Dayton RS-180s Aluminum Cone Mid-woofer
The Raven is based on Dayton’s 7″ mid-woofer, the RS-180s-8. The “RS” stand for Reference Series while the suffix “s” signifies that the driver is magnetically shielded.
The RS-180s is not for the faint hearted. Many have tried to design a two-way, only to be sorely disappointed by the results. The cone breakup in Fig 1 is often cited as the cause of their failures.
But all is not lost. A superb 2-way can indeed be achieved with the RS-180s. There are challenges along the way but they are not insurmountable.
RS-180s RAW Frequency Response
Fig 2 is the RAW response of the RS-180s when installed in a 13 liters bass reflex box with a baffle width of 8.5″. To avoid room reflections from affecting the measurements, frequencies below 500Hz are Nearfield.
My measurement mimicks that of Dayton’s (see Fig 1). There is a slight rise starting at 500Hz before it starts to roll-off at 2kHz. At 4kHz, the cone breakup starts, culminating with two peaks, one at 7kHz and the other at 9kHz.
Suppressing the Cone Breakup
The Blue plot in Fig 3 is with a 2nd Order Low Pass Filter adjusted to suppress the cone breakup. The two peaks at 7kHz and 9kHz are now reduced by -20dB. This is crucial to the well being of the Raven. If the cone breakup is not reduced significantly, it will interfere with the tweeter, resulting in brittleness in the treble. It is possible to completely eliminate the cone breakup with the addition of a conjugate (LCR) network but since I did not detect any issues on playback, it’s hard to justify the additional cost.
Crossing over to the Peerless XT25TG30-04
The Red plot in Fig 4 is the Peerless XT25TG30 tweeter with a 3rd Order High Pass Filter. Note the RS-180s peaks at 7kHz and 9kHz are down -15dB below the fundamental.
The Raven Frequency Response
The Raven’s response is not as flat as I would like it to be but all things considered, I’m satisfied with it. I found that over the years, my speakers always ended up sounding better when I work with the drivers rather than forcing them to do things they are not comfortable with.
As the response shows, there is a light dip at 2.5kHz. This works to my advantage in that it will tame some recordings where sibilance are a bit “hot”. The gentle curve in the treble, from 3kHz to 9kHz, can be construed as a Low-Q treble boost. This will result in a slight sparkle in the highs.
The Raven in flight
The Raven sounds lively. It is highly responsive. In fact, I would say – fast. The music is immediate.
Mid-range is super clean, second only to the Seas ER18RNX which cost twice as much. The bass is where the RS-180s beats the ER18RNX. It is dynamic, punchy and yet has definition. Equally important, it is loud enough for Full Space, thus doing away with boosting the bass with an electronic equalizer.
Can the Raven be improved upon?
Yes. Replace the Peerless XT25TG30 with a FaitalPro STH100 horn and a Selenium D220ti compression driver. This will elevate the Raven to a whole new level. The cost will obviously be higher but it’s still cheaper than swapping high-end speaker cables.
October 22, 2017Projects