Hi Tony,
I was waiting til they showed stock of kta1381,ktc3503, but you ordered anyways. Hope all works out well
BTW, not sure if you noticed that Digikey has EVO brand version of A1837, C4793. I bought some to try out.
Rick
I was waiting til they showed stock of kta1381,ktc3503, but you ordered anyways. Hope all works out well
BTW, not sure if you noticed that Digikey has EVO brand version of A1837, C4793. I bought some to try out.
Rick
Because the shipment was fully booked before arrived. Now they backordered.
Friends, I finally got around to replacing the internal cabling after a year. I replaced the cheap chinese cables with SUPRA branded ones.
1, for power connection SUPRA RONDO 4x2,5mm
2, for speaker connection SUPRA RONDO 2x2,5mm
3, for signal connection SUPRA DUAL
Old cabling
Upgrade cabling
1, for power connection SUPRA RONDO 4x2,5mm
2, for speaker connection SUPRA RONDO 2x2,5mm
3, for signal connection SUPRA DUAL
Old cabling
Upgrade cabling
Some thicker copper can help to make the measurement figures look better beyond 0.00xxx percent 😎 and it would be very very difficult to hear a difference using SA2014 circuit ...
BTW: I am currently listening music using my 4 channel SA2014 built 2014 with more than 21000 operating hours. WOW
BTW: I am currently listening music using my 4 channel SA2014 built 2014 with more than 21000 operating hours. WOW
Onsemi discontinued the el-cheapo ksa940/ksc2073 that i use along with Toshiba 2sa1943n/2sc5200n in the stk clone
EVVO 🙂 sells both the ksa940/ksc2073 & A1837/C4793 for about the same price. MJE1503x are more expensive.
There is a cost saving using the isolated package, not needing the insulator, shoulder washer, but Pd is not as good as the exposed metal.
It's nice to see the new chassis heatsink brackets in use. A few threaded inserts in the back makes it easier.
Did you have fun with the bottom screws for the front panel? I used some studs inserted into the FP first, attach to the bracket using a flat/lock washer, nut or keps nut. A small wrench to tighten.
Wiring looks neater, what gauge original and after? #16AWG should be good enough.
21000 operating hours, cheers, let's hope the KEC parts are just as reliable.
Transistors should last "forever" - only "electro migration" problem operating the parts near limits will kill them. Maybe the Voyager space probe has no lytics on board to stabilize the on board voltages (offered by nuclear batteries). This may explain the reliability of the electronics.
SA2014 may get problems after another 20000 - 50000 hours of operating when some lytics going the path to death (dry out). But thats maybe beyond my personal lifetime and it is very likely that I can never report this event to the DIY community 🤣
Have fun, Toni
P.S.: The EVVO A1837/C4793 are looking not to be a good replacement for Toshiba A1837/C4793. The Unisonic (UTC) or KEC variants are closer to the original
SA2014 may get problems after another 20000 - 50000 hours of operating when some lytics going the path to death (dry out). But thats maybe beyond my personal lifetime and it is very likely that I can never report this event to the DIY community 🤣
Have fun, Toni
P.S.: The EVVO A1837/C4793 are looking not to be a good replacement for Toshiba A1837/C4793. The Unisonic (UTC) or KEC variants are closer to the original
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Dear Roman,
what I can't clearly see if the speaker output minus is as short as possible connected to the GND input stage... the new/second picture shows a small cable ...
(effectively minimizes dc offset and THD+N; case design and input/output stage placement and new cable routing allows you to get the best out of the design)
what I can't clearly see if the speaker output minus is as short as possible connected to the GND input stage... the new/second picture shows a small cable ...
(effectively minimizes dc offset and THD+N; case design and input/output stage placement and new cable routing allows you to get the best out of the design)
Hi Toni,
I am still very curious about how your testing is going with KEC devices. Can't wait to see your results.
All my required devices have arrived except KSA1381. I got KTA1381 (only 3 pieces), since KSA1381 is EOL, it was "back order" when I ordered it, but went out of stock.
So I have following two alternatives with me, if I can use them!
O1, Can I use KSA1142 in place of KSA1381 (Q12,Q13 in sa2014_input_vas_stage), I know KSA1142 is a 180v, Ic=100mA, hfe=114, Pc=8W, ft=180Mhz and Cob=4.5-7pf with a good SOA.(also EOL)
https://www.mouser.com/datasheet/2/149/KSA1142-89939.pdf
OR
O2, Can I use KSA1156 is a 400v, Ic=500mA, hfe=145, Pc=10W.
https://www.mouser.com/datasheet/2/149/KSA1156-62023.pdf
Pardon my ignorance I am a beginner and trying to learn.
Regards,
Arshad.
Attachments
KSA1142 has a bit more limited SOA compared to KSA1381. The Cob looks similar if we compare the -10V
Maybe it is working but maybe you need to tune the negative feedback loop. No guarantee at all...
Maybe it is working but maybe you need to tune the negative feedback loop. No guarantee at all...
Tuning the feedback loop would be difficult for me, for now I'll make single channel with A1381 and later test the A1142 maybe I'll get lucky and it will work as you said. Meanwhile I'll try to source more A1381 form other suppliers.
Thanks.
Thanks.
SA2021 - NCH (New Class H) is now playing some weeks every day. My opinion: it's the successor to SA2014 (of course SA2014 has lower THD) with low idle power dissipation and more peak power. SA2014 is, was and will be the ultimate power horse in the context of maximum sound fidelity, but SA2021-NCH as a green variant of SA2014 is a wonderful replacement of all other power amplifiers in my home cinema. SA2021 pcb's for nerds are available - do you have the skills to build your own SA2021?
SA2021 tower design - absolutely noiseless. No hiss, no hum, no noise if input disconnected/shorted. All noise measurements reach the limits of my measurement device (VP7723D).
NOTE: SA2021-NCH - a team design by Dave Zan and me with many know how from the diyaudio community.
Have fun, Toni
SA2021 tower design - absolutely noiseless. No hiss, no hum, no noise if input disconnected/shorted. All noise measurements reach the limits of my measurement device (VP7723D).
NOTE: SA2021-NCH - a team design by Dave Zan and me with many know how from the diyaudio community.
Have fun, Toni
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Hi Toni,
I seem to recall that you once said your NCH design is a self oscillating amplifier, acting similar to a class H one, but without requiring multiple supply rails. So, does it resemble a class D one? Would you like to share some details? Thank you!
Best regards!
I seem to recall that you once said your NCH design is a self oscillating amplifier, acting similar to a class H one, but without requiring multiple supply rails. So, does it resemble a class D one? Would you like to share some details? Thank you!
Best regards!
60-60pcs of KTC3503/KTA1381 arrived yesterday.
Any updates regarding KTC3503/KTA1381? Are you satisfied with your testing results?
I think the parts are a good replacement for 2SC3503/2SA1381. What do you think/whats your experience?
Have fun, Toni
I think the parts are a good replacement for 2SC3503/2SA1381. What do you think/whats your experience?
Have fun, Toni
Not yet built in, but testing results are fine. Hfe is around 150, and looks easy to find pairs. KEC has some promising parts...
After some testing it looks good that all SA20xx series amplifiers can be build with available replacements from KEC and Unisonic (available at profusion.uk)
Of course BC550C/560C are hard available but can be replaced by BC327-40/337-40 without big degradation...
Happy DIY
Of course BC550C/560C are hard available but can be replaced by BC327-40/337-40 without big degradation...
Happy DIY