Subwoofer construction help plzz :(

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hi
i wanna build a sub for my bass guitar ..
i donno too much bout the construction of sub-woofers case... :( ..
i just design this like FBT sub - woofers for my 12 " sony xs-l121p5 car subwoofer... can any body plzz look at my desgin & tell me how is it ? ..
is dimensions good ? ... any idea ? .. how is the iner construction ?
i ll be grateful for any idea ...
and another question ...
i wanna put my amp into this ..
i donno which arrangment is good ? .. i mean :
input ===> subwoofers filters & eq ===> subsonic filter ===> preamp ===> power amp ===> delay & short circuit protction ===> out ...
or :
input ===> preamp ===> subwoofers filters & eq ===> subsonic filter ===> power amp ===> delay & short circuit protction ===> out ...

is it good ? .. any idea plzzzzz ?
any good idea ? any good schematic or pcb layout for subwoofer filter & eq , or preamp ? ( i wanna use ESP p68 as my power amp )
 

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Speaker Choice

Hi Ahmad_tbp;

I could be wrong here so new information would be appreciated from anyone...

but...

A subwoofer speaker designed for car or home use would be very unsuitable for a bass guitar speaker. The efficiency and ruggedness of these would simply not cut it, particularly for stage work.

You need to look for extended low frequency PA (public address / musical instrument) drivers for your application. These will give you the efficiency and toughness required. Manufacturers such as JBL, RCF, Peavey etc come to mind, but be warned these units won't be cheap. See if you can find a well cared for second hand bass-box in the musicians trading columns.

Cheers :drink:
 
it seems i should forget bout it :( ...
as i said befor in my posts .. a bass amp is too expensive in here .. tooooo expensive :( ... after years i could nt buy a second hand amp yet ! ,, i couldn t find !!!
so what do u think ? .. i have to build this amp ?? .. which subwoofer u offer ? .. somethin that i can find in here ? ... there s lot s of car subwoofers here ,, clarion , jbl , anythin :( .. they r not suitable ? ...
and are the power amp & other sections good ?
is the case good & suitable ?
& thnx DonoMan but i cant buy anythin from net :( ...
plz help me .. :(
 
Hey Ahmad_tbp,

Yes JBL make car subs too but these are nothing like what is required in a bass guitar rig.

Unfortunately good bass boxes for bass guitar are physically large and usually have one (or two) 15" or even 18" PA / musical instrument speakers.

I remember seeing some RCF's that would do the job and they seem to be good value for money.

The power amp would be a good project to do and if you use second hand parts (as I did with my amp project) you could build it for very little.

Then you could buy or build the pre-amp section (could be quite complex) and work on effects units later.

Good Luck
 
Sub-Woofer

A quad box or maybe 2 x 15" subs could work because you would gain some efficiency by using extra speakers.

Most sub woofers that I have seen have efficiencies of 88dB or so (1w @1 mtr) compared tp PA drivers of around 94dB+.

So if you buy the most powerful sub woofers you can afford and then deliver only about half their rated power you should be ok.

You could build a quad box with 4 x "100w" 12 inch sub-woofers (check the real power rating) and end up with a 200 watt RMS 4 ohm box with an efficiency of around 92dB+

This would even cost less than one JBL.

The reason the numbers for the power rationgs don't add up is because I don't trust what's written on the box and I divide the power specification by 2. Also consider that a bass guitar note that isn't damped is basically a sine wave and this is very tough on speakers.

But if this is a practice amp with some light stage work then go for it!

Cheers: :drink:
 
Your design is a dual bandpass subwoofer, a bit complicated for a first try, if it's designed by Sony to go with this subwoofer it's ok, but if you want to change the dimensions or something, it will probably sound very bad.

I suggest you to go less complicated for the first time, especially if you don't know the T/S parameters on the woofers you are going to use.

Go for a big sealed box, bigger = louder, and use several drivers if you can, like if you find a good deal on two or four 12" drivers of the same brand, same model, go for it.

You can make something not that bad, don't worry.

If the bass notes are not loud enough, you could tune the box with a long ABS pipe, but doing this is harder if you don't know the parameters at first, we would need to know the internal size of the box too.

For the component chain, I would go with this:

imput --> subsonic filter --> crossovers and eq ---> preamp --> power amp --> delay and short circuit protection ---> output
 
What Box?

A correctly built horn loaded box could be too big physically as a Bass rig you want to cart around.

The quad box or dual 15" rig in a sealed or ported box would be the way to go. It would be easy to port whatever box Ahmad_tbp ended up with for a good and deep sound. Remember we are not talking about hi-fi here so issues with port chuffing will not be a problem (no-one will hear it on stage).

I built 2 quad boxes a few years ago with the primary design consideration being able to fit through the back door of my car. I then ported the box using bass box parameters. How does it sound? wicked !

Everyone here is genuinly tring to help you Ahmad_tbp. Ultimately though try not to get carried away and the Sony design is getting carried away.

Go have a good look at what other base players are using and then build a similar box. Stuff it with your sub-woofers wire them up and then tune the box to get the correct bass extension. I and others here will show you how to do that (it is very easy).

Good luck :drink:
 
hi quasi,simon5,DonoMan.. thank u so much for help me ,, thank u so much ,,,
so u think it s better if i tryin to build a seald 4*12" or 2*15" box .. huh ? ...
i just looked at ampeg s a 4*12" & 2*15" cabinets ...
http://www.ampeg.com/products.htm?product=94&catid=11
http://www.ampeg.com/products.htm?product=31&catid=11
... what bout their dimensions ? .. are they good for me ? ..
i really donno what to do :( .. unfortanately i donno if i can buy 4* 12" good sub .. lol it s so funny !!! i donn have enough money to buy a bass amp , i don have money to build one ! & i want to have one ! .. lol
& what do u think if i just buy another sony p5 sub and build a duel 12" cabinet ? :p ...
& one thing else . that design is mine i really donno anythin bout what is T/S parameters ... i never see an inner subwoofer construction ... i just saw a fbt 12"dimensions .. & design a box like that , & think what is the inner construction can be ... & i think they may build it as i designed .,, so i draw it ! :p ... and now i found out i designed a dual bandpass subwoofer !!! lol
thnak u so much so much for help ,, i m so gratefull ..
i ll tryin to buy another sony sub :p . i really cant build a quad cabinet :p .. it s tooo expensive for me :( ........
:dunno:
 
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