Group Buy for the Through Hole Folded Cascode CEN IV boards

[secanbj]

hirscwi - 1
Kokanee - 3
samoloko - 2
cristianr - 1
tistvan2 -1
madeleeuw - 2
Paddygarcia - 1
av-trouvaille - 1 or 2
RickRay - 1
manniraj - 1
obh - 1
odessamarin - 1
DtotheG - 1
darrr - 1
tadek -2
ihear21khz (David) - 1
asanden - 1
swak -2
nopants - 2
secanbj - 1

Reserved by XEN Team - 8

 

[baggerbole]

hirscwi - 1
Kokanee - 3
samoloko - 2
cristianr - 1
tistvan2 -1
madeleeuw - 2
Paddygarcia - 1
av-trouvaille - 1 or 2
RickRay - 1
manniraj - 1
obh - 1
odessamarin - 1
DtotheG - 1
darrr - 1
tadek -2
ihear21khz (David) - 1
asanden - 1
swak -2
nopants - 2
secanbj - 1
baggerbole - 1

 

[Vunce]

hirscwi - 1
Kokanee - 3
samoloko - 2
cristianr - 1
tistvan2 -1
madeleeuw - 2
Paddygarcia - 1
av-trouvaille - 1 or 2
RickRay - 1
manniraj - 1
obh - 1
odessamarin - 1
DtotheG - 1
darrr - 1
tadek -2
ihear21khz (David) - 1
asanden - 1
swak -2
nopants - 2
secanbj - 1
baggerpole - 1

Reserved by XEN Team - 8

 

[EUVL]

Only 2 sets remaining for batch 2.


Patrick

 

[codyt]

Thanks everyone.

I’m using a Salas Ultrabib for power. On all of the jfets I was able to provide near perfect matching. The bipolars were matched by polarity, with a slight increase in HFE on one side. The mosfets were the biggest challenge, but I was able to compensate with provided instructions.

Straight of the gate I was in the 30-35mV range of positive offset. Ended up using 300-400K in resistance to compensate, per instructions. I’m now around 4-6mV positive, and I’m sticking with that.

Patrick, good catch - I completely forgot the thermal compound. I’ll address that soon.

 

[codyt]

Great job Cody, I won't be attempting my build till the holidays, but would surely appreciate any pointers you can give the rest of us.

The only real tip I would have is to stock up on the smaller SMD parts. The gate resistors (0603) are the smallest SMD I have tackled, and I can't imagine (myself) being able to go any smaller without some proper tools.

 

[codyt]

Here’s an underside pic.

 

[EUVL]

After some more practice, I am sure you can go down to 0402.
Need suitable tools and magnifying glass.


Patrick

 

[woodturner-fran]

Again, well done @codyt !! Don't forget to post your listening impressions when you have time.
************************************

Folks - something that came up in conversation. Its almost hard to go wrong with the placement of resistors and caps.... but bear in mind that the boards are mirrors of each other. That means that some components are oriented differently on each board. Its far easier to double check this before you solder a 3 legged bug 😉😎!!

 

[codyt]

It’s everything I hoped for 🙂 I haven’t measured THD or anything, but the level of clarity and detail suggests that it’s a fair bit lower than the Zen IV it has replaced. It’s quieter, uses more manageable 15V rails, AND doubles the output. Dynamics are better.

All in all, it sounds like a new, improved Zen (which is exactly what I wanted!).

Happy camper 👍

 

[RickRay]

@EUVL I've got a good magnifying system, any recommendations on specific tools for the 0602 and 0402 parts? The tweezers I have need replaced, for one thing they have became magnetized.

 

[EUVL]

You need 0.3mm diameter solder and a 420°C soldering iron with very pointed tip.
Best to use Metcal or similar when the heat is generated right at the tip by HF.


Patrick

 

[EUVL]

but the level of clarity and detail suggests that distortion is a fair bit lower than the Zen IV it has replaced. It’s quieter, uses more manageable 15V rails, AND doubles the output. Dynamics are better.

As explained in the first page of the pdf in post #1 :
https://www.diyaudio.com/community/threads/folded-cascode-cen-iv-with-fixed-rails.389776/


Patrick

 

[CV]

hirscwi - 1
Kokanee - 3
samoloko - 2
cristianr - 1
tistvan2 -1
madeleeuw - 2
Paddygarcia - 1
av-trouvaille - 1 or 2
RickRay - 1
manniraj - 1
obh - 1
odessamarin - 1
DtotheG - 1
darrr - 1
tadek -2
ihear21khz (David) - 1
asanden - 1
swak -2
nopants - 2
secanbj - 1
baggerpole - 1
cv - 1

Reserved by XEN Team - 8


( 1 set added above XEN team)

 

[woodturner-fran]

Nearly there with batch 2

 

[codyt]

I’m tempted to buy another set - if someone is on the fence, you’d better get signed up fast… 🙂

 

[kumori]

hirscwi - 1
Kokanee - 3
samoloko - 2
cristianr - 1
tistvan2 -1
madeleeuw - 2
Paddygarcia - 1
av-trouvaille - 1 or 2
RickRay - 1
manniraj - 1
obh - 1
odessamarin - 1
DtotheG - 1
darrr - 1
tadek -2
ihear21khz (David) - 1
asanden - 1
swak -2
nopants - 2
secanbj - 1
baggerpole - 1
cv - 1
kumori - 1

Reserved by XEN Team - 8


( 1 set added above XEN team)

 

[EUVL]

Batch 2 fully subscribed.


Thank you for your interest,
Patrick

 

[woodturner-fran]

Just to give a status update on where we are at with GB2 - right now I am waiting on boards to be delivered, they will likely be here in a day or two. You will hear from me first by PM to get your details - but nothing before the start of next week......

 

[nopants]

Are there any Idss requirements for the JFETs? I looked through this thread but if there's another reference for more reading I'd love a pointer