I'm really sorry Juma if you feel that way .I do not want to hurt your feelings !
Please forge me . If you read my post you can realize my English not the best . I know that is my fault .
I didn't slept the last 24 hours , probably is not the best time to post at on the forum now .
How I said I have a lot to thank to you .
One more time honestly please forgive me .
Now with your last post made it clear !
I do not want to lose your help in any cost ! You and Thanh you guys helped me a lot .
Thank You ! and Thank you !
Now all clear BJT for cascode and I stick with the orig JETs as driver .
Greets
I hope you can forgive me !
If it was not that V FET or JET I 'm sure these misunderstanding from my part it could be avoided .
Please forge me . If you read my post you can realize my English not the best . I know that is my fault .
I didn't slept the last 24 hours , probably is not the best time to post at on the forum now .
How I said I have a lot to thank to you .
One more time honestly please forgive me .
Now with your last post made it clear !
I do not want to lose your help in any cost ! You and Thanh you guys helped me a lot .
Thank You ! and Thank you !
Now all clear BJT for cascode and I stick with the orig JETs as driver .
Greets
I hope you can forgive me !
If it was not that V FET or JET I 'm sure these misunderstanding from my part it could be avoided .
Hi gaborbela,
what do you think of this?
http://www.diyaudio.com/forums/pass-labs/108683-ugs-power-its-u-p.html
what do you think of this?
http://www.diyaudio.com/forums/pass-labs/108683-ugs-power-its-u-p.html
@gaborbela
What is clear is that English is not your first language. That along with a lot of enthusiasm can lead to all sorts of misunderstandings. You have apologized - more than necessary - so just let it rest!
@Everyone.
I do think that some of the posts which have recently appeared on this thread are outside the normally very friendly and helpful posts usually found on the Pass Pages! Remember NP's sign off----
[IF anyone wants to be terse and or generally difficult a couple of other threads I can think of will accommodate that desire!
]Thanks
Too late
It may help me to know just a little about what you tried that didnt work
Number of outputs, rail voltage, value of gate resistors, source resistors
Anythig you can remember
I dont expect much, just smaller things please, and thats the end of it
I love it
Hey Gab
Just one more time. It is JFet not Jet ok.
And Juma was suggesting V grade JFets. The Jfets are graded in to Idss classifications ie gr, bl, and v grade.
If you look at the your Jfets closely you should see one of those classifications stamped on the device. V grade devices have the highest Idss value.
I used bl grade but I measured them to choose a nice matched pair suitable for the task. From memory Idss was around 10mA for my JFets.
The resistor values are not absolutely critical for cascoding, however since Juma has already told you what to use, it would be a bit rude not to take his advice.
The improved simulated performance was from using the higher voltage rails (eg +/-40V) and not from cascoding.
Cascodig was used to protect the Jfets from such high voltage (and increased power dissipation)
Best Wishes, Don't give up just yet
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Hi gaborbela,
what do you think of this?
http://www.diyaudio.com/forums/pass-labs/108683-ugs-power-its-u-p.html
Souce follower at output. Is that an F4X?
I fitted new resistors,and it seems to work.
However I was going to check the bias and offset,but it seems I lost the instruktions,anyone got a link,don´t wanna read the whole tread again..
Sounds extreme... maybe you should check if your solder joints overheat while playing.
The adjustment instructions can be found here:
http://www.firstwatt.com/downloads/F5-om_sm-080527.pdf
That I suppose is not the only thing that happens with cascode
Not from whats written about it
But why on earth you think its rude to ask questions is beyond me
But I like your chin up remark
Just a side remark
You know fore a fact that NelsonPass wants us to experiment and learn
Its not just about copying his designs
Nelson supported multiple outputs
He also suggested cascode
And gave other small hints
Like a good teacher does
But sure, things have gone a bit out of control
But I sure know the question "how do I design the perfect speaker"
There is no answer
But if its about learning, almost anything goes
Its a crime putting limits to the possibility of learning
Theres plenty of that around the world
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I never said it was rude to ask questions.
I said it was rude to ignore or disregard advice after asking for help
As a scientist I am all for experimentation. If you have read my posts hopefully that message would have come across.
I don't think I have ever tried to discourage anyone here from trying new ideas.
I said it was rude to ignore or disregard advice after asking for help
As a scientist I am all for experimentation. If you have read my posts hopefully that message would have come across.
I don't think I have ever tried to discourage anyone here from trying new ideas.
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No, you have not
Always been helpful
And maybe learned something as well
Just a memory
Do someone else but me remember a long time ago when Nelson supported a couple of young lads trying to use a gainclone thing as a driver stage fore ZEN amp
Or something like that
It was quite impressive to follow
It was going on intensively quite a while
Young lads who were eager to learn
But also seemed to learn fast
I believe one was chinese or korean
That was my first time reading this forum
I knew right away it was something special
A long time ago now, and many other things have happened
I do wonder tho
The connex guys design amps with a gainclone thing as driver
Im not sure that a common thing, is it
Just a crazy thought
Hi Patrick,
I'm sure, your choice for the resistor values improve the thinks here. But during the building of my F5 I decided to use in a first step the original values and to switch to your values (or maybe new values) at a later time. This, because I wasn't sure where I would end up: your X proposal, a simple (not grounded) connection between the JFET source resistors or four single F5s. Now, some month later I must say I was quite lazy. I spent all my free time listening to this wunderful amp and a lot of money for buying new CDs.
Cheers, Uwe
BTW, have you published your preamp design somewhere here on diyAudio? Or maybe elsewhere?
I hadn't any problems with increased DC offset drift (neither absolute nor differential) beside the well known absolute offset drift after power on (during heating). Right now the absolute offset is something around 10mV and the differential offset is around 1mV for both channels.
For a first rough bias and offset adjustment I have shorted the X and connected this node to GND. After setting the bias for every board I removed the short and all the following fine adjustments were done in the final X configuration without any problems. Of course the bias and DC offset adjustment for the Xed F5 is more time-consuming then for the original one.
Regards, Uwe
Yes, I used the amp in this configuration three month or so without any issues. But keep in mind that the Xed F5 isn't a perfect single to balanced converter, i.e. the amplitude at the inverting output is lower then at the noninverting output. You get the best even distortion cancellation results only with a balanced input signal.
Regards, Uwe
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