Jfet preamp secret

There are no secrets really, just basics. JFets has properties which are similar to tubes and they have a different kind of distortion compared to ordinary BJT's.

Why don't you check Erno Borbelys designs for inspiration.
http://www.borbelyaudio.com/

http://www.ne.jp/asahi/evo/amp/

http://www.f8.dion.ne.jp/~isiatama/kaiseki/kaiseki_index.htm

If you can read japanese

http://babelfish.altavista.com/urlt...ion.ne.jp/~isiatama/kaiseki/kaiseki_index.htm

I have lot's of old application books with JFets theory, unfortunately not availible on the net.
 

leiade

Disabled Account
2002-09-14 9:46 pm
Jfet

Oh yeah ! I have seen the old eastern designs and even built a few, but no I don't like them I mean something like the JC-2 uppdatet design, modern jfet esoteric high end puh... low impedance loading capablilities with low noise and very low distorsion.
 
The secret is out

Fets sound better.:Popworm:
I have lot's of old application books with JFets theory, unfortuneatly not availible on the net.
:radar:
Contrary to some peoples opinions, there is plenty imformation on the web on jfet theory and applications.

http://www.borbelyaudio.com/ae599bor.pdf

http://www.borbelyaudio.com/ae699bor.pdf

http://www.borbelyaudio.com/borb502.pdf

http://www.forsselltech.com/schematics/Class A JFet Opamp.PDF

http://www.vishay.com/brands/siliconix/SSFan.html

Art

P.S. Don't tell peranders, but simple circuits usually sound better.:shutup:
 

leiade

Disabled Account
2002-09-14 9:46 pm
The Gang of Jfet's

Nice I tried to wake up some sleeping jfet people and I succeeded,
well come on, links and mail to more and reliable jfet constructions extravagant and delicous the ultimate of modern solid state designs with jfet, puh !!.:D
I will soon show what I have done with jfets.

Peranders is a good guy and the circuits he shows seems to use the dirtcheap BC550 and so on, thats good make it cheap and super.

There is a lot of good electronic designers here why can't thoose guys design a super beast preamp, making it as simple and cheap as it is possible.

I don't mean that it would be cheap in choice of components just cheap in total cost do not use a whole bunch of semiconductors.:yes:
 

leiade

Disabled Account
2002-09-14 9:46 pm
Potted in resin

Hi,

I wondered about the "potted in resin modules" (PRM) that some manufacturer sells, why should they care about the potted design if there is no secret about the design.
The first potted resin module I have seen was the ML-1 and now I have seen the Fred Forsell PRM and a german PRM called somthing like "Music Module".

If their construction don't are so exotic and esoteric why should they care about to hide the circuit in a box with epoxy resin as it increase the cost for the product it would hardly make the amplified sound better or... I mean if you use smd components I think that the mechanical vibrations will be reduced to a level that should be enough.:cool:
 
Re: The Gang of Jfet's

leiade said:

There is a lot of good electronic designers here why can't thoose guys design a super beast preamp, making it as simple and cheap as it is possible.

The answer is easy: There is no ultimate solution! You have to choose a direction yourself.

Erno Borberly = JFET, MOSFET

Me = BCxxx, not non-complex

Nelson Pass = Odd, get patents!

Rod Elliott = Easy to build

Evolve = Crazy

the tube guys

and so on...

I gather it's quite impossible to get united in this matter.
 

leiade

Disabled Account
2002-09-14 9:46 pm
The Solution

Dear Sirs,

I'm now leaving this area of preamp design solutions I have got the answers that I really deserved and I also have looked at the obscure japanese jfet designs and they looked very good, better than I first understand.
I also understand that a preamp design should include some other esoteric parts that will affect the whole results.

Maybe we amateurs can set a new standard, an open smd module with a pinout that will fit in a regular high quality socket, if a preamp design will managed this way it would be easy to make different uppgrades very cheap and reliable because the PCB will be much cheapier than an ordinary PCB design.;)
 
Re: why should they care about the potted design if there is no secret about the design.

artnyos said:
I believe it is to keep the design a secret. That way some DYIer won't copy it and save money building his own copy. Of couse,modules can be opened up if one is really curious...... :treasure: :smash: :magnify:

Even more important point, if the buyer looks at the board and see's $ worth of parts they might get ticked about having spent $$$$.

Phil
 
Re: Potted in resin

leiade said:
Hi,

I wondered about the "potted in resin modules" (PRM) that some manufacturer sells, why should they care about the potted design if there is no secret about the design.

If their construction don't are so exotic and esoteric why should they care about to hide the circuit in a box with epoxy resin as it increase the cost for the product it would hardly make the amplified sound better or...


I once potted the preamp module. The reason for it was to achieve thermal stability. The circuit was DC coupled and without potting DC offset was drifting substantially, when potted thou it was very stable. OTOH some people claim that potting is not good for sonics, so I'm kinda reluctant to do it anymore.;)
 

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