Sustain pedal

[AdamB]

Hey,

just out of interest, is there a pedal that can be used to enhance sustain?

-Adam

[Mike Burgundy]

A compressor?

[Yun]

either a compressor or a good booster.  My re-biased lpb-2 does a very impressive job as a "sustainer" . 

You can get the schematic/layout at the layouts gallery under my gallery (Yunness). 

my DOD compressor (i have the vintage one) does the job the best, man.  i put a 1Meg pot for volume.  So it's a volume boost and a sustaining compressor....

[Mark Hammer]

When you think of "sustain", you think of something that remains at the same level for as long as you want....like a key pressed on an organ.  When it comes to taking an instrument that does not have capacity, on its own, to behave like an organ, and making it behave like an organ, there are two aspects to pay attention to.  One is maintaining a more consistent volume level across however long the sound DOES last.  The other is getting the instrument to sound longer.

Compressors try to dynamically adjust the volume level so that it remains constant.  When the input gets lower, the volume gets turned up and when it gets high, the volume gets turned down.  Of course the input signal is going to die out eventually, so the volume increase eventually gets applied to the hiss in the input when thereis nothing else to boost.

The levelling of volume for a while creates the illusion that there is increased sustain sicne there is no apparent immediate drop in volume after the note is picked/strummed.  The volume WILL drop, just not right away, and that *sounds* a bit like more sustain.

What WILL produce more sustain out of any instrument is standing near a source of physical energy that can continue to vibrate the instrument and make whatever is in motion remain in motion.  So, if you plug into any boosterand crank the amp way up, you can appear to have more sustain because the speakers are shaking the guitar and the strings keep moving longer.  If you plug into a compressor and then into a cranked amp, you get the continued movement of the instrument and strings, and the compressor superimposes a steady volume over that continued movement.  At the same time, the steady level provided by the compressor makes the amp not stop being loud enouch to shake your strings.

So, if you want *sustain*, you will need to be near speakers and use a compressor.  Note however, that virtually ANY clipping device, whether it is a diode-based fuzz box, a saturated output transformer, a preamp tube that has exhausted its voltage swing, a speaker that can't move any more forward or backward than it has, will impart some levelling of the volume.

[Eb7+9]

... the main diff between a compressor and a sustain circuit is there's typically an upper limit on available gain in a compressor whereas in a sustainer there isn't, though there is a practical limit on how far you can go anyway - simply, you have the largest possible gain range in a sustainer ...

the PAIA Infinity+ had a topology that was designed for sustaining because there's no parallel resistor across the photo-resistor in the op-amp NFB loop // different animal and quite unruly or joyfully unpredictable at onset of signal (what you don't get with comps) ... btw, many circuits that are labelled comps are mere limiters ...

if you try amp volume interaction with a sustain circuit you have to set the amp volume / distance just right so the side-chain doesn't cause over-compensation, or adjust the time constant in the averaging circuit if it operates around a charging cap ...

the Infinity+ design suffered from poor headroom (too much gain in first stage) but the basic idea can be implemented with better gain scheduling and a more linear side-chain circuit yielding amazing performance ... enough said !

~jc

[soggybag]

Sustainiac!. I have two of these. I think they are fun as heck. They will hold a note for days, weeks even, at least until the battery runs out. It's almost like the sustainiac creates a whole new instrument. There are is a lot of technique to learn when the effect is on. Muting becomes key. You can also play with the Harmonic mode and drive control for different effects.

[AdamB]

Soggy, I mean one I can build, lol. Although it'd be interesting if there is a page explaining how that sustainiac works, looks good.

-Adam

[soggybag]

I think FP made a magnetic sustainer similar to the sustainiac. There is a thread here about. I don't think this would be a good DIY project.

[soggybag]

Eb+7: The Paia Infinity sustainer + sounds like an interesting project. I googled for it and your site came up! Looking at the schematic the power supply has me a little confused, maybe you could clarify it with a few words? It looks to me like it needs a bipolar supply with two 9V? Would it be possible to make this work with a single 9V?

[Eb7+9]

yeah, it's a dual rail design - if you want a single battery version you'll need an op-amp buffered half-rail reference (see National Semi app. note on that) or you can use one of those charge-pump chips advocated here ...

this circuit is worth exploring ... notice in my re-design I'm using two opto-couplers that are matched at one test point (they have similar curvature in the response so it's sufficient) // I do it at around 1mA of diode current and read the resistance on cells until the two are close ... how necessary that is I don't know // compared to the original schematic I duplicated the output sensing circuit to produce a signal without any diode fizz coupling to the output from the detector input ... with some op-amps you could still hear something, this way it guarantees a perfectly clean output ...

with a dual supply you can run the circuit without any coupling caps in the signal path, that's how mine is wired - with a linear response down to DC, I think it really helps in keeping the transient response sharp ... as long as the offset voltages are kept low it won't affect the bias of jFET or Triode input circuits in pedals or amps following it (even then most tube amp input stages can handle a little bias anyway, 50mV won't have a huge impact) ... this way there's no phase shift in the transfer which helps keep the signal sounding as un-altered as possible - aside from dynamic adjustment ...

~jc

[bass_econo]

Ansil has one here - http://projectguitar.com/tut/sustainer.htm.  Although I haven't built it and it's not really a pedal either. 

[soggybag]

Wow, that looks incredibly simple for a magnetic sustainer. Like I said earlier I really like the sustainiac. I think it adds a whole new dimension to the electric guitar, almost makes a new instrument.