# Natalie P towers, with a twist



## mrstampe

After a lot of reading and advice from fellow Shacksters, I’ve decided to start out my 5.1 DIY surround with a set of Natalie P floor standing left and right channels. Eventually, these may move to the rear if I decide to build Dayton TMWWs for L/R and a Dayton WTMW center. Also, an SDX15 sub is in the works. 

I plan to build the ported 50L version of the Nat Ps, but I’d like to put a twist on the design… or maybe a bend. I’m reasonably experienced in woodworking, though this would be my first try at panel bending. This can be accomplished by form pressing thin laminates into thicker panels, by saw-scoring MDF or Baltic Birch, by stacking “polylam” walls, or buying manufactured bendable ply. I'm not married to these plans, so I am open to creative ideas other than the standard rectangle.


See a few sketchup ideas at the end.


Bending techniques…

form bending









scored









bendable ply









translam











Questions:

1) The Swerve preserves the intended Nat P baffle dimensions, but the Vibe and the Wave are instead widen to 10” on average with curved edges. Will this affect the sonic qualities of the speaker?
2) Does anyone have experience with these bending techniques? Any advice?
3) Some building the 50L towers seem to prefer a higher tune (6” long, 3” diameter port = ? tune) to the designers recommendation of an 11” long, 3” diameter port for a 28Hz tune. Any thoughts on that?
4) Which design do you prefer?


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## BoomieMCT

Keep us posted on this. I love curved cabinets! I think one of the pictures you posted was cut in layers and glued, not bend wood.

As far as the baffles - making wider baffles will lower the point where baffle loss begins and may affect your crossover. This is not too hard to compensate for in the crossover with a little patience.

Also, I think the "wave" is the best design - but they all look great!


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## ktaillon

I like the wave the best also! I've been thinking about curved sides also, I was planning on using multiple thin (1/4) pieces of plywood.

I also through together a rounded back speaker..










Here's a different shape speaker, I just started work on these.









Or here is one that I haven't built yet(the wife thing)










You can see other pics at the link below...


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## Anthony

Cool designs. Keep us posted. (sorry I have nothing else to offer in terms of insight here  )


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## mlwebb

re tuning, I just finished a pair with JonM's original crossovers (otherwise same speaker as the Nat P's, also 50 l towers, and I started with 3" precision ports with a 7" length (plus flare allowance), which according to winISD is a tuning of 34hz (not incl room) and they sound great. I am going to try a little shorter, 6-6.5 and see if it brings the 40-50 hz spl up a little.


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## mrstampe

mlwebb said:


> re tuning, I just finished a pair with JonM's original crossovers (otherwise same speaker as the Nat P's, also 50 l towers, and I started with 3" precision ports with a 7" length (plus flare allowance), which according to winISD is a tuning of 34hz (not incl room) and they sound great. I am going to try a little shorter, 6-6.5 and see if it brings the 40-50 hz spl up a little.


Hey Michael, welcome to the Shack! You'll find some great discussions here with impressively knowledgible people. Regarding your Natalie P towers, we'd love to see them. You could either post a quick photo in this thread, or even better, you could start a new thread describing your goals, building process, several pics of its progression and your impressions of the outcome. It would also be interesting to get your evaluation of how the Nat P changes by increasing the tune (shortening the port). Thanks for joining my build discussion, and I'll look forward to seeing you around the Shack!


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## Rodny Alvarez

I like the wave, :T

The bendable plywood would be the easiest to build, they have two types of bendable, so make sure you get the right one (birch bendable plywood)


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## bonehead848

Wave FTW! The bendable ply would be the easiest but these high level mtm builds really can throw out a lot of bass. Is braced bendable ply really strong enough?


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## mlwebb

Well, I tried the six vs seven inch port, (36hz, vs 34hz box tuning), and listening to a few single tracks (from Acoustic Alchemy to Rolling Stones sympathy for the devil, a couple beatles tunes, a country song (Fred Eaglesmith) and a little Joe Cocker), with sub off, no measurement equip but old ears, and I think I'll stick with the six inch port for a while. It seems to give a little more umph to the bass drum, guitar low notes. I think Jon originally tuned the smaller box version to 32-33 hz, so its worth trying a few port lengths to see what works with your room, and whether a sub will be used. They go very loud comfortably, not that I really crank them often, and sound very good. Sure you will be happy with yours 

Here's a picture of mine, design(pdf) and finished(jpg)
http://www.mlwebb.com/pdf/mtm2f.pdf



I consider myself a pretty experienced woodworker (new to speakerbuilding), and as for curves, the stack laminating looks bulletproof, but an awful lot of work, absent a cnc. My vote would go for making your braces the permanent form for laminating two or three layers of bending ply, with titebond III, a narrow crown air stapler, and a paint roller for gluing the laminations. And watch how tight of radius your trying to bend, I've had my share of glue up madness, when the wood won't behave, the glue is drying, the clamps are all wrong somehow.... 

For curves, I like to draw them in a vector illustration program, and print them out fullsize for templates, not just for construction ease, but it is easier to get a curve that will bend naturally. 

I will be interested in watching your progress.


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## mrstampe

Hey michael, that's a great looking speaker!

I think I'm leaning toward the Nat P Wave and possibly done in verticle polylam layout. In that case, the finish would be polyurethane over BB verticle layers on the wavy sides and a nice complementary veneer on the baffle. I just wonder if all of those verticle wavy lines would accentuate the curves or be too distracting? If I'm not going to see the polylam layers, I may opt for one of the other methods.

Rough dimensions would be as follows: H40" x W10" x D12", curve wavelength 20" and amplitude 1/2" --> If the sidewall were a soundwave, that corresponds to a audio frequency of 675Hz! Also an internal volume of 56L before driver, bracing and port subtraction.

Also, a higher tune or even a sealed enclosure for the mains may be easier to mate with that SDX15 sub in the planning stages. Any suggestions as to how best to tune and cross mains to the sub?

Thanks for all of the advice!


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## jeremy7

great thread. I also vote for the wave. Ive never built any curved speakers, but have been putting a lot of thought into it lately. Im curious if the curved sides on the inside will also help with internal standing waves.


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## mrstampe

Insulating the cabinet should aleviate most standing waves, but if any are left, the continuously waving sidewalls are still "in phase" with each other and technically still parallel. The front-to-rear standing waves will likely still be the most prominent, if any.


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## Geoff St. Germain

As far as building techniques for curved cabinets, here are my thoughts. I've done what is basically form bending and built up the sides using 1/8" MDF to 3/4" total thickness. This technique is a lot of work, but not as much as the translam technique. Translam is good is you don't mind all the work and all of the waste. You could use it to make more complex curves more easily, though I don't know how well it would work for this project. Scoring is an interesting technique. I've tried it and will be using it on the towers I'll be building in the spring. Issues with the technique are that there is a risk of the thin areas breaking as well as the material developing more of a series of bends look to it rather than a continuous curve. When I do it, I'll probably do a 5/8" scoring and then overlay a piece of 1/8" MDF.


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## DRB

Wow, my Natalies are just run-of-the-mill rectangular solids. I wish I had more skill and patience. :no:


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## mrstampe

I've been out of town for a while, and work/military obligations will keep me busy for the next week or so. After that, the Nat P Wave project will begin. Any additional advice before I start?


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## DRB

> I've been out of town for a while, and work/military obligations will keep me busy for the next week or so. After that, the Nat P Wave project will begin. Any additional advice before I start?


Measure twice, cut once? :innocent:

Good luck. Even though mine don't look great, they sound good to me.


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## Sprtex

Hey Ray,

Could you start a new thread with pics of your Nat P's? A lot of us are no where near the level as Mark and others where carpentry skills are concerned, and we could probably learn a lot from your design and finish. I'd like to see your work if you have time to post it.

Mark, let me know what I can do to help you with your build when you're back from training.

Tony


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## DRB

> we could probably learn a lot from your design and finish.


Things to be learned from my Natalie P's:

1)You need proper tools. Power saws are essential. MDF and jig saws are not real friendly.

2)Laminate, like paint, will not hide all flaws under it.

3)Bondo is your friend.

4)Hand sanding sucks. It is not a replacement for 1).

My Nat's are structurally sound and they sound good. But they are lacking in the beauty department. The fact that they are all black makes them look like those slabs in "2001: A Space Odyssey".


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## bonehead848

DRB said:


> 4)Hand sanding sucks. It is not a replacement for 1).


HAHA, I learned the same thing after my first build!


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## Exocer

Very nice! I wish i had gone with the curved sides myself...


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## mrstampe

*The Natlie P Wave build begins!!*

To summarize the final build plan:
Design: Natalie P MTM
Cabinet: floor standing 50 liter (10" x 12" x 40" exterior)
Waves: wavy sidewalls formed with bendable ply
Port tuning: to be determined
Prefinish: Bondo seams and open grain, sand and seal
Finish: piano black lacquer (if I can figure it out)


*Step 1: transfer waves to template*
I laid out verticle lines for front baffle and rear wall on 1/4" hardboard as follows: midline left to midline right margins 8 1/2", as well as 1/2" deviation line to left and 0.5" deviation to right for both walls. Then at 5" intervals, I marked out points along the wave at left dev line --> midline --> right dev line --> midline, and so on. Finally, I used an adjustable ship curve tool ($20 at Rockler.com) to trace the curves based on the layout points. (this will all become clearer in the Step 3 picture)











*Step 2: cut out template*
Since my bandsaw conveniently fried just before this project began, I resorted to my jigsaw -- very slow going and not as accurate, but it gave me a decent rough result. I then sanded to my lines using a drillpress drum-sanding kit ($12 at Rockler.com).











*Step 3: transfer template to 3/4" MDF, cut*
I applied my template to MDF board with double-sided tape, traced the outline, and cut out by jigsaw. Since I already had a relatively smooth template curve, there was no need for sanding. I just used a bearing-guided flush router bit on a router table. The bearing moves smoothly along the template, while the flush bit duplicates the curve in the MDF baffles.


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## DRB

Having the right tools (and knowing how to use them) is everything. I suggest you continue to document your progress for the edification of others.


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## JCD

:yeahthat: only times 100.. I can't wait to see how this unfolds!

JCD


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## jr1414

Can't wait to see how these turn out. Please keep updating.


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## mrstampe

*Step 4: baffle driver cut-outs*
I laid out the driver midpoints on each baffle based on the original designer's plans on HTguide.com:











Then using my handheld router with a Jasper circle jig, a pin placed in the desired radius jig hole and also into the midpoint of each driver location. Mounting plate recesses are routed first. Then, the cutouts are are routed through the baffles. The appropriate router bit for this operation is called a spiral upcut -- best source: MLCS.


















Here's how they turned out...


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## Ricci

Really interested to see how you construct the bends of the side panels. Can you explain it? Looks like it's going to be very challenging.


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## jr1414

From what I remember, he will be using bendable plywood for the sides, with the front and rear baffles acting as a form to bend them over. Bendable plywood is pretty neat stuff, although not inexpensive by any means.


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## mrstampe

[BANANA]what he said[/BANANA]


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## Ricci

Will it relax into the curvature of the baffles over time, or will the ply tend to want to straighten out? Just wondering.


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## mrstampe

Bendable plywood is very compliant and can be purchased in two varieties -- one that bends on the long/verticle axis of a 4'x8' sheet, and the other bends on the short/horizontal axis. Its construction is based on a flexible wood core (unknown type) and exterior laminated layers oriented horizontally if bending horizontally; vertically, if bending vertically.

I bought the horizontally bendable 3/8" ply at $33 per 4'x8' sheet. So as jr1414 described, the front baffle and rear wall will serve as forms to which the very flexible bendable ply will be glued and tacked with pneumatic staples. The ply will take almost whatever shape I give it and will remain solidly in place by being fixed to the MDF front and rear forms. Each side will require two 3/8" sheets with liberal glue for the entire mating surface of the ply sheets, so as to avoid resonant layers or airspaces. Since my side dimensions are 11 3/4" x 40", I can get 8 pieces out of one sheet of ply -- all in all, a pretty cheap way to go.

Keep in mind, this is a big experiment. I've never used this material before, but it should work.


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## Owen Bartley

Mark, very cool design ideas for this project. I'm interested to hear how the bendable ply is to work with and see how it all turns out. I've always really liked the multi-layer laminated idea, but it must cost a fortune, be a pain to do right, and waste a ton of material. Still, the integrated bracing must be incredible.


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## JCD

Ok, two things..

Most importantly, it's been FAR too long with out an update.. specifically with pictures.

Second is regards to the following statement you made:



> Then using my handheld router with a Jasper circle jig, a pin placed in the desired radius jig hole and also into the midpoint of each driver location. Mounting plate recesses are routed first. Then, the cutouts are are routed through the baffles. The appropriate router bit for this operation is called a spiral upcut -- best source: MLCS.


Why not a plunge cutting straight bit? Also, after reading the description on MLCS, I got turned around as to which would be better, a downard spiral vs the upward spiral. The upward gets rid of the debris, but the downward seems to be able to plunge better. Again, I got all turned around reading the difference between the two.

JCD


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## mrstampe

JCD said:


> Ok, two things..
> 
> Most importantly, it's been FAR too long with out an update.. specifically with pictures.


I couldn't agree more! I hope to apply the bendable sides to my front and rear face forms sometime this week. Keep an eye out for that.




> Second is regards to the following statement you made:
> 
> Why not a plunge cutting straight bit? Also, after reading the description on MLCS, I got turned around as to which would be better, a downard spiral vs the upward spiral. The upward gets rid of the debris, but the downward seems to be able to plunge better. Again, I got all turned around reading the difference between the two.
> 
> JCD


You can usually accomplish the same thing in woodworking with multiple different tools. In this case, I would recommend the first two of three bit choices:

*#1 Spiral Upcut bit *-- Best choice for this application for two reasons. As you noted, cut wood particles are ejected out of a dado recess (eg. recess for driver mounting lip) to avoid clogging . Also, it's designed to shave the wood as it cuts your form rather than cutting/chipping -- this is more important when duplicated hardwood forms from template, but never a bad idea. The finished surface tends to be smoother than when cut with choice #2.

*#2 Plunge cutting straight bit *-- Not a bad second choice if you're working with MDF or softer woods. This one is a rare bird, though. Most straight bits do not have the extra cutters on their ends to plunge. (MLCS comes through again) A standard straight bit will NOT work. The negatives are that it cuts/chips rather than shaves, and it does not direct debris out of the way.

*#3 Spiral Downcut bit *-- While it may be easier to control plunge speed through hardwood with the downcut (b/c the cutting edge opposes your downward plunge force, instead of self-feeding like the upcut), it can get choked on all the shavings that that are directing into your plunge hole. Okay for shallow routing, but not for deep plunging.

Hope that helps.


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## JCD

mrstampe said:


> *#1 Spiral Upcut bit *-- Best choice for this application for two reasons. As you noted, cut wood particles are ejected out of a dado recess (eg. recess for driver mounting lip) to avoid clogging . Also, it's designed to shave the wood as it cuts your form rather than cutting/chipping -- this is more important when duplicated hardwood forms from template, but never a bad idea. The finished surface tends to be smoother than when cut with choice #2.
> 
> *#2 Plunge cutting straight bit *-- Not a bad second choice if you're working with MDF or softer woods. This one is a rare bird, though. Most straight bits do not have the extra cutters on their ends to plunge. (MLCS comes through again) A standard straight bit will NOT work. The negatives are that it cuts/chips rather than shaves, and it does not direct debris out of the way.
> 
> *#3 Spiral Downcut bit *-- While it may be easier to control plunge speed through hardwood with the downcut (b/c the cutting edge opposes your downward plunge force, instead of self-feeding like the upcut), it can get choked on all the shavings that that are directing into your plunge hole. Okay for shallow routing, but not for deep plunging.
> 
> Hope that helps.


Thanks for the reply and detailed explanations! Before posting my question here, I had e-mailed MLCS with basically the same question. Their response was to use the spiral downcut -- however, based on your response, I don't think they took into account the "lip" required to flush mount the speaker.

I do have a follow up q for you if you have the time -- when you use the spiral upcut, do you have to drill a starter hole to the required depth first? Or can you plunge down adequately with the spiral upcut bit? Also, what size bit do you use?

Oh, and I'm an MDF guy if that changes any of your answers.

Thanks for the info and I can't WAIT to see how your project progresses.

JCD


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## mrstampe

JCD said:


> I do have a follow up q for you if you have the time -- when you use the spiral upcut, do you have to drill a starter hole to the required depth first? Or can you plunge down adequately with the spiral upcut bit? Also, what size bit do you use?
> 
> JCD



I used a 3/8" spiral upcut. No pilot hole is necessary, as this bit mimics a drill bit in its design. It was a compromise in size, having to be small enough to make a full-thickness bore in one pass and using the same bit for two shallow passes of different radii to form the lip. The 1/2" bit might have allowed one pass for the lip, but that's 33% more wood dust to throw around on the full-thickness cuts. Again, there's more than one way to skin this cat (so to speak).


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## mrstampe

Okay, I'm going to jump ahead a few steps, then come back to explain the details later...

I've wired the crossover boards and assembled one of the towers, except one of the wavy sides. I have to keep it open to stuff insulation, install the x-overs and to wire everything up. I've learned a lot from the first one, so the second one will go together much easier. That will be the one I chronicle step-by-step with pics.

Any thoughts or suggestions? Will I need post-assembly access to the x-over compartment? I'm open to any advice.


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## Anthony

Usually, the crossover is mounted in one of the driver sections, or a big cup/plate is used on the back so that the crossover can be pulled out. I've also seen fake bottoms with the crossover there, disguised as a stand -- just flip the speaker over to access it.

Hope this helps some.

Lookin' good!


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## Jason Schultz

I like how you've assembled the xo componants on the board. I will do mine like this next time.


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## mrstampe

*DAYTON REFERENCE SERIES DRIVERS ON SALE!!*
If you've considered building these Natalie Ps or other Dayton RS speakers, BUY NOW! PartsExpress has the major RS drivers marked 20% off this week only.

RS28A 1 1/4" aluminum tweeter $38 (reg $49)
RS180 7" shielded driver $33 (reg $41)
RS225 8" shielded driver $42 (reg $53)
and more...


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## jeremy7

thanks for the heads up mrstampe


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## keelay

Very nice job. I bet these make a statement in the Living Room. This might actually pass the wife test.

- KYle


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## bonehead848

any updates on this? Where are you mrstampe!


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## Owen Bartley

Yes, more updates please! I've been waiting to see a) how you did these, and b) how they turned out! They look great so far.


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## keelay

Let's Start Chanting together....

MORE!
MORE!
MORE!
.
.
.
.
MORE!




(please)


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## tcarcio

It never ceases to amaze me the skill some of you guy's have. Great looking desiegn and I will join in on the chant.....MORE,MORE,MORE........:yes:


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## mrstampe

The chants have been heard!! I've been otherwise occupied by for the past few months, but I'm really trying to find that 25th hour in the day to finish these Nat P Waves off. I'll do my best to explain the steps and document with pics. More to come very soon...


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## keelay

Hey, I know how it goes. I have a set of natalie p's in my living room. I got the drivers. Build the crossovers. Set them up to break in on an open backed piece of particle board that I had laying around. I just cut some holes to mount the drivers. I figured while they break in I'd build the enclosures. It's been a month now and still haven't had time to build my enclosures. Mine will be interesting, but not nearly as interesting as yours.

Kyle


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## fbov

Kyle, didn't you just finish a Triune LCR set, the one in your avatar? I take it that wasn't your living room with the corner HT set-up...
Frank


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## keelay

You're right. That was not my living room. I'm helping a good friend of mine with his HT project and construction. We reached a nice agreement where he buys the parts and materials and I build them. I was in the market for a replacement set of speakers for my HT in a box (Onkyo) and I was curious about whether I'd like the triunes or not. 

I do really like the triunes. Very balanced, nice open clear sound. They were far better than the HT-in-a-box that I had, which ultimately convinced my that the DIY route CAN produce significant results for the money. In the end I though I got curious about the Natalie P ravings. IF a set of $150 speakers sound that good, what would a $400 set sound like. You know how it goes. 

Kyle


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## fbov

Kyle, 
I suspect that the major benefit of NatPs' over Triunes is max SPL and minimum frequency. You've got 5x higher Vd from the RS180s, 4x more parts in the XO, 2x greater power handling, and 15Hz lower resonant frequency. That said, they won't sound nearly that much better unless you're finding the Triunes defficient in one of these areas. Your first DIYs nearly always sound better than anything else you build after.
HAve fun,
Frank


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## keelay

fbov said:


> Kyle,
> I suspect that the major benefit of NatPs' over Triunes is max SPL and minimum frequency. You've got 5x higher Vd from the RS180s, 4x more parts in the XO, 2x greater power handling, and 15Hz lower resonant frequency. That said, they won't sound nearly that much better unless you're finding the Triunes defficient in one of these areas. Your first DIYs nearly always sound better than anything else you build after.
> HAve fun,
> Frank


Yeah, Add to that more linear response and lower distortion. Even with them mounted to my "break in board" I can tell the difference in clarity. Female voices, male voices, drums, symbols - everything is distinctly more accurate on the Nat P's. Once I build my enclosures I'll get to experience that lower realm that you were mentioning. 

Kyle


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## HSV HTGuy

Hope you let us know if you find significant listening improvement between the 100 and 400 dollar sets. Appears from the thread you can set up both and actually do an A/B switch comparison. I find it hard to "remember" subtle differences if there's any timelag between listening sessions.


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## mrstampe

*The next step I took with the first Nat P was to prep the driver holes and set them up with T-nuts and bolts, then I stapled a double layer of 5/8" carpet padding to all interior walls. Hey, I know it's unconventional. We just had our carpet replaced, so I thought I'd give it a try.*


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## windforce2009

How did you end up liking the carpet pad? Seems like a pretty good idea, its usually fairly dense, and tends to not break down as fast as conventional foam.


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## keelay

windforce2009 said:


> How did you end up liking the carpet pad? Seems like a pretty good idea, its usually fairly dense, and tends to not break down as fast as conventional foam.


Foam works reasonably well. There are better materials. Better meaning more sound damping per volume. But when it's this cheap it doesn't really matter especially if you already have some laying around. What ever foam you use isn't going to "break down". Inside an enclosure it will last for several decades at least.

Kyle


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## windforce2009

I must admit that in the speaker systems I have built I use Black Hole 5 and poly fill where needed. I know many people prefer to use cheaper material. The double carpet pad idea I found inventive.

As far a foam breaking down goes, my comments were based on foam breaking down exposed to sunlight, but inside an enclosure thats not going to be a problem.


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## mrstampe

*We'll see how it works... I can still stuff with polyfill if what I have isn't enough.

This project has been drawn out way too long!! Last week I glued up the final wavy wall to the second speaker, used bondo on small gaps along the baffles, sanded, and primed. Today, I'm painting driver recesses, the back and the bottom with satin black. I might even get started on the veneer -- highly figured makore (african cherry wood). Will post photos soon. I'm really looking forward to finishing them off and finally get to enjoy them in the theater. *


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## mrstampe

*Pictures as promised... Painting and veneering have been delayed once more, but hopefully by no more than a week. This project contains a series of firsts for me -- veneering is the only thing that has me a bit intimidated. I just plan to use one speaker to caul and clamp to the other when applying the veneer. I'll lay down adhesive, veneer, wax paper, a layer of my versatile carpet padding, then clamp the other speaker on top (for the wavy sides only). Please stop me if anyone sees a flaw in my plan.*


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