stomp boxes

Discussion in 'The Projects Forum' started by Neil Groves, Sep 17, 2012.

  1. Neil Groves

    Thread Starter Member

    Sep 14, 2011
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    Hi guys, i was just given an electric guitar for my birthday and i immediately started looking for stomp boxes to build, even though my amp is more than capable with the vast amount of effects available i would still like to build my own out of interest, i have read much about 'tube' this and 'tube' that, what are tubes and why are they so popular?

    Neil.
     
  2. MrChips

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    Oct 2, 2009
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  3. danrulz98

    New Member

    Sep 17, 2012
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    I do a lot with musicians... Tubes are popular because of the sound. It's warm and natural feeling, where transistors don't necessarily add any character to the sound.
    Another reason is how tubes react when you push too much signal into them vs. how transistors react.. Link to image (excuse my crude drawing). When the transistor clips, its much more harsh and nasty sounding than when the tube is driven to distortion. That tube distortion is what a lot of guitar players prefer.

    At least, this is how it was explained to me by a radio engineer...
    If you listen to something being played through a tube amp, and listen to the same thing through a solid state amp, they do sound very different.
     
  4. MrChips

    Moderator

    Oct 2, 2009
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    You are quite right but the two reasons are the same.

    When a solid-state (transistor) amplifier clips, it turns sine waves into square waves. This adds odd harmonics to the sound.

    For example, a pure A-note at 440Hz when clipped will add the notes E, C#, F#, B,
    a bit like a F#m7 chord but hardly sounds like it.

    A tube amp has more elasticity. Instead of clipping, it saturates gradually and acts like a compression circuit. This avoids nasty higher harmonics. Thus the sound is "warmer".

    A carefully designed solid-state amplifier (especially with DSP technology) can recreate the same effect as a tube amp if that is what the musician prefers.

    On the other hand, heavy metal rock bands intentionally use clipping circuits in order to add their characteristic "fuzz" sound.
     
  5. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    Good post! :) Tube amps also sound warmer because of the large laminated output transformer which has a number of effects on the sound.

    There's also "pumping" where the percussive attack of the guitar is louder and then the main caps in the tube amp drop some voltage due to the high PSU impedances, which works well with rythm guitar playing. It was popular many years back to modify amps to adjust pumping by changing PSU series resistors or even switching on some early models between a valve rectifier and a solid state diode rectifier.

    My suggestion Neil if you want to play with some great sounds get a small tube amp and overdrive it directly to the output stage. One of the best sounding amps I ever played was a crappy 10W 1960's turntable hifi thing, where I connected the guitar into the input from the magnetic turntable pickup. Overdriving the output stage hard sounds better than most input overdriving because the output transformer is a big part of the effect. No tube based stomp box (that I know of) will get that sound.

    And of course if you try it on a big amp 60W or above it will really cook and the sound level will blow your head off, so it's a bit hard to get that sound on big amps too.
     
  6. Neil Groves

    Thread Starter Member

    Sep 14, 2011
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    Thanks for the info guys, i'm gonna stick with trannies for my stomp boxes (at least the first couple though) as everything i build right now i manage to screw up and have to debug, so i am shying away from high voltage (line voltage) circuits.

    thanks for the explanation though.

    Neil.
     
  7. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    Cool, it's wise to stay away from line voltage and HV projects if you have any trepidation.

    Some time ago I saw on one of the stomp box sites a guy made a front panel with some 6.5mm guitar jack sockets, and some switches and pots, and thin wires coming off all the stuff. Then behind on a flat plate he has some plugin breadboards. The whole setup looked very effective for putting together a circuit and playing his guitar through it.

    Or could be used to replicate a classic pedal circuit and then change parts values to see the effect, or to replace a fixed resistor in the circuit with a pot and then he could turn the pot when playing and see the effect etc. It was a great idea I thought.
     
    Neil Groves likes this.
  8. Neil Groves

    Thread Starter Member

    Sep 14, 2011
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    I just looked at the prices for ready made stomp boxes and it seems it is cheaper to buy them than make them after taking into account the hardware involved, so really the only advantage is that you get the enjoyment out of using something you built yourself and you get the pleasure of hands on construction and that you can make mods to see different effects.

    I know lead is supposed to be bad for you, but i just love the smell of solder fumes and a hot soldering iron lol

    Neil.
     
  9. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    Sure there's the enjoyment and satisfaction, but don't forget you can also make things that are "classic" and no longer available like an exact replica of the fuzz box Hendrix used on Watchtower or the wah pedal he used on Voodoo Chile.

    I saw the fuzz box schematic, it used one PNP germanium transistor and about 6 discretes. There you go; sound just like Hendrix for the cost of ONE transistor. ;)
     
  10. danrulz98

    New Member

    Sep 17, 2012
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