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Dual Subwoofers for Large Room

AaronDC

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Hi.

My listening room is a very large space in our great room. It's a converted church 40' x 19' x 15' high at the peak of the vaulted ceiling. I estimate approximately 8,000 cu ft. I'm making some changes and subwoofers will have to be part of it. I have one Hsu VTF-2 MK4. Right now I'm running Klipsch Cornwalls in the room corners. They have ported 15" subs and I don't use my sub with them. In fact I had to EQ the room boom down with them. I listen to all kinds of music. We don't do home theather, so I don't need or want room shaking bass. I want subtle articulate musical bass. Anyway for 150Hz and above, I'm probably going to go exotic: Tectonic DML500s which are pro-audio speakers and will need help below 150Hz or so. I think I could really benefit from two subs to have more even bass throughout the room. I've been looking at the incredible spreadsheet by @sweetchaos. Our room is definitely in the "Extreme" category. So, on a value basis, I'm looking at Hsu or SVS. TBH I'm not wild about how they look. WAF has me considering other options. I could DIY them and get a custom walnut veneer or something. Anyhoo, I need to decide on sizing/power/configuration for two versus one. The single-sub suggestions I get from the spreadsheet Hsu sub is the VTF-15H MK2 and the SVS SB-3000. Budget is about $1,500, so used is fine and so is DIY. So... here's the question: Can I scale down the size of my sub if I buy two? How does that work? What do you suggest?

Thanks!
Aaron
 

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alex-z

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Single subwoofer in a space like that is going to do you zero favours. Too many room mode problems. Especially if you don't have absolutely perfect subwoofer placement.

Your best bet is 2, or ideally 4 sealed subwoofers spread throughout the room.

Ultimax 10" for example hits .707 QTC in an .85ft cabinet, giving you an F3 point of 39Hz, and F10 of 23Hz.

https://www.parts-express.com/Dayton-Audio-UM10-22-10-Ultimax-DVC-Subwoofer-2-ohms-Per-Co-295-510

https://www.minidsp.com/products/minidsp-in-a-box/minidsp-2x4-hd

https://www.parts-express.com/Dayton-Audio-SPA250-250-Watt-Subwoofer-Amplifier-300-803

$700 in drivers, $300 for EQ, $600 in amps.

You will have a lot of headroom to EQ. At a 3 metre listening distance, each sub can output roughly 92dB on 250 watts. So 98dB with 4 of them. Plus the room gain, which will add at least 6dB.

Under 10ms of group delay all the way to 10Hz, and there should be no problems with thermal compression at that power level.

The simplest approach is put 1 sub in each corner.

https://www.harman.com/documents/multsubs_0.pdf
 
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AaronDC

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Thanks for your help. WAF requirements: I appreciate the recommendation for 4, but I think 2 is the maximum. I have a MiniDSP 2x4HD. So, with that in mind... What's the suggestion?
 

raistlin65

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I have Power Sound Audio V1510 and V1512 subwoofers in my living room which is part of an open floor plan space of almost 6000 cubic feet. After my experience trying smaller less powerful subwoofers, with your size space, I think you would need two subs at least that powerful if you're looking for good bass.
 

alex-z

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Thanks for your help. WAF requirements: I appreciate the recommendation for 4, but I think 2 is the maximum. I have a MiniDSP 2x4HD. So, with that in mind... What's the suggestion?

In that case maybe go with dual Ultimax 15".

https://www.parts-express.com/Dayton-Audio-UM15-22-15-Ultimax-DVC-Subwoofer-2-ohms-Per-Co-295-514

4ft sealed cabinet yields F3 at 31Hz, F10 at 19Hz. They are also quite a bit more efficient. 250 watts at 3 metres translates to 98dB output for a single sub, +3dB for the second sub, and +6dB for the room gain.

The Ultimax 12" is out of stock right now, but would be a good middle ground choice if the wife turns down the idea of 4ft subwoofer cabinets.
 

Bear123

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I would suggest a good pair of pro audio drivers if going DIY. Definitely DO NOT use small, cheap, low sensitivity Dayton Ultimax drivers; that would be a horrible solution. These are high excursion home theater subs. Try a good pair of pro audio drivers such as:
B&C 15DS115 for a 15" woofer if you want to keep the cabs small.
Lavoce Neo 15 for a very good quality but cheaper option.
LaVoce Neo 18 This is what I'd get for: 1) on a budget, 2) DIY, 3) huge room 4) extraordinary sound quality and capability on music.

Honestly, even a pair of cheap bargain budget Dayton PA-460 drivers would put out a ton of very impressive, impactful music bass and would walk all over the Ultimax for a music only setup. Check out this link for a ported DIY build using this driver:
PA 460 DIY build. I used this driver(and still have it boxed up) in a 4ft^3 sealed cab and it walked all over much much much more expensive high excursion 18's for music.

For amp, on a budget, Behringer NX6000. Don't need the "d" version(DSP) since you have miniDSP. Cost difference might not be huge and the included DSP is extremely versatile so maybe get it just in case. The 3000 version will probably drive any of these pro drivers to higher SPL than you could want or need, which is of course just right.

If you want a small, extremely capable sub for music without DIY, I'd look at PSA's S1512. It uses the B&C DS115 driver I linked above(perhaps with some proprietary tweaks, not sure). I demo'd a pair of these and was *VERY* impressed with their capability on music, and this was coming from a pair of BMS18n862....which is one of the best pro audio 18" drivers in the world regardless of cost. I wanted to downsize a bit from the 18's and those small PSA 15's were shockingly capable.
 
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alex-z

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I would suggest a good pair of pro audio drivers if going DIY. Definitely DO NOT use small, cheap, low sensitivity Dayton Ultimax drivers; that would be a horrible solution. These are high excursion home theater subs.

Lavoce 15 vs UM15 transfer function.pngLavoce 15 vs UM15 group delay.pngLavoce 15 vs UM15 SPL.png

UM15 in the 4ft sealed cabinet, vs the Lavoce Neo 15 in a 3.8ft ported cabinet (36Hz port tune), for optimal F3 point. Both drivers with a 20Hz high-pass filter. Neo 15 set to 180 watts, UM15 set to 770 watts. Both at the limits of their respective xmax.

The UM15 plays flatter, with less group delay, comparable SPL, and no port noise, yet is "horrible"?

These drivers are meant for 2 entirely different use cases, and dismissing the UM15 just because you see home theatre enthuisiasts use it is highly biased.
 

Bear123

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Yes, in real life, outside of simulations, pro drivers will do 40Hz+ better than high excursion low sensitivity deep bass drivers.

Side by side in the same room, an $89 Dayton PA-460 ran circles around an HST-18 on music. It also ran circles around the SI-HT18 which performs very comparably to the UM18. BMS18n862 was also vastly superior to all three of these drivers other than very low bass to the HST-18(a 70 lb driver with 35mm Xmax). The B&C 15DS115 kept up surprisingly well to the BMS18's on music.

Ultimax are very good, reasonably price, low sensitivity, high excursion deep bass subwoofers. They won't perform as well as pro drivers with music, which is the OP's use case. He is of course free to follow your advice if he thinks your plan is the best for his situation. If not being used for movies, I don't think Ultimax are remotely close to an optimal choice.
 
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AaronDC

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Thanks. Lots more to research here. Yeah. I'm not looking for digging super deep on low frequencies. I want delicate sophistication and accurate fast kick. BTW, I sat on my couch and cranked my Cornwalls as loud as I could tolerate them and my UMIK-1 was reading 95db sustained playing AC/DC Shoot to Thrill. I'm sure there were peaks beyond that, but that's where I stop.

I was getting sold on the Rythmik direct servo technology. Makes a lot of sense and there are some DIY options as well.
 
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Chrispy

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I wouldn't consider your Klipsch woofers "subs" even corner loaded. That's a big room for a single 12" tho.
 

Bear123

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Thanks. Lots more to research here. Yeah. I'm not looking for digging super deep on low frequencies. I want delicate sophistication and accurate fast kick.

I was getting sold on the Rythmik direct servo technology. Makes a lot of sense and there are some DIY options as well.
I like Rythmik alot. I currently own a pair of Rythmik FV15HP. In fact, I demo'd Rythmik FV15HP and PSA S1512 side by side after I got rid of my DIY pro audio 18's. 18's are big in every direction....no chance for a narrow baffle which is part of the reason I moved down to 15's.

FV15HP were much stronger below 30 Hz(obviously....large ported vs small sealed) and since I'm mixed movies/music, its what I kept. However, I do feel the S1512 had a more concussive, impactful mid bass presentation. Having heard many subs side by side, I firmly believe pro drivers do something on music that higher excursion low sensitivity drivers just can't do as well, regardless of specs on paper. HST-18($700 70 lb 35mm Xmax) burst output on data-bass would leave you to believe those drivers will provide all the soul crushing chest compressing mid bass kick one could imagine.....fact is, an $89 pro audio driver ran circles around it in real life, and with very little power.

Whether it was the Dayton PA-460, BMS pro drivers, or the B&C 15DS115 I heard in the PSA S1512, pro driver are designed from the ground up to excel on music bass above 40 Hz, and yes, this is at some or A LOT of expense in low bass. You can't be the best at both.

My wife does prefer the Rythmik's to the PSA, and this is in large part due to the concussive mid bass impact of the pro drivers. She subjectively refers to them as "too sharp"...she can't tolerate them at demo levels.

I don't think your going to get a pair of Rythmik subs adequate for that room within your budget. I was thinking E15HP2 for you but one eats up your budget.

Were I in your shoes and you decide to go ID rather than DIY, I'd seriously consider ordering one E15HP2 and an S1512 and demo them side by side for a couple weeks. Keep your fav. and order another :D
 

Chrispy

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I like Rythmik alot. I currently own a pair of Rythmik FV15HP. In fact, I demo'd Rythmik FV15HP and PSA S1512 side by side after I got rid of my DIY pro audio 18's. 18's are big in every direction....no chance for a narrow baffle which is part of the reason I moved down to 15's.

FV15HP were much stronger below 30 Hz(obviously....large ported vs small sealed) and since I'm mixed movies/music, its what I kept. However, I do feel the S1512 had a more concussive, impactful mid bass presentation. Having heard many subs side by side, I firmly believe pro drivers do something on music that higher excursion low sensitivity drivers just can't do as well, regardless of specs on paper. HST-18($700 70 lb 35mm Xmax) burst output on data-bass would leave you to believe those drivers will provide all the soul crushing chest compressing mid bass kick one could imagine.....fact is, an $89 pro audio driver ran circles around it in real life, and with very little power.

Whether it was the Dayton PA-460, BMS pro drivers, or the B&C 15DS115 I heard in the PSA S1512, pro driver are designed from the ground up to excel on music bass above 40 Hz, and yes, this is at some or A LOT of expense in low bass. You can't be the best at both.

My wife does prefer the Rythmik's to the PSA, and this is in large part due to the concussive mid bass impact of the pro drivers. She subjectively refers to them as "too sharp"...she can't tolerate them at demo levels.

I don't think your going to get a pair of Rythmik subs adequate for that room within your budget. I was thinking E15HP2 for you but one eats up your budget.

Were I in your shoes and you decide to go ID rather than DIY, I'd seriously consider ordering one E15HP2 and an S1512 and demo them side by side for a couple weeks. Keep your fav. and order another :D

Can you correlate measurements to that perception of different capabilities, assuming everything else was equal? Is it just preference rather than reference?
 

Bear123

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Can you correlate measurements to that perception of different capabilities, assuming everything else was equal? Is it just preference rather than reference?
OK so this is where it gets into I guess you could say theory a little bit.

I struggled to understand why a $700 driver that was objectively tested on Data-Bass to produce max burst SPL of 122+ dB 2m RMS 40Hz+, produced a *drastically* less impactful experience on music compared to a $89 Dayton driver. Part of the answer is that Ricci is bursting over 5,000 watts into the driver to hit those peaks, and I had at best about 1800 watts on my driver. The other thing though is that I think these heavy, high excursion drivers not only need A LOT of power up top, but you then run into a lot of compression so you don't get accurate playback of transient peaks. The very high sensitivity pro drivers have different impedance curves and require a very small fraction of the power to hit those same peaks so even though the big heavy driver hits big numbers on paper...during playback the pro drivers are just more lifelike and concussive. You can literally feel the kick in your chest that you don't get with the high excursion monsters.

Here's an example of two of the drivers I've had:
Screen Shot 2021-05-05 at 9.07.47 PM.png

This isn't max output of either driver, just max output in the lower frequencies with a full range sweep at that output level. What's interesting here is that this is about 2500 watts into the HST-18, and about 1,000 watts into the BMS, yet it still makes 4-6 dB more SPL up top with less than half the power. Although I can't pinpoint for 100% certainty what exact parameter or combination of parameters results in the drastic subjective difference, I think it must be some combination of sensitivity, light weight cone, impedance, and lack of compression that allows the pro drivers to track transient mid bass peaks more accurately. Like the feeling you get when your IN the room with a drum set.
 

jeffmackwood

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Hi.

My listening room is a very large space in our great room. It's a converted church 40' x 19' x 15' high at the peak of the vaulted ceiling. I estimate approximately 8,000 cu ft. I'm making some changes and subwoofers will have to be part of it. I have one Hsu VTF-2 MK4. Right now I'm running Klipsch Cornwalls in the room corners. They have ported 15" subs and I don't use my sub with them. In fact I had to EQ the room boom down with them. I listen to all kinds of music. We don't do home theather, so I don't need or want room shaking bass. I want subtle articulate musical bass. Anyway for 150Hz and above, I'm probably going to go exotic: Tectonic DML500s which are pro-audio speakers and will need help below 150Hz or so. I think I could really benefit from two subs to have more even bass throughout the room. I've been looking at the incredible spreadsheet by @sweetchaos. Our room is definitely in the "Extreme" category. So, on a value basis, I'm looking at Hsu or SVS. TBH I'm not wild about how they look. WAF has me considering other options. I could DIY them and get a custom walnut veneer or something. Anyhoo, I need to decide on sizing/power/configuration for two versus one. The single-sub suggestions I get from the spreadsheet Hsu sub is the VTF-15H MK2 and the SVS SB-3000. Budget is about $1,500, so used is fine and so is DIY. So... here's the question: Can I scale down the size of my sub if I buy two? How does that work? What do you suggest?

Thanks!
Aaron
Hmmm...

Plants on top of speakers. Can you say "disaster waiting to happen?"

To your basic question: get two subs.

Get the best you can afford for the money you can spend.

If buying new, among other brands, I'd be contacting both PSA and SVS and talking to their very knowledgeable sales/support folks. At least see what they suggest.

If buying used, there's lots to choose from. I've found some great deals on used SVS over the last few years. For space and WAF reasons you might consider something like the SVS PC13-Ultra. Running it in sealed mode (ie. three port plugs) might give you the sound you're looking for. But as I said, there's dozens and dozen and dozens of possibilities.

If going DIY... sorry, can't help you there. My sub-building days ended in the early '80s!

Good luck!

Jeff
 
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