Choob Dreamer - a more flexible Screamer derivative overdrive pedal

[jonny.reckless]

Introducing the Choob Dreamer overdrive. Just what the world needs, another Tube Screamer clone 



This does however have 3 new features:

• A bite control allows voicing of the bass roll off / treble boost
• A symmetry switch adds in a second diode in one polarity
• A presence switch changes the HF roll off from lowpass to shelving

I think these features make it a bit more flexible than just another screamer clone. Nothing here is particularly new or original, but I do think it sounds pretty decent and it is fairly versatile. It's a simple circuit, easy to build, and does not require any special parts or matching of components.





Listen to it here:

Schematic, bill of materials and other photos can be found here:
https://drive.google.com/drive/folders/1vhmmRr2aAVpPaWMJlrmFtE1gEHvQdW0h?usp=sharing

[antonis]

Nice work Jonny..!!
(as usually..)

P.S.
Especially that coarse-fine gain set by RV1/RV4..
(it brings me to mind some old-fashion benchtop power supplies voltage setting..)

[PRR]

> that coarse-fine gain set by RV1/RV4..

Not just a fine trim. (Is your plucker even that accurate?) The 'BITE' resistors provoke different action from C8. Pot short, pole at 3.5kHz, pot full pole at 166.6 Hz. That spans pretty-much the full guitar scale of important overtones. Varying 'DRIVE' does not do that.

[Clint Eastwood]

Just what the world needs, another Tube Screamer clone

I think the world can always use more Jonny Reckless creations. And I love how you present them!

Just one thing: I don't see why you would call it a tube screamer clone. It doesn't have the signature clipping diodes in the feedback path, but rather uses the 'other' clipping method.

[ElectricDruid]

Just one thing: I don't see why you would call it a tube screamer clone. It doesn't have the signature clipping diodes in the feedback path, but rather uses the 'other' clipping method.

Yeah, I was going to mention that too. Given the changed diode position, it's only tenuously a tubescreamer clone. You could say it was the mutant offspring of the DOD-250 and a Tubescreamer?!

Even if the world doesn't need more overdrives, I think we should all keep designing them. It's a fun and interesting challenge!

[niektb]

[...]
You could say it was the mutant offspring of the DOD-250 and a Tubescreamer?!

How about Choob DODreamer?

[jonny.reckless]

Just what the world needs, another Tube Screamer clone

I think the world can always use more Johnny Reckless creations. And I love how you present them!
Just one thing: I don't see why you would call it a tube screamer clone. It doesn't have the signature clipping diodes in the feedback path, but rather uses the 'other' clipping method.

Thanks! Yes I generally prefer the diodes to ground approach, I think it sounds richer, possibly because you get 2 stages of clipping: one with the diodes and one when the opamp clips. And you put much more current through the diodes in this configuration, which I also think helps the sound a bit.

It's not a screamer clone per se but tonally and functionally it's in the screamer / SD-1 overdrive territory, and used for the same purpose. I started thinking about it because I prefer the Screamer when boosting a Fender, and the Boss SD-1 when boosting a Marshall. And sometimes I use an EQ in front of the overdrive for a further treble boost, so I tried to basically roll all those ideas into a simple circuit.

[jonny.reckless]

Nice work Jonny..!!
(as usually..)
P.S.
Especially that coarse-fine gain set by RV1/RV4..
(it brings me to mind some old-fashion benchtop power supplies voltage setting..)

As Paul points out, it's mostly done for different purposes. RV1 sets the broadband gain, whereas RV4 sets the bass turnover frequency. 100n/470R gives you 3.4kHz, 100n/10470R gives you 152Hz, so the bass response "pre gain" is very different. This affects the character of the overdrive quite a lot. Anticlockwise, there is more bass in the signal, which makes the drive more "woody" and "fuzzy". Clockwise, there is much less bass and much more treble in the signal, which makes the drive "biting" and "aggressive" sounding. If you use a C taper potentiometer, in the middle is somewhere around 750Hz which is right where the tube screamer and SD-1 put the corner frequency. I really like a biting overdrive especially with a neck pickup. I often put a treble boost in front of a tube screamer to give it more edge. With the Bite control you can achieve a similar effect.

[bartimaeus]

looks interest, nice hybrid of the DOD and TS as others pointed out! just needs some switchable diodes in the feedback loop (maybe 2+2) to add a bit of Nobels and Barber flavor

if i build this, i might wire a log pot backwards for the "bite" control and call it something else... maybe "voice" like the zendrive 

i do wonder if there's a way to make the bass control more like a timmy, where the gain doesn't vary so much? but without the limited frequency range of the timmy's bass control...

[Ben N]

[...]
You could say it was the mutant offspring of the DOD-250 and a Tubescreamer?!

How about Choob DODreamer?

No transistor buffers, so "Son of Choob DODreamer".

[jonny.reckless]

if i build this, i might wire a log pot backwards for the "bite" control and call it something else... maybe "voice" like the zendrive 

I got the C taper pots from Tayda for $0.50 

[ElectricDruid]

Some of you on this thread would probably be interested in this "Overdrive shootout" that I did - a comparison of the Boss OD-1, Ibanez TS-808, and Boss SD-1. I was surprised by just how close they are. Working out the cutoffs of the various RC combinations shows that some of the value changes between them are changes for change's sake, and don't actually affect the behaviour much / at all.

https://electricdruid.net/wp-content/uploads/2023/02/OverdriveShootout.jpg

NB: I took the FET switching out. No big deal. Most boutique pedals do anyway.

Any comments/errors spotted appreciated by PM, I'm not wanting to hijack the thread.

[jonny.reckless]

Some of you on this thread would probably be interested in this "Overdrive shootout" that I did - a comparison of the Boss OD-1, Ibanez TS-808, and Boss SD-1. I was surprised by just how close they are. Working out the cutoffs of the various RC combinations shows that some of the value changes between them are changes for change's sake, and don't actually affect the behaviour much / at all.
https://electricdruid.net/wp-content/uploads/2023/02/OverdriveShootout.jpg
NB: I took the FET switching out. No big deal. Most boutique pedals do anyway.
Any comments/errors spotted appreciated by PM, I'm not wanting to hijack the thread.

I think the tone control on your SD-1 is not quite right. I believe C306 is 27n and R308 is 470R on a standard SD-1?