VCL EX23

4-way speaker with the Scanspeak Ellipticor 15” woofer and 8” lo-midrange, the new Bliesma 3” dome hi-midrange and the Viawave ribbon tweeter

This is a 4-way speaker concept using recently developed transducers. Measurements and reviews of these drivers look very promising to realize a very good sounding loudspeaker.
The transducers are the 15 inch Scanspeak Ellipticor 38WE8582T00 as woofer, the 8 inch Scanspeak Ellipticor 21WE8542T00 as lo-midrange, the new 3 inch dome Bliesma M74B-6 as hi-midrange and the Viawave SRT-7 ribbon tweeter.
The speaker cabinet is a tower of 109 cm high, 45 cm wide and 50 cm deep. The netto internal volume is 145 L and the woofer and lo-midrange speaker system are closed box, the woofer in 125 L and the lo-midrange in 20 L.
The midranges and the tweeter are placed horizontal asymmetric on the front baffle to improve the SPL on axis and the DI index responses of the transducers mounted in the cabinet.
The speaker sensitivity is 90 dB at 1m, 2.83 V_rms, full space.
The low frequency response F3 = 50 Hz, F6 = 38 Hz and F12 = 26 Hz.
For a woofer maximum excursion condition at 50 Hz the speaker maximum SPL is 111 dB @ 50 – 20000 kHz at 1m, free space.
A digital crossover filter will be designed, it can be used for the first listening tests.
Using the voltage transfers of the final digital filter a 4-way analog active filter with opamps or tubes can be designed.
Also a 4-way passive filter can be an option. It will become rather extensive but possible.

Specificaton Headlines

System: 4-way, woofer and lo-midrange closed box system, analog X-over
Woofer: Scanspeak Ellipticor 38WE8582T00
Lo-midrange: Scanspeak Ellipticor 21WE8542T00
Hi-midrange: Bliesma M74B-6
Tweeter: Viawave SRT-7
Low frequency response: F3 = 50 Hz, F6 = 38 Hz and F12 = 26 Hz
Sensitivity: 90 dB at 1m, 2.83 V_rms, full space
SPL at maximum excursion, 50 – 20000 Hz: 111 dB, 1m, full space
Crossover: LR4 200, 800 and 3200 Hz
Cabinet dimensions: width x heigth x depth = 45 cm x 109 cm x 50 cm

Estimation Bill Of Material

2 x Woofer : Scanspeak Ellipticor 38WE8582T00: 3100 euro
2 x Lo-midrange: Scanspeak Ellipticor 21WE8542T00: 1840 euro
2 x Hi-midrange : Bliesma M74B-6: 1290 euro
2 x Tweeter: Viawave SRT-7: 503 euro
Components high quality crossover: 1500 euro
Components medium quality crossover: 1000 euro
Cabinet material: 200 euro
Cabinet Accessoires: 100 euro
Total without crossover filter or amplifiers for the digital version: 7033 euro
Total with high quality passive crossover 8533 euro
Total with digital filter and amplifiers tbd

Speaker system

Cabinet

Cabinet dimensions

SPL and impedance curves of the transducers in the cabinet

These are the SPL and impedance curves of the transducers placed in the cabinet in free space at 3 meter, 2.83 V_rms . Also the SPL responses on infinite baffle are shown to see the impact of the cabinet shape on the response.
These simulated curves are used for a first crossover filter design.

SPL woofer in the cabinet on-axis in free space (blue curve) and on infinite baffle (pink curve)

Impedance woofer in the cabinet

SPL lo – midrange in the cabinet on-axis in free space (brown curve) and on infinite baffle (pink curve)

Impedance lo – midrange in the cabinet

SPL hi – midrange in the cabinet on-axis in free space (green curve) and on infinite baffle (pink curve)

Impedance hi – midrange in the cabinet

SPL tweeter in the cabinet on-axis in free space (red curve) and on infinite baffle (pink curve)

Impedance tweeter in the cabinet

Polar diagrams

Horizontal polar diagram woofer in cabinet free space at 80 – 160 – 320 – 640 – 1200 Hz

Vertical polar diagram woofer in cabinet free space at 80 – 160 – 320 – 640 – 1200 Hz

Horizontal polar diagram lo – midrange in cabinet free space at 80 – 160 – 320 – 640 – 1200 Hz

Vertical polar diagram lo – midrange in cabinet free space at 80 – 160 – 320 – 640 – 1200 Hz

Horizontal polar diagram hi – midrange in cabinet free space at 0.64 – 1.2 – 2.5 – 3.8 – 5.1 kHz

Vertical polar diagram hi – midrange in cabinet free space at 0.64 – 1.2 – 2.5 – 3.8 – 5.1 – 6.4 kHz

Horizontal polar diagram tweeter in cabinet free space at 2.5 – 3.8 – 5.1 – 6.4 – 12 kHz

Vertical polar diagram tweeter in cabinet free space at 2.5 – 3.8 – 5.1 – 6.4 – 12 kHz

Off axis response, Power and Directivity Index of the transducers in the cabinet

To calculate the power response and directivity index, the horizontal and vertical SPL off axis responses of the woofer, the midrange and the tweeter are simulated in steps of 15 degrees, the speaker placed in a full sphere at 3m distance. The power is calculated out of the mean value of these curves. The power is represented as the SPL of an omnidirectional source at 3m distance in a full sphere with a SPL value equal to the power.

Woofer

Horizontal SPL on and off axis of the woofer in the cabinet at 0, 30, 45, 60, 75 and 90 degrees

Vertical SPL on and off axis of the woofer in the cabinet at 0, 30, 45, 60, 75 and 90 degrees

SPL on axis and Power of the woofer in the cabinet in a full sphere

SPL on axis in black and the power in blue

Directivity Index DI in a full sphere of the woofer in the cabinet

Lo – midrange

Horizontal SPL on and off axis of the lo – midrange in the cabinet at 0, 30, 45, 60, 75 and 90 degrees

Vertical SPL on and off axis of the lo – midrange in the cabinet at 0, 30, 45, 60, 75 and 90 degrees

SPL on axis and Power of the lo – midrange in the cabinet in a full sphere

SPL on axis in black and the power in brown

Directivity Index DI in a full sphere of the lo – midrange in the cabinet

Hi – Midrange

Horizontal SPL on and off axis of the hi – midrange in the cabinet at 0, 30, 45, 60, 75 and 90 degrees

Vertical SPL on and off axis of the hi – midrange in the cabinet at 0, 30, 45, 60, 75 and 90 degrees

SPL on axis and Power of the hi – midrange in the cabinet in a full sphere

SPL on axis in black and the power in green

Directivity Index DI in a full sphere of the hi – midrange in the cabinet

Tweeter

Horizontal SPL on and off axis of the tweeter in the cabinet at 0, 30, 45, 60, 75 and 90 degrees

Vertical SPL on and off axis of the tweeter in the cabinet at 0, 30, 45, 60, 75 and 90 degrees

SPL on axis and Power of the tweeter in the cabinet in a full sphere

SPL on axis in black and the power in red

Directivity Index DI in a full sphere of the tweeter in the cabinet

All transducers

Directivity Index DI in a full sphere of the woofer, lo – midrange, hi – midrange and tweeter in the cabinet

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