Boa Constrictor
Classic vintage compressors with all the options
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The Boa Constrictor compressor rack effect modules compares to two of the most famous vintage compressors - the Ross Compressor and the MXR Dynacomp. Those two compressors and their many, many derivatives are very similar, but offer a wide array of possibilities for customization.
Description
The Ross Compressor has been one of the most popular compressors of all time. Vintage units are commanding high prices, which seem to be climbing steadily. The MXR Dyna Comp is also a very popular compressor. Both compressors have minimal controls, enabling them to function simply and easily. But there are numerous options that can provide a much wider range of control of these compressors, resulting in considerably more flexibility in function and tone. The Boa Constrictor offers a wide range of these options, which can tailor the circuit to the needs of players that are well-versed in compressors and what they do and find the original pedals too limited in range.
We offer multiple base configurations of the Boa Constrictor. These configurations represent sets of modifications that go together and would be tedious to configure separately. Most of the numerous options we offer will work with all the configurations, but check the compatibility notes to be sure. Some of the options do similar things in different ways - you may need some in-depth knowledge of Ross Compressors to decide which one might best suit your needs. Due to the large number of options, there are many, many possible versions of the circuit that can be built. We cannot test all those combinations. It's not that we are concerned the options won't work, but we do expect that there are combinations that will overlap in their function, negating each other or yielding odd ranges of functionality. So while it may be tempting to configure a module with lots of options to give great control, we recommend that only a few options specific to your needs be chosen, avoiding multiple options that perform similar functions.
The base configurations are built around a couple of choices. The MXR Dyna Comp and Ross Compressor are often considered two reasonably different compressors. However, their circuits are actually very similar. Some of our options let you choose to make the circuit more like one or the other of those two compressors, or even have a switch to switch between them. The other choice to make is whether you want to use components that are more similar to the original pedals, or more modern components that are technically equivalent or better, particularly in terms of noise. Since noise can be a factor, we tend to prefer quieter components.
Popular versions of the Ross and Dyna Comp compressors are available, including the Keeley Compressor, Analogman Comprossor, Way Huge Saffron Squeeze, and many others. We don't offer specific sets of options that are the same as those compressors, but you can choose from our options to provide the same types of controls and modifications offered in a variety of compressor pedals.
Configurations
| Option/Feature | Vintage Ross | Modern Ross | Vintage Dyna | Modern Dyna | Vintage Dyna/Ross | Modern Dyna/Ross |
| Standard Controls | Sustain, Level | Sustain, Level | Sensitivity, Output | Sensitivity, Output | Sustain, Level | Sustain, Level |
| Default Transistors | 2SC1849 | 2N3904 | MPS5172, 2SC1849 | 2N3904 | 2SC1849 | 2N3904 |
| Default Op Amps | CA3080A | CA3080E | CA3080A | CA3080E | CA3080A | CA3080E |
| Dyna/Ross Switch | n/a | n/a | n/a | n/a | included | included |
| Noise Cap | 220pF | 150pF | none | 150pF | none / 220pF | 150pF |
| Noise Cap Switch | option | option | option | option | included | option |
| Clipping Control | option | option | option | option | option | option |
| Attack Control | option | option | option | option | option | option |
| Attack Range Switch | option, requires Attack Control | option, requires Attack Control | option, requires Attack Control | option, requires Attack Control | option, requires Attack Control | option, requires Attack Control |
| Tone Control | option | option | option | option | option | option |
| Mix Control | option | option | option | option | option | option |
| JangleBox Switch | option | option | option | option | option | option |
| Bright Switch | option | option | option | option | option | option |
| Voltage | 9V standard | 15V standard | 9V standard | 15V standard | 9V standard | 15V standard |
| Voltage Switch | option | option | option | option | option | option |
| Output Buffer Switch | option | option | option | option | option | option |
Options
- Custom Transistors - Switch to a different transistor type, perhaps MPSA18, 2N5089, 2N5088, or 2N2222.
- Custom Op Amp - Switch to a different op amp, the BA6110 is a quieter alternative to the CA3080. CA3080A, CA3080E, and BA6110 are the only pin-compatible op-amps we normally stock.
- Custom Noise Capacitor - Switch to a different noise capacito size. Noise caps send frequencies above their cutoff point to ground. A lower value for the capacitor allows more highs (and usually more hiss) into the effect. A higher value cuts out more highs and more noise. A value of 0 cuts nothing, allowing all highs and noise into the circuit. For guitar, 470 or more will start removing a noticeable amount of highs. For bass-only use, a higher value up to 1000pF may be OK. Ideally, there wouldn't be a noise cap and all your signal would go through. But compressors will highlight high-frequency noise, so there's usually a trade-off that must be made between less noise and more highs.
- Noise Cap Switch - Add a switch that will switch between two values for the noise cap.
- Clipping Control - Add an input cut that allows you to trim down hot inputs that might cause clipping or distortion
- Attack Control - Add a control to allow the attack time to be increased or decreased. The standard Attack speed is in the noon position for this control.
- Attack Range Switch - Add a switch that gives the Attack Control two ranges of values that have a small overlap. One switch setting will provide a range of faster than normal values. The other setting goes from slightly faster than normal to slower settings. The standard attack speed will be just before center, around 11 o'clock, on the second setting. This just gives a broader range of possible Attack settings. This option requires the Attack Control option.
- Tone Control - Add a Tone control. This is not a normal Tone control. It allows some accentuation of highs, which often seen to be trimmed in this circuit and by compressors in general. Maybe wouldn't mix this with the JangleBox or Bright mods, but it is technically possible.
- Mix Control - Add control to adjust the ratio of wet and dry signal
- JangleBox Switch - Add a switch that will boost the highs to provide more jangle in your tone. One position on the switch will be the standard level of highs. The second position will have the jangle highs. If you want, we can add a third position for super jangle highs. Maybe wouldn't mix this with the Tone Control or Bright mods, but it is technically possible.
- Bright Switch - There is a bit of high/noise filtering near the output of the circuit. This mod adds a switch that allows more of the highs (and potentially noise) to pass thru and to the output.
- Custom Voltage - Higher voltages will generally improve the sound of the circuit by reducing clipping and distortion. This may be especially true for basses and guitars with high-output or active pickups. We use the standard 9V by default for the vintage configurations, but running them at 12V or 15V is probably better if you want cleaner output. If you utilize some clipping/distortion caused by overloading the circuit at 9V, then you may want to stick with 9V.
- Voltage Switch - Normally we don't recommend having switchable voltages, but since the circuit is somewhat sensitive to voltage you might want to do this. What we would generally recommend is using 15V without a switch, but it is your choice.
- Output Buffer - Some players may have experienced impedance problems with pedals that come after Ross compressors. In those cases, placing a buffer after the compressor solves the problem. Of course, you can always do that with one of our buffer modules. This option adds an always on output buffer in the Boa Constrictor module. It becomes a twofer module, if you need it.
- Output Buffer Switch - Same as the Output Buffer option, but the new buffer can be use/bypassed with a front panel switch.
- Custom 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
- Sustain/Sensitivity - labels are different for Ross vs Dyna configurations
- Level/Output - labels are different for Ross vs Dyna configurations
- (standard in Dyna/Ross configs) Dyna/Ross Switch
- (optional) Noise switch
- (optional) Clipping
- (optional) Attack
- (optional) Attack Range switch
- (optional) Tone
- (optional) Mix
- (optional) Jangle switch
- (optional) Bright switch
- (optional) Volts switch
- (optional) Buffer switch
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, possibly 3"
- 2" left wing available for standard (3-4) control configuration
- 1.5" right wing available for standard (3-4) control configuration
Power Consumption (aprox)
15 - 45mA
Base Configurations
| Part # | Description | List Price |
| MOD-BOA-VR | Boa Constrictor Vintage Ross module | $214 |
| MOD-BOA-MR | Boa Constrictor Modern Ross module | $214 |
| MOD-BOA-VD | Boa Constrictor Vintrage Dyna module | $214 |
| MOD-BOA-MD | Boa Constrictor Modern Dyna module | $214 |
| MOD-BOA-VDR | Boa Constrictor Vintage Dyna/Ross module | $219 |
| MOD-BOA-MDR | Boa Constrictor Modern Dyna/Ross module | $219 |
Options
| Part # | Description | List Price |
| MOPT-BOA-TRANS | Custom Transistors | $0-TBD |
| MOPT-BOA-OPAMP | Custom Op Amp | $0-TBD |
| MOPT-BOA-NCAP | Custom Noise Capacitor | $0 |
| MOPT-BOA-NCAPSW | Noise Capacitor Switch | $19 |
| MOPT-BOA-CLIP | Clipping Control | $19 |
| MOPT-BOA-ATK | Attack Control | $19 |
| MOPT-BOA-ATKSW | Attack Range Switch | $19 |
| MOPT-BOA-TONE | Tone Control | $19 |
| MOPT-BOA-MIX | Mix Control | $29 |
| MOPT-BOA-JBSW | JangleBox Switch | $19 |
| MOPT-BOA-BSW | Bright Switch | $19 |
| MOPT-BOA-VOLT | Custom Voltage | $0 |
| MOPT-BOA-VOLTSW | Voltage Switch | $45 |
| MOPT-BOA-BUF | Output Buffer | $45 |
| MOPT-BOA-BUFSW | Output Buffer Switched | $55 |
| MOPT-BOA-CC | Custom Components | TBD |