VBS-10.2
Value Buster Series 10" Two Way
VBS-10.2 Peerless/Tymphany DFM-2535R00-08 Version (Obsolete)
Crossover Design:
I wanted to crossover where the woofer and horn directivity would match up, so I was aiming for something in the 1200-1600hz range not yet knowing how the drivers would behave. It ended up working out right in the middle at 1400hz. I was worried this was a tad low for the 1.4" VC compression driver but it doesn't appear to struggle with it at all.
The low pass is 4th order with an LCR notch filter. Highpass is 3rd order on paper but due to the other filters I used to straighten out the response the electrical slope ends up near 4th order as well. Much of the high frequency padding is done in the reactive components of the highpass so very little power is wasted as heat in the resistors padding down the compression driver to match the woofer. This is why the impedance is 12+ ohms over much of the high frequency range though it drops back down at the top end where the sensitivity from the horn/compression driver is the lowest.
The horn has an on axis hole or perhaps better described as a dip between 9-15k which fills in just a little off axis. For this reason I did not want to make on axis response perfectly flat as then there would be high frequency peaking off axis.
Parts List:
C1 (15uF) - C2 (10uF) - C3 (17uF) - C4 (10uF) - C5 (2uF) - C6 (5.1uF) - C7 (15uF)
L1 (3.0mH) - L2 (2.5mH) - L3 (6.0mH) - L4 (2.0mH) - L5 (0.15mH) - L6 (0.20mH)
R1 (15 Ohm) - R2 (3 Ohm) - R3 (7 Ohm) - R4 (5 Ohm)
Woofer (GRS 10PT-8) - Compression Driver (Peerless/Tymphany DFM-2535R00-08) - Horn (Eminence WG-10)
Optional:
PCB kit I've made for this for this crossover/speaker design (will add soon).
Individual driver response, sum and inverted response.
Somehow the dip seen here at 750hz vanished when I tested the speaker again with the finished crossover.
Impedance is 8 Ohm nominal, dipping to a minimum of around 6 Ohms at 20kHz, should be a very easy load for most amps and AVRs.
Measurements taken at 2.83v/2m and scaled up 6dB to approximate 1m level.
Measurements gated at 14ms and blended to diffraction compensated nearfield woofer response below 240hz.
Smoothing applied is 1/48th octave.
On Axis & 10 degrees off axis showing how the top end fills in slightly off axis:
CTA-2034 Style Spin:
Off Axis Horizontal + Normalized to On Axis & 10 Degrees Off Axis,
Directivity tracks extremely well through the crossover and besides the small dip on axis just above 10k the waveguide is very linear as you move off axis.
Horizontal Polar Response - Normal, normalized to on axis & normalized to 10 degrees,
Judging by the normalized polar response I'd put dispersion of the waveguide ~80-85 degrees nominal with some pinching centered near 4k:
Vertical Response Above Axis & Normalized:
Vertical Response Below Axis & Normalized:
Vertical Polar Response - Normal, normalized to on axis & normalized to 10 degrees horizontal,
Ideally stay within +- 10 degrees to stay within +-3dB window:
Harmonic Distortion @ 80, 90 & 100dB/1m - measured at 50cm,
Distortion performance not quite as exceptional in the midrange from the woofer as the 6" VBS-6.2 but nearly as good especially around the crossover. Great performance from the compression driver especially 3rd order which is below 0.1% at 100dB over most of the range through the 2nd harmonic does rise towards the top end but it's still decent and that's out of the critical midband where we are most sensitive to it anyway.
