Zen Variation 9

[wg79]

Hello.
I am new here. I joined because I have a 'little' problem with my Zen v9. I have made Zen v4 and it sounds well but I found LU1014 and I wanted to do v9. I know it's an old contruction but it should sound much better. I made PCB according to fig.8 of this article Zen Variations 9 | Pass DIY but I can't set any current by setting P1.
I don't understand a way of control Q1. I have 44V instead of about 23V on a drain of Q2. It means there is no current. I can set 3V on drain of Q1 but there is still no current. Q1 is stuck. But it's connected to ground by R17+R7. Lu1014 is a N-channel transistor so it is switched off by grounding. I made a test schema according to fig 10 and if its gate was connected to ground Q1 didn't conduct. It conducted only if I got + to gate.
So if you were so pleasant and patient please explain it to me.

 

[Zen Mod]

LU1014 is JFet , normally on part , so you need negative at gate to shut it off

you probably have fake one , if you need positive voltage at gate to conduct

if you did something , and it doesn't conduct with article - problem is at your side - either dud part or implementation

 

[AndrewT]

............. Lu1014 is a N-channel transistor so it is switched off by grounding.

Lu1014 is a depletion mode FET
Depletion and enhancement modes - Wikipedia

I made a test schema according to fig 10 and if its gate was connected to ground Q1 didn't conduct. It conducted only if I got + to gate.
So if you were so pleasant and patient please explain it to me.

you are describing an Enhancement mode FET.
Looks like you have bought fakes or you are not testing them correctly.
Vertical mosFETs are available very cheaply. All the cheap ones are enhancement mode. These are what get used to make fakes of the more expensive Laterals and jFETs.

 

[wg79]

Thank you for your fast reply.
I suppose they are fake (China). I checked PCB twice and I found a mistake before. C1 capacitor was mounted inversely and it conducted. Then I was able to set the current because I give + to gate of Q1. But R7 resistor was burning.
Where can I buy real LU1014.

 

[Zen Mod]

either here or here

as far as I know , those are genuine

 

[wg79]

Thank you again.
There is a saying in Poland - 'cheap meat is eaten by dogs' and it is still actual (my example).

 

[Nelson Pass]

If someone with a U.S. address wants to organize distribution, I am happy to
donate a quantity of these Jfets for DIY. Match them yourself....

 

[wg79]

If someone with a U.S. address wants to organize distribution...

It sounds great but there is IF. Anyway thank you for it.
All of you helped me a lot. I didn't realize that quite cheap elements and not so common might be fake.

 

[woody]

I also picked up a few fake ones from ebay.

 

[Dennis Hui]

That's unfortunate.

I had heard of folks getting parts that appeared used but were otherwise OK.

I would be more than happy to volunteer to measure and distribute parts, but
alas I'm in the Great White North.

 

[woody]

Now if you are in a hurry and don't mind spending a few $ Deepsurplus still has
a few. And they are indeed real. He bought a lot of them when the suplier went
bankrupt. And the few I bought from them test out good!

http://www.deepsurplus.com/Electronic-Components/LU1014D-JFET?range=49,51,51

 

[wdecho]

I've bought from deepsurplus and also on Ebay from China and both were real LU1014's. Ebay sellers can be a gamble unless known to sell original components though.

 

[wg79]

Lucky you.
I hit fakes at once. I will try to buy them from deepsurplus but it takes time to sell them to Europe.

 

[Zen Mod]

boyz , I'm not in States ..... so somebody (else) must chime in for matching and distribution , if you want to take them from Papa ........

 

[wg79]

Finally I have made it. Special thanks for one of you.
I have one more question. Which preamp would be the best to Zen9?

 

[Zen Mod]

upcoming Iron Pre , what else ?

 

[wdecho]

My buffer of choice is the B1 version 2. My pre with gain choice is the LSK pre discussed at the BAF. These 2 are my favorites of the many SS ones I have built. Many others are more than adequate as well.

 

[kinku]

Papa, I am willing to take them and match and distribute them.

 

[Zen Mod]

send him an email , just in case

 

[kinku]

Just did. Thanks ZM.