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RE: Roger Modjeski and direct-drive ESL amplifier





Hi Lew,

I plan to use the RM DD amps to drive the Model 3s I acquired. The panels are the same as in your Model 2sw's.

The natural crossover point for the 3's is 200hz it may be lower with the 2sw's . The 18db/ocatave is good; the higher the better so as not to mesh any midrange to the subs at all.

The RM crossover and sub system is 24db/ocatave with variable output for the line array and woofer with set frequency cards that are replaceable in the unit. It is solid state. Given his interest in this and advocacy for it, I would ask him about the crossover in the Bev and Dahlquist to see if there would be a reasonable belief for improvement.

Marchand makes tube crossovers and there is an ARC crossover for sale here on the trader. Bryston makes a very flexible SS crossover as well as Pass .. both are very expensive. The case work and flexibiltiy are expensive in these models.

Regardless, the separate cross over and subs are going to be miles better than the internal woofers and crossovers of the 3's . They should now approach the model 2's.

I like the idea of dealing with RM as he had a hand in working with Bev & is familar with the speakers. He is an avid electrostat proponent so he has perspective which I hope will follow through in his design.

RM suggests the crossover will mate well with the Beveridges as he designed the system for electrostatics. If you read his forum at Audio Circle he is and advocate of outboard crossovers with attenuation for each element of a speaker array with separate amplification. He even will build a 2 or 3way passive crossover into an amp chassis to drive each element of a speaker. I think he is on the right track.



I will run the crossover from my Aesthetix IO with volume controls and 2 supplies. I don't have a transistor bass amp yet .. but I don't think this is overly critical. I will run the line arrays initially with the Futterman and Berning.. then decide on what to do with the DD mono or stereo.

Thanks


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