S19 dipole radiator - outdoor measurements
Coverage of dipole loudspeaker frequency response can be improved by using a small midrange driver from 400hz to 2khz. My previous attempt of building dipoles used the venerable Seas Excel W22 and I felt they were pushed to high. The tradeoff of 4-way dipoles are complexity and more difficult design process to take account of polar response changes. I have investigated few 5" midrange drivers: Fountek FW146, Vifa P13WH, and Seas Excel W15CH001 and all perform better as each only need to reproduce 2 octaves.
Please follow the build progress at HTGuide Forum.
Specifications
Topology: Active 4-way
Radiation pattern: Dipole
Directivity: Dipole from 20hz - 2khz transitioning to dipolar to 20khz
Frequency response: 20hz - 20khz. LFE Q of 0.707
Sensititivity: ~88dB
Dimension (H, W, D): 120 x 29 x 33 (cm)
Amplifiers: 8-Channels required (2x stereo amps)
Crossover: DSP, 2x (MiniDSP + 2way Advanced Plugin)
Directivity Pattern
Indoor measurements, normalised to 0 deg:
Both are normalised to inspect carefully the directivity aspect. Clearly we see the acoustically small midrange started to bloom as well as the loss of small horn's directivity. Yet it is quite acceptable with 10deg shift through 1khz-2.5khz region. It then transition smoothly to forward radiating.
... to be continued
Update 12/3/12
Outdoor measurements to investigate the frequency response of midrange.
Update 25/3/12
Seas Excel W15CH001 received and tested
Update 2/4/12
First prototype of S19M (magnesium)
Seas Excel W22E001
Seas Excel W15CH001
S19/MT - Titanium dome Tweeters (Vifa DQ25) used for improved resolution.
5 comments:
Why not reduce the baffle size going upwards, like in the Note? Is this not a relatively drawback-free approach to keeping the dipole pattern up high?
Changing baffle width would indeed provide better off-axis response. I am not a fan of the looks though. The 5" driver on 29cm baffle is not too bad.
Would love to hear these one day.
What kind of tweeter and matching horn was used for the S19?
Tweeters are Vifa XT25, waveguides are Monacor WG300
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