I'm going to build a Pass XOno.

[jacco vermeulen]

Chinese fortune cookie says : better a whole poor finger, than half a rich finger.

 

[Gyuri]

Yeah, and that finger became richer with a new experience.

 

[kamis]

Did anyone try DC servo control with Pass X-Ono?

 

[Zen Mod]

outa fashion

not approved by audiophools

 

[Gyuri]

Yeah, I'm trying this.
Use the screwdriver.

 

[kamis]

Yeah, I'm trying this.
Use the screwdriver.

I am not able to stabilize DC offset using trimmer pots in my X-Ono. I am going to use output caps or op-amp servo, if possible. 100 mv is too high.

 

[sakellogg]

i wouldnt worry about it yet till you get it in a case. i found that i had to tweek put the lid on wait for some hrs, then do it again. it warms up inside my case and everything stablizes.

ill check my notes on the V refrences but, i dont know if ill have them. but i can open her up n get them.

also, if you have to keep the caps in, no big deal. i couldnt tell the diffrence if i had to!

most importantly...... she is a sweet sounding little girl isnt she!!?

 

[Gyuri]

I have some questions about XOno.
Am I right, that MC input fets are running at about 4mA?
Ideal voltages accross R45,46,47,48 88mV?
Mine voltages are between 84-91 mV

And what about Q15?
Mine is there now a 2SK170BL, running at about 3,6mA 200mV/56Ohm.

And how about D5?
Accross legs I can measure about 1.74V, 1.72 on the other side.
I get voltages 1.13V and 1.11V on R67, 1.14 and 1.12 on R53.
Is it good, or I must search better LEDs?
I don't want to change resistors.
The 0.35V on R33 present, a little bit changing on the timeline.
DC offsets are somehow bouncing histerical as I wrote earlier, but I don't get bigger than say +- 0.1V.

The whole thing very quiet, dynamical, airy with good bass, middle and treble.
What can I say?
It's a perfect amp.

What can I do to make it better?
Maybe I should put it into the boxes.
Only that poor finger.

Wacky

It seems to me, my questions are don't understandable and/or too difficult.

 

[kamis]

Ideal voltage across R45-48 should be around 75mv, but yours are tolerable.
LED voltage is under tolerance as well as others.
Input J-fet matching is important.

 

[Gyuri]

Thank you for your answer!
So I does not have to worry too much.
(For this, at least.)
I don't think I would get closer match on Q10-13 than above 84-91 mV on source resistors.
I have 20 2SK170GR what I doesn't measured yet,
but I don't think I would get closer match than I have now.
And I'm lazy.
I'd rather let it to sing to me this particular equipment.

And how about Q15?

 

[brianco]

Can't offer any advice Gyuri.........I have not yet tested mine.

But have you cased yours yet? And is the finger now improved? Hope so.

 

[Gyuri]

I do not want to interrupt the music.
So I'm afraid this is not let in a box for a while.
Yes, my finger is wiser now.

 

[kamis]

Thank you for your answer!
So I does not have to worry too much.
(For this, at least.)
I don't think I would get closer match on Q10-13 than above 84-91 mV on source resistors.
I have 20 2SK170GR what I doesn't measured yet,
but I don't think I would get closer match than I have now.
And I'm lazy.
I'd rather let it to sing to me this particular equipment.

And how about Q15?

All Pass Ono and X-On clones are based on Pass Ono service manual , which had no J-Fets Idss group designation for 2Sk170 and 2SK389 . Only owners of manufactured units know real idss groups. Nelson Pass once said that input J-fets are from the BL group! I am not sure how they got 15 V on input fets drains.I kindly ask Ono and X-ono owners to tell us the true .
Ralph Stens uses BL for Q15, and you should follow your PCB designer.
It is also MM stage R5 value which is various in clone units.Some use it grounded , some tied to V- , I really wish to know how Pass assemblers solde red it.

 

[Gyuri]

Ralph Stens uses BL for Q15, and you should follow your PCB designer.

Yes, I have done it so.
But there is a difference between BL and BL.
Note that the majority of my 2SK170GRs was far below the value of 80 mV.

 

[kamis]

Only Wayne Colburn knows the answer.
What is your R5 mm stage resistor value?

 

[kamis]

Original X-Ono have 7915 and 7815 voltage regulators with resistive dividers to raise voltage to 30V. Regulated voltage is filtered by 5R+3300 microfarads RC filter. So if you wish the best phono ever according to Absolute Sound, follow original schematic.

 

[Gyuri]

According to Ralph's advice I have 15k resistors at R5 position.
But I try two 15k parallel at that position, LED voltage doesn't change.
I don't want to change R67 and R53, so I think, I will play with different LEDs, what I have now.

 

[kamis]

According to Ralph's advice I have 15k resistors at R5 position.

In his latest revision R5 is 10K tied to GND! Total confusion!

 

[Gyuri]

After all, it does not matter.
The device is excellent,
While I'm not listening to this, the input signal was a sweep.
I believe now it is even better.

 

[wayne]

The original units all used BL devices. The voltages came from a single unit and are not actually typical in the front end. You may find that you can adjust input cascode base resistors for better performance. Also use .5 watt resistors to float the regulators. These are still pretty good units even though they aren't made any more.