Sub design

[TEK]

Hello everyone...

I have recently, after some thinking, some looking and quite some gentle persuasion of my wife, found a solution to get a _real_ sub into my living/hifi/movie room.

The solution is to create a "copy" of the ekornes double "pallet".
A couple of examples is shown in the pictures:

Image not available



My idea is to basically start with the bottom part and build a sub with the (almost) same dimensions. I will then build the tops. After this is done I will take the lot to a professional and get it covered with leather in the same type as my stressless chairs. It should all blend nicely together.
I think the control panels for the sub will be on top of the sub box, but under the top covers. The element(s) will have to be pointed downwards.

However, if I calculate approx. 4cm thick sides, bottoms and tops in the sub, this will give me a inner box volume (with no bracing) of approx 175 liters :T
I think that should be enough to give me a pretty decent subwoofer :lol:

The inner sides of the sub box itself will measure 30 x 52 x 112 (h,w,l), given 4,0 cm side walls.
The outer total measurements of the ekornes double "pallet" is 48 x 60 x 120.

However, my question to you folks is if anyone has some good ideas about how to best harvest this volume.
Should I use one or two drivers (or more?)
Should I use one single large chamber or several chambers?
How much internal bracing should be added?
Is it necessarily to have 4 cm thick sides? If I change the wall size to 2 cm the inner volume could increase to between 200 and 220 liters.

My priority for the subwoofer is:
1) sound quality
2) sound quality
3) sound quality
4) sound pressure
(It will be used when watching movies in a 5.1 setup as well as music in both stereo and surround)
5) price

As the sub will not be located in the corner, but right between all the speakers, I guess that will add the importance of sound pressure, as the room reinforcement will be smaller. The equalizer part of the power element will also be quite important as the sub's location is fixed.
(as if I have ever could place the sub wherever I wanted :roll: )

Any inputs would be really nice :T

[Paul H]

You can create a very nice sub with the kind of box volumes you're talking about. I think you should stick with the 1 1/2" sides for vibration reduction - you did say sound quality was at the top of the list, and a more robust well-braced box will definitely help.

What's your driver and amplifier budget? - you can get some good suggestions from the gang here if we know how much you're looking to spend.

Paul

[ThomasW]

Hi haven't heard from you in a longtime.....

What brands of drivers to you have access to?

Do you need to buy from local suppliers or is importing them a possibility?

My understanding is that shipping and customs/taxes might be a deal breaker.

Knowing that will make things much easier.

[TEK]

Hi, thanks for the replys.
Yes, I have been "away" some time. New job, new child and stuff so it have been a bit mutch to do.

Import is not a problem at all. The dollar is currently very low/the Norwegian krone very high, so pricing is good when importing stuff.

The following is available from local dealers:
(*indicates preferrable due to special availability)
Eton*
Audio Technology*
Perless
Seas
Audax
ScanSpeak
But again, I do not think import of other brand is a problem at all. Having something "else" than "the lot" could be fun as well ;-)

Price range... hmm, actually not sure.
I think I initially would like to set a price target around 10k NOK (that's approx 1600-1700 USD ink freight to norway) for both the driver(s) and amplifier.
However, if that is to little or to mutch it should be adjusted to the best price/quality ratio.

It is important to have both line input and LFE input.
Volume adjustment should be independent for both inputs. Line input must support a low crossover point (it will be used to feed below my B&W N803's in stereo mode)

[ThomasW]

Unfortunately none of the brands listed are offering cutting edge subwoofer drivers at this point, unless one likes the Peerless XLS models.

On this side of the Atlantic, high performance subwoofer development is literally on fire. There are new companies, new drivers, and new technologies popping up every few months.

Do you have a preference for the box alignment? Ported, sealed, whatever?

BTW how big is the room, and what kind of SPL are you looking for?

[TEK]

Unfortunately none of the brands listed are offering cutting edge subwoofer drivers at this point, unless one likes the Peerless XLS models.

On this side of the Atlantic, high performance subwoofer development is literally on fire.
There are new companies, new drivers, and new technologies popping up every few months.

Then it seems like a good choice to pick something from your side of the ocean :T

Do you have a preference for the box alignment? Ported, sealed, whatever?

No, not really. Have an impression/been told that sealed is better than ported, if you have the volume to do so. I think that "thight" bass is important. Doesn't it have a tendency to become muddy when using a ported design?

BTW how big is the room, and what kind of SPL are you looking for?

The room is approx 70m2 and is L shaped. The speakers is located in a smaller "part" of the room.

PS: I belive that the sub will outlive my current living room (it's likly that we will be moving in a couple of years)

About SPL;¨
I do not have a number to put on it.
It's for home usage. I'm not trying to take the house down, neither to get my neighboors to sell out and I'm not running a disco.

It will be using it when watching movies, so it has to "handle" enough SPL to not "fall trough".

Sorry, I'm not sure what to say about it. ops:

If I should compare to something, I would say that if it can match the SPL of
B&W ASW850 it would be home safe with a mile to go.

[JonMarsh]

So, perhaps what you're thinking about is a relatively small sealed box, with a long throw driver, and enough EQ and power to provide the deep bass, based on having a linear long throw motor to work with in the driver?

A new US company for sub drivers is Ascendent Audio; you have have seen the thread about new drivers in the Mission Possible group. Within their current spectrum, the large 15, the "Avalanche" 15 might be just what you need.

Image not available

This is the longer throw series from Chad's company; 27 mm Xmax, and using an XBL2 motor, technology licensed from Adire Audio. The price is quite attractive relative to the performance for competitive drivers. I have some of their 12" drivers on the way for a dipole system application.

Ascendant Audio

Then you'd need an amplifier, preferably with a Linkwitz transform EQ, though it can be done with more conventional equalizers, too.

But I'm not the sub "specialist" here; ThomasW and the others will give you lots of ideas.

Did you ever build any satelite speakers?

~Jon

[Andrew Pratt]

That driver should do all you could ever want a sub to do. It shouldn't need the whole volume either if it models anything like its Tumult cousin so you'd have no problems bracing it properly...trust me you won't believe how much pressure these drivers can produce. My Tumult box has 1.5" thick walls plus bracing and you can still feel resonances on the walls! As for the plate amp I'd locate it on the bottom not the top as its going to need room to cool properly. I'd also forget putting casters on the bottom as they'll need to be very industrial to support the weight so go with regular legs and add some teflon sliders if you want to be able to move it around a bit more easily (if even just to clean under it every now and then)

Have an impression/been told that sealed is better than ported, if you have the volume to do so. I think that "thight" bass is important. Doesn't it have a tendency to become muddy when using a ported design?

Sealed isn't any better then Ported...but its no worse either. Both designs have their pluses and minus depending on what you want but in general sealed tend to be smaller and tend to have a more gentle roll off where as ported can play louder down deep but are frequently larger and response drops off quickly at the tuning frequency. Of course there's always exceptions esp regarding box size but for the most part sound quality isn't an issue as either can sound very good when designed properly. If you have the amp power and an EQ you can easily make a sealed box play plenty loud enough and do deep enough for HT and music and with these ultra long throw drivers there's a very slim chance you'll bottom out the driver so there's no need to worry when you're showing off Lord of the Rings to your buddies

[Asterduc]

Tek,
- You want to go for sound quality, but you mention to use it for HT only.
- You are not a speaker designer, thus you want to copy a prooven design
- The room is 70 m², which is not exactly small
In that case I would defenitely choose for the Peerless XLS (http://www.d-s-t.com/main/tech/appxlsc2.htm). Normally I would suggest to choose for the 12" with passive radiator which sounds identical to a ported box, but without the distorsion and airflow noise. The huge volume you mention makes it also possible to build a sealed enclosure. You will loose some pressure, but on the other hand it will sound deeper and less stressed due to the smooter cut-off in the sub area. For quality do not save on a strong massive housing. I made a 10" XLS once and had to go to a matrix enclosure with 44 mm thick panels to keep the housing from resonating.

There are many enclosure idea's available for this Speaker units. If you can't find any, let me know and I will try to find any.
I am also willing to simulate the enclosure for you if you give me the right dimensions of the enclosure (total net volume).

Amp: my first choice in this system would be a Thommessen (http://www.thommessen.com/english/th..._frameset2.htm). Not cheap, but not expensive neither. You get a well balanced system that 'll be hard to beat from any existing Subwoofer.

Notice that the Thommessen / Peerless combination won't be realy spectacular, as it will give you a high quality sound without booming, without distorsion, without anything but clear and deep sound.

For more pressure, use 2 XLS units! you can mount them back to back to make a resonantfree housing. Well, that will be rather difficult while you are probably looking for a downfiring unit.

... and hey, speaker is made in Scandinavian, Amp's come from Germany. So they won't be difficult for you to get.

Any help, let me know.

[ThomasW]

When I ask about SPL I wasn't expecting a number, just an indication of your expectations. Do you want to accurately reproduce the depth charge explosions in U-571? Or is something more modest okay?

Exceeding the performance of the B&W sub won't be a problem. BTW, I hope you have access to a handtruck we don't design any 99lb weaking subs :wink:

As Andrew indicated and since you referenced a 15" driver the Adire Tumult is an exceptional driver. It's distortion figures are 2-3 times lower than similar drivers since it uses the XBL^2 technology. Also Adire's set up for shipping to Europe and they have a matching high power plate amp that can be set for different voltages.

The Adire ADA1200 plate amp has a built-in LT (linkwitz Transform) circuit. Those allow the sound of a low "Q" sealed design in an even smaller box.

Even though Adire has distributors in Europe some people are buying directly from Adire given the devalued US$. So I suggest shopping around.

If you want the tightest and detailed bass then yes a sealed design is needed. They have the lowest group delay and best transient response.

[TEK]

Jon/Andrew
I have read a bit on the Ascendent Audio drivers, but I haven't followed the thread in details. From what I found on their website, the 15" Avalanche only need 4 ft3 (gives a Q of .577), that's approx 12 liters if my calculation is correct :E
If it is correct, is this the correct driver to harwest the relative huge volume (175 liter) I have available in the best possible way?
PS: It looks VERY nice :T

I'll come back to the amplifier stuff when I'm feeling that I'm getting closer on selecting the correct elements and layout.


Asterduc:
"You want to go for sound quality, but you mention to use it for HT only. "
Sorry if I did not point this out clearly. It will absolutly be used for music as well. Both stereo and multichannel. The reson movie is mentioned is as that's where I think you normally find the most need for large SPL.

"You are not a speaker designer, thus you want to copy a prooven design"
Yes, or at least pretty proven. I do belive (correct me if I'm wrong) that loadspeaker calculation is very mutch easier than for example for a speaker. Especially as all frequency regulation on a sub is available "runtime" vs. "design time" for a loadspeaker.
This will of course vary dependent on the solution choosed. A servo driven solution may of course change this :W

"Amp: my first choice in this system would be a Thommessen "
I have looked at them before, and they are absolutly interesting. There is one thing about them that I'm wondering about. The lowest adjustable top frecvency seems to be 40Hz. This might be just a bit high when using them as bottom end of my main speakers during stereo playback.

Your solution with the Peerless sub's might be very good. A question is how they stand up against newer drivers developed "over there".
Also the Peerless does not seems to harweest the huge volume available (isn't around 50 liter pr element normal usage? I could suppert 3 or 4 of them)

Do the statment about music usage change your recommendations here?
Does anyone know mutch about the quality between the Peerless and other brands?

PS: I'm a bit pushy about the volume. It's of course no problem to make the sub smaller if that gives a good enough or better solution, but I really thought that having a huge volume available would really increase the quality with the correct usage and elements.

[TEK]

Thomas:
"Do you want to accurately reproduce the depth charge explosions in U-571? Or is something more modest okay"
I think something more modest is okay :

Accurat and correct bass is more important then getting sick due to to mutch bass!

Adire Tumult is also a well known driver that has been used a lot. I did a fast search but did not find any direct recommendations for closed box volume. What is the "optimal" for this driver? Maybe two would do the job :W

The "Adire ADA1200 plate amp" looked very interesting!

"If you want the tightest and detailed bass then yes a sealed design is needed"
This has been my understanding as well.

I guess I better go out and by myself a handtruck soon 8O ...

[GrahamT]

Hi Tek,
If you have the construction skills, then you should have no problem making an amazing sub with the help of the members here.

the 15" Avalanche only need 4 ft3 (gives a Q of .577), that's approx 12 liters if my calculation is correct

Not even close, 4 cubic feet is about 113L. You can use the unit calculator here:

http://www.linearteam.dk/default.aspx?pageid=unitconverter

The Avalanche 18 would work in that box. Chad recommends 4.6 to 7.5 cubic feet. You have about 6 cubic feet. Keep in mind you will lose enclosure volume due to the driver, amp and bracing.

Any XBL^2 driver in a suitable box should give you the accurate bass you are looking for with output to spare. It sounds like you want a mid to low Q design.

The Adire ADA1200 or 600 should work well for power. I dont know if there are better options over there.

[ThomasW]

He can't get anything from Ascendant at this time. So he needs to go with a Tumult unless he wants to wait an unknown amount of time. Because of it's reputation in Europe, a Tumult will have higher resale value, if necessary.

Since he has 175l to play with let's give him a fairly low "Q" design. He can always add boom with EQ to get the sound of a mid "Q" design.

He can use his approx 175L gross volume, do a double walled box made with 2 layers ~19mm Baltic ply and multiple internal braces to stiffen the box. That will get him in the low 0.5x "Q" range by the time everything is said and done.

If he uses the ADA1200 amp, he'll be able to get close enough to the U-571 explosions to scare the neighbors should the need arise ..... :wink:

[GrahamT]

He can't get anything from Ascendant at this time.

Yes, I forgot about that.

I wonder if the new drivers from CAC will be more affordable. Maybe they will be on display at CES.

[Spearmint]

TEK,

When you are ready to look at amps for your new sub, and if you decide on using a plate amp Hypex has a distributor in Norway. Could be worth getting some cost comparisons, and also check out the cost of some pro PA amps, you may be surprised at how affordable some of them are as well.

[TEK]

I did think that the numbers seems totally scruwed up, so the numbers from GrahamT makes mutch more sence.

Thomas: "He can't get anything from Ascendant at this time."
I guess that you are thinking about the none shipping abroad stuff?
That is not nessesarly a problem. There are suppliers that handles this issue. (They order stuff locally in the states from a lot of shops, and then ships many items in bulk to Norway).

[Asterduc]

Tek,
do the statment about music usage change your recommendations here?
it certainly does
If you want to produce good music with the Sub (I mostly disconnect my Sub when I listen to music, use it only for HT) the XLS wouldn't be my primairy choice anymore. The XLS has huge displacement and therefore isn't accurate and tight enough for best music production. I would rather go to a bigger speaker then. 15" units, 18" will be too big for the available volume. A unit with a relatively high Qts in sealed box will deliver good performance. You may look into semi-PA speakers as a cost efficient alternative on the new subunits although they won't go as low as those subunits. They have higher efficiency (cheaper Amp design can be used) and cost less, used with bassboost and driven only in their cut-off area might give good results. But this isn't a prooven design anymore.

[/I]The lowest adjustable top frecuency seems to be 40Hz[I]
that is correct, but isn't that low enough? Cut off is even more important than the actual frequency. You want the sub to do just 15 to 30 or so? hmmm. 40 Hz seems to be nice X-over for a large system to me. Don't fool yourself by thinking too low. The low E on a bass guitar is over 40 Hz, the Low B is 27 Hz, this is the lowest a 5-string can go. For your information, most bass guitars don't even produce their groundnote (27) but 2nd harmonic (54) instead.

Using multiple small units instead of 1 big unit will give you lower efficiency. I understand you want to go for extrem low. What you could do is: get a speaker simulation software on your PC, search the web for drivers and look for the best fitting curve in the simulation software.

[TEK]

About the crossover point.
When using the sub togheter with my mains, I do not want it to overlap the mains frequency area, but supplement them at the lower part. I want to let the main speakers do what they do best, and only let the sub supplement them on the area below.
My current front speakers is B&W N803. However the sub will problably outlive thease speakers.

My experience is that a good sub will add depth and richness to the music, even when used togheter with full range speakers. But it should not attemt to do the speakers job.

Your point on the XLS fits into my previous toughts.

How is the Tumult and the Avalanche 15" when it comes to this usage? According to Asterduc toughts on size, they should fit well.

"I understand you want to go for extrem low"
Yes, and no. I want to go for the best combination given the available volume. But sure, I'm absolutly interested in a sub that goes well below 30Hz. The sub is to add good quality low level output, not to add more SPL at higher freq (higher = 35-80hz)

I do think that a equalizer for the lower part might be a good idea, as those low frequencies is also the area where you might get into trouble with standing waves.

I also think that the fact that I will not be able to locate the sub wherever I want in the room (due to the fact that it will also work as a furniture) makes equalizer/room-correction support special important.

About drivers and the question about one vs two drivers.
It seems to me that most of you is recommending one single large driver (15" seems to be the one for my volume).
I also note that the REL state of the art subs for music (i.e. Studio III uses two 10" drivers).
However, they also uses ported designs.

The general understanding from you folks is that one single large driver is better than two smaller given the volume available here. Correct?

[Andrew Pratt]

Multiple smaller drivers tend to provide more volume then a single larger driver...at least that's normally the case. With these ultra long throw drivers like the ones we've been talking about that's not really true given the huge volume of air these can move. Larger drivers tend to be able to go deeper then smaller drivers as well (esp when you are talking about 10" vs 15")

As for the EQ yes IMO they're mandatory if you want to get the most from your subwoofer...there's no sense spending the kind of money we're talking about only to get poor results because you didn't spend the $100 more on a good EQ.

[GrahamT]

I agree with Andrew.

If I were you I would build the box Thomas described for the Tumult 15" and the Adire ADA1200 amp. Sound quality will be amazing, ask Andrew, and you will have plenty of extension.

If you can wait awhile, the Tumult 18 and other 15 and 18 inch XBL^2 drivers will be rolling out from Chile.

[Andrew Pratt]

Here's the response plot from my Tumult in a 75L box. As you can see it has no problems reaching down well below 30 Hz. The two curves you see are pre and post EQ.

Image not available

[JonMarsh]

About the crossover point.


The general understanding from you folks is that one single large driver is better than two smaller given the volume available here. Correct?

Put it in this perspective- you could have two long throw 12's with an XBL2 motor, or you could have one comparable motor/throw 15- the 15 would have an edge in swept volume, but cost overall would be significantly lower, because the voice coil/motor that's the biggest part of the driver expense.

Sometimes there are advantages to having two smaller subs, if the subs can't be placed ideally for the room, because you can distribute how you handle the room modes between the two, and get more even converge.

Regarding the Rels, which use two smaller drivers, these are excellent music subs- they have an extended upper range compared to many larger cone subs, and therefore are easier to integrate at the typical crossover frequency of 100 Hz, considering that a smooth and correct phase transistion requires good behavior for up to an octave past the crossover frequency. Many of the 15" woofers and even quite a few 12's are dropping in level above 80-100 Hz because of voice coil inductance. My own technique in setting up a sub is to EQ it for flattest overall response without the crossover from ~150 Hz down to 20 or so. Then, using the standard crossovers, things blend pretty well regardless of crossover frequency. The Adire Tumult holds up on it's own pretty well up to a few hundred Hz, with first major mode at about 600- quite high for a 15" sub driver.

Image not available

Which brings up one other point. The Nautilus 803 is designed for response down to the mid 20's. On paper, it doesn't need much help from a sub, especially if it was your intention to let it run full range, then just augment with what it doesn't cover. In practice, conventional full range speakers like this start to get a bit wobbly with regards to THD and IM as you go below 100 Hz and have the SPL's cranked up. They lack the swept area and volume of a true sub. The 803 uses dual 7" drivers for the bass- not a lot of swept area there, and no specs regarding driver Xmax.

If you set up a true crossover at a reasonable frequency (60 or 75) to XBL2 motor sub like the Adire, you'll find that you'd take a lot of workload off the lower end of your woofers, and the upper end will become much more at ease, with lower distortion and IM. I.E, your system will sound cleaner and have more dynamic impact.

Last comment: properly designed and EQ'd sealed subs have great transient response (can be critically damped), and low group delay. Tube Ported systems are a viable compromise, when you need to get some extended bottom end and dynamic range from smaller drivers- hence, you're B&W Nautilus being ported, most of my smalll box systems being ported, etc. Compromise comes into how the alignment works, and the resulting transient response (worse) and group delay (worse)

PR Systems are undoubtedly the champs of getting very high levels of LF SPL from very small boxes. They also have absolutely terrible transient response near the system tuning, and the worst group delay.

Thomas and I got into a bit of a debate a few years back about this point, back when the Stryke HE-15 was available and king of the sub drivers- the recommended design was a small cube with 1 15 and 3 PR's; we came up with an alternative design (the Aerial Stryke 15), which was ported. We were told we were crazy to build such a box, and to suggest it would outperform the Stryke cube, but you see, we'd actually built and tested both, something the other guys hadn't done. Only point, really, is that there is a lot of experience to draw on here at the HT Guide board, most gained from real world projects, not bench racing.

So, good luck with your project; I think if you go with the Tumult and the Adire amp, it will be hard for things to go wrong. Don't be afraid to experiment with the crossover setup, though; especially, I recommend trying and listening at some length to a 63 or 75 Hz crossover.

Best regards,

Jon

[ThomasW]

First I want those that don't already know, to see what I'm using for a reference when I talk about subwoofers. HERE's a link to a picture of my 'subwoofer'. It basically defines state of the art. Now before people start jumping up and down about there not being any 'big' drivers in it understand that when it was first built there weren't any good 15"s around. So I had to go with 12"s. The original driver were Shivas, the current drivers are DPL-12s

There aren't very many subs on the planet that can run with this big IB. So it is the reference for comparison when Jon or I design a 'normal' box sub. If a standard 'box' design isn't close to the sound quality of this unit, it hasn't been properly designed. And yes we are able to do A/B comparisons between the IB and other portable subs.

Now lets start separating fact from fiction.

1)big woofers are 'slow' and small woofers are 'fast'.

This is utter nonsense. And people that make these sweeping generalizations don't understand the fundamentals of loudspeaker design HERE's to a brief whitepaper discussing this issue. Now it's actually more complicated than this, but the info in the .pdf should be sufficient for purposes of this thread.

2) small driver subs are more musical.

Once again nonsense. If the drivers are high quality and the cabinet is properly designed, there will be absolutely no sound quality difference between small and large drivers

3)Subs that are good for HT aren't good for music, and subs good for music aren't good for HT.

Some idiot in a marketing department somewhere, should be shot for coming up with this. If a sub is good for music it will certainly be good for HT if it's been properly designed. Sometimes one can just up the output level or dial in a little EQ, to add emphasis to the DVD soundtracks

Lets cover crossover point choice.......

The XO point for the sub should be chosen so that the sub's output is still linear for one full octave above the XO point. For the mains, the XO point should be chosen so that their output is still linear for one full octave below the XO point. This guarantees there will be no holes in the response between the sub and the mains

When the above criteria is met, one can play around with varying XO points to get the best integration and best sound quality.

Now lets get on with more real world things......

Yes I'm aware of trans-shipping companies. If you add their fees onto the price of the Avalanche 15" you'll come up with something very close to buying direct from Adire. Also with a Tumult you're getting more Xmax.

So people don't think Jon and I are 'shilling' for Adire, take a look at our projects and you'll see drivers from lots and lots of companies. The drivers we recommend are based on what's best for the particular situation and nothing else. And yes we do recommend and use Peerless drivers when their products are appropriate for the application. In this instance they aren't in the same league as the drivers with XBL^2 technology

[GrahamT]

3)Subs that are good for HT aren't good for music, and subs good for music aren't good for HT.

Oh man do I hate that one. Especially when I hear people bash SVS subs. "Sure they have a flat frequency response, and sure they go loud with low distortion, but they aren't musical." Whenever I see the word musical I read it as "magical", just something that amuses me. :wink:

I dont think you guys will get accused of shilling for Adire. XBL^2 is just the overall best choice for low frequency transducers at this time for the DIYer IMO.

Thomas,

Those DPL12s look amazing, I wish I could build an IB. I bet it sounds out of this world, probably 0 distortion and tons of output.

[TEK]

Thomas:
You almost sounds a bit angry :M ?

About your "fact from fiction" statments
Your statments fits quite good with my own personal opinions. However, I do not have the knowledge/experience to back it up with.

About the Tumult vs Avalanche 15".
It seems that you mean that given approx the same price, there is no special benefit in using the Avalanche 15" compared to the Tumult.
Given the fuzz and that it was a very newly designed driver, I had the idea that it should/might outperform the Tumult. However, that might not be an easy thing to do :T

Based on the input it seems like the wote is going towards:
- A 175 liter box (I'll do some fine calculation regarding the actual volume after bracing and other stuff)
- Approx 4 cm thick sides + bracing (I have quite some material standing, so the actual used will depend a bit on that9
- One single Adire 15" Tumult
- The ADA1200 amp

Thomas:
with 2 layers ~19mm Baltic ply
What is Baltic ply ops: and why use it instead of MDF?

GrahamT:
If you can wait awhile, the Tumult 18 and other 15 and 18 inch XBL^2 drivers will be rolling out from Chile.
Tumult 18? Is this a new driver using the Tumult name?
I assume this indicates lower prices? Do you know anything about when this will happend and if it will be bought from Chile or from where?

[GrahamT]

Tek,

Baltic Birch plywood is very strong high quality void free plywood but it can be hard to find. You can find it at wood specialty shops, it can be expensive.

There will be a bunch of new drivers coming from the CAC plant in Chile, it is an affiliate of Adire. From what I understand, all the Adire drivers will be made there. The Tumult 18 will be shown at CES this week along with other new subs with XBL^2. I dont think the Tumults will be cheaper but you may see some other cheaper drivers with stacked top plates and stamped frames with XBL^2 but that is just speculation on my part. Adire says they plan to expand their sub range to 60 models.

[ThomasW]

Thomas:
You almost sounds a bit angry ?

Sorry it was a bad hair day and that tends to show through in my posts. Certainly nothing you posted. Maybe I'm going through "the change of life" :wink:

The word on the street is that the Ave driver is slightly more efficient than the Tumult. The Tumult has more Xmax. So it's a kind of a wash when comparing them.

As Graham indicated Baltic Birch ply is extremely strong and very stiff. It is the best wood material to build cabinets with. Tumults are HEAVY, and push a ton of air. You want a box that's up to the task.

BB ply doesn't 'machine' as nicely as MDF. So if you want to make the baffle board 3 layers thick (recommended) with the outer layer MDF that's fine. Just use BB ply for everything else (this includes the interior bracing).

Adire is increasing their product line by 500% when the CAC factory comes online. There are going to be dozens of new drivers. But I wouldn't plan on cheaper driver pricing for existing models given the falling value of the dollar.

The first units from the CAC factory aren't supposed to hit the US before sometime in Feb (that maybe a bit optimistic).

If you really want to go first class and $$$$pendy, the CAC factory has a second production line that will make custom designed drivers in lots as small as 2 units. Tell them what you want and they'll custom build a pair just for you .... :B

[Bent]

If you really want to go first class and $$$$pendy, the CAC factory has a second production line that will make custom designed drivers in lots as small as 2 units. Tell them what you want and they'll custom build a pair just for you ....

Parthenon Motor Madness???

[TEK]

Hmm, the Baltic Birch plywood was a small bump in the road.
Have a lot of MDF hanging around that I hoped to get used for the project.

I found some picture of it.



I think that I know what it is. I'll check the availability at my local wood dealer.
From the image I'm looking at, it seems as it has a nice finish. Is it sufficient to lacquer it, or does it needs veneer or painting?
(it's not sure if I will use leather around all of my version, or veneer/paint on the lower part and leather only on the top)

[Jack Gilvey]

The XLS has huge displacement and therefore isn't accurate and tight enough for best music production.

Are high Vd and accuracy mutually exclusive?

[Andrew Pratt]

No so long as the motor is strong enough to accelerate the cone fast enough...which obviously can be an issue no matter what the swept volume is.

[Dennis H]

TEK, that doesn't look like Baltic birch. Similar stuff goes by many names. In Norway, I'm sure "marine plywood" would be readily available. It's the same thing but with a waterproof glue for building boats. The characteristics to look for are all the plies inside are hardwood (doesn't have to be birch but it's common), the plies are thinner than normal so 3/4" (18-19mm) has 13 plies, and the plies are void free (no air spaces inside.)

That said, MDF should work fine if you build it strong enough. The finished sub will weigh more than one built out of plywood though.

[TEK]

Thanks for the input.
This is where I got the picture. It very clearly states what it is ...

http://www.woodnshop.com/hardwood/Baltic_Birch_Plywood.htm

I think that the waight issue is something that does need some consideration as I'm afraid this baby is going to be more than heavy enough...

[ThomasW]

BB ply is roughly the same weight as MDF.

You can paint it or stain it or veneer over it. The outside layer is furniture grade Birch.

TEK,

You didn't give enough info to reply to the question in your email

[TEK]

Thanks for the input so far folks. Very, very helpful!

I had to go back and do some more convincing of my "better part". After showing here the original box (shown in the first post) in the shop, she said;
Ohhh... it's bigger than it looked on the pictures!

However, after some gentle persuasion, everything is now back on track! :T

So now I have a couple of follow up questions:
1) Does anyone know/can recommend the distance I need between the bottom of the sub and the floor for a good result?

2) I have all this time assume that the Adire Tumult is suited as a downfirering element, but it would be nice to just get it confirmed.

3) Jon comment about the importancy of equalizing in his great post futher up. As I understand it, the ADA amps supports "Two full parametric EQ bands".
Does this mean that it will be possible to modify the bass response for two coherent rangens.
For example:
18-25hz, -2db
30-38hz, +3db
Will this be enough? I'm asking because this design initially will be activly targeting usage of eq to get the correct bass response.

[ThomasW]

You want the driver no less than 4" off the floor otherwise you'll create a resistive (aka slot) load.

Parametric EQ allows choice of the frequency, bandwidth, and amount of cut or boost.

It would be unusual for 2 bands of EQ to be enough, perhaps you'll be lucky ......

[Andrew Pratt]

So now I have a couple of follow up questions:
1) Does anyone know/can recommend the distance I need between the bottom of the sub and the floor for a good result?

I thought I'd read that Tom Vodhandles testing while designing the SVS subs found that 2-3" was plenty...granted that's a 12" driver vs the Tumults. I have 3" on mine and don't seem to see any adverse effect on the response.

2) I have all this time assume that the Adire Tumult is suited as a downfirering element, but it would be nice to just get it confirmed.

No problem down or side fireing.

3) Jon comment about the importancy of equalizing in his great post futher up. As I understand it, the ADA amps supports "Two full parametric EQ bands".
Does this mean that it will be possible to modify the bass response for two coherent rangens.
For example:
18-25hz, -2db
30-38hz, +3db
Will this be enough? I'm asking because this design initially will be activly targeting usage of eq to get the correct bass response.

Every time I've EQ's with my BFD I've ended up using between 6 and 9 bands to get it done right. 2 is a good start and taming some major problems but it won't come close to optomizing the whole response.

[Spearmint]

TEK,

One of the reasons for me suggesting looking at the Hypex amps, was not only do Adire distribute them but they are manufactured in the Netherlands, with a distributor in Norway. I figured it maybe a cheaper solution freight wise when coupled with say a Behringer FD1124p.

Maybe a HS1000

On the downside is you miss out on the inbuilt LT circuit, and of course the EQ.

[Bent]

Just to clarify...
The ADA series Adire plate amps don't have LT ccts built in, but they have the next best thing - a PC board c/w all the pads for the components for an LT.

[ThomasW]

I thought I'd read that Tom Vodhandles testing while designing the SVS subs found that 2-3" was plenty

TV's spacing is specifically designed to resistively load the driver. Doing so boosts the output at certain frequencies. This is not something the average DIYer should do unless they know what they're doing.

The 'recommeded' spacing to avoid any resistive loading, is to use a distance equal to the radius of the driver away from the floor.

[Bent]

or you could install the baseplate on "screw jacks" to allow tuning.

[Andrew Pratt]

The 'recommeded' spacing to avoid any resistive loading, is to use a distance equal to the radius of the driver away from the floor.

If that's the case virtually no sub I've seen meets that requirement?

[JonMarsh]

Well, Andrew, none of my subs are even floor loaded. Again, you can use this type of construction, but it DOES modify the frequency response, and should be "tuned" to the driver.

~Jon

[David R.]

The 'recommeded' spacing to avoid any resistive loading, is to use a distance equal to the radius of the driver away from the floor.

Would it not be the area of sub = to the total open area of the space (circumference x height)?

For example, SVS.. 12 sub area = 113sqinchs
circumference of a 16" circle = 48"s
113/48 = 2.35"s..

No?