VibraChorus

Classic chorus with many options, including vibrato

 

 

 

The VibraChorus chorus rack effect module is really two effects in one.  The chorus compares to the Boss CE-2 (and CE-2B for bass) and Ibanez CS-505 chorus pedals.  The vibrato doesn't compare to a specific vibrato, but it is built like a vibrato should be, unlike the vibrato option found on many choruse pedals.  The chorus and vibrato use different waveforms, which is critical to getting both great chorus and great vibrato.

 

Description

The Boss Chorus Ensemble pedal has gone through several versions over its decades of production, but the CE-2 (and CE-2B Bass Chorus) were among the most popular and are still sought after today.  The circuit has been copied many times and is still the base circuit for many chorus pedals made by several manufacturers.  The CE-2 serves up great tone, in a simple manner.  It has only two controls for Rate and Depth.  While the simple control set allows for a variety of great chorus tones, there are many tweaks that can be made to provide much more flexibility.  We offer several of those tweaks in our VibraChorus module.  Most of the options offered still allow the stock CE-2 sounds, providing additional capabilities, as opposed to permanent changes that force a choice between the stock sound and the modified sound.

For purposes of discussing the options, we'll divide the circuit into 3 parts:  the audio portion, the delay, and the LFO.  Your guitar sound travels through the audio portion.  It also goes through the delay, but that is a special part that we will handle separately.  The LFO, or low frequency oscillator portion of the circuit controls the delay.  Your guitar signal does not pass thru the LFO, so changes there do not affect your tone.  Changes in the LFO affect the range of control for the effect, such as the Rate and Depth.  Most of the options affect the LFO and delay controls, not the tone of the circuit.  The audio portion of the circuit remains pretty close to the original circuit.

The VibraChorus is one of several modules where we build the circuit on multiple boards.  This helps remove "lock noise"from those circuits, which plagues some pedals even from top builders.  We simply have more room to work with in our rack format, so we can take additional noise reduction steps that are not practical in a standard pedal format.  And with that extra room, we can also offer more options on those boards.

The original CE-2 used the obsolete MN3007 chip and its associated MN3101 clock, running at 15V, in the delay portion of the circuit.  The MN3007 (and other MN300x) chips are the heart of many great effects.  The MN3007 was later replaced with a newer version, the MN3207, along with its associated clock, the MN3102.  The MN320x chips were also widely used in many great effects after the MN3007 was obsoleted.  Both the MN3007 and MN3207 chips went out of production, are often counterfeited, and getting somewhat difficult to find from reputable sources.  But they are still somewhat available at rising costs.  The MN3007 was recently revived and is available again, identical to the original.  We offer both as options.  The main difference is that the MN3007 will run at 15V and the MN3207 will run at 9V.  Either is generally fine, but you will have some extra headroom with the 3007, and it is sometimes noticeably better.  There are also modern substitutes for these chips, but at present we are still offering the MN3007 and MN3207 due to their superior tone.  This is one option that is not switchable.  You must choose which delay you want.  Either sound great, but we give the edge to the MN3007.

The CE-2B was a slightly modified version of the CE-2 specifically for bass.  It has only 2 differences from the standard guitar version.  One is a different capacitor in the wet signal.  The other was the "E. Level" or Effect Level aka Mix or Blend control.  In many bass effects, the wet signal is mixed lower to allow a higher percentage of dry signal in the final mix.  This control starts with the standard 50-50 mix of dry to wet but allows you to reduce the amount of wet signal.  It does not allow you to increase the amount of wet signal above 50%.  If you select this configuration, the capacitor change can be put on a switch so that you have both the bass and guitar values available, or you can have the pedal hardwired for bass if you don't want unnecessary switches.  The Blend control will give you the stock 50-50 mix at one extreme, so with the capacitor on a switch, you can still get the stock guitar tone, too.

The CE-2B changed that capacitor value so that the original bass notes you play are NOT sent through the chorus effect.  That keeps the bass notes tight, not muddy.  The harmonics do go through the chorus effect.  This can make the chorus seem a bit subtle (compared to guitar chorus, particularly 80's style guitar chorus) unless you crank up the Mix control.  But it keeps your rhythm clean while adding the chorus effect on the top end.  This cap can be put on a switch so that you also have the CE-2 guitar value cap available, which does let more bass through, although that seems counterintuitive.  You can also opt for the Deep switch.  The Deep switch doesn't change the bass content, but it makes the effect more pronounced. 

A close cousin to the CE-2 is the Maxon Insta-Chorus CS-505, also known as the Ibanez Chorus CS-505.  The Maxon and Ibanez pedals are identical except for the enclosure, paint, and graphics, which is not surprising since this is another pedal built by Maxon for Ibanez.  The audio portion of the circuit has much the same design as the CE-2, and we build it on the same board as the VibraChorus.  But the audio portion is slightly different and has some different features and filtering.  This build is our VibraChorus CS-505 configuration.  In addition to some different filtering in the audio portion, the LFO is also different.  The LFO provides only simple Rate and Depth controls by default.  The range of these controls provides a different character to the chorus from the CE-2 configuration.  The CS-505 also has a built-in noise gate.  The chorus effect works by mixing the dry signal with the wet chorus signal.  The wet signal is processed through the BBD delay, which can add a little analog noise.  The noise gate chops off the wet signal when it fades down to very low levels.  That means if you leave a note hanging for a while, as the effect fades out you would normally expect the BBD noise to become more noticeable.  Instead, when the effect gets so low as to be nearly inaudible, the effect path is shutdown, leaving only the dry signal.  This is very subtle, but also very effective for low, slow playing.  You get less noise.  If your notes aren't allowed to fade out, then the noise gate doesn't kick in and you just get your nice chorus the whole time.

As 80's effects and tone continue to creep into today's music, the CS-505 remains a preferred vintage chorus.  It is simple, enhances your base tone, works with distortion and overdrive well, and doesn't go into the over-the-top spaceyness that remains firmly in the hits of the 80's.  If you almost like the CE-2, then the CS-505 might be a good alternative to check out.  Or perhaps you need an alternative to reverb to make your sound bigger.  The CS-505 can do that in a classy way.

While the CE-2 configuration can get spacey and seasick, all settings on the CS-505 configuration are very usable.  The delay section is similar, using the MN3007 BBD chip running at 12V.  Overall, the chorus is rich, smooth, thick, and natural.  It is no wonder that vintage CS-505 chorus pedals are still in demand.  It's a great chorus, without the over-the-top settings that might be found in other 80's chorus effects.  A few interesting options are available, described below.  However, some of the other options available for the VibraChorus and VibraChorus Bass are not compatible with the CS-505 config, so mind the details below.

 

Configurations

  • VibraChorus - compares to Boss CE-2 Chorus Ensemble and numerous copies and clones.

  • VibraChorus Bass - compares to Boss CE-2B Bass Chorus

  • VibraChorus CS-505 - compares to Maxon Insta-Chorus CS-505 and Ibanez Chorus CS-505

 

Options

  • MN3207 BBD - Choose MN3007 or MN3207, as described above.  MN3007 is the default.  Not recommended for CS-505 config.
  • Custom Bass Capacitor (no switch) - Choose either the standard bass capacitor value (recommended) or another value to let more bass through.  Not for CS-505 config.
  • Custom Bass/Guitar Capacitors (switched) - Choose 2 capacitor values, probably the standard bass and guitar values, or maybe the standard bass capacitor and a "more bass" capacitor.  We can assist with this.  Not for CS-505 config
  • Deep Switch - This is a tweak in the LFO to allow more Depth in the effect.  It increases the range of the Depth control.  This can either be hardwired or put on a switch so that the stock values is the other setting.  This is the switched version. 
  • Deep Mod - This is the non-switched, hardwired version of the Deep Switch.
  • Speed Switch - This is another LFO tweak that allows for different ranges of the Rate control.  Some players want a faster range, some want a ssslllloooooowwww range.  This switch will have 3 positions/settings.  One is the stock speed, one is faster, and one is slower.  The stock range is about 1 cycle in 4 - 5 seconds on the slow end up to about 10 cycles per second on the fast end.  The faster range is about 2 seconds per cycle to 25 cycles per second.  The slower range is about 9 seconds per cycle to 5 cycles per second.  Not for the CS-505 config
  • Delay Control - Some like to have control of the length of the delay in the chorus effect.  This LFO change provides a control that lets you adjust the Delay.  Its range of adjustment includes the stock delay time.  The length of delay can have a substantial impact on the overall effect, particularly with the CS-505 config.  Normally this is an internal trimmer.
  • Chorus / Vibrato Switch - Chorus and vibrato effects are technically similar.  Chorus mixes the wet and dry signal at a fixed 50-50 proportion, and uses a triangular wave form to control the delay.  Vibrato uses only the wet signal, but it sounds better with a sine wave instead of a triangle wave.  This gives you a twofer - a module that is either a good chorus or a good vibrato with the flick of a switch.  Most chorus pedals that give you a vibrato switch use the triangle wave for both chorus and vibrato, which isn't quite right for vibrato.  The switch will change from the stock CE-2 chorus 50-50 mix with the stock triangle wave to a vibrato with a sine wave.  This option is included in both configurations.  Not available for CS-505 config.
  • Tilt Control - The sine and triangle waves are symmetric in shape.  They go up and down at the same rates.  But it is possible to tilt the shapes to get some interesting tweaks to the wet signal.  The Tilt control allows you at one extreme to ramp up very quickly and ramp down slowly, and at the other extreme ramp up slowly and ramp down very quickly, with various levels of subtle change in between.  At the midpoint, the shape is symmetric, removing the Tilt effect.  This gives you more control over the volume swells, allowing you to accent either the rise or the fall.  Not something you need to do in every song, but maybe just that little something you need once in a while to change things up a little.  Not available for CS-505 config.
  • Threshold Control - This is for the CS-505 only.  It gives you a control for the noise gate.  At low settings, you'll get a chorus effect that quickly changes to a dry only signal.  At high settings, the wet signal will continue as long as there is dry signal.  In the middle, it behaves like the original CS-505 pedals, cutting off the wet signal when it gets low enough to be mostly noise.  The control gives you an interesting brief chorus effect, and also allow you to adjust the noise gate to the level of noise you are experiencing.
  • Original Transistors - The original CE-2 used a combination of 2SC732 and 2SC945 transistors.  The original CE-2B used a combination of 2SC2240 and 2SC945 transistors.  The CS-505 used 2SC536 transistors.  Some of the transistors are in the audio path and some are in the LFO.  We can use the original parts if you want them.  Or we can use modern, low noise transistors that we think are an improvement.  The originals were basically just inexpensive, mass production, readily available parts at the time, and don't likely have any detectable mojo, other than maybe a little bit more noise.  We will use the modern replacements by default.  The originals are a bit more expensive, and several of them are used.
  • Original Diodes - The original pedals both used 1S2473 diodes.  These diodes are not in the audio path, so they do not contribute to the tone of the circuit.  They are in the LFO, common available diodes work just as well there.  1S2473 diodes are getting hard to find, and expensive.  We try to keep some in stock, but we prefer to use them in other modules where they do impact the tone.  They do no good in this module, but if you want the originals, we can do that.  Doesn't apply to the CS-505 config.
  • Custom Op Amps - There are op amps in both the audio and LFO portions of the circuit. Various 4558-family chips were used in the audio portion.  These are common in many, many effects, both classic and modern.  The LFO opamp was a TL022.  Both of these op amps are still readily available and will be used by default.  However, in recent years many other op amps have become available and are often preferred for the various (debated!) tone impacts.  We will continue to use the TL022, or possibly a newer version of it in the LFO unless you strenuously object.  There's no reason for a change there, only bad things can happen.  In the audio portion of the circuit, you can select a different op amp, as long as it is pin-compatible with the 4558 (many opamps are).  The TL072 has gained popularity as a 4558 alternative as it is a little less warm and a little less noisy to some.  The OPA2134 is a high-end audio op amp with an extremely low level of noise.  Those are a couple of examples.  Let us know if you have a preference.  There are a couple that are a bit costly, like the OPA / Burr Brown chips, but most common choices can be subbed in without any additional costs.  The CS-505 config uses TL022 op amps, like the originals.
  • Components - Metal film resistors are used by default to reduce noise.  A mixture of capacitor types is also selected to reduce noise.

 

Front Panel

  • On/Off indicator LED
  • Rate
  • Depth
  • Chorus / Vibrato Switch (not for CS-505)
  • (standard in Bass configuration) Blend
  • (optional) Guitar / Bass - for selecting bass/guitar capacitors
  • (optional) Delay
  • (optional) Standard / Deep Switch
  • (optional) Slow / Fast / Std Speed Switch
  • (optional) Tilt Control

 

Rear Panel

  • Audio In
  • Audio Out
  • On/Off Footswitch
  • On/Off Override
  • DC Power
  • DC Power LED

 

Module Width

  • 1.5" standard
  • 2" with options
  • 2" left wing available for standard (3-4) control configuration
  • 1.5" right wing available for standard (3-4) control configuration

 

Power Consumption (aprox)

45 - 55mA (VibraChorus, VibraChorus Bass)

20 - 25mA (VibraChorus CS-505)

 

Base Configurations

Part # Description List Price
MOD-VCHORUS VibraChorus module $235
MOD-VCHORUS-BASS VibraChorus Bass module $235
MOD-VCHORUS-CS505 VibraChorus CS-505 module $229

 

Options

Part # Description List Price
MOPT-VCHORUS-BBD MN3207 BBD instead of MN3007 $0
MOPT-VCHORUS-BCAP Custom bass capacitor, no switch $0
MOPT-VCHORUS-GBCAPSW Custom bass/guitar capacitors, switched $19
MOPT-VCHORUS-DEEPSW Deep Switch $19
MOPT-VCHORUS-DEEP Deep Mod $0
MOPT-VCHORUS-SPEED Speed Switch $19
MOPT-VCHORUS-DELAY Delay Control $19
MOPT-VCHORUS-CVSW Chorus / Vibrato Switch (included) $0
MOPT-VCHORUS-TILT Tilt Control $19
MOPT-VCHORUS-GATE Noise Gate Threshold Control $19
MOPT-VCHORUS-TRANS Original Transistors $19
MOPT-VCHORUS-DIODES Original Diodes $15
MOPT-VCHORUS-OPAMPS Custom Op Amps $0 - TBD
MOPT-VCHORUS-CC Component Changes TBD