Review on RCF ND850 2" Compression Driver

[Joseph Crowe]

I would like to share my test on the RCF ND850 2" compression driver. The results are pretty good when used as a midrange.

Distortion @85dB SPL 1m, 1kHz...
H2: 0.056%
H3: 0.024%
H4: 0.0072%

Cheers,

Troy J. Crowe

 

[jamescarter1982]

so did you remove the rear chamber then measure from the same side of the driver or spin the driver round and use it as a titanium dome midrange ? if not would it be possible to do this ? would making a larger rear chamber with more absorbant material help keep the distortion nice and low like this .

 

[sunandmoon]

Very interesting, and very low distortion. Where are you thinking of crossing to the woofer? 400Hz?

 

[Joseph Crowe]

so did you remove the rear chamber then measure from the same side of the driver or spin the driver round and use it as a titanium dome midrange ? if not would it be possible to do this ? would making a larger rear chamber with more absorbant material help keep the distortion nice and low like this .

All measurements were done at the front side of the horn. I've done a number of rear chambers and I typically vent them if they are not inside a bass enclosure. The rear cover could be completely open and only serve as a protective guard for the diaphragm. The output from the rear of the driver is typically -9dB down but I do find that it is a welcome addition providing a little bit of spaciousness to the rear and side wall reflections. These reflections arrive so late to the listening chair that there is no harm to clarity. This is specifically for home audio, certainly not for professional sound applications.

 

[Joseph Crowe]

Very interesting, and very low distortion. Where are you thinking of crossing to the woofer? 400Hz?

I settled on a 500Hz crossover. Thanks.

 

[sunandmoon]

All measurements were done at the front side of the horn. I've done a number of rear chambers and I typically vent them if they are not inside a bass enclosure. The rear cover could be completely open and only serve as a protective guard for the diaphragm. The output from the rear of the driver is typically -9dB down but I do find that it is a welcome addition providing a little bit of spaciousness to the rear and side wall reflections. These reflections arrive so late to the listening chair that there is no harm to clarity. This is specifically for home audio, certainly not for professional sound applications.

Yeah, I was curious if having the rear cover removed and giving it a much larger volume would allow for the lower distortion of the open back - the welcome addition providing a little bit of spaciousness - also makes sense. Very cool.

 

[kemmler3D]

Hmm, not bad, in terms of THD and IMD it competes with Purifi mids, even. I would wonder how easy it is to integrate a super-tweeter with a horn in terms of directivity though?