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Babelfish XA252 / Babelfish XA252 SIT / Babelfish XA252 SET
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Old 14th June 2021, 10:00 AM   #81
Zen Mod is offline Zen Mod  Serbia
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Quote:
Originally Posted by PierreQuiRoule View Post
Thank you. How could I have missed these? I guess I blinked. The SIT adds character (more 2d harmonic).

Zen Mod, please do you expect a big difference in distortion at higher frequencies between the two devices? I saw your frequency sweep but am wondering if the SIT geometry offers any advantage up there when pushed. (Probably not given they are both large devices but who knows...)

Too many attractive options here!
more from experience with SissySIT than from Freq. graphs I posted - I'm not losing my sleep about details as that
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Old 14th June 2021, 11:29 AM   #82
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to clarify that - I wrote around noon, in time of first morning coffee (damn, last evening I was tired but got some idea to try - first draw on back of napkin, then to put in LTS, then - wonder - in Eagle and work on pcb ....... so I really dunno what time was when I got to bed; did I? )

all MOS iteration, even if we can see tiny roll-off at 20K, in listening tests didn't rise a brow regarding bloody anything

so, looking just at Freq. graphs, comparing all MOS and DEF iterations, DEF is looking more linear up, but - as I said - MOS is flawless, so what one can expect from even more flawless?

I know main culprit why there is little sag at 20K in MOS version - generally, I was overcautious with cap compensations everywhere, main reason for that being that I wanted to have relatively broad range of BFR values, without need for varying feedback lag cap ( there is none in present amp, even if there is position on pcb, and it is shown on sch)

so, I got that ; looking at 10K squares, with 22R for BFR , there is sliiiight overshoot at leading edge, while with 510R as BFR - there is sliiiight softening of leasing edge

pretty much as I wanted it

in short - if you're younger than 17, maaaaaaaaaybe you'll hear difference in highs between MOS and SIT versions ..... though - hardly ...... even not taking in account fact that with 17 one is mostly interested in other things, not flybating with amps and speakers
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Old 14th June 2021, 11:53 AM   #83
PierreQuiRoule is offline PierreQuiRoule  Canada
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Thank you Zen Mod. I was not clear, sorry. The small roll off, especially above 15K, is of little concern to me, having played with speakers, placement, crossovers, etc... Agree with you there are bigger factors at play there.

I was referring to your distortion vs frequency graph. The Stereophile measurements of Papa's amp at 8.9V output show that distortion rises at higher frequencies, and I am wondering whether the THF51 in your design behaves the same, better or worse. The distortion remains very low in level considering the size of the devices. After re-reading your SissySIT (thank you for hint) this sounds like an academic question, so please feel free to disregard! Thanks for sharing.
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Old 14th June 2021, 02:54 PM   #84
AlexRivera is offline AlexRivera  United States
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Alert setup on the Swap Meet so I donít miss this kit when available!!
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Old 14th June 2021, 02:56 PM   #85
Zen Mod is offline Zen Mod  Serbia
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plenty of current ones to deal with, amassing parts and pcbs ...... my head hurts (as Homer would say)

so, this one on hold, for a moment ........ or two
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Old 14th June 2021, 07:22 PM   #86
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Default Babelfish XA252 SIT - graphs , 8R load, BFR=510R

.... everything same (rails +/-30V, Iq 1A7)
Attached Images
File Type: png Babelfish XA252 SIT 1W 8R.png (32.2 KB, 224 views)
File Type: png Babelfish XA252 SIT 5W 8R.png (32.8 KB, 223 views)
File Type: png Babelfish XA252 SIT 10W 8R.png (34.0 KB, 222 views)
File Type: png Babelfish XA252 SIT 15W 8R.png (35.2 KB, 221 views)
File Type: png Babelfish XA252 SIT 20W 8R.png (35.3 KB, 218 views)
File Type: png Babelfish XA252 SIT 25W 8R.png (36.1 KB, 35 views)
File Type: png Babelfish XA252 SIT 30W 8R.png (43.7 KB, 41 views)
File Type: png Babelfish XA252 SIT Freq. 8R.png (47.2 KB, 39 views)
File Type: png Babelfish XA252 SIT THD vs. Freq. 8R.png (49.1 KB, 24 views)
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Old 14th June 2021, 07:24 PM   #87
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Default Babelfish XA252 SIT - graphs , 4R load, BFR=510R

Load changed to 4 Ohms

post 1 of 2, more pics than allowed for one post
Attached Images
File Type: png Babelfish XA252 SIT 1W 4R.png (32.4 KB, 31 views)
File Type: png Babelfish XA252 SIT 5W 4R.png (33.2 KB, 27 views)
File Type: png Babelfish XA252 SIT 10W 4R.png (34.3 KB, 24 views)
File Type: png Babelfish XA252 SIT 15W 4R.png (35.5 KB, 22 views)
File Type: png Babelfish XA252 SIT 20W 4R.png (35.7 KB, 20 views)
File Type: png Babelfish XA252 SIT 25W 4R.png (36.3 KB, 20 views)
File Type: png Babelfish XA252 SIT 30W 4R.png (36.3 KB, 30 views)
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Old 14th June 2021, 07:26 PM   #88
Zen Mod is offline Zen Mod  Serbia
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Default Babelfish XA252 SIT - graphs , 4R load, BFR=510R

post 2 of 2
Attached Images
File Type: png Babelfish XA252 SIT 35W 4R.png (36.4 KB, 47 views)
File Type: png Babelfish XA252 SIT 40W 4R.png (44.3 KB, 44 views)
File Type: png Babelfish XA252 SIT Freq. 4R.png (47.6 KB, 39 views)
File Type: png Babelfish XA252 SIT THD vs. Freq. 4R.png (48.9 KB, 32 views)
File Type: jpg IMG_20210614_204013.jpg (149.6 KB, 95 views)
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Old 14th June 2021, 07:33 PM   #89
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Default Conclusion !

My preferences:

-Babelfish XA252 (that being All Mos):

rails between 30 and 35Vdc - depending how much power is needed, Iq everything between 1A and 2A, depending how much aluminum is on disposal, BFR-22R



-Babelfish XA252 SIT:

rails 30Vdc, Iq 2A, BFR-22R

Hasta La Vista, Baby........ I'll be back!
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Old 14th June 2021, 09:17 PM   #90
PierreQuiRoule is offline PierreQuiRoule  Canada
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You spoil us ZM. Thank you and congratulations for completing the story! No more questions from me. Will ping for pcbs or Gerbers in due time, but lazy me must complete another half-finished amp first...
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