# Poll - TRIO12 Butt Kicker Or TRIO12 Lease Breaker



## mwmkravchenko

Hello folks.

I'm working on two different horn designs that will be barn burners and lease breakers. I started working on them in June so this is not a me to Danley thread. These two offerings are legitimate front loaded horns. Not tapped horns. They both when loaded into a corner have response that will be just under 100db/watt. They will both be using one TRIO12. Here is the difference. The big boy is here:










Little boy is here:










The astute among you will notice my definition of little and big has a bit of a twisted sense of humor to it. Once folded into a real box they are 16 cubic feet and 9.5 cubic feet.

I know am I crazy. If you have to ask then it isn't obvious! Here is why I'm so crazy. Here is the maximum SPL for each box.










BIG BOY










LITTLE BOY

The ripples in the response generally clear out into the room wash. So don't pay to much attention to them. Both boxes are long enough that if you EQ them they will not readily go into over excursion. Both posted max SPL are done in 1 Pi space. This is on purpose I understand that .5 Pi is a true corner. But few of us have a completely reflective concrete corner to put this into. If you do strap on another 3db on top. Both simulations are peaked out at 18mm X-max. This driver can do a clean 20 and over excursion to 22mm. So there is room for a bit more than 2 db more. Add in room gain and these boxes are almost flat to 20hz and 16 hz. So these are some real contenders. Definitly not available commercially. Oh did I mention that with 100 watts they can crack 120 db! muhhahahahha:R:R:R:R:R:R:R 

Them that are interested vote. The one with the most votes is the one I build. This is a benevolent dictatorship after all!

Mark


----------



## BigHonu

That is some crazy efficiency!


----------



## Mike P.

If you can get 129 db at 22 hz in 9.5 cubic feet then I vote for the little one.


----------



## mwmkravchenko

BigHonu said:


> That is some crazy efficiency!


Yep!

But that is also why these types of speakers are so much fun to listen to. They are exceptionally clean in their low end reproduction. It is something that has to heard and gotten used to. But that being said they are in fact most lifelike.

The high efficiency works in our favor in that the horns track a signal that is very energetic much more quickly and cleanly than a vented or sealed enclosure. Just think how little cone movement is required to reproduce 100db! 1.5 mm. So yes there is the carzy big box. But some of the subs on the Shack are bigger and are strapped to kilowatt amps. This little babay beats them with less than a third of the power. The big boy even competes rather favourably with the Big Danley sub. With one less driver!

Mark


----------



## mwmkravchenko

What 66 views and only 1 votes! :huh:

Come on guys I need some dissenters and nay sayers as well as some votes.

Two people just don't have enough traction.

Mark


----------



## mwmkravchenko

For those who want to fool around with design ideas here are the input screens:

Mark


----------



## BigHonu

Forgot to vote!

I like the Little Guy. 

Horns/TL's have always interested me, as the level of performance that can be squeezed out of the system seems so disproportionate to more common enclosures. I would love to see how you end up folding this guy, and the in room response.


----------



## tonyvdb

I'm with Mike and Brian go with the little one:T
Thats some serious SPL:hsd:


----------



## tcarcio

The little guy is my choice also.......:T


----------



## mwmkravchenko

Thanks Mike for the Poll. I should have figured out how to do that before I posted.

Mark

P.S. I voted for the little guy to.


----------



## Bengoshi2000

The big boy... you could christen it "The Eviction-ator."


----------



## mwmkravchenko

Bengoshi2000 said:


> The big boy... you could christen it "The Eviction-ator."


Yeah Baby!

Now were talking. Even though I voted for the little one I must admit I'm contemplating the possibility of figuring out a fold for the Big Boy to. It's just to tempting. Just the bragging rights alone! 129 db at 16hz Yhoooow!

I built the UNHORN prototype to go down low enough in a car and it works great has moderate efficiency and great sound. But a real front loaded horn is a different animal when it comes to efficiency. 

I look at it this way. The smaller one could be put in a corner and stuff piled on top or what ever. It's not small but not enormous either. The performance is great. But it would be oh so sweet to be able to reproduce the low end all the way down to 16 hz without fear of blowing anything up. Can't make it much smaller but a creative fold could make it somewhat in form factor like the Danley SPUDS. Flat and narrow. That makes it a bit easier to stick in a basement and hide it in a storage or mechanical room and shoot it into the listening room. 

The smaller one I think is going to be a 48" x 16" by what ever it works out to box roughly 22½". The bigger one can go a couple of ways. Long and squareish ( I know it's not a word ) The Big Boy (Eviction-ator):devil: could work out like this: Say 15" x 24" x 94" long and low. Remember I make my boxes out of 1/2" material for the sake of box weight. If you brace it up properly there is next to no difference in rigidity and most materials like MDF for example are actually more rigid in the thinner panel. These prototypes will be made in OSB ( oriented strand board ) All glued and rabbeted in place and then braced up the wahzoo. All depends on the lay out saga to follow. That is always the most fun part. Fun like going to the dentist. If I had a dollar for every time I tried folding a horn I'd be a rich man!

Time to feed the little hamster that spins the wheel in my brain! Maybe I can come up with something useful on this one.

Mark


----------



## Ricci

I'm skeptical. 

The simulations that you have shown would perform similar to or in many ways outperform the Tom Danley designed Labhorn which is: widely known as a monster among the professional sound arena, is much bigger, uses a pair of 12" drivers with higher power handling and has a cutoff of about 35hz and an intended range of only 30-120hz. This would be accomplished with a single moderate power 12" driver in a smaller enclosure, with a smaller horn mouth and almost an extra octave deeper of loading that somehow is much more efficient as well? I do not see how this is possible. If this is true every prosound outfit in the world would be using these types of cabs and we would have 16-20hz extension at concerts. We don't. 

Also you have listed the power input as only 163watts give or take on the larger one, but your spl graph shows a gain of nearly 30db over the base, which is not possible unless the response graph showing about 105db at 100hz is for about 0.163 of 1 watt. Your 100hz efficiency would have to be about 113db at 1w and an astonishing 103.5 db at 16hz.


----------



## mwmkravchenko

Hi Ricci

It' good to throw in questions!

I'm working right now so I'll keep it short. 

Your power assumption has been mislead by how Hornresp works when doing a sample . It calculates the frequency, the SPL, and the power into the load that the driver presents at that frequency. So you probably agree that close to Fs any driver is not at it's nominal impedance. You probably understand that 600 watts into 4 ohms is a voltage dependant variable. The amp driving a 16 ohm load will drop it's output to 150 watts . This is what is happening at the sample points as they are either just above or just below system resonance for this driver.

On the subject of low end. It is mainly a function of horn path length. The mouth size will support the low end to a greater degree when it is larger. This is apparent in the roll off at the low end.

Driver choice is because it is an excellent driver for this type of enclosure. It is very well put together and has almost double the X-max of the Lab12. That is the reason why it can compete with 2 Lab12's.

There are more points to discuss but I'm typing on my phones tiny keyboard and my fingers are not tiny! I'll post some more tonight as well as a simulation with the Lab12 on the same horns for a comparison.

Mark


----------



## mwmkravchenko

Hi Ricci I'm just finished work.

Some more info. The power input for the smaller box is 500 watts for max SPL plot. The max SPL plot for the larger box is 300 watts.

Most important is this fact. These are simulations! Although I greatly respect this program in it's ability to model things accurately it does so using the real world converted to mathematical formulas. I posted most of the graphs into 1 Pi because that is the best I ever get loading a horn into a corner which mathematically is .5 Pi. In real life expect about 3 to 4 db less efficiency. So more or less 98 to 100 db/watt loading these horns into a corner.

I greatly respect the work of Tom Danley. His Lab horn is a tour de force in heavy duty low end horn design. But he designed it for exactly what you have described. Production sound. No one in a home is going to push their subs to the same limits of continuous SPL that you find in the Pro sound world. We are dealing with loud and very loud transients. That is the second reason why one well designed driver can get away with what is simulated. We at home will never on a continuous basis be pushing a horn as hard as in a Pro environment. How many times at a concert or medium sized venue can you actually get proper corner loading? The difference as you know is 6 db in gained reflection. That four times the power. So I design a little on the edge knowing that a bit more performance can be squeezed out at the risk of driver longevity considering no one will really be pushing the horn so hard that driver longevity would be an issue. Almost everyone that has a horn loaded sub at home mounts it in the corner. It is the optimum location and this horn is designed for the optimum location. Not in the open or like the LAB horn to be used in stacks of three or more.

One more point. I have been working designing and building horns since 1995. Not a really long time but long enough to have learned a thing or two. First and foremost that simulations are just that. Close approximations.

As an example I followed a novel box design simulation that started as a what if kind of idea. A little down the design path I posted the results in the Unhorn proof of concept thread. It is to short to produce the low end output that it showed when simulated. That is until you take into account the tapping effect that the driver placement creates. It effectively doubles the length of the enclosure . The pinch point creates not a horn load but a sort of bandpass enclosure effect. It is neither a true horn nor a true bandpass box but a hybrid. It simulated well and measured well albeit with the drop in efficiency of about 3 to 4 db between the simulation and the measurements that I have always come to find when translating a simulation into real life. Squeezing that last bit out from a real world design is an evil task I wish on no one. 

So much of creating a horn lies from the point of modeling to the creation of the actual horn. There is a real art to folding these beasts. And it is none to easy. I have been a cabinet maker for some 20 odd years. Not making kitchens but stuff furniture and fancy mill-work. And I have to admit to this that the Dual TRIO8 Unhorn took me three folds and almost a week of consternation. What Tom and other gents have presented is really good engineering. What I'm putting up here is an attempt at good engineering. The proof will be in the pudding.

This thread is a poll as to what some gents knowledgeable or just plain interested would think of either type of enclosure.

Below I simulated the two drivers ( Lab12 and TRIO12 ) in the smaller horn. At 1 watt and at 100 watts. Remember that this horn is designed for the TRIO12 and that is very important. The motors on the two drivers are very different in some respects as you shall see. One of the reasons why I chose 100 watts is because that is where the LAB12 runs out of excursion. The TRIO12 is just getting up to almost 1/2 speed at 100 watts. So taking this crude comparison two LAB12's would keep up with one TRIO12 in this horn. It would also allow a bit shorter horn path. But the overall volume would only go down slightly as the rear reactance annulling chamber would have to be larger with the two LAB12 drivers. The SPL would potentially go up by 3 db or double the power. But unfortunately 3 db is where normal untrained listeners just begin to hear a difference in SPL. So I'm not so sure it is worth it.










Mark


----------



## mwmkravchenko

I just ran the Butt Kicker through a simulation in AkaBak. It is a different program to simulate horn designs among other things. An interface from hell but it is quite accurate. When it looks good in AkaBak you have a decently close approximation of what it will sound like. Note that the program simulates the box in a 2Pi environment. That means outside on the ground. Inside against a wall with a floor and ceiling is 1 Pi and all the floor, wall, ceiling plus another wall to make a corner is .5Pi. Each boundary adds to the sound pressure level. So from outside to inside add 6db. Into a corner theoretically add 6 more db but in real life 3 to 4 db as not all corners are truly reflective at all frequencies. A basement you could call truly reflective if you are in a corner made with concrete walls.










Mark


----------



## Ricci

Mark,

Sorry I have been very busy. 

I understand that these are simulations and that the applied power is not a constant amount due to impedance fluctuations. Mainly my point is that most people model their bass response in a half space environment at 1m and this is what they are used to seeing. Adding the extra gain due to boundary reinforcement, which may or may not be fully realized in reality is confusing and makes the enclosure appear much stronger to those that may not be aware of what is going on in the 1/8th space simulations. 

Also normally the power input is specified as an amount that will not cause the driver to get into overexcursion at any point in the intended FR passband. Hornresponse is slightly irritating to me in the way that it keeps constant input power regardless of the impedance changes, so I understand where you are getting the input power from. 

Perhaps show the halfspace max output hornresponse simulation in order to better compare it with the more popular "normal" builds of ported and sealed enclosures. 

One final note is that the Lab12's actually do not run into excursion problems until well past 20mm one way. About 30mm inward seems to be the suspension "bottom". Limiting to 13mm is very conservative.


----------



## mwmkravchenko

View attachment 17442
Busy what's that!

Oh do I know what that feels like.

OK Ricci you must either be in Pro sound or have been in pro sound because you have a good grasp on whats going on. I have to admit I did not know the LAB12 was good to that level of X-max. But I have to work with something when I'm simulating sight unseen. They have to be grossly distorting at that level of excursion. From the modeling of the LAB12 that I have fooled around with the BL curve looks pretty nasty with that much excursion. But so does any other woofer as it gets pushed out of the X-max region unless it is an underhung motor design.

I did up the Max SPL within X-max for the TRIO12. It to can go beyond the stated X-max but from what I can remember not 30mm. If memory serves me correctly I think X-mech is 28 mm. Still pushing the limits for any driver to do this at length.

Below I post the results of the simulations. Happliy the horn is only -10 db at 20hz. So we all know what happens with decent room gain down there. The path length of the horn will support 20 hz the mouth will not. I chose the mouth size to give full loading to the vast majority of music and effects. It is well loaded down to 40hz. Below that depending on the locations of the boundaries the horn mouth is next to you should be able to get almost flat output down to 20hz ( with a good solid floor and corners )in the vicinity of 120 db with 500 watts input. The cool part is that with 100 watts your already blowing away most subs! The sad part is that from 100 to 500 watts we only roughly get an additional 7 db increase in SPL. The law of diminishing watts. I always find that after 500 watts you should just get more drivers if you want to go louder.


----------



## mwmkravchenko

I guess the voting thus far is three to one for the ahem.... smaller one!

It's a tough job running for votes and all that. But I'm guessing the people are speaking!

Mark


----------



## Binary

BIG... wait... thats not THAT big...


----------



## Ricci

Thank for humoring me Mark. I'm not really from Pro sound BTW, but I do have a little experience there. I just have an interest in sound period. BTW I'm one of the votes for the big one.


----------



## mwmkravchenko

Still waondering how come there are so many hits to this thread and so few votes?

Looks like 9 to 4 small to large. Well I'm inclined to think that this is going to be a toss up as to what I build. When I build I need some input as to form factor. You guys partial to as compact a box as possible or long and as slender as possible? I personally think long and slender has more possibilities to hide it away in the midst of furnishings or permanent installs. A over grown cube has all the grasefullness of a SUmo wrestler! No offense to Sumo wrestlers!

Any thoughts?

Mark


----------



## Mike P.

I agree that long and slender has more possibilities for ease of placement.


----------



## fredk

> Add in room gain and these boxes are almost flat to 20hz and 16 hz.


OK, that got my attention. I followed your unhorn thread with great interest and have done my share of reading on horns and tapped horns, but it seems that most designs are good to 20Hz. Yea, I know about the DTS 10, but its overkill for my space, probably very expensive to ship to Canada, and I would never get it out of my apartment when I move.

I already get a flat response to about 20Hz with my current sub with reasonable headroom, but I want another 5Hz extension to see what all this sub 20Hz excitement is all about.

Ignore the votes and build that large bad boy and show us what this driver can do. :devil: You know you want to...

Oh, I live in a concrete bunker (otherwise known as a concrete construction aparment building) so I might just get that .5 pi corner gain.


----------



## mwmkravchenko

Hello Fredk

You may be into a true lease break with thhe big box!

But I do have to admit I'm more than a little interested in seeing and hearing them both. It took longer to design the larger one because there are many more variables on a large format horn. More places to sqeeze out some volume. But I could only shave off so much before the response simulations really suffered.

I just have to convince some crazy guy that he needs such an animal and awawy we go!

Oh yeah and I have to work enough to pay my bills and be able to take the time to make these boxes.

Life always rears it's ugly head. And put's the clamps on creativity.:R

Mark


----------



## fredk

> just have to convince some crazy guy that he needs such an animal and awawy we go.


Hmmm... at 94" you can just stand this thing up in a corner with 8' ceilings.

You show simulations with 500w of power applied, but the driver specs show 350w rms power handling. Could you reasonably drive this with a 300w bash amp?



> You may be into a true lease break with thhe big box!


Well, I put Serenity on at 1:30am one morning at close to reference with windows rattling before thinking that maybe it was a little late to be playing a movie like this so loud. I thought for sure I was going to hear from the landlord. Not a peep. Living in a concrete bunker has some advantages.


----------



## mwmkravchenko

> Well, I put Serenity on at 1:30am one morning at close to reference with windows rattling before thinking that maybe it was a little late to be playing a movie like this so loud. I thought for sure I was going to hear from the landlord. Not a peep. Living in a concrete bunker has some advantages.


fredk you are a rebel! 

Here is my take on subwoofers and proper power setup. I go for an amp that can best the power rating for this reason. All speakers can take more power on peaks than their rated maximums. If you have a clean 5 kilowatt amp you'd be surprised how many speakers could handle a clean 1 to 2 kilowatt peak in the music. It's not the peak power that kills speakers. It's steady state overdrive or an amp that is being driven into clipping which unfortunately treats the speakers voice coil like a heating element on a stove. Poof is what usually happens. But other than launching a driver with to powerfull of an amp due to stupidity I have never damaged anything by having more power available than the rated maximum. 

So my advice after all that is go for the 500! You won't be sorry.

Mark


----------



## fredk

> fredk you are a rebel!


Not really. I'm still occasionally surprised at how loud you can go when your speakers play clean.

I guess I'm kind of the opposite from you. I go with as little as I can get away with. I get just what I need as long as it does not compromise anything.

My current sub has headroom on 300 watts and my thinking is that the horn's increased efficiency would provice the additional horses for the extended frequency.

So, what are the potential issues of a horn sub like this? All designs have strengths and weaknesses.


----------



## mwmkravchenko

"I guess I'm kind of the opposite from you. I go with as little as I can get away with. I get just what I need as long as it does not compromise anything."

Hi fredk

I'd lean toward being on the same side. It is the added box construction complexity that sqeezes the performance out of the driver to the highest point that can be attained. The power reccomendation is to enable you to get the driver to run closest to it's peak output. It will not bedriven past 18mm excursion with less than 500 watts due to the horns loading effect on the driver cone.

Granted at 100 watts this type of box will produce a higher SPL than any other type of box. 

But here are the trade offs:

Bandwidth.

A horn trades the width of reproducable sound for efficiency. If you mae a horn to cover say one octave from 20hz to 40hz (one octave is a doubling of frequency) it could be constructed to be even more efficient. A normally optimised horn is good over about 2 ½ octaves to 3. The two presented horns can do 3 octaves. With a subwoofer this is usually what we want. It becomes more of a problem only if we go into the midrange.

If you want to go low and loud.

A horn behaves just like a vented enclosure that is played below it's tuning frequency and causes extreme cone flap. The difference being in a horn where the beginning throat area is quite small the pressures generated are larger and will quickly shred a woofer.

Solution: 1 Make a horn that will play just about everything you want to in the first place. You need not worry if it can reproduce 16 hz. YOU KNOW IT can !

Solution: 2 Use a high pass filter to get both sides of the problem licked. If you filter out the frequencies below the horn's passband then you are doing great.

A bit more touchy on the EQ.

If you carefully think through the other lines about the high pass you can in addition to a high pass EQ any falling response to a box/driver combination. With a horn it is the combination of the horn path length and the size of the mouth that allows reproduction of the lowest frequencies. If you have a smaller compromised mouth opening you can still get decent low end from the horn if the path length is long enough. These two horns have a path length that has been designed to reach the low end as posted. As long as you respect the X-max limits you can EQ the horn in the frequencies above it's natural cutoff frequency which is 22hz for the smaller one and 16 hz for the larger one.

The maximum SPL curves have been posted that are very realistic. Not the pie in the sky corner loading with hoped for resulting awesome SPL graphs. If you have a truly reflective corner loading area you will meet or exceed the posted graphs. I have done enough horn design and physical construction of the horns using these two programs to trust them that much.

You get very dynamic sound. A draw back I know! those horns. Being so life like and all.

You get very low distortion. 

This may be one of the biggest I don't like the sound complaints. 

If you go to a lot of live non-amplified concerts or play music yourself you will like horns. They play it as it was recorded. If you are into rap and other artificially generated stuff you will quickly find out that a lot of so called bass is really drivers that are being driven into serious levels of distortion. A bass horn takes this stuff apart and the rsulting sound is not what you are used to. It is a night and day difference. A good well setup horn loaded driver will speak with authority that will smack you in the chest and then just fade to black if there is no low end to reproduce. It allows you to hear well played bass guitar, string bass, and the like. You can hear the difference in the notes, the attack in the upper bass gets cleaner. It simple is the closest way to hear what was at the recording venue. I usually test with huge pipe organ tracks that scare to heebie jeebies out of most people. 

Maybe Adam will post what he thought of the last round of testing.

For home theater effects you have reproduced what they recorded. On movies they are usually pretty carefull what they do. So you get good sound from good movies.

Hope some of this makes sense.

Mark


----------



## fredk

Wow, great reply! You've given me a lot to chew on.

So, if I understand horns, they allow a driver to more effectively couple with the air at the narrow end, and take advantage of the taper to amplify an expanding wave?



> A normally optimized horn is good over about 2 ½ octaves to 3.


The effective bandwidth of this horn would be 16-128Hz then? Is it a combination of the taper and the path length that determines the bandwidth?



> I usually test with huge pipe organ tracks that scare to heebie jeebies out of most people.


I like pipe organs!    In fact, that is one of the reasons I want a sub that will dig a little deeper. I want to hear/feel everything a pipe organ puts out.

So, if this horn is tuned to 16Hz, and there is movie content below 16Hz, does this mean that I will need a highpass for this sub?

Thanks for taking the time to explain this stuff Mark. I think one of us talked me into building this horn. :devil: Now I just need to figure out how the I'm gonna get this thing down 3 flights of stairs when I move.


----------



## mwmkravchenko

> "So, if I understand horns, they allow a driver to more effectively couple with the air at the narrow end, and take advantage of the taper to amplify an expanding wave?"


Think about a horn and driver combination like a lever and a fulcrum. A lever with a fulcrum close to one end lends the greatest mechanical advantage possible. An ideal horn adds the greatest amount of mechanical leverage to a driver. That type of horn is usually called a siren or burgular alarm type of horn. They are crazy efficient but only over a very narrow bandwidth. I remember reading a paper on a design that was 138db/watt. Poor sucker testing the SPL on that one!

I posted this a while ago in diymobileaudio and have posted a copy of it here:


From what I have come to believe in building and designing horns this is my theory in a nutshell ( albeit a rather big nut shell ).

Horns can massage more molecules of air per given movement of the cone than any other box configuration that I know of. Because they can do that they are more efficient than any driver directly radiating into a room or space. Because they do more with less they can also when properly designed do it it much less distortion. You just have to look at the cones in a horn when it is pumping out crazy volume and the cones are barely moving.

The explanation for this effect that I have read that makes the most sense and that I can attest to from my own observation is that the molecules of air that get vibrated or excited by the cone movement want to dissipate their little bit of energy. That is true with any driver radiating into any space. In a horn they have to do that with a very controlled amount of air molecules. Less close to the driver as the horn area is smaller there. These little air molecules are most energetic when closest to the driver and as they are pushed along because they are being corralled and herded by the horn structure from a very confined space to a more open space. The originally excited molecules of air excite more molecules of air on their way out of the horn. They loose a bit of energy from each exchange of energy molecule to molecule. But the greater the number of molecules that are excited to a higher energy state the greater the potential sound pressure level at the mouth of the horn.

We know from basic physics that every object acted upon by an outside force wants to dissipate it's energy and return to a state of rest. So all the excited molecules of air within that horn structure are a captive system that has a given mass of air within it. That given mass of air when excited by a driver wants to get back to it's resting point. So all that energy gets shot out of the mouth of the horn and it dissipates into the room. But the efficiency lies in the trick that a great big amount of trapped air within that horn has been driven into vibration by that loudspeaker cone. That is why the horn is more efficient. No directly radiating cone could ever push around as much air . That is also why when you simulate horns you usually find that the larger the volume of the horn the greater it's efficiency. It really Sucks because everyone wants a small horn that acts like a big horn. But a big horn with a few watts can blow away any normal box be it sealed or vented with much less distortion in the sound than any normal radiating box with even kilowatts of power behind it.




> "The effective bandwidth of this horn would be 16-128Hz then? Is it a combination of the taper and the path length that determines the bandwidth?"


The horns do a little better on the top end. In a long bass horn it is usually the path length and the number of bends that determine how high up the horn will play. You could expect around 200hz at the top with greater degrees of loss in fidelity due to reflections from the horn walls.



> "So, if this horn is tuned to 16Hz, and there is movie content below 16Hz, does this mean that I will need a highpass for this sub?"


It would be safer to be sure. And it will greatly increase the driver longevity using a high-pass.

But consider this bit of info:

On a pipe organ the lowest usual stop on a large pipe organ is 32 feet at it's lowest C. It sounds around 16hz. One octave up or the 16 foot rank you are getting the low C sounding at 32hz. Taking a normal 12 notes per octave counting sharps you are getting one note every 2 2/3rds hz. The difference from the 16hz sub to the 22hz sub is what 2 1/2 semitones? Not a lot. The size difference is substantial. The worst part is that when you are actually at an organ console and you draw out a 32 foot stop all by itself you don't get a lot of a lot of profundity! When you draw out a 16 foot stop and a 32 foot stop in tandem then you are rocking. What happens is an effect where the lower pitched stop modulates the higher pitched stop. The modulation occurs at the frequency of the note played on the lowest pitch and voila you get that awesome bass response. But the fundamental is also much more quiet than the harmonic. The true effect is much louder harmonics. ( The fundamental is the lower note. A harmonic is any multiple of the fundamental. For example a 1st harmonic of 16hz is 32hz a second harmonic is 64hz a third harmonic is 124hz) All this crazy explanation to tell you how little it will really mean going down another 7hz!



> "Now I just need to figure out how the I'm gonna get this thing down 3 flights of stairs when I move."


What no windows?
Bungie cords, parachutes. Come on this is DIY after all! :rofl2:

I think I have to build it first. Trouble is I'm to busy trying to make a living in the big bad world. Spent the whole day fighting with a front wheel bearing on the car that is supposed to take me to work. To poor to pay a tow truck and a mechanic. I love cars. That is when they work. Something like I love computers. Sometimes :sarcastic:

I love them when they help me design loudspeakers! And test them.

Mark


----------



## fredk

> What no windows?
> Bungie cords, parachutes. Come on this is DIY after all!


Actually, I already have a temporary post and pully setup for hauling my canoe up and down. Gave the building owner a minor heart attack. Its only 50lb though.


----------



## mwmkravchenko

> Actually, I already have a temporary post and pully setup for hauling my canoe up and down. Gave the building owner a minor heart attack. Its only 50lb though.


:R:R

Never say can't!

Mark


----------



## fredk

But sometimes its good to say shouldn't. my cross beam is held against the balcony ceiling by preasure when its set up and I have had it slip a little twice now when hauling the canoe up. It might work if I used both verticle posts to increase the preasure againstthe cross beam, but still...

What material do you usually use for final builds on your horns? Baltic Birch seems to be the recommended material, but as I understand it, the good stuff only comes in 5x5 sheets.


----------



## mwmkravchenko

> What material do you usually use for final builds on your horns? Baltic Birch seems to be the recommended material, but as I understand it, the good stuff only comes in 5x5 sheets.


Depends where you live and where you can buy your material. I can get Baltic birch plywood in 4' x 8' panels. The only difference being that they are of the dirty blond heartwood not the creamy white sapwood. 

But if you are determined you can take almost any panel and make it the equivalent with properly spaced stiffeners. For large prototypes I usually use 7/16" OSB or wafer board. The stuff is incredible dense, cuts well and when I brace it up it works well. If you put the time into sanding staining and varnishing it you can actually have something that looks rather beautiful. Oh yeah and it's a whopping $8 / sheet! So each to his own poison. If I were to build the box for permanent install I see no problem using OSB. If it is going to be moved around a lot then a better quality plywood. If you like Baltic birch then great. But it is heavy compared to other plywood. And the cost will go up substantially.

Mark


----------



## fredk

Hmm. All the discussions I have seen around materials talks about MDF or BB ply. I even remember one thread where the original poster was told to rip out the OSB he had used for part of the project and replace it with BB.

I presumed that materials like OSB have poor acoustic properties due to their lower stiffness and density.


----------



## mwmkravchenko

> I presumed that materials like OSB have poor acoustic properties due to their lower stiffness and density.



A simple search on the properties of different panel materials is quite enlightening. Next thing to add to the mix is that a brace on a panel adds stiffness. A through brace from top to bottom and side to side improves stiffness geometrically.

Modern construction grade OSB is actually more dense than most plywoods. I don't have the tables at hand but I'll hunt them down.

At any rate your completely free to choose what you wish.

Mark

Added this link:

http://bct.nrc.umass.edu/index.php/...ing-between-oriented-strandboard-and-plywood/

http://www.resfreq.com/usefulinfoonwood.html

The lower link has a lot of good ideas.


----------



## fredk

Thanks for the links. I have read about a number of materials, but never found anything speaker related on OSB. The suggested construction methods in the second link fit with what I have read but he adds OSB as a material.


----------



## mwmkravchenko

I'm keeping an eye on the poll and I'm starting to think you guys might want both designs. Like I don't have enough stuff to do! One or two votes either way will bring it closer than some elections.

I just have to remember. A sub-woofer in every home and a home in every sub-woofer. Hey wait a minute. I could combine the two! A sub-woofer big enough to live in. Yeah that's the ticket. Infinite low end. Complete domestic tranquility because location is not an issue. It's one half of audio heaven.

Yep and then I woke up.

I think I have to get busy and hammer out the designs for these monsters and see how close to the simulation I can convince reality to grant me on the first fold attempt. 

Mark


----------



## fredk

Well, I'm quite serious about building the eviction-ator if you will do up the design. I have the week between Christmas and newyears off so I will have the time then. I figure I can cut the parts in my dad's garage and clear my livingroom for assembly.

I have a question for you about the hornresponse model. What do the peaks and dips mean? I notice in your model that they show up all the way down below 20Hz, where as in other models I have seen, they are relegated to the region above 90Hz.

Is there somewhere I can read up on hornresponse?


----------



## mwmkravchenko

Hi fredk

Just a little bit busy these past few days. Here is a link to some items of interest regarding Hornresp. I have to warn you it is a toough learning curve. But once you have the basics it is a very powerfull program.

http://www.diyaudio.com/forums/search.php?searchid=464695

As for building over the holidays. Sorry bud. That's when I'm going to try the prototypes. So I can't post anything that I don't have. I'm thinking of messing with two drivers instead of one. For beginners it is 3 db better in efficiency and it will change the horn a bit. When I have crunched the number I'll post it and see what you guys think. Louder is always better. 1/2 the distortion is better still. So I'll see what I can come up with.

Mark


----------



## mwmkravchenko

Hey fred did you build the sub you were talking about in the thread about speaker physics? That would be a hard act to follow.

Mark


----------



## mwmkravchenko

OK Now I've been a fooling around. I should have done this from the beginning. 

Two drivers provide quite a few benefits. The great thing about computer simulations is that I don't have to make saw dust and big boxes to change things around. I posted the latest and greatest below. The SPL simulation is done in the nasty AkaBak. It is not nice to designs that are not good. The most hopeful thing is the low end rolls off almost perfectly to take advantage of moderate room gain in the lower end. The power input is 100 watts. Well under X-max at 12 mm. Take note that this is in a 2 Pi environment. In a house the low end will be much much better. And Oh yeah it is almost the same size as the other large box. So Big boy still applies. I'm working on a smaller version with more or less the same volume of the smaller one. It's about 190 liters. but much more efficient on the low end. Which is why anyone would build such a monster box in the first place. 

I just added the smaller horn. It is indeed smaller. The short story is that when you use more surface area as in cone surface area you can effectively shorten the horn almost to the point where it is equal to the surface area of the driver cones. It works well. You get more output and a smaller box. You loose more money because you have to buy another driver. But you get jaw dropping efficiency. The smaller horn is again posted at 100 watts power input two drivers in series. If you have the power capability you can wire them in parallel and then get even greater gain in electrical efficiency.

Mark


----------



## fredk

mwmkravchenko said:


> Hey fred did you build the sub you were talking about in the thread about speaker physics? That would be a hard act to follow.
> 
> Mark


Sadly no. Every time I have the funds in place something new happens. The last one was my receiver frying in a thunderstorm this summer. That was bad news/good news because it allowed me to upgrade to an HD capable receiver, but pushed out my plans for building a sub.

I like the idea of a horn sub because it reduces the cost-of-entry and significantly reduces power usage. Just trying to do my bit for the environment.

If space is not an issue, it seems a horn sub has a lot of advantages.

It looks like adding a second driver extends the bottom end below 15Hz. Do you think having a second driver would eliminate the need for a highpass filter?


----------



## Mike P.

> Two drivers provide quite a few benefits. The power input is 100 watts.


The graph shows 96 db at 20 hz. Is that correct?


----------



## mwmkravchenko

Hi Mike

The graph shows a dip there. The dip crresponds to 96 db as you stated. Real world measurement almost never shows up such dips. The simulation for the dual Trio8 showed a similar response. What I measured was near flat to box Fs. That is what I'm expecting with these horns. So bump that figure up to around 100 db or a bit better. The other thing to note is that this is simulated outside on the ground against one wall. A truely reflective corner will raise the numbers by 12 db. And I haven't posted Max Spl yet. I'll do that tonight. This horn is not only smaller than the first ones it is also better than twice as efficient. 

You might have noticed the larger chamber at the beginning of the horn. This is an area where some experimentation could yeild the greatest changes.

Again keep in mind as with all sub-woofers this one with the designed roll off is almost flat with room gain.

Posted response in tandem with a good Eq will allow flat SPL at insane levels. That I promise to play with. Gotta get me one of those fancy DSpeaker dohickies!

Mark


----------



## mwmkravchenko

Well a little time behind the keyboard and I have some interesting things to post. I have two boxes that are quite a bit smaller. I have a 1 watt SPL that is close to the other boxes and slightly higher at a maximum SPL.

The mouth hitting the floor graph is for a horn to kill all others. It is a conic derivation of a true hyperbolic exponential horn. In other words as close to a curved hyperbolic shape as you can get using flat surfaces. It is crazy efficient. All SPL's in this post are at one watt. But the size! Calculate this and you get a meager 156 cubic feet! :yikes: Any takers I'll e-mail the particulars. :coocoo:

The other boxes are more house friendly. Again the one going down lower is the Big Boy. It has been shrunk to 10.4 cubic feet plus the enclosure. So about 13 cubic feet when made. With a bit of proper corner loading it would be near flat in room. A bit of EQ could tame the last bit of problems as with most subs. A high pass filter would greatly increase the upper SPL limit. I modeled over 125 at 22hz if you have a steep high pass at 25hz. That's with 500 watts.

The Little Boy is now not all that bad. It comes in at 5.8 cubic feet internal volume and just under 7.5 cubic feet as a built enclosure. 

All in all I think that throwing in a second driver has provided a good cost to benefit ratio. It will allow smaller boxes and slightly higher SPL levels.

Now to the last pic. The equal loudness contours. The equal loudness curves are what we hear. They are not ruler flat mechanical measurements but the normal loudness levels normal people consider equal at different frequencies. Take a look at them and you quickly notice from the first line the threshold of hearing at different frequencies. The just audible SPL for 16 hz is about 92 db. If you listen to music that is loud, peaking out around 95 to 100 db for the subs to keep up you have to be pumping out what 125db to 130db! That is an interesting bit of info.

Not to many subs can pull that off. ( 125 - 130 decibels ) These can. And at power input levels that are possible without breaking the piggy bank. :T

Mark


----------



## mwmkravchenko

Hi Fred

If you are intent on taking a kick at the can I can give the raw data that I'm working with. It looks a bit daunting but with some explanation it can be worked into a horn lay out. If you are interested let me know. Also please choose your poison. Large or small.

Mark


----------



## fredk

Thanks Mark. I still like the idea of a single driver version of the big guy. Won't have any time to do anything until after the 24th. Too much work.

The Hornresponse link you posted is broken by the way. I did a search and some reading over at diyaudio. I begin to see why it can be a challenginh program to learn.


----------



## mwmkravchenko

OK Fred drop me a line when you need the info. Or if you want a head start just say so. Remember though you are going to get a sheet of numbers that describe a horn in increments of 4 inches and the resulting cross sectional area at each 4 inch interval. To make matters even better the program spits out the info in metric. So sharpen your pencil and break out your calculator!

Mark


----------



## fredk

> So sharpen your pencil and break out your calculator!


:yikes:
I vaguely remember tossing my calculator out the window as I left my very last math class. This could be interesting.


----------



## mwmkravchenko

Hi Fred

I too have a calculator collecting dust. But I bought one that can do the algebra directly! TI 89. It's more powerfull than the computer I learned to do programing on! Crazy computers. When you need the info I'll try to be as explicit in the explanation as I can. You hope!

Mark


----------



## mwmkravchenko

Hi Fred

You want some numbers?

I have been refining the design a bit and I think I can release the raw data.

I also have a 4 driver design that is to scary to post. 4' x 8' x 3' definitely a build in place box.

Mark


----------



## fredk

Hi Mark. Yeah, I'll take the numbers now. Sorry I didn't get back to you over Christmas. I ended up being a lot busier than expected. I FINALLY got around to doing a little more reading on horn subs in the last couple of days.


----------



## mwmkravchenko

Ok Fred you want them publicly or privately? I'm not sure to many guys are interested in looking at 80 lines of numbers. 

Mark


----------



## fredk

Will this be in a form I can import directly into hornresponse? 80 lines is not a big deal, I can type very fast. Its just that accuracy is not my strong suit. 

On another note, some people over at avsforum put together a couple of tutorials that look like a nice start to learning the program and I don't have to sift through pages of posts for information useful to me as a beginner. I'm looking forward to playing with this.


----------



## fredk

Well, I managed to load the driver's t/s parameters into hornresp and actually model a tapped horn. Looked ugly as and I have no idea what I am doing, but at least I figured out how to get data in in a meaningful way.


----------



## mwmkravchenko

Hi Fred

Sorry for not answering. I've been running around like a chicken missing it head! Only country folk know that one! I can send it as a file that you can import into Hornresp. That will make it much easier I think. I can give you some pointers but you will be on your own for folding it. 

Mark


----------



## fredk

Hi Mark. I figured you were a little busy. Sure, send it as a file. Actually, if you post it here, others can grab it and play if they want to.

I'm still not sure about a bunch of things in hornresp, but I've been playing again tonight and its starting to make a little sense.

I have a question for you though. Some of your t/s parameters are quite a bit different than what CSS posts for the trio 12. For instance you show BL as 24.77 where CSS lists it at 14.9. Thats a huge difference.

When I double click on sd in hornresp and accept the entered parameters, it shows fs as 36.7 Hz vs 22 at CSS and vas as 27.4 litres vs 97 on the CSS site. Again, those are huge differences.

I put the CSS numbers into hornresp (I think :dumbcrazy: ) and the driver models very differently.

Oh yea, there was a question in there somewhere... So, did you measure your Trio12 to get the numbers you entered into hornresp?


----------



## mwmkravchenko

Time for a slight breather. Been mucho busy. Ok Fred

Yes there was a typo on the input of one of the designs. No it did not make much difference. Yes I do test them as I have them. I will post below the specs for one of the TRIO12 drivers I have in stock.

And I have posted the latest and greatest with one driver with the measured specs used to do the calculations. I also used the measured specs for the dual horns which I'm gonna build in the next little while.

Mark


----------



## fredk

Hi Mark. Thanks for the files. I've been so busy with work I havn't had a chance to do anything with them as of yet. 

Have you gotten anywhere with your build yet?


----------



## mwmkravchenko

Busy would not be in my vocabulary this month. How about running like mad! 

Almost done a job from he double hockey sticks. I will have time to work on this beast in a couple of days. And I have some clients to keep happy to boot. No rest for the wicked I guess. If you need any pointers don't be shy.

Mark


----------



## mwmkravchenko

Ok now things are getting back to their normal hecktic pace. This I can handle. So I will knock off a smaller version of this horn as it has the most votes. If all works according to plan and measurement I will build the bigger one. But that one I have no where to put. Maybe someone wants a killer sub horn?

Any other requests before I commit this to wood? Or are we all waiting for the measurements?

Mark


----------



## Mike P.

We're all waiting to see what the results will be. You definitely have my attention!


----------



## mwmkravchenko

Hi Mike

The larger dual TRIO 12 horn will come in around 17" x 48" x 30" 14.2 cubic feet

The smaller dual TRIO12 horn will come in around 17" x 32" x 23" 7.3 cubic feet

I'm usually pretty close to the sizes I spec at until I commit them to a full size drawing. Then I get into the nitty gritty business.

So some roofing grade OSB for a prototype or two and I will knock off a couple of enclosures over the next week and a bit. Can't wait!


----------



## fredk

> Any other requests before I commit this to wood? Or are we all waiting for the measurements?


Seems we are all waiting, including me.

I've been reading everything I can on horn subs and am curious to see how thoses modeled ripples play out in the real thing. From looking at other builds and design response vs real response, it looks like hornresp is pretty accurate.

On a practical note, how smelly does osb get in an enclosed space? Being in an apartment I cannot easily move stuff back and forth between a workshop and my living space. I would have to construct anything at my dads place and transport it back to my apartment.

My project for this week is to figure out how to fold a horn.


----------



## mwmkravchenko

> I've been reading everything I can on horn subs and am curious to see how thoses modeled ripples play out in the real thing. From looking at other builds and design response vs real response, it looks like hornresp is pretty accurate.


There are a ton of opinions out there by people who have been arm chair quarter backs. Those that have built what they simulated including me attest to the overall accuracy of Hornresp. But as for the dips I have never heard nor measured them. In practice everything seems to smooth out to the peak levels when you measure in room. If you do a true anechioic measurement outside up in the air yes you will see some of the dips. But even an outside ground plane measurement will not show them up.

So no I'm not to worried about it.

I am worried about one thing I sent your way. The throat area in the horn I posted is to small. I never post all the design tweaks as it gets to crazy for anybody to follow. Short story try a bit of manipulation to the tune of 120 cm². Then manipulate the area behind the woofer. The volume of air behind the woofer acts like a shock absorber does on a car. It dampens the oscillations the horn has because the mouth is grossly undersized. When you balance the two you get a much better response in the low end.



> On a practical note, how smelly does osb get in an enclosed space? Being in an apartment I cannot easily move stuff back and forth between a workshop and my living space. I would have to construct anything at my dads place and transport it back to my apartment.


OSB smells???

Yep I think it does to. But not that bad. Paint it and you will have the stench of paint to deal with not OSB. I guess it's choose your poison. I'm using the roofing grade as it is quite a bit more dense. I'll post the construction pics next week as I get to it. You will be able to see some of my sneaky little tricks I have used for years on horns. Been building them since 1994. Some of them even work well!

I'm hopping I will not have to go through to many cut and tries before I get what I want on this one. The last one was three attempts before I got the whole thing worked out. That is a combination of optimally small fold and driver placement that works well. But the Unhorn is a bit different than a front loaded horn. Driver placement is much easier with a front loaded horn. 

Mark


----------



## fredk

> I am worried about one thing I sent your way. The throat area in the horn I posted is to small. I never post all the design tweaks as it gets to crazy for anybody to follow. Short story try a bit of manipulation to the tune of 120 cm². Then manipulate the area behind the woofer. The volume of air behind the woofer acts like a shock absorber does on a car. It dampens the oscillations the horn has because the mouth is grossly undersized. When you balance the two you get a much better response in the low end.


Thanks for the tip, I'll try that.


----------



## Ricci

Mark,

In looking at your HR inputs on the first page again i noticed that your rear chamber sizes are incredibly small at only 6-14L in size! Also your compression ratio is upwards of 10 to 1! :rubeyes: I don't see how the driver could be made to fit in a space this small or survive the pressures. I guess anything is possible, but this is a LOT of stress on the driver and well outside of what a lot of people would recommend.


----------



## mwmkravchenko

> I am worried about one thing I sent your way. The throat area in the horn I posted is to small. I never post all the design tweaks as it gets to crazy for anybody to follow. Short story try a bit of manipulation to the tune of 120 cm².


I posted that in Post 67.

The design has gone through 18 seperate simulations. Each cross simulated in AkaBak. I have done enough simulations and builds to have a good handle on what gets carried over to the real world response.

Second point is that there is nothing the same from first to last simulation other than the response graph! Both boxes are significantly smaller and have higher SPL headroom than first posted.

Mark


----------



## mwmkravchenko

Hi Josh

I'm back home now.

The current horns have a 1 to 7.5 compression ratio. That is definitely not tough on the drivers. The rear chamber to facilitate reactance anulling is 35 litres. Everything will fit. There are about 28 litres in a cubic foot by the way. It's one thing to post graphs and such. Completely another to make such a beast sing correctly. With the amount of fooling around I have done on these two I'm pretty confident that they will work out well. 

Mark


----------



## fredk

Hi Mark. I've been playing and I think I'm starting to understand hornresp. I managed to get a respectable looking tapped horn for the trio12. I'll post what I have in a couple of days for your perusal.

I also gave a go at modifying the model you gave me but so far I've just been able to make the response get ugly. I think what you gave me has different tapers for different sections??

Here are some things that seem to make sense to me now.

1. horn length determins the low corner
2. expanding the horn size for a given lenght and expansion rate increases efficiency and thus output down low.
3. Throat size affects compression and how smoothe/lumpy parts of the response are
4. um... OK, I keep forgetting to document as I go along. I'm sure I figured other stuff out, but...


----------



## mwmkravchenko

Hi Fred



> I also gave a go at modifying the model you gave me but so far I've just been able to make the response get ugly. I think what you gave me has different tapers for different sections??
> 
> 
> 
> Yep there are different taper rates for each section. Actually there is 4 different sections.
> 
> Your findings are spot on. And yep it is hard to mess with a model and get it to look better without knowing a bit of what does what. I'll post another single driver horn for you tonight. Personally I'm going with the dual driver. Much better response in a much smaller package. It also allows more headroom for what we are all interested in the first place. Sound!
> 
> Mark
Click to expand...


----------



## fredk

Thanks Mark. At this point, I'm not sure what I would go for. I'm content to play with hornresp so I can understand what is going on. Who knows, I may actually figure out enough that I can come up with a reasonable design on my own.

In the back of my mind I have the idea that if I had to resort to two drivers, it would make sense to put them in two cabs that could also help with smoothing response in the seating positions.

Another question for you. Someone commented that when you see a lot of ripples in the response that it indicates a lack of motor strength for the model being applied. Is this in part what we are seeing with a single trio 12 front loaded? I notice that the dual driver unit is quite smoothe in comparison.

Note: this is not a criticizm of the driver, just trying to get my head around what is happening.


----------



## mwmkravchenko

> In the back of my mind I have the idea that if I had to resort to two drivers, it would make sense to put them in two cabs that could also help with smoothing response in the seating positions.
> 
> Read more: Poll - TRIO12 Butt Kicker Or TRIO12 Lease Breaker - Page 3 - Home Theater Forum - Home Theater Systems - HomeTheaterShack http://www.hometheatershack.com/for...lease-breaker-3.html#post231601#ixzz0eFQCCJdq


Hi Fred

The idea that two boxes will equal better response has a great many caveats behind it. The greatest problem is the room you are putting your sub-woofer into. If it has deep nulls in it's response due to the shape of the room nothing will really help. If it is more or less a large shoe box in proportion you could benefit from a second sub. But we are not talking by a huge amount. We are talking a benefit of 3 db with a second box or a second woofer. There is an argument that the two horn mouths can mutually couple and you get a better bottom end but again room position for the sub could equal or better that. For good low end the place where the sub speaks is almost as important as the box and driver choices.



> Another question for you. Someone commented that when you see a lot of ripples in the response that it indicates a lack of motor strength for the model being applied. Is this in part what we are seeing with a single trio 12 front loaded? I notice that the dual driver unit is quite smoothe in comparison.
> 
> Read more: Home Theater Forum - Home Theater Systems - HomeTheaterShack - Reply to Topic http://www.hometheatershack.com/forums/newreply.php?do=postreply&t=23002#ixzz0eFRIouAb


I really beg to differ on this supposition. Below I'm posting the complete info on a perfect sub using a single TRIO12 woofer. It is enormous as it is a true 1/8th corner horn design. But there is little to no ripple. The driver is very well balanced for use in a horn like this. It is not the greatest for a tapped horn as they like to see a driver with greater mass in the cone to work well.

If that statement about the driver were correct it would give you a rippled response on every situation. Indeed it can be true for a very under engineered woofer motor. The TRIO 12 is anything but under engineered. I've been playing with a couple for almost three months. They are excellent drivers. For the money they are in a class all by themselves.

What the ripples are is simple. They are caused by the program calculating the reflections within the horn due to the fact that the mouth is grossly undersized. Take a good look at the size of the mouth in the perfect corner horn example. Reduce the size and watch the ripples grow.

As I already posted the ripples do not make it into the real in-room response unless the horn design is grossly under engineered. You have the luxury of watching a somewhat seasoned pro work on a horn loaded sub-woofer. There is no new ground being broken here. I'm applying tried and true methods to get the most from the least. I don't post every little design change I make or every little discovery that I simulate. But I will post some response graphs and hopefully a critique or two in the not to distant future.

Mark


----------



## fredk

> You have the luxury of watching a somewhat seasoned pro work on a horn loaded sub-woofer.


I know that and its why I ask you questions.



> The greatest problem is the room you are putting your sub-woofer into. If it has deep nulls in it's response due to the shape of the room nothing will really help


Yup. I've done my homework on room response and done quite a bit of measuring with REW. I have a null at 72Hz and a huge peak at 56Hz that multiple subs will not deal with, but there is still considerable variation in response at the three seating positions in my room. That is what I want to smooth out with multiple subs.

I have another question for you. :bigsmile:

I have seen you post designs with high compression ratio and you have talked about drivers being able to handle it. I have also seen it mentioned elsewhere not to worry about a slightly high compression ratio because it only reaches that high compression approaching Xmax. Is that correct? 

I have no idea how hornresp calculates compression and I wonder about the Xmax statement because we do not enter it anywhere in the program. Hmm... now that has me wondering...

Anyway, thanks for the help Mark. I really appreciate it.


----------



## mwmkravchenko

Hi Fred 

Long day done.



> I have seen you post designs with high compression ratio and you have talked about drivers being able to handle it. I have also seen it mentioned elsewhere not to worry about a slightly high compression ratio because it only reaches that high compression approaching Xmax. Is that correct?
> 
> Read more: Poll - TRIO12 Butt Kicker Or TRIO12 Lease Breaker - Page 4 - Home Theater Forum - Home Theater Systems - HomeTheaterShack http://www.hometheatershack.com/for...lease-breaker-4.html#post231701#ixzz0eL5FuRd2


Generally compression ratios above 10:1 are pushing drivers hard. Literally the driver is seeing a much higher air pressure against it's cone than it was designed for. It is not really 10 atmospheres or around 146 pounds. But it is quite a bit higher than a sealed box pressure as there is not much area for the air to rush through so it tends to compress before it gets out of the horn. Not good for driver longevity. 

I usually try to stay at less than 10:1 ratio. The horn I posted quickly was quite a bit higher. That's why I gave you a heads up on some of the numbers to play with. The current final design for the two boxes is 7:1 compression ratio. No real big deal. I have seen successful horns with 13:1 compression ratios but it really depends on the driver being used. The TRIO12 is tough enough for the purpose. If the ratios are severely mismatched the driver will get shredded in no time. 

Hornresp will give you the compression ratio when you have your cursor over the throat size. It shows up at the bottom frame where all the info gets posted. I think David has done a wonderful job of creating a rather accurate program that really does predict quite well how a horn will behave. He has not incorporated automatic X-max calculation into the program because I think he gives the operator greater credit for knowing where X-max is in the first place. I mean come on if you can get the program to spit out a good horn design how hard is it to keep track of X-max!:unbelievable:

You know David is releasing a tool for horns to be designed just like he did for tapped horns? Sometime in the next week if I remember correctly. There is a dedicated Hornresp thread in diyaudio subwoofer forum.

Mark


----------



## mwmkravchenko

Holy poll Batman!

I haven't been paying enough attention to the poll lately. Everyone wants the little one. Ahem smaller one.

Do you gents think I should adjust the sizes to reflect what is actually going on or is bigger and smaller enough. They are both at least 2 cubic feet smaller than that posted. I also doubled the original driver complement to push this horn around a bit more. Gives greater umph! Afterall this is for the music right. I like the crazy organ stops that sound off like tuned jack hammers. Finally I will get to hear them at concert levels again. Been a long time since I built the monkey coffin with 5pcs 15" woofers and tuned it to 9 hz. Actually that was a bit bigger than a monkey coffin it was 16 cubic feet. I did my first LLT in 1997! Just wanted something I could actually feel ( I mean hear ) a 64 foot stop on a couple of recordings I had. I think we all enjoy good movie special effects. And there has to be at least one person out there who enjoys a bit of rock and roll. 

Mark


----------



## mwmkravchenko

Anybody ever try to use closed cell foam to build a woofer box? I got this crazy idea to use foam insulation sheeting and some 1/8th" plywood on the larger panels. I think if I do it right it will bee stiff yet light. I always build the battleships. Time to try something that is a bit better purpose engineered. Lighter to take over and get Adam evicted. After all this is the evictionator right?

Mark


----------



## mwmkravchenko

Ok voting is done.

Hands down the smaller box is the one that is going to be built. So this thread to is closed. Stay tuned for a build thread for the first generation of the Boominator. Hope the first will work out as specified. Sometimes it does. Sometimes I have to do this more than once. Oh the joy of designing horns!

Mark


----------

