Moog filter schematic?

Discussion in 'DIY Pro Audio Forum' started by Learner, Oct 28, 2003.

  1. Learner

    Learner Guest

    Hi guys,
    I am looking for Moog lowpass filter schematic, don't mean to dis Bob Moog but $250 for a RC or RL network is a bit out there for me....... :eek:
     
  2. Steffen

    Steffen Guest

  3. Learner

    Learner Guest

    WOW!!! AWSOME stuff Steffen!!! [​IMG]

    Your a champion!!! [​IMG]

    I was actually looking for the Moogerfooger lowpass filter schematic to be used as a bass pedal, do you think the envelope and the filter is the same on the mini? [​IMG]
     
    Last edited by a moderator: Mar 31, 2014
  4. Steffen

    Steffen Guest

    I´ve never had a fooger...so I don´t know....

    steff
     
    Last edited by a moderator: Mar 31, 2014
  5. Shalimar

    Shalimar Guest

  6. PRR

    PRR

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    > $250 for a RC or RL network is a bit out there

    It is a hell of a lot more than "a RC network".

    And "dis" him all you like: Bob has a patent on that voltage controlled filter. It works much better (phatter) than any other. Back in the day (before the miniMoog was introduced), other synth companies either had a lame-sounding VCF or risked lawsuits by stealing Bob's design (they lost).

    The pedal you point to also has an envelope generator. If it works "automatically", then it must also have a trigger generator. Oh wait: it has an envelope Follower, a non-trivial circuit.

    Hmmm... I could probably set up the patch on my ARP 2500. That's a real synth, a clone of the original Modular Moogs, not a miniMoog. Probably take an hour to patch, might take days to get it to trigger reliably from live playing. And it would be the hard ARP VCF, not the sweet Moog VCF. The ARP 2600 is 5 feet wide, cost $20,000 new (a loooong time ago); not good for live gigs. And I'd probably have to do some outboard crap to make it envelope-follow.

    Give Bob the $269. His stuff is worth the price. For one example: I just saw one of the first miniMoogs (a model D) in concert, working well, and it has never needed a single repair.
     
  7. Shalimar

    Shalimar Guest

    Lotsa fun can be made with a Korg MS20 as well!
     
  8. clintrubber

    clintrubber Guest

    I've built the VCF-1 from the site below. Bought the PCB and got the parts myself.

    http://www.oakleysound.com/

    The VCF-1 is discontinued now, but has same follow-up designs, see that site. And yep, it's
    the voltage controlled Moog ladder, up to a fourth order LPF.

    My original application was electric bass. It sounds good, but for bass you might probably be equally served with something simpler.
    All the 'synth-addons' of the VCF-1 are interesting though, but probably overkill for stage-use for electric bass if that's your application as well.

    BTW, not an advertisement, but the Oakley stuff is well made. Good PCBs at OK prices and if you have questions he (Tony Allgood, the man behing Oakley) is very helpfull.

    Bye,

    Peter
     
  9. clintrubber

    clintrubber Guest

    Don't know if you mean for elec. bass and if you're specifically after a Moog filter, but a Mutron III can be made quite easily. Lot's of schematics/clones around - or buy the III+. Or the Ibanez AF-9 (?).

    FWIW,

    Peter
     
  10. clintrubber

    clintrubber Guest

    Finally, whatever circuit you end up with to DIY,
    don't let it be the ElectroHarmonix BassBalls. It's simple, easy and above all cheap in every aspect (imho). I built one. It's fun, but not as your main filter. In a class of its own... enough said.

    Peter
     
  11. idlefaction

    idlefaction Guest

    if you've built stuff before, the moog filter pcb at http://www.ele4music.com/ is also worth checking out and VERY inexpensive.

    if you're looking for a fantastic envelope follower to marry to it, harry bissell made a really amazing one. it used to be on e-insite.net but i just went there and it's gone! i have the schems tho - if you like i can mail them to you. [​IMG] it uses Logic chips and is pretty complex, but then an envelope follower is a tricky thing to do well.

    if you're brave you could rip the envelope generator out of an 1176 or LA4 and see if that sounds good!!!

    one thing to note is that relative to normal stompbox use, these circuits do pull lots of current so you'll need to run it off a wall wart. even worse, if you want to use a 9V wall wart you'll need to use a charge pump to get the +/-10V or +/-15V needed!

    try the message board at:
    http://www.ele4music.com/forum/forum.asp?FORUM_ID=1

    good luck!!
     
    Last edited by a moderator: Mar 31, 2014
  12. idlefaction

    idlefaction Guest

    also, there is a 9V schematic for a moog ladder filter floating around the net made by Tom Something-or-other, and it doesn't work so don't bother building it. he gave up on it many years ago, but it still floats about. it ran the ladder bit at 7V and the exponential converter at 2V or something, but nobody could ever get it to go.

    i went through what you're doing now about a year ago and did heaps of research and in the end decided i'd have to learn craploads of electronics and design a moog filter from the ground up using germanium to get it to go on low voltage at low current. non-leaking, matched germanium. [​IMG]

    but yeah, a wall wart with a charge pump and the EFM module plus an envelope follower from somewhere like www.diystompboxes.com should get you going. (it's what i use in my guitar rig.)

    HTH! i'll stop posting now.
     
    Last edited by a moderator: Mar 31, 2014
  13. Learner

    Learner Guest

     
    Last edited by a moderator: Mar 31, 2014
  14. Learner

    Learner Guest

    Don't know if you mean for elec. bass and if you're specifically after a Moog filter, but a Mutron III can be made quite easily. Lot's of schematics/clones around - or buy the III+. Or the Ibanez AF-9 (?).

    FWIW,

    Peter
    [/QUOTE]Yes, well kinda. I am trying to understand this VCA and VCF thing circuitwise to see how it actually works and hopfully incorporate into some mutant outboard compressor or something......tweakin tweakin sound.... :D
     
    Last edited by a moderator: Mar 28, 2014
  15. Learner

    Learner Guest

    Yea, certainly is fun for exploring and modulating. But I can't seem to get a fat sound out of it, it can be very good at grungy noises thin or nasal......

    heh....donno what this all means in terms of electronic circuitry design but I would love to find out!!! [​IMG]
     
    Last edited by a moderator: Mar 31, 2014
  16. thermionic

    thermionic Guest

    FWIW, The first ARP 2600 had a filter that was completely potted...This was because they copied Bob Moog's! These 2600s fetch more s/hand than the proprietary ARP filter on later editions.


    http://www.till.com/articles/moog/patents.html
     
  17. PRR

    PRR

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    > no way in a million years of finding out the secret getting that fat sound huh?

    No, the whole purpose of Patent is so new inventions can be revealed and marketed for the benefit of "all", while the inventor has some opportunity to profit. Thermonic has posted a link to the public patent. That shows the novel parts of the invention, but skimps on some practical details. Someone here posted a link to the the service-manual for a miniMoog, and that is clear and easily duplicated.

    Before patents, inventors had to keep their work secret.

    Anyway I suspect this patent is expired. If it isn't, Bob is not going to shoot you for making one personal-study unit.

    Most multi-pole filters derive from Analog Computer concepts. Like Active Crossovers, the goal is maximum precision. If you overload them, they go "splat" in annoying ways.

    Bob's VCF is less precise, but has an interesting overload sound, and is incredibly cheap. I think you need to learn a lot more about transistors to understand it, but you don't need to understand it to build it.

    As someone noted, the sidechain in a limiter is an envelope follower. One problem: control voltages can be linear or exponential. Bob's filter is cleverly (though not exactly) exponential, to track a 1V/octave system control standard. I suppose it could be modified to be linear (though his semi-exponential converter is incredibly clever). Or there are several exponential limiters around here.

    > excuse my ignorance

    I won't excuse it; I'll try to cure it. That's impossible (nobody really teaches, only you can learn), but I can try to bump you down the path to lesser ignorance. Don't mind me too much if I bump a little hard.

    > a RC or RL network

    "Just" an RC network would be fixed frequency; if you put a pot on it you have a tone control. Yes, those are cheap.

    This VCF can be controlled by a voltage (such as a Moog keyboard, or the shape of the signal from an instrument). That's amazingly hard. It is also 4-pole, which tends to be more than 4 times harder than a simple 1-pole filter (standard treble control).
     
  18. clintrubber

    clintrubber Guest

    FWIW, note a lot of fun seems to be possible
    with toying around with the 4-pole ladder. Taking signals
    at various places of the ladder and/or polarity flipping can give all sorts of responses, even 'some sort of bandpass'. If interested look further for this at the mentioned Oakley site, his post-VCF-1 designs elaborate on these possibilities.

    Peter
     
  19. Learner

    Learner Guest

     
    Last edited by a moderator: Mar 31, 2014
  20. idlefaction

    idlefaction Guest

    pretty sure the layouts aren't clear so that you have to buy the board aye ;) the kit will come with clearer instructions.