Just checked Hornresp and the 2x15" in a small ported box kills the 1x15 or 1x18, so going to 4 ohm would not matter for my purpose.
PM sent to you.
Yes I was having the problem that the response wasn't quite as good when the driver was even 20cm centre back in the mouth though still acceptable. As you have to cut the baffle hole somewhere this is about the minimum possible last segment. Same at the throat end although it is theoretically possible at least to feed the very start of the throat.
I switched to rear loaded horn combined response pathlength 0 and had less dip which proved there was no advantage to the tapped horn in this case! It's a good idea to check against rear loaded horns to see whether there is an advantage.
I've been having better luck with both rear loaded horns and 'bass pipe' designs than I have a tapped horn. Having a 'band pass' style chamber also seems to smooth out response well. I've been looking at the Faital Pro 15HP1060 as it seems to have similar properties to a pair of isobaric Kappalite 3015LF drivers (as an aside that makes it suited to narrow width BFM T48 'slims' as a premium option). This allows me to scale up a half size vented box, with either a bass pipe or rear loaded horn design. My goal is to have the Faital with 12.5mm Xmax act like the kappalite in a bigger box which would require 17.7mm of Xmax to keep up!
So far my sims show about 126-7dB out of the bass pipe so have gotten round the limiter. The rear loaded horn sim had a nice rising response but was still as good as the bass pipe down low so I think it's a winner. It also flattens out nicely in a corner. Can it be built in one sheet though?
I needed more than one sheet to build an autotuba though so seems like a tough challenge. JBell any bracing in your SS15? I noticed the cut sheet.
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Art,
The God's have not been smiling on me lately and I have been up to my neck in a shitestorm of personal disasters. I hope all is well with you, you old man.
I live in the Great White North and winter has finally hinted that it may be receding. I just got done shoveling through 2-3 feet of snow and chipping out a 2" layer of ice to get the door to my wood shop open. Some sort of building project will start soon. Once the weather warms up a bit more and I get some prototypes built, I plan on doing a test of various designs like the one you did out in the desert. I will likely need your coaching on that.
I still been browsing this forum in my free time, I see you have been helping LostinBass, who seems to be my long lost twin brother. He seems to have keep you entertained in my absence. That is a massive system you are selling - very impressive.
If you come up with any more designs using the Dayton Pro PA385-S, check out another thread I started when I first came here, that way we won't distract from JBells fine SS15 thread.
http://www.diyaudio.com/forums/subwoofers/246698-dayton-audios-new-15-18-pa-drivers-b-c-copies.html
Sine143,
Don't you have a stack of Bill Fitzmaurice's Titan 48's? I would really be interested in how this Dayton Pro PA385-S build of your compares. Speaking of Fitzmaurice, that was one of the sites I had been browsing about a year ago before I became aware of DIYaudio.com. Don't you have a business building subwoofers. On one of these type of web forums you had posted the web address of your personal website and I remember I was impressed with it. If this was you, would you mind posting it again? I built my own variation of Fitzmaurice's SLA Pro's last year and I am pretty happy with them.
Would you be kind enough to give my a hint of what the wholesale discount is on Dayton products? I have used their speakers in quite a few different PA tops and guitar and bass cabinets and for the price, I like them. I am wondering if it would be worth the hassle for myself to get a wholesale account. Is all you need is a Tax ID number, or is there some other screening process or minimum order requited. Thanks
Check out this thead if you want to post any further details of your Dayton PA385-S design and build project:
http://www.diyaudio.com/forums/subwoofers/246698-dayton-audios-new-15-18-pa-drivers-b-c-copies.html
TimLewis,
You remind me of someone that posted frequently on Bill Fitzmaurice's site when I was looking at that about a year ago. Were you AKA TimpBizkit, or something like that? If that was you I really need to thank you, because it was you that I believe made me aware of this site. If I remember correctly, someone was whining about their sub build not performing as expected, and you may have brought up the SS15 design and posted a link to the particular thead??? I just checked back the Fitzmaurice site and it seems you were kicked off there. HAHAHA, I seem to remember you used to get Mr. Fitz pretty riled up.
You seem to understand the science and mathematic of subwoofer design, and have quite a few whacky opinions and ideas to liven things up. Let's not disturb Mr. Bell's fine SS15 thread any further, why don't you whip up some designs using the Dayton Pro PA385-S and post them here:
http://www.diyaudio.com/forums/subwoofers/246698-dayton-audios-new-15-18-pa-drivers-b-c-copies.html
You remind me of someone that posted frequently on Bill Fitzmaurice's site when I was looking at that about a year ago. Were you AKA TimpBizkit, or something like that? If that was you I really need to thank you, because it was you that I believe made me aware of this site. If I remember correctly, someone was whining about their sub build not performing as expected, and you may have brought up the SS15 design and posted a link to the particular thead??? I just checked back the Fitzmaurice site and it seems you were kicked off there. HAHAHA, I seem to remember you used to get Mr. Fitz pretty riled up.
You seem to understand the science and mathematic of subwoofer design, and have quite a few whacky opinions and ideas to liven things up. Let's not disturb Mr. Bell's fine SS15 thread any further, why don't you whip up some designs using the Dayton Pro PA385-S and post them here:
http://www.diyaudio.com/forums/subwoofers/246698-dayton-audios-new-15-18-pa-drivers-b-c-copies.html
Ahhh, Mr. Bell, I believe you also had a cantankerous relationship with Mr. Fitzmaurice as well. You should be proud of Mr. Lewis, I think he caused Mr. Fitz to have upgrade his blood pressure medicine. I am not sure what he did to actually get kicked off (and all his post disappear), but there is still a ongoing thread there dedicated to harassing him now that he can't fight back.
By the way, I wasn't trying to steal your forum posters when i suggested they check out:
http://www.diyaudio.com/forums/subw...5-18-pa-drivers-b-c-copies-6.html#post3793588
I just didn't want you SS15 forum to get off track. By the way though, you had posted on that thread you had purchased the Dayton Pro PA465-S 18" subwoofer. How about dropping by and giving us an update on your experiences with it. it sims pretty well in your SS18 design, got any updates on a new design?
By the way, I have an old Eminence Kappa Pro 15-LF2 I pulled from another cabinet, and my grandson and I are going to build one of your SS15's during his spring break. I will keep you posted. Thanks.
The reason I got the boot is cause of posting a build thread on the umm. Simplexx 12 Sub? I was looking for a temporary reflex box to house a 3012 lf subwoofer and posted a build thread. Got a warning for starting a build thread on a non bfm design. Fair enough.
In Bill's defence I did try to bend the rules by posting the pics up on my Omnitop 12 build while I ws waiting for parts. Maybe I should have built another Autotuba and run them as a pair in the corner.. whether or not it warrants account deletion when it could have been moved to Everything else is debatable. After all, no one cared when I fulfilled requests to see this giant horn I built when I was 19, though that was before I knew much about horns so I just drew a random horn layout and used 2 for 1 jbl gto 1264 drivers in it. Bits of it probably leaked or rattled but I could still shak conservatory windows at 15 volts per woofer on 20Hz! I suspect one could do better in a 4' by 2' by 4' box though.
On the facebook group it seems someone got scared I was gonna recommend some unsuitable expensive drivers for a cab. It was a Kappa 12 woofer they had for free in an Omnitop. Okay the Q was 0.01 below the minimum and the Xmax was only 3mm (so I suppose for very loud outdoor use it's not the best) but the midrange risibg response was there. Some panicky cab builder thought it would burst into flames or something ;-) Harley
In Bill's defence I did try to bend the rules by posting the pics up on my Omnitop 12 build while I ws waiting for parts. Maybe I should have built another Autotuba and run them as a pair in the corner.. whether or not it warrants account deletion when it could have been moved to Everything else is debatable. After all, no one cared when I fulfilled requests to see this giant horn I built when I was 19, though that was before I knew much about horns so I just drew a random horn layout and used 2 for 1 jbl gto 1264 drivers in it. Bits of it probably leaked or rattled but I could still shak conservatory windows at 15 volts per woofer on 20Hz! I suspect one could do better in a 4' by 2' by 4' box though.
On the facebook group it seems someone got scared I was gonna recommend some unsuitable expensive drivers for a cab. It was a Kappa 12 woofer they had for free in an Omnitop. Okay the Q was 0.01 below the minimum and the Xmax was only 3mm (so I suppose for very loud outdoor use it's not the best) but the midrange risibg response was there. Some panicky cab builder thought it would burst into flames or something ;-) Harley
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I think it was a guy called Dan. BFM user Hifibob had a thread called 'I wish I had the opportunity to silence the critics'. I did post something about jbell's tapped horns but it was off topic so got deleted, mind you that thread has turned into a 'who's had the best electric shock?' thread, and Bill hasn't deleted any.. go figure - read Jools4001's shock story it's hilarious!
BillFitzmaurice.info - View topic - I wish I had the opertunity to silence the critics!
Dan had a full range Fearful bass cab and unsatisfied with his 2 Jack 10s and thanking me about the 'deleted post about jbell'. Keeping in BFM mode I also recommended him an Omni 15. I haven't heard a Jack cab but something tells me they are better for twangy bass guitar with powerful mid-bass than an all out hi fidelity tone with deep extension (compared to Omnis). Sure they could be EQ'ed but a 3-way cab is a better starting point.
In my opinion BFM has some very good designs, but others could do with a little work. E.g. I struggle to find an advantage to his Tuba 24 over a Kappalite 3015lf reflex box of the same size, or an SS15. (V-Plated with 2 HL10A in each cab they might be able to hang but then they couldn't win on driver prices). Sure it looks good compared to some random 95dB sensitive Yamaha that rolls off at 60Hz, but if you're not getting at least 98dB sensitivity flat to 40Hz out of a cab that size (easily done with a 6.6cu ft reflex tuned to 40Hz), then it's only good for bragging about what you can do with a 10 inch driver.
I would like to be able to compare 8 of each V-Plated to see if there is any advantage in large groups.
My design fee is £200
jk, sure I'll see if I can whip you something up. Don't know how it'll perform in the real world and I'm not that good at 'folding' and 'unfolding' horns yet.What sort of extension are you looking for and what are your size requirements?
I also wonder why the Simplexx subs seemed to roll off earlier than potentially possible, as in the attachment. Is it to make use of other drivers with lower box size requirements? Is there some destructive wavering of the cone that can happen at high power that Bill knows about but I don't? (Is it to make the Tuba 24 look better?)
Attachments
My design fee is £200
What sort of extension are you looking for and what are your size requirements?
Hey, the check is in the mail Mr. Lewis. Also, I just noticed your post #2018:
http://www.diyaudio.com/forums/subwoofers/170771-single-sheet-th-challenge-202.html#post3853580
Why don't you whip up a variation of that for the Dayton Pro PA385-S 15" subwoofer. Put a design out there and let people pick it apart. I had a forum topic here a while back about designing a tapped horns. It was humiliating sometimes, but the amount of information I gained was completely amazing. This is very different than the BFM forum, where you can't criticize a design. Here critiques are encouraged. There is always someone that is willing to help you understand something that you are having a problem with.
And those triangular ports look interesting. Art, one of the experts here, was the first person I noticed that used those. But I have been doing a lot of design research lately (while I am at "work" HAHA) and it seems everyone from Carvin to D&B to Mr. Fitz himself have started using them in the past year. Teach an old man like me how about the benefits of the triangular ports and how you calculated them.
And your Timplexx15 in post #2052 looks good - I like you word play with the name. Thanks
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The benefits of triangular ports are they allow larger port area when baffle size is limited. When using the corners of the cabinets, like shelf ports they tune lower for a given length than round ducts.
I "calculated" them using an old JBL nomograph to get in the ballpark for length, then adjusted the length until the measured Fb and response was "optimum" for the box size. Turned out the "optimum" tuning was a few dB hot above Fb, as the measurement mic I used at the time (January 2008) turned out to have reduced LF response.
Anyone looking for a used Terasonde Audio Toolbox with a mic deviation correction chart
?Art
Hey Art, Thanks for that info.
I was just thinking that if you used triangular ports in all four corners, and their depth extended at least half the actual cabinet depth, that would also offer excellent structural support for the cabinet. Put some bracing on the back panel and it should be rock solid.
I have played around in WinISD with triangular ports a few times, but I am not sure I am doing it properly. What I would do is calculate the area of a single triangular port as (A = 1/2 * B * H). WinISD doesn't offer a triangular port option, so I would approximate that same area with a square port of equal area. Then I would enter the depth of the port, and change the number of ports to 4. Is that too simplistic? Does the tight corners of the triangle possibly offer more resistance to airflow than a circular or square port? Thanks.
Given the same area, a circular, square, or triangular port all will tune slightly differently. A square, rectangular or triangular port sharing cabinet sidewalls (considered a "shelf port" in some simulators) will also differ from the the same port shapes and area not sharing cabinet sidewalls. Dividing a shelf port in to multiples also changes tunings, every different shape, size and location results in both slightly different tunings and port velocities.
The differences between port simulations and reality can be rather large, as in 1/3 to 2/3 an octave, but are easy to measure using a swept sine wave and watching cone excursion, which is at minima at Fb.
Since simulations for anything but round ports (mounted well away from any cabinet wall) never seem to agree exactly with tunings using different shapes and locations, I now always make the port a bit long and reduce length if the alignment ends up lower than desired. This becomes a bit more challenging when working with ports that vary in cross-sectional area from end to end.
Art
Not sure what you are getting at, but below Fb a candle will be blown out pretty easily, while when the port is not too turbulent, a candle remains lit.