Easy to see why dual secondaries are preferred then. So how would that effect the amplifier and/or output? Just more chance of 60hz hum, or 120hz / 180hz hum?
It should have a positive effect on the S/N ratio, in some cases more then others as different amps have different PSRR and ripple rejection. Next to the already mentioned slight drop in rail voltages there is an other matter to observe, in case the secondaries do differ, the positive and negative rail voltages will be slightly out of balance. The DC servo or conventional offset adjustment is usually capable of correcting the consequences of this. Enough for now, lets not make this side step to complicated.
Nice info. So seems if someone has a good center tapped existing suitable transformer, no need to source a dual secondary one instead.
280VA really isn't much for a stereoset, even at 50VDC rails. For an 8ohm load maby, but into 4ohm I'll guess the amp will clip due to the transformer giving up before the outputs itself.
Apologies if this has been asked before. I looked through the thread and couldn't find a definitive answer...
Are 2sc3503E and KSA1381 ESTU able to be matched up as a complimentary pair?
I've found plenty on KSC3503/KSA1381 ESTU and 2sc3503E/2sa1381E being suggested, but nothing on mixing 2sc/KSA or KSC/2sa. The Fairchild datasheet sorta implies they are one and the same. I have no clue what the difference is, if any.
Thank you in advance.
Are 2sc3503E and KSA1381 ESTU able to be matched up as a complimentary pair?
I've found plenty on KSC3503/KSA1381 ESTU and 2sc3503E/2sa1381E being suggested, but nothing on mixing 2sc/KSA or KSC/2sa. The Fairchild datasheet sorta implies they are one and the same. I have no clue what the difference is, if any.
Thank you in advance.
@birdbox your not gonna find modern KSC3503 in E-grade. Guess they had to much trouble getting the HFE right and desided to downgrade to D only.
The KSC3503D-grade will typically do around 80-85Hfe where the KSA1381E is around 120Hfe. I think some here have built the amp without problems mixing the D and E-parts.
Aske if anyone here if anyone have the 2SC3503E, you'll might get a PM🙂
The KSC3503D-grade will typically do around 80-85Hfe where the KSA1381E is around 120Hfe. I think some here have built the amp without problems mixing the D and E-parts.
Aske if anyone here if anyone have the 2SC3503E, you'll might get a PM🙂
I very much appreciate the input. My question still stands....
Anyone able to answer? Is there a difference between KSA and 2sa and KSC and 2sc? I feel like there's probably a difference, but the datasheet doesn't clarify any difference, so it leaves me wondering if there is any difference at all.
Anyone able to answer? Is there a difference between KSA and 2sa and KSC and 2sc? I feel like there's probably a difference, but the datasheet doesn't clarify any difference, so it leaves me wondering if there is any difference at all.
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I believe birdbox was talking about mixing the sanyo(?) made 2sc3503 NPN and the onsemi ksa1381 PNP parts. digikey, as at writing, listing ~55k 2sc3503e available from their marketplace (grey market supplier? edit - no, looks like Rochester is legit)
Shouldn't be a problem mixing 2SC3503 and KSA1381 I would've thought? Maybe wait for one of the build team to comment.
Shouldn't be a problem mixing 2SC3503 and KSA1381 I would've thought? Maybe wait for one of the build team to comment.
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Mouser has "Onsemi" KSA1381 ESTU in stock and Rochester has "Onsemi" 2sc3503E in stock. Can these be used as complimentary pairs if properly matched? One would assume they are different based on part numbers, but according to datasheet, KSA=2SA and KSC=2SC, which is counterintuitive.
This is the fundamental nature of my question.
This is the fundamental nature of my question.
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Reading around it looks like they will not play nice together, one is smaller bodied exposed back and the other a thicker fully encapsulated. Would mean they wouldn't thermally track well and the probably differ in performance.
Check swap meet, some forum members may still have the KSC3503E's. Or if you cannot wait, the KSC3503D and the KSA1381E work fine. I have run my amp like this for months.
Check swap meet, some forum members may still have the KSC3503E's. Or if you cannot wait, the KSC3503D and the KSA1381E work fine. I have run my amp like this for months.
Birdbox, the “onsemi” 2sc3503e are actually Sanyo devices, Fireanimal has Sanyo 2sa1381e, you can contact him, I am also interested in a few.
He actually mentioned in one of his posts the challenge in matching 2sc3503e with ksa1381e.
He actually mentioned in one of his posts the challenge in matching 2sc3503e with ksa1381e.
I am trying to match Q105 and Q106 using KSC3503 and KSA1381
The closest pairs of the 20 of each I bought are:
Everything else I have is very closely matched; it's just Q105 and Q106 that are kind of a bugbear.
I just wanted to get an opinion here.
Should I invest in more KSC3503 and see if I can get closer?
Look at other options for this part, like the TTC004BQ and TTA004BQ.
Or just use these combo's?
The closest pairs of the 20 of each I bought are:
| Vbe | Hfe | ||
| Pair 1 | KSC3503 | 693 | 119 |
| KSA1381 | 792 | 86 | |
| Pair 2 | KSC3503 | 694 | 119 |
| KSA1381 | 793 | 87 |
Everything else I have is very closely matched; it's just Q105 and Q106 that are kind of a bugbear.
I just wanted to get an opinion here.
Should I invest in more KSC3503 and see if I can get closer?
Look at other options for this part, like the TTC004BQ and TTA004BQ.
Or just use these combo's?