Recess wall is out 1-1/2” from the cone all around and rounded with a generous 1/2 round radius. Should be visible in the pictures, I think.
I suppose if that sounds bad, I can go even bigger.
Hardly any minor alteration of a speaker is worth pursuing in advance of testing in the room. Might prove an advantage.
Question to all: when you have a second driver in an OB, is that any kind of sound "leak" like when the rear wave sneaks around to meet the front wave?
B.
Question to all: when you have a second driver in an OB, is that any kind of sound "leak" like when the rear wave sneaks around to meet the front wave?
B.
looking good!
GREAT DEAL -Free
Cerwin Vega WOFH12209 - 12" Replacement Woofer - RiotSound
here's some more -
Dayton PS220-8 with Eminence Alpha 15A H-Frame Open Back -
Techtalk Speaker Building, Audio, Video Discussion Forum
AudioRoundTable.com: Speaker >> Dayton Audio/Eminence Full Range Single Driver
Another option you could try is find a Cerwin Vega speaker that uses the 12" woofer, build a box with the dimensions ( sealed? ported?) And have a baffle board extended up to hold the Dayton PS driver.
Cerwin Vega 26 Speakers 12 inch woofer- two way Photo #154867 - Canuck Audio Mart
http://www.humblehomemadehifi.com/download/Humble Homemade Hifi_Modulus.pdf
https://techtalk.parts-express.com/forum/tech-talk-forum/25144-introducing-the-basslines-long/page10
GREAT DEAL -Free
Cerwin Vega WOFH12209 - 12" Replacement Woofer - RiotSound
here's some more -
Dayton PS220-8 with Eminence Alpha 15A H-Frame Open Back -
Techtalk Speaker Building, Audio, Video Discussion Forum
AudioRoundTable.com: Speaker >> Dayton Audio/Eminence Full Range Single Driver
Another option you could try is find a Cerwin Vega speaker that uses the 12" woofer, build a box with the dimensions ( sealed? ported?) And have a baffle board extended up to hold the Dayton PS driver.
Cerwin Vega 26 Speakers 12 inch woofer- two way Photo #154867 - Canuck Audio Mart
http://www.humblehomemadehifi.com/download/Humble Homemade Hifi_Modulus.pdf
https://techtalk.parts-express.com/forum/tech-talk-forum/25144-introducing-the-basslines-long/page10
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Crossover attempt with no measurements, THIS IS A GUESS:
- looks like Fred smoothed the Dayton and low passed to his woofer around 150 hz
(we don't know what the slopes are for your drivers)
Dayton PS220-8 with Eminence Alpha 15A H-Frame Open Back -
Techtalk Speaker Building, Audio, Video Discussion Forum
AudioRoundTable.com: Speaker >> Dayton Audio/Eminence Full Range Single Driver
--
from
http://www.quarter-wave.com/OBs/OB_Design_Part_1.pdf
Martin King used a 9.1 mH and 68 ufd low pass for Eminence Alpha 15A, 8 OHM driver about 200 hz crossover
Interesting check this table
2nd Order / 12 db Butterworth Crossover Table
Looks close to what Martin King has for a low pass. (9.1mH and 75 ufd)
--
Your Cerwin Vega says 6 ohm, for 130 hz 6 ohm @ 11 mH and 150 ufd low pass
(or whatever point you want to try)
--
(disregard that the following is a 4 ohm crossover, this has a 11mh coil and 350 ufd cap)
you could hook this up and listen. Good? Bad?- Change the cap 150, 100, 200, etc-electrolytic cap-watch how you hook it up.
Parts Express 80 Hz Low Pass 4 Ohm Crossover
- looks like Fred smoothed the Dayton and low passed to his woofer around 150 hz
(we don't know what the slopes are for your drivers)
Dayton PS220-8 with Eminence Alpha 15A H-Frame Open Back -
Techtalk Speaker Building, Audio, Video Discussion Forum
AudioRoundTable.com: Speaker >> Dayton Audio/Eminence Full Range Single Driver
--
from
http://www.quarter-wave.com/OBs/OB_Design_Part_1.pdf
Martin King used a 9.1 mH and 68 ufd low pass for Eminence Alpha 15A, 8 OHM driver about 200 hz crossover
Interesting check this table
2nd Order / 12 db Butterworth Crossover Table
Looks close to what Martin King has for a low pass. (9.1mH and 75 ufd)
--
Your Cerwin Vega says 6 ohm, for 130 hz 6 ohm @ 11 mH and 150 ufd low pass
(or whatever point you want to try)
--
(disregard that the following is a 4 ohm crossover, this has a 11mh coil and 350 ufd cap)
you could hook this up and listen. Good? Bad?- Change the cap 150, 100, 200, etc-electrolytic cap-watch how you hook it up.
Parts Express 80 Hz Low Pass 4 Ohm Crossover
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If you want to do OB, especially with 12" woofers, I suggest you browse this thread:
Fast, fun, Inexpensive OB project
This will give you the basics you need to start an OB project like yours.
Fast, fun, Inexpensive OB project
This will give you the basics you need to start an OB project like yours.
Thanks for your comments and links, guys!
I put these together as I originally intended, just to test ‘em. I’m using the Cerwin-Vega crossover on the woofers only as my low-pass filter. The full-range drivers are unfiltered. I’m running these in parallel and my big ol’ Krell is having no trouble at all. These really sound quite good and bass isn’t bad at all. They don’t have big subwoofer bass, but it’s certainly there!
In a few days I’ll pull the drivers back out and sand, stain and finish these. I’ll fiddle with low-pass more, later on.
Not sure why but my attachments are displayed sideways here..
I put these together as I originally intended, just to test ‘em. I’m using the Cerwin-Vega crossover on the woofers only as my low-pass filter. The full-range drivers are unfiltered. I’m running these in parallel and my big ol’ Krell is having no trouble at all. These really sound quite good and bass isn’t bad at all. They don’t have big subwoofer bass, but it’s certainly there!
In a few days I’ll pull the drivers back out and sand, stain and finish these. I’ll fiddle with low-pass more, later on.
Not sure why but my attachments are displayed sideways here..
Attachments
Thanks. They’d look better with a less gaudy woofer but it’s what I had to work with. Once the baffles are properly sanded, stained and finished, I think they won’t look too bad at all. 🙂
you could add these
https://www.ebay.ca/sch/i.html?_from=R40&_nkw=cerwin+vega+badge&_sacat=0&_sop=15
https://www.ebay.ca/sch/i.html?_from=R40&_nkw=cerwin+vega+badge&_sacat=0&_sop=15
To start, just run REW with no filter, EQ, or XO, just to see what you've got to start with.
Misleading to do the usual one-meter on-axis. You want readings at your chair or perhaps in a few locations you can precisely re-locate for interactive testing.
B.
Misleading to do the usual one-meter on-axis. You want readings at your chair or perhaps in a few locations you can precisely re-locate for interactive testing.
B.
Taming the open baffle woofer.
What's different about implementing a low pass filter on OB as opposed to a typical box speaker. I'll over-explain this a little, so bear with me if you know a lot of this.
When you choose a woofer and put it in a box, you get a fairly flat response within the woofer's bandwidth, if you've done a decent job of picking a box and woofer. The right woofer in the right box can be reasonably flat from 40 to 2500 Hz. Great. Now you want a midrange or fullrange driver to take over from the woofer. You choose a crossover point that will work for both drivers, maybe 300 Hz or 750 Hz. Once that point is chosen, you connect your crossover of 1st, 2nd, 3rd, 4th, etc order you think will work for your design. Adjust the level of the mid and add a high pass, voila! You're done. Your woofer plays flat(ish) from F3 to the point where the low pass filter rolls it off.
Open Baffle is different. Unless you have a giant baffle, your woofer is going to suffer bass loss. Why? Because the pressure coming off the back of the woofer is 180 degrees out of phase with the pressure at the front of the woofer. So the opposite pressures cancel out each other. You can easily hear that by pulling a woofer out of its box and playing it "nude." No bass. That's why we put them in a box, to keep the front and back pressures from cancelling each other. The frequencies at which they begin to cancel depend on the size of the baffle.
What does that cancellation look like? It looks like a rising response. In other words; the woofer response is no longer flat, but increasing in loudness as the frequency goes up. Or looked at the other way, decreasing in loudness as the frequencies descend. We no longer have a flat response from the woofer, so now if we put a low pass filter on the woofer, the low pass will still work, but you won't have a flat woofer response that drops off at 12-24 dB/octave where you want it. Instead you'll have a response that gets much louder as the frequencies go up, with some shallow roll off at the top.
I'll make some illustration graphs and post them here as a picture is with 1000 words. Then we can talk about how to deal with the very "unflat" Open Baffle woofer.
What's different about implementing a low pass filter on OB as opposed to a typical box speaker. I'll over-explain this a little, so bear with me if you know a lot of this.
When you choose a woofer and put it in a box, you get a fairly flat response within the woofer's bandwidth, if you've done a decent job of picking a box and woofer. The right woofer in the right box can be reasonably flat from 40 to 2500 Hz. Great. Now you want a midrange or fullrange driver to take over from the woofer. You choose a crossover point that will work for both drivers, maybe 300 Hz or 750 Hz. Once that point is chosen, you connect your crossover of 1st, 2nd, 3rd, 4th, etc order you think will work for your design. Adjust the level of the mid and add a high pass, voila! You're done. Your woofer plays flat(ish) from F3 to the point where the low pass filter rolls it off.
Open Baffle is different. Unless you have a giant baffle, your woofer is going to suffer bass loss. Why? Because the pressure coming off the back of the woofer is 180 degrees out of phase with the pressure at the front of the woofer. So the opposite pressures cancel out each other. You can easily hear that by pulling a woofer out of its box and playing it "nude." No bass. That's why we put them in a box, to keep the front and back pressures from cancelling each other. The frequencies at which they begin to cancel depend on the size of the baffle.
What does that cancellation look like? It looks like a rising response. In other words; the woofer response is no longer flat, but increasing in loudness as the frequency goes up. Or looked at the other way, decreasing in loudness as the frequencies descend. We no longer have a flat response from the woofer, so now if we put a low pass filter on the woofer, the low pass will still work, but you won't have a flat woofer response that drops off at 12-24 dB/octave where you want it. Instead you'll have a response that gets much louder as the frequencies go up, with some shallow roll off at the top.
I'll make some illustration graphs and post them here as a picture is with 1000 words. Then we can talk about how to deal with the very "unflat" Open Baffle woofer.
In practice, the back waves have all kinds of paths and purposes of which annihilation takes place only when the phases are bad at specific frequencies. And the room acoustics will have substantial impact. And nobody has mentioned the enormous bump provided by the driver's free-air resonance which may be in a very welcome band.
Aside from the physics of baffles with real simple shapes, wait to test before committing to anybody's theory and that includes high respected Linkwitz.
B.
Aside from the physics of baffles with real simple shapes, wait to test before committing to anybody's theory and that includes high respected Linkwitz.
B.
Yes, things get complicated with with baffle sizes and shapes, room reflection, room gain, driver Qts and so on. But most mid Q woofers on practical size baffles in a normal room will rise (or fall off) about 9dB/octave. Bass losses can be 10dB or more compared to a box speaker, you have to take that into account.
This is the starting point and very important to understand for proper tonal balance on O.B.
This is the starting point and very important to understand for proper tonal balance on O.B.
+1
I've been on my "soap box" about OB annihilation anxiety for a long time. Without a quibble, Pano's "executive summary" version surely put you in the ballpark. But is that good enough to start wiring an LT circuit? Betcha not.
I can't recall seeing measurements in a typical room compared to acoustics model. Did Linkwitz post some, even incidentally?
I have a feeling that many folks on this forum share a liking for unboxed sound. I certainly do.*
B.
* big DIY ESLs
I've been on my "soap box" about OB annihilation anxiety for a long time. Without a quibble, Pano's "executive summary" version surely put you in the ballpark. But is that good enough to start wiring an LT circuit? Betcha not.
I can't recall seeing measurements in a typical room compared to acoustics model. Did Linkwitz post some, even incidentally?
I have a feeling that many folks on this forum share a liking for unboxed sound. I certainly do.*
B.
* big DIY ESLs