Hello from Ohio!

[kenzo]

Hello all,

After months and months of despondent FB Marketplace research I recently got it into my head to build my own subwoofers. I was initially attracted to Scott Hinson's double 18" design, but this would be my first time building speakers (I do have experience with carpentry) and BFM providing very comprehensive details on every aspect down to DSP makes me more comfortable for a first foray. They're largely for personal enjoyment, but I do host quite a lot, loan out sound for events, etc. I would be mostly listening to techno/idm/dub/reggae so the tubas make more sense for me, I would really like all the extension I can get.

My questions are mostly around determining correct model, number, etc

1 - I'm leaning toward the T30, but am not quite sure what the difference would be from the T45. From what I've read they are functionally identical besides form factor, but does the fact the T45 is "end firing" change how they might be assembled or resonate together?

2 - How many would I need to build for clean extension to, say, 30 Hz? Would two suffice, or should I build 4 to have some extra backup when necessary? My focus is really on extension and sound quality, maximizing SPL is cool and all but not my main concern.

3 - If anyone has actually heard all of these, are you able to explain the different goals/subjective attributes of reflex designs vs paraflex vs tapped horn vs folded horn? I believe both the tubas and titans use a folded horn, and most clubs are using reflex, but tapped horn and paraflex keep coming up. I would just like to understand where these designs sit on the compromise/advantage matrix.

Thank you in advance, I've already learned a lot just lurking!

[Bruce Weldy]

Tubas are where you want to be for 30hz. T30s/45s/60s

The question is - where will you be using them? In your house? Outside? How big of an area?

[kenzo]

All of the above ^^. I can't imagine I'll ever need more than 4, even outside, unless I start getting into mini-festival territory? Probably max 200/300. I'm curious as to how many are needed for consistent extension that low, though. I think I could get by with 2 for audiences of that size, but will sound quality appreciably increase if I do 4?

[Bill Fitzmaurice]

What genres will you be playing? Most users who think they need 30 Hz don't.

[kenzo]

Dub, dub techno, roots, jungle, drumnbass. For personal listening there are artists that use pronounced sub-bass I would like to be able to reproduce better - Autechre, especially their live sets, Bull of Heaven, Basic Channel, Vladislav Delay. The tuba seems to outpace the titan quite handily around and below 30 Hz, if the lower efficiency can be compensated for by building wide cabinets, using higher watt drivers, etc. that seems like a good fit.

[Tom Smit]

kenzo, welcome to the forum!

[Seth]

Hey kenzo, welcome. I'm Seth. It's good to have you here! You're asking really good questions and it seems you have relatively reasonable expectations.

It sounds as though you may have read the placement sticky already. But if you haven't, here it is: Rules for subwoofer placement and stacking

I have a rule of thumb that I follow when helping people choose a cab... If it's going to be used outside more than once in a blue moon that falls on a Tuesday, Titan is the only logical choice. Not to say Tuba's wouldn't work. I'll explain.

30Hz outdoors is doable with one T30/T45 (although one cab is technically supposed to be high-passed at 35Hz, it's rhetorical) if you're standing right next to it and you're in a setting without a lot of ambient noise pollution. But, to get USABLE and impactful 30hz outdoors for anything more than an undersized suburban backyard get-together, you're looking for 8-16 T30/T45's.

Here's the first reason why it will take so many, Equal Loudness Contours. In a nutshell, the lower the frequency, the less sensitive your ears are to hearing. For 30Hz to "sound" as loud as 60Hz, it needs to actually measure an SPL of at least 10dB higher. Once properly EQ'd, 30Hz will probably measure about 20dB hotter than the frequencies produced by the mains/tops to sound the way you'd expect it to sound in your ears.

The second reason, which kinda compounds the first reason is; for all sub cabinet designs that I'm aware of, the sensitivity is lowest at the bottom end of it's usable frequency range.



Looking at the response of the 30" wide T30 (BTW, always build cabs to their max width unless it would make them impossible to deploy, transport, or stow within your specific set of circumstances and requirements)... anyway, looking at the chart this cab has a sensitivity at 30Hz of 90dB, measured at one Meter with an input of 2.83 volts (one watt, based on the 8Ω nominal impedance of the driver).

Every doubling of distance comes with a 6dB drop in SPL.
Every doubling of cab count comes with an increase of 6dB SPL.
Every doubling of watts is an increase of 3dB SPL.
Example:

• 1 watt is the starting point, double it to 2 is +3dB

• 100 watts is +20dB, doubling that to 200 watts is +3dB or +23dB total gain

• 1000 watts is +30dB and doubling that to 2000 watts is +3dB or +33dB total gain

Let's say you're standing 8 Meters (about 26 feet) in front of your speakers and the SPL of your mains/tops is a reasonable 100dB. Let's calculate what it would take for the bottom end to reach a level that properly represents and faithfully reproduces the desired response curve. So we're looking for 120dB at 30hz, at 8 Meters/26 feet.

First, I'm going to add the gain from applying the maximum allowed input voltage of 45 volts. I'm not going to go into the math, but the difference between 2.83 and 45 volts is 24dB. Adding that to the cab's 30Hz sensitivity of 90dB gives us the maximum 30Hz SPL one cab is capable of producing if measured 1 Meter from the mouth of the sub, 114dB.

Now let's adjust for our listening position, -6dB for every doubling of distance. We're 114 at 1 Meter, 108dB at 2 meters, 102dB at 4 Meters, and finally 96dB at our 8 Meter/26 foot listening position.

Need 120dB and we're at 96dB, short 24dB of where we want to be. So let's double the cab count until we get there, +6dB for every doubling of cab count. 1 cab 96dB, 2 cabs 102dB, 4 cabs 108dB, 8 cabs 114dB... Still not there. For simplicity I'm ignoring some of the benefits that occur with larger stacks, but 16 cabs to get 120dB at 30Hz at a distance of only 26 feet. And they're full out on 4000 watts combined power. Wide open, on the limiter, giv'n 'er all she's got captain!

The same goes for any other speaker design. Don't be fooled by marketing hype. Use the response curve for any cab and run the numbers like I did here and you'll see, it just takes a butt load of cabs to hit 30Hz outdoors.

Indoors, we have boundaries we can rely on to help out (covered in the placement link above) and 4 cabs would get you some really solid bottom end. 4 T30's in a back yard party can and will sound amazing... they just won't get you down there all the way to 30Hz really well.

Now, if we adjust the bottom frequency expectation to 35 or 40Hz and run the numbers on a 36" wide T48... where 35-40Hz will only need to be 12-15dB hotter than the mains to have a nice balanced sound with a full bottom end.



Adding the 26.5dB increase in output based on the 60 volt limit for the cab brings the maximum output at 40Hz measured at 1 Meter from 102dB to 128.5.

Adjust for our listening position, -6dB for every doubling of distance, brings us to 110.5dB.

Need 112dB and we're at 110.5dB, short only 1.5dB of where we want to be. So let's double the cab count until we get there, +6dB for every doubling of cab count. Well, 2 cab's put's us at 116.5 meaning we've met our goal and are now able to run this volume with 4.5dB of headroom, plunking away on only 315 watts.

Four, full 36" width T48's can be high passed at 35Hz, which means they'll play 30 and below, just slightly attenuated... And it would take a butt load of T30/T45's to even start to keep up, indoors or out. I highly doubt four full width T48's will leave you in need or want of anything different. I think the PRV driver is the latest hot ticket for those and they're affordable.

[T_Gowan]

Seth, this amazes me how you do this. Ive tried to explain this to sooo many people why one little sub stuck under 2 12 inch ported tops is not worth the effort. I have copied, I hope you don't mind, your above calculations and am forwarding it to a bunch of people. Thanks for this.

[Seth]

Seth, this amazes me how you do this. Ive tried to explain this to sooo many people why one little sub stuck under 2 12 inch ported tops is not worth the effort. I have copied, I hope you don't mind, your above calculations and am forwarding it to a bunch of people. Thanks for this.

By all means, Tom. Share away.

Although, I wouldn't personally say one little sub isn't worth it as a universal statement. It really depends on the intent of the user and the capability of the tops in question. Sometimes, if it adds ANY noticeable improvement, it's worth it. Even if it doesn't add enough to be properly impactful. But, if someone is designing a system to sound absolutely breathtaking... yeah, one isn't going to cut it outdoors, many times indoors too.

[Seth]

Some T48 review quotes over the years...

Myself and armchair pirate worked a renegade festival this weekend and we brought two of our t48s out, and I'll say, that was nothing short of a treat. I cant imagine why a majority of society would ever have a need for more than 2. These things make f1s f221 sound like small dice.We had people dancing 2 miles up the river follow the sound, and eventually find us to join the party. I never felt like i was anywhere near topping out at any point. But the ground in front of the horns was basically hovering at the kick. I dont know what you did bill but you did the shit out of it and I'm happy to rep your brand here in seattle. I wish leland still had those BFM name badges I would buy 8. Basically every attendee and musician was consistently absolutely floored by the sound being produced by your designs. I'm convinced anyone who doesnt enjoy the sound of these is either a paid shill or completely deaf.

...I think it's worth noting that the extension provided by 4 t48s is more than enough to deal with the vast majority of bass music. Even that wonky leftfield stuff. If you really need more than 35hz there are ways you can go lower but it involves setting lower voltage limits and sacrificing total output. Best to just leave it at 35hz. I work with bass music pretty frequently, almost as much as house music, and I've never once thought they were missing anything. The flexibility offered by the t48 makes them ideal in my eyes. If you are doing heavy bass I would recommend atleast 4 subs. But for content like drum n bass, breaks, trap, and whatnot 2 titans run down to 40hz is deeply satisfying.
As you could imagine the forest party in the photo was bonkers. These horns start doing some funky shit with 4 or more. I think that weekend was the moment I realized those horns are absolutely fit for bass music in a pile.

[kenzo]

Thank you for the excellent breakdown, Seth. It took me a few reads haha but I think I was able to track your explanation, why it is the case. I ran some of my FLACs through Audacity to actually verify if I needed the extension to begin with, and while the majority of them had greater than normal amounts of sub-30 content, the peaks even on the bassiest were 40 Hz and up. If the tuba has to sacrifice so much efficiency to hit those really low frequencies then it probably isn't a smart tradeoff. The last factor for me, then, would be how much can room gain and the like compensate for the tubas? I.e. is it worth building tubas for home and titans for outdoors? I'm very eager to try hit 30 Hz at least for home listening, but if it really is a bit of a fool's errand unless I go all out - I'll probably just go with the titans.

[Seth]

You're welcome. It is challenging to get the point across cleanly without being too dry for the reader to absorb.

What kinda room are we talking about? What are the rough dimensions and ceiling height? Carpet and furnishings? Livingroom, basement, garage, pole barn?

[Bill Fitzmaurice]

is it worth building tubas for home and titans for outdoors? I'm very eager to try hit 30 Hz at least for home listening

Not really, since in the home you have cabin gain that would boost the lows on the Titans anyway.

[Tom Smit]

I was tempted to suggest the T48, and you nailed it Seth. kenzo, in a room the T48 will get you to 30hz. Room gain will help you to get the volume increase that you are looking for, albeit, you might have to lower the voltage limit.

[himhimself]

I was in the Titan 39 or Tuba30/45 quandary for a good long while before I made my decision, and ultimately went with the Tubas for that small extra low end. Honestly, probably would have been happy either way, but I do love my tubas. And I went with the T30 over the T45 specifically so I V-plate and get some bonus db's for free. I used my pile of 4 outside recently and got the police called on me by multiple "neighbors", 1/4 to 1/2 mile away. And inside - OMG, they sound amazing. The Titan 48s just seemed to big for my purposes, and ability to transport in my little trailer was going to be a problem. Seth did provide a good case for them, though. In the end, just pick and go - pretty certain you will not be disappointed no matter your choice.