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[Tomi Laukkanen]

Greetings everyone, I joined to this forum to search help from the pro to understanding and converting the measurements of the LAB Sub to use 2x15" subwoofers. My idea is to use 2x Focus Black SPL 15D2 elements on the LAB Sub design. My knowledge about the soul life of the subwoofer calculations and all that interaction between the driver and the housing that produces sound is very limited, but I do know that everything affects everything, so I can't just bolt 15" to it and hope it works the same way.

Now the more intresting details why I want to do it, well I'm DIY guy and like to build things and unfortunately my equipment and projects are allways overkills eventhough I don't intend it, but that's my nature and I like it. This folded horn would be used in hometheater, so I would replace my current on with that, I have 1 12" MDS woofer for my hometheater and it works good in my opinion, but there is a chance that there are standing waves in my room, but not sure. I feel that it rumbles nicely and sounds great, but then I feel it lacks certain punch, I really would like to see a movei where is earthquake and I wish that feeling would be transfered to this side of the picture. The size of the enclosure wouldn't be problem, because once it's put in place at the side of the room it would stay there and wouldn't be moved, although it would be good to have some ideas how to make it moveable so when cleaning or if it happens (most certainly after using that woofer) that I would move to a new house.

The specs for my MDS Audiophile TEAMR12 it has about 1750W constant and 3500W peak and the amp is T.AMP D3400 which is connected so that L and R channels are connected to their own coils. Yeah I know it's not normal hometheater subwoofer, but the was a trade show and I saw the MDS to be at discount so I couldn't resist and after I bought and started to search good subwoofer amplifier I was suprised to see that the biggest one was 800W rms, so it was out of question to use one.

I searched from the forums about this type of conversion, but there wasn't any reply that would give me the answer. I have heard from many that the folded horn/ snail shell is best type of construction in acoustics, someone have said why, but can't remember the reason.

Thank you everyone, even though I joined earlier I was too lazy to write this down and also Happy new year to everyone and better this year than previous one.

Tomi Laukkanen

[Ivan Beaver]

Greetings everyone, I joined to this forum to search help from the pro to understanding and converting the measurements of the LAB Sub to use 2x15" subwoofers. My idea is to use 2x Focus Black SPL 15D2 elements on the LAB Sub design. My knowledge about the soul life of the subwoofer calculations and all that interaction between the driver and the housing that produces sound is very limited, but I do know that everything affects everything, so I can't just bolt 15" to it and hope it works the same way.

Now the more intresting details why I want to do it, well I'm DIY guy and like to build things and unfortunately my equipment and projects are allways overkills eventhough I don't intend it, but that's my nature and I like it. This folded horn would be used in hometheater, so I would replace my current on with that, I have 1 12" MDS woofer for my hometheater and it works good in my opinion, but there is a chance that there are standing waves in my room, but not sure. I feel that it rumbles nicely and sounds great, but then I feel it lacks certain punch, I really would like to see a movei where is earthquake and I wish that feeling would be transfered to this side of the picture. The size of the enclosure wouldn't be problem, because once it's put in place at the side of the room it would stay there and wouldn't be moved, although it would be good to have some ideas how to make it moveable so when cleaning or if it happens (most certainly after using that woofer) that I would move to a new house.

The specs for my MDS Audiophile TEAMR12 it has about 1750W constant and 3500W peak and the amp is T.AMP D3400 which is connected so that L and R channels are connected to their own coils. Yeah I know it's not normal hometheater subwoofer, but the was a trade show and I saw the MDS to be at discount so I couldn't resist and after I bought and started to search good subwoofer amplifier I was suprised to see that the biggest one was 800W rms, so it was out of question to use one.

I searched from the forums about this type of conversion, but there wasn't any reply that would give me the answer. I have heard from many that the folded horn/ snail shell is best type of construction in acoustics, someone have said why, but can't remember the reason.

Thank you everyone, even though I joined earlier I was too lazy to write this down and also Happy new year to everyone and better this year than previous one.

Tomi Laukkanen

In a horn design, the loudspeaker driver the and cabinet are VERY intertwined.  You are correct it is not just a matter of making it fit (which if that was the only issue-would be quite a bit or redesign physically), but how do you know that the driver you choose is proper for a horn loaded design?

If you are asking for somebody to redesign the Lab sub for your drivers, they either have a lot of time on their hands-or you should be prepared to pay them for their work.

I would just stick with the proven design and not try to "reinvent the wheel" so to speak.

Another consideration is that it appear as it you want to use this cabinet for a home theatre situation.  Most home theatre people want their subs to go an octave below the lab sub.  That is NOT easy to do.  It will take a much larger horn-which brings in all sorts of new problems.

My suggestion is to just make either a ported box or an IB-each has its own advantages and disadvantages.

ANd remember that in low freq-the room size and how it is constructed are often a dominating factor.

[Tomi Laukkanen]

I'm not sure is it proper driver, but it the driver is ment for car competitions and it would create a good kick (in a proper box). I'm not asking someone else to design it just guidance about the calculations and the proper design. Of course another way would be to use Focus Black 12", but then again comes the fact it's not designed to used by that driver. I understand that many things has to be taken account when designing a good subwoofer box, but I'm not asking the design to be 100% perfect. I'm only curious about the possibility of adapting the design for the 15" and if it would be even reasonable. I do know that there are pros and cons in every box design, but I'm just trying to undestand what would be good design for my use. I do have heard about the horn design being great in audio and usually when I have roamed in forums where people are talking about subwoofers and their designs I have seen few times them to refer folded horn, because in their opinion it sounds and "feels" better, but I don't have any type of experience to say is it correct at all, don't have experience from many woofers.

This is why I asked from the pro so that I could get some guidance about the whole concept, I have seen a picture where someone made the folded horn type woofer, but it was built to be part of the house, a good way to dry your hair after the shower.

Thank you for the reply.

[Ivan Beaver]

I'm not sure is it proper driver, but it the driver is ment for car competitions and it would create a good kick (in a proper box). I'm not asking someone else to design it just guidance about the calculations and the proper design. Of course another way would be to use Focus Black 12", but then again comes the fact it's not designed to used by that driver. I understand that many things has to be taken account when designing a good subwoofer box, but I'm not asking the design to be 100% perfect. I'm only curious about the possibility of adapting the design for the 15" and if it would be even reasonable. I do know that there are pros and cons in every box design, but I'm just trying to undestand what would be good design for my use. I do have heard about the horn design being great in audio and usually when I have roamed in forums where people are talking about subwoofers and their designs I have seen few times them to refer folded horn, because in their opinion it sounds and "feels" better, but I don't have any type of experience to say is it correct at all, don't have experience from many woofers.

This is why I asked from the pro so that I could get some guidance about the whole concept, I have seen a picture where someone made the folded horn type woofer, but it was built to be part of the house, a good way to dry your hair after the shower.

Thank you for the reply.

Why are you "hung up" on that brand driver.  Why not use a driver that is known to work well in horn cabinets?  That would seem like the easier approach.

Guidance on a horn cabinet is something that is not easily given.  There are a LOT of variables that have to be considered.

Of course there are lots of 15" horn designs out there-so you could just build one and test it and see how well it works.

[Tomi Laukkanen]

I'm not so hung up for that driver it's more of what driver I have ment to use it, I have been searching for drivers to use, but ther variety isn't that big in here and I personally support local shops in here. Of course there are drivers, but that would mean to order 1 from abroad and even though it isn't hard but when thinking about that there comes transportation cost and top of that customs tax, it sometimes might come cheaper this way and also what I have been reading from the audio magazines the Focus Black won magazine award of the test series, so that also affected my opinion.

As you can imagine how hard it is for me, because I have searched a folded horn design to house 2x15" elements, some say 1 is enbough others say go with 2. I'm trying to get more understanding here, because every design and every guidance there is are more of peoples own opinions, so I'm just trying to sort out what is a correct opinion for my use. Someone might like good HiFi quality and some goes for brute bass.

The variables and that technical details are giving me bit hard time, but that's why I ask from people around here to give their opinion about it. I searched few websites about the folded horn and tapped horn designs and it's a huge variety of how one thing can be done. I noticed that sometimes speaking about folded horn it's not like the LAB Sub, the pathway of the sound isn't like snail shell, but more looks like an S letter from side. Is it because they use only 1 driver or is it, because it affects the pressure and reponse diffrently than the shell type configuration ?

I broke my ankle last thursday so I have plenty of time to spend on bed, so that's why I asked if someone could give me guidance of designing and calculatin one. I do have tried to search the best possible way, but I doubt I don't use the correct search words.

Thank you for your time

[Ivan Beaver]

I'm not so hung up for that driver it's more of what driver I have ment to use it, I have been searching for drivers to use, but ther variety isn't that big in here and I personally support local shops in here. Of course there are drivers, but that would mean to order 1 from abroad and even though it isn't hard but when thinking about that there comes transportation cost and top of that customs tax, it sometimes might come cheaper this way and also what I have been reading from the audio magazines the Focus Black won magazine award of the test series, so that also affected my opinion.

As you can imagine how hard it is for me, because I have searched a folded horn design to house 2x15" elements, some say 1 is enbough others say go with 2. I'm trying to get more understanding here, because every design and every guidance there is are more of peoples own opinions, so I'm just trying to sort out what is a correct opinion for my use. Someone might like good HiFi quality and some goes for brute bass.

The variables and that technical details are giving me bit hard time, but that's why I ask from people around here to give their opinion about it. I searched few websites about the folded horn and tapped horn designs and it's a huge variety of how one thing can be done. I noticed that sometimes speaking about folded horn it's not like the LAB Sub, the pathway of the sound isn't like snail shell, but more looks like an S letter from side. Is it because they use only 1 driver or is it, because it affects the pressure and reponse diffrently than the shell type configuration ?

I broke my ankle last thursday so I have plenty of time to spend on bed, so that's why I asked if someone could give me guidance of designing and calculatin one. I do have tried to search the best possible way, but I doubt I don't use the correct search words.

Thank you for your time

All loudspeakers are a tradeoff.  You trade one thing for another.  What is more important to one person is no so important to another.

Generally-with horns it is all about path length and mouth area.  The larger you can make each one results in lower and smoother response.

The shape is not as big a deal.  It is more about how much horn you can get into a particular size and waste as little area as possible.

There are various horn design programs out there.  I suggest you start with that and enter your driver parameters and see what you end up with.

There is also the DIY loudspeaker forum.

[Marjan Milosevic]

That driver has totally wrong T/S parameters to be used in a horn.
It has a Qts of 0.75. You need it to be in a 0.15-0.30 region.
BL is 9 and you need it to be close to 20.
Other things to consider.
Car loudspeakers manufacturers tend to over specify their products by a great margin. So i would take those 1750W with a quite a reserve.
Driver that is capable of use in a box like the lab sub has to have a very strong cone in order to survive the pressure built up in the chamber.
Remember, LAB sub is a PA cabinet, not a home cinema or car stereo box. Sure it can be used anyway you want but that is up to you.
As i can see that 12 inch driver is very expensive. It is actually more then double the price of a pair of LAB12 drivers that are the correct LAB sub driver. So that is not an excuse then.
Where are you based?

[Tim McCulloch]

Where are you based?

My guess is Party Central, i.e. Finnland.

[Tomi Laukkanen]

Party Central, that's intresting name, where that name comes from? XD, true I'm based in Finland where taxes are every possible part in price and there are taxes in taxes and gas price is high as hell, yay. About the strength well hard to say how good it is, it's reinforced with carbon fiber and double stitches runs around the sleeve. It is build for pressure use and the best record where this driver were used was 160.3dB

Like I said I'm just gathering info, and it is good to hear opinions about this and I have searched a program called WinISD Pro (which is alpha stage), haven't run it yet. Also the Qts in the Focus Black SPL 15" is 0.361, checked from their site. There is option to use 2x 1ohm or 2x 2ohm coils, the price doesn't change, also the parameter in the list is given at 1 Ohm, so you guys know better what it means and how does it affect in the use:
Fs 33,29Hz
Qms 3,353
QtS 0.361
Vas 53,3 L
SPL 88,9 dB
Qes 0.405
Mms 394
Re 0,95 Ohm
BL 13,99 TM

[Marjan Milosevic]

Look, as i get it you want to make a home theater sub. Right?
What do you think you will get with a single labsub?
Those boxes are rated to go down to 28Hz, but in a group of 6 boxes.
Single labsub will be more of a 38-40Hz box. Is that enough for you?
You can get that extension with a bandpass box of much less volume.

Another thing. 160db you say. How many of those drivers were used?
That can not be correct in any way.
At 88db sensitivity and powered with 1750W each, you will need about 700 of those ones to get to 160dbs at 1m distance.  At least what the calculation says.
Which again is not possible to measure at 1m.

[Marjan Milosevic]

Ah i just remembered. One of the finest Labsub builds are made in Norway.

http://www.cs.helsinki.fi/u/ljlukkar/labsub/

[Tomi Laukkanen]

Don't know how many were used, but that was the result in competition, also we have to remember we are speaking about car audio competition so the car itself acts as enclosure and the drivers are ment to withstand pressure and power, besides you are actally mixing 2 diffrent drivers, the MDS and the Focus, MDS is rated 1750W rms and the in the Acoustic website there were datasheet where it was stated to have an amplifier to provide minimum of 1200W RMS of power. If you read again my first post I told that my current subwoofer has MDS 12" driver in closed box, also I don't push the woofer to it's limits, because I have enough power in T.Amp to fry the coil if I want.

The idea is to have hometheater subwoofer, yes, but I have been roaming for 2 years searching a good design, but like I have said so many times in previous posts that there are so many crossing opinions what is good, one say it's closed box, another say you best use reflex port and another one the folded horn is a good way to go. There are opinions a lot of them and I have read from many sites that the horn type in acoustics is intresting concept which is good, but hard to calculate and build, that's why when I was roaming this site, many said it is better comparing other products (like Cerwin Vega) in sound.

So that's why I'm asking about the idea of using folded horn with dual 15" woofers.

[Marjan Milosevic]

That is all fine, but then again, even if you build a modified labsub and manage to fit those 15s inside, one box on its own will not give you more low end extension then a good reflex box.
This apply to any folded horn, they need to be in a multiple boxes to achieve their potential, or they have to be extremely big.

[g'bye, Dick Rees]

The combination of car audio and home-theater leads me to ask what kind of car you're living in.

[Ivan Beaver]

that's why when I was roaming this site, many said it is better comparing other products (like Cerwin Vega) in sound.

So that's why I'm asking about the idea of using folded horn with dual 15" woofers.

Cerwin Vegas are know for their "1 note bass", really loud over a limited freq response, but not low.

When was the last time you saw a measured response of one?

If you want low in a horn, you have to eitehr go really large-or use multiple boxes (as in really large).

When you put the wrong engine with the wrong transmission, you will not "get the best of both".

Again I will say-stick with proven designs and don't try to "make up your own".

Just because a particular driver make a loud noise in a small sealed cabinet (car volume), does not mean it will be good in  horn cabinet.

There is A REASON pro manufacturers don't use those types of woofers.  They are looking for different performance.

[Tomi Laukkanen]

Rees: I don't need yet to live in my car, but who knows when that happens. The reason I use car subwoofer is simple, I have been heard a couple of hometheater subs in shop and one in my brothers house, they sounded good, but still lacked the pucn I like and the major diffrence why I didn't chose any of them is because if I would just take a ready subwoofer and bring home into my room, it would sound so much diffrent from the shop or what my brother has, because diffrent type of room size, diffrent furniture and everything that affects the traveling of sound waves. I'm not pro of the whole concept of the audio, but I do know something, might it be right or wrong that I can't quarantee.

Thanks Ivan and Marjan, for your time to explain, but I have said that it's hard to know what is a correct answer in audio, there are many "old school flag carriers" who says what is the best design. I found plans of a reflex box which houses 15" drivers called housewrecker, but again there are no specified drivers to be mentioned, just use from 1 to 4 drivers and test what it sounds. Same for me to test that design out and if it fails, well at least I have fun with it.

Thanks to everyone who helped me in a way or another.

[ProSoundWeb Community]