What FB for fidelity audio in a bass refex box

[Ground Zero]

Hello

I need your advices please to build a bass reflex box for my subwoofer Ground Zero Gzuw12X to have a great quality of the sound with deep and clean bass when i open the trunk of the car please.

In the manual of the box from ground zero they says a Bassreflex box of 50 liters and a vent of 10cm of diameters and 30cm in length.

but i the manual of the sub ground zero say 32 liters for the box with a vent of 10cm of diameters and 26cm in length.

Can you tell me what is the good box please ? because ground zero don't answer me

because when i use the thiele small parameters i calculated a 35,59 liters with this formula:

VB= S x VAS x QTS²

S: is a coef of 5.7 a standard in high fidelity

Thanks for your help

[jol50]

I always build what I want but I like them deeper, so that is usually the largest factory box or larger. If you want to input maximum power you may have to use their box or it may not handle as much tuned lower.

Otherwise I try to tune it to the car, and me. I put a spare sub and box in the car and EQ it the way I like. Then I model it and add the EQ settings to it. Then I model prospective new sub so it looks like that. It gets me close and includes cabin gain for that car.

[Ground Zero]

Hi jol50

Thanks for your advices, but i don't want to tune with an EQ, i prefer to have FB it is more simple

thus i'll test a 35 liters box with a FB of 42 hertz

do you thinks it's a good FB ?

Thanks

[jol50]

It depends on how low you want it to go, what you like in the sound of a sub, how much cabin gain your car has. I tune around 25-35Hz for most of my sub boxes but I like them to be capable of playing 30Hz minimum in the car. Since they take more power and play louder SPL in a smaller and higher tuned box, those are typically recommended by manufacturer and tuned too high for me. That is not always true, but often. I like IB subs the best as they can hit 20Hz if you have enough cone area and the right subs.

I'd say build the box on the larger side if you can, because you can change the port tuning anytime to what you like and even tune the box higher. If you like tight bass then don't worry about it just go with the smaller recommended. I model all of mine, don't use recommended very often.

[Ground Zero]

Thanks

so i'll try just the box at 35 liters with a tuned box at 35 hertz because i love deep and clear bass at high volume the sound must have a great quality i dislike bass like boom boom with poor quality

in fact i would like to have a hi-fi car

[event horizon]

Car subwoofers are notorious for having Thiele/Small parameters that look great on paper but have no resemblance to reality

If i was you i'd measure the driver parameters yourself & then you can design something accurately. seeing as you want clean & deep bass that is the only way you'll ever make it accurate.

Here are a couple of examples from two totally different manufacturers.

Claimed Qts - 0.332, reality - 0.887
Claimed Qts - 0.35, reality - 1.068

As you can see, there is no way on this earth that you'll ever get an accurate bass response unless you measure the driver yourself. Unfortunately you may find that the driver could never be used in a ported box, it saves you making one with all the associated costs & time if you measure beforehand.

I'd be surprised if the driver specs were accurate, sorry, but there you go

[Ground Zero]

Hello event horizon

Thanks

Yes i do that i have tested the thiele small parameters with the WT3 from Dayton audio

Dayton Audio - WT3 Woofer Tester

do you think it's a good tester ?

for the parameters there are similar only qts are a little high but i think this come the cone of the subwoofer because the material use for the cone is aluminium and this material is cold.

because when i heat with the hairdryer the cone with a temperature of 25°C the parameter is the same on paper.....

for the others parameters all is ok

this is the thiele small parameters of my subwoofer groundzero gzuw12x

http://www.ground-zero-audio.com/13_...all_Woofer.pdf

but i don't know if parameters are with the voice coils in serie or in parallel ?

can you help me please ?

Thanks

[event horizon]

Hi Ground Zero, it won't make a difference to Qts or Fs or Vas (which are the most important factors) whether the voice coils are in series or parallel. As long as both are used you'll get the same Bl & thus the same parameters.

With a driver Qts of 0.42 you'll want a bigger cabinet than the drivers Vas if you want it to go deep & clean. The box tends to be nearly exactly the same as the Vas when the drivers Qts is about 0.375. You'd need a smaller box with a lower Qts & as i said a bigger one with a Qts above 0.375.

It won't need to be a lot bigger, i could model it in winISD if you like & find out the ideal box size & port tuning frequency. Or you can do it yourself if you have winISD

Let me know, we are all here to help (in general ).

E2A:- I can't comment on the tester as i do it manually with a precision resistor, function generator, frequency counter & multimeter. Sorry chap.

Bests, Mark.

[Ground Zero]

Thanks a lot event horizon

yes i have winisd but if you can calculate a box with a port please ?

because i compare it with my model in winisd

[Ground Zero]

and can you save the file form winisd and post it on the forum please ?

Thanks a lot