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JakeGrover
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Joined: Mon May 28, 2018 6:09 pm
Location: Upstate New York

Hello

#1 Post by JakeGrover » Tue May 29, 2018 1:56 pm

Hi!
My name's Jake. I'm in upstate New York. I'm building a recording studio in my basement. I make electronic music and do voiceovers. I occasionally DJ and even more rarely do live sound for events.

A couple of friends of mine built 2xSLA Pro and 2xTitan 48 and they have been singing their praises.

I'm considering building 2xTuba 39 for my first build.

I'm also considering making 2 sealed 18" subs for a number of reasons.

I would eventually like to have 4 subs that can be run in mono in my studio to even out low frequency response.
I currently drive a Honda Accord and have to borrow my wife's Subaru Forester for gigs (32”x37”x62” cargo capacity with seats down).

My next gig is June 30th, I'm borrowing some tops, but I would like to have at least one sub bought or built by then so I do not have to borrow one of those as well.

Thanks for all the great info!
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Grant Bunter
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Re: Hello

#2 Post by Grant Bunter » Tue May 29, 2018 3:51 pm

Hi and welcome Jake :)
Sub choice comes down to content reproduction required. If you're happy with 45Hz minimum with that, T39's will do that as a pair.
BTW, the T39's are Titans, not Tuba's,

You shouldn't use 2 different designs in the same passband. The 2 different types will have phase anomolies leading to frequency cancellation.
So it is one design, or the other, not both.
The T39's will beat 18" loaded cabs, check out the SPL chart section...
Built:
DR 250: x 2 (melded array) with March 2012 plans.
T39's: 4 x 20" BP102 , 2 x 28" 3012lf.
WH8: x 3 with melded array.
Bunter's Audio and Lighting "like"s would be most appreciated...

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JakeGrover
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Location: Upstate New York

Re: Hello

#3 Post by JakeGrover » Tue May 29, 2018 4:55 pm

Hey Grant!

Thanks for the welcome!

Right, Titan 39s. Typo.

Right now I’m leaning towards the Simplexx 18. I’m wondering if there is a way to open and close the ports.

When mixing music (80-90dB) I’d like to be able to hear those 20-40Hz tones and I’d like them to be accurate. When used as a PA, I’m not expecting to get 100dB at those frequencies so opening the ports for more 35-40 would be nice. I imagine that:

A) it won’t work because it would be hard to build the port covers air right (magnets, cam locks, and trunk rubber/weather stripping?)

B) it won’t work because there are other design changes to the sealed vs ported enclosure

or
C) it would work great! No trade offs! Wishful thinking?
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Bill Fitzmaurice
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Re: Hello

#4 Post by Bill Fitzmaurice » Tue May 29, 2018 5:05 pm

JakeGrover wrote:
Tue May 29, 2018 4:55 pm
When mixing music (80-90dB) I’d like to be able to hear those 20-40Hz tones and I’d like them to be accurate.
You won't, unless you've got a couple of Tuba HTs and do your mixing in a living room sized space. You're fighting the laws of physics, and the law always wins, not the least of which to consider here is Equal Loudness curves.
Also, sealed subs don't go as low as ported.

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JakeGrover
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Re: Hello

#5 Post by JakeGrover » Tue May 29, 2018 6:30 pm

Thanks for replying, Bill.

The room is 11’x25’x7’5”. I do not know if it’s acoustical dimensions will correspond to its physical dimensions, because I haven’t finished sealing my doors and windows so I don’t know how leaky the room will be (hopefully not very). If the seals aren’t tight, it may behave like a larger room at lower frequencies (and wake up half the neighborhood)

The room will be treated to the point where it is as flat as possible across the spectrum. My acoustic testing has stalled, because I don’t have subs powerful enough to excite the room modes at lower modal frequencies. Currently I only have a Yamaha HS10W to test and it distorts before it can excite the room (which makes it look super flat... but not what I’m going for).

My understanding is/was that ported subs achieve higher SPL until they reach their tuned frequency and then roll off in a less predictable manner than sealed subs do. Sealed subs cannot achieve the same SPL as ported subs, but they generally have a more linear response. According to google they also have “less phase rotation, lower group delay, and reduced ringing in the time domain”. I know what one of those things means.

Mixing is generally done around 75-85dB. According to your SPL charts 1 Simplexx 18 can hit 85dB at 25 Hz and 80dB at 20Hz. I assumed that 4 Simplexx 18s strategically positioned around the room (1/4 of room dimension from boundaries to even out modal interference) would be able to do increase SPL by about 6dB at 20Hz to get it close to 85.

If I could use the same system to hit 95dB at 40Hz and fit 2 of them in a Subaru... that would be a good thing.

I realize that I’m trying to meet multiple criteria on a budget and that doesn’t often work, but I figured it would be worth a shot.

Please disillusion me of any bad information I’ve repeated here. I’m no expert, just a guy on the internet.
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Bill Fitzmaurice
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Re: Hello

#6 Post by Bill Fitzmaurice » Tue May 29, 2018 9:10 pm

JakeGrover wrote:
Tue May 29, 2018 6:30 pm
My understanding is/was that ported subs achieve higher SPL until they reach their tuned frequency and then roll off in a less predictable manner than sealed subs do.
Their roll off is 100% predictable. The problem with sealed subs is F3 that will run around 30-35Hz, no matter what driver is used. Ported F3 of 20Hz or lower isn't difficult to reach, but the cabs have to be large.
Sealed subs cannot achieve the same SPL as ported subs, but they generally have a more linear response.
Not true.
According to google they also have “less phase rotation, lower group delay, and reduced ringing in the time domain”.
You can't hear phase, you can't hear group delay, and ringing in the time domain isn't a concern with well designed subs. As for mixing anything down to 20Hz, there's some benefit to that with the LFE channel of a Blu Ray disc for home theater, none with music. If you really must reach 20Hz with authority use the THT. But no sub that works well that low can also do double duty for pro-sound, they're just way too far apart in their design parameters.

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JakeGrover
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Location: Upstate New York

Re: Hello

#7 Post by JakeGrover » Thu May 31, 2018 8:43 am

Bill,

Thank you for correcting my errors. As you can tell, I do not know much about speakers or subwoofers.

Temporarily my sub build is going to be on hold, since I just got 2 Yamaha SW118iii subwoofers from Craigslist for $200. I know that I will outgrow them, but I couldn't pass them up at that price. I will almost certainly end up selling them, but they will be fine for the few gigs I have lined up this summer (indoor, small/medium sized rooms). 1 of them at less than half power in the corner of my studio was reading at 75dB at 32Hz (on my phone, I will use a reference mic next time). I am sure that corner loading and modal reinforcement is playing a part in this.

When I am ready to build, I'm wondering if the slim Tuba 60s would be a good option for me. 2 of them at 15x30x60 would fit into the car and leave room for tops and an amp rack.

For tops, I like the small profile of the SLA. I could start with 2 and add 2 more if needed.

I guess for now, I will get some amps together to power what I've got and build the speakers later.
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