Babelfish XA252 / Babelfish XA252 SIT / Babelfish XA252 SET

After a short time out, finally back at getting this built. Right now cooking in slowly but surely. Pretty much the same for both channels:
Iq= 1.4A (will go high depending on heatsink temp)
Voffset= <±0.2mV (what is not to like)
Heatsink Temp = ~52°C
BD139/BD140 Temp > 57°c (and this after changing out the original heatsinks with two bigger ones.)
Still getting a tiny bit of Iq upward creep.

MJ_252_Cookin.jpg

Will make some more measurements later and then try it out on my test speakers.
Thanks to ZM for all he does around here. We need to find a way to reward him!
 
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Nice looking build!

It appears you have the dreaded bowing backplate. Some chassis do that, some don’t. :magnify: If it’s not just a camera angle anomaly, I’d suggest placing some washers in there between the bracket and the back plate to relieve the pressure and square it up.
 
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^ That's the mosfet (base) version, right? How much power does it put out? Similar to the NP XA25?

I don't know if I've posted the 252SIT... after some initial trepidation and after the upgrade to the 8V diodes...

I've got it hooked up to a CJ ET3SE... and 90db Audio Notes. AN-K/LX

The bass is really tight and deep.
The treble is extended.. a lot more than the Sissy and the Alephs. I think it actually betters the F4.
The midrange is there.... clear as a bell.

Most important is the "clarity". I can really hear the separate instruments and voices in the soundfield.
And the sound is so "clear" that there is no feeling of "loudness". I think it's not loud enough only to realize it is really playing loud that I can't hear the phone (bad) or my wife ( good perhaps? ).

I think in many ways the Macho252SIT is most like an F4, but with much more drive. A lot more dynamic. Which means the sound of the preamp is what you are listening to, the amp sort of gets out of the way.

I'm also curious about the sound of the mosfet version (and other versions).

If my speakers were 95+ dB efficient, I think I'd live with the SissySIT and get off the caboose.
With 90 dB speakers, the MachoSIT plays extremely well. Almost good enough to get off the caboose and find another hobby.

I even tried the SissySIT into the Maggies, which surprised me at how well they work, At some point I will try the MachoSIT into them.

Until then, I keep thinking that I need the quad Tokin SIT amps to reach audio Nirvana.

Will bridging the Macho 252 SIT affect it's harmonic profile? Will it bring up the 3rd order distortion?

How does the mosfet and SET versions fair with the SIT version?
 
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Will bridging the Macho 252 SIT affect it's harmonic profile? Will it bring up the 3rd order distortion?

killing evens is regular result when bridging existing amp(s)

one of goals for BigBadaBoom is - to retain dominant 2nd, despite bridged architecture

How does the mosfet and SET versions fair with the SIT version?

same Drek, differences explained on start of thread

besides slightly different max power, difference in sound is just how wide you see Jerry's smiled, back in the corner of concert stage


 
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Bravo! In my book, Figaro Rules!


Yes, I know we've discussed this via PM before... but somewhere it ought to appear in a public forum, as other people are building the other versions. Figuring out the main differences, in how they sound, is an interesting endeavor...

BTW, thanks for your work and here's hoping for the Biggus Dickus Badda Bingum amp.
 
how it sounds, after few days now?

It's been only a few days, but... Bloody hell, this amp is good! Very transparent - I can clearly hear differences between various albums - some were produced a bit dry, other softer, etc. Last time I noticed this kind of differences was when I listened to my F4 clones. Other amps, like M2, usually conceal some details by applying their own character. Bass is great, strong, deep, with a lot of details - one of the best I have ever had pleasure to listen to. Midrange is very clear, maybe a bit withdrawn, but this is probably due to my speakers having a little too much treble. Soundstage is vast, really 3D, behind the speakers. Some amps present music close to the listener, "in your face", this one is different, a bit more distant, not obtrusive.
I am really glad that I decided to build this amp. Thank you Zen Mod! :worship:
 
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Interesting.... very similar to my experience with the 252SIT. Yes, the midrange sounds sort of "withdrawn" as you say, but this could be because the treble is more forward ( my speakers don't have too much treble ) and the bass becomes so much more extended...

The soundstage is indeed wide and deep.

Oddly, the "head in a vice" quality has gotten worse with this amp. I'm at the point where I need to figure out how to toe the speakers again.

What kind of preamp are you running?
What's the efficiency of you speakers?

My preamp has a 20vpp output so it drives the F4 (clone) to a similar power level as the 252SIT. I'd say that the F4 comes closest so far.
 
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Great comments about great amps

I have listened to the XA252 Big Puck for about 8 mos
Preamp is the Iron Turtle (6dB gain) and speakers are 15" Tannoys

For me the SissySIT 42 is still my go to amp but the 252 is a close second.

Re XA252 I think the posted assessments are accurate. I myself find the presentation is balanced over the whole audio spectrum.
I really like the depth of the audio picture presented. The amp is ultimately listenable and will always be in my system with the Sissy and a Singing Bush. For historic purpose I keep a M2 and a Nelson built F3. I have built F4s, F6s. a Schaded M2. a Toshiba M2

Aleksandar's latest projects are outstanding. I hear details. musical nuances I haven't heard with previous generation amps.

Albums I listen to for "test" purposes: Norah Jones, Nina Simone, Cowboy Junkies, Clapton Unplugged, Van Morrison Moondance, Let It Bleed and few live Stones lps, White Album, Dvoryak 9, Dark Side of the Moon, Willie Nelson. Need to pull out a Colloseum lp that ZM mentioned.

I doubt we can go wrong with any of these amps :cool:
 
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Try the Brothers In Arms 45RPM MoFi LP.

Clapton Unplugged is outstanding as well. Eagles Hell Freezes Over... Any of the Chesky classics... Lt. Kije is outstanding. The MoFi version of Girl From Ipanema. Waylon and Willie -Momma don't let your boys grow up to be cowboys...

So, you like the sound of the SIT. I completely understand. the XA252SIT outdoes the SissySit 42. With the same preamp, phono, speakers, source material. I got an Iron Pro balanced on the way.... perhaps that will be a better match, gain wise, than the high gain CJ.

All I can think is that the 252 has twice the power of the Sissy. Hence, I call it Macho. The macho adds what the Sissy misses... it's like a triode sound with the lightness and bass of a pentode.

As you, I got quite a few amps, but when the Sissy 42 showed up, I stopped listening to everything else. Now that the Macho 252SIT seems to be safe from self immolation, it has been full time in the rack. I'm still a bit reticent on cranking it UP, slowly getting up there. But it sounds really, REALLY good.

So, you think I should not bother with the base Big Puck (what I call the 'base' mosfet )?

Yep, Alek is good. We should really buy him some good beers. Have a Smoky Amp get together during Burning Amp 24. I sure would love to meet him. Introduce him to some Lagunitas Imperial IPA. At 9%, after a few pints, we'll all be singing Croatian songs, together.

My long term goal is a SIT that can drive the 83db/watt Maggie 1.7s. I've hooked them up to the Sissy 42 and they sound great but not loud enough. If I could get a 100 wpc SIT amp with a 2nd order, think Macho 252 SIT, negative harmonic distortion signature, I could retire from the amp chase....

hmm... can I sell you a Bridge in NYC? ;-D
 
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@tonyEE
Great lp recommendations - I have most so I will give a listen during the next few days
Because I have the Sissy42 and the 252 Big Puck I decided not to do the 252SIT - the big Tannoys don't really need the power at least in my situation.
The Iron Turtle is a fantastic preamp.
Looking forward to BAF24

Aleksandar
Colosseum is just plain great to listen to 😊 For me time to enjoy the music
 
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