FirstWatt J2

[gary s]

A very nice build Patrick, I am looking at getting one of those exact enclosures on ebay.

Can I ask for the J2 circuit you had in post #1274 way back, what was the value of the pot Rdg under Q1?

 

[Itsmee]

...I am looking at getting one of those exact enclosures on ebay...

Have you got a link please

 

[gary s]

I believe this is the enclosure.

JC3 circuit power amplifier aluminum chassis enclosure with both side radiator | eBay

Cheers,

Gary..

 

[EUVL]

You can determine Rdg yourself by measuring off board with your own NJFET to get 6mA.


Patrick

 

[EUVL]

Classic engraved MARK LEVINSON ML2 full aluminum amplifier chassis enclosure JC3 | eBay

But without the ML marking.
Special order from Breeze Audio direct.
And of course you can use 2x Tx for fully dual mono build.
We use 1x 300VA only because we have them in the store.

Again, no need for 70µm copper PCBs.
Actually better than 70µm as 2x 35µm has less inductance and skin effect.


Patrick

 

[EUVL]

Protection circuit is here :
Simple Speaker Protection for Power Amplifier with Balanced Outputs

I am old fashioned.
I prefer gold plated mechanical relays to SSR's.
But you can use whatever pleases you, including no protection at all.


Patrick

 

[Morde]

Great work Patrick! What is the purpose of the relay between cap multiplier and amp board? Is it for some form of standby functionality perhaps?

 

[Itsmee]

I believe this is the enclosure...

Thank you.

 

[EUVL]

Not that one.
See post #1685.


Patrick

 

[EUVL]

> What is the purpose of the relay between cap multiplier and amp board?

To switch off the regulated DC rails to the amp.
Not must-have.


Patrick

 

[Itsmee]

Thank you Patrick, I won't be buying either - same reason I wouldn't buy the First Watt chassis I have seen in the past; If it had a plain front panel, that would be a different matter.

 

[EUVL]

Mine has a plain front panel.
You can always ask the supplier.

The one linked by gary s is engraved with "WeiLiang Audio", which is the same as Breeze.
Again, cost nothing to ask if engraving can be skipped.


Cheers,
Patrick

 

[EUVL]

Someone asked for a larger image of the PCB.
Here you are.


Patrick

.

 

[twitchie]

These are the cases I bought. The heatsinks and internal tunnel are the same as Patrick's. The only thing I would ask to be changed is the power switch on the front panel.

3415 all aluminum power amplifier on both sides of a small cooling chassis can be installed Wei Liang JC3 circuit-in Amplifier from Consumer Electronics on AliExpress

I printed out the UMS template and tape it on the heatsinks and punch the holes and drill those on a press. Tapping is the tricky part but it's not difficult.

 

[gary s]

Thanks for the AliExpress link twitchie on that enclosure - much cheaper there than on ebay, but then again that is no surprise these days.

How is the overall quality of the enclosure can I ask. I note your comment on the front panel power switch, I can live with that.

Cheers,

Gary..

 

[JeffYoung]

Someone asked for a larger image of the PCB....

I like those ring connections. Are they just bolted through, or are you using some sort of solder-mounted threaded studs?

Thanks,
Jeff.

 

[EUVL]

Brass screws and nuts, both soldered to PCB after tightening.
Usual practice for our F5X and F5XP designs.
Not practical for commercial production.
Perfect for DIY.


Patrick

 

[JeffYoung]

Ahh... so there's another 1/2-height nut under the ring terminal that we can't see?

Very clever solution.

 

[EUVL]

Full height. No special parts required.


Patrick

 

[woofertester]

J2 variant with IXTH16N50D2 current source

I am looking at the behavior of the IXTH16N50D2 as a current source for a J2 variant. At 24V, the source resistance to give 2A bias is around 0R8. The current is self-biasing with a reasonable tempco.

Would this make sense as the Mu follower current source for a J2? The idea is to skip the need for the opto bias.

I have the SS parts from Euvl's group buy.