little help here

doplonyo · 24th June 2012, 06:33 PM

hi all its me again...

this time I want to be help about eq... in my attachment is tone control using opamps... How to make that circuit work with jfet ??? why I chose jfet because I want solid state with tube taste

I want use it for clean chanel,but if any member want to help me with make me two chanel (overdrive&clean) i'll be more apriciated,and will use it all the time.... all input will be some big help to me...
thanks....

Minion · 24th June 2012, 11:49 PM

It allready uses a Jfet , The TL082 is a Jfet opamp .....

PS:The second half of the TL082 should be configured as an input buffer .....

6L6 · 25th June 2012, 01:29 AM

Try it as shown, it will be a good tone control for an instrument amp.

Loudthud · 25th June 2012, 01:35 AM

Just use a JFET source follower as an input buffer. You need to drive the circuit from a low impedance anyway.

doplonyo · 25th June 2012, 04:23 AM

thanks all ... But I mean I'm try to build that tone with transistor (j201) cos many schematics was using stack tone,in this case I want that circuit build with j201 or similiar,cos I thinks playing with transistor more easier than playing with opamp,what about that???

geraldfryjr · 25th June 2012, 05:52 AM

Actually the opposite is true!!
Opamp's are easier to work with than you lead yourself to believe !!!

I am not good at Jfet amplifiers but if you want to use a one in the circuit you can place a Jfet amplifier in place of the opamp as long as it inverts the signal.
I have no idea how to set or determine the gain of a Jfet amp but if it is not an inverting type amplifier you most likely will have an oscillator.

FWIW

jer

tinitus · 25th June 2012, 08:51 AM

looks like a baxandall feedback control(active)
modded to have 2 bass controls
usually theres only one bass, and one treble
so the question is, will it work properly
or is it a theoretical design ?

hey, Im into trying one myself, and really interested in this

tinitus · 25th June 2012, 09:01 AM

Quote:

Originally Posted by 6L6

Try it as shown, it will be a good tone control for an instrument amp.

actually they say this type of active feedback control is the best kind for hifi as well

its very similar to the tilt control used in Quad preamps
I think it only needs one mutual control to work like a tilt

tinitus · 25th June 2012, 09:04 AM

Quote:

Originally Posted by doplonyo

...... I want that circuit build with j201 or similiar....

will show up on google

by the hundred

I think the type of jfet you use is mostly determined by your voltage
j201 should be good for low voltage like 9V
other jfets may work better on slightly higher voltage
depends on how you plan to use your design
battery or regulated supply, outboard, onboard, built in, etc etc

well, I see the one in your tone control uses symmetric +/- supply
so I guess a low voltage battery supply is not your goal ?

doplonyo · 25th June 2012, 10:52 AM

Some schematic using jfet (j201 or similiar) was 15v to 24v,but using tone stack,then I find that attachment, so I want modify that as I want,any picture or attachment to make easier to build that.... Please.

25th June 2012, 01:29 AM	#3
6L6 diyAudio Member Join Date: Oct 2010 Location: Denver, Colorado	Try it as shown, it will be a good tone control for an instrument amp. __________________ llustrated Build Guides - Pass Pearl 1 - Pass B1 - - Pass F5 - Pearl 2 - -O2 HPA - - Pass F4

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24th June 2012, 11:49 PM	#2
Minion diyAudio Member Join Date: May 2006	It allready uses a Jfet , The TL082 is a Jfet opamp ..... PS:The second half of the TL082 should be configured as an input buffer .....

25th June 2012, 01:35 AM	#4
Loudthud diyAudio Member Join Date: Nov 2007 Location: Near Dallas Texas USA	Just use a JFET source follower as an input buffer. You need to drive the circuit from a low impedance anyway.

25th June 2012, 04:23 AM	#5
doplonyo diyAudio Member Join Date: Apr 2012 Location: Pekalongan Central Java Indonesia	thanks all ... But I mean I'm try to build that tone with transistor (j201) cos many schematics was using stack tone,in this case I want that circuit build with j201 or similiar,cos I thinks playing with transistor more easier than playing with opamp,what about that???

25th June 2012, 05:52 AM	#6
geraldfryjr diyAudio Member Join Date: Feb 2008 Location: Jackson,michigan	Actually the opposite is true!! Opamp's are easier to work with than you lead yourself to believe !!! I am not good at Jfet amplifiers but if you want to use a one in the circuit you can place a Jfet amplifier in place of the opamp as long as it inverts the signal. I have no idea how to set or determine the gain of a Jfet amp but if it is not an inverting type amplifier you most likely will have an oscillator. FWIW jer

25th June 2012, 08:51 AM	#7
tinitus diyAudio Moderator Join Date: Nov 2005	looks like a baxandall feedback control(active) modded to have 2 bass controls usually theres only one bass, and one treble so the question is, will it work properly or is it a theoretical design ? hey, Im into trying one myself, and really interested in this

25th June 2012, 10:52 AM	#10
doplonyo diyAudio Member Join Date: Apr 2012 Location: Pekalongan Central Java Indonesia	Some schematic using jfet (j201 or similiar) was 15v to 24v,but using tone stack,then I find that attachment, so I want modify that as I want,any picture or attachment to make easier to build that.... Please.