New Hifisonix KX2-Amplifier

[thimios]

Thanks For your feedback Hans - that is indeed a compliment

Hi Andrew, Happy New Year!

 

[Bonsai]

Thank you thimios! Happy New Year!

 

[gudmundur]

Hi Bonsai,
Happy New Year!
I went through the documentation but I couldn't find in what position of J3 (jumpered or not) I supposed to have standard Miller compensation?

 

[oloppolo]

I have driving problems with KX. Argon Audio SOLO dac is not good for KX and not good preamplifier with OPA2132, not good and B1 buffer. Excellent with motorola G52 and Xiaomi smartphones. Advice for me? Thanks.

 

[oloppolo]

Hi!

Pics of the inside and rear please!! It will help some of the newbie builders to this circuit like crispycircuit above…

Best,
Anand.

OK

 

[Bonsai]

Hi Bonsai,
Happy New Year!
I went through the documentation but I couldn't find in what position of J3 (jumpered or not) I supposed to have standard Miller compensation?

Hello Gudmundur

if you leave J3 open it is Miller compensation. If you put the jumper in, it is Transitional Miller Compensation.

 

[Bonsai]

I have driving problems with KX. Argon Audio SOLO dac is not good for KX and not good preamplifier with OPA2132, not good and B1 buffer. Excellent with motorola G52 and Xiaomi smartphones. Advice for me? Thanks.

Hello Olopollo, I don’t understand your question. Can you explain it again?

 

[crispycircuit]

Thx for the pic. Very clean build. I don't understand how the power transformer is wired up. How do you like it in your system? Are you not using the grd. lift on the

 

[wirewiggler]

Olopollo,
Nice clean looking amp, as a suggestion it is good precaution to insulate your primary wiring. The ground lift suggested by crispycircuit will help a-leave any potential hum issues, and if you read over bonsai’s article on ground loops it may help keep the amp quiet with a little movement on the internal wiring.
Bill

 

[andrikstormik]

Good afternoon

Bonsai​

.
I will be very thankful for an answer.
I ask to excuse if before there was an answer in a theme.

as far as is the temperature of transistors of radiator of 70-80С critical warming up in a flow 30-60 minutes ?
what ideas on the temperature of transistors ?
very thankful for an answer.

 

[platon.rado]

Bonsai,what is the KX damping factor???
Thanks

 

[Gvida]

HI

I am new on this thread, I would be interrested to build The KX2 and for that would like to know if there are any French builders who have done this amplifier yet. So if you are concerned by my request please let me know, it will be easier for me to have exchanges in french rather than in English.
Sincerly yours

Geo

 

[Bonsai]

Good afternoon

Bonsai​

.
I will be very thankful for an answer.
I ask to excuse if before there was an answer in a theme.

as far as is the temperature of transistors of radiator of 70-80С critical warming up in a flow 30-60 minutes ?
what ideas on the temperature of transistors ?
very thankful for an answer.

Apologies for the very late reply here.

70-80C is far too hot. For full class A operation 55-60C is the absolute max upper limit. In your case, I’d operate the amp in class AAB mode.

 

[Bonsai]

Bonsai,what is the KX damping factor???
Thanks

The damping factor is ~360 at 1 kHz into 8 Ohms

 

[platon.rado]

Thanks

 

[blacknoz]

HI

I am new on this thread, I would be interrested to build The KX2 and for that would like to know if there are any French builders who have done this amplifier yet. So if you are concerned by my request please let me know, it will be easier for me to have exchanges in french rather than in English.
Sincerly yours

Geo

Hi @Gvida,
@Bonsai just forwarded your request to me.
As I said to him, I didn't build the KX2 but I built the NX, there may be similarities in the build(?). BTW if I can help I'll, please private message me in french, I'll try to do my best to help.
Thanks,
Raphaël

 

[Bonsai]

thanks blacknoz 👍

The kx2 is a derivative of the sx and nx amps so there are a lot of similarities especially in the front end and VAS.

As always, any questions, please let me know.

 

[andrikstormik]

Apologies for the very late reply here.

70-80C is far too hot. For full class A operation 55-60C is the absolute max upper limit. In your case, I’d operate the amp in class AAB mode.

1. amp in class AAB mode +-28V
2. cooling is not little 400мм 150мм 40мм
3. there is a slow warming-up 30 minutes to the temperature 60-70 degrees.
4. thermal balance comes a temperature is a current of rest. current of rest as a mode A class

 

[Bonsai]

If you are in class AAB mode and the amplifier ends up settling in class A mode that would normally indicate the heatsinks are undersized, but your heatsinks for class AAB look ok to me given their size. Are the heatsink measurements you give for one channel or both?

I am away travelling at the moment. On Tuesday I will come back to you to take some measurements so we can find your problem.

 

[andrikstormik]

400мм 150мм 40мм is a cooling size for two channels, general radiator. I set the current of rest for the mode of АВ a strengthener works in ААВ .
I am happy all ок.
large gratitude for a wonderful amplifier.