Build: 4x Ultralight 200mm Double Reverse cabs

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Seth
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Build: 4x Ultralight 200mm Double Reverse cabs

#1 Post by Seth »

Since I'm planning on going slightly outside the bounds of the plans, I chose to obscure the title of this thread a little bit so future readers don't get a false idea that what I'm building is in the plans. As usual, I'm probably overthinking it. But, that's why the title is what it is.

It's slightly premature to begin a build thread on these, but it just feels like the right time to put forth my intentions.

The intention of this build is to make the DR200 as light as reasonably possible without serious detriment to sound quality and/or sensitivity. I'll be using ¼" ply instead of ½" wherever possible and instead of the popular full/square back option, these will have exposed butt cheeks to further reduce weight. I've chosen a super light weight, 2.4 pound neo driver, the PRV Audio 8MB500v2-NDY, which is a discontinued item and no longer available. I bought 8 of these drivers back in 2018, along with nearly 100 piezo tweeters... man, I've been putting this build off for far too long. Anyway, this initial build will be four cabs, with melded arrays. I'll build the second set of 4 cabs at a later date.

I ran all the parts in MaxCut, the cut optimization program I use, and I think I'll be able to squeeze four of these cabs out of three 5x5 sheets of ¼" BB and two 4x8 sheets of 1/8" Poplar bendy ply (with a lot of bendy ply left over... Perhaps a Jack12 Lite is in my future too). So, I made that purchase today. In order to fit the lumber in my car, as well as make them more manageable on the table saw, I had them cut the 5x5 sheets down to roughly 20"x60" pieces and the 4x8 sheets down to roughly 19"x48" pieces. I've never used bendy ply before. It's way more flexible than I had envisioned it would be. Cool stuff. I look forward to learning to work with it. I was a little peaved that the local well known and respected specialty lumber yard had their ¼" BB ply stored the same way they do at lowes and HD... on two chocks with a deep bow in the whole stack! Oh well. Moving on. I'll just have to deal with it. (grumble grumble)
20210104_172246.jpg
I also put in an order through PartsExpress for all the crossover components and other bits 'n pieces today. The Eminence adjustable pole mounts really add to the cost of a project in a hurry! Buy once, cry once... I guess. :cry: Since these first 4 cabs will potentially be bottoms of 4 stacks of paired cabs, I got the adjustable pole mount for each one. Only for the bottoms of these cabs though. Standard top hats for the tops of the cabs.

As I'm going through this build, please point out any concerns or thoughts you have. One of the things I've been contemplating is additional side braces to adequately brace the thinner ¼" ply sides. The plans utilize one brace for ½" ply construction. I considered doing 2 braces spaced proportionately equivalent to the DR300, or even up to 4 braces which would achieve spacing equivalent to the internal brace spacing of the Jack12 Lite, of roughly 4" between braces. Obviously, fewer is lighter, more is increased rigidity and overall cab strength. Whichever solution I land on, they will be strategically cheese holed or trussed.

A couple other design considerations that I haven't come to a solid conclusion on yet are SpeakOn Jack and handle placement. Thinking a small enclosure, centered top to bottom on the back, in the butt crack, with two jacks, one aimed up (to the cab above) and one aimed down (to a/the cab below), along with one more on the top and bottom of the cab should be sufficient and fairly handy. Maybe even forego the one on top of the cab... Don't see much use for that location. As far as handles, I'm considering nice comfortable girthy handles glued across the valley of the butt cheeks, one at the top and a matching one at the bottom. Or, possibly a couple of strategically placed simple looped webbed straps instead, to minimize weight. Just something to make it easy to grab with a hand or two... or possibly grab two with one hand, maybe.

Anyway, happy to hear and discuss your thoughts along the way as the build comes together. If you've got a clever idea, please share it with me.

This will likely get started by midweek, next week.
Last edited by Seth on Tue Jan 05, 2021 2:25 am, edited 3 times in total.
Build in process - 2 WH6, one Alpha 6a loaded, one PRV Audio 6MB250-NDY loaded

Two 2x6 shorty SLA Pro's
One T39, 16", 3012LF loaded
Tall AutoTuba, 20" wide, 2x 8" MCM 55-2421
TruckTuba, 8½" wide, 2x 8" MCM 55-2421

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Tom Smit
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Re: Build: 4x Ultralight 200mm Double Reverse

#2 Post by Tom Smit »

It says in the plans to offset the side braces so that there are different path sizes. Perhaps 2 side braces per side, positioned to provide different path sizes would work (better than equal spacing) (?).
For the bottom cabs, would 1/4" be beefy enough for the tophats?
I covered the butt crack with a plate, put a hand-hold in the top and the bottom, and installed Speakons there as well. I really like the handholds this way.
TomS

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Seth
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Re: Build: 4x Ultralight 200mm Double Reverse

#3 Post by Seth »

Tom Smit wrote: Tue Jan 05, 2021 12:14 am It says in the plans to offset the side braces so that there are different path sizes. Perhaps 2 side braces per side, positioned to provide different path sizes would work (better than equal spacing) (?).
For the bottom cabs, would 1/4" be beefy enough for the tophats?
I covered the butt crack with a plate, put a hand-hold in the top and the bottom, and installed Speakons there as well. I really like the handholds this way.
Tom, I don't think I was aware you had made DR200's. Thanks for sharing the thoughts and experience.

That's a good thought, about the offset braces. I read that too. It's what inspired the thought of proportionately recreating the spacing used in the DR300 for a two brace per side configuration. Two braces averages out to about 5½" spacing between braces, not taking into account any intentional offset.

Also a good thought about top hat support. I'll give that a gander. I do like to route out and recess that sort of stuff instead of surface mounting them, which will obviously thin that area even further. But, I feel it gives the cab a professionally manufactured look/quality that I really appreciate. I'll have to give some thought to suitable backing and/or bracing. Fortunately, looking at the SketchUp, there's a bit of structure in that area to potentially contribute to the rigidity and stability of the pole mount, so maybe a backer will be enough, perhaps.(?)
Screenshot (85).png
Build in process - 2 WH6, one Alpha 6a loaded, one PRV Audio 6MB250-NDY loaded

Two 2x6 shorty SLA Pro's
One T39, 16", 3012LF loaded
Tall AutoTuba, 20" wide, 2x 8" MCM 55-2421
TruckTuba, 8½" wide, 2x 8" MCM 55-2421

Grant Bunter
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Re: Build: 4x Ultralight 200mm Double Reverse cabs

#4 Post by Grant Bunter »

Can I also recommend to build all 8 cabs together.
Load 4 with drivers and melded arrays initially, but any ply that bends doesn't do so forever without delaminating (don't ask me how I found out).

On a side note:
Why 4 with melded arrays? Is that for 2 rigs? If that's so, then that makes sense, but 6 of the 8 cabs with flat arrays (+the 2 melded) will ultimately weigh less...
Built:
DR 250: x 2 melded array, 2x CD horn, March 2012 plans.
T39's: 4 x 20" KL3010LF , 2 x 28" 3012LF.
WH8: x 6 with melded array wired series/parallel.
Bunter's Audio and Lighting "like"s would be most appreciated...

Ken Lustgarten
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Re: Build: 4x Ultralight 200mm Double Reverse cabs

#5 Post by Ken Lustgarten »

When you get one of these built I'll be curious as to what the weight savings is. I built my DR200's out of 1/2" Arauco which is a lot lighter then baltic birch. I will weigh one and post it here. Keep in mind that I do not have light weight neo drivers. Of course there is another way to lighten your cabs and get healthier in the process, hit the weight room :mrgreen:

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Seth
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Re: Build: 4x Ultralight 200mm Double Reverse cabs

#6 Post by Seth »

Grant Bunter wrote: Tue Jan 05, 2021 3:32 am Can I also recommend to build all 8 cabs together.
Load 4 with drivers and melded arrays initially, but any ply that bends doesn't do so forever without delaminating (don't ask me how I found out).

On a side note:
Why 4 with melded arrays? Is that for 2 rigs? If that's so, then that makes sense, but 6 of the 8 cabs with flat arrays (+the 2 melded) will ultimately weigh less...
Happy New Year Grant. Good to hear from you :thumbsup:

Bottom line on not building all 8 together is I don't have the funds. :broke:

You're right... the flat array would weigh about a pound less than a melded array. It would also reduce the build time and cut the build cost by about $20 per cab. I'm still contemplating how to do the second set of 4. To be honest, in spite of those benefits, I'm still considering building all 8 with melded arrays. Part of the consideration is the idea of having all the cabs be the same and not have to keep track of which ones are which when setting up, or finding a matching pair when I only use 2. The other thing that has me considering melded for all 8 is the SPL chart for the melded vs. flat array. The melded response looks better, even on axis. The point is certainly up for discussion and debate, although it wont be a pressing issue until I start the second round build... and who knows when that will actually happen.

But, to answer your question about why 4 with melded arrays... Some of the gigs I do, cover a very wide area (200+ feet) with the audience mostly tucked in close to that width, within 5-20' of the "stage". In the past, I've set up 4 tops on poles spaced 50-60 feet across that listening space. So, at least 4 with melded, to be the bottoms of those 4 placement positions. Ultimately, I think 4 cabs would probably cover that gig on their own and not need another 4 cabs. But, I've read that having at least 2 cabs together provides noticeable improvements in sound quality. So, the ultimate plan is to have a two stack for each of those four positions.
Last edited by Seth on Tue Jan 05, 2021 12:14 pm, edited 2 times in total.
Build in process - 2 WH6, one Alpha 6a loaded, one PRV Audio 6MB250-NDY loaded

Two 2x6 shorty SLA Pro's
One T39, 16", 3012LF loaded
Tall AutoTuba, 20" wide, 2x 8" MCM 55-2421
TruckTuba, 8½" wide, 2x 8" MCM 55-2421

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Seth
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Re: Build: 4x Ultralight 200mm Double Reverse cabs

#7 Post by Seth »

Ken Lustgarten wrote: Tue Jan 05, 2021 11:46 am When you get one of these built I'll be curious as to what the weight savings is. I built my DR200's out of 1/2" Arauco which is a lot lighter then baltic birch. I will weigh one and post it here. Keep in mind that I do not have light weight neo drivers. Of course there is another way to lighten your cabs and get healthier in the process, hit the weight room :mrgreen:
Please do post the weight of your DR200's Ken. That would be great to have a real world comparison. The sales page says "...Measuring less than 20 inches cubed, and weighing in at less than 30 pounds..." I'm hoping to get these as close to 20 pounds as is reasonably possible, if not slightly less.
Build in process - 2 WH6, one Alpha 6a loaded, one PRV Audio 6MB250-NDY loaded

Two 2x6 shorty SLA Pro's
One T39, 16", 3012LF loaded
Tall AutoTuba, 20" wide, 2x 8" MCM 55-2421
TruckTuba, 8½" wide, 2x 8" MCM 55-2421

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Strange Kevin
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Re: Build: 4x Ultralight 200mm Double Reverse cabs

#8 Post by Strange Kevin »

I swear my Dr200s were closer to 40lbs but I had the full backs on them with 11 pound drivers!! (Delta pro 8b)

I'll be following this thread closely as I've been missing the DRs.
Its kinda funny, the DR250s may almost be easier to build lightweight as you have more 10" Neo-Driver options than the 8" lineup.

Regarding the offset braces, I believe that has to do with internal reflections. Once you "Swiss cheese" the braces, it may not be an issue..
Authorized Builder - Phoenix AZ.
Main Rig - 6 DR200s - 6 T48s (30")
SLA Pros for the smaller stuff.

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Tom Smit
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Re: Build: 4x Ultralight 200mm Double Reverse

#9 Post by Tom Smit »

Seth wrote: Tue Jan 05, 2021 12:46 am Tom, I don't think I was aware you had made DR200's. Thanks for sharing the thoughts and experience.
I have a pair of DR250 that I made in the back yard on the hood of a retired Volvo wagon...many years ago.


Seth wrote: Tue Jan 05, 2021 12:46 amFortunately, looking at the SketchUp, there's a bit of structure in that area to potentially contribute to the rigidity and stability of the pole mount, so maybe a backer will be enough, perhaps.(?)
Perhaps a plate as big as that floor is inside the woofer compartment may be enough. Hopefully it won't affect the tuning significantly or the port tuning, but, I don't know the answer to that.
TomS

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Seth
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Re: Build: 4x Ultralight 200mm Double Reverse cabs

#10 Post by Seth »

Strange Kevin wrote: Tue Jan 05, 2021 8:37 pm I swear my Dr200s were closer to 40lbs but I had the full backs on them with 11 pound drivers!! (Delta pro 8b)

I'll be following this thread closely as I've been missing the DRs.
Its kinda funny, the DR250s may almost be easier to build lightweight as you have more 10" Neo-Driver options than the 8" lineup.

Regarding the offset braces, I believe that has to do with internal reflections. Once you "Swiss cheese" the braces, it may not be an issue..
That's a good point about the DR250 and driver selection. As far as I can tell, the neo drivers I have are the only one's close enough to spec to use in a DR200. I haven't been able to find any others that are suitable. Not to say they don't exist... I just haven't seen them yet. Matter of fact, the only reason I became aware of this driver is someone asked about it's suitability in one of the threads.

I took a quick look at what's available in a 10" neo driver on PE. Unfortunately, the 3010MB mentioned in my copy of the DR250 plans as the ultra premium driver is apparently discontinued. The S2010 is an option, and the Deltalite II 2510... Took a look at the B&C 10CL51 and thought to myself that that would be the one I'd choose, but then I noticed the Vas was slightly too low at 36L (spec is 50-100L). 2.6 pounds for a 10" driver is pretty awesome and 5.5mm Xmax as well as the price isn't too bad either... oh well. At 3.5 pounds, the S2010 could be a candidate. Seems like all the fancy aluminum frame drivers are all at least twice the weight of the stamped steel basket drivers and for the most part, near or over $200 each.

I'd have to double check to be sure, but I think I paid something like $55/driver for the ones I have. I estimate my DR200 cabinets will cost roughly $150ish each, all said and done, complete with hardware and paint. Maybe slightly more if I add up every little related expense... glue, filler, sandpaper, paintbrushes/rollers. brads, and all the other incidental consumables. Really a smoking good deal, all things considered.

Do you not have your DR200's any longer?
Last edited by Seth on Thu Jan 07, 2021 2:16 am, edited 2 times in total.
Build in process - 2 WH6, one Alpha 6a loaded, one PRV Audio 6MB250-NDY loaded

Two 2x6 shorty SLA Pro's
One T39, 16", 3012LF loaded
Tall AutoTuba, 20" wide, 2x 8" MCM 55-2421
TruckTuba, 8½" wide, 2x 8" MCM 55-2421

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Seth
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Re: Build: 4x Ultralight 200mm Double Reverse

#11 Post by Seth »

Tom Smit wrote: Tue Jan 05, 2021 9:45 pm I have a pair of DR250 that I made in the back yard on the hood of a retired Volvo wagon...many years ago.
Tom, I like your style. Do you still have the Volvo?
Build in process - 2 WH6, one Alpha 6a loaded, one PRV Audio 6MB250-NDY loaded

Two 2x6 shorty SLA Pro's
One T39, 16", 3012LF loaded
Tall AutoTuba, 20" wide, 2x 8" MCM 55-2421
TruckTuba, 8½" wide, 2x 8" MCM 55-2421

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Seth
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Re: Build: 4x Ultralight 200mm Double Reverse cabs

#12 Post by Seth »

Looks like my estimate was a little shy. Probably closer to $200/cab for this build. Without the adjustable top hats and melded array, the cost comes down closer to $150/cab.
Screenshot (86).png
Build in process - 2 WH6, one Alpha 6a loaded, one PRV Audio 6MB250-NDY loaded

Two 2x6 shorty SLA Pro's
One T39, 16", 3012LF loaded
Tall AutoTuba, 20" wide, 2x 8" MCM 55-2421
TruckTuba, 8½" wide, 2x 8" MCM 55-2421

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Tom Smit
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Re: Build: 4x Ultralight 200mm Double Reverse

#13 Post by Tom Smit »

Seth wrote: Wed Jan 06, 2021 2:49 am
Tom Smit wrote: Tue Jan 05, 2021 9:45 pm I have a pair of DR250 that I made in the back yard on the hood of a retired Volvo wagon...many years ago.
Tom, I like your style. Do you still have the Volvo?
I do. It was a parts car, but I don't have any Volvos anymore. The plan is that it gets removed from the back yard THIS year (I've been meaning to, for the last couple of years :oops: )
TomS

Rich4349
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Re: Build: 4x Ultralight 200mm Double Reverse cabs

#14 Post by Rich4349 »

Was it a P1800ES?
2 DR250s, 2 27" Lab15 T-60s, 2 30" Neo Titan 39s, 1 Autotuba...and looking for more!

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Re: Build: 4x Ultralight 200mm Double Reverse cabs

#15 Post by Rich4349 »

Seth, I have some 1/2" thick state of the art (for 1960?) aircraft flooring, honeycomb design. It weighs 40% of 1/2" BB inch for inch. Think you could use a hunk for the bottoms of a couple of your cabinets?
2 DR250s, 2 27" Lab15 T-60s, 2 30" Neo Titan 39s, 1 Autotuba...and looking for more!

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