My first project is a 4 way speaker...

[cochinada]

I just did a measurement and the threaded rod is just over 20 mm and looking at the online specs you can adjust that by another 5 mm. I have no problem taking them on and off by hand, but I do tip the cabinet to one side to do that rather than trying it with the cabinet flat, that way your not trying to move the entire cabinet.

Here is the link to the place I got them from http://www.avoutlet.com/index.php?di...roduct_id=1577, looks like they still have them for half of what I have seen them else where ... not sure if it would be worth it getting them sent to Europe or not, might be worth crunching the numbers at that price. They also carry Viablue cable stuff as well.

Besides the looks one of the main reasons I picked them, was their ability to support almost 450 lbs, everything else I looked at was around a 100 lbs for a set.

Thanks for all the trouble!

When you say 20 mm do you mean 10 mm to the outside and 10 mm inside like this?

Image not available

If so, then for a steel plate of 10mm I came up with something like this (only the bar at the front is shown):

Image not available

and a transparent view...

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I'm trying to imagine what happens when we increase the first height adjustment to the maximum 5 mm. So I wonder, which scenario is correct?

1)

Image not available

2)

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3)

Image not available

4)

Image not available

...or none of the above?

[cochinada]

That price isn't bad at all!

Yes, the price is very close to this in Europe which until now was the lowest I saw.

[Steve Manning]

Thanks for all the trouble!

When you say 20 mm do you mean 10 mm to the outside and 10 mm inside like this?

Image not available

If so, then for a steel plate of 10mm I came up with something like this (only the bar at the front is shown):

Image not available

and a transparent view...

Image not available

I'm trying to imagine what happens when we increase the first height adjustment to the maximum 5 mm. So I wonder, which scenario is correct?

1)

Image not available

2)

Image not available

3)

Image not available

4)

Image not available

...or none of the above?

It's 10 in and 10 out, there is a small section in the middle that has no threads on the stud. The 5 mm adjustment is from the two main pieces ..... looks like Groups from what you have drawn.

[Steve Manning]

That price isn't bad at all!

That's what I thought when I found it ...... I found them a few other places here in the states but they were ~$130 a set ..... made it a no brainer.

[cochinada]

It's 10 in and 10 out, there is a small section in the middle that has no threads on the stud. The 5 mm adjustment is from the two main pieces ..... looks like #4 from what you have drawn.

Strange contraption... So, basically you just twist the disc in the middle and somehow the thread rod never moves. Is this what you're saying?

[Steve Manning]

Strange contraption... So, basically you just twist the disc in the middle and somehow the thread rod never moves. Is this what you're saying?

That's about it

[cochinada]

That's about it

Ok and what about the size of those so called 'grounding components'? They seem to be on the smallish size. Is this a nuisance?

[Steve Manning]

Monitor Audio does a similar construction with threaded rods through the back of their PL line. I think the Monitor Audio design would be easier to duplicate.

Image not available

I did a little looking and you could go this route with the following parts .........

Use something like this in the back of the baffles .......

http://www.mcmaster.com/#standard-threaded-inserts/=wjdxs5

http://www.mcmaster.com/#90016a030/=wjdykk

To connect the baffle to the back of the cabinet these could work ....

http://www.mcmaster.com/#threaded-precision-shafts/=wjdzk9

http://www.mcmaster.com/#8350t72/=wje2ci

Use these for the back of the cabinet in some recessed holes ....

http://www.mcmaster.com/#92908a155/=wje0gr

And to finish the connection cut one of these to length .......

http://www.mcmaster.com/#90585a554/=wje5tz

[cochinada]

Thanks Steve! That's very interesting. So, the idea if I'm getting this right and as far as the assembly goes, would be to attach the Hardened Shafts to the Tapping Inserts already mounted on the back of the baffle and then to place it carefully making sure the shafts are aligned with the screw holes at the back where we would finally tighten this whole set. With so many pieces turning I wonder if the shafts won't become lose in the process.

[cochinada]

Actually I really like this approach, allowing you to do removable baffles that can be decoupled by a layer of something squishy between the baffle and the cabinet hmm..

* Do not glue the baffle in place, same reason as the dowels, float it with a gasket. Magico did that with their original Mini.
Steve

But what's the great advantage of this solution? After all the baffle would be connected to the back of the speaker instead of glued to the whole and if the ply expands or contracts won't this cause the same problems? Am I missing something here?:roll:

OK I went back and here is the answer:

Hi Cochinada,

As to the baffle question ....... I glued and doweled the baffle and back into place, which I think is where most of my trouble came from. You can see the holes in the pictures I posted. I found out from looking at some construction pictures of older Magico speakers, that they have an o-ring in the back of the baffle and back insert for sealing and then bolt the baffle and back together though the cabinet. This lets the cabinet float independent to the baffle, allowing the wood to move around as needed.

Steve

Let the cabinet float doesn't sound too good. I mean if it moves that much, at some point we could have noticeable gaps between the side walls and the baffle for instance.

Makes it nice if you want to mount your drivers on the backside of the baffle as well.

That's one point in favour fur sure.

[Steve Manning]

Thanks Steve! That's very interesting. So, the idea if I'm getting this right and as far as the assembly goes, would be to attach the Hardened Shafts to the Tapping Inserts already mounted on the back of the baffle and then to place it carefully making sure the shafts are aligned with the screw holes at the back where we would finally tighten this whole set. With so many pieces turning I wonder if the shafts won't become lose in the process.

Loctite will fix that problem, I think these guys use a bunch of it http://magico.net/Technology/Enclosu...losures_05.php, as well as these guys, http://www.yg-acoustics.com/. Some of their cabinets have over 1500 parts in them!

[Steve Manning]

Let the cabinet float doesn't sound too good. I mean if it moves that much, at some point we could have noticeable gaps between the side walls and the baffle for instance.

Wood moves, period, some species more than others. You can do things to help reduce that movement and some things to work with it, when it does happen, this is one of the later. You will not be seeing huge gaps when it happens but your trying to stop these kinds of gaps from occurring ....



One of my cabinets when it split when I did not know about the above ideas!

Again Magico used this method when they made the Mini I & II and still use it in their all metal cabinets. Could be there on to something?

[TEK]

Let the cabinet float doesn't sound too good. I mean if it moves that much, at some point we could have noticeable gaps between the side walls and the baffle for instance.

I guess that is why you typically have some kind of design separation between the baffel and the rest of the cabinet, as a line, different colors and so on - so that those kind of movements does not show.

[cochinada]

Wood moves, period, some species more than others. You can do things to help reduce that movement and some things to work with it, when it does happen, this is one of the later. You will not be seeing huge gaps when it happens but your trying to stop these kinds of gaps from occurring ....

[ATTACH=CONFIG]23968[/ATTACH]

One of my cabinets when it split when I did not know about the above ideas!

Again Magico used this method when they made the Mini I & II and still use it in their all metal cabinets. Could be there on to something?

That is one serious gap! 8O
Now I can understand that Magico and others use this method for wooden cabinets but for metal too? How come if metal doesn't move (unless of course someone heats it but I'm not seeing anyone heating their speakers on purpose)? So, what might be the reason in this case?

I guess that is why you typically have some kind of design separation between the baffel and the rest of the cabinet, as a line, different colors and so on - so that those kind of movements does not show.

Could be... never thought about that before...

Since we are discussing construction techniques and materials and some posts back somebody mentioned bamboo (I believe it was you Steve) I wonder what to use. For aesthetic reasons the outer walls must be of BB ply. But I didn't decide yet if the braces will be made of MDF or again BB and if for instance to use or not some kind of sandwich or double layer since the walls will be 30mm (1.18"). I've been reading other threads as I'm sure this is a recurrent topic endlessly debated but still I would appreciate your thoughts about it. Is there any advantage in using more than one material in layers or this simply does not apply for MDF and BB? I've also read hear somewhere that bamboo is very expensive (with an E) and this has to be considered as well.

[TEK]

MDF or BB is normally used for inner bracing. It seems to me that MDF was used all around in the earlier days, but that this has shifted towards using more BB ply.
If you look at the ardent build the walls are 12mm MDF and 18mm BB. Inner bracings are 18mm BB as well (there are some bamboo in the baffel as well).
Jon build one out of pure bamboo a while ago - that was a nice one!

I would have used BB for inner bracing. It's quite much stiffer than MDF.
Bamboo is even stiffer, but expensive and might be hard to source, so using it for inner bracing seems like a overkill.
Of course, at least in Norway, BB is 2-3 times the cost of MDF, so if you want to save money you should probably go for MDF.

[cochinada]

I've looked at some Arden threads but there is more than one so I don't know exactly which one are you referring. Is it the Official-Wavecor-Ardent-Reference-Thread-How-we-realized-the-Dream or another one?

Anyway and moving on, I spoke with my carpenter and he doesn't have much experience with Bamboo and can only think about one supplier which inevitably means that the price of the material will be even more aggravated so this is almost excluded which leaves us with good old MDF and BB. Now he also mentioned that by definition (and he has a point) a sandwich is a composition of an odd number of different materials or layers where the inner and the outer are the same but the middle ones can vary in direction, thickness or material. By this definition these are some example valid sandwiches with a total of 30mm thickness:

BB9 + MDF12 + BB9
BB12 + MDF6 + BB12
BB12 + MDF9 + BB9 (not really a sandwich as above)

He can only secure BB in 9, 12, 15, 18, 21, 24, 27 and 30mm so the combinations are not that many and in fact these are the only ones I believe make any sense as using anything thinner than 6mm or not using at all won't make much difference I guess. Notwithstanding I would always have to use BB9 and BB12 whatever option I chose inasmuch the top of the speaker has to be entirely of BB and 12 + 9 + 9 = 30mm which is the right thickness.

Alternatively and this goes along with some builds here like the mentioned Arden, I can drop the sandwich concept and use a double layer only. What difference does this make I don't know...

One thing is settled though: the bracing will be in BB12 instead of MDF. I don't want it to be thicker as it would rob too much volume not to mention adding weight and also there is no need because the structure will be stiffer enough.

[TEK]

You had the right ardent thread ;-)

When it comes to materials you do of course also have a lot of other options, like sand filled walls, sandwich constructions with alu as the center layer and so on...
There are endless discussions out there regarding this matter.

With 300mm thick wall I belive that MDF and BB will be a more than good enough construction.
When it comes to sandwich or just two layers I think that 3 layers is more work than two - so if you go for BB - MDF - BB it should be because you think you gain something.

Just curious, you have several times mentioned that the final layer must be BB. Why is that?

[cochinada]

You had the right ardent thread ;-)

When it comes to materials you do of course also have a lot of other options, like sand filled walls, sandwich constructions with alu as the center layer and so on...
There are endless discussions out there regarding this matter.

As much as I find exotic to build speakers with aluminium on the walls and I do, the cost with be just prohibitive and besides I don't know anyone that I thrust enough that would be able to cut it using CNC. With my carpenter I have a different relationship but I don't believe he's willing to step out of his comfort zone as he has more than enough 'normal' customers already that don't ask him to do strange things.

With 300mm thick wall I belive that MDF and BB will be a more than good enough construction.
When it comes to sandwich or just two layers I think that 3 layers is more work than two - so if you go for BB - MDF - BB it should be because you think you gain something.

Just curious, you have several times mentioned that the final layer must be BB. Why is that?

Well, that is also my question : The truth is I don't have a clue weather or not is anything to gain from a sandwich vs. a two layer building. Perhaps someone here has a substantiated opinion?

The final layer has to be BB (or Bamboo) because I don't want to use any paint and veneering is also out of the question due to the shape of the speaker, namely the top, bottom and corners. This was discussed some point earlier if you want to know more details.

Open options so far:

Sandwich (3 layers - BB + MDF + BB)

a) 12 + 6 + 12
b) 9 + 12 + 9
c) 12 + 9 + 9 <--- cheaper *

Double layer (outer BB + inner MDF)

d) 15 + 15

Simple Layer (BB) **

e) 30
f) 12 + 9 + 9


* for the sandwich and because I'll always need BB12 and BB9 with the exception bellow (see post #107) it requires less different thicknesses.
** the bracing will be BB12 so I'll either use BB30 and BB12 or BB12 and BB9 alone in which case I need to glue three boards together to make 30mm.

[cochinada]

I keep reading over and over again not only here but in many other forums that BB is much lighter than MDF. Now I don't know where this idea came from because all it takes is a little research and we will get that the average density of BB is about the same as of MDF. Just google it. So, unless someone spread a wrong piece of information and everything started from that the only explanation is that in the US you guys are using a different sort of BB and/or MDF as from the rest of the world.

http://www.gardenguides.com/132288-baltic-birch-density.html

http://www.answers.com/Q/What_is_the_density_of_Baltic_birch_plywood

"...Birch has a density of 670 kg/m3, Aspen 420 kg/m3, and Fir 530 kg/m3..."

http://forum.speakerplans.com/baltic-birch_topic51363.html

"...Btw, baltic birch plywood and MDF density are pretty much identical at typical 620-670 kg/m2 for the MDF and 680-700 kg/m2 for baltic birch plywood. ..." (he means m3 and not m2 of course)

My conclusion: when we talk about weight, I'm afraid that Birch it's pretty much the same as MDF and not lighter.

[TEK]

Not sure where that was mentioned in this thread, but are you sure that it is not in the context of being able to use less material with BB than MDF to get the same stiffness - thus causing the end result to be lighter?

[cochinada]

Not sure where that was mentioned in this thread, but are you sure that it is not in the context of being able to use less material with BB than MDF to get the same stiffness - thus causing the end result to be lighter?

Not on this thread. I didn't explain myself right. 'Here' as in this forum and many others. Of all the threads I've read so far, in almost all the general opinion seems to be that BB is lighter than MDF where this is simply not true. Perhaps like you say people build boxes thinner with BB but the general idea among most participants is really that MDF is heavier or denser than BB.

At this point I'm inclined to one of two options for the outer walls: BB30 or a sandwich of BB12 + MDF9 + BB9.

There are pros and cons that I'm evaluating and still have to read much more. The first option in terms of materials is cheaper but just by a small margin (about 5%). However, considering the extra work I imagine the difference goes higher. In favour of the sandwich method we have 'only' the probable better quality of the boxes. I'm not in the least concerned about issues like dust which the general consensus says is the worse for MDF What matters to me is only to answer this question: is it worthy to make a sandwich over a simple BB construction or are the gains mostly negligible specially with BB30 walls and BB12 internal bracing? And if so, how much is worth it?

[---k---]

We have a children's game here in the states called "telephone". You might have it also. The idea is to take a class of children. Line them up. Whisper a secret in the first child's ear and have them rely it down the line. The climax is when the last child reveals the secret and compares to the first child. I think internet forums are pretty much this game in a nut shell.

Based on my experience handling them both, the birch ply is slightly lighter. I can tell when picking it up and stuff, but it isn't a huge difference. The numbers you show above would support my guess of 5% - 10%. So something. Best case, does a 100# speaker versus a 90# speaker make much difference? Not really.

I know I've seen the pro guys, especially the guys building the Tuba folded horn subs champion using 1/2" plywood. Specifically, they specify Arauco plywood. From their pdf http://www.arauco.cl/pdf/Araucoply_dic_05.pdf "Weight is messured considering a density of 540 kg/m3 at 8% moisture content" So, that is getting quite a bit lighter compared to what you listed above. They like well braced 1/2" ply. I don't think you could get the same durability from 1/2" mdf.

I wouldn't trust answers.com and gardenweb.com . But it is start.

So, some truth, but not across the board.


I think doing some exotic sandwich could make very small theoretical improvements. But, I think it introduces other complications and construction things that need thought about and probably some experimentation to really make it worth it. Since this is your first speakers, a one and done thing, and since you're having someone else build it for you; I would suggest going with all ply or all MDF. If this was your third or fourth speaker and you've experimented to see what makes a difference and how to glue things up and how to deal with differences in expansion and contraction and all, the suggestion might be different.

[cochinada]

We have a children's game here in the states called "telephone". You might have it also. The idea is to take a class of children. Line them up. Whisper a secret in the first child's ear and have them rely it down the line. The climax is when the last child reveals the secret and compares to the first child. I think internet forums are pretty much this game in a nut shell.

Based on my experience handling them both, the birch ply is slightly lighter. I can tell when picking it up and stuff, but it isn't a huge difference. The numbers you show above would support my guess of 5% - 10%. So something. Best case, does a 100# speaker versus a 90# speaker make much difference? Not really.

I know I've seen the pro guys, especially the guys building the Tuba folded horn subs champion using 1/2" plywood. Specifically, they specify Arauco plywood. From their pdf http://www.arauco.cl/pdf/Araucoply_dic_05.pdf "Weight is messured considering a density of 540 kg/m3 at 8% moisture content" So, that is getting quite a bit lighter compared to what you listed above. They like well braced 1/2" ply. I don't think you could get the same durability from 1/2" mdf.

I wouldn't trust answers.com and gardenweb.com . But it is start.

So, some truth, but not across the board.


I think doing some exotic sandwich could make very small theoretical improvements. But, I think it introduces other complications and construction things that need thought about and probably some experimentation to really make it worth it. Since this is your first speakers, a one and done thing, and since you're having someone else build it for you; I would suggest going with all ply or all MDF. If this was your third or fourth speaker and you've experimented to see what makes a difference and how to glue things up and how to deal with differences in expansion and contraction and all, the suggestion might be different.

I liked that analogy with the telephone game. I agree and go even further that this can apply not only to internet forums.

This is a technical info taken from a catalogue of a supplier of plywood where I live. If we do the maths we came to the value of 680kg/m3 for BB:

Image not available

Anyway there seems to be more than one kind of plywood commonly or maybe erroneously known by Baltic Birch so perhaps that's the case. This 'Arauco' looks significantly lighter and we are at the same page about the 1/2" brace ply which I'm going to use.

Those quotes were the first ones significant that popped up on a quick search but you are right about being cautious. Heck I don't even trust the most famous repository of information nowadays for that matter. Nevertheless I couldn't find another site mentioning that 'normal' BB was lighter than MDF.

You offer some wise advice I grant you that . The problem with the sandwich that is kinda scaring me a bit is the increased amount of work and difficulty in the gluing process. After reading almost a dozen threads, some in forums I never even heard before and others so huge that if we extract the valid information this would not amount more than 1% I dare say, I liked this quote in particular by an another forum's member called Svante:

"First, fibreglass damping inside the box has very little direct effect on structural resonances in the box. The main purpuse of box stuffing is to attenuate the acoustical resonances in the air cavity. On the other hand the fibreglass may actually reduce the vibration of the walls indirectly, since damping the air cavity resonances reduces the sound pressure at these; this in turn leads to less vibration in the walls, at the cavity resonaces.

Second, people that I know that know structural dynamics tell me that the best way to apply damping to a mechanical structure is to make a sandwich construction. If the damping layer is in the middle of the wall (eg damping glue between two sheets of MDF) there will be strong shear forces on the damping glue, and so it will absorb a lot of energy.

Applying damping material (asphalt, carpets etc) on the inside of the box is of course not bad, but it is far less effective than a sandwich construction.

Third, bracing shifts the resonances upwards and makes them more resonant (higher Q). At these higher frequencies, the exciting forces are typically smaller, and this reduces the problem with panel vibration, in spite of the higher Q values."

[cochinada]

Another thought is crossing my mind...

What if, instead of using BB30 for the outer walls I used only 24mm but with two identical layers of BB12 glued together? I'm thinking that perhaps 30mm is overkill as BB is stiffer than MDF and this way I would have the benefits of a double layer together with savings in different materials as the bracing would also be in BB12.

However... if any ply is actually made of several sheets glued together already I have trouble finding any advantage in gluing two sheets of BB opposed to just one with double thickness. :roll:
Now if we were talking about different materials...

[BobEllis]

... if any ply is actually made of several sheets glued together already I have trouble finding any advantage in gluing two sheets of BB opposed to just one with double thickness. :roll:
Now if we were talking about different materials...

Agreed. I'd be surprised if the cost of 2 12 mm thicknesses would be significantly different than a single equivalent thickness.

The downside is more work laminating panels up, so IMHO you're better off just using a single thicker panel.

[cochinada]

Agreed. I'd be surprised if the cost of 2 12 mm thicknesses would be significantly different than a single equivalent thickness.

The downside is more work laminating panels up, so IMHO you're better off just using a single thicker panel.

Actually 2 sheets of BB12 cost about 17% more than one single BB24 so I guess this isn't a good idea.

[cochinada]

I found an interesting table of properties put together for some of the most common materials used in speaker building. According to Wikipedia the values seem correct enough in order to validate some considerations and choices.

Image not available

This one for instance gives the equivalent thickness of materials for constant deflection:

Image not available

Some interesting conclusions are made here where I also took the above pictures from.

These charts here look also very informative and cover even more materials.


Bottom line is that Baltic Birch has indeed the same density of MDF or just a tiny bit less, contrary to the general notion amongst most people, however as it's specific stiffness is more than 3 times the one of MDF an equivalent box can be made with only 68% of the thickness and hence be much lighter as Ryan (-k-) very well guessed.

[---k---]

Bottom line is that Baltic Birch has indeed the same density of MDF or just a tiny bit less.

3.5% less. You know, I've seen people make threads 30 pages long arguing over something more straightforward than whether 3.5% is "the same or just a tiny bit less." You better be careful.

Have you registered at apawood.org? I'm guessing they'd have your best information if you want to continue the quest. I got some of their printed guides on my shelf, but nothing plywood or mdf related. I'm to lazy to register for another website.

[cochinada]

3.5% less. You know, I've seen people make threads 30 pages long arguing over something more straightforward than whether 3.5% is "the same or just a tiny bit less." You better be careful.

Have you registered at apawood.org? I'm guessing they'd have your best information if you want to continue the quest. I got some of their printed guides on my shelf, but nothing plywood or mdf related. I'm to lazy to register for another website.

I'll leave those endless discussions for some else. For me the matter is settled and I'm also overwhelmed already with enough memberships and forums so I think I will pass but thanks for the tip! I will follow my KISS philosophy instead of pursuing castles in the air as I'm no Don Quixote Therefore I will use BB all the way without sandwiches of any kind.

I will just optimize the bracing and so I've been busy redrawing it and came up with this structure that I think will be the final.

Image not available

The modifications were that now the baffle is also supported by 6 contact points directly connected to the back panels and I've added two horizontal strips at the back and three oblique braces as well to reinforce the subwoofer enclosure and lateral panels. Finally I reduced the number of vertical panels from three to two because with three I would have to split the back panel in two equal distances and I didn't thought this was a very good idea.

I hope this will give enough stiffness to the enclosure and help spread the vibrations as homogeneously as possible. I will also use this budget material for internal damping.

I almost forgot! The distance between each vertical brace and the closer side panel is related to the distance between both braces by phi as I believe that mother nature knows best and this 'golden ratio' is everywhere to be seen so I wanted it also to be present in this project.

[TEK]

It's looking impressive I have to say.
But I also have to say that I'm very happy that I'm not going to build this one ;-)

[Steve Manning]

Nice looking cabinet ..... though I don't know about it falling into the KISS category, but it looks like it should be fun to build. Out of curiosity how are you cutting all of your pieces?

[cochinada]

Thanks guys. That's really not that complicated.

This is the layout for the CNC cutting. In total I will need 5 BB30 and 3 BB12 boards:

Image not available

Unfortunately there is some waste but it's unavoidable.

[5th element]

Hehe CNC certainly does make more elaborate cabinet designs a lot simpler.

[Steve Manning]

What no hand saws, where's the fun in that I bet if you you did everything on a table saw you might have a different view of what simple is though. Of course I'd love to go the CNC route myself one day

[cochinada]

That's the best part of the machines. It doesn't matter what form or shape it cuts.

This is the data for the 12" from SB Accoustics before break-in. I have the drivers for some time but have been to lazy to measure them until now:

Image not available

[cochinada]

What no hand saws, where's the fun in that I bet if you you did everything on a table saw you might have a different view of what simple is though. Of course I'd love to go the CNC route myself one day

I leave that to the professionals

[TEK]

For me, using CNC is kindof cheating.
However, for me the building process - including sawing out and making he actual cabinet - is a important part of the journey. Hopefully in the end the result will be something that is really nice looking and good to listen to, but that's more just a end result and not necessarily the main goal of the build.
If I'm to go the CNC router is's probably because I first built the CNC machine and needed to test it 8)

But that's just me. We all have different prioritizes, and I'm VERY understanding that not all have the same priority as I have

[cochinada]

For me it isn't a matter of choice or priority as I simply don't have any other option but to order the making of the cabinets. You probably have seen or heard already about those peculiar sleeping rooms laying on top of each other mainly in Japan where space is at a premium, which basically consists of a minuscule bed and... that's it! These are common in airports and such places and are ways to spend a night. This is to say that unfortunately not everyone has the proper space for carpentry work, not that I leave in those conditions, otherwise I would have to leave the speakers on the outside but... I think you get the general idea. That being said I would love to build the cabinets myself but just because I can't I'm not going to let this come in the way.

Speaking about the cabinets, my carpenter has just told me that Bamboo after all is just a little bit more expensive that Baltic Birch but I don't have any more information about the material he can get. The only think I believe is true is that on the average bamboo is stiffer than BB and above all much stronger which makes it a very interesting alternative. I need to find out more...

[Juhazi]

The bass cab is too "long", it obviusly has a cavity resonance in the passband. Please us a dividing plate placed horizontally between midbass drivers, it can be thin 9-12m because pressure and pulses are identical on both sides.
-
Otherwise thumbs up, a superclass diy project!

[cochinada]

Thanks for your inputs!

The bass cab is too "long", it obviusly has a cavity resonance in the passband. Please us a dividing plate placed horizontally between midbass drivers, it can be thin 9-12m because pressure and pulses are identical on both sides.
-
Otherwise thumbs up, a superclass diy project!

Do you mean too "long" or too "tall"? Or perhaps you are talking about the small compartments surrounding the underneath and top of the subwoofers? Do you mean something like this?

Image not available

I would have to figure out the best way to glue this extra piece to the corner of the inside enclosure and make some holes in it as well right?

By the way, how can you tell there is a cavity resonance in the passband?

[Juhazi]

Yes you got it right. I actually mean standing waves, which tend to show up as peak/dip in response and "ringing" in CSD graphics. Cavity resonance, standing waves, pipe resonance etc. are determined by distances between opposing walls (openings) in a cavity/box. The greatest distance makes the lowest frequency. This applies to any box, room etc. Jus use any room mode calculator and set appropriate dimensions!

My guess is that longest path in your sketch is 100cm, corresponds to 170Hz standing wave.

http://www.trikustik.at/knowledge/room-modes-calculator.html

http://www.sengpielaudio.com/StandingWaves.htm

http://www.acs.psu.edu/drussell/Demos/StandingWaves/StandingWaves.html

http://abacus.bates.edu/~jsmedley/phys104/cavity.htm

[cochinada]

Here are some measures:

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[cochinada]

Things are moving on, slowly but steadily. People say the devil is in the details but I prefer to say beauty is in the details. So, the Viablue spikes have arrived and together with the Cardas binding posts they give a nice touch to the whole set in my opinion.

Sorry about the quality of the pictures but they were taken with my cell phone.

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Talking about details, I decided to go for a brushed steel plaque for the binding posts. One thing is yet to decide: what shall I engrave on it to differentiate the terminals. On the picture it is my initial idea but I'm considering other options like 'BASS', 'LOW', etc. What do you suggest? This is of course for the active part of the speaker and the 12" woofers. Note that the Cardas binding posts already have a '+' and a '-' sign.

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Finally I did a small change on the supports. This has to do with cosmetics only. I added a small cylinder in order to cover the thread of the spikes. It want rotate as it is welded. The supports will be made of stainless steel and I will have them powder coated with the same color as the Viablue spikes which is a dark grey.

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[TEK]

"WOOFER"
You have done some update sine the start?
Could you post a new full render? Interestef in seeing if it's much different now...

[cochinada]

"WOOFER"
You have done some update sine the start?
Could you post a new full render? Interestef in seeing if it's much different now...

Hi,

Not many changes. Regarding the bass boxes, I just chamfered the holes and edges of the matrix in post #133. As for the MTM I smoothed the inside making it less 'edgy'. Here are some pictures:

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