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Reworking transistor circuit as tubes? Desktop Synthesizers
Old 29th August 2007
  #1
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Tibbon's Avatar
Reworking transistor circuit as tubes?

First of all, I am not trying to take an existing piece of equipment and shove tubes in it. I know that will not work and is stupid.

However, from what I understand the transistor replaced the tube, and fit into the same general purpose.

Can you take a schematic, let's say something really really simple like a fuzz face-like:
http://www.geocities.com/j4_student/diaz.gif

Which uses two transistors...

Now can that circuit be adopted around tubes instead (obviously tubes have FAR different power requirements than transistors), and keep the other 'parts' of the circuit in tact?

I'm not looking to build a tube fuzz face.

What I would like to do however, is understand how tubes/transistors can be used in filtering. The Moog Ladder filter has 10 transistors in it's main circuit, and is buffered on the front and back by opamps (i know this can be replace by tube buffers instead).

http://dropmix.xs4all.nl/rick/Emusic..._schematic.gif

I know how a resistor/capacitor can work as various filters, but I'm still confused as to how a transistor (and maybe a tube) could be used as a filter EQ...

Does anyone see where I'm going here? Would it theoretically be possible (if not as large/hot as a Fairchild 660) to build a Moog Ladder filter out of tubes? A TB-303 filter?

Did I drink/smoke something I shouldn't have and lost my mind? I know that 'tubes aren't always the answer', but it would be neat to hear at least.
Old 29th August 2007
  #2


Tubes can be used in active filter circuits, but they have more limitations and non-linearities. This is probably what you are after anyway.




-tINY

Old 29th August 2007
  #3
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Tibbon's Avatar
Quote:
Originally Posted by tINY View Post


Tubes can be used in active filter circuits, but they have more limitations and non-linearities. This is probably what you are after anyway.




-tINY

Yep. Weird and quirky is what i'm after. Something that's very anti-digital.
Old 30th August 2007
  #4
Gear Nut
 

I don't think it is practical to use tubes for 303's filter.

Some time ago a friend asked me to make a tube buffer for his CS2X synth. With a bit of help i managed to put it inside the synth and it REALLY changed the sound to much better.

Another good "anti-digital treatment" is Gyraf's GSSL compressor. It is probably the cheapest thing you can have to give life to cold records, specially if you are recording electronic music.
Old 30th August 2007
  #5
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hangman's Avatar
 

I like the way you think.

have you seen the Metasonix stuff? I've never actually played with any of it, but it has always enspired me that they are making all tube synths and filters.
Old 1st September 2007
  #6
Gear Head
 
SuperTorus's Avatar
 

Hi Tibbon,

If you wonder what role the transistors play in this circuit, this university lecture is a must-view for you. Warning: 90 minutes, but well worth it.

http://www.stream.gatech.edu/DCRS/to...=dcrs&id=10720

Nils
Old 1st September 2007
  #7
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JohnRoberts's Avatar
 

Tubes or solid state circuitry can be used interchangeably in linear circuits with minor adjustments, but when relying upon non-linear behavior, such as in overload they can be quite different.

JR
Old 1st September 2007
  #8
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r0ck1r0ck2's Avatar
 

Quote:
Originally Posted by SuperTorus View Post
Hi Tibbon,

If you wonder what role the transistors play in this circuit, this university lecture is a must-view for you. Warning: 90 minutes, but well worth it.

http://www.stream.gatech.edu/DCRS/to...=dcrs&id=10720

Nils
thanks for the link!!!

any others?
Old 1st September 2007
  #9
Gear Head
 
SuperTorus's Avatar
 

Quote:
Originally Posted by r0ck1r0ck2 View Post
thanks for the link!!!

any others?
sure -

ECE4803B: Theory and Design of Music Synthesizers

Have fun...
Old 1st September 2007
  #10
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r0ck1r0ck2's Avatar
 

let us all admit at this point that the professor in these clips is a 1st class dork/nerd
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