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B&C DCM50 16ohm or 8ohm for Type A crossover


Welborne

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Hi guys,

New here. Have been tweaking my La Scala the last few months. Bought soldered lig version K55v, replaced the mid horn with Azura Le Cleac'h flare round, tweeter replaced by B&C DE120 with a cheap PRV tractrix waveguide (us$8 each on Parts Express). I made a new Type A crossover using russian K75-10 pio capacitors.

I am curious about a better mid driver, and have been thinking about the B&C DCM50. My listening space isn't very big, neither do I listen to very loud volume in most instances, so I guess the DCM50 should still be ok, although I may make another crossover similar to AlK's Universal or John Albright's DHAX2. My question is: should I get the 16ohm or 8ohm version? For example, in the Universal there is a 10ohm resistor across the autoformer which I think is to flatten the 16ohm (of k55) to something around 8ohm, and this necessitates a change of high pass capacitance from Type A's 13uf to 48uf. So If I get a 8ohm DCM50, the 48uf would not be correct and need to be adjusted.

I am hoping someone can throw a torch here.

Thanks

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Guest David H

The type A really doesn't work for the DCM-50, the sensitivity is too high, and the type A doesn't have a band pass on the mid range.

 

An ALK type crossover will work fine, and I would go with the DCM-50 16 ohm version.

 

Welcome to the forums, enjoy.

 

 

Dave

Edited by GotHover
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Guest David H
For example, in the Universal there is a 10ohm resistor across the autoformer which I think is to flatten the 16ohm (of k55) to something around 8ohm, and this necessitates a change of high pass capacitance from Type A's 13uf to 48uf. So If I get a 8ohm DCM50, the 48uf would not be correct and need to be adjusted.

 

With the universal crossover you can use either the 8 ohm or the 16 ohm. The 10 ohm swamping resistor keeps the impedance around 8 ohms regardless of attenuation level. 

 

The DCM-50 is a great choice.

 

Dave

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You just can't drop to another tap. You also have to scale down the primary capacitor value because of the higher impedance (it changes based the tap you choose), add a coil in between the decided upon output tap and squawker positive (in order to form a band pass filter), and then move the tweeter connection from tap 5 to input positive -- it's almost like building a new filter. You need better capacitors too -- especially when the driver becomes that revealing.

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