Active Bi-Amping Extraordinaire

The Synergy is a High Performance, Active Amplification System specifically designed to achieve the utmost Transparency in 2-way Monitors.

At heart is a precision 18dB/octave electronic crossover that does away with all the ills associated with passive networks.

Unlike conventional crossovers, the Synergy uses 3 DIP Switches instead of multi-ganged potentiometers for frequency selection.

This approach results in an extremely accurate crossover frequency because the entire crossover network now consists of 1% metal film resistors.

Six crossover frequencies ranging from 2 kHz to 4.5 kHz can be selected with these DIP Switches.

But the Synergy is more than just a crossover. It is, in effect, a fully integrated system. It features:

1) Balanced Input

2) Master Volume Adjustment

3) Tweeter Volume Adjustment

4) 18dB/oct 2-way electronic crossover

5) 2 sets of crossover frequencies
    (2K 2K5 3K 3K5 4K 4K5) or
    (1K 1K25 1K5 1K75 2K 2K25)

6) Lm3886TF Overture Power Amp for Tweeter

7) Lm3886TF Overture Power Amp for Woofer

8) 18,800uF of Power Supply Filter Capacitors
    (Rubycon 4,700uF/63V x 4 pcs)

9) +/- 15V Voltage Regulation

Whether you are a recording engineer or an audiophile, if you demand absolute clarity in your playback system, the Synergy is the solution.

Best of all, the Synergy is very easy to build. No discrete circuits. All you need is a soldering iron. No oscilloscope and signal generator are required.




High Precision 18dB/oct Crossover

Six Selectable Crossover Frequencies

Master and Tweeter Volume

Two Lm3886TF Power Amps

+/- 15V Voltage Regulators

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USA only

The Synergy Kit is for one 2-way speaker
Power Heatsink INCLUDED in Kit.
Requires a 20-0-20Vac 200VA Power Transformer
Power Transformer not included


Input Type             Balanced Differential
Input Impedance     20 kohms
Input Protection      RFI Protection

Sensitivity              35 Watts into 8 ohms
Balanced                0.34V rms
Unbalanced             0.68V rms

Crossover             18dB (2-way) State Variable
                            Selectable Frequencies
                            (2K 2K5 3K 3K5 4K 4K5) or
                            (1K 1K25 1K5 1K75 2K 2K25)

Power Amplifers                 LM3886TF x2 pieces
Low Frequency Output          35 Watts into 8 ohms
                                         60 Watts into 4 ohms
High Frequency Output         35Watts into 8 ohms
                                         60 Watts into 4 ohms

Distortion (measured with Boonton 1130)
1) Crossover set at 3K5
2) 35 Watts 8 ohms at Output of Woofer Amplifier

1KHz Sine   = 0.0145% THD+N
100Hz Sine  = 0.0100% THD+N

The Block Diagram above shows the basic building blocks of the Synergy. Before we proceed any further, it is important to highlight that the Synergy is designed to be operated at Line Level. The benefits are two-fold. Firstly, it ensures the lowest noise level. Less gain, less noise. Secondly, it provides the maximum headroom so that the internal stages are not overloaded.

Coming to the operation proper, right at the front is the Balanced Input. RFI protection blocks random radio signals from intruding into the Synergy. For users with Unbalanced Input, it can easily be converted by shorting pin 3 to pin 1.

The next stage is an active Master Volume Control with Unity Gain. This Volume Pot controls the internal signal level of the Synergy.

The third stage is a 2-way, 18dB/octave, State Variable crossover that divides the frequencies to the tweeter and the woofer. Users can select any one of the six, precision Crossover Frequencies via 3 DIP switches. Standard frequencies are 2K 2K5 3K 3K5 4K 4K5. Another set of frequencies, at half the range, is possible by simply doubling the filter network capacitors.

The High Pass Output of the crossover is supported by an active Tweeter Volume Control. This stage has a Gain of 3x. The tweeter signal is finally met by a LM3668TF power amplifier.

The Low Pass Output has a unity gain inverter inserted between it and the power amplifier. Apart from maintaining absolute phase, it also acts as a buffer to preserve signal integrity.

High Resolution Oscilloscope Captures
Synergy at following settings
Crossover = 2 kHz
Master Volume = Gain 1x
Tweeter Volume = Gain 3x

Fig 1 (5mV/DIV)
Crossover High Pass Out
Measured at "A" in Block Diagram

Fig 2 (10mV/DIV)
Tweeter Power Amp Out
Lm3886TF Gain=22x

Fig 3 (5mV/DIV)
Crossover Low Pass Out
Measured at "B" in Block Diagram

Fig 4 (5mV/DIV)
Woofer Power Amp Out
Lm3886TF Gain=22x

60 Downes Street, Calais, ME 04619, USA