Would like getting input on a project before getting started. Will be used for critical music listening and movies so i need both good SQ and hi SPL.
It's not a normal Subwoofer build. I use crossover to my mains at 80Hz and using separate Amp for mains and "sub", so I am building two of these. Want efficiency and good SPL in the lows for movies, so I am going for a vented box.
I have a decent but basic understanding of how to do this. But I would appreciate input on things like: Dampening box resonances? importance of baffle design?, Dimensions? Maybe Ports too long? And so on.
Vb = 220L (8.5cuft)
fp = 23Hz
three vents whit diameter 100mm (4"). 430mm (16") long
It's not a normal Subwoofer build. I use crossover to my mains at 80Hz and using separate Amp for mains and "sub", so I am building two of these. Want efficiency and good SPL in the lows for movies, so I am going for a vented box.
I have a decent but basic understanding of how to do this. But I would appreciate input on things like: Dampening box resonances? importance of baffle design?, Dimensions? Maybe Ports too long? And so on.
Vb = 220L (8.5cuft)
fp = 23Hz
three vents whit diameter 100mm (4"). 430mm (16") long
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Yes. Front loaded horn. Approx dimensions were 24x24x34. Will post more later with some modeling graphs.
Sorry for the delay guys. The design is a well known one one found here.
Horn Subwoofer
Ive built a few of these already. Decided to test and give it a go. It models very well with a wide variety of drivers. I did find that he was correct in corner loading. You lose the low end roll off by placing it in half space. But when corner loaded.... Whew! A pair of these with td15h's in them would be PLENTY for a large living room or listening room. One of them in my 30x30 garage on a crown xls2000 has managed to irritate my neighbors about a half mile away.
So You will need to modify the original design. The top lid needs to be lifted by 200mm to accommodate driver depth. The one i built were using 18" drivers but the same will need to be done for the 15" drivers. sensitivity is incredible!
Also his design was for 25mm MDF. I made a conversion to 18mm baltic. Its not too tough to do if you shrink down external dimensions to accommodate the smaller thickness. The only dimension you want to have right on the money is the s2 throat. The 50mm and 82mm dimensions need to be kept. The rest can be off the few millimeters from wood thickness with no shift in response. I centered the remaining segments within original 25mm dimensions.
Horn Subwoofer
Ive built a few of these already. Decided to test and give it a go. It models very well with a wide variety of drivers. I did find that he was correct in corner loading. You lose the low end roll off by placing it in half space. But when corner loaded.... Whew! A pair of these with td15h's in them would be PLENTY for a large living room or listening room. One of them in my 30x30 garage on a crown xls2000 has managed to irritate my neighbors about a half mile away.
So You will need to modify the original design. The top lid needs to be lifted by 200mm to accommodate driver depth. The one i built were using 18" drivers but the same will need to be done for the 15" drivers. sensitivity is incredible!
Also his design was for 25mm MDF. I made a conversion to 18mm baltic. Its not too tough to do if you shrink down external dimensions to accommodate the smaller thickness. The only dimension you want to have right on the money is the s2 throat. The 50mm and 82mm dimensions need to be kept. The rest can be off the few millimeters from wood thickness with no shift in response. I centered the remaining segments within original 25mm dimensions.
Attachments
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Now applying 500w or 63v to sims.
response and displacement. With 500w, you could get away with no HPF and let it roll off. Ive noticed from my builds, that this cabinet can dig deeper then modeled. Running thru test tones and a cheap SPL meter, and using my highest point of 52hz as reference, I got my -6db at 27hz and my -3db at 35hz. But of course the room itself will be a big factor. If applying greater then 500w, I would adjust a HPF accordingly. I have HPF set at 35hz/24db but im slightly exceeding drivers recommended RMS.
response and displacement. With 500w, you could get away with no HPF and let it roll off. Ive noticed from my builds, that this cabinet can dig deeper then modeled. Running thru test tones and a cheap SPL meter, and using my highest point of 52hz as reference, I got my -6db at 27hz and my -3db at 35hz. But of course the room itself will be a big factor. If applying greater then 500w, I would adjust a HPF accordingly. I have HPF set at 35hz/24db but im slightly exceeding drivers recommended RMS.
Attachments
Many thanks for the information!
Alas, I don't have the option to corner-load my subs; it will have to be half-space, so I guess this design won't work for my listening room. . . Joel.
How big is your listening room? And how many drivers do you intend to use for it?
I tend to look at efficiency over anything else. A well rounded setup with 106db sensitivity has a different "feel" to it then say a 98db sensitivity setup at the same db level when listening. I call it a musical presence.
My listening room is 42 x 26 feet with 18 foot ceilings.
I do have a pair of dual 18" Tannoy subwoofers (VS218-DR) in 500 litre bass-reflex cabinets, manufacturer-rated at 106 dB sensitivity, but, as the mains are "only" 100 dB sensitivity (Tannoy V300), I just have to dial back the subwoofers.
Also, without significant EQ, the VS218-DR roll off below 40 Hz—which is to say that 106 dB rating is an average over 30 to 200 Hz, but is considerably less than that below 50 Hz. As a result, I am forced to use an equalizer.
What I'm looking for is an f2 of 30 Hz (or better) and if I could achieve 98 dB sensitivity at that frequency, without EQ, I'd be more than satisfied!
I do have a pair of dual 18" Tannoy subwoofers (VS218-DR) in 500 litre bass-reflex cabinets, manufacturer-rated at 106 dB sensitivity, but, as the mains are "only" 100 dB sensitivity (Tannoy V300), I just have to dial back the subwoofers.
Also, without significant EQ, the VS218-DR roll off below 40 Hz—which is to say that 106 dB rating is an average over 30 to 200 Hz, but is considerably less than that below 50 Hz. As a result, I am forced to use an equalizer.
What I'm looking for is an f2 of 30 Hz (or better) and if I could achieve 98 dB sensitivity at that frequency, without EQ, I'd be more than satisfied!
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I personally dont think the TD15H is the route to go then if your looking for a flat response to 30hz. I did a brief model with reflex and 6th order and could not get a response to 30hz with that type of efficiency. I would look into a small tapped horn design. There are few guys with some excellent designs on here. Lilmike's pico and microwrecker have proven themselves to be efficient and with the right driver and minimal eq'ing, will play flat below 30hz.
I have no doubt I can get a flat response to 30 Hz with the TD15H, using a reflex enclosure, but not, as you say, with horn-level sensitivity.
I'll probably end up doing what I did with the JBL 2235H—two drivers per channel in 10-12 cu.ft. With the boost from two drivers and the increased amp output from halving the impedance, the effective sensitivity will be close to 100 dB, which matches the Tannoy SuperDuals I'm using very well.
Coincidentally or not, the TD15H has virtually identical sensitivity, Fs, Vas and Qts as the 2235H, but with the advantage of much higher power handling, much lower inductance, and considerably larger Xmax.
Ultra high horn sensitivity would be nice, but, as I said, not much point in having to suppress a lot of it to match the mid-hi modules.
In any case, the TD15H are ordered and paid for. . .so, as they say, I'll dance with the one I brung. . .
In any case, many thanks for alerting me to the horn option. I'll revisit that when I look at a LF option (below 300 Hz) for my next project: the B&C DCX464 coaxial compression driver.
I'll probably end up doing what I did with the JBL 2235H—two drivers per channel in 10-12 cu.ft. With the boost from two drivers and the increased amp output from halving the impedance, the effective sensitivity will be close to 100 dB, which matches the Tannoy SuperDuals I'm using very well.
Coincidentally or not, the TD15H has virtually identical sensitivity, Fs, Vas and Qts as the 2235H, but with the advantage of much higher power handling, much lower inductance, and considerably larger Xmax.
Ultra high horn sensitivity would be nice, but, as I said, not much point in having to suppress a lot of it to match the mid-hi modules.
In any case, the TD15H are ordered and paid for. . .so, as they say, I'll dance with the one I brung. . .
In any case, many thanks for alerting me to the horn option. I'll revisit that when I look at a LF option (below 300 Hz) for my next project: the B&C DCX464 coaxial compression driver.
A query about the AE TD15H that may qualify for the "dumb question of the day"—
My pair, just received from AE, come with rubber "gaskets" (for want of a better word) that cover the edges of the frame, front and back, though they are not attached and can be readily removed.
What I don't know is whether these are only to protect the driver frame in shipping, or whether they are intended to create an air seal when mounting the drivers.
Clarification from resko1 or others familiar with the TD15H would be most appreciated!
Thanks! Joel.
My pair, just received from AE, come with rubber "gaskets" (for want of a better word) that cover the edges of the frame, front and back, though they are not attached and can be readily removed.
What I don't know is whether these are only to protect the driver frame in shipping, or whether they are intended to create an air seal when mounting the drivers.
Clarification from resko1 or others familiar with the TD15H would be most appreciated!
Thanks! Joel.
That's exactly what I'll be using, but with the TD15H.
May I ask what number and size of ports are you using to achieving a 30 Hz box tuning?
Also, if you could think back to when the drivers were first delivered to you, what did you do with the rubber frame-covers? On which please see my previous post.
I can't decide whether those frame-covers are just for protection during shipping or whether they're supposed to act as gaskets to achieve an air-tight mounting.
Thanks! JT.
Hey Joel,
They are indeed the air seal gaskets for the driver. Similar to a car audio woofer. They work well except whenfront mounting. I prefer a cork gasket then.
Travis
Hi Travis,
Many thanks for the clarification.
As I'll be front-mounting the drivers, this is very timely info!
Regards,
Joel.
Hello again, resko1
I'm now reconsidering the horn design you recommended for the AE TD15H.
I figure that if rear-wall loading won't reinforce the lowest octaves sufficiently, I can always use my TAD TL-1801 subs for below 50-60Hz.
Is there other technical information available on the cabinet build—that is, in addition to what you have already so kindly published here?
I myself don't have the tools or skills to build the cabinets, but the fellow I bring my cabinet plans to (stewartspeakersystems.com) has built numerous horn-loaded cabs over the years. I just want to supply him with as much relevant information as possible.
Many thanks again! Joel.
I'm now reconsidering the horn design you recommended for the AE TD15H.
I figure that if rear-wall loading won't reinforce the lowest octaves sufficiently, I can always use my TAD TL-1801 subs for below 50-60Hz.
Is there other technical information available on the cabinet build—that is, in addition to what you have already so kindly published here?
I myself don't have the tools or skills to build the cabinets, but the fellow I bring my cabinet plans to (stewartspeakersystems.com) has built numerous horn-loaded cabs over the years. I just want to supply him with as much relevant information as possible.
Many thanks again! Joel.
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