Hi!
This will be my second project using a waveguide created with ATH4
https://www.diyaudio.com/community/threads/acoustic-horn-design-the-easy-way-ath4.338806/
My first project is here
https://www.diyaudio.com/community/threads/hf10ak-12p80nd-custom-wg.360973/
Those speakers have been used to good reception at my local church for charity "cinema" nights. They have now ended up forming the speakers of a Hauptwerk based organ. Sadly the 1960s pipe organ is beyond economical repair.
The new design continues the use of the same parts with a slight tweak to the waveguide depth to align the acoustic depths of the HF10AK and the 12P80ND measured during the development of the above speaker.
I hope to manufacture them in such a way they will look like the attached. Dimensions and driver positions not set in stone.
Parts
1x HF10AK + custom waveguide
1x 12P80NDv2 rear ported exponential aperiodic
2x 18H500 in a 7cuft3 sealed box
custom active opamp crossover
Neurochrome "Done Right" amps
More to follow.
This will be my second project using a waveguide created with ATH4
https://www.diyaudio.com/community/threads/acoustic-horn-design-the-easy-way-ath4.338806/
My first project is here
https://www.diyaudio.com/community/threads/hf10ak-12p80nd-custom-wg.360973/
Those speakers have been used to good reception at my local church for charity "cinema" nights. They have now ended up forming the speakers of a Hauptwerk based organ. Sadly the 1960s pipe organ is beyond economical repair.
The new design continues the use of the same parts with a slight tweak to the waveguide depth to align the acoustic depths of the HF10AK and the 12P80ND measured during the development of the above speaker.
I hope to manufacture them in such a way they will look like the attached. Dimensions and driver positions not set in stone.
Parts
1x HF10AK + custom waveguide
1x 12P80NDv2 rear ported exponential aperiodic
2x 18H500 in a 7cuft3 sealed box
custom active opamp crossover
Neurochrome "Done Right" amps
More to follow.
Attachments
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@LineSource data for dual "counter-force" 18FH500 https://www.diyaudio.com/community/...i-speakers-eighteensound.285652/#post-4592831
"Two Faital 18FH500 woofers producing 100db SPL with -3db at 20Hz Linkwitz Transform
Box Volume = 7cuft____Qtc=0.76___Power for 100db SPL @ 30Hz = 15.5watts"
"Two Faital 18FH500 woofers producing 100db SPL with -3db at 20Hz Linkwitz Transform
Box Volume = 7cuft____Qtc=0.76___Power for 100db SPL @ 30Hz = 15.5watts"
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I look forward to simulating point 3) that @LineSource makes here too https://www.diyaudio.com/community/threads/2-way-diy-hifi-speakers-eighteensound.285652/post-4597436 and investigating how the edge radius and distances affect directivity. @mabat is making strides here https://www.diyaudio.com/community/threads/acoustic-horn-design-the-easy-way-ath4.338806/page-476
Thanks Allen! It is very much work in progress. The last project took over a year!
With the custom active crossover the design goal is to keep as much of the driver sensitivity as possible and use the first few watts of the Neurochrome LM3886 Done Right https://neurochrome.com/products/lm3886-done-right
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I used the Leonard Audio Transmission Line tool to model the 12p80ndv2 box with a large (32cm OD), shallow (3cm total) exponential rear port stuffed with 35kg/m3 material. Effectively aperiodic. I added a rear panel flare to tame resonances, port noise & air speed. Took just a few minutes to home in on good dimensions.
The whole exponential area / dark grey area shown in post 8. My apologies. I made the assumption that readers would recognise screenshots from Leonard Audio.
I wanted a lower f3 than just a sealed box could give (~200). Aperiodic loading could provide a lower f3 point whilst maintaining excellent transient response.
Think of this port as a very short tapered transmission line.
In Leonard try switching between fully sealed, a round reflex port, a short exponential stuffed port and even a aperiodic port like this commercial offering
https://willys-hifi.com/products/scanspeak-aperiodic-variovent-290001
See what happens to resonances and low frequency extension. Tweak dimensions to suit your driver choice, transient and response goals.
I can prepare screens to compare various 12p80nd options if you wish to review?
“The Scanspeak Variovent or 'Flo-Vent' is essentially a resistive reflex port that offers controlled cabinet venting at low frequencies. Installing this vent in a sealed cabinet effectively lowers the woofer Q factor & increases the theoretical cabinet internal volume by a fifth, as seen by the woofer.
The aperiodic vent bridges the gap between infinite baffle & reflex designs, it allows deeper bass from sealed cabinets whilst offering a 3rd order final rolloff, resulting in an improved transient response over the sharp 4th order of traditional bass reflex designs. It is tempting when designing smaller systems with high compliance woofers to use small diameter, longer reflex ports to obtain a low tuned frequency - this can however give rise to chuffing noises from the port - the Variovent does not suffer from this.”
At xmax the 12p80nd would move a lot of air! I didn’t fancy making accommodation for chuffing ports.
I wanted to flatten the response so I would not have to add (too many) additional opamp stages to compensate for a sealed box.
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Do you have a project in mind using the 12p80ndv2?
From the previous design in post 1. You’d need to set your driver, alter to your cab dims and such. Trial and error. Should set you on the right path though.
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I've attached my Leonard Audio file for the 12p80nd. 40L volume with exponential short rear port a la @LineSource posts from many moons ago.
Feedback welcomed.
Feedback welcomed.
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I'm eager to try the next version of ATH4 with box design scripts. I imagine the cabinet shape and location of the wg above will massively increase complexity / CPU calc time as we will no longer be dealing with just quarter symmetry.
In the meantime, please find attached wg at 20/30/45deg. This is just about as clean and linear as I can muster. No doubt it will change once boxed.
What do you think?
In the meantime, please find attached wg at 20/30/45deg. This is just about as clean and linear as I can muster. No doubt it will change once boxed.
What do you think?
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