RCF CD350 1" Compression Driver on ES-800 Biradial

RCF CD350 1" Compression Driver on ES-800 Biradial

In this blog post I test the RCF CD350 1" compression driver. This driver is the ceramic version of the neo ND350 I've used on a variety of past projects. The ceramic version is offered at $90 each, a cost savings of $30 USD against the neo version which can be a big deal to many enthusiasts on a budget. Does the ceramic version offer similar performance? 

With the driver mounted to the ES800 Biradial we get the following frequency response. The driver has no issue loading down to the horn's 800Hz cutoff (Fc). The response is linear with the exception of a -3dB shelf at 3kHz. We see some minor breakup starting to occur at 8kHz deviating (±)1dB in this region. 

The off axis is well behaved which is more a virtue of the horn, but at least indicates good physical match-up at the throat. 

Looking at burst decay, perhaps not the cleanest I've seen, but free of anything too serious. The main breakup mode appears to be just above 15kHz. 


CSD shows some slow decay just above FS but cleans up past 5kHz. Decay is under 0.49ms in the 5kHZ-13kHz region. However I think that the burst decay shown above is a stronger indication of it's time domain performance. 

Harmonic distortion shows -58dB for H2 at 2kHz with H3 and H4 below -68dB. 

Raising the test SPL from 85dB 1m to 95dB 1m sees H2 rise to -50dB with H3 and H4 below -78dB. 

Testing IMD at 85dB 1m we see -70dB performance in the lower midrange improving to -62dB at 10kHz. 


Increasing to 95dB we see IMD worsen in a linear fashion with -50dB showing for 10kHz. This is similar performance to the SB Audience ROSSO 45CDN-PK and the Faital Pro HF108R tested here and the H2606 tested here

Gedlee Metric (Gm) Distortion

Gm for a 75dB test SPL at 1kHz is 0.0100 with THD-A at 0.1164%.

Increasing to 85dB sees Gm increase to 0.0166 with THD-A at 0.2694%

Increasing to 95dB sees Gm increase to 0.0303 with THD-A at 0.7436%.

Comparing the Gm values against the Scanspeak H2606 tested earlier here is shown below. The CD350 is x3.4 higher Gm than the H2606 at both 75dB and 85dB test signal levels. The gap narrows at 95dB where the H2606 is only x1.8 times better than the CD350.

Subjectively I would say that the Scanspeak H2606 with the 2007 horn is better sounding than the CD350/ES800 combo. This correlates with the Gm metric. The H2606 has a slightly more refined and detailed sound. 


The RCF CD350 offers comparable performance to other compression drivers I've tested including the Faital Pro HF108R and RCF ND350. I believe the choice of horn is going to have a larger effect on sound quality than the differences found in these specific compression drivers. 

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