Tubetype Distortion on Jack Orman’s site.

[will]

Hi,

I have some questions about the Tubetype Distortion from Patent #5,032,596 on Jack Orman’s site. http://www.muzique.com/schem/projects.htm

Just wondering if anyone has tried to build this circuit? If so how does it sound?

The working model ( http://www.muzique.com/schem/louis.gif ) was changed from the initial inverting stage to non-inverting with no change to the feedback components for both stages. I’m guessing it would be more tube like in its original configuration. Where the asymmetrical distortion artifacts are applied to the opposite side of the waveform for each succeeding stage.

I also think that the circuit could be adapted to run on a single 9volt battery by changing:
D1,D5 = 1.5 V zener diode
D2,D6 = 3.3 V zener diode
D3,D4 = 1N60 or 1N34a germanium diode.

In some ways it is similar to Stephan Moller’s emulation of the Vox AC30 many of the gain stages have the back to back dissimilar zener diodes to model the asymmetric soft clipping of the tube stage.

I would be interested in any comments related to this design or this type/style of tube emulation

Regards,
Will

[puretube]

maybe it`s possible to tickle a bit browner, 12AY7-ish sound out of this
by incresing the zenervoltages of D1/5 to 3.9V, and decreasing D2/6 to 5.6V...
for more tube-rumble, perhaps increasing the outputcap to 0,33µ would be helpful...










(sorry - just joking...)

[rodriki1]

In that circuit we have a soft clipping scheme with zener.

I have tried the one stage circuit but Zener gives a very soft clipping.

Maybe the circuit with two stages will sound more interesting.

The scheme of bias shifting was not impressive to my ears.

When i simply took of the bias shifting (diode more resistor and capacitor)

i did not fell important diference.

Try my suggestion to this design. It sound more agressive and

a tool for modern rock sound.

http://geocities.yahoo.com.br/rmfidelis/TubeSimulator.html

The email is there...

[will]

Hi Rodrigo,

Thanks for your comments. I was wondering about the bias shifting. It seems that back to back dissimilar zener diodes are popular for emulating soft tube clipping. I believe that you need at least 3 inverting stages of soft clipping to get tube like. But you also need to create the tone shaping (voicing) filtering of the classic tube amps as well. This is where the fet emulations do a great job.

I checked out your site http://geocities.yahoo.com.br/rmfidelis/TubeSimulator.html

And your tube stimulation design http://br.geocities.com/rmfidelis/tube_simulator.jpg

Your tube simulator circuit looks interesting. I wonder why you don’t think a 9v circuit will work well. I’m thinking that scaling the diodes back to ½ the current value you can run the circuit with ½ the voltage and get virtually the same response. So what kind of gain did you try in your circuit? I would be interested to know your values for R8 & C5. Perhaps putting a 50K trimpot as a variable resistor connecting to the 2 diode stacks you can vary the post gain stage hard diode clipping from hard to soft.

Regarding the clean tube sound the closest I have heard is the jiggle side of the Double D from Runoffgroove.  http://runoffgroove.com/doubled.html

I’m thinking the best will be a combination of circuits. The best I have built so far for tube like sound is my black tube highway. http://www.diystompboxes.com/sboxforum/viewtopic.php?t=20680 I did change the biasing to noiseless trimpot biasing. It is a bigger circuit than most people typically build. But it sounds really good in tube amps. I occasionally take it to jam sessions and plug it into a PA with my strat.

Regards,
Will

[rodriki1]

Tube amp

Those two words sounds misterious to me.

That is a matter that needs good care and especification.

First i am convinced after a long time, there is not really "tube sound", instead we would better say "amp sound".

I like rock music and guitars as well.

But I would like to make things more than a simple hobby.

But if i am thinking about making some money from stomp box

i need two things

- Good sound (reading good ***lation of good amp)

- Easy to find parts

And alone with short money this is like hell.

Here in brazil is not that easy to find tube amps or even mosfet.

So if i was thinking about good tube amp ***lation (sorry for the expression)

i have to do it with easy to find parts.

Inspired by John Murphy (sx100 amp - carvin), stephan moeller (vox ac30 sim),

lxh2 (fender marshall simulators) and tech 21 work, i tried (inside my conditions) (crazyyyyy!!!!!!!) to make something good enough.

When using TubeScreamer or MXR250 clones, something was not satisfied.

Two diodes for clipping always gave me fuzzy bad sound.
Using much "gain" and "great value  capacitors" (more than 100 nF) always
resulted in strange effects (noises like hell).

So i tried more than one diode for clipping (two 1n4148 in series).
low value capacitor(not too low - between 100nf <> 10nf ) This resulted in improvement.

Besides that, in circuits with simple 9 volts source the distortion simply happened
two fast or easy. I decided to raise source voltage. Things got better.

Simple common Op amps do not clip well. So i decided to make use of zener diodes that I think is not that popular. And if you observe i don't like the sound of NON INVERTER op amp so i used INVERTING op amp amplification.

The op amp must clip after diodes clipping.

Try 300k for negative feedback resistor.

(read theories of those three masters mentioned above, search google or here in this forum)

thanks for replies.