S19 4-Way Dipole Radiator


S19 dipole-radiating speakers

The quality of dipole loudspeaker accuracy is improved by using a small 5" midrange driver from 400hz to 2khz. The tradeoffs are higher complexity and more difficult design process to take account of polar response changes.


Push-pull dipole subwoofer section

The dipole subwoofers are w-frame to benefit from vibration cancellation. They are long-throw Dayton RSS256HF-8. The woofers are Seas Excel W22EX001 and W15CH001, and the Tweeters are Seas DXT.

The w-frame sub's cancellation topology really works. It's quite mesmerising to see the drivers pumping air furiously yet there is no cabinet vibrations. Seen below is how clean they are crossed at 120hz. The subs are -3db at 20hz.



Please follow the build progress at HTGuide Forum.

Specifications
Topology: Active 4-way
Radiation pattern: Dipole
Directivity: Dipole from 20hz - 2khz then forward-directional
Frequency response: 20hz - 20khz.
Sensititivity: ~88dB
Dimension (H, W, D): 117 x 31 x 31 (cm)
Amplifiers: 8-Channels required (4x stereo amps)
Crossover: Two 2x4 MiniDSP


Update 12/3/12
Outdoor measurements of early prototype to investigate the frequency response of small midrange.










Update 25/3/12 - Seas Excel W15CH001 received and tested
Update 2/4/12 - First prototype of S19M (magnesium)
Update 20/4/12 - S19/MT - Titanium dome Tweeters (Vifa DQ25) used for improved resolution.
Update 31/8/12 - Started the final design of the cabinet and wood choices
Update 2/9/12 - Cabinets completed
Update 23/1/13 -  I have been living for quite a while with these speakers. I havent' had any desires to build something new !
Update 28/6/13 - Frequency response in the critical 1khz-20khz region showing ±1db (XT25)









Update 13/9/13 - The 4x Dayton Reference subs requires large power to drive them to xmax.



19 comments:

Anonymous said...

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?

gainphile said...

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.

Drizt said...

Would love to hear these one day.

Alex said...

What kind of tweeter and matching horn was used for the S19?

gainphile said...

Tweeters are Vifa XT25, waveguides are Monacor WG300

einis said...

is the addition of the 5" absolutely needed?
the 8" seas in a 3-way is good enough for Siegfried Linkwitz :)

Paul said...

Hi Andy,

Looks great. Are you going to offer plans & a mini dsp config file (like your S15's) ?

gainphile said...

Hi Einis, the addition of 5" midrange has two benefits: 1) Relieve the stress and distortions of 8" woofers and tweeters, and 2) ability to cross over at higher frequency which eliminates the need for rear tweeters.

gainphile said...

Hi Paul, yes as soon as I have a blue sky with no wind for outdoor measurements.

Anonymous said...

How do you like the SEAS DXT compared to the Vifa DQ or XT?

Anonymous said...

Hi Andy,

I have a set of Scanspeak Illuminator drivers (tweeters, 12cm midrange and 18cm mid bass) that was suposed t be used for a close box project, but now that I came across your website I would like to try one of your OB projects.
Do you think that the SS Illuminators would be fine in an OB? I was thinking of something like the S19 or the S9 + dipole subs..
Thanks in advance for your help
roberto

gainphile said...

Yes I think the Illuminators would make a great set of dipole speakers. As usual you have to take it outside for best measurement result and equalise accordingly. Note that 12cm drivers are smaller than my W15 which would be a directivity compromise.

Bevan Dewar said...

Hi mate, I like the idea of the vibration cancelling aspect of your bass drivers, could you tell me how you calculate the cavity resonance for these kinds of configuration? I'm wanting to use two 12" driver to run to 200hz and wondering how deep I can make the cabinets. Thanks,
B

Christopher Miller said...

gainphile,
I'm also interested how you like the DXT tweeter compared to the XT tweeter [in waveguide].

gainphile said...

Hi Bevan, the cavity resonance is a quarterwave ie. speed of sound divided by cavity depth. So for 30cm deep cavity the resonance is approx (344/0.3)/4 = 288hz

gainphile said...

Hi Christopher, I like the resolution of DXT tweeter, but love the silky smoothness of XT25. I had been listening to XT25 mostly for the past 6 months or so.

Unknown said...

Absolutely gorgeous speakers! Do you intend to offer plans for sale? I would be very interested.
Steve
Hardrockcorp@gmail.com

gainphile said...

Hi Steve, thanks for your appreciation. These are for hobby only so I don't sell plans but of course you can simply copy it. Hope to document them soon (no promises!)

Роман Плотников said...

Gainphile,
You have some amazing experience of testing out various designs. Do you plan to eventually move beyond S19 (judging by the 'currently listening ' on the top of the blog page)?
If no, what made you chose OB design over econowaves?
If yes, what is your opinion on unity/synergy horns?