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What people mean by "tune a box" or what freq the box "tuned

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What people mean by "tune a box" or what freq the box "tuned

Postby brakefluid » August 10th, 2015, 11:21 pm

As d topic says, I have only heard and read of this term on tuner. Of the few videos and web links that I have gone to, nothing was mentioned.

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Re: What people mean by "tune a box" or what freq the box "t

Postby nervewrecker » August 10th, 2015, 11:53 pm

I myself asked this question many years ago so I can try my best to relay the info.

You need to understand how a box works first. In a sealed box the air in it acts like a spring holding back the cone from moving. Bigger the box, less it holds back the cone like if you block one end of a syringe with your finger and try to pull back the plunger with a big and small syringe, same principle. This is why bigger a box more "sensitive" the driver becomes. I have done this in the past to make up for where I fell short on power. Takes more energy to produce a lower note that is as audible has the same effect as a higher note.
A sealed box can be tuned (although some may beg to differ).
Under the tuning frequency the air spring property can no longer hold back the cone and the cone acts like it in free air i.e. moves free and "bottoms out" / "unloads" with a characteristic "blop blop" sound. Over the tuning frequency the cone movement remains controlled.

A ported box uses not only the volume of air in the box but also a mass of air in the port that restricts movement. Below the point where this mass of air can no longer restrict the cone movement it bottoms out. Thats where your subsonic filter comes in.

With a sealed box the drop off freq is less steeper than that of a ported below the tuning freq. Cone movement is less erratic as opposed to the vented type.
All of this is not written in stone, it can be manipulated in many ways in the name of sound.

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Re: What people mean by "tune a box" or what freq the box "t

Postby black start » August 11th, 2015, 12:21 am

inside to learn...

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Re: What people mean by "tune a box" or what freq the box "t

Postby meccalli » August 11th, 2015, 8:44 am

https://en.wikipedia.org/wiki/Bass_reflex
Take a look at the sublink ' hemholtz resonance' as well. That is essentially the phenomenon that occurs with an enclosed volume of air and an aperture. Those two factors allow you to determine the 'tuning frequency' of the enclosure i.e the volume of air in the box and the physical characteristics of the port which alters the resonance produced by the port.

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Re: What people mean by "tune a box" or what freq the box "t

Postby brakefluid » August 11th, 2015, 9:08 am

But how is it actually tuned? Are solid objects placed inside to increase or decrease volume?
Or some special ribs are placed or something?
How is it actually done?

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Re: What people mean by "tune a box" or what freq the box "t

Postby nervewrecker » August 11th, 2015, 9:28 am

By tune, you mean the usable playing bandwidth above where the air masses have an effect on the cone.

For a sealed box, smaller the box, less air inside so harder to move the cone. Larger the box, more air, less of an effect the fluid inside has on restricting cone movement so it moves with more ease than in a smaller box. The exact freq where this restriction on cone movement no longer has a noticeable effect, the tuning freq is right above that.
For a vented its air in the box plus air in the port.

Bigger the box, closer you go towards infinite baffle.

Its like if you take out a vehicle shock. Try to move it in and out fast with your hand, the fluid in the shock restricts the movement. Now get a stronger pal, he can move the shock in and out a little faster and freer than you now. Get an extremely strong pal to try it, of course he can achieve much more movement.
Put it on a jackhammer and bolt down one end secure, might get free movement because the jackhammer can apply much more force to a point where the fluid no longer can restrict the movement of the shock head. You can get pardners stronger to try and move the shock head as much as they can and they wouldnt be able to unless they as strong as a jackhammer. The movements your pals can apply is the usuable playing bandwidth, the jackhammer is the bottoming out point where its below tuning freq and the shock head is the sub cone.

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Re: What people mean by "tune a box" or what freq the box "t

Postby meccalli » August 11th, 2015, 10:34 am

brakefluid wrote:But how is it actually tuned?

It's just a matter of equations.
Image
Fb = Enclosure Tuning Frequency
A = Air Compliance
V = Enclosure Volume
Fs = Speaker Resonant Frequency

Image
The classic equation terms.

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Re: What people mean by "tune a box" or what freq the box "t

Postby brakefluid » August 11th, 2015, 10:53 am

Ok i get that u have some technical calculations.

1. So if i have a sub and all the specs says is there is a 1 cube ported enclosure requirement. All i have to do is get that volume and port for it to be a spec built box.


2. Now if i am not contented with the spec "tune" i can increase or reduce the volume and porting to have a different tuned box? Of course calculations permitting to be all well and good?

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Re: What people mean by "tune a box" or what freq the box "t

Postby Soundstream_626 » August 11th, 2015, 12:08 pm

This term "built to spec" is an abused term. Most mean factory specs but sometimes you can get a result more tailored to your taste by adjusting the spec of the enclosure, but you would have to sacrifice a bit in one or more aspects. This can be power handling, frequency bandwidth etc.

So, for example I can build a box to play "louder" but I will be sacrificing lows and power handling etc. There is a reason these so called competition vehicles always have repaired or rebuilt subs. Too many people trying to defy physics.

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Re: What people mean by "tune a box" or what freq the box "t

Postby meccalli » August 11th, 2015, 2:01 pm

Soundstream_626 wrote:Too many people trying to defy physics.

:lol: this.

'Specs', the term is really the manufacturers specification on enclosures that they recommend as a guide to people who are just looking for a basic performance from their product, not necessarily the optimum performance . They provide specs with no idea of the build, application, environment etc. the woofer is going to be used in.

If you have an enclosure that's already built and you're not satisfied with the sound and wish to change the tuning, it's usually impossible to salvage and you need to rebuild with the exception of trying to influence the system in a minor aspect such as stuffing and port lengthening/shortening which is rather a finicky thing given how those aspects of port dimensions and enclosure volume mesh with each other.

The best thing is usually to start with your goals on what you'd like to get out of the system, and then select a woofer based on the working space/ application/ musical/ loudness goals and then have an enclosure built with these things in mind after modeling/ sims in software.

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Re: What people mean by "tune a box" or what freq the box "t

Postby nervewrecker » August 11th, 2015, 5:07 pm

Yes you can increase or decrease internal volume, port length, port area etc to suit you.

As said before its a give and take so know what you doing or start searching for a good repairman one time.
Can model a response curve in one of those programs it have out here for a reasonable estimate as to how it will play off.

X50 on men trying to defy laws of physics.

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Re: What people mean by "tune a box" or what freq the box "t

Postby Ted_v2 » August 12th, 2015, 7:13 am

black start wrote:inside to learn...

x2

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Re: What people mean by "tune a box" or what freq the box "t

Postby aliman » August 12th, 2015, 8:05 am

very interesting topic, i build a lot of boxes for car systems, when it came to TUNING the sub box, i would decide how many watts and what frequency i wanted, set the eq\crossover and amp then listen to my build to spec seal or ported sub. every time and more than once report , invert speaker or redesign the box but around recommend specs until i got the frequency i wanted, that same box would not work in a different car. this method worked for me

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Re: What people mean by "tune a box" or what freq the box "t

Postby brakefluid » August 12th, 2015, 2:33 pm

Nice down to earth response aliman. U interested in "tuning" a box for a triton?

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Re: What people mean by "tune a box" or what freq the box "t

Postby nervewrecker » August 12th, 2015, 5:49 pm

aliman wrote:very interesting topic, i build a lot of boxes for car systems, when it came to TUNING the sub box, i would decide how many watts and what frequency i wanted, set the eq\crossover and amp then listen to my build to spec seal or ported sub. every time and more than once report , invert speaker or redesign the box but around recommend specs until i got the frequency i wanted, that same box would not work in a different car. this method worked for me

Wah? 0.o



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Re: What people mean by "tune a box" or what freq the box "t

Postby ruffneck_12 » August 12th, 2015, 7:42 pm

aliman wrote:very interesting topic, i build a lot of boxes for car systems, when it came to TUNING the sub box, i would decide how many watts and what frequency i wanted, set the eq\crossover and amp then listen to my build to spec seal or ported sub. every time and more than once report , invert speaker or redesign the box but around recommend specs until i got the frequency i wanted, that same box would not work in a different car. this method worked for me




How long ago was this?

It have programs to simulate these things now :lol:

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Re: What people mean by "tune a box" or what freq the box "t

Postby aliman » August 12th, 2015, 9:41 pm

ruffneck_12 wrote:
aliman wrote:very interesting topic, i build a lot of boxes for car systems, when it came to TUNING the sub box, i would decide how many watts and what frequency i wanted, set the eq\crossover and amp then listen to my build to spec seal or ported sub. every time and more than once report , invert speaker or redesign the box but around recommend specs until i got the frequency i wanted, that same box would not work in a different car. this method worked for me




How long ago was this?

It have programs to simulate these things now :lol:

nice!!! remind me that i am old :)

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Re: What people mean by "tune a box" or what freq the box "t

Postby aliman » August 12th, 2015, 9:46 pm

brakefluid wrote:Nice down to earth response aliman. U interested in "tuning" a box for a triton?

thanks for the offer but new hobby is ATV's got work up to my neck, still enjoy hearing a nice clear system

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Re: What people mean by "tune a box" or what freq the box "t

Postby ruffneck_12 » August 13th, 2015, 12:14 pm

aliman wrote:
ruffneck_12 wrote:
aliman wrote:very interesting topic, i build a lot of boxes for car systems, when it came to TUNING the sub box, i would decide how many watts and what frequency i wanted, set the eq\crossover and amp then listen to my build to spec seal or ported sub. every time and more than once report , invert speaker or redesign the box but around recommend specs until i got the frequency i wanted, that same box would not work in a different car. this method worked for me




How long ago was this?

It have programs to simulate these things now :lol:

nice!!! remind me that i am old :)



Lol sorry

Seems like hell tho.

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Re: What people mean by "tune a box" or what freq the box "t

Postby brakefluid » March 23rd, 2016, 4:06 pm

Ok so after much reading and searching, tuning a box has more to do with porting. That is the length of the port and cross sectional size.

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Re: What people mean by "tune a box" or what freq the box "t

Postby Soundstream_626 » March 23rd, 2016, 5:09 pm

brakefluid wrote:Ok so after much reading and searching, tuning a box has more to do with porting. That is the length of the port and cross sectional size.


in relation to a specific net volume. Vb

Image

Fb = tunign freq in hz
Vb = net airspace in cubic inches
Av = vent area in sq inches
Lv = effective vent length in inches

different subs will respond differently per a given box, so its not really a universal thing.

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Re: What people mean by "tune a box" or what freq the box "t

Postby ruffneck_12 » March 24th, 2016, 7:25 am

Soundstream_626 wrote:different subs will respond differently per a given box, so its not really a universal thing.


This should be on a banner at the top of the ICE forum page

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Re: What people mean by "tune a box" or what freq the box "tuned

Postby brakefluid » March 12th, 2018, 11:38 pm

So in keeping with the 1st post of this thread and NOT getting technical, tuning an enclosure in its simplest terms is port sizing- that is port cross sectional area and port length. They however work in relation to a number of factors.

My own sequence is as follows:
1. Choose your sub- different subs have different frequency sweet spots. Lets say 35hz

2. After choosing your sub you need to know the minimal cross sectional area of port size required. For this you plug in your driver size, number of drivers, xmax and your desired frequency. Try to find the xmax figure for the sub that you are using otherwise online calculators use std info.

3. So now you will know your min port area to avoid port noise. So if the min req is 3sq inches or 2.25" diameter, now you design for your port to be bigger than the 3 sq inches or the 2.25 diameter. If using pvc the next best size in this example is 3" diameter.

4. Now you need to calculate your vent length. Again use an online calculator. Plug in your port type (square or round), qty of desired ports, desired area/diameter of ports, and enclosure volume ( based on sub size and qty), and lastly what frequency you wish to have the enclosure tuned to.

Your calculations would give you the required port length.

My info is based mainly on one of my readings here:
http://www.carstereo.com/help/Articles.cfm?id=

Lastly, your total enclosure internal volume will now be:
1. Sub manufacturer's recommended ported enclosure volume plus
2. Volume of the actual sub displacement plus
3. Volume of the ports.


Of course for all the above, it should be endorsed by the wiser forum gurus.

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Re: What people mean by "tune a box" or what freq the box "tuned

Postby Rovin's Audio » March 13th, 2018, 12:31 pm

though im out here long i still not a expert cause u can never stop learning & experiencing but i will scratch d surface with a few of my personal views


i advise using a box tuning program BEFORE u buy ANY sub - ALOT of ppl make this mistake

yes some subs perform better at certain zones then others , some can give u a flat response , some peaky at where u may not like it to peak

some subs may require huge cuft for a certain response , others a surprisingly small cuft so u just cannot watch any 12" & say well most will work in a 2-2.5cuft , u can be way off as much as a 1-1.5cuft

most recommended specs are peaky & or compromised so as to appear that "it wont take up much space"

slotports - some may require a port so long it will be challenging to fold a port for it which can easily take up 1cuft+ or just as much as d sub requires

for 99% of vehicle owners space is a concern - u may want a 15 or want to still have space for a cooler or groceries but not have sufficient cuft so same model 12 in correct enclosure will outperform a 15 in a undersized box ,

tune ur sub\box to what U listen to & like , dont do like most trinis & do ur music to please other ppl , spend ur $ on urself not for others to hear ..... also i especially hate to hear ppl wanting a 8 to sound like a 12 just to impress others when they have space that can comfortably fit a 12


its not just only sub & enclosure design but ability of amp to reproduce all freqs equally which plays a huge role too ... this is a whole other topic

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Re: What people mean by "tune a box" or what freq the box "tuned

Postby ruffneck_12 » March 14th, 2018, 4:00 pm

Tuning a box is just like tuning a car
It's a science, not an art.

Sometimes it's better to pay somebody to do it for you because the learning curve is steep, and you need at least Cape level physics to really do it good.

(cxc physics good enough for wiring, but not acoustics)

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