THT Driver, UM15-22 Benefits?
Hello, I am looking for some advice now that the UM15 looks to be in stock again at PE. With the price difference being fairly small, I am in a bit of a self-debate. I've decided to build the BFM THT in 24.5" width and have bought the plans. For now, I'm building one, but might build a clone down the road if I have severe room modes. It will be placed as prescribed along a wall, 18" from the corner in the front of the theater. Here is some of the basic info: 20X20X8 room with one doorway. I want strong low frequency extension around reference level.
Now with all that, I am torn between the RSS 390-HF-4 and the UM15-22. I tried to register for the BFM forums, but I'm still waiting for Bill to let me in.
Does anyone know if there are any low frequency (<20hz) benefits of using the UM? If so, will there be a upper frequency trade off? I do know that this question is about frequencies below tuning, but I don't understand if the UM can help the extension in the THT more than the 390HF.
BTW, I will be using one channel from from a Crown 1502 to drive it from the sub out on my Denon x4200w with XT32
I'd love to hear from Bill Fitzmaurice, but anyone with knowledge about this subject would certainly be appreciated!!
The UM-15 is good to at least 130hz. Did you plan on going higher than that?
The fiber cone will hold up better than metal in a horned/folded box, a lot less likely to deform under high pressures or bottoming.
@notnyt Haven't seen RickJames in a while... :p
I'll probably be crossing around 80hz unless I can not locate the source higher. Got some little Polk Monitor 50 for mains, so I would love to cross higher. But, I was actually a little more interested what effect the UM has below the tuning frequency, under 22 hz I believe.
having built 3 of the THTLP's, a different form factor of the THT, using the 15" recommended driver, RSS 390-HF-4 ,
and yess the 30"ers are full of whoop-A$$, on only BASH 300's
from the forums discussions and feedback from Bill himself, (AFIACR) he didn't design the extension of these for below 20-22 hz output, rolling off very steeply at 22,
now what and how much more you might get from room gain and the use of multiples is getting into your room, placement, and those multiple factors,
others have been impressed for many years
if you're looking for a design ,a design almost guaranteed sub 20 ,
for about the same price as the HF-4 you can get 2 of the PA-460's used in the VBSS builds, tuned to 15 hz
it, VBSS, can be built using 3/4" plywood, heavier than 1/2" as in the THT,
but much much much easier to build . . . ask me how I know,
for the same $400 wrt the amp, a inuke6000dsp could drive 8 or more VBBS's. ask mtg90.
I run my THTLP's off BASH 300's and the gain is like almost a whopping 10%, almost off . .. efficient, clean and sensitive, big and loud
recently while trying to tame 2 of the thtlp's in a small room and play nice with the small mains, my REW sweeps verify the bottom of the design is - as designed .
and VBSS multiples spread around the room will put lots of bass even more smoothly . .
drop a line to @cuzed2 , he's a VBSS builder
and of course there are others
AVS is a great resource
Also, do not use an amp that puts out more than 300w. The THT is designed for only that much power. Doesnt matter what the driver is rated to. It's been discussed at length on BFM forms. The 1502 will put out too much power.
Let me know if you already have the plans. I'm not familiar with the UM15....so maybe it meets the requirements. But, even if it does, you won't get any lower with it vs any other driver because the horns natural tune is around 22hz. And, building it wider will get you a little lower, but nothing the HF can't handle.
I've pushed mine to crazy limits, and they just keep on going. You absolutely do not need a UM15 for a THT.
Typed on a tiny keyboard, excuse any typos
And regarding the amp, I will only be using one channel of the 1502 at 4 ohms. That's rated at 525, but I will certainly have it attenuated and will verify voltages at setup. I am aware of how little voltage is needed with this horn, and that means I might be able to drive a second one of the same single channel of the 1502 and only need a total of two 1502 amps for my planned system. I lose the ability to tune them separate, but they would be placed in the two front corners of the theater anyhow and would be timed the same.
Thanks again for the input!!
Being nearfield, I get a little more out of the low end, but there still isn't much there past 18-20hz.
Good luck. The UM is a beefy driver, so if I was going to build more I'd go that route. That said, the HF works well also.
Typed on a tiny keyboard, excuse any typos
from about 3+ years ago, a pair of 30" THTLP's serenading the neighbors,
because - awesome
iirc, a wider build, per Bill, makes the sub more sensitive
you're gonna love it
and "hit the mark"
the red is only a 24" but after 10 minutes of testing/playing/ cranking it, with no EQ or stuff like that . .
I shut it down.
went to home depot to get the plywood for the 2 x30" build.
The instructions are an amazing piece of work in themselves.
You'll feel like he is in the room, seated comfortably, and watching you like a hawk . .
And if its upgradable (hole fittings and diameter cutout)?
Did the 24 really have that much less versus the 30? I still have to get the wood, and modifying that parameter in cutlist is no biggie......I'm tempted now lol.
i was too thrilled about the sub and a pending retirement to ever do any science
the 24 was in a room of < 100 ft^2, less than 900 ft^3, way waymore than ever needed
( now that room has the 24 and 1 30 in it for my REW work , as I have acquired a few other subs)
but for my Living Room and about 5kft^3 ,2 of the 30's seemed right and i wanted them for my retirement party
and of course, how could bigger and more of them not be better?!?
and just with the BASH 300's they were butt to butt , each mouth loaded up to a side wall, just about the 18" loading distance,
they are so clean,and efficient
Everything folks claim them to be . . even before XT32
now when you get into the room modes and adding 6 dB and smoothing overall bass response,
yes, MAJOR Bang for the Buck
and building 2 at a time sooooooo much easier
How would you compare the 30"LP vs Max V3? Is Max louder or just lower? Graphs look like the LP might do better with a higher XO.
I need to build a new horn but can't decide. I like the type of bass from a FLH.
While both subs are FLH , in the same church: low distortion, sensitive, take power well, no port issues, LOUD!
so to speak . . .
They are not, by any means, in the same pew
the 15" HF vs the UXL 18"
The LP uses 1/2 ply - needs extra attention for proper construction (IITP) and nice and light weight, comparatively, great for most music and about 95% of everything else, versatile placement options
V3 - 3/4 ply, a very easy fast build, but with driver, an easy 300+#.
The LP's , playing the opening to EOT , not so happy with the final 8 -12 seconds but good for what they can do and extremely efficient, BASH 300's being overkill
OTOH : V3 with some good placement and minidsp EQ and about 1400 watts (same for my V2).
"That's what I talkin' about"
give @hd0823 a shout, he has 2 of the V3.
you should have the list of approved drivers by now . .
I've built 3 THTs and still have one in action.
I've seen models showing that a 30" THT can do 125db at 25hz. And it looks like MAX might also top out at 125 at 25hz. MAX should go a solid 5hz lower than the THT. But I'm only after silly EDM bass for my project so the extra extension might not be worth the added size.
I'm wondering if the THT can actually hit 125 or if MAX can actually go beyond that? My THT does fine with a 110hz xo, will MAX get nasty above 80hz?
We need some MAX sweeps.
People get way to into tuning frequency here. I was worried my single alpine type s 15 was going to be worse then my single rss390ho. The rss390ho was tuned to 19 or 21 Hz and the Alpine in the quadhorn was tuned to 24hz. The 2 subs are night and day different, the 24hz is waaaay better. For the 20$ difference in drivers I'd just get the ultimax. It's not like it will be worse then the rss390hf, and you'll have a premium driver in a well proven design. I purchased his plans but never built it, I may get around to it later in life lol.
I'd definitely go as big as you can, because if you build a 24 you'll say "hmmm, wonder what that 30" Sounds like!".
Well, PE made it a no brainer for me. Restocked UM15-22 for $165, with coupon code......155 shipped!!!! Efff yeah!!! :D
when i simulate the RSS390HF*4 and the UM15-22 In a closed 100l box the UM driver outputs about 2-2,5 db more before it reaches xmax at around 22hz.
How will that compare in a horn would that be the same amount of more dB?
Just trying to figure out what gains it would give...
Horns are almost entirely driver-limited. The beefier the driver, the better. (The horn box can handle whatever the driver can withstand...)
1) High Sensitivity
2) High Power Handling
3) Top Notch cooling
5) Inductance management
These 8mm china condenser mics (UMIK/EMM/ECM/Omni etc) start distorting heavily above 120db, and clip at 130db (or less.)
Get a quote on the High-SPL edition: http://spllabusa.com/us/products/nex...icrophone.html
You could also get a NTi or ACO Pacific mic, but those are likely >$1000. Probably well-outside your desired budget...
And just like that, two UM15's are heading my way. I couldn't stop thinking about only buying one when two is mo bettah :D :D :D
With two of them, I will almost be cornered into doing 24.5 width boxes, but hey.......I'll have two of them lol! That little Audiosource 15 I have now is going to crap it's pants.
BTW, thanks AVS forum for the useful info and for being an influence for upgrading before even receiving my first DIY driiver haha!
Somebody lucked out being on Santa's "nice" list,
timing is important too . . .
Good to see you scratching that 'itch' right from the start
don't use any cheap 1/2" but you don't have to go BB either, YMMV
but be prepared to deal with its "bendniess" while trying to stabilize panels during construction
PL3 is the go-to adhesive and it will seal any gapage.
wear disposable plastic gloves
by now you've spent enough time at Bill's site to know: IITP
in the plans, prepping the chamber for the cover panel attachment , iirc, calls for adding some more 1/2" for the screws to hold the cover on . .
this pic - I recessed by a "fat" 1/2" (9/16ths) these solid oak strips, 1 or 1 1/4" by 3/4".
my "thinking' was , yeah, those cover screws going to solid oak, pre-drilled and pre-run and 2 separate lines of 1/2" gasket tape . .
i could space the screws a bit closer knowing that the oak is going to allow substantially better sealing/ holding potential
bodaciously airtight https://www.avsforum.com/forum/images...s/rolleyes.gif
now while that may fall into OCD overkill territory and not following the plans, at least for that final and really, really important necessity,
I also wanted a beefier end as I somehow expected that maybe I would put it on a dolly and point it at the ceiling, it takes a much smaller footprint
such is the ongoing saga of the possibility thinking DIY mentality
remember, this build is actually going to be fun
and yes, from audiocheck.net, the 24 hz tone plays just fine, the 22 is expectedly more subdued.
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