Hi all,
Recently picked up a cheap driver that I wanted to play with and figured I could use a new sub in my office. The GRS 12SW-4HE is $60 shipped with a little tax from P.E. It's sensitivity is ok, around 84db, supposedly is capable of 20hz and has decent xmax of 12.5mm so figured it could be a fun little driver to tinker with. I modeled it a few times in WinISD and played around with bass reflex enclosure designs, simple ones, with a slot port folded inside and used Subbox.pro to do simple models to look at for size and measurements while keeping consistent net internal volume. I'm powering this with a 50 watt amp that I have laying around (an AudioSource AMP100) since its near field it doesn't need hardly any power to do its job (less than a meter from my skull). I'm using a Dayton DSP-LF as my DSP to handle crossover and PEQ. Once I learned iWoofer app, it was much easier to handle this.
Note, I'm not a woodworker or carpenter, I have a few tools from over the years. I made plenty of mistakes. Still learning!
WinISD Modeling
Here's my WinISD modeling. I only enabled a lowpass filter to keep it from attempting full range.
3 Cubic Foot Bass Reflex Enclosure with a 21hz Tuning Slot Port
Modeling at 3 feet and 100 watts (more than I will actually use, I will actually use 50 watts approximately)
Kept the port big enough to keep air velocity well below 18 m/s
At this close range and low power it never approaches its xmax limit, so it's good all the way to its 250 watt power handling in this regard
Modeling the Enclosure
I used Subbox.pro website to do a basic model. Since it's a bass reflex enclosure, I wanted to do a simple slot port folded inside which this modeling software does an ok job of as I don't like the look of big round ports and wanted to build a folded slot port anyways for fun and to get some more experience with that.
The net internal volume is being kept at 3 cubic feet
The slot port is tuned to 21hz and is 1.36" x 14.74" x 35.23" as modeled (in reality I rounded this a little for simplicity)
External cabinet dimensions are 22" x 16" x 22.63"
I allowed for up to 0.65~0.85 Ft^3 displacement for the driver and bracing components
Building It!
I needed more clamps, so used this as an opportunity to pick up more 36" and 24" clamps. I picked them up from Harbor Freight for $8~6 respectively and they work like champs.
I picked up 1.25" wood screws (100x) & some larger black screws for mounting the driver
I picked up some Titebond Original Wood Glue (16oz)
I picked up some Wood Filler paste to fill in holes and gaps
I picked up a single sheet of Birch plywood from Lowes (lighter weight was my primary reason), it was kind of pricey at $80
I picked up some Minwax Dark Walnut stain ($7) & some Matte Clear Coat ($6)
I picked up some heavy binding posts that just get mounted via drilling a hole and pushing them in ($10)
Tools I already had: Jigsaw, Orbital Sander, Drills & bits (including a counter sink bit), some clamps, hot glue gun & glue sticks, caulk
I had some spade terminals and speaker wire already
Phew, ok, here's some photos of the building process as I photo documented most of the big steps along the way. I'm in Florida and this got interrupted with Hurricane Ian so I was outside, inside, and then got called into the hospital for disaster potential, and then got back to it to finish up. So it's messy. Sorry. But hey, it shows that you can do it without a garage and without a shop, etc.
Cutting the birch ply with a jigsaw
I marked my driver circle cutout with a jig I had for my dremel, could have just used a screw and string and did the same thing though. It doesn't have to be a perfect circle.
Cut my janky circle, just enough to drop in the driver. Test fitted and left it at that. I drilled into the inside circle to make a hole and then the jigsaw went in and I just slow cut around the edge. Pretty simple, but not super precise or pretty.
For joining pieces, I opted to use a counter-sink bit and drop in wood machine screws in addition to the wood glue. I wanted to do this because a lot of my jigsaw cuts were not perfect. I wish I had a table saw or track saw, but I didn't for this project, so messy edges were a reality. I just sanded things and made them fit with the screws and glue. I knew I could fill in holes and gaps with wood filler paste later and sand it away.
Joining sides, clamping, and putting this huge mess on my office floor due to rain and storms here in Florida.
Ruined a blanket we were throwing away anyways...
Big helper came into the cluttered nasty office. How cluttered? Microscope, junk, drills, 3 year old, big sub box, you know how it goes...
Passing inspections...
Clamping the inner port below the driver
Dry fitting some pieces and cut a "window brace." It's not pretty. I just drilled holes and used the jigsaw to cut windows.
Dry fitting the bottom of the enclosure with the port. Preparing to put bracing in the port itself. I cut small pieces and glued them along the middle of the port on both tracks.
You can see some bracing in the port here (lower left) and just have the window brace sitting in there crooked just to see how it will sit and fit and all that...
More storms, back into the house to clamp some more with some help...
Drilled 1/4th inch holes into the back of the box and then inserted the heavy binding posts and pounded them in with a weight...
On the inside, I attached spades and wire to the inner binding post terminals and then hot glued all of it so that it wouldn't rattle or more at all. It looks like a hot mess and is. But it stays in place. I hot glued the wire along the edges and through the window brace to the driver location and left only some of it free hanging to attach to avoid any rattling wire dangling.
Here you can see the wire snaking through and glued to it, that's the top of the enclosure and above the port. Also a look at the slot port itself before I close up the box.
A final peak inside before the top goes on to seal the entire box other than the port and the driver location.
Continued....
Very best,
Recently picked up a cheap driver that I wanted to play with and figured I could use a new sub in my office. The GRS 12SW-4HE is $60 shipped with a little tax from P.E. It's sensitivity is ok, around 84db, supposedly is capable of 20hz and has decent xmax of 12.5mm so figured it could be a fun little driver to tinker with. I modeled it a few times in WinISD and played around with bass reflex enclosure designs, simple ones, with a slot port folded inside and used Subbox.pro to do simple models to look at for size and measurements while keeping consistent net internal volume. I'm powering this with a 50 watt amp that I have laying around (an AudioSource AMP100) since its near field it doesn't need hardly any power to do its job (less than a meter from my skull). I'm using a Dayton DSP-LF as my DSP to handle crossover and PEQ. Once I learned iWoofer app, it was much easier to handle this.
Note, I'm not a woodworker or carpenter, I have a few tools from over the years. I made plenty of mistakes. Still learning!
WinISD Modeling
Here's my WinISD modeling. I only enabled a lowpass filter to keep it from attempting full range.
3 Cubic Foot Bass Reflex Enclosure with a 21hz Tuning Slot Port
Modeling at 3 feet and 100 watts (more than I will actually use, I will actually use 50 watts approximately)
Kept the port big enough to keep air velocity well below 18 m/s
At this close range and low power it never approaches its xmax limit, so it's good all the way to its 250 watt power handling in this regard
Modeling the Enclosure
I used Subbox.pro website to do a basic model. Since it's a bass reflex enclosure, I wanted to do a simple slot port folded inside which this modeling software does an ok job of as I don't like the look of big round ports and wanted to build a folded slot port anyways for fun and to get some more experience with that.
The net internal volume is being kept at 3 cubic feet
The slot port is tuned to 21hz and is 1.36" x 14.74" x 35.23" as modeled (in reality I rounded this a little for simplicity)
External cabinet dimensions are 22" x 16" x 22.63"
I allowed for up to 0.65~0.85 Ft^3 displacement for the driver and bracing components
Building It!
I needed more clamps, so used this as an opportunity to pick up more 36" and 24" clamps. I picked them up from Harbor Freight for $8~6 respectively and they work like champs.
I picked up 1.25" wood screws (100x) & some larger black screws for mounting the driver
I picked up some Titebond Original Wood Glue (16oz)
I picked up some Wood Filler paste to fill in holes and gaps
I picked up a single sheet of Birch plywood from Lowes (lighter weight was my primary reason), it was kind of pricey at $80
I picked up some Minwax Dark Walnut stain ($7) & some Matte Clear Coat ($6)
I picked up some heavy binding posts that just get mounted via drilling a hole and pushing them in ($10)
Tools I already had: Jigsaw, Orbital Sander, Drills & bits (including a counter sink bit), some clamps, hot glue gun & glue sticks, caulk
I had some spade terminals and speaker wire already
Phew, ok, here's some photos of the building process as I photo documented most of the big steps along the way. I'm in Florida and this got interrupted with Hurricane Ian so I was outside, inside, and then got called into the hospital for disaster potential, and then got back to it to finish up. So it's messy. Sorry. But hey, it shows that you can do it without a garage and without a shop, etc.
Cutting the birch ply with a jigsaw
I marked my driver circle cutout with a jig I had for my dremel, could have just used a screw and string and did the same thing though. It doesn't have to be a perfect circle.
Cut my janky circle, just enough to drop in the driver. Test fitted and left it at that. I drilled into the inside circle to make a hole and then the jigsaw went in and I just slow cut around the edge. Pretty simple, but not super precise or pretty.
For joining pieces, I opted to use a counter-sink bit and drop in wood machine screws in addition to the wood glue. I wanted to do this because a lot of my jigsaw cuts were not perfect. I wish I had a table saw or track saw, but I didn't for this project, so messy edges were a reality. I just sanded things and made them fit with the screws and glue. I knew I could fill in holes and gaps with wood filler paste later and sand it away.
Joining sides, clamping, and putting this huge mess on my office floor due to rain and storms here in Florida.
Ruined a blanket we were throwing away anyways...
Big helper came into the cluttered nasty office. How cluttered? Microscope, junk, drills, 3 year old, big sub box, you know how it goes...
Passing inspections...
Clamping the inner port below the driver
Dry fitting some pieces and cut a "window brace." It's not pretty. I just drilled holes and used the jigsaw to cut windows.
Dry fitting the bottom of the enclosure with the port. Preparing to put bracing in the port itself. I cut small pieces and glued them along the middle of the port on both tracks.
You can see some bracing in the port here (lower left) and just have the window brace sitting in there crooked just to see how it will sit and fit and all that...
More storms, back into the house to clamp some more with some help...
Drilled 1/4th inch holes into the back of the box and then inserted the heavy binding posts and pounded them in with a weight...
On the inside, I attached spades and wire to the inner binding post terminals and then hot glued all of it so that it wouldn't rattle or more at all. It looks like a hot mess and is. But it stays in place. I hot glued the wire along the edges and through the window brace to the driver location and left only some of it free hanging to attach to avoid any rattling wire dangling.
Here you can see the wire snaking through and glued to it, that's the top of the enclosure and above the port. Also a look at the slot port itself before I close up the box.
A final peak inside before the top goes on to seal the entire box other than the port and the driver location.
Continued....
Very best,
Top clamped on and glued for the night.
The final clamping from the front. After this it's finishing and testing.
Here's some messy examples of the wood filler paste. I just slapped it into place over all the counter sunk screw heads and filled in any major gaps or imperfections where I joined the boards together after I sanded things a little to fit best.
Sanding the enclosure. On the left I have no sanded yet so you can see the messy wood filler paste. On the right you can see where I sanded just so you can see what it looks like after filling in screw holes. You can see them of course, but they're smooth and no metal showing.
This part wasn't needed, but I have an old router and a 3/8th inch round over bit I already had. I just did the edges to get a rounded edge and corners. Not hard to do. Wish I had a hand trimmer instead for this kind of work. Might pick one up. This thing is overkill for this. I like this natural look. I almost left it like this and was just going to seal it. But it would look too bright in my shabby dark old office area and rarely be seen anyways.
Testing some dark walnut stain on the bottom of the box. You can see where I didn't clean up some glue. It's the bottom, so that's fine.
Stained the whole cabinet. Darker than I wanted in reality. I tested another piece and sanded it and didn't like how that worked, so I left it alone. Next time I'll go a little lighter on the stain. I think I would have liked half this darkness maybe. Still, not a problem, originally was going to just make it duratex black or something, so this was just a fun diversion.
Brushed it off and gave it a matte clear coat and let it dry a while. There's some run spots but they will dry out.
Wiring the driver. I put two spades on the wire and used hot glue to secure them in addition to their clamping force just in case they wiggle free. This way they won't get free if it rattles around.
Drilled in some pilot holes through the driver in place so that it's exact. Then put in the 8 screws that will hold it in place. I didn't need anything for the hole since the cheap driver has enclosure side foam which was nice.
Driver is in place and secure. That top left run spot is ugly, but only shows up in the sun like this. Can't tell in a dark office room. Will clean better next time.
To control the driver I'm using the Dayton DSP-LF. It's a cheap $62 bluetooth DSP that has input and output. It uses the iWoofer app to control the interface and saves from there. You can make changes in the GUI and real time get the effect without waiting for it to save. Took a minute to learn how to do lowpass, highpass and add PEQ filters, but once I figured it out it was much easier to use and quite nice. I wish it went lower than 20hz but that's ok since this enclosure isn't going to do anything below 20hz anyways.
Here's how the GUI looks in iWoofer for the DSP-LF. I had to drop the 40~50hz range here to account for some room gain and set steep 48db/oct lowpass and highpass filters so the driver only played in its range.
I did some near field sweeps to get an idea of what it was doing to try and see the driver and enclosure interaction and output with as minimal room influence as I could since I didn't want to put this on a 6 foot ladder outside nor do I have an anechoic chamber. So just a quick near field measurement after some DSP work to flatten it out.
Here's the REW sweep. The Y axis is 1db intervals. 20hz is 93db here, 21hz is around 96db (and perhaps close to it's F3 in this setup). The rest is between 99~100db so only 1db variation from 25hz to 80hz. Pretty flat! No smoothing applied. But again keep in mind this is not perfectly accurate, this was a near field measurement.
I later re-did my DSP values and EQ for actual in room response to get it close to this. Not quite this, but similar enough. And it sounds great so far. No port noise at all at 107~108db just testing and tuned it back down. I listen around 95~98db max I find via SPL measurements while listening.
Tucked under the desk and integrating with my Philharmonic monitors that I built (got pre-made cabinets though, now wishing I build those from scratch).
Thanks for reading this far.
Very best,
The final clamping from the front. After this it's finishing and testing.
Here's some messy examples of the wood filler paste. I just slapped it into place over all the counter sunk screw heads and filled in any major gaps or imperfections where I joined the boards together after I sanded things a little to fit best.
Sanding the enclosure. On the left I have no sanded yet so you can see the messy wood filler paste. On the right you can see where I sanded just so you can see what it looks like after filling in screw holes. You can see them of course, but they're smooth and no metal showing.
This part wasn't needed, but I have an old router and a 3/8th inch round over bit I already had. I just did the edges to get a rounded edge and corners. Not hard to do. Wish I had a hand trimmer instead for this kind of work. Might pick one up. This thing is overkill for this. I like this natural look. I almost left it like this and was just going to seal it. But it would look too bright in my shabby dark old office area and rarely be seen anyways.
Testing some dark walnut stain on the bottom of the box. You can see where I didn't clean up some glue. It's the bottom, so that's fine.
Stained the whole cabinet. Darker than I wanted in reality. I tested another piece and sanded it and didn't like how that worked, so I left it alone. Next time I'll go a little lighter on the stain. I think I would have liked half this darkness maybe. Still, not a problem, originally was going to just make it duratex black or something, so this was just a fun diversion.
Brushed it off and gave it a matte clear coat and let it dry a while. There's some run spots but they will dry out.
Wiring the driver. I put two spades on the wire and used hot glue to secure them in addition to their clamping force just in case they wiggle free. This way they won't get free if it rattles around.
Drilled in some pilot holes through the driver in place so that it's exact. Then put in the 8 screws that will hold it in place. I didn't need anything for the hole since the cheap driver has enclosure side foam which was nice.
Driver is in place and secure. That top left run spot is ugly, but only shows up in the sun like this. Can't tell in a dark office room. Will clean better next time.
To control the driver I'm using the Dayton DSP-LF. It's a cheap $62 bluetooth DSP that has input and output. It uses the iWoofer app to control the interface and saves from there. You can make changes in the GUI and real time get the effect without waiting for it to save. Took a minute to learn how to do lowpass, highpass and add PEQ filters, but once I figured it out it was much easier to use and quite nice. I wish it went lower than 20hz but that's ok since this enclosure isn't going to do anything below 20hz anyways.
Here's how the GUI looks in iWoofer for the DSP-LF. I had to drop the 40~50hz range here to account for some room gain and set steep 48db/oct lowpass and highpass filters so the driver only played in its range.
I did some near field sweeps to get an idea of what it was doing to try and see the driver and enclosure interaction and output with as minimal room influence as I could since I didn't want to put this on a 6 foot ladder outside nor do I have an anechoic chamber. So just a quick near field measurement after some DSP work to flatten it out.
Here's the REW sweep. The Y axis is 1db intervals. 20hz is 93db here, 21hz is around 96db (and perhaps close to it's F3 in this setup). The rest is between 99~100db so only 1db variation from 25hz to 80hz. Pretty flat! No smoothing applied. But again keep in mind this is not perfectly accurate, this was a near field measurement.
I later re-did my DSP values and EQ for actual in room response to get it close to this. Not quite this, but similar enough. And it sounds great so far. No port noise at all at 107~108db just testing and tuned it back down. I listen around 95~98db max I find via SPL measurements while listening.
Tucked under the desk and integrating with my Philharmonic monitors that I built (got pre-made cabinets though, now wishing I build those from scratch).
Thanks for reading this far.
Very best,
You can use some website for file sharing, and on this way other people also can use the file for other projects!
Does the box make strange/intersting noises at a few notes/freqs ? (I dont mean chuffing) I keep messing with super long/kinda small ports (in qw pipes) and sometimes there’s some interesting things to hear nearfield at decent output levels (not chuffing) .
I think I can share it here, see if this works. This is the basic model with the driver embedded so you can play around with different stuff. Filters are disabled so you can set your own or see some suggestions if they carry over.
I've attached it with the container file name *.txt
Just remove the .txt from the end so its .wpr and it should work.
Very best,
If the port is undersized for area, it will have compression. I don't hear weird noises on any of the ports I've done on several bass reflex subs I have. I model the ports to have area to allow 18m/s or less air velocity with full signal applied. Or whatever signal you plan to use.
With a few builds, any noises were primarily leaks or vibrating problems with something that was loose.
Very best,
Keep in mind WinISD doesn't calculate slot ports correctly, so the model I sent you has the pipe port modeled for 18m/s air velocity. You can manually convert this to a slot port with 2.227 end correction factor. Just take the diameter of the pipe port that is already modeled in WInISD in the model, and use the right end correction factor for slots (2.227) and calculate the new length from that:
http://www.calculatoredge.com/new/ventlength.htm#length
Then to figure the slot port dimensions, you take the pipe diameter area and divide it into your box dimensions. Example, 5.2 inch diameter is an area of 21.3 square inches. If your box was using 3/4th inch thick material and was 16" total width, the slot width could be 16" - 1.5" or 14.5" total width. So the slot would be 21.3 square inches divided by 14.5 inches = 1.46 inches height. The slot would be 1.46" height, 14.5" inches wide and the length is what was calculated from the link above with the right end correction value. Simply adjust the dimensions based on your actual dimensions and use the logic of converting from the diameter area.
Very best,