Help Me Decide Between Two 18” Subs

[stevef22]

Hello, I have a challenging room. The room is very lofty, including an open staircase with no door, bathroom with no door etc. I have Polk R700 speakers at one end with a bed at the other. My plan is to build/buy two matching front ported subs tuned at 27Hz and place them in the corner behind R700s speakers.


My main listening music is 2CH Electronica, Drum bass, Enigma. Movies maybe 20% of listening. I’m targeting good deep bass that you can feel in your chest.


GPT said my Box tune should be 27Hz to avoid any room modes.


What do you know!? I found a MBM (Mid Bass Module) tuned to exactly 27Hz on GSGs website.

MBM-18 Roundover Series Flat Packs (2-PACK)

MartySubs by GSG(TM) offer the best performance at the best price, anywhere. Check out our DIY flat packs as well as our finished enclosures. On sale now.

shop.gsgad.com

My question would be what driver would you recommend for this box? I’m deciding between


Ultimax II.

Dayton UMII18-22 Home Theater Subwoofer Driver

SPECIFICATIONS 18” Nominal Diameter 1,200 Watts Nominal Power Handling (RMS) 2,400 watts Power Handling (max) 3-inch Diameter Voice Coil Woven carbon fiber cone Dual spiders Large aluminum pole cap and shorting ring to minimize distortion Cast Aluminum Basket Ferrite Magnet 1 or 4 Ohms Impedance...

shop.gsgad.com

Lavoce

LaVoce SAF184.03 18

SPECIFICATIONS 3,000 Watts continuous program power capacity (RMS) 100 mm (4-inch) copper voice coil 45 mm peak-to-peak excursion (damage point is even higher) 14.3 mm xmax @ 1/3 gap; 19.3 mm usable excursion @ 2/3 gap Double silicone spider Optimized cooling system Aluminium demodulating ring...

shop.gsgad.com

Resources:



Short 2min video Explainer: Room walkthrough

Conversation with GPT

https://claude.ai/share/7b40c825-827e-4b52-9ec9-82071d14989c

GPT Electronic Music

Target response: 20-25 Hz for full coverage of electronic music

Usable extension: Down to 18-20 Hz if you want to capture everything

Practical consideration: Most home listening happens above 25 Hz, so that's where you want your sub to perform best







Thanks for all the info.

 

[voodooless]

Clearly, the AI has little idea what it is doing. The UM18 isn't exactly made for a reflex enclosure. It's much happier in a closed box. At 6 cuft and 27Hz tuning, you'll get a massive bump in the response at 40 Hz. Probably not what you want!

Just use some proper tooling to simulate the box. WinISD will do the trick just fine

You'll need way more volume and way lower tuning to properly integrate the Dayton woofer, like 14 cuft @18Hz or so:

But a closed box is a much better fit.

As for the room stuff that was mentioned, it's rather contradictory. First, explaining how bad the room modes are, then telling you that they are not really a big deal

 

[DVDdoug]

Yes - It's ALWAYS a good idea to plug the Thiele-Small parameters into speaker design software such as WinISD (FREE). It will help you to choose between a ported or sealed speaker and to optimize box volume, and it will model the performance before you buy or build anything.

You don't NEED to go down to 27Hz to get bass you can feel. Most pro subs used live and in dance clubs are tuned down to around 40Hz. Most are ported. 40Hz is close to the lowest note on a standard electric bass guitar and it's low enough for bass you can feel in your body (if it's loud enough). It's a compromise that allows for high efficiency to fill a large venue with bass you can feel.

Full-size pro studio monitors need to go loud and low so they usually compromise on efficiency. They are large, usually have multiple woofers, and are powered by big amplifiers. They may be ported or sealed.

With a smaller room at home setup you don't usually need as much efficiency or SPL so it's easier to go down to 20Hz or so. But many home subs don't have enough output for that that "slam" that you can feel in your body,

Size is important but a bigger driver isn't always better, especially if box size is limited. With a given-limited box size, a smaller driver can usually go lower, but with a lower maximum SPL. Of course that depends on the particular drivers, and the software can predict how they will perform.

Speaker design involves compromises & trade-offs. This post shows the general trade-offs between sealed & ported speakers. The ported speaker goes lower before dropping-off but it drops-off faster. At some point the curves cross and the sealed speaker puts-out more sound. But that IS a generalization. WinISD (or other design software) will give you more precise information for your particular driver & box.

A lot of active sealed home-theater subs use EQ/DSP and high amplifier power to flatten and extend the low-frequency output beyond what you can get with a ported speaker. That also allows for a smaller box.

If you tune a ported speaker with a small bump in the response you can extend the low frequency cutoff a bit more. And the slight bump may be unnoticeable or even desirable. But EQ/DSP doesn't work as well with ported speakers because the slope is steeper and the driver moves freely at the lower frequencies below cutoff, so you can end-up with the woofer flopping around and maybe causing distortion without much output.

GPT said my Box tune should be 27Hz to avoid any room modes.

That's probably nonsense... You likely have a few room modes higher than that unless you have a VERY large room. And by "large" I mean like a theater or concert hall. There is room simulation software but I don't have a link. A lot of people with home studios use small monitors, I guess with the idea that no bass is better than bad bass, but IMO that's not the best solution.

 

[stevef22]

Thanks for modeling this Voodoo. I thought it was too good to be true.

However a closed box with the Ultimax II... I can build! Thus saving more $$

Im a novice at this stuff so please bear with me. I modeled a closed box on RF website. See attached pictures.

This would be 12CU feet. Is this too much?


(I prefer a taller, rectangle style sub box)


Thank you

 

[stevef22]

Yes - It's ALWAYS a good idea to plug the Thiele-Small parameters into speaker design software such as WinISD (FREE). It will help you to choose between a ported or sealed speaker and to optimize box volume, and it will model the performance before you buy or build anything.

You don't NEED to go down to 27Hz to get bass you can feel. Most pro subs used live and in dance clubs are tuned down to around 40Hz. Most are ported. 40Hz is close to the lowest note on a standard electric bass guitar and it's low enough for bass you can feel in your body (if it's loud enough). It's a compromise that allows for high efficiency to fill a large venue with bass you can feel.

Full-size pro studio monitors need to go loud and low so they usually compromise on efficiency. They are large, usually have multiple woofers, and are powered by big amplifiers. They may be ported or sealed.

With a smaller room at home setup you don't usually need as much efficiency or SPL so it's easier to go down to 20Hz or so. But many home subs don't have enough output for that that "slam" that you can feel in your body,

Size is important but a bigger driver isn't always better, especially if box size is limited. With a given-limited box size, a smaller driver can usually go lower, but with a lower maximum SPL. Of course that depends on the particular drivers, and the software can predict how they will perform.

Speaker design involves compromises & trade-offs. This post shows the general trade-offs between sealed & ported speakers. The ported speaker goes lower before dropping-off but it drops-off faster. At some point the curves cross and the sealed speaker puts-out more sound. But that IS a generalization. WinISD (or other design software) will give you more precise information for your particular driver & box.

A lot of active sealed home-theater subs use EQ/DSP and high amplifier power to flatten and extend the low-frequency output beyond what you can get with a ported speaker. That also allows for a smaller box.

If you tune a ported speaker with a small bump in the response you can extend the low frequency cutoff a bit more. And the slight bump may be unnoticeable or even desirable. But EQ/DSP doesn't work as well with ported speakers because the slope is steeper and the driver moves freely at the lower frequencies below cutoff, so you can end-up with the woofer flopping around and maybe causing distortion without much output.


That's probably nonsense... You likely have a few room modes higher than that unless you have a VERY large room. And by "large" I mean like a theater or concert hall. There is room simulation software but I don't have a link. A lot of people with home studios use small monitors, I guess with the idea that no bass is better than bad bass, but IMO that's not the best solution.

Thank you very much for the information DVDdoug. I will download WinISD and give it a try.

From my previous post to Voodoo. It looks like I would be fine with an Ultimax II inside a sealed box. Im just trying to figure out best CU feet for my room. If I have two of these corner loaded.

However the Lavoce 18" has much less xmax but better punching power.

 

[aschen]

I have a single original ultimax in the original PE sealed flat pack (4cuft I think). It is in a space much larger than what you have shown.

I am not the best person to recommend an optimal box, but the output and headroom for EQ is PLENTY with appropriate (read tons) of power. A pair even sealed in a lowish volume space will have have more output than is pleasant.

 

[DVDdoug]

Im just trying to figure out best CU feet for my room.

The ideal sealed or ported volume depends on the driver, not the room, and the best design (or best compromise) will be the best in any room. Yes, the room affects bass but you want to start with a good speaker.

 

[stevef22]

The ideal sealed or ported volume depends on the driver, not the room, and the best design (or best compromise) will be the best in any room. Yes, the room affects bass but you want to start with a good speaker.

Good points, thank you

 

[OldHvyMec]

Take your pick, a 4ft enclosure with 2 15PRs, a single 18" active, or dual 18" High excursion passive radiators will work and easily go down to 20-25.

It's an absolute myth that a single passive radiator won't work. If it has at least 1.5-2.0 times the excursion of the active.
I've used a single PR of the same size many times with the excursion 3/4 the sub, and only after I tried did I blow the passive. I had to turn it up, and then for 30+ minutes.
I went to a single 12-HE/HO PR for a 12 Ultimax I in a 2.5cf enclosure. 22Hz all day long.

Slot-loaded enclosures are nice when the slot has at least a matched size PR. It's a lot easier to tune as low as you want just by adding a mass.

45 years of building Bass columns and subs. You just have to know the drivers. UM12, 15 and 18s. I can go lower with the UM15 I/II, a 4ft enclosure, and a single 18" passive. 15-18 Hz is pretty easy, and 2 will fill a 2400CF room (15X20X8). With just a little more effort, you can get a pretty smooth response at the seated position.

BTW, a 4cf blank box from PE is $209.00, and shipping is no extra charge. I've used 50+ of the 3 and 4cf boxes. Easy, well-built, and usually available.
Marty's are HEAVY and purpose-built for being extra tough. I can't figure out an environment they would be purpose-built for.
A club, a workshop, or they have enclosures for HT hidden use. But believe this, the Marty's are HEAVY enclosures when assembled, stuffed, feet/casters, and driver loaded.

My favorite for coverage is dual UM12s and a single 18" passive in a 4 cf box. I place the side with no drivers towards the wall, the two actives parallel to the wall and the passive into the room. 2 DOS/PRs WORK pretty friggin good", considering what it cost and haw they work. My personal subs are 15" active 18" PR in 4cff boxes. It's a 16X20X8ft room. If the room is sealed and you turn them up. TAPE the windows!

Regards

 

[stevef22]

Take your pick, a 4ft enclosure with 2 15PRs, a single 18" active, or dual 18" High excursion passive radiators will work and easily go down to 20-25.

It's an absolute myth that a single passive radiator won't work. If it has at least 1.5-2.0 times the excursion of the active.
I've used a single PR of the same size many times with the excursion 3/4 the sub, and only after I tried did I blow the passive. I had to turn it up, and then for 30+ minutes.
I went to a single 12-HE/HO PR for a 12 Ultimax I in a 2.5cf enclosure. 22Hz all day long.

Slot-loaded enclosures are nice when the slot has at least a matched size PR. It's a lot easier to tune as low as you want just by adding a mass.

45 years of building Bass columns and subs. You just have to know the drivers. UM12, 15 and 18s. I can go lower with the UM15 I/II, a 4ft enclosure, and a single 18" passive. 15-18 Hz is pretty easy, and 2 will fill a 2400CF room (15X20X8). With just a little more effort, you can get a pretty smooth response at the seated position.

BTW, a 4cf blank box from PE is $209.00, and shipping is no extra charge. I've used 50+ of the 3 and 4cf boxes. Easy, well-built, and usually available.
Marty's are HEAVY and purpose-built for being extra tough. I can't figure out an environment they would be purpose-built for.
A club, a workshop, or they have enclosures for HT hidden use. But believe this, the Marty's are HEAVY enclosures when assembled, stuffed, feet/casters, and driver loaded.

My favorite for coverage is dual UM12s and a single 18" passive in a 4 cf box. I place the side with no drivers towards the wall, the two actives parallel to the wall and the passive into the room. 2 DOS/PRs WORK pretty friggin good", considering what it cost and haw they work. My personal subs are 15" active 18" PR in 4cff boxes. It's a 16X20X8ft room. If the room is sealed and you turn them up. TAPE the windows!

Regards

Wow, ok so now I’m really confused. But still learning

Can you help model me a cabinet for the

LaVoce SAF184.03 18" Professional Subwoofer

https://www.lavocespeakers.com/lavoce/assets/datasheets/1508341344_LAVOCE_SAF184.03_18in_SUBWOOFER_A.b.pdf

For my space here

Sealed preferably. Tuned to accommodate the wide open leaky 30ft long room. Listening music is electronic, drum & bass, Enigma


I would like to make the sub like a tall rectangle. So 60 in tall. 22 in wide. Depth ? unknown

 

[SIY]

Wow, ok so now I’m really confused. But still learning

Can you help model me a cabinet for the

LaVoce SAF184.03 18" Professional Subwoofer

https://www.lavocespeakers.com/lavoce/assets/datasheets/1508341344_LAVOCE_SAF184.03_18in_SUBWOOFER_A.b.pdf

For my space here

Sealed preferably. Tuned to accommodate the wide open leaky 30ft long room. Listening music is electronic, drum & bass, Enigma


I would like to make the sub like a tall rectangle. So 60 in tall. 22 in wide. Depth ? unknown

Are you open to using electronic EQ? That driver in a sealed box will end up giving you a 45-50Hz rolloff, but you absolutely can EQ it flat to under 30Hz. The Linkwitz Transform is your (potential) friend.

 

[stevef22]

Thanks, yes! I was already planning on hooking the two subs to a mini dsp and eq them.

 

[levimax]

I just finished building 2 GSG 18" "Full Monty" subs with the LaVoce drivers.

A few thoughts.

GSG kits are great. Very well braced, precision cut, good instructions.

I am running my "Full Marty's" sealed and prefer them that way for music. If I was going to do it over again I would start out with large sealed and well braced enclosures with a Qtc 0.707. Old school and "too big" according to some but easy, reliable, and great time domain performance which is the downfall of many "modern" subs.... DSP makes advertised specs look good at the expense of group delay / transient response.

LaVoce drivers are great, much higher mid-bass output which can be "shaved off" if needed. Due to lower X-max and higher efficiency they have less distortion but still plenty of LF extension in the right enclosure, probably more than the Daytons at reasonable distortion levels. You may find that big subs not only fill in the LF but they also can put out high SPL ~100 Hz which is where the majority of the energy in most music lies and many main speakers start to distort or compress more than you might think if you are trying to play loud. For dedicated sealed subs there are probably better drivers but I would stick with the "pro-audio" drivers.

Not sure what you are planning for amplification but there is someone on ebay selling brand new Crown XLC21300 (1,300 watt per channel 4 ohms no DSP) very cheap. I was worried but bought one and it really is brand new in the box and is prefect for this application. Since it is a Professional Cinema amp the hook up is not standard but it is not hard. https://www.ebay.com/itm/364056130409?_skw=crown+XLC21300&itmmeta=01JZR76WY7VV23PS8N0TJWA3FG&hash=item54c36fb369:g:SFAAAOSw2g9jBnxP&itmprp=enc:AQAKAAAA8FkggFvd1GGDu0w3yXCmi1eZNESBJrU2qSfHodm7lZJmecXZSfxEzqgL+yFX7tx9dvnGCxoEX/k7CPofxtqQsbmPVjXuPHWLAwJiZYpABPhwsp7QuTgw47jFwvy6+thZohDoG7i+1NubTIgpLz2OSMSXaCu7N9WvW5rI5l4C1TsSEBeLUF28QdKKJpYe4BVO+nItFiigi3Qk5gHm9SeP0kl36a8+L7heC9D+yw6GvfPL198s3M+IFr/WmG/PQMoDBrbR4B8mDZoUK2KeeRLOXCK8zwR8IjZFQYyO1/5/OicEIkXjxcavKf8BIcbe6Fasqw==|tkp:Bk9SR5bPm4f-ZQ

Good luck and have fun

 

[DVDdoug]

Sealed preferably.

Why did you decide that? Personally, I wouldn't make that decision without modeling with software first. Some speakers work better in sealed cabinets and some better in ported cabinets. And if you have size constraints (which I think you don't) the size of the box can also influence whether a ported or sealed cabinet performs better.

Tuned to accommodate the wide open leaky 30ft long room.

Again, you don't normally "tune" the speaker for the room. You build (or buy) the best speaker you can and then you can optionally use EQ and/or acoustic treatment to deal with acoustic problems. ("Regular" acoustic panels don't help with bass. You need bass traps or other methods to fix bass problems.)

"Leaky" is usually good! The problem is usually with reflected bass and holes in the room are very effective "bass traps". Minimizing the reflections reduces standing waves, smoothing both the dips and the bumps. The bumps (where the direct and reflected waves add together) can usually be knocked-down with EQ but the dips (where the direct and reflected soundwaves subtract & cancel) can't really be fixed with EQ because it takes "infinite power" to overcome cancelation.

Bigger rooms also tend to be better.

I would like to make the sub like a tall rectangle. So 60 in tall. 22 in wide. Depth ? unknown

The main thing is generally the internal cabinet volume, not the shape. With a ported design, cabinet volume, port volume, and port length/volume interact to affect the tuning.

Can you help model me a cabinet for the

You can enter the parameters into WinISD just as easily as me, and I'm lazy! Plus, if you do it yourself you can try some changes (virtually), including comparing sealed & ported, to see what happens.

 

[SIY]

Thanks, yes! I was already planning on hooking the two subs to a mini dsp and eq them.

OK, with the proviso that the Xmax of those drivers isn't huge (don't do this in a ballroom and don't try for a response lower than about 25Hz or so), design the cabinet volume to give you a Qtc of 0.7, then use the Linkwitz Transform stuff from miniDSP to put in EQ coefficients.

 

[voodooless]

LaVoce drivers are great, much higher mid-bass output which can be "shaved off" if needed. Due to lower X-max and higher efficiency they have less distortion but still plenty of LF extension in the right enclosure, probably more than the Daytons at reasonable distortion levels.

I'd say, citation needed. Lower Xmax and higher efficiency == lower distortion, does not follow. The Ultimax is built for deep LF extension at low distortion in a relatively small box (just bring enough power). They each have their strengths and weaknesses. Below 30 Hz, the Ultimax will most certainly perform better. If the 10" version (or even the 8" version)is anything to go by, distortion should be extraordinarily good. If that's what you're after, then that could be a reason to pick it. If not, it gets much more complicated.

You may find that big subs not only fill in the LF but they also can put out high SPL ~100 Hz which is where the majority of the energy in most music lies and many main speakers start to distort or compress more than you might think if you are trying to play loud. For dedicated sealed subs there are probably better drivers but I would stick with the "pro-audio" drivers.

This is the issue with these things, isn't it: they excel basically from 50 to 150 Hz, but in a home environment, usually the crossover to the sub is around 80 Hz. So, actually, much of what they can do is lost in such a setup.

If you put the subs close enough to the mains, and cross much higher (150Hz or so), I would say the LaVoce would make a lot more sense.

In the end, both can make excellent subs, it just depends on what you want them to do, and how much real estate you are willing to spend on it (in terms of enclosure size, placement, amplifier power, etc).

 

[MKR]

Just go with the Devastator and be done with it … sheesh what a beast …

Devastator MkII 21-inch Ported Horn Home Theater Finished Subs (Powered and Passive models, 19Hz tuning) FREE SHIPPING!!!

GSG(TM) subs offer the best performance at the best price, anywhere. Check out our DIY flat packs as well as our finished enclosures. On sale now.

shop.gsgad.com

 

[levimax]

I'd say, citation needed.

From GSG web site FAQ:

How "low" will a driver go?
From time to time we get asked about drivers and cabinets. Frequently, folks see a particular driver specification (such as the driver free-air resonance (Fs), a claim by the manufacturer that the driver is good for a particular range, such as 20-150Hz, or that a driver has a particular -6dB point such as 28Hz) and are led to believe that these numbers determine how low a subwoofer can play in a particular enclosure. This is NOT THE CASE!

When a driver is placed in a cabinet, the two form a *system*. As such, not knowing anything about the cabinet that a driver will be placed in tells us nothing about how the driver is capable of performing.

For the first example, we will use a Dayton UM-18 driver, which is a long-throw, low efficiency (88dB/1w1m), subwoofer with a ton of excursion capability (usable excursion of over 30 mm). It has a free-air resonance (Fs) of 21 Hz. For the second example, we will use a LaVoce SAF184.03 driver, which is a hybrid driver that has medium-high efficiency (95 dB/1w1m) and medium-high excursion capability (usable excursion of approximately 19 mm). It has a free-air resonance (Fs) of 29 Hz.

So which driver “will play lower”, the 21 Hz driver or the 29 Hz driver?

It turns out that when these drivers are placed in a Mini-Marty subwoofer cabinet (which is approximately 7.5 cubic feet of internal volume and tuned to 18Hz), both drivers will have the same low end extension! The picture shows output at a nominal 1,100 watts of power, just for comparison. (Note that frequencies below approximately 16 Hz will be filtered out by the protective high pass.)

At 1,100 watts of power, neither driver exceeds its excursion capability. The LaVoce, however, provides quite a bit more output in the mid-bass region (60-120 Hz). When EQ’d to have the same response as the Dayton, the LaVoce will require quite a bit less power to produce the same amount of mid-bass output. This in turn gives it a subjectively harder-hitting mid-bass.

In summation, be careful when reading about driver parameters, manufacturers’ claims, or folks on the internet stating “how low a driver will go”. In order to know for sure, one has to model it up using the Thiele/Small parameters and for the most part, the enclosure itself is the dominating factor in factor in determining how low a driver will play. Of course, how much usable excursion a driver has is important when selecting an enclosure and an amplifier, as that will ultimately dictate output limits in many cases.

 

[SIY]

Just go with the Devastator

Devastator? Has Drew A. Kaplan been resurrected?

 

[MKR]

Devastator? Has Drew A. Kaplan been resurrected?

Sorry, not following the reference