terryforsythe
Major Contributor
I'm confused. The configuration in your latest drawing is not isobaric.
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- Thread starter BKr0n
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- #122
Ah I see. Ok so the volume of air still needs to be encapsulated. I thought it was just merely making it push-pull. My bad...
terryforsythe
Major Contributor
Where is the acoustic output coming from?
In an isobaric design a first woofer has one side exposed to the inside of the cabinet, and the other side pushing a second woofer. The opposite side of the second woofer provides the acoustic output. I.e.:
The top picture is with the woofers wired in phase. In the bottom picture they are wired out of phase. That way, both cones are always moving in the same direction.
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- #125
Where is the acoustic output coming from?
In an isobaric design a first woofer has one side exposed to the inside of the cabinet, and the other side pushing a second woofer. The opposite side of the second woofer provides the acoustic output. I.e.:
The top picture is with the woofers wired in phase. In the bottom picture they are wired out of phase. That way, both cones are always moving in the same direction.
I'll be using both sides. As one driver pushes, the other becomes the acoustically driven pull and outputs the signal through the ports. In essence I'm using both sides of the enclosure as one large port.
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- #126
@voodooless you were right! WinISD is SUUUUUUUUUUUPER simple lol
If the port openings are just at the top OR just at the bottom (behind only ONE of the woofers), I think that configuration would be a "4th order isobaric bandpass" enclosure. If there are port openings at both the top AND bottom (behind BOTH woofers), I don't know what it is, but at at glance it looks like the output from the top ports would be out-of-phase with the output from the bottom port and you'd get a lot of cancellation.
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- Thread Starter
- #128
Wouldn't that make it an 8th order then?
a4eaudio
Senior Member
I've used the RS225 in an isobaric two-way. Isobaric is quite inefficient but can work well in certain situations. Be warned that there is something WinISD calculates wrong for isobaric - I don't remember what it is but maybe impedance or total SPL.
a4eAudio.com - Bosi 225
My Bosi 225 design was created as an entry to the 2023 InDIYana theme competition. Surprisingly it won 1st place. Below is a write-up of how the speaker came about and some of the decisions that I made in building and designing it. Tweeter: Satori TW29RN-B-8 Woofer: Dayton Audio RS225-8 (x2
www.a4eaudio.com
I've also used the 4 inch RS100 and 10 inch paper cone RS270P-4 but it looks like they discontinued the 10-inch versions in the last month or two. In general the Reference Series (aluminum and paper) are great for the money.
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- #130
Works for me! Although, funny enough, isobaric actually gives me a bit of wiggle room. Got about 32 liters of play, but that's also without me lining and dampening the enclosure.I've used the RS225 in an isobaric two-way. Isobaric is quite inefficient but can work well in certain situations. Be warned that there is something WinISD calculates wrong for isobaric - I don't remember what it is but maybe impedance or total SPL.
a4eAudio.com - Bosi 225
My Bosi 225 design was created as an entry to the 2023 InDIYana theme competition. Surprisingly it won 1st place. Below is a write-up of how the speaker came about and some of the decisions that I made in building and designing it. Tweeter: Satori TW29RN-B-8 Woofer: Dayton Audio RS225-8 (x2
I've also used the 4 inch RS100 and 10 inch paper cone RS270P-4 but it looks like they discontinued the 10-inch versions in the last month or two. In general the Reference Series (aluminum and paper) are great for the money.
Also wow this thing is way bigger than I thought it would be (phrasing boom). 10"W 19.5"L 27"H
kemmler3D
Master Contributor
That's verging on floorstander territory already... Maybe you could make things easier on yourself and do "bass modules" / subwoofers with the SEAS drivers and stick the MTMs on top? Still somewhat portable but you won't have to go through all these tricky designs getting them all in one cabinet.
Sorry that I am always trying to talk you out of stuff.
- Thread Starter
- #132
Nah no worries budThat's verging on floorstander territory already... Maybe you could make things easier on yourself and do "bass modules" / subwoofers with the SEAS drivers and stick the MTMs on top? Still somewhat portable but you won't have to go through all these tricky designs getting them all in one cabinet.
Sorry that I am always trying to talk you out of stuff.
Like I was saying before, the daytons in iso only need a little over 9 liters, which is more than doable. Can probably do it sealed as well. Just may need to try another orientation for the subs and move some stuff around. The way I look at it, I'm more hopeful than before because thanks to @voodooless another solution presented itself. As long as I have a path forward I'm good lol
Edit: btw ONE purifi woofer has about 5.5 liters as it's Vas. 9 is definitely doable lol
It looks like I was editing my post while you were posting.
I think the term "8th order" implies that the rolloff rate below the tuning frequency would be 8 x 6 = 48 dB per octave, and it is not obvious to me that such would be the case.
a4eaudio
Senior Member
Which specific Dayton driver are you considering? The only specific one I saw mentioned was the Ultimax.
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- #135
Dayton Audio - RSS210HO-4 8" Reference HO Subwoofer 4 Ohm
RSS210HO-4 8" Reference HO Subwoofer 4 Ohm
www.daytonaudio.com
Nice flat response and low Vas
a4eaudio
Senior Member
Yes those are good. Note, for isobaric you will wire two in parallel so would need to get the 8 ohm version, when wired in parallel will give you 4 ohms.
Here is a design with the RSS210 by Dan Poinsett, one of the current owners of CSS.
projectgallery.parts-express.com
Here is a design with the RSS210 by Dan Poinsett, one of the current owners of CSS.
The Boxers | Parts Express Project Gallery
projectgallery.parts-express.com
- Thread Starter
- #137
Using a Hypex 253 so 2 ohms for me bby
Great detective work! I hope it meets your design targets.
a4eaudio
Senior Member
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