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Keswick 11th October 2012 03:48 AM

Need help designing speakers
Hi all, can anyone help with designing a pair of speakers for some drivers I bought on sale. I don't have the computer skills or knowledge for designing speakers with multiple drivers and would like to do a TQWP if possible. I have spent many frustrating hours going nowhere so any assistance or ideas would be greatly appreciated. Adrian.
All drivers are Vifa and some of the parameters given for the 10 and 12 inch woofers are suspicious, Sd for 10 inch was calculated from 12 inch.

12 inch cs-2353 dual 4 ohm coils connected as 8 ohm
Fs 36
Qts 0.43
Qes 0.48
Vas 61
Cms 187.3
Sd 452
Spl 88
Re 7.2

10 inch cs2351 dual 4 ohm voice coils connected as 8 ohm
Fs 38.6
Qts 0.37
Qes 0.42
Qms 3.27
Vas 54
Cms 310.3
Sd 348.4
Spl 87
Re 7.2

6.5 inch midbass P17WJ 8 ohm
Fs 37
Qts 0.35
Qes 0.45
Qms 1.55
Vas 34.7
Sd 136
Spl 88
Re 5.8

Aluminium dome tweeter with wave guide 6 ohm

picowallspeaker 11th October 2012 04:56 AM

I would stick to the 6.5" & tweeter only.

system7 11th October 2012 05:42 AM

I'd agree with picowallspeaker here. The Vifa P17WJ is a nice flat response polycone that is easy to work with.

Since your new to this, I'd commend Audio Legend Marshall Leach's simple design here:
Vifa 2-Way Loudspeaker System

You should be able to adjust the attenuator to work with almost any tweeter. Expect a metal tweeter to sound a bit, er, metallic, but should be OK. :D

picowallspeaker 11th October 2012 06:18 AM

Well, er.. Thx System 7 ! maybe ... (there's still an invitation pending
for you if you are visiting Florence, someday ..)
The waveguide would put in the game some gain, so there might be
a too strong emission; if the tweeter is sufficiently robust, a simple first order
(just a capacitor) would work . I fear that too much attenuation would kill
the dynamics.
But that is left to the considerations of the User, so the power flowing thru the
components has to be valued in correspondence to the style of listening :confused: The port should be placed on the rear side ....
For the inevitable subwoofer to follow :rolleyes::p
I would build a four channel amplifier , each to drive a single coil .
An electronic crossover to cut the frequencies > 60-100 Hz .
The high-pass filter for the satellites can be done by changing the value of the input capacitor of the relative amplifier. It will be first order ( -6 dB/oct )and
the acoustic transition from sub to sat would be still at 6 dB/oct.

A TQWT would have a length of -I fear, again !- of about 3 m .
That's similar to my next project ,but thinking to leave the mid-wf
with no baffle and no box .;)

system7 11th October 2012 06:32 AM

1 Attachment(s)
Ah, Firenze, scene of the Renaissance! I would very much like to revisit! Thankyou. :D

The frequency response of the Vifa P17WJ (below) is very nice, if a little bass light, but no bad thing in a small room IMO.

I liked Marshall Leach's design, being quite KEF Coda IIRC. Easily tuned. :cool:

balerit 11th October 2012 07:01 AM

TQWP speakers are great, check mine:

DIY Tapered Quarter Wave Pipe (TQWP) Voigt loudspeaker - The Book Worm


Keswick 11th October 2012 08:08 AM

Thank you to all who have replied, it seems most suggestions lean towards building speakers with the tweeter and midbass and a seperate subwoofer.This certainly gives me somewhere to go if I can't use all drivers in the one box but I would still prefer to do it that way.I should explain that I have a subwoofer amp for the bass speakers so am really trying to build a two way speaker with subwoofers built in. Not too concered about size within reason. Thanks again, Adrian.

Keswick 11th October 2012 09:30 AM

Also, I need to use 6.5 inch driver as a midbass only as it wont handle amps power. I chose the tweeter based on reviews claiming it wasn't too metalic in sound, unfortunately it needs a 2nd order crossover for power handling.

Dissi 11th October 2012 11:18 AM

If you want to use all the drivers, the result will be a 4-way having very large dimensions. The 10" from 150-200 Hz to 600-800 Hz and the P17 as midrange. Maybe a 3 1/2-way would be an option.

mondogenerator 11th October 2012 12:42 PM

I dont want to be the pessimist, but i dont see the point in going beyond a 3way using either the 10 or 12. Plenty of BSC correction should be possible with either sub, so whats the point of a 3.5way? Go for an established design and mod filter to suit, as System7 suggested. Just my opinion.

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