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Active Crossover Module
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2 way Active Crossover Module (ACM)
Here we have the inards of the Reveille Active Crossover that we previously designed for use with the Oris Horn
system. However this module possesses a few extra capabilities that make it usable for most other two-way crossover applications intended for bi-amping.
The ACM is a dual mono design with two independent channels on one circuit board.
The High Pass Section:
The high pass section contains no active circuitry. You can run the full signal straight through to the high pass amplifier or we have included the
option of using a single series in-line capacitor to create a passive 1st order (6dB/octave) high pass filter on the input of your high pass amplifier.
Using this capacitor is a trade-off. Yes, you are adding another capacitor to the signal path, but then using this cap to roll off the low frequencies
going to the high pass amplifier may make a noticeable improvement in the midrange clarity. The choice is yours.
The Low Pass Section:
The low pass section contains one gain stage, two filter sections using high speed Burr Brown buffers, a level control for matching the high and low
pass gain, and finally a high speed -- high current Burr Brown buffer for the output stage. A potentiometer is included in the low pass section to
help match the gains of the low and high pass sections.
I chose a solid-state circuit design over tubes for several reasons however the main driving force was
linearity, low noise and good current drive. My philosophy has always been to start with as clean a signal as possible and then tailor as needed from
there. Solid state circuits are ultra-quiet, and if designed properly can provide a very natural sound with great resolution, detail and pitch-black
backgrounds. This Active Crossover Module won’t get in the way of the music.
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| Active Crossover Schematic |
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As mentioned above, we have "built-in" some added versatility for those of you choosing to use the crossover in various applications, i.e. a bi-amp
system with a straight-thru high pass section. A good example would be; using the crossover in a mini-monitor/subwoofer arrangement. Thus, the
crossover’s low pass section can be configured as a 1st, 2nd, 3rd or 4th order filter (i.e. 6, 12, 18 or 24dB/octave). We have also laid out the
crossover circuit board to accept different size capacitors in order to aid your component selection. Our assembly manual provides the equations and
guidance to help you choose the right values for your filter or you can tell us your crossover frequency and we will calculate the appropriate values
for you. Note: the nature of this design limits the crossover frequency to no higher than 500Hz.
As with all Welborne Labs kits, high quality components are used throughout design. |
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Power Supply Selection
Our Active Crossover Module is completely dual mono and each channel has its own onboard voltage regulators, therefore we suggest you use a dual
mono power supply like our PS5. The PS5 is a great low noise supply featuring toroidal power transformers that are isolated from the rest of the
circuitry providing the necessary shielding for the crossover circuit as well as adjacent audio equipment. Below is a picture of the Active
Crossover Module connected to the PS5 supply.
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The Active Crossover Module requires a minimum power supply input of +/- 18Vdc @ 300mA. Maximum input voltage is 34Vdc.
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Active Crossover Module Pricing
The ACM is available in a Basic and Ultimate version. The Basic version includes 1% Dale metal film
resistors, Wima film capacitors, NS voltage regulators, Nichicon low impedance electrolytics and Cardas capacitors for the high pass capacitor.
The Ultimate version upgrades the voltage regulators to Linear Technology and the electrolytics to Elna Cerafines.
For a 1st or 2nd order low pass filter order the ACM1. For a 3rd or 4th order low
pass filter order the ACM2. On our shopping cart checkout page there is "comments" box where you can tell us the crossover frequency you desire.
Or you can email us your request.
Of course we highly recommend that you order one of our PS5 dual mono power supplies to
power the crossover.
We also offer a complete kit, less chassis, which is basically a nude version of our
old Reveille Active crossover kit. The complete kit includes everything required to build an Ultimate version 2-way crossover minus a chassis.
Includes ACM, PS5 power supply, power switch, fuse, IEC connector and power cord. The kit also includes Vampire rca jacks, teflon coated OFC
wiring and detailed assembly instructions.
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ACM1A |
Basic Version 1st or 2nd Order w/Cardas Cap |
$110.00 |
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ACM1B |
Ultimate Version 1st or 2nd Order w/Cardas Cap |
$138.00 |
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ACM2A |
Basic Version 3rd or 4th Order w/Cardas Cap |
$120.00 |
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ACM2B |
Ultimate Version 3rd or 4th Order w/Cardas Cap |
$148.00 |
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PS5 |
PS5 Dual Mono Power Supply |
$162.00 |
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ACKIT |
Complete Xover Kit 1st,2nd,3rd or 4th order |
$395.00 |
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