Active crossover for Martin Logan Prodigy

[Rothenpieler]

Hello Martin Logan Fans,

I'm a proud owner of a Martin Logan Prodigy. I already modified it by activing the bass and using only one high end bass chassis (Audio Technology). The two standard bass drivers caused only trouble - too much bass - in my small room.

Now I consider the option to use also a active crossover (24db) for the tranducer. Does anyone have experience? Since I use a digital preamplifier with room correction I can correct a lot concerning the frequency response, so I don't need a flat frequency responce. I think that makes it easier. Since I have a stable amplifier (Classe) I also can live with low impedancies.

Here are the major questions I have:
- in each of the both parallel applied transformers of the Prodigy 3 cables ar going in: red, brown and black - why 3 instead of 2? Can I connect red and brown when connecting the amplifier to the transformers?
- Do I need a resistor (which value) between transformer and amplifier to avoid a too low impedance?
- Are there other problems which will arise?
- When I apply 24db separation what would be the ideal frequency to separate: 250 HZ?

Your help is appreciated.

Volker Rothenpieler

[Capaciti]

Hi Rothenpieler,

unfortunately its is not very easy to replace the passive cossover by an active filter.

The excisting passive filter is designed with respect to its interaction with the ESL impedance. Those interactions are even used to gain some decibels at certain frequencies.

capaciti

[JonFo]

Hi Rothenpieler,

With active room correction (TacT?) you should be able to overcome deficiencies in the passive crossovers already.

I’d expect the stock setup to deliver reasonable bass after room correction. If not, then you are having Room Correction calibration issues. I’d look into solving those before looking at an active for the Prodigy.

Not than I’m adverse to the idea, I use a DBX DriveRack 260 to do a 3-way active crossover (panel, woofer & sub) on my Monoliths. But then the Monoliths were designed for external crossovers.