John Curl amp

[AndrewT]

I am forced to reply, "Hell, honey, have you had your DNA checked? I might very well be your father!"

that could be my new byline. Can I borrow it?

 

[GRollins]

As long as you return it in good condition when you're finished with it...

Grey

 

[MikeW]

If there are no other suggestions I will finish up some of my other projects. Thanks for all your insight.

 

[PMA]

So - what is you conclusion, Mike?

 

[MikeW]

It was a learning experience.
Not a bad sounding amp in the end.
Dimitri has some nice equipment. Thanks for the boards.
Sigurd is very gererous.
PMA knows alot more about amps than me.
John Curl can be helpful.
Time to move on to other projects

 

[HKC]

Hi All

Would anyone please tell me if it is ok to eliminate the 5uF input capacitor as my JC-2 clone pre-amp already has a 2uF coupling capacitor at it's output.

Thanks

 

[bear]

yes, but you run the risk of putting the amp together with a source that has DC offset or output, then poof! Well maybe not poof, but you could develop some serious DC output from the amp... better to be safe than sorry.

_-_-bear

 

[john curl]

It is best to add servo.

 

[HKC]

yes, but you run the risk of putting the amp together with a source that has DC offset or output, then poof! Well maybe not poof, but you could develop some serious DC output from the amp... better to be safe than sorry.

_-_-bear

Hi bear

For safety purpose I think the input cap is necessary. There was an accident. I damaged one of my JVC woofer last week when I by-passed the output cap of my JC-2 clone pre-amp and now it needs re-cone service. But without the output cap which is a 2.2uF Wima MKP10 I feel the sonic quality of the pre-amp sounds better. The sound is more natural with no coupling caps.

Best Regards

 

[HKC]

It is best to add servo.

Hi Mr. Curl

Thank you for your prompt reply again.

It is a good idea to add servo. It would be great if you can send me the schematic.
By the way, does a 500VA 25V x 2 (this is the closest voltage I can source from Farnell & RS) toroid transformer good enough for one channel?

Best Regards

 

[HKC]

My pcb layout of John Curl's JC-3 power amp base on original circuit published except I eliminated the 5uF input capacitor as my JC-2 clone pre-amp already has an output cap.

JFets at the input stage will be 2SK170BL/2SJ74BL
Power transistors will be MJL3281/MJL1302 and the rest MJE15032/MJE15033. These transistors will be mounted on heat sinks.
Size of pcb is 5 x 3 inches.

 

[HKC]

3D image of pcb

 

[HKC]

This is the schematic:

 

[MikeW]

This amp should not be built to this schematic. There are improvements to be made. John has given hints along the way. Dimitri also has some improvements. It will no longer be a JC-3 but will sound better.

 

[HKC]

This amp should not be built to this schematic. There are improvements to be made. John has given hints along the way. Dimitri also has some improvements. It will no longer be a JC-3 but will sound better.

Hi Mike

Thank you for your comments.
Do you have the final schematic for me to study before I go ahead to make boards?

Best Regards

 

[HKC]

JC-3 pcb just received:

 

[HKC]

One of the members from the largest diy forum of China building JC-3 using the boards I sent him.

 

[finwbu]

like here ??

http://shop.diyresearch.net/product_info.php?products_id=106

 

[HKC]

This is a JC-3 kit from Taiwan. A very nice pcb design.

 

[john curl]

And people can't understand why I don't publish my latest schematics!