breaded up a son of screamer..however..

[deadastronaut]

Ben,  i have mono ceramics all over, apart from powere rail stuff.....


jim,  ahhh the 220n off  the drive, i got that too...beefs it up...

Is that your version then?

[J0K3RX]

Yeah, it was something that I drew up a while back... not sure if everything is right but the idea is there.

I really want a screamer with one knob (level) and everything else fixed or maybe on 1 or 2 switches. I never touch the drive/gain pot for the way that I use a screamer and the tone really never gets touched either. Drive is usually all the way off or just barely cracked on, tone is usually right in the middle or maybe 3/4 of the way depending on the guitar, amp etc.. Level is the only thing I adjust. Want something like the Fortin Grind pedal with a good mid boost.

[deadastronaut]

Cool, probably best to just use internal trimmers,  nice.

[Ben Lyman]

Okay Rob, cool, thanks. I just noticed you don't show a 1K to 10K(ish) resistor after C9 output cap.
I think I have been lead to understand this extra resistor protects the op amp in some way.

Jim, looks cool. Variable input impedance? Please explain
Thanks!

[deadastronaut]

hi ben, i was just going by this..

http://www.muzique.com/lab/tstone.htm

i ended up going back to the original tone control earlier...seems ok.

ive added ass/sym clipping, and a switch between caps coming off the drive pot..

e.g 47n (original) and 220n..

its a cool drive through my clean channel...very usable..

[anotherjim]

Okay Rob, cool, thanks. I just noticed you don't show a 1K to 10K(ish) resistor after C9 output cap.
I think I have been lead to understand this extra resistor protects the op amp in some way.

Jim, looks cool. Variable input impedance? Please explain
Thanks!

It's so easy to leave out protection resistors in a schematic by accident. It probably won't notice if omitted, but best practice is for the builder to include.
A lot of designs don't show any. Commercial and DIY.

Variable input impedance.
Low impedance makes the guitar signal more fundamental (duller, like treble loss when turning down a pickup facing guitar volume control wiper), so distortion is more harmonics of fundamental, which is good. Some guitars can stand lower impedance than others. Telecaster s/c is quite happy, almost full range about 100k and you can go lower. Humbucker might be too muddy at the same or just perfect for your distortion.
Jim (the other) also put a 220p on his input for a partial tone control rolled back effect.

Not doing much for your if there's a buffer in front, although it will change the high pass of the buffers output cap in the wrong direction if you set the input Z too low. Jim put the variable Z downstream of HIS input cap so the Z change won't change its pass freq'.
.

[deadastronaut]

heres where i am...

i messed around with the feedback value in the output...and its insane..

blasting the opamp to hell...it sustains forever....really really cool..

ben, try it out for a grin ...its sick....i put a 500k pot where R11 is..you end up with
massive ludicrous gain, sustains for days...




nice explanation jim, why do some TS schemos show the gain cap going to VB, and others to ground?

and a 10k to VB after the opamp out  1k? on some too..

[slashandburn]

I'd have got my arse kicked if I brought out the breadboard today, wish I could've got on board with this, looks interesting.

I'd never looked at the Jack Orman tone mods before, I had a read over that page last night, loads to experiment with and try to get my head around. If I remember right I just rashly decided I didn't like the stock tone stage and just dumped it for the BMP tone. 

I'll need to have a look at this soon.

why do some TS schemos show the gain cap going to VB, and others to ground?

and a 10k to VB after the opamp out  1k? on some too..

Wondered this myself. 

[deadastronaut]

yep, tried the standard tone again...and its pants..

i'll try a different one...

[slashandburn]

Yeah i just found its response a bit weird and off-putting.   I wonder if it would make more sense if adapted as two pots as Mark Hammer mentions on another thread.  The last paragraph here:

The fundamental challenge is that the TS tone control tries to accomplish a lot; perhaps too much.  The tone control in the TS is a "reciprocal" control.  So, the one pot adjusts two things at once, and the more it does of one, the less it does of the other.

The first thing it does is increase the gain of the tone stage by reducing the resistance of the ground leg of the tone stage.  As it does that, it not only increases the gain but also alters the low end corner frequency of that stage in exactly the same way as the analogous control does in the MXR Distortion+ (gain goesd and and bass gets cut).

The second thing it does - by virtue of how the control is connected - is gradually add a 2nd .22uf cap in parallel with the one just after the clipping stage.  The 1k/.22uf network after the clipping stage already provides a 6db/oct lowpass filter at 723hz.  Adding the 2nd .22uf cap moves that corner frequency even lower.

So, in complementary fashion, the one control either increases lowpass filtering as it decreases the gain of a potentially treble-boosting stage, OR it minimizes the lowpass filtering as it increases the gain of a potentially treble-boosting stage.  Jack Orman explains this nicely, and offers some alternatives: http://www.muzique.com/lab/tstone.htm

If a person likes what the tone control accomplishes, but wants better control, the simple thing to do is to unyoke those two complementary/reciprocal functions.  So, a person could have a 20k pot and .22uf cap to ground to adjust the lowpass filtering, and a second 20k (or 10k, or 5k) pot in series with a 220R resistor and .22uf cap to ground to adjust the gain of the treble boosting stage.  More complicated, yes, but much better control.

Just throwing that out there as an option. Had me scratching my chin a bit when I read that.

[deadastronaut]

funny, i just read that very article......great minds etc..

[Ben Lyman]

Holy Cow! Just tried the 470k R11, you're right, very nice. I think i detect a slight bottom boost as well, makes it a bit more beefy plus the extra sustain.

My perf is all soldered up and ready for a test before boxing but mine is still closer to an SD-1 than anything. I think what I have now would pair very nicely with what you have here. When I test out my perf I might be able to run it with yours on the BB to see how it works. I love using an OD/boost type thing into an OD/distortion type thing

[thermionix]

Ben, I gotta say, curiousity got the better of me a few days ago, and I googled the word Oozviks.  The only result I got was you, here.  So, what is the reference?

(Sorry for the OT)

[deadastronaut]

ben, ha ha glad you tried it...this is with a 470k and a 2.2n in para...

gets into metal territory...still the same crap tone control...

https://dl.dropboxusercontent.com/u/7464107/WAVES%20FOR%20PELLE/METALSCREAMER1.mp3


signal, guitar, clean amp channel. headphone out to mixer...

[bloxstompboxes]

The question that no one has asked yet is:

How will Rob survive with just a 3 knob circuit? You must add some gyrators within a good tone control or something man!

Sent from my SAMSUNG-SM-G930A using Tapatalk

[J0K3RX]

ben, ha ha glad you tried it...this is with a 470k and a 2.2n in para...

gets into metal territory...still the same crap tone control...

https://dl.dropboxusercontent.com/u/7464107/WAVES%20FOR%20PELLE/METALSCREAMER1.mp3


signal, guitar, clean amp channel. headphone out to mixer...

Damn, that sounds good!!    That headphone out have cab/speaker emulation or something?

Edit: I looked up the schem for the AVT275 and answered my own question.. 

Can you make another sound demo just going direct or going to the fx return on the AVT?

[deadastronaut]

hi jim, not sure on the headphone out...

but i also have L/R emulated outputs too...but i used the headphone out so i can
mess around late at night...


been tweaking, and its pretty damn good...

get it on ya breadboard man...

btw , i swapped the tone pot for a 5k, much better now...

and have a 500kb pot instead of R11...with a 10k resistor off the wiper..

so you have 2 gain pots..so it can be used as a trad TS...or

METAL SCREAMER!!!!

so 4 pots, 2 switches, so far......we need another 28 pages yet..

[deadastronaut]

so it is emulated then?.

anyway, it'll sound nasty i bet just DI'd...as all dirts do.

but i'll give it a whirl...

the idea is to replace the nasty marshall dirt, and i'm quite pleased so far.

[Kipper4]

Smashed it Rob. I guess you're feeling better.
That aint your run of the mill screamer anymore.
Cant wait to see the updated shematic.
I have some space on a breadboard. Lets see if i can turn into a death metal guy.

[deadastronaut]

hi rich, yeah man ....none of that single coil namby pamby bs though...

edit: still a bit sniffly, and coughy, but getting there..whiskey helps