New Hifisonix KX2-Amplifier

[Bonsai]

Sorry - I only just saw this.

MJW will work ok 👍

 

[oloppolo]

Hi Bonsai, I built kx2 and am very happy with it. I had started building two kx boards before the kx2. I would like to complete kx but I don't have large heat sink. What value of R1 do I need for AB bias in kx? I am very grateful for your work.

 

[Bonsai]

Olopollo, I’ll come back to you tomorrow on this.

 

[Bonsai]

Olopollo,

To run the kx-Amplifier in class AB, just leave switch J8 OPEN. Then you have R8 = 4.7k and R18 = 33k. This should give you a reading of ~200mV across [R12 + R13] which will give an output bias current of 300mA +-50mA. This will give a total power dissipation of around 30W per channel. If that is still too high for your heatsink, remove R18 altogether.

VERY IMPORTANT: YOU MUST CHANGE R5 AND R4 TO 1K!

 

[Bonsai]

It looks like Jim's Audio is no longer trading on eBay. If this is indeed the case, I will supply kx2-Amplifier boards from the Hifisonix shop. I'll update later in the week.

The original nx-Amplifier will soon be replaced by an upgraded and better-performing nx2-Amplifier, so I don't propose putting the old nx-amplifier PCBs in the Hifisonix shop.

 

[passive420]

Can't say I blame him Andy, Ebay have recently updated their fees again. Your original SX and NX boards alongside your other modules are still available from his online store.

https://jimsaudio.com/15wx2-class-a...on-sx-amplifier-2-0-current-feedback-pcb-set/

https://jimsaudio.com/100wx2-ovation-nx-current-feedback-amplifier-pcb-set-new-version-2-0/

 

[Bonsai]

Ok - that’s good to know. I will update the links on my website. Thanks for that!

 

[oloppolo]

Olopollo,

To run the kx-Amplifier in class AB, just leave switch J8 OPEN. Then you have R8 = 4.7k and R18 = 33k. This should give you a reading of ~200mV across [R12 + R13] which will give an output bias current of 300mA +-50mA. This will give a total power dissipation of around 30W per channel. If that is still too high for your heatsink, remove R18 altogether.

VERY IMPORTANT: YOU MUST CHANGE R5 AND R4 TO 1K!

I am very grateful to you

 

[passive420]

Andy, sorry pal just found Jims store on ebay. He's still there by the looks. Your website links are simply out of date it seems.

This is a good deal on the KX2 with PSUs for dual supply ( in my basket mate ):

https://www.ebay.com/itm/225986750836?hash=item349ddc2974:g:CfAAAOSwTcNiQFOa

 

[Bonsai]

👍 I’ll update the links later today

 

[Bonsai]

I've updated the links to Jim's Audio for the kx2 PCB's.