Rails are rather high, 34V after the SLB PSU. What's the reasoning behind your comment regarding 30vdc/5ohm? I'd like to learn😀
30vdc is the minimum ZM recommends for the big pucks because of interelectrode capacitance increasing substantially under this value.
So 30vdc is the minimum you can go. With 30v rails and enough bias you will get close to 100w in 5r and double of that into 2r.
The same ZM recommended higher rails if you want to get same power but into 8r.
Since your speakers stay more in the 2-5r range it would be better to lower the rails and increase the bias.
Lowering the rails from 34v to 30v will increase the thd a bit but it’s up to you to decide which is the best compromise that you will make.
Same ZM said that an amp it’s made out of compromises and now I get him better why he said that. The good thing is that being diyers we can build and adjust to our needs.
So 30vdc is the minimum you can go. With 30v rails and enough bias you will get close to 100w in 5r and double of that into 2r.
The same ZM recommended higher rails if you want to get same power but into 8r.
Since your speakers stay more in the 2-5r range it would be better to lower the rails and increase the bias.
Lowering the rails from 34v to 30v will increase the thd a bit but it’s up to you to decide which is the best compromise that you will make.
Same ZM said that an amp it’s made out of compromises and now I get him better why he said that. The good thing is that being diyers we can build and adjust to our needs.
Thanks, that does makes sense. I don't know how to and if to lower the rails but I will consider this as a possibility to further improve.
I am in the fortunate position of having a SissySIT P on my to build list. The other option would be to bi-amp with the SIT on the coaxial and the XA252 on the midwoofer. This would mean surgery on the Thiels😱🤔. (and of course multiple Iron Pre's ,DACS etc)
Possibilities are virtually endless!
I am in the fortunate position of having a SissySIT P on my to build list. The other option would be to bi-amp with the SIT on the coaxial and the XA252 on the midwoofer. This would mean surgery on the Thiels😱🤔. (and of course multiple Iron Pre's ,DACS etc)
Possibilities are virtually endless!
if it was me I would just bias properly the xa252 and forget about the rest. With properly I mean to give me 30-50W in class A.
Now I think you are aware that if you want to get 100W into 2r and all of them in class A you will need to bias your amp close to 3A which is quite difficult from device SOA pov and dissipation pov.
First of going the route of biamping I think it`s worth checking the impedance for the group of speakers(in a speaker) you want to use. It`s possible that you will find surprises again. Count in that with the vfet the amp has a higher output impedance and will drive lower loads more difficult than the mosfet version.
Now I think you are aware that if you want to get 100W into 2r and all of them in class A you will need to bias your amp close to 3A which is quite difficult from device SOA pov and dissipation pov.
First of going the route of biamping I think it`s worth checking the impedance for the group of speakers(in a speaker) you want to use. It`s possible that you will find surprises again. Count in that with the vfet the amp has a higher output impedance and will drive lower loads more difficult than the mosfet version.
-Blame Pa that there are no Limits to my Greatness
-Schultzsch wrote what's needed
either build properly encased XA252, or change your speaks
recipe for Ease of Life (Geezer age) is - efficient and sensitive speakers
@zm The problem with the efficient speakers.... everytime I am convinced you are right, I drag the Maggie 1.7s from the wall, place them four feet out into the room, warm up the amps and start listening.
I once made the strategic error of hooking up the SissySIT to them.
How about an XA252-SIT-Turbo-V3?
I once made the strategic error of hooking up the SissySIT to them.
How about an XA252-SIT-Turbo-V3?
Proper monoblocks it will become! 🙂 It's what they deserve anyway, right? Besides, it works well with susy dual mono Iron Pre.
I will start this autumn with the amp, and as always, first plans are made for monoblocks (in my head)... if possible...
So, your Mightiness, is it okay to mount the big pucks to the heatsinks left and right and use some short and thick wire (similar to the Scryer's big fat FET) to connect them to the board?
So, your Mightiness, is it okay to mount the big pucks to the heatsinks left and right and use some short and thick wire (similar to the Scryer's big fat FET) to connect them to the board?
A2 levels of power.... 200 wpc into 4 ohms, and pray I don't go nuts and get the 3.7s.
SIT-200.8
I suppose there is always the F5T-V3... and the bridged F4s.... Mind you, I'm having a blast with a pair of 90db/w english speakers with the SissySIT... as you say, efficient speakers are fine and with the Entec woofers they rock, baby.. they ROCK.
...BUT, the Maggies are intoxicating. Indeed, planars are, IMHO, the best speaker. Sure, a PITA to live with, but, but... we are audiophiles... That little SissySIT drove the 1.7s into heaven, at 8... not 11.
yup, gate resistor ditto to gate contact on case, properly heatshrinked with wire
if XA252 SIT is in case, P channel mosfet stays with PCB, SIT goes on flying wires
XA252 will stay as is, give or take 5-10V of rails, so power changed accordingly
again, Bridged/Ultrasymmetry/SUSY/BigBadaBoom XA252 is half done - pcbs on shelf, several things on list being on top of that
in a meantime, buy 200.8
XA252 will stay as is, give or take 5-10V of rails, so power changed accordingly
again, Bridged/Ultrasymmetry/SUSY/BigBadaBoom XA252 is half done - pcbs on shelf, several things on list being on top of that
in a meantime, buy 200.8
How many Tokin transistors will the BigBadaBoom need? Might as well go get them now?
200.8... I'd have to sell my house. Us R&D guys are not doctors, lawyers or high flying politicos. In the Honda and Seiko crowd, you understand.
Who buys XA200.8 anyhow?
@Plott I heard the Wilson WAMM Chronosonic with top of the line D'Agostino amps.... Not impressed at all. But now we're really going off the rails.... sorry... it's just that sound of ZM's ( with NP in there ) SIT design with the Maggies simply floored me. I can't wait 'till I got the XA252SIT in the room.
Thanks guys.
Oh... SUSY/BigBadaBoom... now, that's a name I can proudly show up.... I guess I'll just have to wait.
"What's that?"
"Oh, that's a SisssySIT"
.... "WTF?... hmm.. and WTH is that?"
"Oh, that's a BabelFish"
"Hrmphh... well, you sure have a Plethora of weird things on the shelf!"
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Thanks! I will build the MOS only version, so the IXYS will go to the heatsinks with wire, and no mosfet on board.
existing XA252 is having either N mosfet+P mosfet, or Schaded N mosfet+ P mosfet or SIT + P mosfet, per channel
BigBadaBoom is having twice that per channel
go figure
pretty much yes, even of Chicken as ZM would mount gate resistor ditto at mosfet case, heatshrinked with wire coming from pcb
I mean - that's one of options, having T bar on heatsink
if heatsinks are normal flat, pcb should be mounted flat on one heatsink, with flywires for second mosfet on second hsink