How to Pass a little time ...cont

Looking at the first pic, I never would have guessed the chassis was cobbled together bits. Amazing what people with talent can do...

 

I think this is going to be the last solid state amplifier I build, I would have stopped with the one I use currently but I started collecting the parts for this amp prior to COVID and the pandemic put a damper on the development and availability of this amp which is what I had intended to build all along – my current amp, the balanced M2OPS was a very pleasant accident and I have been very happy with its performance. The amp in question is a derivative of the PASS XA25 – called the XA252SIT – it is the creation of the crazy ZenMod, naturally inspired by NPs design. It is a beefy 40W class A amp - full details available here ( link ) - I am building the SIT version with the industrial TH51s



I picked up the output devices a very long time ago – they are now virtually unobtanium , and have picked up parts as I saw them over the past few years. Dual 12A 24VAC transformers for a full dual mono implementation. Mosfet switched output protection for very quick shutdown in case of failure and to protect my speakers ( I used the same boards in my F4 - they are very well designed, not cheap but significantly cheaper than a new pair of speakers). A slow start and timed startup board to support both latching and momentary power switches. I picked up 8 beer can capacitors ( 50V 56000uF ) with the idea of building a CRC supply filter but they were massive and filled the entire chassis , so I switched gears to using a mosfet regulator for both positive and negative rails.

I had planned to build this one in a prefabbed chassis as a “keeper” amp , but my plans may be thwarted by the massive heat dissipation requirements of the output devices.


I picked up a non-working Sumo Andromeda II that was quickly filled by building the power supply





All rails settle to + and – 33VDC which is perfect for the circuit.


These are the heatsinks I had originally bought for the amp and have put them next to the original andromeda sinks for comparison.



And in relation to the chassis and power supply.




A long way to go , I thought I might have had more time over the holidays but family time was a priority and there are many a cold night ahead as we nestle down for winter in the midwest.

I have a few implementation decisions to make but this will evolve as I complete the amp itself and start to test just how hot these heatsinks get. This beast is going to weigh in close to 60lbs with these beefy heatsinks , so need to think about the practicalities too.

..dB

 

I'm still debating on building this amp, despite having no time to do so and already having built a wonderful SissySIT with the THF-51S (highly recommend this design from Zen Mod!)


I'm halfway through a Wolverine (ultra-low THD;Class A/B) build, which is essentially a wire with gain project; and, I really don't need more amps, but the XA252 SIT looks awesome.

Stoked to see your progress and read any impressions you may be willing to share.

 

I very nearly picked up the wolverine boards but i always gravitate back to Class A , hence the XA252 - I will compare to Sissy when done

 

Curious about your thoughts on the Wolverine when you're done. I have the boards and silicon but that's about it right now.