Hey guys, glad you're enjoying the series 🙂
I've cleared up any scaling questions in the first episode best I can, but a quick tl;dr -
1-dimensional parameters such as frequency, cone diameter, 1/4wave line lengths scale by a factor of 6.
2-dimensional parameters such as cone area, power in watts, port area, scale by a factor of 36.
3-dimensional parameters such as enclosure volume, scale by a factor of 216.
Naturally you cannot divide the VAS or cone area of a 12" woofer by 6 and have the values make sense for a 2" scaled driver since they are not 1 dimensional parameters. Each of the origin parameters that was used to calculate it would need to be divided by 6 first, or you can divide by a multiple of 6 depending on how many parameters were used to calculate it.
There is no real-world use for a driver which nicely mimics a scaled down typical 12" subwoofer. 2" drivers are almost exclusively used for full range application*, so require the ability to play up to 20k. An average subwoofer may have a frequency response of say 20-250hz, meaning a 2" scaled driver would only be usable between 120-1500hz. I dont think anyone has asked for a midbass-only driver in a 2" size so they dont really exist. Luckily, I have had some gents reach out who are able to assemble some one-off drivers to suit this exact application, and I am working with them to dial in the params and characteristics for use in a future season, which is pretty exciting! This would allow for 5mm of xmax instead of 1mm, a 30-50w power handling instead of 15w, and better mechanical cone control as the current driver loses it above 250hz without sufficient load from the enclosure, affecting its performance in lower-tuned ported boxes.
For future seasons I definitely plan on using to 2" drivers to simulate a pair of 12"s, as this will open up the potential for all sorts of crazy hybrid bandpass designs, isobaric, etc. There will also be a season for 2.5" (scaled 15") and maybe 3" (scaled 18") drivers. Who knows maybe even 4 x 1" drivers (6"s) if i can source something suitable.
I have a 6th-order shootout coming soon, there are so many submissions it is hard to know what to pick next! But for those who want to see a 6th it should be a good one.
*I know there is the tang band w2-2040s, but this is trying to play the frequencies of a normal full size subwoofer; its fs of 75hz is far too low (scales to a 12" with an Fs of 12hz) among other parameters, it just wouldn't perform well here.
I've cleared up any scaling questions in the first episode best I can, but a quick tl;dr -
1-dimensional parameters such as frequency, cone diameter, 1/4wave line lengths scale by a factor of 6.
2-dimensional parameters such as cone area, power in watts, port area, scale by a factor of 36.
3-dimensional parameters such as enclosure volume, scale by a factor of 216.
Naturally you cannot divide the VAS or cone area of a 12" woofer by 6 and have the values make sense for a 2" scaled driver since they are not 1 dimensional parameters. Each of the origin parameters that was used to calculate it would need to be divided by 6 first, or you can divide by a multiple of 6 depending on how many parameters were used to calculate it.
There is no real-world use for a driver which nicely mimics a scaled down typical 12" subwoofer. 2" drivers are almost exclusively used for full range application*, so require the ability to play up to 20k. An average subwoofer may have a frequency response of say 20-250hz, meaning a 2" scaled driver would only be usable between 120-1500hz. I dont think anyone has asked for a midbass-only driver in a 2" size so they dont really exist. Luckily, I have had some gents reach out who are able to assemble some one-off drivers to suit this exact application, and I am working with them to dial in the params and characteristics for use in a future season, which is pretty exciting! This would allow for 5mm of xmax instead of 1mm, a 30-50w power handling instead of 15w, and better mechanical cone control as the current driver loses it above 250hz without sufficient load from the enclosure, affecting its performance in lower-tuned ported boxes.
For future seasons I definitely plan on using to 2" drivers to simulate a pair of 12"s, as this will open up the potential for all sorts of crazy hybrid bandpass designs, isobaric, etc. There will also be a season for 2.5" (scaled 15") and maybe 3" (scaled 18") drivers. Who knows maybe even 4 x 1" drivers (6"s) if i can source something suitable.
I have a 6th-order shootout coming soon, there are so many submissions it is hard to know what to pick next! But for those who want to see a 6th it should be a good one.
*I know there is the tang band w2-2040s, but this is trying to play the frequencies of a normal full size subwoofer; its fs of 75hz is far too low (scales to a 12" with an Fs of 12hz) among other parameters, it just wouldn't perform well here.
Hi Sam, thanks for stopping by and answering questions! As you can see by the thread, I'm excited about even the possibility of being part. I think it's an utterly fascinating experiment.
Very exciting! That makes sense; I wondered if you had (many) more submissions than have been shown so far. Are there any tapped horns?
If you'll allow me a tiny nitpick Brian; the measured qts is not quite so bad, at .63
Last edited:
It's lots of fun to make!
Yep the t/s params were a fair bit different to spec when I ran them through the DATs. Annoyingly its a lot softer than I wanted with a much lower Fs, they claim 186hz however my one here is currently sitting at 119hz. I suspect they didnt really run it in much before measuring. Even brand new after just a quick initial free-air run mine was down at 130hz. Thus it came alive in the half-wicked one with the help of the sealed chamber.
Yep the t/s params were a fair bit different to spec when I ran them through the DATs. Annoyingly its a lot softer than I wanted with a much lower Fs, they claim 186hz however my one here is currently sitting at 119hz. I suspect they didnt really run it in much before measuring. Even brand new after just a quick initial free-air run mine was down at 130hz. Thus it came alive in the half-wicked one with the help of the sealed chamber.
That TL was tuned a little too high to take advantage of the cabin resonance with the door open I think. Still, it will be difficult to be the HWO (or the MTHWO, to be precise, LOL).
Practically, putting something the size of a scaled up MTHWO in a car probably won't work for most people.
Practically, putting something the size of a scaled up MTHWO in a car probably won't work for most people.
Lol, I had it powering my 18" bass bin. I use to call it my super bass. I would have it playing with the 2 x 12" BP4 coffee table on the right.
I'm probably just tired from work, but you lost me here. What are you referring to when you say 'that amp'?
Referencing the metal-flamed Audiobahn amp from the late 90s or early 00s. I admit though, I do not see the connection to the thread either, unless the WO image with the AB amp is somehow related.
The enclosure in the trunk with the Audiobahn amp is a Wicked One, which is winning the competition.
Maybe the next session will be :🙏🏻🙏🏻
https://www.parts-express.com/Dayto...-Cone-Midbass-Woofer-8-Ohm-295-416?quantity=1
https://www.parts-express.com/pedocs/specs/295-416--dayton-audio-tcp115-8-specification-sheet.pdf
im sure we could all tear some sh!t up with these 😝 in a variety of ‘sub’ woofer designs in the mid 40s ??
https://www.parts-express.com/Dayto...-Cone-Midbass-Woofer-8-Ohm-295-416?quantity=1
https://www.parts-express.com/pedocs/specs/295-416--dayton-audio-tcp115-8-specification-sheet.pdf
im sure we could all tear some sh!t up with these 😝 in a variety of ‘sub’ woofer designs in the mid 40s ??
It will never be a 4" I'm afraid! That scales to a 24" haha. The biggest I'll probably do is 3" = 18".
episode 8 is out; a Fibonacci spiral shaped front loaded horn / 4th order bandpass ties for first place with the half wicked one (~half a db louder or quieter than the hwo, depending on door open or closed):
10cm2, 10cm2, 20,30,50,80,130,210,340,550,890,1440cm2… 😝. Liberace spiral To 1440 mouth = 37.94 cm x37.94 @ 1/2 wave of ~432 hz (40 cm 🙃
( joking)
( joking)
Last edited:
Hi Dave,
"The Fibonacci spiral: an approximation of the golden spiral created by drawing circular arcs connecting the opposite corners of squares in the Fibonacci tiling"
https://en.wikipedia.org/wiki/Fibonacci_sequence#/media/File:Fibonacci_Spiral.svg
