ovation sx amplifier

[andynewbe]

help ! help ! help ! 😱😱hi ime about to build myself a sx amplifier, got all the bits ect, but for love nor money can i get some ksc3503e transistors ? if any body out there has any spare i will pay reasonable price or can advise me what i can do ?

 

[Keruskerfuerst]

I found these transistors at digikey.com
Here: https://www.digikey.de/products/de?keywords=transistor&keywords=ksc3503e&pkeyword=transistor&v=

 

[globalplayer]

Verfügbare Menge 0

 

[globalplayer]

Free shipping 10pcs/lot C3503 TRANS NPN 300V 0.1A TO 126 Transistors (BJT) Single 2SC3503ESTU-in Integrated Circuits from Electronic Components & Supplies on Aliexpress.com | Alibaba Group

 

[bullittstang]

Found these at Mouser (3,800 in stock)- KSC3503DS ON Semiconductor / Fairchild | Mouser

EDIT - Also at Digikey too (3,999 in stock)

 

[globalplayer]

^
This is the D grade.
OP wants/needs the E grade.

h FE Classification
C 40 ~ 80
D 60 ~ 120
E 100 ~ 200
F 160 ~ 320

 

[jacques antoine]

I bought last year 10 pairs Fairchilds KSA1381E / KSC3503E from DIYaudio user Joshvi who has a big supply.
They work fine. Maybe he has some left?
Cheers,
Jacques

 

[andynewbe]

thanks for all your inputs , got hold of joshvi today and waiting for a response ,ta andy

 

[AndrewT]

I also bought from Member Joshvi.

Unfortunately from the three sets of D grade and two sets of E grade I have almost none that have similar hFE across P:N

 

[thimios]

Yes, Johsvi sell both E grade but don't expect to find matched pairs.

 

[andynewbe]

ovation sx

hi ive ordered a few sets from joshvi but ive also got 20 x ksa1381estu and 20 x ksc3503dstu from mouser ! fingers crossed should find something close enough😕

 

[thimios]

SX will be happy with no matched pair VAS

 

[akimmet]

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.

 

[andynewbe]

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

 

[Bill_P]

Board is marked incorrectly. R20 is 2.2K. The version 2.10 document for the SX amp shows R4 is not to be placed on the board. See the schematic page 14. Note that link J2 shorts across R4 anyway.

 

[AndrewT]

I was actually able to get closer hFE matches in-between D and E pairs, rather than from the few KSA1381E I have. <snip>

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.

 

[Wolletje]

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

 

[bambadoo]

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

 

[Bonsai]

I incorporated your feedback from your build into the latest document bambadoo - should be up to date.

Wolletje, V1.0 boards are quite old - there were a few component value changes IIRC after that. Where did you get you boards from?

Here is the link to the sx-Amp article Ovation sx-Amplifier: A High Performance 15 W Class A Current Feedback Amplifier

If you have questions, just email me.

 

[Wolletje]

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

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