I recently built an open baffle speaker using a vintage Jensen 15" driver, three Jensen tweeters and a ribbon tweeter.
I'm wanting to build an open back subwoofer using the following wood. I'll cut it in half so that I have two 2' X 2' pieces.
I'll need a 15" 4 ohm driver that has a power handling of at least 25 watts. The crossover will be a passive 12 db/octave around 70Hz so that I can use one amp so the 15" driver needs to be rather efficient.
That said before I go and build a subwoofer I may not need, the main speaker baffle is 2' wide with a 15" Jensen woofer in the center closer to the bottom of the panel. Bass response is decent, but the lower end under maybe 50Hz is somewhat lacking. Would adding wings to the existing baffle make the bass response such that I do not need a sub? If so I've only got room for 1' wings on each side. I can either use a 2' X 2' cut in half or a 4' X 4' cut in half lengthwise whichever will work best.
I'm wanting to build an open back subwoofer using the following wood. I'll cut it in half so that I have two 2' X 2' pieces.
I'll need a 15" 4 ohm driver that has a power handling of at least 25 watts. The crossover will be a passive 12 db/octave around 70Hz so that I can use one amp so the 15" driver needs to be rather efficient.
That said before I go and build a subwoofer I may not need, the main speaker baffle is 2' wide with a 15" Jensen woofer in the center closer to the bottom of the panel. Bass response is decent, but the lower end under maybe 50Hz is somewhat lacking. Would adding wings to the existing baffle make the bass response such that I do not need a sub? If so I've only got room for 1' wings on each side. I can either use a 2' X 2' cut in half or a 4' X 4' cut in half lengthwise whichever will work best.
I suggest to build closed box subwoofer powered by plate amplifier.
Adding wing(s) will not eliminate the need for sub.
Adding wing(s) will not eliminate the need for sub.
I can easily do that, but it defeats the purpose.
I just need bass response down to at least 30Hz, but do not want the typical sound of a closed box subwoofer.
I just need bass response down to at least 30Hz, but do not want the typical sound of a closed box subwoofer.
Here's the speaker location. I have enough room on the left to add a 2' wing to the speaker. What's nice is if I find the wing alone doesn't work it will be wide enough to where I can mount a 15" woofer to it.
Last edited:
Perhaps you can use downfiring woofer like Mr. Nelson used. That way it could fit under your current open baffle.
Otherwise 15" on open baffle U frame (browse old lampizator site for inspiration) would be as big as your current open baffle and probably quite an eyesore.
Besides, you will need lots of inductance to filter out upper frequencies from your open baffle sub, hence i suggested active solution.
Otherwise 15" on open baffle U frame (browse old lampizator site for inspiration) would be as big as your current open baffle and probably quite an eyesore.
Besides, you will need lots of inductance to filter out upper frequencies from your open baffle sub, hence i suggested active solution.
While reading about the open baffle I read where in a smaller room a baffle larger than 35" in width makes the open baffle start to lose its magic and become more like the sound of a speaker in a box.
If I do need a woofer for the bass I'd not mind it sitting next to the existing open baffle. I think it might look quite cool and if I found that I needed two woofers that would look even better to me.
Yes inductance will be a problem, however the inductor will be smaller doing a 12dB/octave crossover.
That said I'm gonna try just the larger baffle and see if that's all I need.
I'm sure the console being right next to the speaker affects the sound some, however when I moved the speaker farther away from the console, the bass didn't sound quite as good.
If I do need a woofer for the bass I'd not mind it sitting next to the existing open baffle. I think it might look quite cool and if I found that I needed two woofers that would look even better to me.
Yes inductance will be a problem, however the inductor will be smaller doing a 12dB/octave crossover.
That said I'm gonna try just the larger baffle and see if that's all I need.
I'm sure the console being right next to the speaker affects the sound some, however when I moved the speaker farther away from the console, the bass didn't sound quite as good.
What is the Fs of this driver? Beyond the normal dipole cancellation issues, below resonance roll-off speeds up even more, so it's harder to get much output below there.
Are you using an equalizer of some kind to deal with dipole cancellation or are you just trying to use the natural response as is?
Here's what it would be for an 8 ohm woofer.
The 4 ohm woofer is this.
The inductors do get expensive that large.
I'd prefer keeping this all tube, however the Magnavox AMP-142 does a good job of heating up the room by itself. Another tube amp would make it even worse. So even though I have a Heathkit A9C amplifier to restore I might not use it, although if I did I'd be able to use a passive RC crossover fed by the preamp I have and have the ability to adjust the level of either the main speaker or woofer to balance them with each other.
That said do I really need to cross the woofer over so low?
If I choose a 150Hz crossover frequency the components are a more reasonable size and cost.
Either way I'm going to try just extending the baffle width first.
The 4 ohm woofer is this.
The inductors do get expensive that large.
I'd prefer keeping this all tube, however the Magnavox AMP-142 does a good job of heating up the room by itself. Another tube amp would make it even worse. So even though I have a Heathkit A9C amplifier to restore I might not use it, although if I did I'd be able to use a passive RC crossover fed by the preamp I have and have the ability to adjust the level of either the main speaker or woofer to balance them with each other.
That said do I really need to cross the woofer over so low?
If I choose a 150Hz crossover frequency the components are a more reasonable size and cost.
Either way I'm going to try just extending the baffle width first.
Last edited:
I forget what the Fs is, but I'm thinking it's around 42Hz. I can measure it when I get home today.
No equalizer used. Gonna try a wing added to the baffle to see if that helps. I do know in certain spots in the room the bass sounds good.
Dipole loss of bass spl makes electric 12dB close to 6dB acoustic, in anechoic environment.
Position of your speaker and new "sub" makes real spl response prediction difficult...
Room modes will make bass sound good in some spot and terrible elsewhere
Position of your speaker and new "sub" makes real spl response prediction difficult...
Room modes will make bass sound good in some spot and terrible elsewhere
I once had that issue with a speaker I had in my room. About the same time I moved the speaker I eliminated all low frequency phase shift from the amp I used to power it and the bass was more even throughout the room.
Another instance I had a bucket sub in one corner and had bass issues and three more placed one in each other corner took care of that.
I'll post photos of the rest of the room when I get home. Perhaps moving the speaker elsewheres in the room and/or moving other stuff around will reduce or eliminate the issue.
Last edited:
Here's photos of the room.
Where the chest of drawers is I cannot put the speaker as a bedroom is on the other side of the wall.
Only place I can think of is to move the console to right at the edge of the door, move the TV down right to the edge of the console and place the speaker in the corner at an angle
Where the chest of drawers is I cannot put the speaker as a bedroom is on the other side of the wall.
Only place I can think of is to move the console to right at the edge of the door, move the TV down right to the edge of the console and place the speaker in the corner at an angle