Dumble Distortion Circuit Design

[silverfox]

Has anyone successfully built a Dumble style distortion circuit with an EQ and Contour control.

Silverfox.

[tubenit]

Dumble HRM (hot rubber monkey) has an EQ on the OD channel meaning a Marshall style tone stack. Not sure what a contour control is?
I use a simple 5E3 type tone control on my Dumblish inspired OD channels.

with respect, Tubenit

[kagliostro]

As Contour do you mean a middle contol ?

if so:



Tubeswell has build something with this Tone Control

http://music-electronics-forum.com/attachments/14488d1310429826-ef86-bone-ray-stack-schematic.pdf

K

[silverfox]

By contour control I mean- I've seen that sort of control on some amps. It is in addition to the Mid control. It may be another sort of depth control.


The Dumble overdrive circuit comes in after the preamp. It distorts the preamp signal. Guitar-preamp-Dumble Overdrive. I searched the Forum and found references to adding a tone stack to the Dumble circuit and it isn't an improvement.


I'm thinking in terms of using the Dumble circuit as a starting point for a Foot Switched tube overdrive circuit. Guitar-Overdrive-Preamp.


Along these lines I would also want to give it a tonal character of it's own; like any other overdrive pedal has it's unique tone- Tube Screamer etc... The object being to build a sort of mini amp out of the Dumble overdrive circuit. This would be an overdrive option within the amp I'm working on. (Just about got the power amp rebuilt on that project.)

Kagliostro- I'll look for some sound bytes of the BoneRay Tone Stack.

[Willabe]

By contour control I mean- I've seen that sort of control on some amps. It is in addition to the Mid control.

I think it might be a pot to change the mid scoop/hump? Like a Q control on a mixing board and the tilt pot on the Bone Ray TS.


               Brad      

[jazbo8]

Here is Merlin's take on the contour control, like others have said - it is a form of mid-control.

http://i81.photobucket.com/albums/j207/merlinblencowe/ParametricMidScoop.jpg

from the discussion http://www.ax84.com/bbs/dm.php?thread=412614

Jaz

[silverfox]

I saw that conversation after reading the previous posts.


I think I'm going to try something like this: http://blog.kotipolttoinen.com/archives/69-3-knob-Tone-Control-For-Guitar-And-Bass-Amps-a.k.a-The-TMS-Stack.html


But first I've got to find the poster and see how he likes the Tone Stack after some use.

Fox.

[jazbo8]

Check out the circuit simulation here >> https://www.circuitlab.com/circuit/sbzfkq/pekka-tms-tonestack/
The HF seems lower than the typical TMB stack.

Jaz

[tubenit]

The Dumble overdrive circuit comes in after the preamp. It distorts the preamp signal. Guitar-preamp-Dumble Overdrive

I'm thinking in terms of using the Dumble circuit as a starting point for a Foot Switched tube overdrive circuit. Guitar-Overdrive-Preamp.

So, it sounds like instead of having a couple of triodes (clean) with a tone stack go into a couple of triodes (overdrive) with a tone stack .................  that you'll have a couple of triodes (overdrive) with a tone stack go into a couple of triodes (clean) with a tone stack?

 

With respect, Tubenit

[silverfox]

Time to play the "Student" card, and I am.

I'm thinking in terms of what gets distorted. The guitar, or the over driven guitar signal from the preamp section.

This Forum is my tube amp theory class. It's working out satisfactorily. I'm just a few connections away from the rebuild of a power amp using the Huss-Sluckey-Tubenit power amp framework. This time I used new parts and it fits in the chassis.

Anyway, the above is how I view the differences between placement of the Dumble Overdrive. I did search the Forum prior to posting and found references to a multi band EQ in the Dumble OD as not sounding that good. I'm thinking in terms of a pedal approach to the Overdrive but not external to the amp.

Fox.

[silverfox]

Check out the circuit simulation here >> https://www.circuitlab.com/circuit/sbzfkq/pekka-tms-tonestack/
The HF seems lower than the typical TMB stack.

Jaz

The tone stack is a modified version from a Marshall Bass amp. Perhaps that explains the cut in highs.

Thanks for the link. Like I said a moment ago, I'm a student. This is something I've got to spend time deciphering. I ran the simulations but don't understand those plots very well. Just went back to run the simulation up to 15khz figuring on guitar spectrum and most hearing. Still don't understand the graph.

I'm going to guess the tone stack has reasonable affect, mostly linear, on the frequency output from high to low. There will be a phase shift in the output which will cut the output power of the signal. Perhaps I need to change a cap value to get the network to handle highs a little better. Like I said though, I'm only into this a few months now. I appreciate feedback.

Fox.

[jazbo8]

To understand what the responses are telling you, read this >> http://en.wikipedia.org/wiki/Frequency_response. In fact, when you do not understand certain terms or concepts, Wikipedia is a great source of information - even for specific topics relating to tube amplifier design.

Jaz