Hifisonix kx-Amplifier

[supernet]

kx-Amplifier PCB's are back in stock at Jim's Audio here:-

Hifisonix kx Low Dist ,Wide BW 25 W Class A, 50W classAB CFA Amp PCB set stereo! | eBay

The new batch of boards are as before, but now include gold plating.

As always, any questions, let me know.

Any chance to make an option 2 kx boards + ripple eater PSU?

 

[Bonsai]

Sorry supernet, unfortunately not at this time - this is how they are configured in Jim's Audio Store. But you can always start with the standard board set and later upgrade.

 

[thimios]

Hi Bonsai,are you think that is time to recicle my sx to save parts for this new KX?

 

[Bonsai]

Hello thimios, You can use the original PSU, but you do need 4-5V more on each PSU rail to get the full benefit - the EF2 kx-Amp output stage drops more swing than the original sx-Amp.

 

[thimios]

Hello thimios, You can use the original PSU, but you do need 4-5V more on each PSU rail to get the full benefit - the EF2 kx-Amp output stage drops more swing than the original sx-Amp.

but you do need 4-5V more on each PSU rail to get the full benefit
Are you speaking about full power or something else?

 

[Bonsai]

Full power. You lose about 2 volts on an sx-amp and another 4 to 5 on top of that for the kx at full power into 8 Ohms.

So sx - I recommended +-22~23 VDC

for kx I recommend 27~29

Naturally, you will need decent heatsinks for class A operation

 

[thimios]

Full power. You lose about 2 volts on an sx-amp and another 4 to 5 on top of that for the kx at full power into 8 Ohms.

So sx - I recommended +-22~23 VDC

for kx I recommend 27~29

Naturally, you will need decent heatsinks for class A operation

Naturally, you will need decent heatsinks for class A operation
That's why i want to recycle my SX

 

[druif]

Hi,

i was looking at this KX amplifier, very interesting...i'm not very experienced but i would like to gather some information...

first of all: many thanks to the designer for sharing all the details and instructions!!!

How about matching the transistors, do these need to be bought a lot and be matched?

As far as concerning for;
the output transistors NJW3281/NJW1302.
the driver transistors KSA1220A and KSC2690A
the TO-92's

or just buying the nessecary quantity and the right type?

thanks in advance and greetings!

 

[Bonsai]

Hi druif

No need to match transistors on the kx-Amp. Just buy the required quantity and you will be ok.

 

[druif]

Hi Bonsai,

That's a big plus, saves time and effort...and costs

Thanks for the quick response!

Greetings

 

[Bonsai]

 

[stocktrader200]

ripple on the main output rails of a few volts under load makes no difference if the amp's VAS stage is properly regulated.

 

[druif]

PCB's are ordered at Jims'...i'm going for it.

Hi, stocktrader200 thx!

 

[poseidonsvoice]

Hifisonix website appears to be done, any ideas on what is wrong?

Thanks,
Anand.

 

[Bonsai]

No, its working for me via my phone. Please try again and if you have a problem let me know.

 

[Bonsai]

ripple on the main output rails of a few volts under load makes no difference if the amp's VAS stage is properly regulated.

The kx-Amp PSRR without the optional cap multiplier PSU is >70 dB at LF and better at HF - typical figure for a CFA. With the optional cap multiplier PSU, its about 30 dB better.

VFA PSRR is usually about 20 to 30 dB better than a CFA.

 

[pitbul]

@Bonsai
https://hifisonix.com is down for sure, there is something wrong.

 

[Mark Johnson]

Here's what I see on Saturday at 11:13 in San Francisco. That's 19:13 in London.

_

 

[pernugget]

DOES work for me in SFBay area time zone.

 

[bambadoo]

Shift+F5 (shift+reload) worked for me. Fail at first, then ok.