So all this playing around with a cheapie JBL sub has me thinking once again about building a good sub or set of subs for my Hales Revelation 3's. The problem i have with most subs is that they don't seem to play well down where i think they should. most store bought types seem to be designed to have lots of 40-50hz boom. The hales -3db point is 29hz reportedly and they do play very VERY well down low and CLEAN! to the extent that i have never really felt a need to have sub. however playing with these crappy subs has me wondering if I could actually build a high quality sub that would start where the Hales start falling off and continue down to the seismic range??
Years ago when i considered this. my thinking was a pair of subs each with 2x 12" drivers. something like the Dayton high output subs. But looking at the specs. the 20hz FS point makes me wonder if they are really up to the task?
I once saw the specs for the custom drivers Hales used in the Rev 3's and they are a 10" with a FS of 14hz! So that makes me wonder what the -3db point would be with a FS of 20hz?? granted i am leaving a lot out here. My first thoughts would be to build sealed cabs like the Rev's to keep that ultra clean low end. But if we are only talking about a small range of what? 20-30hz? a ported system might be the best option.
Or maybe a single 18"???
Or maybe i just buy a Bag End ELF system??
Zc
Years ago when i considered this. my thinking was a pair of subs each with 2x 12" drivers. something like the Dayton high output subs. But looking at the specs. the 20hz FS point makes me wonder if they are really up to the task?
I once saw the specs for the custom drivers Hales used in the Rev 3's and they are a 10" with a FS of 14hz! So that makes me wonder what the -3db point would be with a FS of 20hz?? granted i am leaving a lot out here. My first thoughts would be to build sealed cabs like the Rev's to keep that ultra clean low end. But if we are only talking about a small range of what? 20-30hz? a ported system might be the best option.
Or maybe a single 18"???
Or maybe i just buy a Bag End ELF system??
Zc
getting good bass...
Maybe you should consider building a free-air sub. There are many good drivers available for this purpose - one that I have experience with is the Exodus Audio DPL-15. But there are other options.
Avantages: excellent extended bass response, well below 20 Hz. Reduced distortion. No need for fancy electronics or boost circuits. Good transient response (e.g. similar to a Q=0.707 sealed box).
Disadvantages: you will need to do some "remodeling" and the subwoofer becomes part of your home, more or less. You will need a large space adjacent to the listening space (this could be outside the house if the climate is moderate). I use a large attic space for my free air sub. You need to securely mount the driver - often people mount it in to the wall studs, however I have found that this does not provide all that much bracing.
The idea is to take a high-excursion, high Qts (e.g. around 0.7 or even higher) low Fs driver and mount it in such a way that it is in an infinte baffle "enclosure" where Vb >> Vas. In that limit, Q and Fs are approximately what you get in free air, thus the name. If you use a wall, be prepared to add bracing and/or mass damping to the wall separating the listening space and the "box". A wall in a typical home in the USA is NOT like a MDF enclosure and is easy to "excite", which is not desirable! To reduce vibration somewhat, you can use pairs of drivers mounted face to face so that vibrations cancel.
This might get you the type of bass response that you are after, if you can build it. Good luck
-Charlie
Maybe you should consider building a free-air sub. There are many good drivers available for this purpose - one that I have experience with is the Exodus Audio DPL-15. But there are other options.
Avantages: excellent extended bass response, well below 20 Hz. Reduced distortion. No need for fancy electronics or boost circuits. Good transient response (e.g. similar to a Q=0.707 sealed box).
Disadvantages: you will need to do some "remodeling" and the subwoofer becomes part of your home, more or less. You will need a large space adjacent to the listening space (this could be outside the house if the climate is moderate). I use a large attic space for my free air sub. You need to securely mount the driver - often people mount it in to the wall studs, however I have found that this does not provide all that much bracing.
The idea is to take a high-excursion, high Qts (e.g. around 0.7 or even higher) low Fs driver and mount it in such a way that it is in an infinte baffle "enclosure" where Vb >> Vas. In that limit, Q and Fs are approximately what you get in free air, thus the name. If you use a wall, be prepared to add bracing and/or mass damping to the wall separating the listening space and the "box". A wall in a typical home in the USA is NOT like a MDF enclosure and is easy to "excite", which is not desirable! To reduce vibration somewhat, you can use pairs of drivers mounted face to face so that vibrations cancel.
This might get you the type of bass response that you are after, if you can build it. Good luck
-Charlie
Something I've heard of, but never tried:
Get a driver with a rubber/foam surround, (around 8-10"), then cut out triangles from the spider (maybe 3/4" equilateral triangles, on in each quarter). This greatly reduces Vas, and lowers resonance too, making for a very small box that goes very low. The disadvantage is that you'll quickly bottom out the driver at anything more than normal listening levels.
Disclaimer now - I've never tried that, only heard of it.
You say you want to go from 30Hz down, so I immediately thought "bandpass enclosure" - they have good efficiency over a fairly narrow band, so it may be worth a look......
Chris
Edit - just noticed - you're after high output, which discounts the first idea...
Some PR cabinets would probably do what you're asking...
Get a driver with a rubber/foam surround, (around 8-10"), then cut out triangles from the spider (maybe 3/4" equilateral triangles, on in each quarter). This greatly reduces Vas, and lowers resonance too, making for a very small box that goes very low. The disadvantage is that you'll quickly bottom out the driver at anything more than normal listening levels.
Disclaimer now - I've never tried that, only heard of it.
You say you want to go from 30Hz down, so I immediately thought "bandpass enclosure" - they have good efficiency over a fairly narrow band, so it may be worth a look......
Chris
Edit - just noticed - you're after high output, which discounts the first idea...
Some PR cabinets would probably do what you're asking...
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Double the compliance, double the Vas and Fs drops ~26% if I did the math right, so cutting up the spider increases compliance, ergo *increases* Vas which in turn lowers Fs for a given moving mass and *increasing* cab Vb proportionately for a given Fb same as when multiple drivers are used in a common cab, i.e. double the drivers, double the net Vb required for a given alignment. Taken to its extreme is to make a string weave spider like some DIYers do to make super high compliance PRs from blown drivers once the magnet assembly is removed.
GM
GM
There's more than one way to approach this, so Charlie's IB and the BagEnd alignments are both viable, but once you've experienced compression horn (sub) bass there really is no other alignment if space, budget isn't an issue, so until recently this option was only for the wealthy few and/or really serious DIYer. Second best is 4th order BP, then IB or TL alignments that mimic them.
The tapped horn and tapped TQWT (6th order BPs) or even the basic tapped pipe has changed the pecking order by merging the 4th order BP with the TL to create hybrids that can yield high SQ compression (sub) bass horn performance over a relatively narrow BW in a much smaller bulk, so ideal for filling the lowest octaves of a typical sound system, though still relatively large if designed for true sub bass output at ~live levels for music or DD/DTS/THX HT reference levels.
GM
I live in a rented townhouse so mounting drivers in walls just isn't an option! There is a permanent residence in my future but I still would want the subs to be a contained type system. I once had a JBL B460 sub. single 18" in a 8cu cab. that's about as large as i would want to go for a single sub. For a pair I was thinking something maybe 30-36" high by 14-16" wide by 24-36+ deep. and those numbers are just thinking aloud. no real math done.
The Rev 3's aren't real efficient. But they will get to 100+ db easily. i forget what the actual numbers are but I think it was around 84-86db 1 watt 4 ohms. and I run them with a 200wpc amp and have seen the clip lights flash...well...often LOL! So for a design goal i would want to be able to hit at least 105-110db at 20hz clean. no huffing, chuffing, puffing sounds. just suddenly the whole room moves sort of thing.
Zc
The Rev 3's aren't real efficient. But they will get to 100+ db easily. i forget what the actual numbers are but I think it was around 84-86db 1 watt 4 ohms. and I run them with a 200wpc amp and have seen the clip lights flash...well...often LOL! So for a design goal i would want to be able to hit at least 105-110db at 20hz clean. no huffing, chuffing, puffing sounds. just suddenly the whole room moves sort of thing.
Zc
You're looking to moving lots of air very far if you want any output at all at 20Hz.
Seeing as you're in rented accomodation, hitting those SPLs at that volume may not be a good idea. Think structural damage if you're not careful.
I'd still insist that a bandpass design is the way to go. Or some kind of super-horn. You could even paint a big S on it........
Seeing as you're in rented accomodation, hitting those SPLs at that volume may not be a good idea. Think structural damage if you're not careful.
I'd still insist that a bandpass design is the way to go. Or some kind of super-horn. You could even paint a big S on it........
110dB @ 20Hz
Hi,
Or maybe the LAB12: look at Posts #2231 and #2233 in the Collaborative Tapped Horn project:
http://www.diyaudio.com/forums/subwoofers/97674-collaborative-tapped-horn-project-224.html
Maybe that will get you started.
Regards,
Hi,
Or maybe the LAB12: look at Posts #2231 and #2233 in the Collaborative Tapped Horn project:
http://www.diyaudio.com/forums/subwoofers/97674-collaborative-tapped-horn-project-224.html
Maybe that will get you started.
Regards,
Hales Revelation Three _ Sub
Hi,
Stereophile has a nice article about the Hales Revelation Three:
Stereophile: Hales Revelation Three loudspeaker
I did once simulate a bunch of MCM 55-2421 in Hornresp, but could never find one I really liked on paper. May just be me. Enclosed is one I'll probably build one of these days, its about the specified size and SPL. I do like the dual configuration for its distortion cancelling properties.
Regards,
Hi,
Stereophile has a nice article about the Hales Revelation Three:
Stereophile: Hales Revelation Three loudspeaker
I did once simulate a bunch of MCM 55-2421 in Hornresp, but could never find one I really liked on paper. May just be me. Enclosed is one I'll probably build one of these days, its about the specified size and SPL. I do like the dual configuration for its distortion cancelling properties.
Regards,
Attachments
I just picked up a pair of TB W8-740C's. I've used the 55-2421 in the past, and the Tang Band is built much better for not too much more $$. I assume the Trio 8 is another big step up, given that the TB doesn't have the flattest BL. Upon further reflection, they are the direction I'd probably go.
GM, do you have any favorite TH sims for these little guys? This project will follow a couple of others, but I'm trying to decide between a single cabinet with the drivers in a push pull arrangement (to help with that not-so-flat BL curve). But, I'm drawn to the idea of single TH's in the corners. They'd be easier to move and need less bracing, in addition to looking cool. The thought of building the sort of internal manifold required for push-pull worries me too, as I see that TH's require careful dimensioning. I've been simming a few in HR, but I am no master.
Hopefully this isn't thread-jacking ZC!
Paul
Wild Burro Audio Labs - DIY Full Range Speakers
Not really, I mean there's a number of ways to adapt ML's math to THs and some are better than others for getting the max SPL for a given gain BW, bulk that look good enough in a sim, but FWIW, TD mentioned recently that after much fiddling he's settled on the SPUD, DTS-10 design routine, at least for HIFI/HT apps, so my other ways may not pan out as well, but until if/when I get a chance to build/measure as he's done...........
Anyway, assuming I understand enough of what he's doing, it doesn't allow a lot of driver specs latitude and if there's any truth that the W8-740 is what's in the SPUD and the published plans are the final version, then all the nice ~flat sims that a number of us have pumped out are way off as it sims a Rocky Mountain profile ~like the one in the patent that I assumed at the time was intentionally misaligned to throw folks off, but now I'm not so sure.
I guess your best option then is to read up on the SPUD and build it using the DTS-10 kit thread's build pictures as a guideline for bracing/damping if you're satisfied it's the right driver for it and their layout solves the problem of how to easily deal with a push-pull manifold. If you want to do singles, then lay it out using half its CSA along its path-length.
GM
Anyway, assuming I understand enough of what he's doing, it doesn't allow a lot of driver specs latitude and if there's any truth that the W8-740 is what's in the SPUD and the published plans are the final version, then all the nice ~flat sims that a number of us have pumped out are way off as it sims a Rocky Mountain profile ~like the one in the patent that I assumed at the time was intentionally misaligned to throw folks off, but now I'm not so sure.
I guess your best option then is to read up on the SPUD and build it using the DTS-10 kit thread's build pictures as a guideline for bracing/damping if you're satisfied it's the right driver for it and their layout solves the problem of how to easily deal with a push-pull manifold. If you want to do singles, then lay it out using half its CSA along its path-length.
GM
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