# Bamboo open baffle project almost done



## studiotech

Been workin on these for over a year now. Another few days and they will be assembled!


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## rhino2

Beautiful! Which drivers are you using? What is the back portion of the structure that the bamboo is attached to?


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## studiotech

rhino2 said:


> Beautiful! Which drivers are you using? What is the back portion of the structure that the bamboo is attached to?


Thanks so much. This project has been a real labor of love for me. I've been making various speaker projects for so long now, that it was time to make my own personal statement loudspeaker. About 2 years ago I made a large set of main monitors for the studio I work at and the project turned out so well, that I had the confidence to jump into this project. Those used Lambda 12M and Beyma TPL150 AMT style drivers.

The baffle was originaly planned as only 3 layers. Bamboo/MDF/Bamboo, with the bamboo to show on BOTH front and back. Baffle now have an additional rear layer of high quality plywood, so it's now at 3" thick.

Drivers are Raal, BG Neo10 and B&C 15ND. Support below 50Hz comes from a pair of sonotube style 15" Rythmik subwoofers. These are in heavy gauge PVC tubes rather than the carboard concrete form most everyone else uses. I'll get more picts up later today.

Greg


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## Zeitgeist

Looks great! Those might actually be the first pair of open baffle speakers that actually appeal to me!

Maybe because it's hard to dress up what's basically a flat piece of wood - but those look very stylish!

What are you using for EQ/amp?

You should post a picture of the studio monitors you built too


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## studiotech

All processing is built into the Digmoda units. EQ, Xover, B&O class D Ice amps. 

You can see the wire channel routed into the 2nd layer to allow for a nice clean look. 

Greg


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## studiotech

A pict of the Rythmik sub. Plywood mounting rings screwed directly to the wall of the PVC tube. It is .75" thick. Wrapped in a nice, tan vinyl.

Greg


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## hearingspecialist

very nice :T





Brian in Bakersfield...


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## studiotech

One ready to play....


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## studiotech

Better shots of the studio mains.


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## robbo266317

I really like the effort you went to route the wiring into the middle layer! It's the little touches that turn a good project into a great one. :TT


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## studiotech

robbo266317 said:


> I really like the effort you went to route the wiring into the middle layer! It's the little touches that turn a good project into a great one. :TT


Thank you. There are still a few things I would do different next time, but overall I am very happy with the results. Sometimes I get too anxious to get some work done and fail to plan ahead. For instance, had I planned on 4 layers from the begining rather than 3, I would have made the area directly behind the mids and tweets 2 layers thick instead of one. 

Performance related though, I am beyond words. It took so many tries to find the "right" midrange, I'm really just lucky that BG finally released the NEO10 just in time. I tried hi-eff fullrange, scan speak 15W, arrays of smaller drivers, metal, paper, poly ,you name it. I was literally a week away from buying some AE TD6 or Eighteen Sound drivers for the mids. AE magnet was so large, that I didn't really wanna use it for open baffle. It completely shielded the rear wave of the driver. There was something immediately special with the Neo10. Now, in my case, since I run 2 of them, they couple in their lower range and fill in the naturally rolled off response quite well, so that I don't really need any EQ to lowers the highs or boost the lows. Kind of like the way a 2.5 way system helps with BSC, but both are run through the entire midrange.

This whole project has been an adventure that started over 2 years ago with the studio monitors. I had enough confidence in myself after that to tackle my own personal reference project. From the very begining, I knew that I wanted to use the Raal. I had heard several systems with them at the RMAF2008 show and was sold. Great specs, effortless, natural sound that just seems to float in the air and the right sensitivity range that I wanted to be in. It was quite a nerve racking day at the bank sending a money order to Serbia to buy an order of them direct from Alexander at the factory. The lady at the bank thought that I had been sucked into some kind of online scheme! I assured her that it was legit and that I had met the guy in person. BTW, Alexander is one cool dude if you ever get to meet him at a hifi show.

Then I used the studio business ID to get some Digmoda direct too. Those 2 orders were alot of $ out there with nothing tested or prototyped yet! So I had a tweeter, had some amps/dsp ordered the AE Lambda 15 Dipoles and thought that all I had to do was find a mid. Never expected it too take so long. Then, on top of all that, I decided to change out the Lambda Dipole for a low Qts driver. That Lambda does amazing things for a single woofer on a relatively small open baffle, but once I decided to augment the low end with the Rythmik servos, the Dipole was kind of overkill for what I needed. The B&C worked out so well. It sounds super tight, clean and pitch defined down to about 50Hz, no problem. Adding the Rythmik just brought back that sense of visceral impact that I was missing with pure open baffle. I think I would have needed far more Dipole 15 to really ever get that same sense of slam.

Greg


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## Navydoc

Wow, those are really nice!


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## studiotech

Blurry cell phone shot from the listening position. Obviously the old Celestion SL600s are going away as well as the Maggie center channel way up on the TV. New center is a BG model with the same Neo10 driver and a Neo3 coaxially mounted. This will go under the TV once I make the new equipment rack. Should have sound tomorrow night once I get the Speakon NL8 wired up on the amp side and make new jumpers to connect the Rythmik plate and to the thu on the Digmodas.

Greg


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## Owen Bartley

Wow, studiotech... really nice work. The detail and effort you put into those speakers is very impressive, and I can only hope they sound as impressive as they look. Great job, and very tastefully done.


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## GranteedEV

Looks veryy Nice. What do the polars look like?


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## Zeitgeist

Looks good!

Thanks for posting the studio monitors and satisfying my curiosity. Glad to hear good things about the AE drivers, since they're what I'm using on my 3 way project..

I like the use of Speakons too!


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## studiotech

GranteedEV said:


> Looks veryy Nice. What do the polars look like?


From the prototype, admittedly the horizontal polars are not perfect, but the dip in response around the xover point is much more noticeable to the outside edges of the sofa. Once I get all settings finalized, I will post some measurements. The vertical window is relatively narrow due to the narrowed dispersion of the Raal in its highest range and the dual Neo10s at the top of their range, but the Raal foam pads help enough that anyone seated on the couch, whether short or tall, is OK. 

Greg


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## studiotech

Zeitgeist said:


> Looks good!
> 
> Thanks for posting the studio monitors and satisfying my curiosity. Glad to hear good things about the AE drivers, since they're what I'm using on my 3 way project..
> 
> I like the use of Speakons too!


Yeah, for 6 connections and prevention of an oops moment, Speakon is the way to go. That is, as long as you wire it right the first time. I checked myself several times, because I've got the connections at the amps output, both ends of the cable and then on the baffle, so 4 places I could have munched pretty bad. I doubled up on the woofer connections, so it runs off of terminals 1&2, + combined and - combined at the drivers terminals. Can't go wrong with a little extra AWG!

Ae are great woofers and definitely worth the price of admission if you gotta run a large woofer too high or want a SOTA 3 way.

Greg


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## GranteedEV

studiotech said:


> From the prototype, admittedly the horizontal polars are not perfect, but the dip in response around the xover point is much more noticeable to the outside edges of the sofa.


You should be able to maximize the horizontal response by using a steep crossover. Since the RAAL is to the side of the Neo10s that's probably your biggest source of lobing. With an FIR filter you could probably do 300db/octave with no issues, but even with traditional filters (which is what I think the digmoda uses) you should give 96db/octave a shot, at a frequency like 2.8khz (which the RAAL should be comfy with, I think). There's a lot of research that shows it's very difficult for us to hear the phase shift with these filters (especially after digital time alignment). By making it almost a brick wall filter, you'll make the off axis null really, really narrow - to the point where it would take some extremely critical listening to pick out. 

The vertical polars are of course going to be more difficult to do much about, although if you've got an extra amp channel for one of the Neo10s you can run one as a ".5" woofer instead of in parallel (or maybe throw in an inductor and equalize using the active crossover). I got the impression you were already doing that though so the preceeding might not be of much help; sorry.

All I can say is, having a digital active crossover makes speaker design fun, doesn't it?


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## studiotech

GranteedEV said:


> All I can say is, having a digital active crossover makes speaker design fun, doesn't it?


Yes, I've been only doing full active since those studio monitors. It allows so much optimization, that for anything other than small, modest bookshels, it is worth the price. A cheap Behringer DCX and an Emotiva multichannel amp is a lot of bang for the buck and allows anymore to totally customize their sound.

I will be sticking with the Digmoda for now, so I don't see FIR filters in my near future, but it's nice to know that as tech progresses, I have a clean upgrade path. That's part of the reason I went nuts with top notch drivers. I'm trying to keep them from being the limiting factor for quite a while.

Just the other day, a friend sent me a link for some refurbed, 4 channel Lab Gruppen amps with the Lake DSP processor built in......it is tempting, but I've got no more cash for this project at the moment. I'm sure it would be better than Digmoda, but I'm so thrilled with what I've already got, that I just need to be happy for a while before upgrades happen.

Greg


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## gorb

Those are beautiful. The cat is nice too


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## GranteedEV

studiotech said:


> I will be sticking with the Digmoda for now, so I don't see FIR filters in my near future, but it's nice to know that as tech progresses, I have a clean upgrade path. That's part of the reason I went nuts with top notch drivers. I'm trying to keep them from being the limiting factor for quite a while.


Do give 96db/octave a shot with the digmoda though. the amount these high order filters clean up crossover lobing is surprising noticible. :T


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## studiotech

GranteedEV said:


> Do give 96db/octave a shot with the digmoda though. the amount these high order filters clean up crossover lobing is surprising noticible. :T


Will do! Still dreaming of linear phase EQ and filters though.....

We did a test years ago at Bob Katz mastering studio with a Weiss digital EQ. Set a simple 10KHz shelf with 1dB boost in both linear phase and standard EQ modes. Flipped back and forth. The linear version preserved the transients of the signal better, while the regular version sounded like it slightly smeared the cymbals. Makes ya wonder....

Greg


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## studiotech

gorb said:


> Those are beautiful. The cat is nice too


Thanks. With three cats around, one of them is bound to be in the picture, but it always seems to be the same one. I guess he is my little audiophile!

Greg


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## gvimhoof

Beautiful work!


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## StereoClarity

Very nice work. I've been considering an OB project as well with the Neo10. Two questions for you.

1) How did you source the bamboo ply and how outrageous was the pricing?
2) What did you use to coat the rear and sides of the baffle?


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## studiotech

StereoClarity said:


> Very nice work. I've been considering an OB project as well with the Neo10. Two questions for you.
> 
> 1) How did you source the bamboo ply and how outrageous was the pricing?
> 2) What did you use to coat the rear and sides of the baffle?


http://www.calibamboo.com/bambooplywood.html

and

http://www.rustoleum.com/CBGProduct.asp?pid=31


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## studiotech

A few more of the sub portion of the build:


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## StereoClarity

That's a great finish with the rustoleum. Quite impressive.

That Bamboo ply is more reasonable than I thought. How much was it per sheet after shipping if you don't mind me asking.


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## studiotech

StereoClarity said:


> That's a great finish with the rustoleum. Quite impressive.
> 
> That Bamboo ply is more reasonable than I thought. How much was it per sheet after shipping if you don't mind me asking.


I believe I paid $85 freight for the 2 sheets shipped to my location. Did you notice the 2 sheet minimum order?

When compared to even very high quality plywood, the bamboo is pretty pricey, BUT the performance in terms of dimensional stability is superior. When making a baffle type speaker, you need it to be ultra stiff since there are no side, box walls for support. Also, the finish of the bamboo requires no veneering, so some savings are gained there as well.

Greg


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## GranteedEV

studiotech said:


> I believe I paid $85 freight for the 2 sheets shipped to my location. Did you notice the 2 sheet minimum order?
> 
> When compared to even very high quality plywood, the bamboo is pretty pricey, BUT the performance in terms of dimensional stability is superior. When making a baffle type speaker, you need it to be ultra stiff since there are no side, box walls for support. Also, the finish of the bamboo requires no veneering, so some savings are gained there as well.
> 
> Greg


You've got me interested.

Once I save up the money, I want to make a Nao Note. or maybe a DEQX based build mimicing the Nao Note's polar response :yikes: - and now I think I will use Bamboo too.

.......................someday. :devil: :innocent:


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## StereoClarity

I've long been a fan of the bamboo ply for those exact reasons. Plus, it looks cool as hell.

Two sheets order minimum isn't really a problem. I don't really know what I could make out of just one sheet lol


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## studiotech

I still need to get some measurements up here, but in the mean time, here is the new equipment stand I'm workin' on. Shelves to be leftover bamboo plywood to match the baffles.

Greg


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## Navydoc

I am a fan of 8020, I am making speaker stands from the 3" material. Should be able to hold the largest of speakers with ease. Your stand with bamboo shelving will be really nice.


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## mjcmt

You have done a wonderful job with the wood working. I love the look of bamboo and I'll bet it's rigidity will stiffen the baffle for improved sound. Very cool indead. The next set of speakers I will build will be open baffle speakers, hopefully with a horn HF and 15" woofer, but I have a lot of research to do first.


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## Zeitgeist

studiotech said:


> I still need to get some measurements up here, but in the mean time, here is the new equipment stand I'm workin' on. Shelves to be leftover bamboo plywood to match the baffles.
> 
> Greg


Is that all Bosch-Rexroth Aluminum Framing system components? Not cheap but very strong and cool!


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## studiotech

mjcmt said:


> You have done a wonderful job with the wood working. I love the look of bamboo and I'll bet it's rigidity will stiffen the baffle for improved sound. Very cool indead. The next set of speakers I will build will be open baffle speakers, hopefully with a horn HF and 15" woofer, but I have a lot of research to do first.


Thanks! I made test baffles out of plywood/mdf/plywood and they felt bendable and made a dull clunk when hit with something. These bamboo baffles feel so stiff in comparison and make a much higher pitched sound when given the trusty knuckle test.


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## studiotech

Zeitgeist said:


> Is that all Bosch-Rexroth Aluminum Framing system components? Not cheap but very strong and cool!


Most certainly NOT the Bosch stuff. Too expensive. I got mine from Faztek.com Still not exactly cheap, but worth every penny.

Greg


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## studiotech

Navydoc said:


> I am a fan of 8020, I am making speaker stands from the 3" material. Should be able to hold the largest of speakers with ease. Your stand with bamboo shelving will be really nice.


The vertical legs are 3" material. The lighter gauge though, so they sound pretty hollow. I will probably fill them with something before final assembly. You might want to do the same with the speaker stands.


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## mjcmt

Navydoc said:


> I am a fan of 8020, I am making speaker stands from the 3" material. Should be able to hold the largest of speakers with ease. Your stand with bamboo shelving will be really nice.


I've looked at the 80/20 Inc. site and it looks like nice product. I've yet to get a quote from them. Have you made your stands yet? If so are you able to post a photo. I'd like to see what you've done.


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## Navydoc

mjcmt said:


> I've looked at the 80/20 Inc. site and it looks like nice product. I've yet to get a quote from them. Have you made your stands yet? If so are you able to post a photo. I'd like to see what you've done.


Okay, no laughing at the photo! I moved to Cambodia during the middle of building the 4 Pi speakers shown in the photo. I had the sub boxes built once I arrived for $25/ea. So for now, the 80/20 material is *not *being used as I envisioned.

However, I brought a tap with me so I can thread both ends of the material. I will be ordering bolts and washers from Amazon in a few weeks(but it takes 2 - 4 weeks for delivery). The plan is to attach plywood to the 8" lengths of 15 Series 3" x 3" T-Slot Aluminum Extrusion (Part #3030) as shown in the second attachment. I bought the material from the 80/20 Ebay store (http://stores.ebay.com/8020-Inc-Gar...=6479546&_sid=129537225&_trksid=p4634.c0.m322).

I plan on filling the inner core with material such as sand or lead shot (if available). No timeline on when I can get this done, the speakers sound pretty awesome as is. I have added 1" thick rubber feet in between the 80/20 material and the speaker since the photo was taken.


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## studiotech

Those are gonna be nice! Suitably chunky for those cabinets. Faztek makes a nice silicon rubber insert for the slot that would be perfect under the wood. I just ordered some for under the shelves on mine. I'm sure 80/20 has it too.


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## studiotech

Equipment stand in place and cradles for the subs created.


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