JL Audio 13w7 in prowedge box

[mayhem13]

WmAx, what size enclosure do you propose and at what tune ? I can't seem to get a port(s) to work with this driver without either high port compression or port resonance in the freq range. Would the use of the DCX be used to control those issues as well? If you personally had a W7which system would you build and why?

[WmAx]

mayhem13 wrote:

WmAx, what size enclosure do you propose and at what tune ? I can't seem to get a port(s) to work with this driver without either high port compression or port resonance in the freq range. Would the use of the DCX be used to control those issues as well? If you personally had a W7which system would you build and why?

Personally? I would use two, in stereo, using the following cabinet specifications:

Volume=4.5 ft^3
Vent=W=12 / H=4.25 / L=63
Tuning=21Hz

As for slot design and bracing design, refer to avaserfi's Infinity Kappa Perfect VQ DIY subwoofer - after all - I specified that subwoofer cabinet design for his application.

Assuming for some minimum level of thermal compression, port compression and non-linearity, at 1M Free Field / 2M Ground Plane, as done in Ilkka's tests, one could expect over 100dB output at 15hz, over 110dB at 20Hz and over 115dB output over 30Hz. In reality, it may produce higher output than this; I am being very conservative. In a room, one can expect at very minimum, a flat 6dB boost across the range. In reality, +10db is commonly gained across much of the band.

If I was worried about over-excursion under tuning, which is not much to worry about really, considering power handling at 10Hz is still several hundred watts, I can add a 2nd order high pass Butterworth filter at 20Hz and no over-excursion will occur at any point.

This will yield a first port resonance of 107Hz. Assuming you cross over no higher than 80Hz with a 4th order L-R crossover transfer function, then there is no good reason to believe that port resonance will be an issue in application. I can add an additional notch at 107Hz if I am overly worried about it.

A DCX2496 would be used to add all xovers/filters discussed here in.

-Chris

[mayhem13]

Thanks, it would be asking alot of that sub to play above 80hz anyway. 4.5cu gives more than enough room for a slot port and designed well would add to bracing. Well done. Me personally, I'd just route the holes for the PR's on the side and tune with weight. I'm lazy that way-cutting all that wood and measuring for the slot is a major pain in the $%@*&. As to Xmax, i couldn't achieve it in either alignment up to 3kw until 10hz !!! Have you done any PR designs. If so i'd like to get your opinion of SQ and efficiency on them.

[Ricci]

WmAx wrote:

Your point is lost, in that in the ported system example proposed, it would have higher output at LF, as compared to any other commercial subwoofer, excepting the servo motor fan bladed based thing of which I forget the name.

No it won't. Where is your proof of this and exactly what are you considering LF's? 25hz? I can think of at-least 4 units that would have higher out-put anywhere below 80hz.

Of what is this low confidence based upon? The signal will be greatly attenuated by the time port resonance frequency is encountered. And yet, people ignore the port resonances that are located in the used passband, with no attenuation, in most ported full range hi-fi speakers.

Yes, and you can clearly see the effects of those in many loudspeaker measurements. They can also be audible. Greatly attenuated by the crossover? I don't think so. It's not even an octave away from 80hz. Again what if you need to cross over at 100hz? You are going to be very lucky to have 12db's of attenuation at 107 with an 80hz crossover. Still could be quite audible.

A 6" port is not sufficient; the result will be substantial port compression at high output levels. Even the 3.25" x 12" port would still be sub-optimal. The 4.25" x 12" port I specified is not even perfect - but it was chosen with the point of keeping the port resonance just high enough that it would not be an issue, when using a 4th order xover at 80Hz(common upper range point used by most people). If you want a real world example using a similar diameter driver with high output capability, note the SVS PBULTRA 13 measurements by Ilkka. Around the vicinity of port tuning, output is nearly halved(5dB) on the maximum SPL trace, using a port cross sectional total area that is more than that of a single 6" port.

-Chris

Yes, I'm quite aware of all of this. That's why most of us are suggesting PR's or sealed. A 6" port would not be ideal, but it wouldn't be a major issue until very high output levels. This is a very hard driver to port correctly. Many people are using a single 6" port with 15's that move just as much air as a 13w7. The SVS uses almost exactly the same port area as a 6" port. Not more. It is 3 3.5" ports.

The box that you are suggesting is not a bad alignment, but it takes nearly 2500watts to get all of the out put from it and I'm not sure that the 13w7 will take that much power thermally when it is at the minimum motion point near tuning. The slot port is going to take up nearly 2 cu ft of enclosure volume, so your enclosure is really about 6.5ft also. I just would like to see a lower tuning to get more output down low 14-18hz if he's going to port or PR it.

[Warmon]

WmAx wrote:

How is it more suited to a sealed application?

Because of the combined electrical and mechanical dampening properties in comparison to the free air resonance. It's a textbook case: Qts > .40, EBP < 50.

[WmAx]

Warmon wrote:

Because of the combined electrical and mechanical dampening properties in comparison to the free air resonance. It's a textbook case: Qts > .40, EBP < 50.

Efficiency Bandwidth Product is a rule of thumb, especially when the EPB is do close to the margin. If it was extremely skewed to one or the other, then it is indicative. But this is not the case. To really find out, a thorough examination of modeled behavior needs to be done -- which I have - and the driver will perform superior in all relevant aspect when used in a properly ported/PR cabinet system.

-Chris

[WmAx]

DS-21 wrote:

If you want to take that line, forget the vented box. That is is an utter waste of the driver's capabilities.

To get the most bass out of any given driver, the best solution is almost always a bandpass variant. (That's all Dr. Geddes uses, for instance.) After bandpass comes vented, and after vented comes sealed, after sealed comes cardoid, and after cardoid comes dipole.

The problem with bandpass is that to get substantial gain vs. what a ported enclosure will produce, you have to significantly narrow the bandwidth of operation where that gain occurs. Using a bandpass across a wide band, with a relatively smooth response, it has virtually no practical advantage over a ported alignment.

You guys keep assuming that SPL at LF is the only goal for most subwoofers. For some people, that's true. However, many of us also have aesthetic considerations. A ported/PR subwoofer is generally not only larger, but also less flexible in terms of enclosure shape than a sealed box.

The only issue I am discussing is practical maximum performance conditions for hi-fi audio use.

To the OP, my honest advice would be to sell the 13W7 and buy a better driver. I've never heard a W7 used in the car or home to sound right, and for that matter I can't say I care for the Fathom, either. The reason is probably the giant compromise JL made to get the long stroke and admirably linear BL: the inductance of the driver is through the roof!

Your subjective listening assessment is as valid as any other non-controlled listening experience - that is - it is of low credibility. In contrast to your statement, many hi-fi reviewers, with their uncontrolled subjective listening assessments, seem to think it's one of the best subs that they have used, regardless of the inductance. In all, the only thing that inductance really affects here is the high frequency response of the driver - which when used as a sub-woofer in the typical <100Hz band - is a non-issue.

-Chris

[WmAx]

Ricci wrote:

Yes, I'm quite aware of all of this. That's why most of us are suggesting PR's or sealed. A 6" port would not be ideal, but it wouldn't be a major issue until very high output levels. This is a very hard driver to port correctly. Many people are using a single 6" port with 15's that move just as much air as a 13w7. The SVS uses almost exactly the same port area as a 6" port. Not more. It is 3 3.5" ports.

And the LF output of that SVS unit has about a 50 percent output reduction near maximum output levels around the tuning frequency due to port compression.

The box that you are suggesting is not a bad alignment, but it takes nearly 2500watts to get all of the out put from it and I'm not sure that the 13w7 will take that much power thermally when it is at the minimum motion point near tuning. The slot port is going to take up nearly 2 cu ft of enclosure volume, so your enclosure is really about 6.5ft also. I just would like to see a lower tuning to get more output down low 14-18hz if he's going to port or PR it.

I modeled the driver with 1000 watts. It produces extremely high output levels across a very wide band, and this was with substantial de-rating I assumed, to account for thermal and other non-linear behavior(s). The real key to performance here is the port - a properly designed port with larger than standard cross section allows for a substantially higher LF output ability.

No it won't. Where is your proof of this and exactly what are you considering LF's? 25hz? I can think of at-least 4 units that would have higher out-put anywhere below 80hz.

What commercial product examples would these be? Perhaps some subwoofers with multiples of drivers(the only case where I can think of this possibly occurring, considering the currently available products of which I am aware of)? I need some form of evidence - 3rd party tests like Ilkka's or the other site that does similar measurements would suffice.

Yes, and you can clearly see the effects of those in many loudspeaker measurements. They can also be audible. Greatly attenuated by the crossover? I don't think so. It's not even an octave away from 80hz. Again what if you need to cross over at 100hz? You are going to be very lucky to have 12db's of attenuation at 107 with an 80hz crossover. Still could be quite audible.

You are correct, that the output will -12dB, I made an error in that regard. It is still not an issue that I can see will be of any consequence - as this frequency - which is substantially clear of the xover range - can be cascade filtered and/or notched, IF YOU ARE WORRIED about it. Pretty much no one seems to care when the port resonance resides in the 200-500hz range(extremely common) on most vented high-fi speakers of high regard. I contend, that I prefer there to be no such chance, and I do provide for ways to make this a non issue in the subwoofer design I presented.

-Chris

[WmAx]

mayhem13 wrote:

Thanks, it would be asking alot of that sub to play above 80hz anyway. 4.5cu gives more than enough room for a slot port and designed well would add to bracing. Well done. Me personally, I'd just route the holes for the PR's on the side and tune with weight. I'm lazy that way-cutting all that wood and measuring for the slot is a major pain in the $%@*&. As to Xmax, i couldn't achieve it in either alignment up to 3kw until 10hz !!! Have you done any PR designs. If so i'd like to get your opinion of SQ and efficiency on them.

I have used PR. I can not offer subjective opinions, if that is what you want, as my subjective opinions are worthless, as they would be under non-controlled sighted conditions, along with other bias factors. But, functionally(and measurably), it is virtually identical to a properly designed ported system(which are pretty rare, it seems). I prefer the slot port system only due to cost. By the time you buy a very high quality driver or two - the added cost for the required number, size and quality of PRs to not limit output, often add several hundred of dollars to the budget, where as the slot vent system can be done with the added cost of a little more building material.

-Chris

[thxgoon]

I think we are all getting a little off topic with the ported vs PR vs sealed debate. Remember that the OP already has the driver and is considering a pre-made box. To summarize:

1 - Ported. Properly designed you'll get up to 6db of addotional output near the tuning frequency which would result in deeper response, less power needed and lower distortion, though if tuned much above 17hz group delay can enter the audible realm. The box will be more challenging to design and build but there are plenty of people on this site to help with this and a notch filter may be needed.

2. Passive Radiator - Everything above applies though you won't have to worry about a notch filter, port compression or chuffing. You will need to purchase a radiator or two to get the best performance.

3. Sealed. The simplest design. All of the above issues become a moot point at the expense of 6 db of output down low. According to a model earlier this would still result in 114db at 20hz anachoic and last I checked this is pretty awesome.

So there you have it. If you want tremendous output and don't mind putting in a little extra work, ported or PR are good solutions. If this is your first build and want a simple design, go sealed.

tpaxadpom - I looked at the pro wedge you were considering. The box looks awefully small to me for a home theater application. With smaller volume you increase the system Q value which leads to extremely high trasient response at the expense of extension and efficiency. I think you'd find it to be a bit boomy. Anyone have acces to WinISD to run some quick numbers for a sealed enclosure for .707? If you don't mind building your own the MDF can be had for less than the cost of the Pro Wedge and would yield better results IMHO. Let us know what you're thinking.

[WmAx]

thxgoon wrote:

though if tuned much above 17hz group delay can enter the audible realm

Please refer me to the perceptual research, that meets proper scientific protocols, that shows significant audibility. In lack of specific research that I could find, I have produced careful simulations, and used ABX methodology on myself and several others. The conclusion being, the group delay introduced by a normal ported design target function is not of any audible significance.

3. Sealed. The simplest design. All of the above issues become a moot point at the expense of 6 db of output down low. According to a model earlier this would still result in 114db at 20hz anachoic and last I checked this is pretty awesome.

Under what conditions can one achieve 114db at 1M free field/2M ground plane, around 20Hz, using the JLW7 in a sealed configuration? The Fathom 13" unit is an excellent example - and it can not approach this SPL at that frequency. Nor do my sealed models agree that such a SPL is probable.

tpaxadpom - I looked at the pro wedge you were considering. The box looks awfully small to me for a home theater application. With smaller volume you increase the system Q value which leads to extremely high transient response at the expense of extension and efficiency. I think you'd find it to be a bit boomy.

You could use parametric equalization to counter the small enclosure response - and remove the peak due to high QTC.

Anyone have access to WinISD to run some quick numbers for a sealed enclosure for .707? If you don't mind building your own the MDF can be had for less than the cost of the Pro Wedge and would yield better results IMHO. Let us know what you're thinking.

For a QTC of 0.707, a volume of approximately 4.1 ft^3 would be required.

-Chris

[thxgoon]

WmAx wrote:

Under what conditions can one achieve 114db at 1M free field/2M ground plane, around 20Hz, using the JLW7 in a sealed configuration? The Fathom 13" unit is an excellent example - and it can not approach this SPL at that frequency. Nor do my sealed models agree that such a SPL is probable.

This was based on a previous post where a PR design was reported to have 120db output at 20hz. I thought it sounded a bit extreme as well but I have no personal experience with this driver and have not had a chance to model it.

You could use parametric equalization to counter the small enclosure response - and remove the peak due to high QTC.

For a QTC of 0.707, a volume of approximately 4.1 ft^3 would be required.

There's 2 great ideas for a sealed enclosure. The Porwedge/EQ option would require more power. Man, 4 cubic feet is not bad. tpaxadpom if you try this I would be extrememly interested in your results!

[thxgoon]

tpaxadpom I just checked out your listening room. Nice amps! I'm drooling

[WmAx]

DS-21 wrote:

That was my bad. I didn't update the Unibox graph from some doodlings with a Maelstrom-X in a vented box. The 120dB figure is actually the paper output of a vented Maelstrom-X alignment, though I don't recall the volume or tuning.

The paper numbers for the Jello 13W7 at 20Hz, per Unibox, are 107.3dB (excursion limited) in a sealed box (Qtc of 0.571, 130L sealed, heavy stuffing); 114.2dB in a vented box (150L, 16Hz tune, heavy stuffing).

Note that the parameters in my file are from a 13W7 that I measured (FuzzMeasure Pro 2.0, MacBook, M-Audio FireWire Solo) and not the stock ones, so other's enclosure numbers may differ. However, I used the spec'ed Sd and Xmax, so max output numbers should be the same.

I would shave off at least a couple of dB to account for slight non-linearity and compression at high power. Not as much as I would assume for other drivers, since the JL is so extremely linear, but of course nothing will have 100 percent linearity at high power and excursion vs. low power signal.

-Chris

[mayhem13]

This was based on a previous post where a PR design was reported to have 120db output at 20hz. I thought it sounded a bit extreme as well but I have no personal experience with this driver and have not had a chance to model it.

Came home from work and checked the numbers. At 250 Liters given manufacturers specs and 2 Acoustic elegance PRs 18" at 3117.5 grams each
OOPs 3,000 watts gives 109.6 db at 10hz. Imagine with room gain !!

Chris, I do value your subjective opinions regardless of how bias they may be.
Since you haven't listened to a PR system as of late, give one a try. AE has the 15" PRs at 1050 grams Fs 4.63hz xmax 2" p to p on sale for $50.00. Two of these would work nicely with a SDX15 if you've got one layin around. I'm gonna model em now with one of those TC sounds closeout twelves from PE. Will post in a different thread. My opinion will be as subjective as possible of course ! LOL.

[WmAx]

mayhem13 wrote:

Came home from work and checked the numbers. At 250 Liters given manufacturers specs and 2 Acoustic elegance PRs 18" at 3117.5 grams each
OOPs 3,000 watts gives 109.6 db at 10hz. Imagine with room gain !!

Chris, I do value your subjective opinions regardless of how bias they may be.
Since you haven't listened to a PR system as of late, give one a try. AE has the 15" PRs at 1050 grams Fs 4.63hz xmax 2" p to p on sale for $50.00. Two of these would work nicely with a SDX15 if you've got one layin around. I'm gonna model em now with one of those TC sounds closeout twelves from PE. Will post in a different thread. My opinion will be as subjective as possible of course ! LOL.

Do you mean you modeled the JL13W7 at 3000 watts? If this is the case, I don't think that is at all an accurate representation of what to expect. I recommend using the driver's rated RMS 1000 watts, and then de-rate the results by another 2 or 3 dB, in order to get something closer to real-world probable performance estimates.

-Chris

[chrismercurio]

My application would be for stereo set of home woofers so if anyone wants to chime in with an opinion on the JL Audio 13W7 and the JBL w15GTI mk2 I'm all ears. I really only believe in sealed alignments so that is what I would be using in either case. My emphasis is on SQ not ultimate SPL, but shaking the house is cool too. The allure of the JL is working in a smaller cabinet and the cone being more durable as I have a mobile child....

Thanks,

C

P.S. The differences between the mobile versions and the HT versions are as follows: "Fathom motor assys are 15 percent larger magnets than mobile versions and Gotham's'are 30 percent larger than their mobile counterpart." That came from JL, I'm not making it up.

[WmAx]

chrismercurio wrote:

My application would be for stereo set of home woofers so if anyone wants to chime in with an opinion on the JL Audio 13W7 and the JBL w15GTI mk2 I'm all ears. I really only believe in sealed alignments so that is what I would be using in either case. My emphasis is on SQ not ultimate SPL, but shaking the house is cool too. The allure of the JL is working in a smaller cabinet and the cone being more durable as I have a mobile child....

Thanks,

C

P.S. The differences between the mobile versions and the HT versions are as follows: "Fathom motor assys are 15 percent larger magnets than mobile versions and Gotham's'are 30 percent larger than their mobile counterpart." That came from JL, I'm not making it up.

There certainly is no problem using the JLW713 in small sealed systems - the discussion here was merely in regards to wasted output potential due to using it in sealed systems. The JL is a good driver, but you can probably save a lot of money and get near equal performance by using other drivers, such as SoundSplinter(TC Sounds re-badges) or AudioPulse(TC Sounds drivers still available at Parts Express) as an example.

-Chris

[chrismercurio]

DS21,

I am interested to see your build with the W15 and the PR's. I'm sure you know they are now available from AE and are very reasonably priced.

I'm not really concerned with the so-called wasted output. I think most, not all, ported systems are noisy if compared with sealed systems. Besides, though not immediately obvious, one can always sacrifice efficiency for flat output to lower frequencies. And/or, add an LT and LOTS of extra power and be just fine. Velodyne and JL do it to great effect, though the credit of the dinky, pant leg flapping, hair trick work definitely goes to Bob Carver.

Thanks for your feedback.

I will pick up a w15 from ebay and slap it in a test cab, give it some power, and see what happens against the 23w scan speak I'm running now. Absolute sound quality....just not quantity.

Best,

C

[thxgoon]

DS-21 wrote:

it's essentially the 2256 15" driver from their Vertec pro systems, albeit I think with a heavier cone.

Man that it one massive driver! Where did you find the info regarding the relation to vertec?