Hi all,
I completed a fun project using some concepts I've been learning and throwing around ideas with and wanted to test some things and try a few new things and it gave me something to work on through the hurricanes instead of wondering what it would be like to use my subs as canoes after being washed away in hurricanes (I'm in Florida). Finished this one up and just wanted to share the results because its different and probably about as DIY as it gets in many ways. So I hope you can come by an take a laugh at it or maybe some interest in it, either way, as I went to clown town on this build and tried a little wacky finish as practice using some materials new to me, etc.
GRS12SW-4 x 8 Drivers, These are cheap, was $25 a pop. High Qts, Fs in around 30hz in series. 8.5mm excursion but its good beyond that until it hits xmech limit. I have used these in the past in open baffle platforms to punish out 10hz and up for tactile response and despite being cheap and lower xmax, they do it quite well. So I figured, let's put them in a bigger open baffle and stand it up as a tower.
I recently made some threads to ask questions, figure out how to do the right baffle design, ended up with a W-frame, which lead me down the rabbit hole of cavities and slots and slot loading, mass loading, etc. Really fun stuff. I put all that into practice and made something that works (I think?).
I wanted to keep opposing pairs for vibration suppression in the structure as I've done this in the past and I really like the effect. My trinkets and drinks don't walk off the tops of the cabinets anymore which is fabulous to not have invisible cats in the rooms.
My old threads:
Here's the results, for the TL;DR people. The build log and image dump will be in the following posts.
Thanks all for any help who contributed to my threads and questions... it was very helpful to at least exchange ideas and learn about anything offered.
GRS 12SW-4 x 8 Drivers
W-Frame Open Baffle (51" x 21" x 13.25")
Slot loaded cavities (11" x 11" x 3")
Handles 960w total, but only needs less than 200w to hit excursion limits below 28hz
Response with no filters, no EQ, no low pass filter, etc, Cavity resonance peak frequency range kept (in that 200hz range). Roll off starts around 28hz or so. Needs a low pass filter for practical use, but this is the raw response to single digits and I took it as high as it would go until I saw compression starting in infrasonic values which was just under 20hz here. If I high pass this so its only 30hz and up, I can take this output much higher. So its capable of doing two different things based on the bandwidth I want to keep. Either way, its enough output for me in a room on its own for virtually anything just from cone area.
Very best,
I completed a fun project using some concepts I've been learning and throwing around ideas with and wanted to test some things and try a few new things and it gave me something to work on through the hurricanes instead of wondering what it would be like to use my subs as canoes after being washed away in hurricanes (I'm in Florida). Finished this one up and just wanted to share the results because its different and probably about as DIY as it gets in many ways. So I hope you can come by an take a laugh at it or maybe some interest in it, either way, as I went to clown town on this build and tried a little wacky finish as practice using some materials new to me, etc.
GRS12SW-4 x 8 Drivers, These are cheap, was $25 a pop. High Qts, Fs in around 30hz in series. 8.5mm excursion but its good beyond that until it hits xmech limit. I have used these in the past in open baffle platforms to punish out 10hz and up for tactile response and despite being cheap and lower xmax, they do it quite well. So I figured, let's put them in a bigger open baffle and stand it up as a tower.
I recently made some threads to ask questions, figure out how to do the right baffle design, ended up with a W-frame, which lead me down the rabbit hole of cavities and slots and slot loading, mass loading, etc. Really fun stuff. I put all that into practice and made something that works (I think?).
I wanted to keep opposing pairs for vibration suppression in the structure as I've done this in the past and I really like the effect. My trinkets and drinks don't walk off the tops of the cabinets anymore which is fabulous to not have invisible cats in the rooms.
My old threads:
Here's the results, for the TL;DR people. The build log and image dump will be in the following posts.
Thanks all for any help who contributed to my threads and questions... it was very helpful to at least exchange ideas and learn about anything offered.
GRS 12SW-4 x 8 Drivers
W-Frame Open Baffle (51" x 21" x 13.25")
Slot loaded cavities (11" x 11" x 3")
Handles 960w total, but only needs less than 200w to hit excursion limits below 28hz
Response with no filters, no EQ, no low pass filter, etc, Cavity resonance peak frequency range kept (in that 200hz range). Roll off starts around 28hz or so. Needs a low pass filter for practical use, but this is the raw response to single digits and I took it as high as it would go until I saw compression starting in infrasonic values which was just under 20hz here. If I high pass this so its only 30hz and up, I can take this output much higher. So its capable of doing two different things based on the bandwidth I want to keep. Either way, its enough output for me in a room on its own for virtually anything just from cone area.
Very best,
The above shows the panel movement without bracing and without both bank active. With bracing and bot banks active, there is no movement on the floating panel wings anymore.
Very best,
It sounds great, lots of attack and slam, digs deeper than I can hear. I currently have been listening to it in a room near a wall but not stuffed in a corner. I'll measure in room soon. Great for music. Works well even for theater (against all advice using open baffle subs for that). The stacks of drivers forming a short array seems to have a benefit in room, so I'll measure that soon to see if it does help or if it's just current position, etc.
Very best,
It's pretty heavy. But not crazy. I could easily move it with a hand truck (dolly).
Each driver is about 8lbs each
So 8 x 8 = 64lbs
The manifold and everything, I didn't weigh, but its easily 50~60lbs. I could life it without drivers easily.
So maybe 120lbs?
Very best,
That’s interesting what happens with the 80hz low pass to the content above 200hz compared to 100 and 120…..it’s lower in amplitude but all broken up…..as if the fundamental energy is reduced but the reflected, phase reversed energy remains. Hmmmm.
Hi,
I didn't measure above 400hz since its a subwoofer and has no business above 100~120hz in the first place. I just measured that high to see what happens above the slot cavities but didn't go beyond that since it won't be used there at all (as it would include the slot cavity resonance in the output and that's not good).
Damping material in this open baffle build won't do anything for resonance on a long panel--bracing solves that.
Very best,
Its not exactly bad either, just is, EQ tames it for the most part.
Yeah thats not true lol. You can prove that to your self by removing the damping material and taking a measurement. In a slot loaded driver, damping material lessens the flaws of the slot. I am not talking about resonances of a panel, I am talking about the resonance of the air column in the slot. I have measurements of my ppsl and they are different depending on the damping situation.
I wasn't talking specifically about only the slot. That's different, its a small cavity. I was saying in general such as the back chamber, it is much larger. I did measure something similar to what you're asking. I did several different kinds of stuffing in the slots to see the effect on air velocity and the response change.
Here's the front slots unstuffed, partially stuffed and nearly fully stuffed.
I also did some stuffing in the rear chamber to see the effect.
It didn't solve resonance issues that were structural. It just changes things that stem from air velocity, at least, I think.
Very best,
The slot cancellations/resonances are due to harmonic destruction/summation via reflections.
Ty for taking the time to share.
Your measurements are a real eye opener on the variations of results that play out in real life. Strange how the sensitivity increased with partial damping materials. One would have to question the efficacy your damping material. There's like three good choices and it looks like you are potentially using open cell foam? Open cell foam, according to my studies, isn't the most potent form of damping but it all depends on desired effect. The biggest tell is the amount of change from fully no damping to "fully" damped. Not a lot going on. To your benefit, the problem areas are outside of your desired pass band. I can only speak to my simulations but from my research you need fiberglass/rockwool, and to fill the rear 50% of the cavity. Execute that properly and you will have a FR similar to a regular forward facing woofer.
Ty for taking the time to share.
Your measurements are a real eye opener on the variations of results that play out in real life. Strange how the sensitivity increased with partial damping materials. One would have to question the efficacy your damping material. There's like three good choices and it looks like you are potentially using open cell foam? Open cell foam, according to my studies, isn't the most potent form of damping but it all depends on desired effect. The biggest tell is the amount of change from fully no damping to "fully" damped. Not a lot going on. To your benefit, the problem areas are outside of your desired pass band. I can only speak to my simulations but from my research you need fiberglass/rockwool, and to fill the rear 50% of the cavity. Execute that properly and you will have a FR similar to a regular forward facing woofer.