E.

A vast majority of my KSA1381D had a hFE of 97-98 with a few outliers. While all of my KSC3503E had a hFE of 128-132.

I was able to get excellent hFE matches mixing some Sanyo 2SA1381E and Fairchild KSC3503E, but decided against doing that. I don't have access to a curve-tracer to truly know if the Fairchild parts properly match the Sanyo parts.
 
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andynewbe

Member
Joined 2018
ime building the sx boards at the moment ,, can anyone confirm or help me ? the board come from jims audio , on the boards( r20) is marked( 220)......and (r4) is marked( 100k)........ the bom list (r20) is quoted as (2.2k) and (r4) quoted as (15) which one is up to date ? what ones should i use
 
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AndrewT

R.I.P.
Joined 2004
akimmet said:
I was actually able to get closer hFE matches in-between D and E pairs, rather than from the few KSA1381E I have. <snip>
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I found much the same and also decided not to mix Sanyo with Fairchild.

When the pre-driver draws very little current as in a triple stage output, then differences in hFE don't amount to much. The VAS works as expected.

But where the currents are high as in a two stage output, the hFE difference results in a large sinking of the VAS current, or a large injection into the VAS current sink. Either upsets the care that we try to set up the VAS stage.
 
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Wolletje

Member
Joined 2018
SX amplifier 2012 V10 version

Hi,
I got just 2x boards with sx-amplifier V1.0 Andrew C Russell 2012 and 2x power supply
Is there somewhere a Bom list and building guide or some other information about this diy circuit?
I do not how to start yet....I search but get not the right information
With regards
Frist
 

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Bonsai

Bonsai

www.hifisonix.com
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Wolletje

Member
Joined 2018
bambadoo said:
The ovation-nx thread is a bit more comprehensive in that regard.
sx-Amp and nx-Amp

However I ran into some issues building mine. Made a writeup but unfortunately it is in Norwegian. Maybe you can google translate?
Great amp BTW:
15 Watt klasse A -> Ovation-SX - Side 5
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Hi
Thanks a lot for this very usefull information! The translation is not 100% but I can understand the most of it in this translation from Google
Maybe you have more information like a BOM list, instructions or more pictures of the amplifier board and the psu? These can be very helpful for me. With regards Frits
 
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