Bass extension in tower speakers

T

TankTop5

Audioholic General
I spent some time thinking about building diy subwoofers and found out it’s pretty easy using box and port design to get down to 20hz and below. Is there a trade off doing this in a floor stander full range speaker? I understand a subwoofer is a much simpler speaker to design but is really that difficult to get a full range tower?
 
lovinthehd

lovinthehd

Audioholic Jedi
Easier to find proven designs for the subs than truly full range loudspeakers IMO....as to designing your own, go for it!
 
ryanosaur

ryanosaur

Audioholic Spartan
The Bass Cabinet is largely the same thing... the complication comes when you add Midrange Drivers. If you delve into most Cabinet design for 3-way Speakers, you will see that the Mids need their own chamber which may or may not be ported.
The kicker then becomes the size of the overall cabinet, and whether the Front L/R speaker locations will provide good acoustical homes for the Lower Frequencies that you are talking about. (Enter Geddes system for placing multiple subs in a room and that he considers full range mains to be low frequency sources... I digress.)

Look at some of Troels Gravesens designs to see how he incorporates Powered low end bass Drivers into a 3-, 4- and even 5- way design. These are not small seakers, but he does have cabinet illustrations and build photos so you can see the complexity of the design. ;)

So yes, it can be done, has been done, but needs special consideration like Active low-end/passive Mid/High end, or just straight up active design across the board.
 
Pogre

Pogre

Audioholic Overlord
Most subs tend to have their own power source, separate from the rest of the gear and usually more of it too.
 
S

Sadie42

Audioholic Intern
There is no free lunch ...

“If we study the efficiency equation we can see that in order to achieve one octave of bass extension requires a payment of a factor of 8 in efficiency or box size. For example, say you have a system that has a F(3) of 80 Hz and you want to redesign it so that it goes to 40Hz.You could either make the box 8 times larger or have the system end up 1/8th as efficient. Or you could make the box twice as large and end up with 1/4th the efficiency. Either way, you must PAY mother nature for the extra octave of bass. There can be no cheating.”

“It is also important to realize that for typical closed and vented box systems the efficiency of the system is totally determined by the choice of driver. Once a driver is selected you can vary the enclosure to change the bandwidth but the efficiency will not be affected by the choice of enclosure. So driver selection is VERY important in the overall design procedure. In other words, don't expect to get a lot of low bass from a super efficient pro sound driver. On the other hand, don't expect to build stage monitors using low efficiency hi-fi drivers.”

 
Verdinut

Verdinut

Audioholic Ninja
Here is an example of a Gravesen 4-way design using active low end and passive mid/high end:
For the construction of a good peforming DIY 4-way speaker system, you need to have the proper knowledge and you would be involved with a lot of trial and error work. In order to start building speaker cabinets, unless you buy a kit from a specialty raw speaker distributor such as Parts Express, Meniscus or Madisound, it is suggested that you begin with a 2-way system. When you have succeeded with the 2-way loudspeaker, then you can move on to attempt building a 3-way system.

Here is a book which I recommend the OP to get to learn more about the functioning of loudspeaker drivers and building enclosures:

 
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ryanosaur

ryanosaur

Audioholic Spartan
@Verdinut
Indeed... everything you said is spot on, and as I understand it, everytime you add an XO point in a passive design, you get many more challenges in making the different bands work smoothly together. I do not know how a hybrid Active/Passive interact.
Either way, cabinet complexity is also boosted significantly.

The Alden book is one of my favorites, a very worthy read. For those that need an easier introduction, the Weems and Murphy books are great getting a more basic understanding.
 
TLS Guy

TLS Guy

Audioholic Slumlord
I spent some time thinking about building diy subwoofers and found out it’s pretty easy using box and port design to get down to 20hz and below. Is there a trade off doing this in a floor stander full range speaker? I understand a subwoofer is a much simpler speaker to design but is really that difficult to get a full range tower?
If you are going to build a truly full range integrated speaker, then it really should be an active design. I use full range speakers in my theater, and they work very well. They are very large though. If you are going to also use them in the HT environment then you need to mix in the LFE channel. It does actually get quite complicated, but in my view well worth it. Time alignment matters. Separating fundamentals from their harmonics spatially, is not cool at all. Hearing my rig would convince you of that in a hurry.

Full range speaker.

 
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Kvn_Walker

Kvn_Walker

Audioholic General
I spent some time thinking about building diy subwoofers and found out it’s pretty easy using box and port design to get down to 20hz and below. Is there a trade off doing this in a floor stander full range speaker? I understand a subwoofer is a much simpler speaker to design but is really that difficult to get a full range tower?
Efficiency is an issue. Bass extension, high efficiency, enclosure size... "pick two" the saying goes.

You can get deep bass in a tower but you either need a huge box or a very low system efficiency.

There's a reason subs have much larger amps than what most tower speakers can handle. They need lots of power to reach the same volume.
 
Verdinut

Verdinut

Audioholic Ninja
@Verdinut
Indeed... everything you said is spot on, and as I understand it, everytime you add an XO point in a passive design, you get many more challenges in making the different bands work smoothly together. I do not know how a hybrid Active/Passive interact.
Either way, cabinet complexity is also boosted significantly.

The Alden book is one of my favorites, a very worthy read. For those that need an easier introduction, the Weems and Murphy books are great getting a more basic understanding.
As a matter of fact, there are not that many commercial 4-way loudspeakers that perform well, as most of them show phase, dispersion and lobing problems. Frankly, it is more practical to build a well balanced and smooth sounding 3-way system with drivers with sensitivities and frequency ranges that match well together.

With regard to what you call hybrid active/passive systems, there shouldn't be much challenge in implementing them. It's not that much more complicated than having to build and voice a passive crossover. As you know, connecting a powered sub to a receiver results in an active/passive system using active Xovers for the sub channel.

On my HT system, I am using the QSC XC-3 active crossovers to bi-amplify the front cabinets. One channel of a DCA 1222 is used for the sub and the other for the mid-bass drivers with the filter point at 200 Hz. The only adjustment I had to make was for the gain setting on each channel because of the sub's lower sensitivity .

 

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