Guitar Effects Pedal problem in Multisim

Discussion in 'The Projects Forum' started by SJS2303, Mar 11, 2011.

  1. SJS2303

    Thread Starter New Member

    Mar 11, 2011
    3
    0
    I am trying to model up the top circuit in the image in multisim. As I do not have a jack socket input to simulate I want to use a waveform generator instead. Where am I going wrong in the schematic capture?

    [​IMG]
     
    Last edited: Mar 11, 2011
  2. bribri

    Member

    Feb 20, 2011
    133
    5
    your R3 and R4 should be pots.
    your R4 looks connected so that your output volume is turned all the way down.
    that's probably part of your problem right there.

    your R6 is 33K but the schematic says 330R

    i've never used multisim, but it looks to me like your input is set up wrong: it's looks like it's grounded.
    schematic has the negative pole of the battery wired into a trs-jack input connector. this is a guitar pedal trick which lets your input jack act as a switch (you'll never have to worry about draining your battery if your pedal is not connected to your input).

    it's really a wonderful circuit, the louder your input, the more distortion you get : )
    i highly recommend building it for real!
     
  3. SJS2303

    Thread Starter New Member

    Mar 11, 2011
    3
    0
    Thanks a lot mate, i'll give this a go and let you know how it pans out.
     
  4. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    It makes wicked distortion. I hate that kind of noise. I like high fidelity sounds.
     
  5. bribri

    Member

    Feb 20, 2011
    133
    5
    weeeeellll, put a great output amp on one side (like a marshall or hi-watt or something),
    then a great input on the other (like jimmie hendricks or someone)..
    if you still call that noise, then it's AWESOME noise :D

    track that in a good room through some neumanns onto a 2" studer at 30"/s... press that into 180g of virgin-vinyl and you're approaching hifi ; )

    i did a modification to the npn-fuzzface circuit which causes it to function like a compressor/expander... makes you feel like you're standing in a wind-tunnel! crazy.
     
  6. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    I think electric gutar players are deaf to the horrible harmonics their "fuzz" makes.
    Of course the severe distortion is noise. I like the sound of an acoustic guitar because it is played with no distortion added.
     
  7. lespaul

    Active Member

    Jan 30, 2008
    49
    2
    I have made 100's of guitar effects pedals and modified probably over a thousand common OEM pedals. The fuzz,distortion and overdrive effects are all different in their circuit design, sound and how they affect the characteristics of not only your amplifier, but your playing style as well.

    Obviously this is not to everyone's taste and as a working musician and teacher of guitar for over 30 years, I have played everything from Country to Heavy Metal. That said, not all 'fuzz' tones are created equal and its all predicated on 'your' style and what tone you want to achieve.

    If you want me to steer you in a different direction for 'overdrive' nirvana please let me know and I can email you dozens of circuit designs...some of my own and some of the more common variety.
     
    SJS2303 likes this.
  8. Adjuster

    Well-Known Member

    Dec 26, 2010
    2,147
    300
    There is something else wrong with your circuit. You have connected the input capacitor C1 to ground, instead of to the non- grounded side of the signal source. You must connect C1 correctly or your circuit will get no input, and will not work at all.

    C1 would pick up the signal from the tip of the jack plug. The sleeve of the mono jack carries the signal ground return, and also completes the negative battery return to switch the unit on (by connecting the ring terminal to ground) . You have correctly connected the battery, but you have made a mistake with the signal.

    Edit: I see that bribri spotted this before me. I also have not used Multisim - you would need to check the software instructions to see how XFG1 should be connected. At present you have the terminal labelled + grounded, which may not be right. Some simulators require connections to at least two connections on a signal source, but some may have an implied connection to ground, so only one connection may be needed. Check your instructions.
     
    Last edited: Mar 12, 2011
  9. bribri

    Member

    Feb 20, 2011
    133
    5
    oh i like acoustic also... as long as it's the good kind of music. distortion has it's place but musicianship comes first i think.

    there's also still a lot of people who hate synthesizers for some reason. i can kind of understand when it's just synthesis used to BADLY imitate various acoustic instruments, but the unique sonic possibilities brought to the world by people such as Moog and Buchla are nothing short of astounding and exciting.

    yez. i'm also a fan of the 'big-muff' pedal. it doesn't have the dynamic sensitivity of the 'fuzzface', but gives crazy amounts of sustain. based on 4 transistors, it's little a bit more complex than the über-simple fuzzface... it also tends to work much better if you bother to tune your emitter-resistors with an attentive ear. oh, and trying to match your transistors really helps.

    for sure. component selection can become quite a big deal. i've heard stories of people who tried to build Moog filters, with much difficulty. there's a lot more to it than just following a schematic.

    hey i'd also be interested : )
     
  10. lespaul

    Active Member

    Jan 30, 2008
    49
    2
    Sure fellas, glad to see more interest in guitar tones and how 'we' as designers can create new sounds. There are a million site out there with lots of the same stuff and I will spend some time going through some of my fav's and post some of my designs. Obviously Jacks site below is a great place to start. He is one of the guru's of guitar tone and I have known him for quite some time.

    http://www.muzique.com/
     
  11. bribri

    Member

    Feb 20, 2011
    133
    5
    nice site.
    i'm also a fan of this one
    http://www.geofex.com/
    as it also provides a lot of analysis and useful tips.

    cool : )

    hope i'm not hijacking the thread too much, but here's a sketch-up i made of modifications to the npn-fuzzface schematic...
    FUQQ-FACE:

    [​IMG]

    it was quite a long time ago, but if i remember rightly, the difference in most of the resistor values had to do with adapting to the choice of transistors. the highlighted lines represent the gross modifications to the circuit.
    (the 1M pot next to SW2 was a dumb choice i later realized, but whatever)

    it's perhaps not so useful with a guitar due to its characteristic self-oscillation in the absence of an input signal.
    ...but... as a drum-loop processor it's pretty darn nice... if you happen to like 'bit-crunching' / 'digital-hardcore' type effects : )
    i ended up documenting an initial test...but maybe i don't post that for now. if that schematic doesn't frighten the mods, the sounds it makes most probably will ; )
     
  12. lespaul

    Active Member

    Jan 30, 2008
    49
    2
    Hey guys, check out the links below for some interesting links on different effects circuits. Yes, geofx is a great site so I won't list it here. Most of what i have built, modified and designed is 'IN" these links. Design it, build it, play it, tweak it, enjoy it....

    http://www.runoffgroove.com/articles.html
    http://www.generalguitargadgets.com/ (good pre-drilled boards and kits)
    http://www.freeinfosociety.com/electronics/schempage.php?cat=1
    http://www.smallbearelec.com/StoreFront.bok (great place to get yur parts for guitar effex projects)
    http://www.harpamps.com/schematics/ (another great link to many circuit designs)
    http://www.gmarts.org/index.php?go=217 ( a good site for those who want to 'understand' overdrive and distortion circuits)
     
  13. floomdoggle

    Senior Member

    Sep 1, 2008
    217
    2
    That's why I play bass, Bass, cord, amp, done.
     
  14. lespaul

    Active Member

    Jan 30, 2008
    49
    2
    Guitar players are a picky bunch, I will admit that. I toured throughout the 80's as a sound engineer and most of the egos were with guitar players. Eric Johnson would swear to you that he could tell the difference between 9V Duracell's versus Energizers. We never called his bluff on it, but you get the picture. I toured a lot with Ted Nugent and he always used a monster cable cord rather than a wireless. The wireless systems back in the 80's just sucked the tone right out of your guitar. Guitar electronics effects have come a long way, but the old analog stuff still sounds the best. Overdriven tube amps and preamps still sound the best- they have much better response and tone.
     
Loading...