Babelfish XA252 / Babelfish XA252 SIT / Babelfish XA252 SET

[G600]

They are usually inductive, it can be a good thing, like for PSU, but note everywhere.
Maybe it doesn't matter here, ZM will tell.

 

[Zen Mod]

mox are prettier

 

[Russellc]

Zenmod, you have PM

Russellc

 

[andynor]

PMS?

 

[Zen Mod]

damn greenhorn vikings

 

[dBel84]

I needed to replace the relay in the soft start because previous gremlins managed to weld it kaput. Now with more simple CRC, we have success at all volumes. I can finally cook it and then bring it out of the lab..dB

 

[Zen Mod]

 

[tonyEE]

I just finished building an Alephj and it sounds really nice, but I am spoiled by this XA252. It beats anything I have heard or built so far. More people need to build this one, RusselC has the right idea of building multiples, and honestly if you could only build one amp the XA252 would be it. I just really enjoy the whole building process(plus who doesnt enjoy their wife asking why you need 3 preamps, 4 DACs and 4 Amps when you never listen to music anyways)

which version?

 

[Bensen]

Another one is alive. First iteration of PCB’s assembled on a testbed. Rails are 30v, currently biased at 1,5A. Listening Enya during typing.

GND star point is created on the OPS pcb. Idea is to add 63v 22000uf Mlytic’s on the OPS pcb.

Bias behaves well during clipping.

 

[Bensen]

Did someone answered to this question? I am also interested about this information. What would be the max Idss for these jfets do use in Babelfish XA252 mosfet version?

Can I replace BD139/BD140 with Toshiba TTA004B/TTC004B? Are there also other parts that I can substitute with a Toshiba parts?

What is the difference between Babelfish XA252 mosfet and SET version besides some extra small parts?

My speakers are 8 ohm 88db.

I have 500VA transformer 4x18VAC. Can I use it to build Babelfish XA252 mosfet version? Ideal would be 2x28VAC and 600VA? What is the max rail voltage to go with this mosfet version? If I go for 500VA 2x36VAC and using cap multipler or SLB smooth like butter to drop some voltages is this then doable?

Is 4U/400 case ok for that if I use my transformer 500VA, 4x18VAC? If I go for higer voltage rails then will be 4U/500 case be also OK?

5U/400 case is really Fugly!

I am sorry for so many questions. 🙂

I just replaced the BD parts with the TTA + TTC004 combo. I did comparison with 20kHz 10Vpp on a 7R load // 100n.
Result is identical.
01 = BD's
02 = TTC+TTA

 

[dBel84]

Might need some babysitters. After 3 hours of continual play at lively volumes, heatsinks are #@$* hot, (72deg C). Sounding really luvely tho.

 

[Mikerodrig27]

What is your bias set to? The heatsinks look to be about the size of a 4U is that right?

 

[Jacruzer787]

^ They are HUGE size!

 

[dBel84]

What is your bias set to? The heatsinks look to be about the size of a 4U is that right?

Bias is 1.9 A and heatsinks are 12.5 x 9.x 3.25, they weigh about 10lbs each.

I tried some generic fans I had on hand but they are too noisy. So picked up some noctua which seem to be doing the trick.

 

[Bensen]

I’m breaking my head on what to do with the 1uf coupling caps.
Currently, I have Wima MKP10 in there. Other possibilities are 3x 0u33 NPO smt’s (using this in the dc-offset correction feedback), or I could go for a Mundorf EVO cap (place is foreseen on my pcb).

Big Mundorf’s will pick up more noise.
Soundwise, I don’t have the experience to tell what’s best. This amp deserves best!

 

[Zen Mod]

just short it, dammit

 

[Bensen]

Forgot to mention that I ment C13 +C14, coupling to output stage😉

 

[Zen Mod]

these are bypass for biguns

you'll not hear difference, even if you use caps made of preputium

 

[tonyEE]

Speaking of BA3... got another F4. One is SE, the other is Bal and SE.. has the FE. So, now I got to figure out how to set them up bridged, I believe it was a cable driving both sides of the amp, in SE mode... bridged?

I recall the conversation about this.... before the Sissy and Macho 252 came to be..

Getting another F4... so the 2nd and 3rd will be identical, balanced and SE. Will drive them bridged with a BA3

The BA3 is already sitting on top of a couple of Iron Pre Balanced preamps... will all the cables. Blocking the fireplace.

In the meantime,. the first F4 is being driven by the CJ ET3SE ( 20 Vrms output )....

Macho 252 is in the amp hospital....

 

[Bensen]

What happened with your 252 Tony?