[sdiy] Transistor help

[Bob Weigel]

Ahh yes of course in locations that are common mode voltage sensetive it 
would certainly be a good idea to use matched.  Isn't always handy to 
stick a CA3046 in there, but hey I've done crazier looking things :-)  -Bob

Harry Bissell Jr wrote:

>Transistor matching will show up the most in
>control voltage breakthrough in a ladder filter.
>
>using 'unmatched' transistors does not mean that
>they are 'not' matched... just that you did not
>test for that parameter.
>
>Given the choice between unmatched transistors
>in VCF, VCA etc... I go for matched. I'm mostly using
>monolythic pairs, or arrays. They sound much better
>than the dumb luck filters I've tried.
>
>CA3046 is like $.25 each in quantity, so why not
>use 'em. ARP and Moog both did...
>
>H^) harry
>
>
>
>--- Kevin Lightner <synthfool at synthfool.com> wrote:
>  
>
>>>Hi,
>>>Whats the point of matching transistors (in expo
>>>      
>>>
>>converters and ladders),
>>    
>>
>>>beyond 2mV?
>>>Is there really a sonic difference? Do we need
>>>      
>>>
>>expensive 0.5mV matched
>>    
>>
>>>arrays or just transistors from the same batch?
>>>
>>>Emperors new clothes? Or State of the Art?
>>>
>>>An E-mu Systems Resonant Filter I have recreated
>>>      
>>>
>>sounds better with
>>    
>>
>>>unmatched 2N3906's rather than a dual transistor
>>>      
>>>
>>pair (as per the
>>    
>>
>>>original).. any thoughts guys?
>>>
>>>Regards
>>>Rob
>>>www.emulatorarchive.com
>>>
>>>
>>>One thing I have noted about modern batches of
>>>      
>>>
>>transistors is they sure
>>    
>>
>>>seem to be all very similar...I generally match
>>>      
>>>
>>about 10 pairs at a
>>    
>>
>>>time...out of 20 transistors (generally 2n3906) I
>>>      
>>>
>>always get 10 pairs...and
>>    
>>
>>>all of the transistors are within about 2mV of each
>>>      
>>>
>>other....30 years
>>    
>>
>>>ago...it wasn't like that...as I recall.
>>>      
>>>
>>I'm curious how the two were A/B'd unless you made
>>duplicate filters. :)
>>
>>However, transistor matching, in my opinion, is
>>blown out of proportion.
>>I'm not sure most people can hear a filter and say
>>it sounds like the 
>>transistors are unmatched or whatever. I've also
>>built Moog filters 
>>with completely unmatched transistors, even from
>>different makers and 
>>they sounded great.
>>
>>It's funny about all the rumors out there in regards
>>to matching too.
>>For example, there's a rumor that only the early RA
>>and Musonics 
>>Minis used matched transistors in their ladders.
>>I have 11 (count 'em!) Minis in and they ALL have a
>>colored dot on 
>>their transistors, which the other same numbered
>>transistors don't 
>>have. The reason, often overlooked, about the very
>>early Minis is 
>>that their electrolytic caps are older and of
>>different values when 
>>new anyways.
>>400uf, instead of the later 470. 80uf instead of
>>100uf and so on.
>>Their carbon resistors are often *way* off too.
>>I often measure the 820 ohm resistors at 1K-1.2K.
>>
>>
>>-- 
>>Regards,
>>Kevin Lightner
>>
>>Myself: http://www.synthfool.com
>>Service and sales:
>>http://www.moogmusic.com/service.php
>>Sales: http://www.cluboftheknobs.com
>>
>>    
>>
>
>
>  
>