Krell KSA-100 class A clone:

[hydrovac]

Hi all,
My on going amp build... completed couple of amp projects (Jean Hiraga 30w, Krell KSA-50 clone) recently but was lazy in posting build logs.

The modules:


Trying a new heat sink profile on chassis...


Two heat sinks joined side by side... weighing 5kg per module.

Bottom and back plates 3mm thick...

Face plate 6mm and top plate 3mm...

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[yogibear]

Nice ! How do you source your required dimensions of aluminum plates ?

 

[hydrovac]

Buy bulk sheet and laser cut (job work) to custom sizes.

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[captrajesh]

Super! Having heard the very musical sounding KSA50, can't wait to audition this monster.

 

[arunlouie]

Buy bulk sheet and laser cut (job work) to custom sizes.

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And the heat sinks?

 

[hydrovac]

Module mounting process on heat sink... M3x12mm standoff.

Power transistors clamped with 8mm sq aluminum bar....

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[hydrovac]

Back panel with input, output, IEC mains socket and a 60mm cooling fan...


50A Bridge with fan and PSU raised on standoffs... mains filter and soft start, below on the bottom plate.


Ready for hook up wiring...


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[Nikhil]

Wow! What a monster of an amp!
Would really like to have a listen when it is ready!


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[surfatwork]

Looking really good

 

[sadik]

Great Job Bro. what is the small fan for next to transformer?

 

[hydrovac]

Great Job Bro. what is the small fan for next to transformer?

Heat sink with fan on 50A bridge.

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[lifewater]

Fantastic work Sir. Should be a hell of an amplifier.

 

[hydrovac]

One module wired... checked all the voltages, mains, DC Rails, dc offset, speaker protection... all good for testing.




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[hifimaddy]

@hydrovac Great build, bro. I hope this sounds amazing. I have to ask you, where did you purchase the heatsink? Can you provide me the source?

thankyou
vishnu

 

[hydrovac]

Finally finished setting up two channels bias successfully on KSA-100...
both low and high @ 60mV and 200mV (480mA and 1.6A) respectively. The below readings on high bias.

heat sink temperature... after an hour of playing.

Trafo temperature

junction temp

temp acrylic face plate... need to do some cosmetic finishing on the al plates.

provided a toggle switch for low and high bias option...

slow spinning fan on back panel...

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[yogibear]

What's your ambient room temperature when you took these measurements ?

These days we are facing scorching heat, nearly 45C and all my tube amp irons in storage and even not playing feel hot to touch. It's crazy.

 

[hydrovac]

@hydrovac Great build, bro. I hope this sounds amazing. I have to ask you, where did you purchase the heatsink? Can you provide me the source?

thankyou
vishnu

Thanks vishnu!
sorry for the late reply... got the heat sinks from Himalay Engineering co. (Mumbai)

What's your ambient room temperature when you took these measurements ?

These days we are facing scorching heat, nearly 45C and all my tube amp irons in storage and even not playing feel hot to touch. It's crazy.

The rooms ambient temp was around 34*c

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[captrajesh]

The rooms ambient temp was around 34*c

Sir, with the air-conditioner on, the room temperature being 34°C looks much on the higher side.

I had the privilege of auditioning the amp. While it is as resolving as the KSA50 which was made earlier, two aspects of the sound were striking to me.

One aspect was the micro-dynamics, which were quite palpable. Second was the soundstage; the soundstage was so deep that it was the best that I have experienced at Krishna's place. It's truly an amazing amp. Hope to do a back-to-back comparison with the KSA50 and hear out the differences.