center channel

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hello,

i am very new to diy i have recently built 3 subs.

thing is that i have a harman/kardon avr 3550 receiver. 85wx5
i dont have a center channel.

i am thinging of building a chenter my self.

son can any one give me a idea of how i can build it.
i am willing to use fullrange drivers and a piezo tweeter.

wut tweeter should i use? like piezo or a papercone tweeter?
( keep in mind i live in india we dont get any drivers from fancy international brands so its all local stuff)

also r fullrange drivers good or should i use woofers?

if its a configuration of 2 drivers and 1 tweeter, can i connect all in series and the tweeter in paralel and connect it to the amp? or do i need to put some capacitors and resistors?

should i make a ported enclosure or a sealed one?

i think loudspeaker making is much easier than making a sub.
 
As ever, whether the box is sealed or ported will depend on the drivers you use.

It might be nice to try a fullrange design with a piezo tweeter just coming in for 8-12kHz and up. This means you don't have a crossover in the voice range so it should sound quite coherent and natural providing you source a nice fullrange driver. You may also be able to get away with a minimal crossover which will be easy to design.

The downside (if you can call it that) of this approach would be that the box would have to be an upright design as opposed to the more common, horizontal, lay-down type.
 
Your driver will need to be shielded if your TV is a CRT type, or the stray magnetic field will distort the picture. The piezo tweeters have no magnet, so they wont be a problem. Just put a 8-10 ohm 2W resistor across the piezo terminals, and use a series cap of about 2 or 3uF to tie them to the woofer terminals. It is quick and easy, and should work reasonably well.
 
The easiest thing to do is use a shielded fullrange driver like the CSS WR125S @

www.creativesound.ca

I have one of these in a ported box sitting on top of my TV right now, just waiting for laminate to arrive to finish the boxes. The sound is VERY good, and stays locked to the picture at all times. No crossover, just design an appropriate box, stick your driver in, and run a wire to your reciever. If you have no access to crossover design tools or measurement equipment, this is your best bet, or use a respected kit like the Adire LCC or Audax HT center channel.
 
hey hornlover,
i am planin to use two 3or4 inch woofers and a piezo.
so do u think i should use fullrange or woofers?

and abt that crossover u told me abt,

ur sayin that i put a resistor or 8-10 ohm in parallel to the tweeter and put a 2 capacitors that is one with each woofer,

-(speaker)-(capacitor)-(tweeter)-(capacitor)-(speaker)-
l resistor l

so is this the arrangement ur talkin abt?

and wut ohm woofers or fullranges should i use?

will the speaker sound good if it has a high resistance? like 15 or 20 ohms on my harman/kardon which has 85rms x 8ohms

cuz over here in india i am not gonna get speakers that are too good in the wattage section and quality section. so like if the speakers has more resistance i think the amplification will be less.

and can u give me the dimensions of the box?

i have leftover 3/4" mdf i used 4 making a sub last week.

its approx 2feet x 4feet sheet.
 
You put a resistor in parallel with the tweeter. Then in series with this tweeter/resistor combination you put a capacitor to roll off the bass and mid. You don't put anything on the woofer.

This is a very crude crossover but will be OK for a starting point.

Hornlovers capacitor value would be OK for 4 inch woofer. You might want to add 2.2 ohms >2W or so in series with the tweeter capacitor though as I think you will find it too bright. I'd also use >4W for the 8.2 ohm resistor.
 
A piezo tweeter doesnt need a cap to protect it, and a lot of people just parallel the piezo with the woofer and use it as is. In my opinion, this makes it sound a bit harsh, since the piezo is working in the midrange, where they dont perform as well as in the higher frequency range. That was the reason for the resistor in parallel with the piezo. This allows the series cap to see a resistive load, and now you can select your capacitor value to roll off the midrange frequencies, allowing the piezo to work in the higher frequencies only. Just one series cap is needed, with its value based on first order crossover formulas (with the series resistor value used as the impedance). This is a very simple way to cut the piezo in at higher frequencies, and as richie))boy pointed out, you may want to attenuate the piezo, depending on the sensitivity of your midrange (or woofer) driver. As for the woofer, you want to make sure it can respond up to the point you choose for your piezo to cut in.
 
ok guys i have bought a 4" woofer and a dome tweeter. they both are local quality dont expect too much.

the woofer looks good as it has a big magnet and have a plastic cone.

my problem is that the tweeter is not sheilded so wut should i do, can i do any modifications so that i can place it on top of a the tv? i have heard a piezo tweeter its toooooooo harsh on the ears it makes ur head ring. so i desided to use a dome tweeter.

the tweeter is i think 4ohm and the woofer is 8ohms i am gonna use 2 such woofers. so do u think i should put everything in series with one capacitor of 2.2uf ? does higher resistance cause any trouble? cuz like is have a really high power amp so i guess high resistance will reduce the amplification right?

so can u tell me the box dimensions i have a 2 x 4 foot mdf piece so wut should be the dimensions 4 the best o/p? so that i can start workin on it?
 
here is a pic of the drivers
 

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ok guys i have bought a 4" woofer and a dome tweeter. they both are local quality dont expect too much.

the woofer looks good as it has a big magnet and have a plastic cone.

my problem is that the tweeter is not sheilded so wut should i do, can i do any modifications so that i can place it on top of a the tv? i have heard a piezo tweeter its toooooooo harsh on the ears it makes ur head ring. so i desided to use a dome tweeter.

the tweeter is i think 4ohm and the woofer is 8ohms i am gonna use 2 such woofers. so do u think i should put everything in series with one capacitor of 2.2uf ? does higher resistance cause any trouble? cuz like is have a really high power amp so i guess high resistance will reduce the amplification right?

so can u tell me the box dimensions i have a 2 x 4 foot mdf piece so wut should be the dimensions 4 the best o/p? so that i can start workin on it?
 
I'd say make a sealed box and the volume will not be critical. First start with the tweeter and driver layout. If you place it on its side then you should consider a 2.5 way crossover. Roll off the midrange on the 2nd midbass driver with a first order filter in the lower midrange at say 200 or 300 Hz.

There will hence be three parts to the crossover - HP to the tweeter, LP to the first woofer and the same LP to the 2nd woofer but with the extra components to roll off the midrange. Such a crossover will have a for of BSC built in. You may wish to experiment with padding the tweeter to taste. This crossover would be quite crude and most probably not well optimised. Crossover point should consider a number of factors, including driver to driver distance with respect to lobing, on and off axis response, power handling implications on the tweeter, harshness that results from crossing too low, poor upper midrange performance of the woofermid where you cross too high and the smoothness of both drivers around the crossover region.

This arrangement will diminish problems with MTMs on the side somewhat. Put the woofers as close as possible to the tweeter. Make the width of the box to suit your preferences - width of TV if under it etc. Make the height so it "looks right" and make the depth to suit pragmatic issues like the depth needed to support TV if its on top. In other words, make it a big sealed box and it should not be critical. Set the centre speaker to small and there will be a HPF to rolloff the bass. Stuff the box to kill internal reflections.
 
hey paul i am really not gettin any clue wut ur talkin abt i cant understand a single word of the technical things ur talkin abt(i am just 17 man) .

so like i am thinkin of puttin the two woofers in series and the tweeter with a series capacitor in parallel to the woofers.( its soundin pretty good when i tested it)
i know its like too amateur 4 u.
but can u tell me somethin better .
best is can u just give me the cross over with a diagram and also with values of the components.
and please cant there be a crossover without that " L1 " cuz like makin those wire wound things is pretty expensive.
 
Space the drivers as woofer-tweeter-woofer horizontally as close together as you can get them. Maybe leave a 5mm gap between them to alow for working tolerances. For the box just make the front about 1.5 to 2 inches bigger than the space this driver configuration takes up. As for the depth, make it about 1.62 times as deep. I'd say you should be aiming for a box of about 7 litres. To work out the volume just multiply the internal width x height x depth. Use millimetres and then divide the result by 1,000,000 and you will have the volume in litres.

For the crossover, wire the woofers in series. See if you can get hold of an L-pad to control the tweeter volume as this will make the crossover design easier.
 
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