TK. Posted October 29, 2005 Report Share Posted October 29, 2005 Hi,today I made some experiments with the CEM3378 again, this time I added a virtual "distorted filter" and a delay module (both are part of the NI Reaktor library)......in order to get the typical distorted TB303 sound.Here the result - build your own oppinion, if this sounds like a TB303 or not ;-)http://www.midibox.org/midibox_sid/mbsid_demo12.mp3 (*)I'm wondering if anybody can suggest DIY schematics of analog disturtion unitsBest Regards, Thorsten.(*) the bassline is inspired from Stember_Rudolf/Logical.sid of the HVSC library Quote Link to comment Share on other sites More sharing options...
moogah Posted October 30, 2005 Report Share Posted October 30, 2005 I assume the signal chain looks like this:SID -> 3378 -> Reaktor ?Sounds good really, a nice track. the 303 sound is nice, alot to like about it, but, IMHO it is a bit generic such that I'm pretty sure I can get a similar sound from alot of synths, including VA's. As per the distortion: I've been looking into that very thing for awhile now, and, there have been few answers. Many of the disto circuits that are available have been tuned for guitar and really could be alot better for synths. I'd love to get at the circuit inside the future-retro revolution, that one is perfect for the 303. I've found the big muff to be a good starting point, but even that needs tweaking. I'm working on it, and will certianly post anything I come up with. Quote Link to comment Share on other sites More sharing options...
TK. Posted October 31, 2005 Author Report Share Posted October 31, 2005 I'm working on it, and will certianly post anything I come up with. I'm interested!Thanks for the hint, that guitar distortion units are not qualified for synths, I didn't know this - but after I noticed, how difficult it is to find adequate settings for the Reaktor based distorted filter, I believe this!Best Regards, Thorsten. Quote Link to comment Share on other sites More sharing options...
moebius Posted November 1, 2005 Report Share Posted November 1, 2005 Thanks for the hint, that guitar distortion units are not qualified for synths, I didn't know this - but after I noticed, how difficult it is to find adequate settings for the Reaktor based distorted filter, I believe this!Hi.Isn't this basicly because guitar FX units have impedance matched to high impedance guitar pickups?Bye, Moebius Quote Link to comment Share on other sites More sharing options...
moogah Posted November 2, 2005 Report Share Posted November 2, 2005 I've found guitar FX to be troublesome for several reasons. With distortion it boils down to how subtle many of the harmonics from a guitar are. There is plenty of room to totally tweak them out without just unreasonably mangling the sound. With synths the harmonics are much more 'blunt' so to speak, and distortion can often completely change the character of the sound (try distorting a chord patch other than a 5th), worse yet most stompboxes i've come across simply can't handle resononce, they boost the signal so much the peak becomes a nasty pitch-dropping harmonic, this is even worse on bass notes as it tends to form a big dissonant chord. even worse yet is that the disto lessens the effect of the filter because, say, on a square wave filtered down to nearly a sine the disto is alreade boosting the sine back to a square-like wave, hence, opening the filter can be anti-climatic. The good news is that for several reasons the 303 sound responds much better to distortion than your average synth (the resonance attenuation plays heavily here, as does only having one osc). There is a relly good primer on musical distortion here:http://www.geofex.com/effxfaq/distn101.htmOnce my x0x is finished I plan on adding an internal distortion to it. I'll be making a fairly complicted circuit on a breadboard to allow me to expiriment with many of the techniques from the primer. All will get posted here. Untill then, consider that there will HAVE to be some kind of eq before the disto, and likely after it was well. Filtering would be even better and, indeed, my best distortion patches have been made by sending the distorted output of one synth into the filter in of another. Quote Link to comment Share on other sites More sharing options...
cheater Posted November 8, 2005 Report Share Posted November 8, 2005 My take on this is that stomp boxes are made for audio singals that are.. uh - unpolarised? don't know this word in english... generally the signal is different form the typical line signal.also guitars can achieve higher signal levels i believe?cheers,d.update:i listened to the mp3. it's a nice one! but notice how when the bassline goes up a few notes, it gets "nice".. the 303 would get squelchier instead! maybe the filter needs better tuned tracking. or the resonance is dropping on high notes?i like how blurby it gets at times. real nice! i think a 303 can't do that :)generally, i'd dirty up the sound by using a resonant high-pass with env follow... but i'm a freak....speaking of env follow - try some envelope followers for generating cv, especially cutoff. it's real nice! makes the sound much more organic, "soup"-ish Quote Link to comment Share on other sites More sharing options...
moebius Posted November 9, 2005 Report Share Posted November 9, 2005 My take on this is that stomp boxes are made for audio singals that are.. uh - unpolarised? don't know this word in english... Like-- bipolar? Going + and - from the groung (or reference).. Yeah. That what it does. Like a line signal.generally the signal is different form the typical line signal.Yeah. That's right.also guitars can achieve higher signal levels i believe?Uh. No. Just a tiny one. And guitar pickups are also a huge inductive load?!Bye, MOebius Quote Link to comment Share on other sites More sharing options...
moogah Posted December 1, 2005 Report Share Posted December 1, 2005 Good news! My FET's and Zeners arrived today and my x0xb0x is up and running. I've cleared off the space on my workbench and hope to have some intereting schematics posted as early as tonight! Quote Link to comment Share on other sites More sharing options...
illogik Posted December 2, 2005 Report Share Posted December 2, 2005 Isn't this basicly because guitar FX units have impedance matched to high impedance guitar pickups?')so, change (match) the input impendance and you got a great (better) synth fx box...i know there are a lot of audiofreaks here ( consider myself one ;D ), but i think it´s good to say guitar stomp boxes have of course been used on synths-drum computers etc and can do the trick for you (it does for me)in short: i think the things moogah says are true but not everyone needs a "subtle" distortion (allthough i am of course interested in the schematics you will bring us)cheers, marcel Quote Link to comment Share on other sites More sharing options...
Jack Posted December 8, 2005 Report Share Posted December 8, 2005 Some Links to DIY Distortion Filter: (not googled, searched in guitar forums)http://www.tonepad.com/projects.asp?projectType=fx            //lot of linkshttp://www.home-wrecker.com/salvo.html                      //some demosound from DIY filtershttp://www.geocities.com/j4_student/schematics.htmhttp://smallbox.zeonhost.com/Someone tried NI Guitar Rig Demo?It works well with MB SID.Jack Quote Link to comment Share on other sites More sharing options...
moogah Posted January 4, 2006 Report Share Posted January 4, 2006 WHEW! Fair to say that I underestimated the problem is getting a good quailty VC distortion! Now that the holidays are over I've got some more time to put into this project, as well as a few new ideas. First and foremost I should mention that you would do quite well building almost any one of the stompboxes for which schematics are available, they've all been around for some time and have been built by enough people to be validated. My reasons for searching are thus: Rare parts (ie: germanium transistors) and poor design matches for synths (see above comments). Neither of these are good enough reasons to abandon the classic designs, and there are MANY of them available.If your dying for a quick fix, you can do a whole lot worse than Jonnay's "Bunny Crunch" which is a real simple and good sounding circuit which fits a 303 rather nicely. Try using a pot for R1 to get some dynamic, play around with the zeners too, there is alot of tweak space in this circuit! http://blog.jonnay.net/archives/504-Thanks-to-Synth-DIY-Crew!.htmlNow, onto what I'm pursuing. I've found schematics from electronotes for a VC clipper module based on the CA3140 and sometime soon I'll make a prototype to see how it sounds. The advantage of this circuit is that it only clips the negative side of the waveform, providing immediate asymetrical clipping. Put two of these is series with an inverting amp inbetween them and you can VC the clipping value. Good stuff. There is also some good info from Jurgen Haible about building some discreet OTA's out of matched transistors for recreating the SSM2040 (VCF from the Prophet 5). One of the great things about this filter is the gain stages are irregular and could provide some great overdrive/distortion (again, VC-able). Neither of these are going to come together overnight, but I'll post what Info I have here if people are interested in following my progress. Quote Link to comment Share on other sites More sharing options...
NorthernLightX Posted March 9, 2006 Report Share Posted March 9, 2006 Hi moogah,I'm very interested how your developments are going!As soon as my SID is finished I was planning to build a box with an AOUT and some filter modules inside (for example TK's CEM3378 filter), distortion would also be very welcome for that project, so if you would share your aquired knowledge I'd be very happy :-)Cheers, Alex. Quote Link to comment Share on other sites More sharing options...
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