[sdiy] TB303 transistors

[Fierce Fish]

Tom, in your opinion does the 3031 nail the 303 square wave? I have yet 
to find a clone that can sound like my 303's square, most clones on the 
market can do a very convincing distorted sawtooth acid stuff, but for 
the more refined fluid square wave stuff they all sound way off to my 
(not that good) ears!

Anyone else have any thoughts on this, I'm starting to believe some of 
the conspiracy theories that aliens from the future designed the 303, 
the square wave sound is like the holy grail or something. Godammit! ;)


On 24 May 2005, at 19:51, Tom Arnold wrote:

> On Tue, May 24, 2005 at 07:10:02PM +0100, Fiercefish wrote:
>>    I am keen to try to get the classic 303 square wave sound which is
>>    very different (as is well documented) from any other synth, any
>>    pointers on which transitors would be a better substitute (BC327,
>>    BC557?) Also is the gain of the transitor affecting the waveshape 
>> or
>>    PWM in a strange way in the 303? Why does it sound SO different?
>
> Tony Allgood points out that the TB303 uses two different 2SK30's, the 
> Y and
> the O.  The O is hard to get, a Y ships with the x0xb0x.  I believe the
> transistor in question is Q28.  If you look at the TB3031 docs he talks
> about Why -O's are different from -Y's ( differing Idss ) and that the
> Squarewave is dependant on the -O's Idss, so he uses a J201 unstead of 
> a
> 2SK30 in that position.
>
> Personally I have a TB3031 because it can sound like a TB303, and I'm 
> building
> an x0xb0x because it'll be a neat toy, and maybe after its built it 
> can be
> tweaked in to sound a little closer to the original.  x0x should arrive
> Friday... I figure I'll have it built by Midnight PST if not sooner...
>
> -- 
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