Starting schematic for a distortion

[Gus]

http://www.aronnelson.com/gallery/main.php/v/gus/

Click on plus and then click again.

Circuit fragment with a buffered adjustable high pass and a X2 make up output driver with about a 10K max output resistance(think TS to triode in R.G. writeup)  after the distortion section for things like GE shunt clippers.  One could take a D+ type circuit and move the high pass with gain to the input and make the cap in the gain leg a larger electrolytic.

Vref can be a resistor string or a buffered Vref using an opamp so maybe two duals.

One can use a DPDT and a led if you switch at the output of the input buffer.

Have fun

[Gus]

No replys with all the Dist + threads at this site.

Does anyone that looked at the schematic understand what I drew?

Buffer with a 470K input resistance or you can make it 1 meg or...

Drawn is a kind of d+ in the middle but the EQ with gain can be removed with a bigger cap on in the gain leg pot and resistor the middle can be other type distortions a rat type or....

The buffer allows a pot to be used to adjust the high pass frequency it might make noise but it might be a set and forget type trim think RM input meets the D+

Now some want more output level when using one Ge per side of a shunt clipper distortion and adding more doides changes the sound so a boost of X 2 should be a good starting point

The output having a X2 opamp circuit can drive 10K look close at R.G.'s TS write up about the output buffer

you need to click two times and might have to resize it to fit your screen

[John Lyons]

Gus
Yes, that looks interesting. The high pass before the D+ is an interesting idea for boosting a dark amp or to cut through pedal chain.
The lower imp output is nice as well.

John

[ConanB]

I've been wanting to take a look at alot of different distortions to try and help myself in understanding how circuits work and this will help alot in figuring out the stages of a pedal, so cheers!

[slacker]

Nice. The highpass in front of the disortion stage is a great idea, much more elegant than messing around with the cap and resistor combo off the inverting input to vary the bass response.
The output booster is very useful in my opinion. I don't know why more pedals don't include it, especially ones that use the second half of the opamp as a buffer after the distortion stage, that always seems like a waste to me.
I bet this basic layout would work great with a discrete opamp for the disortion stage. You'd have all the advantages offered by the TL072 stages and all the tonal goodness of the discrete opamp.

[DougH]

The highpass in front of the disortion stage is a great idea, much more elegant than messing around with the cap and resistor combo off the inverting input to vary the bass response.

Two things to consider there: It depends on the shape of the curve you want. A high pass filter in the op amp feedback set up has a different frequency response curve than a passive high pass filter as shown here.

If you do implement a variable high-pass filter via a variable resistor in the inv leg of an op amp circuit, it will affect gain too. It could be useful to increase Fc of a HPF while increasing gain (like Red Snapper, Gainster, or even Gus's NPN Boost - which essentially does that by lowering Zin). But you may not want that and the nice thing about Gus's scenario here is that it decouples the variable high pass filter control from affecting the gain.

[R.G.]

Does anyone that looked at the schematic understand what I drew?

Some, but not nearly all. As more and more people with no electronics background come here, the fraction of members who can understand design issues goes down.

[ConanB]

Does anyone that looked at the schematic understand what I drew?

Some, but not nearly all. As more and more people with no electronics background come here, the fraction of members who can understand design issues goes down.

Some of us are trying though
I come from a coding background and always try to know exactly whats going on "inside the box", be it a game console box or a FX box.

I'm sure other fresh faces are doing the same thing.

[WGTP]

I think your talking about me!  Isn't changing batteries in a flash light enough electronics background?  Remember your audiance is a bunch of guitar and bass players, we are doing well just to find this place and log on.  

This might help me figure out what's going on with the input side of a DS-1 with the buffer and BMP stage prior to the op amp buffer and distortion/gain stage.  

Over the last few years, I have found Gus' stuff to be the ones I am most likely to miss the subtley elegant complexities and later have "aha" moments about.  Of course that is still happening with all of this stuff.  I'll have to look this one over for a while, you guys keep explaining it for us, please.  Thanks again for you patients.  

[Gus]

Using opamps as buffers is not a new idea in effects

Separating the high pass can be good or bad depends if you want a shelf(TS, D+ gain of 1 then highpass) or "truer" highpass (RM INPUT) or a combination of both.  For live players it can be very good IMO, effects that work at home can maybe not work so well on stage with open back speaker at loud volumes.   

I have left hints like the thin/ thick switch. 

I also don't understand why people keep using >10K audio volume pots at the end of circuits with opamps.  At 9V almost any opamp should be able to drive a 10K load.  This gives less series R into say a tube preamp.  And as R.G. has written about lower output R in the mil bypass stuff it can reduce popping because it "Drains" the output cap better(rat section IIRC).

The fragment is nothing special BUT I hope it gets people thinking about why this or that in circuits

[Gus]

double post

[WGTP]

http://www.aronnelson.com/gallery/main.php/v/WGTP/Gus.JPG.html?g2_imageViewsIndex=1

I redrew this and tried to fill in the blanks.  Gus if you want to copy into your stuff, I'll delete it from mine.

A continuation of my DS-1 study.  It has an input buffer the BMP stage (I'm sure there is a proper name for it) the op amp buffer, then distortion stage, clippers, BMP "like" tone control, output volume control and output buffer.  It appears this would filter would fit in there somewhere. 

Let me know if I need to fix anything.  Thanks again.   

[R.G.]

Does anyone that looked at the schematic understand what I drew?

Some, but not nearly all. As more and more people with no electronics background come here, the fraction of members who can understand design issues goes down.

Some of us are trying though
I come from a coding background and always try to know exactly whats going on "inside the box", be it a game console box or a FX box.

I'm sure other fresh faces are doing the same thing.

I think your talking about me!

Even as I wrote that, I was sure that it would hit a number of people like that. A lot of people - in raw numbers - do push hard to understand, and those are the ones who unfortunately would feel like 'hey, wait a minute...' as a result of that remark.  If you felt that way, be proud. You may be the one who comes up with the next killer effect.

Not everyone has either the ability and motivation to do this at a deeper level than etching a PCB and drilling a box. That's fine, and no shame attaches to that. I'll never hit a hole in one, never run a four minute mile, and never get any salesman of the month awards. Egad, this is turning into Ecclesiastes - to every thing there is a time, and  purpose to everything under heaven. Agh.

[Gus]

You might want use 2 duals and have 1/2 of one as a buffered ref.  Also the input and output noninverting opamp sections should be fet inputs IMO.

What I drew is a starting point and I am not posting this is best etc, the resistor values are starting points and the cap in the highpass can be picked with f=1/(2piRC) set the pot to 0 and then full and do the calculations for the range YOU want it to work in.

  The main ideas

the buffer and then adjustable high pass

Distortion section of you own choosing

A buffer or a gain stage after the distortion that drives a 10K volume pot or one can use a volume pot before the output buffer and have even a lower output resistance opamp section.
The gain is to help out shunt clipper type distortions.

You can also show a DPDT switch using 1/2 of it to switch  the outputs after the input buffer and use the other 1/2 to switch a led don't need a 3pdt if you don't mind the input buffer.

I drew the fragment after reading all the D+ threads over the years and wondering when people were going to make the next step and change the D+ type circuits a bit.

[johngreene]

http://www.aronnelson.com/gallery/main.php/v/WGTP/Gus.JPG.html?g2_imageViewsIndex=1

I redrew this and tried to fill in the blanks.  Gus if you want to copy into your stuff, I'll delete it from mine.

A continuation of my DS-1 study.  It has an input buffer the BMP stage (I'm sure there is a proper name for it) the op amp buffer, then distortion stage, clippers, BMP "like" tone control, output volume control and output buffer.  It appears this would filter would fit in there somewhere. 

Let me know if I need to fix anything.  Thanks again.   

Since there are 3 opamps it is begging for a quad opamp (or 2 duals) package with the 4th opamp being used for the 4.5V supply....

[WGTP]

Hey, I fit the description.    I have been avoiding learning real electronics for 40 years now.  I could figure out how op amps really work, or I could play my guitar, change pickups, write a song, play pool, cruise, etc.  The math isn't a problem, I had 12 hours of calculus in college.  It just isn't nearly as interesting to me as the many other things related to music and tone.  Creating a great tone is interesting, but I guess not enough to figure out the boring, at least to me, details.  Changing caps and diodes or a different tone control is way cooler.  I forced myself to figure out bread boarding and haven't built a box since.  I have just learned enough of this stuff to manipulate the sound part of it.  I also need to work on my stage presence.   

As Gus said, the Distortion+ has plenty of room for improvement, but I think folks like the simple primitive and easy to understand aspects of it.  The Rats, DS-1, Expandora, etc. are advancements, and they quickly turn into Rocket Science to me.  That's why I'm still figuring out the different parts.

To you guys that have the discipline to learn the electronics, I tip my hat.  Keep helping the rest of us with the electronics and maybe we can help you with your cloths and hair.  Deal?  Thanks again.   

[WGTP]

http://www.aronnelson.com/gallery/main.php/v/WGTP/Gus.GIF.html

Revised and changed link.