Orange OTR Jfet preamp

[fuzzo]

Hi guys,

I'm gonna do a JFET preamp to recycle my MG10 box, and I want to do an orange Overdrive fet preamp with a power suply between 20 and 30V DC (to have a better dynamic). So i did the schematic :



I think the 10k trims will be changed to a fixed resistor .

Do you see mistakes ? errors ?
have you got advices about this project ?


Thanks !

Julien.

[CynicalMan]

If I were you I'd change the High/Low switch to a switch that takes the 1st 47uf cap out of the circuit. I'd just be worried about the 1st JFET stage sucking volume or tone at the low setting.

[guitarman89]

it looks like a jfet emulation of the markII by orange...and...it looks very interested to my project: a dual channel preamp in front of a 60W lm3886 amplifier

[kurtlives]

Looks neat. Your drive control works backwards though.

Looking forward to hearing how this works for you.

[fuzzo]

If I were you I'd change the High/Low switch to a switch that takes the 1st 47uf cap out of the circuit. I'd just be worried about the 1st JFET stage sucking volume or tone at the low setting.

yeah it can be an idea but some input amp is wired like mine, I just copied the design.



yeah it's the same  but mine don't have another  jfet at output to avoid a too gainy preamp.  I'll be a real preamp, not a stompboxe, So I want a dirty clean sound to a big drive sound (not big distortion)



Yeah i know it's like the volume control (always reverse in schematic), I'll wire it in the right way.

So it's seems to be good for you ? So i'll do a veroboard tomorrow and post it here.

Good night !

[kurtlives]

Id definitely breadboard this first before thinking about vero.

[km-r]

hey ive done that before... only with tubes.
it has lots of crunch... but not much distortion.




ohh.... playing through an orange overdrive with a big muff is wicked awesome!

[fuzzo]

http://it has lots of crunch... but not much distortion.

It's a Good thing ! If I need more gain I'll add a boost inside with a switch.



Yeah it's the same idea , a good preamp for rock, hard rock , dirty blues,  stoner rock (zz top , ac/dc , nebula, QOSTA, high on fire, sleep, ect....) and good sound with some fuzzes.

Otherwise, what do you think about the "presence control" at the end ? I've a little doubt if it'll work or not.

[km-r]

the presence will alter the tone but not the way the real amp should... right? theres a feedback there.

i really like those orange amps... im working on a tinyterror + 18watt combination clone now.

[mnordbye]

This sounds interesting! I'll have to breadboard it soon. I do have an orange amp, but i've never gotten myself to try an Orange amp! 

[fuzzo]

the presence will alter the tone but not the way the real amp should... right? theres a feedback there.

In whole amp, it plays on power tube , but I don't know how.

Id definitely breadboard this first before thinking about vero.

I haven't breadboard.

thanks for your answers.

[Derringer]

Is there any way to emulate what the cathodyne PI's add to the Orange sound?

[fuzzo]

So , any another advices ?

Maybe another "presence control" design to have something which alter the global tone ?

Another bias system ? Trimmer at source to don't change the Impedance of the stages.

[km-r]

maybe you could include the cathodyne section in your project. if i think of this, maybe the plate resistance should be equal to the cathode resistance which would make things more difficult when using trimmers...
this section is poor for driving power tubes AFAIK.

as for the power amp section, how about a mu-amp?  idk maybe it'll work.

[Branimir]

Hm...

http://www.diystompboxes.com/smfforum/index.php?topic=71597.0

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