Perhaps I should list my past diy subwoofer indulgences in chronological order
1. An old my car subwoofer in a tall el-pipo style stuffed transmission line subwoofer - woofer was pathetic - fail
2. Adire shiva 12 in the same sonotube contraption - driver was good and had a lot of low bass but a room mode sucked out all the midbass - partial success
3. Adire shiva 12 in a 135 liter ported sonotube tuned to 18 Hz. Worked very well until I started experimenting with horn subwoofers and other high efficiency designs - success ( unless you consider the ceiling light fixture that it shook loose)
4. Bill Fitzmaurice autotuba with mcm-2421 - my first truly impressive subwoofer down to 50 Hz - success. Eventually sold the cabinet when I built the next sub.
5. Bill Fitzmaurice table tuba. A bit muddier and significantly larger that the auto tuba, but goes down to just under 30 Hz . Kicks butt and takes names. I still use this sub to date. - success
5. U, W , flat and ripole style based designs using Pyle ppa15 woofers. The ripole was the worst and the others were better but not upto my horn subwoofer standards.
6. T-tqwt with Tangband w69 elliptical woofer. Rough prototype . Very. Good down to 30 Hz but couldn't compete with the table tuba in dynamics
7. Ripole with adire shiva - fail again.
8. T-tqwt using adire shiva . Gets down into the low 20 Hz region but not as efficient as the table tuba. My mains are over 95 db/w/m so the horn loaded table tuba stays. Since then, I've lent it to several friends and paired with a cheapo 100w foster plate amp , it has equalled or embarrassed several conventional subs made with expensive drivers (Dayton ultimax 15, tx sounds 12, Dayton 15 HO , epic with dual drivers - don't remember the model). Success
13. Dual tapped horns with Pyle copies of eminence kappa 12. Great but I could only get one octave or so out of them and they were done by 50 Hz. Partial success
13. Push push bass reflex with close out bravox 6" drivers . Not bad , but didn't measure up. It was just a rough prototype anyway
15. 20 Hz Double bass reflex for Dayton 15 HO . I must have screwed this up because there was no midbass. Rebuilt as a 25 Hz single bass reflex with more emphasized midbass . Good but still embarrassed by the shiva t-tqwt on extension though it might be a little clearer. The shiva is over 10 years old at this time. Success
16. Dual Slot loaded open baffle subwoofer using close out zalytron 1201pl woofers. Very nice but too large and not efficient enough . Considering pairing these with a small Tangband full range if I can find a place to put them. Success
I also built a karlson k15 a few years ago but I only had one suitable woofer . It certainly was a lot of fun but could only get 50 Hz out of it with the vintage. University c15w so wasn't worth the effort as a subwoofer
Hope that helps..
Last edited:
Oops,.. Forgot one. I also built a little T18 horn sub for a friend. Didn't work out in his room so I have adopted it. It's one of my favorites, as long as it works in a particular room and the source doesn't demand much below 40 HZ
You are further down the path than I am
Jeez Zobs, you are a prolific do-it-yourselfer. I am impressed. Even if you count my first two subs (the sonotube and the flexible duct), I am only up to #4. So far, one awaiting a bonfire. I am already souring on my Frankenclosure [TM*] (a conventional 24" cube with two 15" Alpines stuck in it.) I just can't get rid of all of the resonances. I am not sure what my next build will be but I'm quite sure it will be super-thick, two layers with CLD layer. Not that my present one works, but hey it's a prototype!
*Not really but looks cool.
Jeez Zobs, you are a prolific do-it-yourselfer. I am impressed. Even if you count my first two subs (the sonotube and the flexible duct), I am only up to #4. So far, one awaiting a bonfire. I am already souring on my Frankenclosure [TM*] (a conventional 24" cube with two 15" Alpines stuck in it.) I just can't get rid of all of the resonances. I am not sure what my next build will be but I'm quite sure it will be super-thick, two layers with CLD layer. Not that my present one works, but hey it's a prototype!
*Not really but looks cool.
24" cube is about 8 cu ft. nominal. 2 ft x 2ft is a bit large of a mounting surface for a 15" driver. The (2) mounting surfaces are gonna be exposed to a lot of motor stress and will want to vibrate like a drum skin.
Not saying that you should, but (as an example) if you ever chose to rebuild this with the same nominal volume, consider a different aspect ratio such as 1.5 ft x 1.5 ft x 3.5 ft, mount the drivers on the 1.5 x 1.5 face (which should be doubled up in thickness) and use "holey" or "window" braces every 8" along the 3.5 ft length.
bracing - circle or square holes? - Home Theater Forum and Systems - HomeTheaterShack.com
Live and learn...
Yeah, well at least the current 24" Frankenclosure "works". I even opened her up and re-glued and screwed down some of the braces. Here is a simple test: if I can wrest loose one of the 1x2's bare handed, it's probably not adequatelly bracing the boards 🙂
I'd still like to do a "real" TH or similar some day, the current one is just a stopgap that would actually work. I still have a rattle or two and waiting for the next fit of pique to open up the patient 🙂
Your suggestion (different box dimensions) has merit. It occurs to me that if I am going to do sealed box and ugly, why not just order another bigger Sonotube and stick a driver at each end? Lessee...if I stay at 8 ft^3, that would be 114 cm if I did the math right (16" tube) which gives a half-wave (?) resonance around 150 Hz where it might make trouble 🙁
Yeah, well at least the current 24" Frankenclosure "works". I even opened her up and re-glued and screwed down some of the braces. Here is a simple test: if I can wrest loose one of the 1x2's bare handed, it's probably not adequatelly bracing the boards 🙂
I'd still like to do a "real" TH or similar some day, the current one is just a stopgap that would actually work. I still have a rattle or two and waiting for the next fit of pique to open up the patient 🙂
Your suggestion (different box dimensions) has merit. It occurs to me that if I am going to do sealed box and ugly, why not just order another bigger Sonotube and stick a driver at each end? Lessee...if I stay at 8 ft^3, that would be 114 cm if I did the math right (16" tube) which gives a half-wave (?) resonance around 150 Hz where it might make trouble 🙁
TO dredge up an older post, I'd still recommend you consider something like Bjorno's suggestion (http://www.diyaudio.com/forums/subw...-build-his-1st-tapped-horn-8.html#post3847642 ), It will only require a single driver (and is not that much harder than a box to build - plus is self bracing if thought out correctly). I could probably work out an actual enclosure plan for you from the simulations IF / WHEN you're serious about it.
Thanks, that will be in the future...
I'm having too much fun with my Frankenclosure right now. Today I made it "ported". 15 minutes to cut a 4" hole and glue on a 50 cm length of 4" pipe I had on hand. At least I arrived at this from hornresp sims -- claims I can get 14 Hz tuning. Sounds ok so far, no "chuffing" but as I understand it, a LLT only begins to work really low, and not much music down there. Meanwhile, my NU6000 went on strike so off to repair shop it goes (conveniently, one downtown Tampa).
I created a draft "advertisement" I thought I'd share. Hope it is not in too bad taste. I do not want to incur the Wrath of Mod any time again soon 🙂 I will post in the next message (if any) ... if it's not there, it did not meet Standards.
I'm having too much fun with my Frankenclosure right now. Today I made it "ported". 15 minutes to cut a 4" hole and glue on a 50 cm length of 4" pipe I had on hand. At least I arrived at this from hornresp sims -- claims I can get 14 Hz tuning. Sounds ok so far, no "chuffing" but as I understand it, a LLT only begins to work really low, and not much music down there. Meanwhile, my NU6000 went on strike so off to repair shop it goes (conveniently, one downtown Tampa).
I created a draft "advertisement" I thought I'd share. Hope it is not in too bad taste. I do not want to incur the Wrath of Mod any time again soon 🙂 I will post in the next message (if any) ... if it's not there, it did not meet Standards.
Not enough power?
My Frankenclosure is working ok...but...
It's not loud enough! Ok, first let me admit that I don't have any measurements to back up the claim. I do have a REW + measurement mic but not calibrated. In any case, I find it a bit anoying that I have dual 15" woofers in a (maybe) ported box, driven 4 ohm bridged via a iNuke NU3000 and I can peak the meters (supposedly, 3000 watts) and while the bass is a' thumpin', I subjectively don't get the volume I did with the 12" single driver in the Sonotube! Could it be that I EQ'ed the sub too low? Also subjectively, there is relatively less mid-bass and more very low. My x-over is at 80 Hz. With two 15" s I should be having paintings rattle off the walls, cracks appearing in my foundation, fillings coming loose...?
I'm starting to understand why some of us keep building more subs 🙂
My Frankenclosure is working ok...but...
It's not loud enough! Ok, first let me admit that I don't have any measurements to back up the claim. I do have a REW + measurement mic but not calibrated. In any case, I find it a bit anoying that I have dual 15" woofers in a (maybe) ported box, driven 4 ohm bridged via a iNuke NU3000 and I can peak the meters (supposedly, 3000 watts) and while the bass is a' thumpin', I subjectively don't get the volume I did with the 12" single driver in the Sonotube! Could it be that I EQ'ed the sub too low? Also subjectively, there is relatively less mid-bass and more very low. My x-over is at 80 Hz. With two 15" s I should be having paintings rattle off the walls, cracks appearing in my foundation, fillings coming loose...?
I'm starting to understand why some of us keep building more subs 🙂
Problem solved!
Did some elementary troubleshooting: "Gee, what about the polarity of the two drivers?" Sure enough, one is wired out of phase. Sub works gooder with both drivers pushing "out" or "in" at same time
Now port is working and bracing is not 🙂 This looks like a job for Dr. Soldermizer and his Gorilla Glue! Alas, will have to wait until more bracing wood can be obtained.
Did some elementary troubleshooting: "Gee, what about the polarity of the two drivers?" Sure enough, one is wired out of phase. Sub works gooder with both drivers pushing "out" or "in" at same time
Now port is working and bracing is not 🙂 This looks like a job for Dr. Soldermizer and his Gorilla Glue! Alas, will have to wait until more bracing wood can be obtained.
I use wedge braces and PL PREMIUM polyurethane glue tubes for the same purpose ( expands on curing)
I did buy a tube of PL something-or-other. It does work, but I find the Gorilla squeeze bottle convenient for my hunt-and-brace method. I enjoy walking around a home improvement store, but man it takes some time to choose from among the huge variety of (say) construction adhesives on offer. I've read that having too many choices can actually be a negative thing...people just accept the default. Let's see, in Lowe's that would be good old Elmer's white glue I guess 🙂 Apropos of nothing, I looked Googled "Colgate toothpaste", which I don't use, and there are 33 varieties if I counted correctly. I still haven't seen the "hurricane nut" but I did find "T-nuts" on one expedition. Information overload is not confined to retail: for a Spanish exam this coming week, my study buddy, a history buff, is (in my opinion) delving far too much into background that was not even taught by the prof and unlikely to appear in the exam.
Latest evil idea (not yet done): I ran hornresp today and foudn that if I circumcise my port to 7.5 cm, it will theoretically be flat to 28 Hz instead of droopy to 12 Hz or whatever the 50 cm allegedly offers 🙂
Latest evil idea (not yet done): I ran hornresp today and foudn that if I circumcise my port to 7.5 cm, it will theoretically be flat to 28 Hz instead of droopy to 12 Hz or whatever the 50 cm allegedly offers 🙂
Last edited:
Hi Soldermizer,
While you're nipping and cutting on the duct, how about cutting the present duct in half, and making it two ducts with half the length?
For the hurricane nuts look at Parts Express.
Regards,
While you're nipping and cutting on the duct, how about cutting the present duct in half, and making it two ducts with half the length?
For the hurricane nuts look at Parts Express.
Regards,
Mazel tov!
Hi tb46: too late (see below) and a question; then would 2 ports each 25 cm equal one at 50 cm? Even if so, I did not hear any "chuffing" from the 50 cm port.
In any event not having assaulted my sub for two days (latest bracing seemed to work! Yay!) I re-ran my sims and decided to "circumcise" the port down to 7.5 cm (3") and re-EQ the MiniDSP. If the sims are right, I now can get pretty much flat from 26 Hz up to 100+ (I x-over at 80 currently) and 95 db /1 watt. Even w/o a LPF, the sims claim that the drivers won't exceed their Xmech all the way down to DC 🙂
Hi tb46: too late (see below) and a question; then would 2 ports each 25 cm equal one at 50 cm? Even if so, I did not hear any "chuffing" from the 50 cm port.
In any event not having assaulted my sub for two days (latest bracing seemed to work! Yay!) I re-ran my sims and decided to "circumcise" the port down to 7.5 cm (3") and re-EQ the MiniDSP. If the sims are right, I now can get pretty much flat from 26 Hz up to 100+ (I x-over at 80 currently) and 95 db /1 watt. Even w/o a LPF, the sims claim that the drivers won't exceed their Xmech all the way down to DC 🙂
Those 2 drivers really want to be in a circa 10 cuft enclosure. You have something around 7.5 cuft (i"m guessing). Either way, a port tuning of about 25 Hz seems about right.
Attachments
- Status
- Not open for further replies.