or Connect
AVS › AVS Forum › Audio › DIY Speakers and Subs › the HouseWrecker. 11hz Twin CVX-15 Tapped Horn
New Posts  All Forums:Forum Nav:

the HouseWrecker. 11hz Twin CVX-15 Tapped Horn - Page 8

post #211 of 417
Quote:
Originally Posted by dB-Kicker View Post

Side note - I have room for four......

Do it! Or at least do two...

I remember the first time I had my first TH up over the 125dB mark at 1M and got up close to it. Quite a memorable feeling. Don't remember feeling giddy, but I do remember being a bit wobbly on my feet standing up again. I can only imagine 130dB+.
post #212 of 417
Thread Starter 
Quote:
Originally Posted by Oklahoma Wolf View Post

Do it! Or at least do two...

I remember the first time I had my first TH up over the 125dB mark at 1M and got up close to it. Quite a memorable feeling. Don't remember feeling giddy, but I do remember being a bit wobbly on my feet standing up again. I can only imagine 130dB+.

140dB at 25hz is so intense, it leaves people with a feeling similar to getting off a roller-coaster. That rush of adrenalin leads to elation and excitement in most people. Was a pretty fun day - and one I needed.

Some said it was the most intense thing they had ever experienced. Most couldn't take it for more than a few moments..

I used to want to reach 120dB clean at 120........

Dangit MIKE!
post #213 of 417
Thread Starter 
Quote:
Originally Posted by LTD02 View Post

kw, no prob.

db-kicker, are there any pics of the truck build in situ?

Friend me on face Book. I'll add you - you can see them there.
post #214 of 417
Thread Starter 
Quote:
Originally Posted by Oklahoma Wolf View Post

Very sorry to hear about this - I can relate, as I lost my grandfather to the disease. My thoughts and prayers are with you and your family.

Thank you Sir.
post #215 of 417
Quote:
Originally Posted by dB-Kicker View Post

140dB at 25hz is so intense, it left people with a feeling similar to getting off a roller-coaster. That rush of adrenalin leads to elation and excitement in most people. Half the company had to come through the room and play. Was a pretty fun day - and one I needed.

Some said it was the most intense thing they had ever experienced. Most couldn't take it for more than a few moments..

I used to want to reach 120dB clean at 120........

Dangit MIKE!

148dB in the van @ 25Hz leaves me wanting much much more
post #216 of 417
why not just go for 160 at 20hz and call it a day?

I kid I kid... (no really someone should do this! especially in a house!) lol


Matt
post #217 of 417
Quote:
Originally Posted by Steve_Vai_rules View Post

why not just go for 160 at 20hz and call it a day?

I kid I kid... (no really someone should do this! especially in a house!) lol


Matt

My initial tune was 15Hz with 110 cubic feet airspace and a 4' port, I was hoping for 50's
post #218 of 417
Best wishes for your father Deon and I look forward to reading about the HT build whenever you guys have chance to get back to it.

>120db at 16hz outdoors is a little weird.
post #219 of 417
Thread Starter 
Thanks Ricci,

He passed Dec 9'th.

Decided it was high time to get back to theHouseWrecker after a lengthy hiatus.

Lil-Mike once again cooked up some serious magic mojo TH wizardry. We went through 5 design rev's and stopped re-hashing it at 5.1a. That doesn't half cover the stuff Mike didn't toss my way.

So, long story short. We decided not to cut a hole through to the garage. Split the sub into two. Bring them completely into the room. He also let the sub tell us it wanted to do in the way of bottom end.

Mike learned a TON of stuff working on the layout -and we came up (he mostly) with something buildable - and I think unique in the world of TH's, this one includes a compresion chamber and is a 3d fold. (See pix).

Started cutting wood this weekend before I caught a nasty bug. Should see some progress there this week.. I’ll attaché a few sketchup shots.

I should edit the title to something like ‘theHouseWrecker’s. 13hz twin single CVX-15 cabinet’s’.

We’ll drop more detail on the thread this week, along with build photo’s, etc....

May have measurements over the weekend. Depends how far I get.

84 x 37 x 18 external dims.

90dB 1 watt@ 15hz, single cabinet.

3dB down 13hz relative to the rising slope.

10dB gently rising response to from 15 - 100hz.

125dB w/2kw PIN above 15hz, both cabinets, theoretical.
LL
LL
LL
LL
LL
post #220 of 417
Sorry to hear about your dad. Nice looking design though, can't wait to see loads of measurements. That should be lots of output for minimal dollars.
post #221 of 417
Thread Starter 
Quote:
Originally Posted by notnyt View Post
Sorry to hear about your dad. Nice looking design though, can't wait to see loads of measurements. That should be lots of output for minimal dollars.
~~ 35 a sheet for 3/4" Auraco ply x 10. Drivers. Screws and glue. A pair can be built for less than a grand including drivers. Not too expensive..

Tried to attach Sketchup, and a Rar of same - no luck. Attached the HR model.

 

wrckr51a.txt 0.4365234375k . file
post #222 of 417
My condolences about your father.

I have been anxiously looking forward to this build!! I am very glad you are getting to put saw to wood.
post #223 of 417
Quote:
Originally Posted by dB-Kicker View Post

My two cents on a couple things.

Here's a simplistic explanation of what a horn does: A correctly designed horn does two things. First it focuses the sound into a tighter beam. Second the compression chamber better matches the acoustic impedance of the diaphragm to the air around it (down to the cutoff frequency of the horn - where it begins to unload). BOTH things increase the load on the drivers diaphragm (thus requiring stronger motors to move the diaphragm a given distance - or more electrical energy to do the same) - and increase the SPL inside of the coverage pattern of the device.

To the first, a horn acts as a kind of a wave guide and does the same thing to the sound that a flashlight's reflector does - it directs and focuses the sound coming from the transducer. Let's say you have a light - that measures 10 foot-lambert's in open air at 1 meter, with the light radiating in every direction spherically 360 dgs around it (equivalent to an Anechoic environment). Now take that same light, and set it down on a perfect mirror (half space). At 1 meter distance, you'll read double the brightness or 200 foot lamberts (double free space). Add another wall and set the light at the juncture of the two walls - (quarter space) you double its output again (four times free space ). 400 foot lamberts. Add another wall to create a corner with a point and put the light down at the apex of that corner - (8 times the intensity of free space) 800 foot lamberts. And so on..

The tighter you focus that light the brighter that single light source is inside of its coverage pattern, but less area the light covers and the higher the intensity is in front of the beam. Similar to using a Mag Light and spreading the beam super wide vs. its tightest focal point. The tighter the acoustic beam - the larger the increase in SPL measured inside of its pattern.

The next thing a horn does is operate as an acoustic impedance transformer. Ordinarily - the radiation resistance of the driver is insignificant relative to the air it is pushing around (the air - a gaseous medium with quasi viscous properties) it is difficult for a little tiny cone to grab that air and control very well. Think of a Fan, or the impeller of a boat, or propeller to an airplane. As the fan blades spin, turbulent air peels off the outside edges and the blades efficacy is compromised. Same with an impeller or propeller. If you wrap a duct around those blades (any group of them) - the air or water cannot so easily shear and tumble off the edges - the now focused fluid or gas moves at a much higher velocity out the back side of the blades - while they turn at the same speed, though the load on the driving motor has increased. Decrease the size of the orifice the fluid/gas is exiting through (compress it), and again you increase the velocity of that medium on exit (and load on the drive unit)..

The duct has increased the mechanical impedance of the fan/impeller/propeller. To spin the same speed - because the device is moving more fluid / gas per sweep - the Load' on the driving motor is significantly increased. Decreasing the size of the ducts exhaust - also increases the impedance / load on the driving device and velocity of the exiting medium.

This is the same type of thing the compression chamber does in a Horn. It increases the acoustic impedance of the driving element - bringing it to a much closer match to the air around it. This increased grip on the air - improves the acoustic coupling of the diaphragm - and increase the SPL it generates for a given movement. While at the same time - increasing the force required to move the diaphragm a given distance.

This was most easily demonstrated to me one day - when I grabbed the huge exponential 400hz midrange horn at Klipsch and tried talking through it. My voice was Massively increased in SPL - but the force required to make said voice was incredible. It was physically hard for me to make a sound through the horn. Till that point - I couldn't fully comprehend exactly what it was that a horn does.

Two reasons bass horns can sound better than point source drivers:

1. The Spl increase brought about by the above lead to a significant reduction in distortion at a given SPL, provided the driving element has the strength to handle the increased load. The reason is simple - motors are one of the two components that generate distortion in a transducer - to quote Paul W. Klipsh's words to me directly If the cone Moves - the speaker Distorts, period. Increase its movement - increase its distortion. Anything you can do to reduce its travel for a given SPL will yield an immediate reduction in distortion components..

2. Dynamic Range. This is a distortion (dynamic compression) component RARELY talked about by the audio industry to the end consumer - and to me it is arguably the most important distortion component to address. Ever go to a fantastic concert - with exceptional sound - and drive home wishing you could have the dynamics of that system in your living room? Ever go to a HiFi store and hear a system that is purportedly ultra flat in f/r - but come away thinking the system sounded dull/lifeless/un-impressive? There is a Reason for that.

Something I have found in my own research into LF that may be almost counter intuitive to a consumer - but is true. The human ear responds more directly to increases in dynamic range - than to high Q deviations in frequency response. High dynamics will lend more of a sense of realism to sounds being reproduced than an uber flat on axis f/r, provided the object with the rough f/r follows the general trend of the flatter speaker.

The human ear is relatively insensitive to minor high Q deviations in amplitude - especially troughs, it roughly correlates to f/r smoothing of between 1/6'th and 1/3d octave (this is part of the reason most mfrs published material shows 1/3 oct smoothing).. If the highly dynamic systems 1/3 smoothed response is akin to that uber flat speakers response - a 20dB headroom system will sound tremendously more realistic than that Uber Flat 5dB or 10dB system. ( an XXdB headroom means the enumerated SPL capability broad band above the reference listening level. IOW if I choose 100dB for my reference level - my system will require 120dB broadband capability to be called a 20dB system.)

Regarding the time delay involved to propagate the signal from a Bass horn.
The speed of sound is 340m/s so to change it into yards the conversion rate of a meter to a yard is 1.0936133 so you would get 371.829 yrds/s and then you would use the conversion 3 ft=1 yard.
So sound travels 1115.486ft/s
So then you would use a basic physics equation of V=X/T
V=Velocity
X=Distance
T=Time
You're trying to find time so rearrange the equation T=X/V
T=3ft/1115.486ft/s
T=2.69 milliseconds

The length of this horn is approximately 6.096 meters - so a sound exiting the horn is delayed approximately 16.3982milliseconds. This does not account for the phase lead generated by the horns increased acoustic impedance match to air relative to a free air point source transducer at the corner frequency. In the 2 decades I've been studying and researching acoustics - including literally hundreds of AB and ABX test of various things, I've come to the conclusion - that regarding low frequency time delay - the human ear is as insensitive to errors in time as it is to the actual frequency.

Remember that at 4khz - an un damaged ear can hear 1dB spl - or literally molecules oscilating back and forth the distance of that molecules electron orbit (!) IOW colliding into each other. Correspondingly at those frequencies it is also the most sensitive to timing errors - between 1 and 4khz, the human ear can detect time errors as low as 2ms (1khz) and 1.4milliseconds at 4khz. 500hz the ear can detect 3.2ms deviations. At 20hz, it takes the average human ear over 70dB spl to cross the threshold of hearing. And at 16, about 100dB spl. Your ears are increasingly less sensitive as you drop (and increase) in frequency.

I subscribe to the theory my friend and a figure in our industry John Murphy does with regards to timing error's perceptibility at LF. Extrapolating Blauert and Law's threshold of detection for hearing timing error's to cycles at a given frequency - (their data covers 500hz/1khz/2khz/4khz and 8khz) it looks like we become sensitive to changes in timing of around 1 full cycle under the most controlled listening environment and using the most challenging material (clicks and pops).

Here is John's opinion on the audibility of delay in the bass range. My" current opinion would go something like this: "One cycle or so of delay in the bass range is probably just audible under controlled listening conditions (headphones) and with the most challenging program material (clicks and pops). Under less well controlled listening conditions and with less difficult program material the audibility thresholds are somewhat higher."

So - let's look at 10hz, 20hz, and 40hz (the range my sub will be used under.. even though Lil-Mike has pulled out the almost impossible and designed an almost 3 octave tapped bass horn in theHouseWrecker!) and see how long one cycle is.

1 period at 10hz is 113 feet. (!!!) Expressed in milliseconds - that would be analogous to 101 milliseconds (!!!)

1 period at 20hz is 56.5 feet. (!!) Expressed in milliseconds - that would be analogous to 50.6 milliseconds (!!)

1 period at 40hz is 28.25 feet. (!) Expressed in milliseconds - that would be analogous to 25.3 milliseconds (!)

Keep in mind - these models use an infinitely ridged wall for the horn - the actual deviations will be smoothed. My experience also tells me (from ABX testing) that Most Consumers under normal listening conditions cannot tell there is a significant timing error with as much as 3 times those numbers below ~~ 60/80hz. So.. looking at theHouseWrecker's model we have

101ms delay at 11hz. (Just under what the potential barely detectable threshold of a trained ear under controlled conditions and with program material specifically designed to highlight timing errors.) My experience is that the human ear can't detect even 4x that much delay at this frequency - it is very insensitive to this deep LF.

22ms delay at 20hz. Less than half of the best possible threshold.

23ms at 40. Right under the best likely potential threshold for detection.

I can use double those numbers and be quite happy.

Regarding distortion increasing as the line length increases":100% False. Increase the compression to a degree the velocity is so high at the reproduced levels in the throat - distortion will increase. Use too small a mouth, or folded turns with tight restrictions in the high velocity area (end of line), distortion will increase. Etc..

The designs Lil-Mike and I work up have a TON of energy put into them to reduce the acoustic reactance as much as possible, and match the load to the transducers being used. (for instance theHouseWrecker has significantly less acoustic reactance than the DTS10. It presents a very easy load to the driver face) - and ensure adequate expansion and mouth size relative to the driving element and expected F/R and SPL to be reproduced.

WOW....totally awesome post db, thanks for taking the time

Sorry about your dad
post #224 of 417
Nice fold. Those are going to be some big boys. 33 cubes.
post #225 of 417
I'll put together a ZIP with the cutlist and all the sketchup files later today if I have the time. This one is not small - pretty much designed to fit the space dB's got available and get all we can out of the CVX 15.

For those considering playing along at home, I am working on the "lil wrecker" that is a little more "EZ-take-home" sized. It is currently just over 27 cubes, but only gives up a Hz or two and a dB or two. Will fit through doors and around corners without too much trouble. Still needs wheels or a helper to move though.
post #226 of 417
Condolences on your father's passing.

5 sheets of 3/4" for each? Wow, yeah, those are gonna be some heavy suckers!
post #227 of 417
Looking forward to this. Also looking forward to the "Lil Wrecker." Can't wait to see what Lilmike's got up his sleeve...
post #228 of 417
And now I have even more reasons to buy a CVX. Thanks.
post #229 of 417
Thread Starter 
Quote:
Originally Posted by chrapladm View Post

And now I have even more reasons to buy a CVX. Thanks.

Glad to be of assistance and yes by all means - buy lots!

Attaching some shot's of set up to cut, the wood, and dry lay-up of Wrecker #1.

Photo

#1 is the Eurekazone RipSizer set up with an inexpensive Hitachi. End result - 30 seconds a rip - rips 100% repeatable to within less than 1/32'nd of an inch over 8'.

#2 is the Eurekazone track saw base set up for a cross cut, insanely quick rips and crosscuts - as accurate as your eye can make them.

#3 is the panels - bout half way through cutting them. Total time to cut 10 sheets into two Wrecker kits - about 2 hours.

#4 is initial dry layup of the compresion chamber - looking through the first expansion.

#5 is the same from the lower quarter view showing the exits of the of the second expansion.
LL
LL
LL
LL
LL
post #230 of 417
That Eurekazone tracksaw is something I NEED......

JSS
post #231 of 417
Thread Starter 
Quote:
Originally Posted by maxmercy View Post

That Eurekazone tracksaw is something I NEED......

JSS

Anybody who cut's full sheets of anything NEED's a killer tracksaw - the EurekaZone is absolutely awesome. I hold Lil-Mike responsible, he turned me on to them. (he did more than that - helped me place my order, since I had NO clue what I was getting.)

#1 bottom and top view of compression chamber

#2 Top view os same - with the additional panels making the last expansion.

#3 Showing woofer where it's final resting place will be

#4 Starting to dry-fit the box panels

#5 same as 4
LL
LL
LL
LL
LL
post #232 of 417
Thread Starter 
#1 driver hole and compresion chamber end

#2 looking at horn mouth. You can see the old Wrecker sitting out to pasture as a shelf in this one...

#3 closer

#4 up into mouth

#5 Lil-tyke for scale..

Excuse the driver cutouts - didn't have a wrench to tighten the routher bit - used an old jig saw given to me as a gift by a good friend... It didn't want to cut a round hole...
LL
LL
LL
LL
LL
post #233 of 417
Here are the sketchup files I sent dB, as well as the cutlists I prepared.

Bracing is not included, and is not at all optional on this one.

We're also still debating the need for an access panel.

 

v5.1a Sketchup.zip 136.826171875k . file

 

Cutlists.zip 12.8466796875k . file
post #234 of 417
If you wanted to stand one on end and fire at the ceiling, what effect would you have by moving the mouth of the horn to the small side?
post #235 of 417
Man,

Terrific design, Mike. Can't wait to see measurements!

JSS
post #236 of 417
Doesn't really look like you will need an access panel. Should be able to get at the driver and wiring enough to get it out through the mouth right? The back screws on the driver might be a PITA though. Maybe use some allen head screws similar to the ones TC Sounds uses so you don't have to worry about stripping the screw heads out.
post #237 of 417
is there a piece missing?

see red arrow in pic.
LL
post #238 of 417
Thread Starter 
Quote:
Originally Posted by LTD02 View Post

is there a piece missing?

see red arrow in pic.

no. They are not assembled. That was a dry lay up as mentioned above, just to make sure 100% of all my dimensions and cuts were accurate - and check to see if I had any warpage I need to correct for before I do final assembly.

That piece, as well as the block inside the bottom of the compression chamber are sitting on the pallet - waiting for me to hit the house tonight with more PL-premium, screws, paint, etc..
post #239 of 417
cool.
post #240 of 417
Just curios, since the initial plan has now become 2 enclosures, how do you think one will compare to one DTS 10?
New Posts  All Forums:Forum Nav:
  Return Home
  Back to Forum: DIY Speakers and Subs
AVS › AVS Forum › Audio › DIY Speakers and Subs › the HouseWrecker. 11hz Twin CVX-15 Tapped Horn