Profusion in the UK does sell audio grade mosfets.
They have a 2sk1058 substitute. Also have versions that are more closely matched.
Red or green dot, can't rember which...
Built a stimulated F7 with them. Worked fine.
They have a 2sk1058 substitute. Also have versions that are more closely matched.
Red or green dot, can't rember which...
Built a stimulated F7 with them. Worked fine.
I have been asked various questions about alternative devices for the J2.
If anyone, Nelson who designed the circuit should be the one to answer those questions, not me.
I just mess around for my own interest.
The sonic signature of the J2 circuit is largely determined by the front end diff pair and the bottom power device.
If you replace those by something else, you will change the character and should not call it J2 anymore.
The modulated current source at the top rail has less influence and one can consider alternatives there.
I have already explained why I prefer 2SK3497, but that is my prejudice for Japanese FETs.
Nelson has mentioned IRFP240, others IRFP150 or IRFP250.
They will all work, but you might need to adjust the power resistor values at the output to adjust the level of current modulation.
The values shown in the 3497 schematics are default values which gives equal dynamic current sharing between the Semisouth and the Toshiba.
Individual FETs with different transconductances will change the picture somewhat.
That is the only reason why you want to use matched pairs for stereo, so that the 2 channels are identical.
Can you use one of those MOSFETs to replace the Semisouth, functionally ?
The simple answer is no.
The complex answer is yes, if you know what you are doing.
All these high Yfs MOSFETs have large positive tempco, where Semisouth has close to zero.
Also the Vgs at bias is hugely different.
So you need to change the darin resistor value, and maybe use a NTC in parallel.
The J2 is a costly project.
If you are not experienced in DIY and do not understand circuits, then my advice is DO NOT attempt this.
Any circuits that look simple have hidden complications that can make things go wrong.
It is unfair to rely on anyone here to carry you along and solve your problems.
Try something suitable for beginners first, like Nelson's excellent ZEN series amps.
You have been warned.
Patrick
If anyone, Nelson who designed the circuit should be the one to answer those questions, not me.
I just mess around for my own interest.
The sonic signature of the J2 circuit is largely determined by the front end diff pair and the bottom power device.
If you replace those by something else, you will change the character and should not call it J2 anymore.
The modulated current source at the top rail has less influence and one can consider alternatives there.
I have already explained why I prefer 2SK3497, but that is my prejudice for Japanese FETs.
Nelson has mentioned IRFP240, others IRFP150 or IRFP250.
They will all work, but you might need to adjust the power resistor values at the output to adjust the level of current modulation.
The values shown in the 3497 schematics are default values which gives equal dynamic current sharing between the Semisouth and the Toshiba.
Individual FETs with different transconductances will change the picture somewhat.
That is the only reason why you want to use matched pairs for stereo, so that the 2 channels are identical.
Can you use one of those MOSFETs to replace the Semisouth, functionally ?
The simple answer is no.
The complex answer is yes, if you know what you are doing.
All these high Yfs MOSFETs have large positive tempco, where Semisouth has close to zero.
Also the Vgs at bias is hugely different.
So you need to change the darin resistor value, and maybe use a NTC in parallel.
The J2 is a costly project.
If you are not experienced in DIY and do not understand circuits, then my advice is DO NOT attempt this.
Any circuits that look simple have hidden complications that can make things go wrong.
It is unfair to rely on anyone here to carry you along and solve your problems.
Try something suitable for beginners first, like Nelson's excellent ZEN series amps.
You have been warned.
Patrick
I was just re-reading post #1281 FirstWatt J2
Would you be able to describe the sonic difference with the mirror please, I assume it has a different character to paralleling the LTP.
Would you be able to describe the sonic difference with the mirror please, I assume it has a different character to paralleling the LTP.
You are generalising things out of context.
One of the key reasons for using a current mirror in the EB602 is the lack of gain (Yfs) of the lateral FETs.
To make up for this, you have to increase the gain of the input stage by putting a high impedance dynamic load at the drain.
i.e. the current mirror.
When you have sufficient gain with a high Yfs device, a current mirror might get you so much open loop gain that you run into stability problems.
And in general Borbely designs use a lot more NFB than Pass, or Curl.
So horses for courses.
Patrick
One of the key reasons for using a current mirror in the EB602 is the lack of gain (Yfs) of the lateral FETs.
To make up for this, you have to increase the gain of the input stage by putting a high impedance dynamic load at the drain.
i.e. the current mirror.
When you have sufficient gain with a high Yfs device, a current mirror might get you so much open loop gain that you run into stability problems.
And in general Borbely designs use a lot more NFB than Pass, or Curl.
So horses for courses.
Patrick
Thank you Patrick, learning all the time, I know both methods increase open loop gain, I should have looked at post #1266 for the reason.
This thread is about original FirstWatt J2 amplifier or not?
If yes, please open a new thread and change the name to inspired or something similar to J2....
but not FirstWatt J2 still in production........
Oh FW design chassis copy made in China without permission and the PCBs who fits inside its not a shame but kudos ??
Greedy Boyz Ok, but I am not in Illusion Boys team.. not my sorry folks.
?
If yes, please open a new thread and change the name to inspired or something similar to J2....
but not FirstWatt J2 still in production........
Oh FW design chassis copy made in China without permission and the PCBs who fits inside its not a shame but kudos ??
Greedy Boyz Ok, but I am not in Illusion Boys team.. not my sorry folks.
?
I did mention Kudos
it is , in specific cases ....... you know - Greedy Boyz are Greedy , by definition
that's same as cookies and icecream , when we were Kids
so , one can say no-no , with education on mind , but smiling inside
same as you would buy WE 300B for good price , even if Devil himself is merchant
it is , in specific cases ....... you know - Greedy Boyz are Greedy , by definition
that's same as cookies and icecream , when we were Kids
so , one can say no-no , with education on mind , but smiling inside
same as you would buy WE 300B for good price , even if Devil himself is merchant
With Nelson's approval :
https://www.diyaudio.com/forums/pass-labs/151909-firstwatt-j2-26.html#post5892862
(post #1271)
https://www.diyaudio.com/forums/pass-labs/151909-firstwatt-j2-28.html#post5899908
(post #1368)
https://www.diyaudio.com/forums/pass-labs/151909-firstwatt-j2-27.html#post5895873
(post #1326)
Cheers,
Patrick
I like to build stuff, and I'm a particular fan of Nelson's designs (both aurally and aesthetically).
I also like to share and have contributed my board designs to several Group Buys. (Nelson himself donated the Lovoltechs to go with one of them, which strikes me as an odd way to show displeasure.)
What I'm not much into is telling other people how to enjoy the hobby of DIY.
Cheers,
Jeff.
I also like to share and have contributed my board designs to several Group Buys. (Nelson himself donated the Lovoltechs to go with one of them, which strikes me as an odd way to show displeasure.)
What I'm not much into is telling other people how to enjoy the hobby of DIY.
Cheers,
Jeff.
My hope You mean Your similar version to J2?
Not the same amplifier clearly but with the same FW name TM ?
Strange way of thinking..
Best regards 🙂
> Not the same amplifier clearly but with the same FW name TM ?
https://www.diyaudio.com/forums/pass-labs/151909-firstwatt-j2-26.html#post5892475
(post #1258)
"So here you are.
It is not the original.
If that is what you want, I am sure Nelson will be happy to sell you one.
But what is proposed here would be fun to build without breaking the bank."
I cannot find any of my posted schematics or PCB layout using the name "First Watt" or "Nelson Pass".
Maybe you can ?
Post #1271 (22 August 2019):
Nelson wrote "EUVL's schematics above look fine to me if you want to build a J2.
And if you want to DIY your own, be my guest."
The PCB Gerber files are here in the public domain, and clearly labelled as J2 Clone.
I asked Nelson for his approval before posting. He had no objections.
Maybe you have ?
Cheers,
Patrick
https://www.diyaudio.com/forums/pass-labs/151909-firstwatt-j2-26.html#post5892475
(post #1258)
"So here you are.
It is not the original.
If that is what you want, I am sure Nelson will be happy to sell you one.
But what is proposed here would be fun to build without breaking the bank."
I cannot find any of my posted schematics or PCB layout using the name "First Watt" or "Nelson Pass".
Maybe you can ?
Post #1271 (22 August 2019):
Nelson wrote "EUVL's schematics above look fine to me if you want to build a J2.
And if you want to DIY your own, be my guest."
The PCB Gerber files are here in the public domain, and clearly labelled as J2 Clone.
I asked Nelson for his approval before posting. He had no objections.
Maybe you have ?
Cheers,
Patrick
I ..same as you would buy WE 300B for good price , even if Devil himself is merchant
I do have confidence in official components distributeurs : Mouser , Radio Spares, Conrad or Western Electric if for 300B tubes.
Non need to ask imaginary merchants.
Anyways name Babelfish versions and his own thread are clearly not pretend to be original.
Kudos 🙂
Enjoy DIY spirit hobby or clone design of commercial J2 products ?
You share boards with dimensions who are made specialy for business of fake FW chassis and make Group Buys....
pcb´s and chassis are ready made by machines in China not Mr. JeffYoung passionate DIYer
hands work for him self one amplifier piece..that is the truth.
Look on ebay for the Semisouth device, heaps listed out of China - absolutely not one would be the real thing. Fakes and counterfeits every where!!!
Buyer beware.
Buyer beware.
I recon your concern like previous case where you were banned because of criticism to a clone of DIYstore board (i forgot whice board maybe AJ) by someone who was considered as 'forum treasure'Enjoy DIY spirit hobby or clone design of commercial J2 products ?
You share boards with dimensions who are made specialy for business of fake FW chassis and make Group Buys....
pcb´s and chassis are ready made by machines in China not Mr. JeffYoung passionate DIYer
hands work for him self one amplifier piece..that is the truth.
I know Papa is a kind enough not saying 'do not clone my production product guys' but we should know it that this is not proper act
build a separate thread, name it to whatever you like, no issue saying 'inspired by J2', that is more proper
