or Connect
AVS › AVS Forum › Audio › Subwoofers, Bass, and Transducers › New Sub From Danley Sound Labs
New Posts  All Forums:Forum Nav:

New Sub From Danley Sound Labs - Page 8

post #211 of 433
Hi All

A few questions have come up as well as a need to explain how two small drivers can make a lot of low bass.
The mouth bubble is an unofficial term and an explanation of what a horn does is needed first.
One thing a horn does is provide what is like a transformer in the acoustic realm, it can (in a perfect world) load the driver with an acoustic load much larger than it would feel based on its radiating area. It is the increase in loading which allows a horn system to have a greater electro acoustic efficiency or as seen by the user, more sound per Watt of input.
This transformer effect also has a high pass filter effect set by the horn's rate of expansion. For example, if one wants a horn to work to 30Hz, the rate of expansion if its cross section must be at a rate that doubles about every 24 inches. If you make a horn that doubles its area every 12 inches, you have a 60Hz horn instead or if you want 15Hz, it must expand more slowly, doubling its area every 48 inches.
The Horn effect actually extends outside the enclosure to a varying degree.
For example, if one places the spud enclosure in a room corner with the outlet at the floor/wall/wall junction, it is easy to see that the familiar corner loading where floor and walls act like a horn in that the expansion is confined to one eighth space.
From where ever the outlet is, keeping the rate of expansion in mind, one can plot out what the confined area is immediately outside the horn is and what ever that rate of expansion is, that is the frequency above which the physical surroundings continue the horns actual acoustic path and length.
To the degree you are within this zone, you are experiencing the low end more like the pressure zone experience in an automobile as opposed to the radiated pressure in free space. Obviously, this is an analogy, the thing is you have a greater pressure here for free which like Bill Murray said Which is nice.
This allows the sound where you are to be louder for a given amount of LFE in the bedroom or kitchen above.

Drivers.
We don't use exotic drivers in any of our products, with a few exceptions, what is perceived as exotic is a marketing concept and not an engineering concept, we do use some made to spec drivers and variants of stock drivers but the way I see it, for the most part, you can't get anything that performs better than the drivers that are designed to perform in a market where many folks can and do measure things.
Anyway, I suspect many of you would be surprised how great a horn system can sound when you get rid of a lot of the problems, our SH-50 will reproduce a square wave and can do it over a wide frequency range (over a decade), spanning both crossover points, possible because the design has none of the phase shift or driver to driver interference normal in multi-way speakers.

What I do in the design process is look at what is available and try a few of the best bets in the computer model. The sort of nearly last resort is sending out driver spec's for a purpose built driver but sometimes that's the only solution.
The best designs resolve one acoustical problem or another and that is what given them there strength as it were. Like the Synergy horns are a way to combine the outputs of multiple drivers over multiple ranges and have then knit together seamlessly acoustically such that what is radiated is as if it were one source in time and space.

In the case of the Spud driver, these are simply a very beefy 8 inch woofer with the right parameters and the new driver is a beefier one which we found / tried just recently and it is around a hundred bucks each in OEM quantity and no I don't think we want to sell drivers.
You can't just plunk any driver in a Tapped horn however as explained below.

A pretty common reaction to our Tapped horns subwoofer is surprise in how much sound what ever driver and box size can produce.
The Tapped horn allows the horn to be made much smaller than a conventionally driven horn.
In a normal bass horn, if one makes it too small (like a more convenient size) one finds the response droops off and exhibits a series of peaks and dips which are caused by the acoustic loading changing as a function of frequency (from being too small physically relative to the wavelength produced).
The thing I would say is the breakthrough in the Tapped horn, is that if you can get all the various driver and horn parameters just right (something which one couldn't do by accident, these are much harder than any other type of enclosure and have to be designed by computer) then one has a nice flat response to a much lower frequency than the horn size would normally have allowed the normal way.
By driving the horn at two different points in exactly the right way with just the right driver parameters, one can arrange the geometry so that where the lowest peak would have been, only one face of the drivers feels the load which where the dip had been, now both sides of the driver feel the acoustic load. The result is a nice broad response where the internal reactance's have annulled leaving a nice broad band device.
It is more complicated to design than a normal horn but when the horn must be as small as possible, the effort can be well worth it.
In effect, it has a variable driver of sorts, who's properties change with frequency compensate for the opposite changes the horn passage presents.
If look at the size of the spud and look at Ivan's half space TEF measure of one box (on edge, the minimum external horn bubble), you can imagine this is impossibly small for a 20Hz bass horn doing it the old way.

It is not uncommon to find the effect of the Tapped horn adds 10dB in sensitivity to the driver relative to it as a direct radiator.
In this case, a convenient example, an increase in sensitivity of 10 dB is brought about by a significant increase in acoustic load and as one then expects, one finds that the driver excursion is reduced by about a factor of 3.3 for a given radiated SPL. Also the excursion limited SPL is raised by about 10 dB (again, relative to that driver as a direct radiator).


RMK, I am glad you bought a second unit, in the design of it I had assumed people would use two under or behind a couch.

Actually Ivan suggested the under couch part first (a location I hadn't thought of) and that lead to the flat shape. One of the hard parts is scaling what we do commercially down in size for the home. How much is enough, how much overkill is just enough?
The TH-50's and SH-96's look tiny on my computer screen or in a big room like the photo below but much less so in a living room.

Anyway, I think you will be pleased with a pair, there is hardly anything more gratifying than making a first time guest uncontrollably jump to there feet in genuine wide eyed terror at what to them was certainly a car crashing into the house.
Best,
Tom Danley
LL
post #212 of 433
Thanks for the information and picture Tom. Do you have a full resolution version of that photo?
post #213 of 433
Quote:
Originally Posted by RMK! View Post

As a wise man once said, the driver is merely a piston pushing air ...

The magic of the TH-SPUD is the Tapped Horn enclosure. We watched The Dark Night Bluray (BTW, great movie!) last night and it was yet another amazing bass experience. The whole time I'm thinking I don't need another one of these but the second one is scheduled to arrive on Thursday this week. Guess I'll just have to make due.

Hey RMK!, any chance you could throw an spl meter at your LP for some key DK scenes for us?!

I'm thinking of the computer gun on a rail in the bat lab (chp. 14?), the chase scene starting at the rocket-launcher the bat-mobile intercepts, and the hospital explosion.

I'm really close to unloading my pb13 ultra and going over to the Danley-side.

Thanks for all the input and experience--bass junkies like me are enjoying the vicarious fix!
post #214 of 433
Quote:
Originally Posted by allredp View Post

Hey RMK!, any chance you could throw an spl meter at your LP for some key DK scenes for us?!

I'm thinking of the computer gun on a rail in the bat lab (chp. 14?), the chase scene starting at the rocket-launcher the bat-mobile intercepts, and the hospital explosion.

I'm really close to unloading my pb13 ultra and going over to the Danley-side.

Thanks for all the input and experience--bass junkies like me are enjoying the vicarious fix!

I would encourage any and all to come on over to the Danley side, there's plenty of room in this end of the deep pool! I just played several sections of a Blu ray DK with my Panasonic DE2000-SH/TH50 setup and had to turn the subs down -10dB as I was modulating our three story house. There's a lot of interesting dialog on this and it reminded that while incredible low end is great, the full picture is really only found in truly great dynamic range. Once you hear a Synergy Horn's clarity and accuracy along with incomparable low end you won't go back!

Mike Hedden
Danley Sound Labs, Inc.
post #215 of 433
Thread Starter 
Quote:
Originally Posted by Tom Danley View Post

RMK, I am glad you bought a second unit, in the design of it I had assumed people would use two under or behind a couch.

Thank you for all the good information Tom. This sub leaves me at a loss for words ... BTW, great IMAX photo

I'm thinking of placing the pair along the front wall behind the main speakers. I was going to try both horizontal and vertical. Any thoughts?


Quote:
Originally Posted by allredp View Post

Hey RMK!, any chance you could throw an spl meter at your LP for some key DK scenes for us?!

I'm thinking of the computer gun on a rail in the bat lab (chp. 14?), the chase scene starting at the rocket-launcher the bat-mobile intercepts, and the hospital explosion.

I'm really close to unloading my pb13 ultra and going over to the Danley-side.

Thanks for all the input and experience--bass junkies like me are enjoying the vicarious fix!

Not sure of the value of an max SPL measurement @ LP in my room but I might have some time tomorrow.
post #216 of 433
recently, i got a few subs and put them frontstage between my mains - tremendous improvement in the soundstage...the combination of ear/skin feel will give you clue which direction the pressure waves are coming from.
post #217 of 433
I've got a couple of questions for Tom or anyone who might can answer.

Tom I've been reading about your subs for a while and I'm particularly interested in THSPUD for one main reason.

I have a really open floor plan where my LP is. It opens to a kitchen, a dining room, a foyer and a hallway off of the foyer. It is hard to get any significant SPLs from a sub unless they are big and used in combination.

Needless to say there are no corners to place a sub anywhere close to the LP. The closest corner is behind a door that opens to the patio. Can't put a sub there as the door will bang on it.

There is a 4 foot wide wall directly behind the sweet spot where I have my current sub that divides the kitchen and the dining room area. I have found this placement gives me the best bass reinforcement vs listening position. The sub I currently have, fires across the opening to the kitchen in to the corner I was talking about behind the door. It actually does a decent job.

I was interested in THSPUD because you say it is an ideal close proximity sub and I was thinking of placing it where I currently have my sub. Not only that, I was thinking of standing it up, saving me several inches of floor space lost to the current cube sub.

Do you think THSPUD would work in this location? If I were to do this would it be better to place the hatch closer to the floor or higher off the floor? No matter if it is up or down it would be facing directly to my sweet spot and the placement is only 3 feet away.
post #218 of 433
Quote:
Originally Posted by howellk View Post

I've got a couple of questions for Tom or anyone who might can answer.

Tom I've been reading about your subs for a while and I'm particularly interested in THSPUD for one main reason.

I have a really open floor plan where my LP is. It opens to a kitchen, a dining room, a foyer and a hallway off of the foyer. It is hard to get any significant SPLs from a sub unless they are big and used in combination.

Needless to say there are no corners to place a sub anywhere close to the LP. The closest corner is behind a door that opens to the patio. Can't put a sub there as the door will bang on it.

There is a 4 foot wide wall directly behind the sweet spot where I have my current sub that divides the kitchen and the dining room area. I have found this placement gives me the best bass reinforcement vs listening position. The sub I currently have, fires across the opening to the kitchen in to the corner I was talking about behind the door. It actually does a decent job.

I was interested in THSPUD because you say it is an ideal close proximity sub and I was thinking of placing it where I currently have my sub. Not only that, I was thinking of standing it up, saving me several inches of floor space lost to the current cube sub.

Do you think THSPUD would work in this location? If I were to do this would it be better to place the hatch closer to the floor or higher off the floor? No matter if it is up or down it would be facing directly to my sweet spot and the placement is only 3 feet away.

Your situation perfectly describes the problems of so many sub designs, i.e., their performance is predicated significantly on boundary loading, room gain, and hopefully fairly small spaces. It is why car audio is pretty easy, you're in the pressure zone. Take those same drivers and amplifiers out of the car and see how they sound in a 2000 seat auditorium!
While the room is always the limiting factor, our Tapped Horn designs work great in small rooms, big rooms, shoot even outdoors! (see Keith Yates pictures on our website). The IMAX project that Tom shows in the picture from a previous post uses only four TH50's to yeild huge output all the way down to 10Hz in a multi-story, multiply hundred seat room. I've got two TH50's in my house and had to turn the bass down on The Dark Knight due to structural concerns, and I am not kidding.
Short answer is, horns work and Tapped Horns work better than anything else I've heard. The THSPUD will work great in your room and I am confident partly due to the fact that I just listended to one in our demo room which is 80' x 50' x 12'.

Thanks,

Mike Hedden
Danley Sound Labs, Inc.
post #219 of 433
Quote:
Originally Posted by Mike Hedden View Post

Short answer is, horns work and Tapped Horns work better than anything else I've heard. The THSPUD will work great in your room and I am confident partly due to the fact that I just listended to one in our demo room which is 80' x 50' x 12'.

Thanks,

Mike Hedden
Danley Sound Labs, Inc.

Thanks for the quick reply Mike. This the first sub I've been excited about in a long time.

Saving up some pennies right now.
post #220 of 433
Quote:
Originally Posted by RMK! View Post

Not sure of the value of an max SPL measurement @ LP in my room but I might have some time tomorrow.

Hey RMK!

I'm not so much looking for "max" spl, per se; but just want to see if we're in the same ball-park spl-wise on scenes I recently experienced.

Don't worry, I'm not a spl shoot-out kind of guy. I've seen enough of those 100lb spl-bashing drivers and hate the "noise" they produce.

If it isn't too much trouble, just set your system to a level you normally enjoy a movie at (for me it is +78 on my pre/pro) and check out some of those key scenes from DK and see what the SPUD kicks out at your LP.

For e.g., at my level above, I'm getting between 107dB (machine gun in the lab) - 110dB (bat mobile intercept of the rocket-launcher in the chase).

As you personally know, my pb13u is certainly a capable sub; but, I'm itching for "more" sound quality, and hopefully quantity also.

Sorry to bother, but I'm truly captivated by the lure of this SPUD--it's design and performance have me dreaming...

Thanks a lot RMK!
post #221 of 433
@Tom and Mike : congratz for creating the THSPUD concept. I'm sure it will redefine the way Home user will employ his subwoofers.
Your products line really cought my attention .I am more into the studio world than the hifi world at the moment, and i have always believed in good engineering rather than in some hocus pocus magic cables
I am really interested in the SH50 /TH50 combo , and the SH96 cought my attention . I intend to build a room from scratch and after sending some mails to friends working in the pro audio world, i didn't get any feedback. None of them knew about your line .As a matter of fact, i just couldn't find any french rental company which provides your products. The installation market is lead by l'acoustics, nexo , bose and apg here. Do you know where in France or surrounding countries i could get a demo of your products?
post #222 of 433
Thread Starter 
Quote:
Originally Posted by allredp View Post

Hey RMK!

I'm not so much looking for "max" spl, per se; but just want to see if we're in the same ball-park spl-wise on scenes I recently experienced.

Don't worry, I'm not a spl shoot-out kind of guy. I've seen enough of those 100lb spl-bashing drivers and hate the "noise" they produce.

If it isn't too much trouble, just set your system to a level you normally enjoy a movie at (for me it is +78 on my pre/pro) and check out some of those key scenes from DK and see what the SPUD kicks out at your LP.

For e.g., at my level above, I'm getting between 107dB (machine gun in the lab) - 110dB (bat mobile intercept of the rocket-launcher in the chase).

As you personally know, my pb13u is certainly a capable sub; but, I'm itching for "more" sound quality, and hopefully quantity also.

Sorry to bother, but I'm truly captivated by the lure of this SPUD--it's design and performance have me dreaming...

Thanks a lot RMK!

OK, FWIW, I used the Batmobile- Armored car scene(s) as the test. My system is test tone calibrated to 75db (RS Meter) on my Integra SSP. I was listening @-7db level on the Integra. With the RS meter in fast mode I was seeing 110db peaks @ LP during the scene. It was plenty loud and there was a whole lot a shakin going on.
post #223 of 433
Quote:
Originally Posted by Tom Danley View Post

...The Horn effect actually extends outside the enclosure to a varying degree. For example, if one places the spud enclosure in a room corner with the outlet at the floor/wall/wall junction, it is easy to see that the familiar “corner loading” where floor and walls act like a horn in that the expansion is confined to one eighth space...one can plot out what the confined area is immediately outside the horn is and whatever that rate of expansion is, that is the frequency above which the physical surroundings continue the horn's actual acoustic path and length..

It is interesting that many people today still recommend placing subs in the middle of a wall or, astonishingly, in the middle of the room. Tom, you seem to echo the same advice (above) of Klipsch (JAES April 1959) and Salava (JAES May 1999) in terms of corner placement. Why, then, would you recommend putting your SPUD under a sofa? (I believe that I already have an answer, but I really would like to hear your thoughts). One of the revealed observations that the latter paper (Salava) states is that there is no compensation for poor listening position, i.e., if you put the sub in a corner and it doesn't sound loud enough, it's time to move your listening position, because no placement of a sub can compensate for bad room acoustics at those frequencies.

Quote:
Originally Posted by Tom Danley View Post

...A pretty common reaction to our Tapped horns subwoofer is surprise in how much sound what ever driver and box size can produce...The result is a nice broad response where the internal reactance’s have annulled leaving a nice broad band device.
It is more complicated to design than a normal horn but when the horn must be as small as possible, the effort can be well worth it.
In effect, it has a variable driver of sorts, who’s properties change with frequency compensate for the opposite changes the horn passage presents.
If look at the size of the spud and look at Ivan’s half space TEF measure of one box (on edge, the minimum external horn bubble), you can imagine this is impossibly small for a “20Hz bass horn” doing it the old way.

Tom, when you look at most other horn designs, their sensitivities are usually in the 105+ dB/1W-M range. Your SPUD, et al. seem to be in the 95-97 dB range. I assume that the tradeoff is size of the horn relative to conventional exponential horn sizes at those frequencies. What I am wondering is how much efficiency you actually trade in cancelling response peaks using the tapped horn design in order to get relatively flat SPL over the sub's operating range. Would it be better to compensate the design a little less and use EQ to flatten the response curve? How about distortion figures when using tapped horn cancellation techniques - is there a rise in higher modes due to the tapped horn approach? If so, is it significant?

Quote:
Originally Posted by Tom Danley View Post

...One of the hard parts is scaling what we do commercially down in size for the home. How much is enough, how much overkill is just enough?

You mention overkill. To me, using a horn-loaded sub at lower than design volumes results in much lower distortion, much greater effective dynamic range, and much lower "compression" (including voice coil heating) at high room volumes. In other words, it's good to use a horn-loaded speaker designed for larger venues as a hi-fi unit for home use. Is this your understanding?

Chris A.
post #224 of 433
One of the revealed observations that the latter paper (Salava) states is that there is no compensation for poor listening position, i.e., if you put the sub in a corner and it doesn't sound loud enough, it's time to move your listening position, because no placement of a sub can compensate for bad room acoustics at those frequencies.

Danley Sound Labs has just been awarded a massive project so I'm not sure
how much time Tom or any of us for that matter can spend on this topic at this time. But here are a couple of quick thoughts.
A huge upside to the SPUD is its ability to place the listener practically inside the horn thus negating much of the critical frequency/modal issues one encounters especially in small rooms.
With regards to your issue of horn sensitivity, sensitivity should always be referenced to frequency. Most horn designs that will fit through a standard door with a sensitivity of 105dB will only have that at frequencies from 100 Hz and higher and they are anything but flat in the subwoofer pass band of interest. One of our competitors in the pro audio world references a sub's sensitivity to 1200Hz! It's a high number but not even close to what we call subwoofer frequencies.
The Tapped Horn is the most significant improvement in subwoofer designs in decades and yeilds in a given cubic volume the lowest cutoff, highest sensitivity, the lowest distortion, and group delay of anything on the market.

Mike Hedden
Danley Sound Labs, Inc.
post #225 of 433
Quote:
Originally Posted by Mike Hedden View Post

One of the revealed observations that the latter paper (Salava) states is that there is no compensation for poor listening position, i.e., if you put the sub in a corner and it doesn't sound loud enough, it's time to move your listening position, because no placement of a sub can compensate for bad room acoustics at those frequencies.

Danley Sound Labs has just been awarded a massive project so I'm not sure
how much time Tom or any of us for that matter can spend on this topic at this time. But here are a couple of quick thoughts.
A huge upside to the SPUD is its ability to place the listener practically inside the horn thus negating much of the critical frequency/modal issues one encounters especially in small rooms.With regards to your issue of horn sensitivity, sensitivity should always be referenced to frequency. Most horn designs that will fit through a standard door with a sensitivity of 105dB will only have that at frequencies from 100 Hz and higher and they are anything but flat in the subwoofer pass band of interest. One of our competitors in the pro audio world references a sub's sensitivity to 1200Hz! It's a high number but not even close to what we call subwoofer frequencies.
The Tapped Horn is the most significant improvement in subwoofer designs in decades and yeilds in a given cubic volume the lowest cutoff, highest sensitivity, the lowest distortion, and group delay of anything on the market.

Mike Hedden
Danley Sound Labs, Inc.

is that the same as nearfield placement?
post #226 of 433
Quote:
Originally Posted by Mike Hedden View Post

With regards to your issue of horn sensitivity, sensitivity should always be referenced to frequency. Most horn designs that will fit through a standard door with a sensitivity of 105dB will only have that at frequencies from 100 Hz and higher and they are anything but flat in the subwoofer pass band of interest.

Actually, I was really interested in Tom's response to my questions above (since I was quoting him) but your response is noted as a separate point of clarification. I assume broad spectrum measurements for sensitivity (i.e., apply 2.83 V across the terminal inputs to the system using pink noise-with 6 db peaks- across the usable bandwidth of the speaker and measure the sensitivity at 1 meter away in full-space anechoic, not half-space). What I was asking was the effects of designing for a flat SPL spectrum and its effect on overall sensitivity, and the effects on distortion measurements (I assume that you guys have done those measurements, at least on the DTS-20?). I believe that I also asked more questions that are fairly specific. When Tom gets 5 minutes or so, I'd like to hear from him (it would thrill me a bit to hear from "the man" even if he is busy).

Chris A.
post #227 of 433
Quote:
Originally Posted by RMK! View Post

OK, FWIW, I used the Batmobile- Armored car scene(s) as the test. My system is test tone calibrated to 75db (RS Meter) on my Integra SSP. I was listening @-7db level on the Integra. With the RS meter in fast mode I was seeing 110db peaks @ LP during the scene. It was plenty loud and there was a whole lot a shakin going on.

Sweet! That's what I needed to know...

Thanks for humoring me.

BTW, I'm hearing from more than you that the Danley sound is "unique" and "fast" in a most impressive way.

I've got to get me one of these!
post #228 of 433
Quote:
Originally Posted by RMK! View Post

OK, FWIW, I used the Batmobile- Armored car scene(s) as the test. My system is test tone calibrated to 75db (RS Meter) on my Integra SSP. I was listening @-7db level on the Integra. With the RS meter in fast mode I was seeing 110db peaks @ LP during the scene. It was plenty loud and there was a whole lot a shakin going on.

Any issues with the woofers bottoming out if not high passed? Or is that reduced to due to nearfield placement?
post #229 of 433
Hi Cask05

You ask Why, then, would you recommend putting your SPUD under a sofa? (I believe that I already have an answer, but I really would like to hear your thoughts). One of the revealed observations that the latter paper (Salava) states is that there is no compensation for poor listening position

Well you'll be disappointed to find the idea for the Spud didn't arise from in depth room analysis, actually Ivan commented that since many people put the couch on a riser, that that might make a good location.
The flat shape allows a long path internally something required for a low cutoff and the nearfield proximity would make the measured response at the listening position nicer.
So far as corner loading, the loading like a horn only takes place when the expansion into the room approximates the same area and expansion as the horn mouth.
In real life it is hard to get horn loading with a practical size enclosure, the difference of area's and expansion rates at the end of the physical horn is usually too large.

Tom, when you look at most other horn designs, their sensitivities are usually in the 105+ dB/1W-M range. Your SPUD, et al. seem to be in the 95-97 dB range. I assume that the tradeoff is size of the horn relative to conventional exponential horn sizes at those frequencies. What I am wondering is how much efficiency you actually trade in cancelling response peaks using the tapped horn design in order to get relatively flat SPL over the sub's operating range. Would it be better to compensate the design a little less and use EQ to flatten the response curve? How about distortion figures when using tapped horn cancellation techniques - is there a rise in higher modes due to the tapped horn approach? If so, is it significant?

AS Mike points out, If you look at the measured response of a small horn like one lab sub (a conventional bass horn I designed as a diy project some years ago, which measures 45 X 45 X 22 ½ ins), you find they do not have flat response. Unless a bass horn is very large, it will not have flat response. In the case of the Lab sub, it takes size of these to reach 40% efficiency and have a nice response shape.
For one of those boxes though, the response is not flat, it is drooped off and has a prominent peak and dip, it is in the mid / upper 90's in the 20-40Hz range.

One spud occupies less volume, has a much flatter response a smaller mouth and has a low corner approaching an octave lower, representing the difficulty factor cubed.
You won't find many conventional horns with a 20Hz corner, on the ground, you still need a mouth about seven by seven feet square with a large horn behind it.
It is when you make the horn smaller than ideal that the Tapped horn comes into its own.
So far as EQ, it can be illusory. For example, take a sealed box system that is extended below it's Fs. One popular brand using this approach claims both a single digit cutoff and says the Fb is about 80Hz. Lets say the driver has a sensitivity of 90 dB 1W1M, this figure refers to the region above the low corner at 80Hz. Below 80Hz, the response falls off at -12dB per octave, by 20Hz the system is -24dB from the sensitivity above 80Hz and at 10Hz is -36dB from 90dB 1W1M.
To make the response flat to 10 Hz, requires +36dB of compensation.
Lets say you have a 800Watt amplifier, this can provide a signal +29dB over 1Watt at the onset of clipping.
This system has a power limited output of 119dB (ignoring power compression and excursion limits) above 80Hz.
At 40Hz, it has reached clipping 12dB earlier at 107dB, at 20Hz at 95dB and at 10Hz, at 83dB. At 20Hz, the amplifier is clipping while at 80Hz, its at 3-4Watts. At 10Hz, the amp is clipping with less than ¼ Watt drive at 80Hz.

The last two, at any distance would be below the threshold of audibility as well.
Bass extension via equalization does reduce size but gobbles up all your headroom while maximizing power compression and such power issues relative to basic extended response..
So far as higher order modes, while the horn is a transformer (as in woofer) it is too small acoustically to support HOM's. If you were to drive it full range, up high it would be producing them so you use a crossover and use it as a woofer..

You mention overkill. To me, using a horn-loaded sub at lower than design volumes results in much lower distortion, much greater effective dynamic range, and much lower "compression" (including voice coil heating) at high room volumes. In other words, it's good to use a horn-loaded speaker designed for larger venues as a hi-fi unit for home use. Is this your understanding?

Yes, this is or can be exactly the case. All the problems loudspeakers have, get worse with increasing level AND these problems increase at a rate faster than the level increases. There has never been a more truer example of headroom is your friend.
In our case, we make things, some of which are ridiculous in the home, for rooms much larger than a living room so that's what I meant about scaling down.

I assume broad spectrum measurements for sensitivity (i.e., apply 2.83 V across the terminal inputs to the system using pink noise-with 6 db peaks- across the usable bandwidth of the speaker and measure the sensitivity at 1 meter away in full-space anechoic, not half-space). What I was asking was the effects of designing for a flat SPL spectrum and its effect on overall sensitivity, and the effects on distortion measurements

We use a swept sine TDS (TEF) for most measurements and Easra is a new system Mike is trying out.
Because of the size of many of the subwoofers we make and that they are used in multiples, we can't measure at one meter, the cabinets take up too much of that volume within the one meter radius.
For that reason many subs are measured at 10 meters which minimizes the error.
For example;
http://www.danleysoundlabs.com/pdf/T...ec%20Sheet.PDF

In commercial sound, subwoofers are generally measured in half space and there aren't any anechoic chambers I know of that go down low enough other than the outdoors.
The outdoor 10 meter measurements take some preparation and time, not to mention a day when there is little or no wind, these are not done yet.
So far as distortion, that is too complicated a subject for a quick answer. What I can say is that in general it is electromechanical nonlinearity related to radiator motion.
So far as a the horn portion, it amplifies the fundamental and harmonics according to its frequency dependent gain, from that standpoint, as well as listening, it is desirable to have flat response..
Hope this helps,
Tom Danley
.
post #230 of 433
Quote:
Originally Posted by gpmbc View Post

Any issues with the woofers bottoming out if not high passed? Or is that reduced to due to nearfield placement?

ALL subs need to be high passed or the potential is there to "bottom out"-especially with movie clips.


When you drive any loudspeaker loud-below where it is tuned- it will start to overexcursion and possibly bottom out.

The key to ANY loudspeaker is to operate it within the designed pass band.
post #231 of 433
Quote:
Originally Posted by Cask05 View Post


Tom, when you look at most other horn designs, their sensitivities are usually in the 105+ dB/1W-M range. Your SPUD, et al. seem to be in the 95-97 dB range. I assume that the tradeoff is size of the horn relative to conventional exponential horn sizes at those frequencies. Chris A.

DO you have a link to any of those "other horn designs" that have a measured -3dB point below 20Hz? With published response graphs?

I am not aware of any. You will find that the high sensitivity horns have much higher cutoffs.

If you want to look at tapped horns that have a higher sensitivity, look at cabinets such as the TH115.

The Tapped horn, when used in the same freq range as other "equal" horns, holds it own very well-with equal or higher SPL and a much flatter response-especially down near low freq cutoff.

http://www.danleysoundlabs.com/tappe...MODEL=TH%20115

It is MUCH louder, does not go anywhere near as low as the TH SPUD.
post #232 of 433
Quote:
Originally Posted by Tom Danley View Post

...So far as corner loading, the loading like a horn only takes place when the expansion into the room approximates the same area and expansion as the horn mouth.
In real life it is hard to get horn loading with a practical size enclosure, the difference of area's and expansion rates at the end of the physical horn is usually too large.

I'm having a little trouble interpreting exactly what you are saying, but my take is that you are saying that "horn loading" (including the room's effect as a final fold of the horn...?) is only effective when the transition to the room's corner space transition is not too abrupt, i.e., the horn's mouth must transition somewhat smoothly into the room corner. I also am guessing that you are relating "horn loading" back to the throat of the horn and the driver. If I'm way off, then I will acknowledge that fact. If you are saying the the SPUD cannot take advantage of corner room loading due to it's small mouth relative to the corner, then I think that I understand that, however, I think that the corner room gain effect is still there.

I'm not a real fan of really near-field pressure zone effects, i.e., like sitting less than 1-2 meters from the horn's mouth. Excluding this effect, and assuming that some of us are wanting a more uniform and "ambient response" of the room (I could be beginning to split hairs here, but I doubt it), then my comment about room shape being the driving factor acoustically is what I was trying to highlight. Subwoofer headphones is not something that I'm interested in...

Quote:
Originally Posted by Tom Danley View Post

AS Mike points out, If you look at the measured response of a small horn like one lab sub (a conventional bass horn I designed as a diy project some years ago, which measures 45 X 45 X 22 ½ ins), you find they do not have flat response. Unless a bass horn is very large, it will not have flat response. In the case of the Lab sub, it takes size of these to reach 40% efficiency and have a nice response shape.
For one of those boxes though, the response is not flat, it is drooped off and has a prominent peak and dip, it is in the mid / upper 90's in the 20-40Hz range.

One spud occupies less volume, has a much flatter response a smaller mouth and has a low corner approaching an octave lower, representing the difficulty factor cubed.
You won't find many conventional horns with a 20Hz corner, on the ground, you still need a mouth about seven by seven feet square with a large horn behind it.
It is when you make the horn smaller than ideal that the Tapped horn comes into its own.

Okay, I would like to amplify this - I'm not yet an accolyte of tapped horns as of this writing, so I need a little leeway here. This last statement you make doesn't say much to me other than an assertion --I'm looking for some physics to tell me "why". I'm still wondering what the tradeoffs are (in addition to an obvious hit in efficiency) while using tapped horns over conventional horns. I still having trouble seeing that harmonics or other "nonlinearities" are not measurable at all in the tapped horn at higher drive levels. I know that these effects are minimized (wrt direct radiators) in an exponential (conventional) horn design, but not zero. I would think that tapped horns would suffer some sort of hit in this area over conventional horns - no?

Quote:
Originally Posted by Tom Danley View Post

So far as EQ, it can be illusory...

I believe that I was referring to the typical response peaks on a truncated horn, implying lower gain, not grossly boosted gain below the horn's Fc.

Quote:
Originally Posted by Tom Danley View Post

So far as higher order modes, while the horn is a transformer (as in woofer) it is too small acoustically to support HOM's. If you were to drive it full range, up high it would be producing them so you use a crossover and use it as a woofer..

I don't believe that I'm talking about driving it full range, to the contrary--I'm referring to the usable passband (~15--> ~60 Hz with the SPUD). My interest is in how much "non-source-related output" (whatever you want to call it - I call it distortion or higher harmonics - like 2nd and 3rd) is present in the SPUD as you increase the drive level, relative to a typical exponential corner horn design driving into the room below its Fc. This can be measured--no? Has it been measured for the DTS-20 or SPUD? I can provide other material to clarify what I'm talking about, if that would help.

BTW, I'm not trying to argue sensitivity measurements (I was only trying to define the term in some generic sense because the subject was amplified by Mr. Hedden), but rather I was trying to understand the effects of tapped horn "spectrum smoothing" design on resulting sensitivity and efficiency. I still don't believe I understand that at all, but I would like to understand it more.
post #233 of 433
Quote:
Originally Posted by Cask05 View Post

. This last statement you make doesn't say much to me other than an assertion --I'm looking for some physics to tell me "why". I'm still wondering what the tradeoffs are (in addition to an obvious hit in efficiency) while using tapped horns over conventional horns.

I am wondering about what "hit" in efficiency you are actually talking about?

Maybe this will help explain things a bit.


http://www.danleysoundlabs.com/pdf/danley_tapped.pdf
post #234 of 433
Quote:
Originally Posted by Ivan Beaver View Post

I am wondering about what "hit" in efficiency you are actually talking about?

Ivan, I appreciate your concerns with regard to answering my unusual questions. However, I think it best to respond directly back to Tom at this point, otherwise I think "Tower of Babel" effects might get out of hand (...that's a biblical term, for those who are uninitiated...).

However, to answer your question -- I'm always referencing a folded corner horn of exponential flare as a default (including the effects of room corner gain) if I fail to make the point explicitly. I own some of these, and it's very natural for me to make comparisons with respect to that configuration.

Chris A.
post #235 of 433
Thread Starter 
Quote:
Originally Posted by Cask05 View Post

I think "Tower of Babel" effects might get out of hand

A self descriptive phrase if ever there was one.
post #236 of 433
Thread Starter 
Quote:
Originally Posted by gpmbc View Post

Any issues with the woofers bottoming out if not high passed? Or is that reduced to due to nearfield placement?

I have a 15Hz high pass with 24db slope set via my Velo SMS-1. The THSPUD was more easily bottomed in the side wall location. It is now nearfield (or within the horn bubble) and does not "bottom" during bass heavy scenes played at my normal listening levels. Like all subs, it is position dependant to achieve the best results and in my limited experience, the SPUD performs best if near field.

I am going to try alternate locations when the second SPUD arrives
(tomorrow).
post #237 of 433
Quote:
Originally Posted by RMK! View Post

I have a 15Hz high pass with 24db slope set via my Velo SMS-1. The THSPUD was more easily bottomed in the side wall location. It is now nearfield (or within the horn bubble) and does not "bottom" during bass heavy scenes played at my normal listening levels. Like all subs, it is position dependant to achieve the best results and in my limited experience, the SPUD performs best if near field.

I am going to try alternate locations when the second SPUD arrives
(tomorrow).

so even with the 15Hz/24dB hi pass, it will still bottom out if you are not careful with the volume knob?
post #238 of 433
Thread Starter 
Quote:
Originally Posted by SlowcarIX View Post

so even with the 15Hz/24dB hi pass, it will still bottom out if you are not careful with the volume knob?

I wouldn't describe myself as "carefull with the volume knob"

As Ivan said the THSPUD and virtully any sub or subs can be over driven. In it's current location (i.e. subwoofer headphones) it does not bottom at my normal listening levels on bass intense material.
post #239 of 433
Quote:
Originally Posted by RMK! View Post

A self descriptive phrase if ever there was one.

Yeah, this seems to have gotten a bit esoteric.

So, we have established that the SPUD rocks, right?!

Now my scheming to get my hands on one continues...
post #240 of 433
Quote:
Originally Posted by RMK! View Post

I wouldn't describe myself as "carefull with the volume knob"

As Ivan said the THSPUD and virtully any sub or subs can be over driven. In it's current location (i.e. subwoofer headphones) it does not bottom at my normal listening levels on bass intense material.

i got a dts20 that does that and 2100 from here recommanded a sms-1 - just wondering how effective it will be...

do you think by truncating the 15Hz and below, you will loose what the producers intended to put in the soundtrack what was meant to be felt, eg shock waves from an explosion?
New Posts  All Forums:Forum Nav:
  Return Home
AVS › AVS Forum › Audio › Subwoofers, Bass, and Transducers › New Sub From Danley Sound Labs