Best enclosure/driver for a metal-core bass drop

[Sydney]

Re: Best enclosure/driver for a metal-core bass drop

DIY Pro speakers in general don't have high resale value.
Of course expensive is relative ( like I mentioned earlier ).
I don't look at it as "wasted potential" but rather a compromise ( based upon Hoffman's Iron Law ).
The difference in output is negated if you have to use amp power to compensate for low output on the bottom octave.
And remember that the recommendation for BF horns: a HP filter need to be in place to attenuate the very frequencies that you stated as desirable ( the 30Hz range ) to protect the driver.
Also the length of a horn determines how low it can reproduce that is why they are need to be so big.

Maybe I misunderstand your intended use...
But if the application is NOT for FOH but rather to use on the stage - you are setting up for problems in that the stage will be subject to excessive low frequency high SPL sound which creates problems for ALL the stage members - that is why bands are behind the FOH system.
Historically bands have had to come up with ways to have high SPL out front without overwhelming the stage.

[RogueCow]

Re: Best enclosure/driver for a metal-core bass drop

the subs will not be located on stage, rather about 15-20 feet to the side. Loaded in a corner,

I had also been wondering about the high pass frequency...

Either way, are there any 18" bass reflex designs you know of, or would recomend? Or is this just a simple case of figuring out the desired volume and size the tuning port?

[Randy L]

Re: Best enclosure/driver for a metal-core bass drop

If you look at most pro-level 18" reflex designs, most will be rated down to low 30's.

For bang for the buck, though definately not in contention for the best pro-duty speaker, Carvin just came out with a 21" subwoofer rated down to 20hz (-10db) and 30hz (-3db). I see it's on sale for $479 each, and I doubt you'll be able to build one good 18" cabinet for that price. Just one of these just might be the ticket for your intended purpose.

http://www.carvinguitars.com/products/TRX1121

[Sydney]

Re: Best enclosure/driver for a metal-core bass drop

the subs will not be located on stage, rather about 15-20 feet to the side. Loaded in a corner,

I had also been wondering about the high pass frequency...

Either way, are there any 18" bass reflex designs you know of, or would recomend? Or is this just a simple case of figuring out the desired volume and size the tuning port?

For some reason I thought the band would be in the sound path....
Don't quote me but I believe it's around 45Hz ( If you want lower - the T60 is probably more apt )

PE has a woofer selection guide with suggested cab volumes for each driver it sells.
Manufacturers often list a few suggested sizes and give projections of performance.
I'm sure others have cost effective suggestions.

[RogueCow]

Re: Best enclosure/driver for a metal-core bass drop

considering some threads i have been reading where most of the "recognizable" bass lives around the 50 hz mark, i could probably live with something that cuts off around 40-45Hz.

Considering i could build 3 tuba30's for $479 (ish) i would build those before buying something pre-made.

Either way, to start i am only making one and want to stay $150-$200ish. And for that i was originally pointed towards a titan 48.

I still think that will perform the best for my needs, if not, i am sure i could sell it for cost after a couple of gigs.

[Sydney]

Re: Best enclosure/driver for a metal-core bass drop

Budget is almost always the constraint.
It was originally mentioned ( 1st post ) that a TF1525 was being considered - a quick review of the T/S specs shows that it's not going to work.
Now I think you can appreciate how Hoffman's Law relates to budget. ;)

[RogueCow]

Re: Best enclosure/driver for a metal-core bass drop

Budget is almost always the constraint.
It was originally mentioned ( 1st post ) that a TF1525 was being considered

That was back when i thought scoops were cool, new, and exciting lol

[Sydney]

Re: Best enclosure/driver for a metal-core bass drop

That was back when i thought scoops were cool, new, and exciting lol

I've met musicians that look at those in a similar way. I attribute that to nostalgia for their younger salad days.
Perception of sound involves psycho-acoustics. Human tend to perceive that which is louder as better.
The more astute salesman of audio equipment know this as well. And there are devices that create the perception of deep bass by manipulating and boosting the upper harmonics.
Most musicians ( I've met ) are not aware ( or care ) about this sort of stuff, so a cab that produces a high SPL creates an impression, even if only confined to a small portion of the bass spectrum, with uneven non-linear response elsewhere in the passband.

Actually when I mentioned Hoffman's Iron Law it is how the Dream is a speaker cab that play Low and Loud and it's Small.
And in addition - it's got to be Cheap!
But long ago it was accepted in Physics ( and Economics ) that there is no such thing as a free lunch.
Bass wavelengths ( below 100Hz) are over 11' in length, @ 50Hz over 22' in length.
To reproduce bass requires a large movement of air; Ever drop in octave requires that 4 times more air be moved than the octave above.
A big reason why the octave from 20 - 40Hz is "discarded" in live performance is that hard reality.
When musicians see how big cabs have to be ( to go Low and Loud ); they often reign in their goals and compromise to something smaller and more practical - especially if they have to move them around.

[billfitzmaurice]

Re: Best enclosure/driver for a metal-core bass drop

That was back when i thought scoops were cool, new, and exciting lol

Scoops (rear loaded folded horns) for the most part aren't what people assume them to be. For one thing they're not subs, they're bass bins intended to cross over to tops in the 500 to 800Hz range. They don't have higher sensitivity in the lows than reflex cabs. They were intended to be used with high sensitivity low Qes drivers. Said drivers trade bass response for high broadband sensitivity; the purpose of the horn loaded rear wave is to get some of that low end sensitivity back. They also suffer from a serious response dip where the front and rear waves meet at 180 degrees out of phase. These shortcomings explain why they've disappeared from the scene except in the hi-fi realm, where models using Fostex/Lowther full range low Qes drivers are aimed at the crowd who are willing to accept their shortcomings in return for their sensitivity and lack of a crossover.

[mdocod]

Re: Best enclosure/driver for a metal-core bass drop

Considering the budget sensitive nature here...

Have a look over at mcmelectronics if you have a chance. They have fairly ordinary looking vented bass bins in 15" and 18" size, but for so cheap it's silly. Granted, the drivers are nothing special (probably the inexpensive house brand they sell), but it's hard to argue with a completed, functioning bass bin for less than the cost of most 18" drivers.

They also have a 21" pro-sound woofer for ~$140 that might be worth a look. It would need a big vented box to come alive, but may represent a good way to get a nice chunk of displacement, and driver based gain from a simple box, rather than complex box based gain from a driver with less displacement capability.

Another angle to consider, is using really narly long throw "heavy duty hifi/car" type subs, planted in sophisticated horns to get the sensitivity and output. The Dayton titanic 10" and 12" can both be brought up to 95-105dB sensitivity with large horn loaded options, and can both dish out 120-130dB @1M from ~35-100hz in a large enough horn. I bring this up because, these drivers offer characteristics that are favourable for taking advantage of large box gain within "build-able and semi portable sizes." while at the same time, coming in at price points that are lower than many pro-sound drivers that tend to be called for in horn applications.

Regards,
Eric

[billfitzmaurice]

Re: Best enclosure/driver for a metal-core bass drop

Another angle to consider, is using really narly long throw "heavy duty hifi/car" type subs, planted in sophisticated horns to get the sensitivity and output. The Dayton titanic 10" and 12" can both be brought up to 95-105dB sensitivity with large horn loaded options, and can both dish out 120-130dB @1M from ~35-100hz in a large enough horn. I bring this up because, these drivers offer characteristics that are favourable for taking advantage of large box gain within "build-able and semi portable sizes." while at the same time, coming in at price points that are lower than many pro-sound drivers that tend to be called for in horn applications.

Regards,
Eric

Said drivers can work well in applications where response to 25Hz and lower is the goal. They don't work so well where the primary goal is high sensitivity above 35Hz, their Fs being too low and Qes being too high. Horn loaded or otherwise HT drivers tend to work best in HT applications, pro-sound drivers tend to work best in pro-sound applications.

[Randy L]

Re: Best enclosure/driver for a metal-core bass drop

Said drivers can work well in applications where response to 25Hz and lower is the goal. They don't work so well where the primary goal is high sensitivity above 35Hz, their Fs being too low and Qes being too high. Horn loaded or otherwise HT drivers tend to work best in HT applications, pro-sound drivers tend to work best in pro-sound applications.

+1 with Bill. Considering the small amount of power that will be driving this planned sub cabinet, I doubt anyone beyond the stage will really hear the bass drop if home or car subs are used.

[mdocod]

Re: Best enclosure/driver for a metal-core bass drop

Hi Bill, Randy,

Sorry, you're both wrong. It's the box volume and sophistication that plays the largest role in output capabilities, not the driver. The titanic 10" and 12" are, like any pro sound driver options, actually more or less along for the ride and can be "built into" any role just like the pro-sound drivers can. It's obvious that both of you are shooting from the hip without having actually modelled some comparisons. If a completed "box w/driver" has a sensitivity in the 40-100hz range of 95-105dB, it doesn't matter if it's a HT driver, or Pro-sound driver inside of it, if the sensitivity and maximum output is the same, then the crowd will feel it just the same. There are obviously trade-offs involved going to a HT/Car driver, but in this particular cases, it's a surprisingly good fit for the limitations involved.

The pro-sound driver is just one way to skin this cat. If you start with a lot of driver based gain, (low moving mass, high sensitivity, high Vas, high Fs, low Qts), then the amount of box gain possible within a given volume will be less. The box sophistication is forced downward. Most 18" pro-sound subs simply can not be practically built into portable horns (this is why we see mostly 15" drivers used in pro-sound horns), and so, tend to be used in direct radiator w/reflex tuning (no box gain over driver efficiency likely here). HT/CAR subs with low driver based gain, (high moving mass, low Vas, low Fs, higher Qts), can be "built up to" the sensitivity and output of the PA drivers through greater box sophistication within the same volume. The low Vas is really the primary factor that makes this "possible."

There isn't a "wrong" answer here, simply different ways to achieve the same ends. I am more than happy to show, that it doesn't matter if the OP picks an 8" long-throw driver with a sensitivity of [email protected], or a 21" pro-sound driver with a sensitivity of [email protected], if the box size remains the same, and the box gain through sophistication is allowed to vary with the different driver choices, the maximum output actually doesn't change all that much. The ideal thing here, is to pick a driver that matches the available budget, amplification and maximum box sizes allowed in a fashion that "makes the best use of each." In this case, considering that the OP has been tossing around the idea of other large horn builds. The available 450W of amplification is actually a very good match for a 10" titanic, which will be driven to the stops with that much amplification in the right horn, delivering [email protected]+ easily.


When a low sensitivity DRIVER is installed into a high gain horn design focused on 40-100hz, the system as a whole is no longer a typical "HT/CAR" sub. I did not make the suggestion to line the stage with inefficient sealed boxes. I suggested horn loaded, and listed the potential sensitivity and maximum output that I have seen in simulation from these drivers. Ignoring parts of my post, making assumptions, and effectively taking me out of context does not change reality.

Interestingly enough, I am not the first person to try to bring to light these realities on this forum. People have come here, and tried for years to get the great minds of this forum wrapped around the relationships of driver and box based gain for low frequency. Unfortunately, all who have come before have failed. I am simply the next in line, trying to bring truth where nobody will listen. Can the misconceptions ever be put to rest here? Perhaps not.

As an example, here's a $250 difinimax 4015LF @450W 9mm Xmax limited, vs a $155 TIT280C @450W 19mm Xmax limited, each in ~400L TH's adjusted to deliver the best possible output (that I could come up with anyway) from 40-100hz.

15" Difinimax


10" Titanic





Regards,
Eric

[billfitzmaurice]

Re: Best enclosure/driver for a metal-core bass drop

It's the box volume and sophistication that plays the largest role in output capabilities, not the driver.

True, but if the driver is incompatible with the design goal said goal won't be realized. Low Fs high Qes drivers are incompatible with high sensitivity pro-sound horns.

Can the misconceptions ever be put to rest here?

I have no misconceptions where horn design is concerned. My track record backs up that assertion.

[Sydney]

Re: Best enclosure/driver for a metal-core bass drop

argumentum ad verecundiam