Active sub crossover class A
• active lowpass subfilter
• balanced mono output
• decoupled channel summation
• zero stereo impairment
• Filter Class A with JFet cascade
• separate signal (0) and shield mass (S)
• Level and frequency via switches
• zero potentiometer, hum, noise
• sub driver: 100 x 58 mm, high 12 mm
• sub driver 58€buy
Crossover with supply
• sub driver - supply: 100 x 100 mm, high 40mm
• sub driver - supply class A 98€buy
Crossover with supply and trafo
• sub driver - supply - trafo: 100 x 175mm, high 40mm
• sub driver - supply class A - trafo 138€buy
PCB without components
• Board without components: 100 x 175 x 1,6 mm
• Board, heat sink, circuit diagram 24€buy
The heat sink is included, all other components are freely available.
The board is suitable for transformers of Talema type 70063K (25VA) or 70040K (10VA).
Maximum flexibility is provided by separating the corresponding areas.
With separation of the active crossover you get e.g. the High-End Class A power supply for preamplifiers.
The sub driver generates the analog deep bass signal for the subsequent amplification from the stereo input.
Correction and pre-filtering are done without gimmicks.
The limit frequency, which is designed for a reasonable range, and the level for adaptation to the satellites are set.
We do not use inequalities, scattering or inhibiting layers of coal from Pots.
Two phase-shifted signals are available at the output.
An existing stereo amplifier can be used symmetrically - each stereo channel receives one signal, the speaker is then connected to both "plus poles" L + R.
Prerequisite: The stereo power amplifier has no capacitors in the signal at the output.
Any mono amplifiers are operated at one of the two outputs if they do not have a balanced XLR input.
The experimental setup shows the sub driver in a balanced arrangement with two SAC amplifiers.
Since the transformer for the output stages (not in the picture) also supplies a reduced auxiliary voltage, the sub driver with Class A power supply was chosen here but without its own transformer.
The class A voltages are looped to the side in the sub driver in order to be able to connect further pre-stage components.
SAC amplifiers for the drive of the satellites remove low-frequency loads by changing only one capacitor without additional active crossover.