Babelfish XA252 / Babelfish XA252 SIT / Babelfish XA252 SET

I’ve been to Palomar, and it was amazing. It was the rockstar of observatories in the Seventies and remained the best until the big multi-mirror arrays were in place. Then there was the Hubble Space Telescope.
If the XA252 (either version) has similar rockstar quality, then it will be well worth the wait.
Yup, my intention is, this will be my last build before retirement....sort of a lie, with as many different versions here to play with. That, and already unfinished amps, Sissy boards being altered back to original idea of M25. Then there are boxes of parts for a few others, awaiting cases and power supplies

Previously, I thought this "last amp" would be BBA3, which I have a box for with all the hard parts. XA 252 will only require one Deluxe 5U case instead of two.....back to second AlephJ.

Russellc
 
  • Like
Reactions: Mikerodrig27
I know its a while till I will build my version(s), but I think Russellc is onto something and the reason is the simple two device push-pull output stage. It doesn't matter if its Zen, PASS or anyone else designing the OS, the point is only two Power-FET's per chn (SE vers). Components also do mater, but that is noise related and time domain related and not so much crossover distortion related which is, or should be I should say, superior on amplifiers like this.
The multi OS-FET's used in PASS other amps is not why it possibly sound better or different, that is the frontstage (to a large degree). No matter how one are looking at this, using only one pair per channel (or voltage polarity for the balanced version) will always win, as long as the FET's themselves and the PSU have comparable power delivery while everything else remains fairly similar.

I guess there is room for frontend versions while maintaining the OS if someone like to tinker with that. Like the PASS DIY Front End 2022 or make a fully SuSy version which could be fun and possibly contain hidden gems.. who knows.​
 
Zen Mod: How much of the power supply ripple do you get on the output when the XA252 is configured for SIT or SET? The problem will be due to ripple on the V+ rail modulating the SIT drain voltage relative to ground. My SIT-3X amplifier uses a capacitance multiplier on the V+ rail to solve the problem.
 
I didn't bother to measure, simply - my T-Bed deliberately being on bad side of proper PSU and wiring ....... and I didn't heard/observe any performance degradation neither with SET nor SIT, vs. full MOS iteration

all that listening on efficient and also sensitive speakers

so, I don't care
 
I know it's simple to measure

though, my own XA252 not anymore on T-Bed; what was there, sent to my Bubba Bob and now singing in his Hacienda

preparing slowly to assemble mine as Flying Furnace (powder-coated in meantime) ; most likely Full MOS ...... as also intended to serve as specimen, I know that majority of FiFi aficionados around - will pee solvent in greatest volume, hearing that one
 
of course will do

I like bragging and showing offffffff

anything, just to confirm

ZM-Genius.jpg
 
  • Thank You
Reactions: Mikerodrig27