LuDEF

[tombo56]

For proper thermal transfer, my intention is to mount LU on adapter board just like regular TO case would be, by soldering solid wire vertical pins, instead of long flexible wires. Two 3.5 mm holes at approximately 8 mm from PCB edge (+- 10 mm horizontally from existing hole) are at right position and wide enough for screwdriver.

 

[Attila I]

so we have a jfet soldered to a heat spreader of 1.5mm alu - bolted to a big heatsink with some thermal goo inbetween - and that's not enough for this tiny bugger - even if I only use the top hole????
I am not scared!
cheers
A.

 

[Zen Mod]

 

[Attila I]

at first start right channel acted weird - found zd104 in reverse - fixed.
now both channels dial in pretty easily - work within specs on spot!
Lu on daughterboard is 5-6 degrees above ambient - no smoke...
still have to check for musicality - pics to come.
cheers
A.

 

[Zen Mod]

 

[tombo56]

Some progress.

 

[Zen Mod]

 

[tombo56]

Nooo, I’ve put diode instead R122.

Just joking. It’s deliberately put there and it is not a diode at all.

It is a CCS modification that improves it’s PSRR by + 30 dB, bringing it from actual 70 dB to about 100 dB.

https://www.diyaudio.com/forums/solid-state/376744-improving-simple-ccs-psrr-30-db.html#post6778920

 

[Attila I]

As ZM is growing momosyllabic I will speak about my LUDEF impressions.
I like it!
My beloved M2 is now only second best amp.
Thanks to the donator Nelson Pass, to Will Goloveyko for matching and all
and last but not least to the allmighty Zen Mod.
Thank You All!
A.

 

[tombo56]

I believe that woofertester was doing the matching and Will was doing the GB logistics.
Anyway HUGE thanks to both of them and to Nelson for donated LUs.

 

[Attila I]

That lapse was not intentionally, sorry and special thanks to woofertester.
Cheers!
A.

 

[wg45]

Thanks. Glad to see the devices and parts are being used.

Yes, Woofertester did all the matching and I handled the GB distribution.

Most of all Papa donated the Jfets and Zenmod created the LuDef!

 

[Zen Mod]

Blame Pa

LuDEF is just fancyschmanzy F3

 

[grataku]

Nooo, I’ve put diode instead R122.

Just joking. It’s deliberately put there and it is not a diode at all.

It is a CCS modification that improves it’s PSRR by + 30 dB, bringing it from actual 70 dB to about 100 dB.

https://www.diyaudio.com/forums/solid-state/376744-improving-simple-ccs-psrr-30-db.html#post6778920

Just a diode instead of the 6k8 resistor?
What kind of diode?

 

[grataku]

cinemags are shipped!

 

[Zen Mod]

R122/R123 are anti-oscillation thingie


I didn't even think of improving LT3092 CCS-ity

 

[tombo56]

Just a diode instead of the 6k8 resistor?
What kind of diode?

I didn’t check if modding the Zen Mod is legal here.
If there are no legal consequences, with modifications there are increased chances for trouble.

Proper way is to first build amplifier as designed. If everything behaves and amp sings, only then is OK to proceed with eventual modifications.

Everything about mentioned ‘diode’ is explained at the linked thread. It is, so called, current regulator diode (in fact packaged JFET CCS). Replacing CCS biasing resistor, which is R112 (made a typo) with this ‘diode’ reduces effect of voltage ripple on base of BJT that regulates current.
Adequate parts are Semitec E-202 or E-272 ‘diodes’.

 

[tombo56]

R122/R123 are anti-oscillation thingie

I didn't even think of improving LT3092 CCS-ity

And you are right. Absolutely no reason to meddle with LT3092.
It was R112/R212 and another CCS.

 

[zman01]

cinemags are shipped!

grataku,

Do Cinemag have the transformers in stock or these were built to order?

 

[Zen Mod]

if R112, all good

Modding ZMod id always welcome!