Author Topic: Discrete TubeLess...  (Read 43792 times)

gez

Re: Discrete TubeLess...
« Reply #80 on: October 14, 2007, 03:52:56 AM »
I think we should call the 'new' technology CFET, or possibly CJET (complementary JFET).  Unless anyone has a better name?  :icon_razz:
'new'?
http://www.geofex.com/Article_Folders/foolwfets/foolwfets.htm

You'll note that I put the new in inverted commas, John, thereby acknowledging that it's not new.  That aside, the circuit I've devised is 'new' in that the biasing is closer to that used in CMOS inverter circuits.  Whether this is responsible for the soft clipping, I don't know: perhaps I've wasted my time reinventing the wheel (hadn't seen RG's article before).  I'll breadboard his circuit to make a comparison and report back.
« Last Edit: October 14, 2007, 04:15:50 AM by gez »
"They always say there's nothing new under the sun.  I think that that's a big copout..."  Wayne Shorter

gez

Re: Discrete TubeLess...
« Reply #81 on: October 14, 2007, 06:37:58 AM »
That aside, the circuit I've devised is 'new' in that the biasing is closer to that used in CMOS inverter circuits.  Whether this is responsible for the soft clipping, I don't know: perhaps I've wasted my time reinventing the wheel (hadn't seen RG's article before).  I'll breadboard his circuit to make a comparison and report back.

Well, it seems that I have indeed been reinventing the wheel!  RG's circuit exhibits the same soft-clipping characteristics as the one I devised (I used a bypass cap for the p-channel's source resistor in my own circuit and left it in, incidentally).  Although there are some advantages to having a feedback network, in the majority of case I'd find it hard to justify the 3 extra components it takes to do this, so well done RG, and thank you John for drawing my attention to his design.
"They always say there's nothing new under the sun.  I think that that's a big copout..."  Wayne Shorter

WGTP

Re: Discrete TubeLess...
« Reply #82 on: October 14, 2007, 02:29:31 PM »
I guess I kinda have a mosfet thing going.  The SansValve after the Dist+ without diodes has a really nice "character" to it.  It's pretty crispy/crunchy, but has nice fat lows as well.  Seems to have lots of compression.  I removed the 1K and 100 ohm resistors to no effect, but the parts count is getting lower.  Need to try the mods suggested.   I have been using this set up with a single Mosfet Boost in place of the SansValve.  I'll have to compare after futher tweaking.  Thanks again for the new (to me) circuit.  :icon_cool:
Stomping Out Sparks & Flames

puretube

Re: Discrete TubeLess...
« Reply #83 on: October 15, 2007, 12:31:20 PM »
arrgh - those JoyFets seem to be those devices that seem to vary in pinout from manufacturer to manufacturer...  :icon_evil:

puretube

Re: Discrete TubeLess...
« Reply #84 on: October 16, 2007, 05:02:19 PM »
GEZ: thanks for all your information, comments, feedback and inspirations!

I got it!  :icon_wink:

(in fact it was worth reading/studying paperwork for 3 days on end without finding anything like it...).

The "Starving Pinch Bridge" ...  :icon_razz: :icon_razz: :icon_razz:

gez

Re: Discrete TubeLess...
« Reply #85 on: October 16, 2007, 05:08:59 PM »
Ton, not sure what exactly it is that you've got, but I'll defend your right to have it to the death!  :icon_razz:  :icon_lol:
"They always say there's nothing new under the sun.  I think that that's a big copout..."  Wayne Shorter

puretube

Re: Discrete TubeLess...
« Reply #86 on: October 16, 2007, 06:46:02 PM »
My rights are Your rights, Sir!

will send you the schemo tomorrow.

3 discrete components, basically - no trimming - 0.5A @ 9V - instant simulated entubification guaranteed...

(the component values are NO typo!)


(goes under the workname: "puretube`s egg")  :icon_mrgreen:


[EDIT]: one active solidstate device...
« Last Edit: October 16, 2007, 06:48:08 PM by puretube »

gez

Re: Discrete TubeLess...
« Reply #87 on: October 17, 2007, 08:50:38 AM »
3 discrete components, basically - no trimming - 0.5A @ 9V - instant simulated entubification guaranteed...

(the component values are NO typo!)

Well, if the extra parts are for a servo/auto-bias then I almost beat you in terms of component count.  Unfortunately, though, I couldn't stop the circuit from oscillating once AC was decoupled.  However, it just occurred to me that if I plumb the signal in via the servo circuit instead of to the gates of the FETs, then it just might work...doubt it, but one can dream!  :icon_lol:
"They always say there's nothing new under the sun.  I think that that's a big copout..."  Wayne Shorter

puretube

Re: Discrete TubeLess...
« Reply #88 on: October 17, 2007, 09:14:10 AM »
those named 3 components of course do include input and output coupling caps...  :icon_wink:  :icon_smile:

brett

Re: Discrete TubeLess...
« Reply #89 on: October 17, 2007, 08:57:01 PM »
Quote
arrgh - those JoyFets seem to be those devices that seem to vary in pinout from manufacturer to manufacturer... 
J201 and MPF102. With those devices, I've nly seen one pinout, which is shared by both (DSG).  They give you have access to almost the whole signal JFET universe.
IIRC, there might be a slightly less common Vgs-on range around 3 V, because J201s are mostly higher (less neagative) and MPF102 mostly lower.
cheers
Brett Robinson
Let a hundred flowers bloom, let a hundred schools of thought contend. (Mao Zedong)

gez

Re: Discrete TubeLess...
« Reply #90 on: October 20, 2007, 09:28:51 AM »
The reason seems to be the softer clipping: even when driving the JFETs (one n-channel, one p-channel) hard so that the sides square up, the corners are always rounded so there's less hi-end fizz than CMOS circuits.

It seems that the opposite is true.  Onset of clipping is soft, but the output is easily pushed into hard-clipping if the input signal gets 'frisky'.  Although this expands the dynamic range somewhat, it doesn't sound very convincing with one stage.  Might sound better with 2 stages.  Will have to experiment some more...
"They always say there's nothing new under the sun.  I think that that's a big copout..."  Wayne Shorter

puretube

JoyFet
« Reply #91 on: October 22, 2007, 06:03:44 PM »
"JoyFets" soon to be continued in another non-mos thread...  :icon_wink:

puretube

Re: Discrete TubeLess...
« Reply #92 on: October 24, 2007, 12:41:09 PM »
Quote
arrgh - those JoyFets seem to be those devices that seem to vary in pinout from manufacturer to manufacturer... 
J201 and MPF102. With those devices, I've nly seen one pinout, which is shared by both (DSG).  They give you have access to almost the whole signal JFET universe.
IIRC, there might be a slightly less common Vgs-on range around 3 V, because J201s are mostly higher (less neagative) and MPF102 mostly lower.
cheers

gotta love the "pinout" of this Motorola device...
(or here)

 :icon_rolleyes:

dschwartz

Re: Discrete TubeLess...
« Reply #93 on: October 24, 2007, 01:53:36 PM »
yikes!

maybe its a new kind of transistor..the GERMOSBJFET TRIODEY
----------------------------------------------------------
Tubes are overrated!!

http://www.simplifieramp.com

~arph

Re: Discrete TubeLess...
« Reply #94 on: October 25, 2007, 07:21:57 AM »
Hahaha probably some frustrated motorola employee who didn't get his raise.

WGTP

Re: Discrete TubeLess...
« Reply #95 on: October 27, 2007, 03:42:35 PM »
« Last Edit: October 27, 2007, 03:45:32 PM by WGTP »
Stomping Out Sparks & Flames

petemoore

Re: Discrete TubeLess...
« Reply #96 on: October 28, 2007, 02:43:06 AM »
  Very cool..hafta try this one.
Convention creates following, following creates convention.

grolschie

Re: Discrete TubeLess...
« Reply #97 on: May 20, 2008, 01:25:58 AM »
Anyone tried these? Sound samples? Thanks in advance.  :)
grol

gez

Re: Discrete TubeLess...
« Reply #98 on: May 20, 2008, 03:09:07 AM »
I think we should call the 'new' technology CFET, or possibly CJET (complementary JFET).  Unless anyone has a better name?  :icon_razz:
'new'?
http://www.geofex.com/Article_Folders/foolwfets/foolwfets.htm

You'll note that I put the new in inverted commas, John, thereby acknowledging that it's not new.  That aside, the circuit I've devised is 'new' in that the biasing is closer to that used in CMOS inverter circuits.  Whether this is responsible for the soft clipping, I don't know: perhaps I've wasted my time reinventing the wheel (hadn't seen RG's article before).  I'll breadboard his circuit to make a comparison and report back.

Seeing as this thread was revived, might as well give an update. 

Although RG's biasing was simpler, I reverted back to my original idea using feedback as part of the biasing.  Controlling closed-loop gain enabled me to contain things within the soft clipping zone.  Without it, there's a fine line before the amp is pushed into hard clipping (very unmusical as there's no gradual onset).  For a workable design a multistage circuit is required, plus a scope and signal generator.

Didn't build a circuit.  Unless CMOS chips go the way of the dodo, I'll stick with them as less work is required.
« Last Edit: May 20, 2008, 03:11:04 AM by gez »
"They always say there's nothing new under the sun.  I think that that's a big copout..."  Wayne Shorter

TELEFUNKON

Re: Discrete TubeLess...
« Reply #99 on: May 20, 2008, 03:10:30 AM »
Petri: I had posted some nice basic FET links in an old thread,
(see also reply#24, there)
which I had deleted a while later after having been annoyed/molested by the usual gang, for whom I thought
it wasn`t worth pointing to at that time...

I dug them out again for explanations in some other recent threads.

they`re interesting, but don`t reveal all questions:
FET principles & circuits pt.1,
pt.2,
pt.3,
pt.4, by the great Ray Marston.

Those N&V links don`t seem to work anymore
but excerpts are found here: http://www.uoguelph.ca/~antoon/tutorial/xtor/xtor10/xtor10.html
« Last Edit: May 20, 2008, 03:12:40 AM by TELEFUNKON »