[sdiy] hello, I'm back.

[Scott Gravenhorst]

It just occurred to me that the VCF is an LM13600 based SVF and if the
input shunting resistors are wrong (i.e. too large) it could be that the
VCO is overdriving it.  I believe I've heard hear that LM13600 distortion
from overdrive can sound rather bad.

Is it possible that the builder made some mistakes or was trying to
modify it 

music.maker at gte.net wrote:
>Did you look at the waveforms on a scope?  "hideous-sounding VCO" is not
>what is expected, nor is that what I get from either one I have.  It's a
>sawtooth, pretty much like any other sawtooth.  The filter is a common
>SVF design, used in other synths.  I'd be interested in an audio clip
>demonstrating this sound.  After hearing it, I can tell you whether it's
>normal or not.  Both of mine sound very musically pleasing.  
>
>I think more standard complaints about the FatMan are that it's not
>patchable and not expo, however, the patchable issue can be easily
>remedied.  
>
>For a "Pros and Cons" page for the FatMan, please see:
>
>http://home1.gte.net/res0658s/fatman/FatManProsAndCons.html
>
>
>
>Metrophage <c0r3dump23 at yahoo.com> wrote:
>>--- john mahoney <jmahoney at gate.net> wrote:
>>> A common answer to "What synth should I build?" is the PAiA FatMan,
>>
>>I have a Paia FatMan synth... I don't really recommend it. I was
>>playing a few parties a couple of years ago and two kids there were
>>improvising with a Yamaha "groovebox", a portable CD player, and some
>>effects. Talking with one of the guys, he told me that what he wanted
>>to play was a small semi-modular synth. I told him that I noticed a
>>FatMan amongst their gear, and asked for opinions about it. The d00d
>>told me that he was a horrible solderer, made lots of mistakes, and
>>that the MIDI did not work- it could only drone.
>>
>>A few parties later he offered the synth to me, I offered to fix it for
>>him, but he suggested I keep it, which I thought was quite nics. I
>>fixed the rats-nest wiring, resoldered a few cold joints, clipped off
>>extra wire, cleaned the PCB, redid and organized the panel wiring. Same
>>deal when I started the unit, no MIDI. Audio signals worked fine, the
>>digital chips all had voltage and appeared to be doing their thing. So
>>I focused on the MIDI section; I replaced the 6n138 opto-isolator and
>>then it worked just fine.
>>
>>What I don't like about it is that for some reason I just really
>>disliked the VCO sound. Reminded me of a hideous-sounding VCO I tried
>>to make with a 566 function generator ic, no character. I don't
>>remember much else about it, as it is at my parents house now. If you
>>want to try a Paia kit I recommend the Theremax, which is a
>>well-thought out circuit, and sounds great.
>>
>>Then again, with its simplicity, there might be things one can do to
>>make a FatMan more fun. Some of Scotts mods sound quite fascinating in
>>the abstract.
>>
>>
>>	
>>		
>>__________________________________
>>Do you Yahoo!?
>>Yahoo! Movies - Buy advance tickets for 'Shrek 2'
>>http://movies.yahoo.com/showtimes/movie?mid=1808405861 
>>
>
>---------------------------------------------------------
>- Where merit is not rewarded, excellence fades.
>- Hydrogen is pointless without solar.
>- What good are laws that only lawyers understand?
>- The media's credibility should always be questioned.
>- The only good terrorist is a dead terrorist.
>- Governments do nothing well, save collect taxes.
>
>-- Scott Gravenhorst | LegoManiac / Lego Trains / RIS 1.5
>-- Linux Rex         | RedWebMail by RedStarWare
>-- FatMan: home1.gte.net/res0658s/FatMan/
>-- NonFatMan: home1.gte.net/res0658s/electronics/
>-- Autodidactic Master of Arcane and Hidden Knowledge.
>

---------------------------------------------------------
- Where merit is not rewarded, excellence fades.
- Hydrogen is pointless without solar.
- What good are laws that only lawyers understand?
- The media's credibility should always be questioned.
- The only good terrorist is a dead terrorist.
- Governments do nothing well, save collect taxes.

-- Scott Gravenhorst | LegoManiac / Lego Trains / RIS 1.5
-- Linux Rex         | RedWebMail by RedStarWare
-- FatMan: home1.gte.net/res0658s/FatMan/
-- NonFatMan: home1.gte.net/res0658s/electronics/
-- Autodidactic Master of Arcane and Hidden Knowledge.