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GRS 8SW-4HE Little Beasts!

edited August 2023 in DIY

I scored one of these at the PE garage sale and threw it on the DATS V3. I'm still new to using the DATS but this is what I came up with:

Messing about in winISD. It is nice and sedate in .7cf sealed configuration (.707 Q F3 ~40hz), but with bass reflex/PR it will seriously unleash the beast! Seems hard to tame :o

Trying to use the Menards particle board shelving dimensions I managed a 13"x21"x11.5" box that encloses a quad stacked .75"x11.5" labyrinth slot port at the bottom (~44" total length) and ~.7cf enclosure volume after driver and plate amp volume. F3 27hz but nice and low sloped. At 135watts breaks past xmax at 20hz. 36hz and above over 102db at 1m.

Then I tried PRs. Sofar Ive gotten TWO 10" DS270-PRs to reach over 10mm excursion with a full 1lb (450gram) of added mass at an F3 of 24hz in 1cf. Will they even support that much weight?



  • That might be a bit much for the 270 PRs. The rss265PR should do it though.

    I've wondered about those and thought they'd be great....

  • edited August 2023

    @Wolf said:
    The rss265PR should do it though.

    At 3x the price though. $270 retail for driver and PRs, oof... I imagine factoring that in has got to open up other driver options?

    Since I've got the shelving boards and a plate amp from a previous tent sale, I might just try the labyrinth/folded slot port. Would be neat to try something other than just a basic box for once. And I just now realized I might be able to make all the cuts with my sliding miter saw instead of lugging the table saw out of the basement. B)

  • The 12" version are very, very nice subwoofers. I have no doubt the 8" will perform similarly.

    I have a signature.
  • edited August 2023

    Made some sawdust over lunch break today. I'd swear I measured the shelving boards at 11.5" actual but they really are 11.25". Still have to make a few recuts to adjust to that dimension.

    It may prove too restrictive with all the bends. So I'd call this an experiment. Used ~1-2/3 boards so technically the enclosure is less than $8 in material. I've wasted a lot more on "experiments" in the past. If it proves itself worthy I'm thinking of giving it the tuxedo t-shirt treatment.. Wood veneer on the front and black on the sides.

  • I have done the same thing with a slot port in a small box.
    Sounded pretty darn good, but I think I read that distortion is higher.
    I'll be that all the bends help squash port resonances.

    But Chahly - Stahkist don't want speakers that look good, Stahkist wants speakers that sound good!
  • edited August 2023

    Question for you guys concerning folded slot port design/build:

    Is it necessary to make all of the port walls as thick as the woofer enclosure?
    ie// - Can we not use thinner 1/4" panel material for the port walls/tunnel to conserve space/reduce overall cabinet dimentions?

  • Yes you can use 1/4" material for the port. I've also used it for mid enclosures and TL folds

     John H, btw forum has decided I don't get emails
  • edited August 2023

    I guess that makes sense. It is just providing a path for air mass being moved around by the air spring in the enclosure.

  • Yeah, some of that shelving is 11-1/2, some is 11-1/4. I always bring a tape measure with and pre-measure and select the 11-1/2 if available.

    Great looking build!

    I have a signature.
  • edited August 2023

    I measured all my stock just now. It is all 11.25". Don't know how 11.5" got stuck in my head. Only thing I can think is maybe I measured the top board in the stack at the store, but found it had damage so I set it aside for undamaged pieces. Oah well, it is my fault for not re-checking. I'll learn eventually, maybe.. probably not.

    I'll need to chop off .25" from the four port stack boards to maintain proper gap at the bends. So I lose around 1.75" port length overall. But the reduction in .25" port width drops the needed length by a little over 1" anyway. Regarding port length: I'm not trusting WinISD as I'm fairly sure it just assumes a port efficiency not well suited to slots. I found an online calculator that does at least have a specific slot port option to select and does output a shorter length than WinISD's calculation. So I'm trying that length. Fortunately it seems at such low tunings it takes a big length change to cause much of a swing.

    Then there is the loss of internal volume. The loss of .25" board width causes the internal volume to drop by about .1cf by my calculations. Fortunately the amp enclosure was a little smaller than my back-of-the-hand calculation so that gets me .05cf back. The rest of the lost spare volume I was allotting to driver and brace volume. I'd like to get that back. Sofar I'm thinking of making a spacer plate for the amp to bump it farther out of the enclosure.

    Funny enough right before I started making cuts an idea did wander through my head to maybe add .5"-1" to the height, just incase. But I didn't follow through.

  • edited August 2023

    So the plate amp I have is a Cerwin Vega ARPL88000. Listed for the V-10s ported 10" subwoofer. Cerwin vega's own manual rates the V-10s at 100watt rms/200watt max. But parts express rates the amp 100watt 8ohm, 200watt 4ohm. This seems strange. Cerwin Vega would leave that much power on the table by using an 8ohm driver?

    Further research hints they may have used the same plate amp in the V-12s that is rated for 150watt. So they may infact be using different impedance woofers to get different wattage ratings from the same amp. I struck out when trying to find true identical replacement drivers for the ohm rating.

    Unless I find other hard evidence, I'll have to assume it is 200watt rms at 4ohm and be careful with the gain knob.
    If it was actually 100watt at 4ohm I had thought of adjusting the cabinet design slightly for a little better extension at expense of power handling.

  • edited August 2023

    The picture shows the amp uses 230 watts. It won't be doing 200 watts into 4 ohms.


  • Dang you are right! By comparison the SA100 total usage rating is 210watts. Definitely telling.

    Now I have a decision to make..

  • edited August 2023

    So I decided to leave out one port stack layer. That bumps up the internal volume to about .94cf for ~.8cf after amp, driver and bracing. Due to the extra volume, shortening the port should only bump up the tune a couple hz at most, but ends up dropping estimated F3 a couple hz too. Hopefully there is some LF protection built into the amp since it was originally designed for a ported sub.

    I got the side profile glued up. Once I glue one side on the shims come out and braces go in. Since I didn't use the table saw, this glue up is going almost perfectly. ASMR type stuff! Man I reeealy need to get rid of that junky table saw.

  • Seems like a good compromise.

    From personal experience... when I had junky table saw I loathed the thought of and the process of cutting speaker panels. I just knew I was gonna be cussing at something that got screwed up. Now that I have a decent table saw with a very accurate fence I find cutting those same panels fun actually. Now if I could only figure out a way to make all my driver rebate router work like that........

  • edited August 2023

    Lol yep you describe my experience perfectly.

    My circle jig is literally a chunk of 1/2" plywood I screw to the router plate. I then spend many minutes trying to measure and accurately drill a hole in the plywood for a finishing nail as the pin. Initially I did OK with it, but it is only as accurate as I am and I've been growing tired of dealing with it (thus getting more sloppy). The bearing in my router is getting noisy so I'll probably re-evaluate and upgrade once it kicks the bucket.

  • Same router jig here Man. There was a super cool video someone posted of a totally adjustable diy router jig that looked slicker than snot. I need to find that again and build one for myself.

  • edited August 2023

    Yep was probably in that long shop gadgets thread. I'm just not a fan of "infinitely adjustable" stuff unless it can truly lock in place, since it can slip while you are using it and ruin the part (or part of you). Vibrations work their magic at loosening things easily if friction is all that is holding it in place.

    For me I really just need to trash the rotting shed at the end of our driveway and build a garage. Then I have a chance at some semblance of a workshop for real tools. But we had to get a home within city limits.. Oah lord the red tape... Though, my father often rubs elbows at the bar with one of the county engineers that oversees that stuff. So I might have access to inside intel to at least be able to navigate that red tape.

  • @PWRRYD said:
    Same router jig here Man. There was a super cool video someone posted of a totally adjustable diy router jig that looked slicker than snot. I need to find that again and build one for myself.

    And plz post it. My hand made board has sooo many holes I’m now needing to mark the correct hole with a red marker. And, although I measured twice… I had to go back and double tape the previously cut our circle (for my 8in woofer) and re- hone out about 1/32nd more to get the driver to fit- it worked - but geeze

  • Reach out to your realtor. Many times they know what can be done in a zoning area for garages and sheds. This can be a selling point for some. My realtor recently answered some questions I had about the matter.

    Good job on the sub build.

  • @tajanes said:

    @PWRRYD said:
    Same router jig here Man. There was a super cool video someone posted of a totally adjustable diy router jig that looked slicker than snot. I need to find that again and build one for myself.

    And plz post it. My hand made board has sooo many holes I’m now needing to mark the correct hole with a red marker. And, although I measured twice… I had to go back and double tape the previously cut our circle (for my 8in woofer) and re- hone out about 1/32nd more to get the driver to fit- it worked - but geeze

    I will post it. The one I'm thinking of had the router rotating on bearings so as you go round and round the cord and dust collection hose never twist up.

  • Nice find ! Thx

  • That's the one! Thanks for finding it.

  • I've built a small and large DIY circle jig. For things bigger than speakers (like a table) a large DIY jig is simple and a money saver. But I've decided my Jasper Jig (JJ) is well worth the money. I just looked when it came up in this thread and I see there is a JJ Pro that goes down to 1", which I may get because the standard one doesn't go below 2-1/4", which doesn't cover some ports and tweeters. But a JJ in 1/16" increments, with both a 1/4" cutting bit and a 9/16" straight bit allows you to cut precise cirecles in 1/32" increments from 2-1/4" (or 1") to 18".

  • I think you meant a 9/32" bit. :)

  • edited August 2023

    @Ed_Perkins said:
    I think you meant a 9/32" bit. :)

    Yes, thank you.
    And to give credit where credit is due, I got the idea of using the 9/32" bit with the Jasper Jig from a post of yours years ago.

  • edited August 2023

    I built my router circle jig with extraction that relies on the vacuum to keep the hose attached while running. It is also slip fit, so it rotates while in use. The Power cord, however, still twists. I also used a screw for the pin to hold the pivot in place during clockwise motion. You don't want that coming out! I also used aluminum 1" square stock for the Trammell, and this means I can change the Trammell for any length I want to use.

  • I definitely need to make an adjustable jig, but a mask along with seeing routing as a year-round outdoor sport simplifies my design / build.

  • edited August 2023

    It is together. Just gotta flush trim some of the edges and cut the driver hole. I have a basic grill shipping in tomorrow. Waiting for that to see if/how much to recess the driver. This thing Is chunky... I threw it on the bathroom scale and it came in at 29.2lb empty.

    The photo makes it seem big.. I guess it is for an 8" sub. But I bet it will dig more like a decent 10" and two could work as short stands for tall bookshelf speakers. Hoping I might be able to find a second one of the amps at a PE garage sale in the future. I saw one last time and was debating, but someone else claimed it before I could decide.

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