Curiosity here. What draws your attention and what helps you decide?

Whether the voice coil is silver or copper.

Just kidding.....

Would it help if it was titanium? No way you could blow that up.

Ok, seriously then. Right now, the Tumult looks pretty nice. :drool: Have to see what all is available though.

[This message has been edited by JT Clark (edited May 26, 2004).]

I absolutely hate the way titanium sounds.

funny you bring this topic up elsewhere...

I know darn well I'm not fooling anyone. I won't pretend our exchange didn't partially influence this. I would have started something similar soon anyway.

soundhound, did you have that entire pitcher of margaritas yourself last night? lol I wasn't aware that the voice coil actually emits the sound.

[This message has been edited by JT Clark (edited May 27, 2004).]

How about efficiency and Xmax number on the driver?

Speaking of Xmax, you’d need a yard stick to measure Tumult’s.
If anyone knows a subwoofer driver with that much Xmax distance, please let me know. I’d like to look into it.

Exactly. How much fun would it be to say that your sub displaces more air than your car engine? lol Resonant Engineering is supposed to be making a sub that has 47 mm of Xmax. But that's for cars. I don't know how well it will work for HT. Car subs have to factor in the transfer function of the car in their design. We'll see though.

Xmax is great to look at. Lots of linear response means lots of fun. Especially with a big cone to have massive displacement. Efficiency is alright. The efficiency of the enclosure would be better than that of the driver. Is that what you're saying?

How did you know about that pitcher or Margaritas????

Silver voice coils emit sound, copper ones do not.

On a more serious note.......

One of the tradeoffs of efficiency is enclosure size. Also, woofers that must move great distances forward and back by necessity have very long voice coils - they need this length so that the voice coil does not exit the magnetic gap at any point in it's forward or rearward journey.

The downside of this type of design is inefficiency. This is because of the fact that at any given moment, a good portion of the voice coil is not in the magnetic gap, and therefore is not contributing to the driving of the cone - it is just disapating heat. There are practical limits on how deep the magnetic gap can be to accommodate a longer voice coil. The longer magnetic gaps require correspondingly larger magnets in order to maintain a reasonably high magnetic flux density.

More efficient woofers and subwoofers have shorter voice coils that are completely or mostly contained within the magnetic gap, therefore almost all of the voice coil is instrumental in driving the cone at any given moment. The magnetic gaps are short and the magnetic field is very focused in that small area.

Both approaches are equally good, but one is just more efficient than the other and of course would need less amplifier power. With digital amplifiers that can generate large amounts of power, this amplifier issue is not such a big deal.

The subs that are used in professional applications tend to be of the more efficient type, and are used in large boxes - this generates large output at the cost of a large enclosure.

Inefficient woofers like the Tumult are designed for smaller enclosures that are more acceptable for home environments. To make up for the smaller enclosure (and the smaller piston size - 12" verses 18" for example), these woofers have large front to back excursion capability to move more air.

You either have a large cone with less excursion capability in a large enclosure, or a smaller cone capable of very large excursions in a smaller enclosure.

[This message has been edited by soundhound (edited May 27, 2004).]

Because I have almost no experience in this, I thought I would ask:

Aren't the large excursion, cube-type subwoofers better at aiding in the preparation of drinks that are "shaken, not stirred?"






[This message has been edited by bestbang4thebuck (edited May 27, 2004).]

Yes they are. They are also useful in frightening the crap out of your cat.

I like the large cone with the large excursion.

There is a relationship between small box size, frequency extension and efficiency where you can not have all three. Simplified version of what SH said. I'll see if I can dig up an old thread somewhere else over the weekend that had some very good info that might add to what SH said. 1/2 day Fridays! woot!

[This message has been edited by JT Clark (edited May 27, 2004).]

You can have two of these parameters, but not all three at the same time: small box size, frequency extension, and efficiency.

I sacrificed on the "small box size" aspect.

[This message has been edited by soundhound (edited May 27, 2004).]

so if i am looking at the tumult correctly it has 1.339in xmax which i would say is excursion? if that is the case, there are subs with greater excursions.

They state "one way", so the total excursion could be twice that amount if that is the correct spec.

For comparison, the total front to back excursion of my 18" JBL professional sub drivers is only 1" maximum.

[This message has been edited by soundhound (edited May 27, 2004).]

Id say that an 18 is not a small cone, yet for ht they come packaged in a relatively small enclosure. Small considering size of driver in relation to minimal box i mean. However the 18 in the small enclosure does have to have a good amount of excursion as you have pointed out so eloquently.

yeah i saw that one-way, as well, strange to put it like that... makes me think that perhaps it travels farther out, than say back inward. then you have some companies that just say excursion as one number, not each way or oneway or total.... standardization people, man how nice it would be.

i would say that servo control is a factor that makes a good sub. from my manual:
"The accelerometer (closed-loop, i put this in since it just said it above the quote) continuously monitors cone motions, providing us with a feedback signal for the servo control circuitry. This high-gain system is designed to improve linearity and reduce distortion approximately 30 times. over conventional non-servo systems. While the input signal is being sent to the amplifier which powers the driver, a continuous signal representing cone motion is being sent to a comparator circuit. This circuit constantly adjusts for any deviation between the input signal and the subwoofer's output. This self regulation results in extreme control over cone movement, and very accurate low distortion sound."

Ironically below this paragraph they talk about the amplifier as extremely efficient Class D, and cool at 1250rms. that contradicts what sh said about them being so inefficient.

here are the specs for my hgsII-18 thx ultra2:
cabinet size (h/w/d): 23.5"x21.25"x18.5"
frequency response: 15Hz-120Hz +/- 3db
harmonic distortion: less than 0.5%
subsonic filter: 15Hz or 35Hz
High Pass Crossover: 80Hz or 100Hz (6dB/octave)
Low Pass Crossover: 40Hz-120Hz (12 dB/octave initial, 48 dB/octave ultimate)
Phase: 0deg/180deg
Amplifier: Class D, 1250 watts RMS, 3000 watts peak
Woofer - forward firing: 18" (15.2" piston diameter)
Magnet: 220 oz (13.7 lbs)
Magnet structure: 380 oz (24 lbs)
Voice coil: Tandem 3" push-pull
Inputs: Line-level, Balanced & speaker-level
Outputs: Line-level and speaker-level
Weight: 115 lbs (approx)

considering that (above) and their "ultra-efficient" amplifier, id say that that theory goes out the window.

Where is the sensitivity? Not the SPL that they can attain, but the SPL with 1 watt @ 1 meter.

i dont know any manufacturers that put stuff like that in their manuals... that link i posted in the other thread where you were tyring to nitpick, MAYBE would have it. its the one from hometheaterhifi.com... there are ample reviews of the hgsII18 and the newer DD18 (same electronics except for parametric eq), look for some and see if they have the info that you desire. if it interests you so much, look it up and let me know. was there anything like you speak of about the tumult? you know the one that you linked to and were drooling over?

i only posted the specs to say that the three conditions that sh and you stated could be met.

I've got a Tumult.. at the moment though I think it's underpowered (I'm using a 500 watt amp.. it really needs 1kw or so)

It's in a 24" cube (outside) and it sounds wonderful... When I first used this thing I noticed bass in all kinds of things that I hadn't heard / felt before... and noticed EVERY place in my house where things were loose (pictures, drywall).. I had it up a little too high at first, but now it's calibrated to be a little higher than the rest of my speakers...

It's actually a fast driver.. it integrates well with my Magnepan's (they're crossed at 60hz)

I picked it by reading lots of reviews and typing with some of the guys on Madisound's forum...

it only costs what $499? sounds like a good deal to me, well if you can get an amp and build an enclosure for it for a good price. how much would you say that you have put into it total? break it down for us too if you dont mind, i.e. driver, cabinet, amp, etc.

Cabinet size is debatable and relative I believe. No arguing with that frequency response as I believe the manufacturer specs to be reasonably accurate. That's 2/3 at most. No offense, but that does not prove the theory wrong. I don't have time to go scouring the other forums for that info. Maybe a little assist here? Besides, the amplifier has nothing to do with what we're talking about. It's about the driver and its enclosure.

[This message has been edited by JT Clark (edited May 27, 2004).]

Here's about what everything cost...

500 for the driver
300 for the amp - 500 watt Parts Express plate amp that's in it's own little box
and I think about 100$ or so for wood, little speaker spikes...

and the other costs could include things like air compressor and brad nailer, table saw.. huge clamps, etc...

but if you've got all the tools it's doable in a weekend...

I still haven't really "finished" it yet.. it's just raw MDF but it weighs so much I'd rather wait until the wife's pressure is enough to make me move it I think if I do move it I'll put casters on the back so I can just lift the front and wheel it around...

Actually my sub is a good example of Soundhound's theory...

small size: check
frequency extention: check
efficient: 89.1db @1 watt.. so, no

You can have two of these parameters, but not all three at the same time: small box size, frequency extension, and efficiency.

seems like to me that that was applied to the whole sub...

i wasnt getting at anything other than the cost of the completed product. jt, dont try to read too much into things, :-).

[This message has been edited by curegeorg (edited May 27, 2004).]

...I know someone is going to ask so..

I put the plate amp in a seperate enclosure because I put a lot of work into securing the box and making it rigid (the walls are 1" thick) and the plate amp is sealed by a cheap plastic tub... it just seemed like a waste to do that to my box And this way when I find a bigger amp that I want to use with the thing I can

[This message has been edited by Unferth (edited May 27, 2004).]

Oooh! this one! You can hook TWO of those subs up to it! 1200 watts each, stereo sound! Ok, I'll calm down.

Unferth, can you tell if there is a particular range where the sub begins to lack output or is it across the board? Because if it's on the low end then porting may be an option.

[This message has been edited by JT Clark (edited May 27, 2004).]

i doubt that thing is pratical in application for subs :-). i was talking to jt, about dont read too much into anything. i guess that wasnt clear, so i edited my previous post.

I'm not missing any output, I just know I'm close to the limit of the amp because the clipping light has a tendency to come on

edit: After recalibrating the sub now the only time it goes into soft clipping is durring huge explosions, the rock wall in the 2nd LOTR, platform explosion in one of those Star Wars movies...

I've purchased TrueRTA and I'm going to get a Behringer measurement mic and see how it does but I'm sure it goes very deep



[This message has been edited by Unferth (edited May 27, 2004).]

curegeorg, ok. Fixed mine too. What does "practical" have to do with anything?

I was speaking about driver efficiency, not amplifier efficiency. Class "D" amplifiers are extremely efficient. The driver it is powering is undoubtedly quite inefficient. It's not really an issue in a finished system since they can make the amplifier as powerful as needed. The efficiency issue only comes into play if you are designing a speaker from scratch and must spec an amplifier to drive it.

Unferth:
Finally, I get to hear from a Tumult owner. Congratulations on your choice of Adire Audio. I happen to be a fan of their drivers. I have a Shiva subwoofer built from ground up. It weighs about 150 lbs and I put 2 casters towards the rear which saves my back when relocating it (just lift the front and push or pull).

I’m surprised that yours clipped with 500 watt amp. How loud were you running it? My Shiva never clipped even when turned up to door shaking volume and its efficiency is at 87 db. I use 150 watt amp from Parts Express and the enclosure is 5 cu ft with 15 inch passive radiator.

Those of you with expertise on speaker design, does Vas number matter a lot for subwoofer drivers? Adire’s Tempest which is also a 15 inch driver, has half as much of Xmax distance but almost twice as much of Vas as Tumult does. What does this mean in terms of the potential of each driver?

Maybe someone else can add, but Vas is driver/suspension stiffness. Bigger Vas means bigger box. I think Vas has mostly to do with getting the proper size box and efficiency.

Clipping a 500 watt amp surprises me too. Is it hooked up right? That should be a LOT of bass for a HT.

Xmax is how far the driver can move before distortion becomes audible. That is because some part of the sub reaches a limit of control. It should be self explanatory as to why that is important. The BL (motor strength) vs x (position) curves look different too. Let's make sure the above stuff is understood and correct first though.

[This message has been edited by JT Clark (edited May 27, 2004).]

[This message has been edited by JT Clark (edited May 27, 2004).]

jt pointed this out to me already. i didnt realize you guys were talking about drivers only.

i think you guys are delving into too technical terms as to what makes a subwoofer a good one. the understanding of everything is nice, but how important it is matters most.

for diy, i think you can get a better sub than what unferth has for $900. not that his isnt nice or good or whatever, but 500wts rms is not enough for my tastes. components for subs are WAY overpriced though. i guess a lot of technology is proprietary though, and that is why it costs so much for someone to buy and why a lot of companies design parts in house.

i hope this market changes in the future, because i would like to have in wall subs when i get space for a nice theater room. its gonna be hard to part with the ones i have now, but i really like the idea of having it buried in the wall. id do four, one in each corner...

Sorry I was stuck on a plane and couldn't respond earlier

I'm running the voice coils in series so together it's 4 ohms (really 3.6)..

Anyway.. I'm home now and tomorrow I'll reverify the clipping with LOTR or something.. maybe I can get my wife to leave the house for a little bit

the highest I've had the gain of the amp has been about "4" of "10".. right now it's at about 2.5.. and at that time the sub trim on the 950 was set to 0 and the highest the volume would've been was around -13db

The amp also has an eq feature on it and I may have had it set a too low.. I had it at 18hz and adding a couple of db in a pretty wide band (the manual and the adjustment nob is a little vague on exactly what the settings do) so that probably had some to do with it

I'll post my findings tomorrow...

[This message has been edited by Unferth (edited May 28, 2004).]

Well I started the topic with no real direction to it. If someone wants to talk technical then we'll talk technical. Some of these things are precisely how you can tell a sub is good or not without even hearing it.

Good, big, small, better? All relative to your expectations. Not everyone has the same goals.

Unferth, did you mean wired in series? The Tumult is a dual 2 ohm sub. Or did you have some special version made? If you have it in parallel then you're running it at 1 ohm. The amp may be going into a protect mode which may be confused with clipping, even with the indicator light.

Yes series... I realized that mistake last night...

Alright.. just watched the exploding deeping wall a couple of times and played with settings on the sub amp.. if I use the crossover and add a couple of db at 18hz the clipping light will flicker when the wall explodes only... if I don't use the eq the clipping "warning" light comes on but doesn't actually clip..

this is with the 950 at -13db and the sub trim at -3 and the sub volume control at half...

the system is calibrated currently for 75 db

so.. 500 watts is probably right at the minimum of what I need for the box it's in

So.. now I'm off to watch T3 again

[This message has been edited by Unferth (edited May 28, 2004).]

oh, so you FEEL that the specs about xmax, and all that other stuff are important to seeing if a sub is good or not? i would say that linear excursion is pretty low on my list of qualities that make a sub LOOK like it would be good.

So you don't care at all about distortion?

tell me how linear excursion is directly related to distortion?

The more the excursion, the more the distortion. The better subs will have more control of themselves at the higher excursion. That is, they have a larger linear region. One way of looking at xmax is where the sub goes from linear to non-linear. Also known as where the distortion becomes audible. Hearing this exact point varies from person to person, but there is a generally accepted measurement that extrememly few may be able to detect it below.

IIRC, it's necessary to have 4 times the displacement to create a frequency an octave down. So bass, especially the bottom end, takes a lot of displacement.

There is some more, but I'm not sure if I can explain it without getting technical. If you keep popping specific questions, I may be able to avoid that. I'll explain what I can.

you are saying two different things here. excursion does not CAUSE distortion and really by itself does nothing negative at all to the sound, it is, as you said, at the point where the movement becomes non-linear that distortion occurs. one would argue that if there was no point (or so small as not to be detected) of non-linearity, you could have any amount of excursion that you wished. you could have an excursion of 1 foot and it could have as much distortion as 0.1 inches if it is controlled correctly.

the reason why subs need to have large excursions in the first place is to move more air, which is i guess what you were saying in that 2nd paragraph.

to say that more excursion means more distortion is not true, because while it could, if controlled properly it will not. good subs control the movement well, while others do not.

my post about something needed for a good sub was servo control. servo control (which i explained above) basically negates any artifical output of the sub and keeps the movement along a linear path so as to minimize distortion. that is obviously watered down, but as you can imagine it makes a big difference.

its good to read up and find out a lot of cool stuff, but make sure you know how to apply it and what it means.

.

Effectiveness varies. The higher grade subs can control themselves better at the higher excursion levels. That's part of what makes them better. The amount of distortion present at any given excursion will be different (slighty or very) for most every sub.

[This message has been edited by JT Clark (edited May 30, 2004).]

it is not surprising that m&k defends their claim that about why they dont use servos. im sure that velodyne knows what they are doing or they wouldnt waste their time putting it in there. their sub would still be awesome without servo control, and if they thought for one millisecond that it would negatively impact the sound it would not be in their subs.

i guess this could boil down to my theory is better than your theory, and we are sticking by our engineering...

i myself have used servo (type of logic as well as actual applications of mechanical devices) in several manufacturing applications and from my experience they only make a product better by analyzing and then feeding back info that is pertinent to making a better product. but of course this has nothing to do with sound quality...

you cannot argue with one fact, velodyne has extremely low distortion throughout the spectrum of audio it is playing back and at any play back level.

m&k is well respected as well though, i dont think as much so with subwoofer manufacturing, but they do make good products. for them to claim that their subs will be more musical than one with a servo integrated device is pretty arrogant, but naturally they are trying to sell expensive gear to the masses so they will always say their ideas are best.

i dont know what other companies use servo control in their subwoofers, but id be interested as to which ones do. also i know that several amp makers use negative feedback to overcome feedback pushed back by the speakers, and that their are advantages and disadvantages to that approach.

i would put my sub (18in) in competition with any other sub, and im sure it is well above any except for some one offs or ungodly ridiculous priced ones.

anyway, i know you are happy with your m&ks wayne, and i am with my velodynes. once there is a new top dog on the market i wouldnt think twice about giving another brand a shot, but to this day i have not found one from any other brand...

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This post has been brought to you by curegeorg, thanks for reading.

.

Wayne and curegeorg,

Yamaha uses servo control on many (if not all) of its subs.

I've used a Yamaha YST-SW/80 in my dining room in a three piece stereo configuration for years.

Within its design limits, and at all reasonable listening levels, its a great little inexpensive sub - as are others in the current product line.

I don't expect it to compete with my Velodynes or B&W subs, nor should I.

Jeff Mackwood

wayne im sure you forgot some companies that use m&k...

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This post has been brought to you by curegeorg, thanks for reading.

.

I don't think you'll be taking that thing anywhere without a forklift.

I recently finished a sub that some might find interesting:

2- Tumults

Opposite-firing, push/push, to reduce cabinet vibration.

Custom hourglass cylinder, 1/2" thick PVC shell.

1 1/4" thick solid, custom CNC machined Mic 6 aluminum baffles.

On board L/T circuit to flatten and extend frequency response.

Only 2 1/2 cubic feet net interior volume.

One 1,050 Watts into 2 ohms switching amplifier PER VOICE COIL (4,200 Watts total)

Adjustable system 'Q', from .45 to 1.2.

Variable phase, 12 position, in 15 degree increments, plus a 0/180 switch.

Gain, phase and Q controls on the front panel. RCA/XLR inputs and detachable power cord on the back panel.

Signal/clip/protect indicator LEDs.

Lighted front panel control knobs to indicate position from across the room, at a glance.

I've built 17 subs in the past 9 or so months and used 22 drivers from around the world. The Adire XBL2 motor, which is basically a multi-gap, underhung (Dan Wiggins told me he prefers 'inner hung') design, is definitely for real.

BTW, this is a dedicated, discrete LFE only sub. I have a similar 2X15, using custom made drivers for dedicated redirected bass that's optimized for integration with my sats, but it's only powered by 4-800 Watt amps.

Alrighty Bosso... so now the question is how many blocks away do you have to get before you stop feeling the bass from your subs?

...my mother in law thought an earthquake was starting from just my one Tumult..

Bosso, you got any pics? What kind of frequency response does that mad thing put out?

Last week, my neighbor across the street lost electrical power. He told me that he was headed over to my house to see if I had lost power also.

He said that he got 1/2 way down his driveway and felt the rumble, so he knew I hadn't lost power, turned around and went back home.

I was testing the system, playing chapter 9 from LOTR FOTR (the on-fire, big demon dude) at that particular moment, clocking 127 dB peaks from 12 feet in 3,200 cubic feet, no clipping, no bottoming.

That sort of thing is fun, once in a while, but I really designed the system for max flexibility and sound quality. I mostly listen to hi-rez MC audio at around 90 dB with 105ish dB peaks.

Since there are 3 proprietary features that are still under non-disclosure agreement and that would be instantly seen in pics, I can't post any...yet. I promise pics soon, 'cause you just gotta see these.

To answer the original question of this thread, I look for effortless, on-time, distortion-free low freq reproduction with PLENTY of headroom in a small footprint, extraordinary industrial design package.

Impossible to find in the current commercial offerings, so I designed and built my own.

It's been a BLAST...literally.

What would one of these beasts cost a person interested in having one built?(Assuming all the engineering hours are complete, the costs would go for labor & materials - I'll assume the CNC program is saved on a disc which could simply be reloaded and run?)

127 db? That has to be completely awesome in a room! How low does it reach? Are you able to give us an idea of the frequency response? I'm wondering partially because that box seems small for 2 sealed and the sealed doesn't extend as far down as an ideal ported. However, the responsiveness (transients) of the sub should be insane even with a small sealed (I think at least) box. Push/push, so both going out at the same time? Side-firing or front-rear?

Sorry if this invades the nondisclosure agreement. I understand perfectly if you can't answer a particular question.

“on-fire, big demon dude”
You mean Belrog? The demon that swings flame sword and whip? He was in chapter 9? I’ll have to see it again when I get home.
BTW, that demon has a pair of wings but didn’t bother to use it when he fell off from the bridge. Hmmm, I wonder what Peter Jackson was thinking…

Well Gandolf didn't have any wings and he jumped after him.

That's only chapter 9? I would have thought more like 19, or even 29.

yeah it seems nice. only $5k plus. i typically dont like two drivers in one cabinet, but im sure its great. be nice to hear it somewhere... it is at least good that they have seperate amps for each.


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This post has been brought to you by curegeorg, thanks for reading.

pvc is slightly corrosive, and altogether pretty sorry compared to other synthetics currently available. an interesting choice for whatever you were saying about using it.

why dont you hook this up and test it out for distortion, there are numerous computer programs that can do it for you...

i am further curious as to what you do with all of the subs that you build/have built? who doesnt enjoy bass, but i dont need any of my space anywhere littered with boxes (surely heavy ones) containing anything, much less ones that are big and hard to move.

so much success at building subwoofers, why not go into business? ill take 5, only if they are offered with a money back guarantee of course.

my last comment is this huge grin that is over my face (just stopped laughing).

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This post has been brought to you by curegeorg, thanks for reading.

one more thing, what size are the tumults? i cant seem to find it from their site... i mean 12s, 15s or what.

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This post has been brought to you by curegeorg, thanks for reading.

Tumults are 15" only.

Who's website did you go to?
It sure is there at Adire Audio. http://www.adireaudio.com/StockProducts/raw_drivers.htm

Well I just linked right to the sub. That info is all the way up at the top of the page.