CE-2 Chorus Ensemble **PICTURE!** SOUND SAMPLE!*

[Mark Hammer]

http://www.generalguitargadgets.com/boss/BossDC-2.gif

Chorus pedals  are a lot like tube amps.  There are some things you absolutely HAVE to do for a tube amp, so a lot of them look very similar in design.  The same is true of choruses.  You HAVE to have an LFO.  You HAVE to have lowpass filtering, and you HAVE to have a mixing stage.

So how are choruses different from each other?

• The delay range selected has a huge impact on the character of the chorus, as well as on other aspects of the design of the circuit.  Using a longer delay directs the listener's attention to different aspects of the sound that a short delay does.  At the same time, because of the sorts of clock changes created to produce that delay time, the filtering has to compensate, and ultimately the tone of the delay signal is affected by doing so.  Some pedals will have delay range select via toggle, or a continuously variable initial delay control.  A DOD floor multi-FX I have has this.  Unfortunately, because the filtering is in anticipation of what would be needed for the longest delay time, the shorter delay times lose some critical sparkle.  Variable delay range CAN work, but not everybody does it well.  I have a range select switch in every analog chorus I own (Zombie, Small Clone, CE-2, Washburn SC-7), and I wouldn't want one without it.
• The LFO or sweep generator's speed range can be different, based on what speeds sound good given the delay range selected.  For instance, if a shorter delay range is used, then slow speeds, comparable to a flanger, can be used to produce nice swirly sounds.  If the delay range is longer, then the speed range will likely be more restricted, because fast speeds sound sick at long delays, and slow speeds don't benefit unless the delay time is short enough.
• Shaping of the delay signal properties.  The basic chorus pedal will simply vary LFO properties of Speed and Sweep Depth.  More complex ones may have a control to adjust delay signal level at the mixing stage, or delay tone.  These generally serve to produce a subtler, more nuanced chorus sound, rather than a more intense sound than might be achieved from a basic unit like the CE-2.
• Alternate speeds and/or modulation sources.  The CE-1 was intended to be optimized for keyboards, but also to allow for faking Leslie effects.  Switching between chorus and vibrato effects not only switches between speed presets, but also between sweep waveforms.  Other than deliberate clones of the CE-1, like my buddy Tim's Retrosonic Chorus Ensemble, not many products have speed presets that use different waveforms for slow and faster speeds.  At least none that I know of.  I'm sure there are regionally known boutique pedals that do this...somewhere.
• Output options.  These can include dry/wet stereo (which is what the JC120 used, employing separate power amps for each speaker and routing wet only to one channel), or sum and difference outputs (dry+delay vs dry-minus-delay).  Since vibrato involves oly feeding the wet signal to the output, I guess you could cal this an output option too.

Just about any of these characteristics can be built into any chorus, though not necessarily in so simple a manner that a mere component change on the board will nail it.  There is also the question of whether the chassis will accommodate whatever additional controls you would need to add, and whether they could go somewhere where clock noise would not be an issue.  In the land of the hypothetical, though, they can all be done because obviously someone has already done them.

These are all differences in single BBD devices, though.  Circuits like the DC-2 use two and sometimes more BBDs to achieve a "wobble-free" chorus sound.  Here, multiple BBDs either have their time delay counter-swept so that one is always higher when the other is lower, or else have each BBD time-swept independently in some other manner, such that there is no obvious up and down sweep to the listener's ear.  These tend to be much more pleasing and less fatiguing to listen to *because* they are less obviously periodic.

[rocker-D82]

I'd say try any dual opamp, quite a few should work.

Fp

I use a TL072 instead of TL022. My chorus sound nice with battery (I hear a very low low "tick"), but with power supply is not playable (a lot of hum!). What is the problem?





For FP... If you wish, you can use this images for your site! 

[Fp-www.Tonepad.com]

Rocker, nice build. It really looks very crowded in there!

I'll use your pictures thanks!

Fp

[lowstar]

today i did a close comparison between my original ce-2b and the corral chorus. (my build report: http://www.elixant.com/~stompbox/smfforum/index.php?topic=42954.0)
i used tl022 for the lfo, incorporated the bassmods (wet bass/fx level). no ticking probs after i shortened the rate wires.
for the testing, i set the fx level on full (i had to use 250k lin poti cos i could not find a revlog) and the rate and speed pots to 1/2 on both units. somehow, i found the original to be warmer, there are a little more modulations underneath the modulations going on, hard to describe.
nonetheless, i am very very happy with it. not that it sounds worse, just a little different.
i you stop to a/b and play it in a band setting, it sounds just like it should.
btw, i set the trimmer so the bbd sees a voltage of 4.5. is this correct or should i rather do it by ear ?

a big thumbs up to francisco ! 
p.s. how bout a bf-2 ?? (hint hint)