Shakti Overdrive

[Kipper4]

Credit to Aron and Jack for the Shaka OD
Heres some plageurised ideas I've thrown together with a view to breadboarding it.
I figured put the EQ first for pre emphasis. I haven't done this before.
If you see a potential problem point me in the right direction please.
Thanks for looking
Rich

[slacker]

Looks interesting, I've never tried EQ before clipping either so look forward to hearing what it sounds like.
It needs an input cap, otherwise DC can get to the input from the output of the first opamp though the resistors and bass pot, apart from that it looks good to me.
You might want a buffer in front of it, the input impedance is quite low and varies with different settings of the tone controls, might be fine though but performance will be different with guitar straight in compared with if it's after a buffered pedal.

[blackieNYC]

EQ first is always wonderful. What are your corner freqs? Will this EQ's mids remain unaffected, like a mid hump or mid dip can be achieved?
And since I miss my butchered MXR D+ (it's now an F) this looks like an excellent replacement.

[Kipper4]

Thanks Ian. I wondered if it might need an input cap. I didn't see that direct DC path to input, so I might put a 100nf>1k series input. Just for safegaurding.

I haven't done any calcs Blackie. I just pinched the active eq from the boss fa1 which I'm fond of.
Plus I'm not sure how it going to react with the gain/clipping. Which is from the Shaka5.
If needs be I'll stick a jfet buffer up front too.

I'm gonna put it on the BB now.
I'm having a few days rest from the discreet compressor to clear my mind and return with a fresh perspective and ears.

Cheers
Rich

[Kipper4]

Spot on Ian. it's loading. I'm gonna need a buffer.
The eq works on the BB now, Gain stage next.

[Kipper4]

Ver 2 some changes from previous

[Kipper4]

[Groovenut]

Rich,

I recommend running R4 to VB instead of ground, you'll get better headroom. 

[Kipper4]

Thanks mate I'll give it a go.

[Kipper4]

As it happens I didnt include R4 on the breadboard.
It doesnt make a lot of difference to the sound either.
voltages to follow.

heres a screenshot of the tone stack approximation Blackie

[Kipper4]

Q1
d=9v
g=0v03
S=1v45

op amp is tl072
1=4v5
2=4v5
3=4v3
4=0
5=4v1
6=4v5
7=4v5
8=9v

I swapped out the bat41 diodes for 1N4148s

[Kipper4]

Question for those in the know.
I've been futzing with the clipping arrangement of the drive.
This is an arrangement I like (see image)
Question is what did I do.
Have i simply bypassed one of the clippers?
something else?
What?
Thanks guys
Rich



the bigger picture

http://i.imgur.com/uJaoXZZ.png

just in case its not clear the switch goes to either source or gate of the mosfet

[aron]

You have a cool looking MXR distortion with pre EQ. How does it sound with different amps? I wonder if it could use a final tone control?

[Kipper4]

Whoop Whoop Go me.
I reinvented the mxr 250.

More Eq. Why not?
That makes 5 knobs 1 switch total, If I can keep the post Eq to a single pot.
Suggestions for the EQ welcome.

It has a lot of different sounds depending on playing style.

My tube amp has a bad hum issue right now So I'm avoiding using it.
I tried pushing the tubes in a bit but it didnt improve it.
I have a feeling its the mains power supply because the solid state amp has it too but much smaller. Thats a seperate issue anyway. (if anyones intrested in helping I'll start a thread in the lounge)

I really like the mild overdrive sound it does at certain settings.
The pre Eq is great too.

[aron]

You can use any tone control from the Rat to the crunch box. They will all work with this type of circuit.

[PRR]

> the switch goes to either source or gate of the mosfet

Looks to me that, either way, Q3 does nothing (wasted dime) and is susceptible to static ZAP.

[Kipper4]

Thanks Paul
I'll change that then.

[Kipper4]

Errata
there is a missing connection.
The C10 C11 and R10 are all connected to Bass lug 2

I put a RC filter just before the output too.

series 100k pot 2n2 cap to ground.
      I --I
----\/\/\/\/\------------------        to OUTPUT CAP
       b100K      I
                     I
                    --
                    -- 2NF2
                     I
                    \/