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post #1 of 9 Old 09-18-2019, 10:00 AM - Thread Starter
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Another UM18 question

As much as I love my v3600s, I'm looking to dive into the DIY market for some extra oomph on the low end.
I'm looking at the UM18-22 subs since PE is running it's special pricing again.
My question is, will two of them be enough to add a substantial amount of output where the v3600s fall off?
Free reign on cabinet size, so I can make them as big as needed. I've just never gone the DIY route before and I'm wondering if two of them will be enough for the low teens/high single digit range? I want something that will compliment the v3600s below where they start to fall off.

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post #2 of 9 Old 09-18-2019, 10:29 AM
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Hi Bill,


How large is the room? Getting into the upper single digits requires some pretty serious displacement or awesome room gain. Two UM18s loaded in Full Marty cabinets will do well into the mid to low teens. Chasing single digits gets expensive. Each octave you go down requires four times the displacement to achieve the same efficiency level.



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post #3 of 9 Old 09-18-2019, 11:18 AM - Thread Starter
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Quote:
Originally Posted by Red Five View Post
Hi Bill,

How large is the room? Getting into the upper single digits requires some pretty serious displacement or awesome room gain. Two UM18s loaded in Full Marty cabinets will do well into the mid to low teens. Chasing single digits gets expensive. Each octave you go down requires four times the displacement to achieve the same efficiency level.

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I'm not home to measure, but going off memory the total room is around 3500 cu ft. The dual v3600s do well currently, but I know they fall off pretty good in the mid teens. I'd like to find a way continue the feeling in to the low teens/high single digits. There's another local to me that has some v3600s and v3611s, as well as a JTR 4000ULF. He did some testing on them and said the JTR had a lot more output below 20hz and got down to like 7.5hz in room. I would like to create something similar to this, while adding it to my current v3600s.

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post #4 of 9 Old 09-18-2019, 01:09 PM
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I do have a 6th order bandpass design that is mostly fleshed out. It is meant to do low end and then have MBMs take over past 30Hz. I have a sim of a similar design with less extension, and more SPL and better excursion control than this one. Life has been too busy for me to get all the designs in CADs and fully fleshed out. This one does get a lot of excursion out of the UM18 without cooking the voice coil too quickly. 1200 watts of power if I recall correctly.



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You can always turn it down, but you can only turn it up so much (before you run out of power, excursion or structural integrity).
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post #5 of 9 Old 09-18-2019, 01:28 PM - Thread Starter
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Quote:
Originally Posted by Red Five View Post
I do have a 6th order bandpass design that is mostly fleshed out. It is meant to do low end and then have MBMs take over past 30Hz. I have a sim of a similar design with less extension, and more SPL and better excursion control than this one. Life has been too busy for me to get all the designs in CADs and fully fleshed out. This one does get a lot of excursion out of the UM18 without cooking the voice coil too quickly. 1200 watts of power if I recall correctly.

So....what you're saying is that I should have you build my enclosure for me? Sounds like a good plan!
In all seriousness, the building portion will probably be my biggest hurdle. I know there's a few guys in the area that do a lot of DIY stuff, hopefully I can convince one or more to show me their ways when I get to the actual building phase in the next month or so. It's nice to see a pair of UM18 might be able to accomplish what I need though, thanks!

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post #6 of 9 Old 09-20-2019, 08:00 AM
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I'm no expert here, but in your space, those v3600's are crushing it already... you already have 4 18" ported drivers hitting hard to the upper teens...

I think you need to up the driver size to get you where you want if what you have isn't doing it in 3500 cuft.... I'd look at some of the 21 inch designs based on the Emminance, LaVoce, or iPal drivers, though at that point you are almost in HS-24 territory, especially since Nick would likely cut you a deal if you are buying 2...

I'm not sure what you are missing with what you have though... if its the tactile stuff, you could look into a BOSS, or transducers... if you want "pressurization" into single digits below what you have, I'm thinking you need to add a zero to the end of the number of drivers you need to really notice a huge difference, or like I said, move up to the really big stuff... though with the sale prices you can get 3 um18's for the price of the Emminance or LaVoce drivers... You did say you have lots of space, right?

In all seriousness on the um18, I recall someone else is building a sonotube ported design with it tuned around 11Hz using a 24 inch sonotube about 6 feet tall, and an 8 inch sonotube as the port... models pretty well, but you'd definitely need to cross it over to the v3600's pretty low to ensure 1st port resonance isn't an issue...

good luck, sounds like you may be on the path to building something very epic... can't wait to see what it is...

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post #7 of 9 Old 09-20-2019, 08:37 AM
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Quote:
Originally Posted by jcr159 View Post
In all seriousness on the um18, I recall someone else is building a sonotube ported design with it tuned around 11Hz using a 24 inch sonotube about 6 feet tall, and an 8 inch sonotube as the port... models pretty well, but you'd definitely need to cross it over to the v3600's pretty low to ensure 1st port resonance isn't an issue...
I'm glad you're sharing my design here, but you really shouldn't make that statement so definitively.

1PR at 48" is 141Hz. With a normal 80Hz 4th-order crossover, the sub is down ~20dB @ 140Hz and 24dB @ 160Hz. Do you really think that there's an audible resonance issue in one case and not the other? If it was, then people with 160Hz 1PR wouldn't be able to cross at 90Hz or higher. I crossed my subs to my old speakers at 100Hz with zero issues whatsoever. There's nothing to be worried about. People have used much lower 1PR without issues.

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Subs: The Two Towers (HT18 32cf 11.5Hz x 2), UM18 4cf x 2, Crowson MAs x 4
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post #8 of 9 Old 09-20-2019, 08:51 AM
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Quote:
Originally Posted by aron7awol View Post
I'm glad you're sharing my design here, but you really shouldn't make that statement so definitively.

1PR at 48" is 141Hz. With a normal 80Hz 4th-order crossover, the sub is down ~20dB @ 140Hz and 24dB @ 160Hz. Do you really think that there's an audible resonance issue in one case and not the other? If it was, then people with 160Hz 1PR wouldn't be able to cross at 90Hz or higher. I crossed my subs to my old speakers at 100Hz with zero issues whatsoever. There's nothing to be worried about. People have used much lower 1PR without issues.
agreed that its down quite a bit... I was thinking more along the lines of you might have 3 sets of speaker contributing enough energy in that range (where the 1st port resonance is) that it could be unpredictable and definitely audible... the 3 speakers being the v3600's, mains, and this new creation. If this new setup is really only needed to hit hard low, then crossing it at say 60 Hz vs. 80 Hz just seemed like it would make things easier is all...

that said, my preference theoretically at least is to try and have the crossover at least one octave below the port resonance. But I've never done any listening tests that could tell me how audible that is, so there's that...

To your point though, I'm guessing most (all?) couldn't hear it, and if you could, probably couldn't tell that's what it was from (port resonance).


Hey, there's always bigger sonotube and SHS-24's sealed...

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post #9 of 9 Old 09-20-2019, 09:15 AM
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Quote:
Originally Posted by jcr159 View Post
agreed that its down quite a bit... I was thinking more along the lines of you might have 3 sets of speaker contributing enough energy in that range (where the 1st port resonance is) that it could be unpredictable and definitely audible... the 3 speakers being the v3600's, mains, and this new creation. If this new setup is really only needed to hit hard low, then crossing it at say 60 Hz vs. 80 Hz just seemed like it would make things easier is all...
Just remember, with any number of subs, it's still down the same 20dB @ 140Hz.

Quote:
Originally Posted by jcr159 View Post
that said, my preference theoretically at least is to try and have the crossover at least one octave below the port resonance. But I've never done any listening tests that could tell me how audible that is, so there's that...
I hear ya, and it's a good rule of thumb, but like most rules of thumb it's not a hard and fast rule, and it's a not a cliff where there's no issue at one octave and an issue as soon as you go barely below one octave.
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Take the Red Pill (BassEQ) BassEQ Demo Clips
Video: Sony 85" X900F @ 80" eyes-to-screen (49.4° viewing angle)
Audio: Denon AVR-X4400H 7.2.4 Atmos
Mains: Fusion-15 LR, Custom Tapered Ported Volt-6 Center, Ported Volt-10 Surrounds, Custom 45°/45° Double-Angled Ported Volt-6 Atmos
Subs: The Two Towers (HT18 32cf 11.5Hz x 2), UM18 4cf x 2, Crowson MAs x 4
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