Peavey RX14 Compression Driver

Jan 10, 2011

Preliminary Listening Test

Before I decide to conduct any frequency response sweep, it is customary of me to listen to the components first. By simply placing the raw driver beside or on top of a woofer, I can quickly evaluate the sonic qualities of the driver. This saves me a tremendous amount of time and expense. If it doesn't sound right, the component is outright rejected.

The components I'm listening to in this setup is a Peavey RX14 Compression Driver coupled to a 60x40 constant directivity horn. This combo is actually the high frequency section of the Peavey PV115 ( pdf ), a 2-way system with a 15" woofer.

My intention is to determine whether this reasonably priced compression driver with this particular plastic horn is good enough for hi-fi use.

For convenience, the woofer is a Tang Band W5-704s from the Oriole that has the Hi-Vi RT1C-A planar tweeter disconnected. The RX14 and W5-704s are driven by the Synergy, actively crossed at the lowest recommended frequency of 2KHz at 18dB/octave. The Synergy is outstanding in this kind of operation. It's a real chore having to design passive crossovers just to test components. No CD horn equalization, passive or active, has been applied yet.

So, how does it sound. In one word, nice. Doesn't "spit" at me, indicating a smooth response. No excessive sibilance. Surprisingly, tone wise, it is free from the "brightness" that titanium diaphragms are noted for. String instruments like acoustic guitars are rendered beautifully. Definitely worth exploring further. Perhaps, mate it with an 8 inch, one that can extend smoothly beyond 2KHz without nasty cone breakup.


Jan 13, 2011

Impedance Plot

The violet plot is the impedance sweep of the RX14 with the horn attached.

For comparison, a plot of a JBL2425H with a JBL2342 Bi-Radial horn is overlaid.

It's interesting to note that the RX14 plot is almost a flat line, indicating largely a resistive load. In it's expected operating range of 2KHz-10KHz, impedance is close to a constant 8 ohms.


Impedance Sweep (200Hz - 20KHz)

Gated SPL Plot

The violet plot at the top is the raw, unsmoothed, gated spl sweep of the RX14 with the 60x40 horn attached.

On the left, it can be clearly seen it is rolling off at 2KHz.

At 5.5KHz, it rolls of acoustically at 8dB/octave. This is quite expected in a constant-directivity horn.

After a bit of trial and error, a CD EQ network of 1uF with 18 ohms in parallel is the best compromise (green plot).

With my initial crossover at 2KHz, it is apparent that I am right at the knee. Eventhough no audible breakup was detected in listening test, prudence dictates a slightly higher frequency. The Synergy crossover was subsequently re-adjusted for 2.5KHz.

Gated Frequency Response Sweep (1KHz - 20KHz)
Violet Plot - Raw RX14 with horn
Green Plot - RX14+horn+CD EQ

Does it work?

An emphatic YES !!!

The CD EQ (1uF//18 ohms) makes a huge difference. The highs are back on.

At 2.5KHz, the RX14 seamlessly takes over from the woofer. The crossover is totally invisible. Vocals are rendered with the utmost clarity. Crystal clear. No excessive sibilance, no glare in the mid-range.

Now that I've determined the RX14 is indeed an exceptional driver for it's price, the quest is on for an extended range, eight inch woofer.



After much searching, I've narrowed the selection down to a Peerless HDS 830869 and a Hi-Vi F8. Further development will have to wait as a test box needs to be constructed to house the horn and the woofer.

Meanwhile, I'm going to indulge with this combo first. There's nothing like the finesse and realism of a horn.


60 Downes Street | Calais | ME 04619 | USA