Need help designing speakers

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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
Qms3.73
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
 
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 .;)
 
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:
 

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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.
 
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.
 
I will be using a powerfull subwoofer amp that needs 8 ohms, the four subwoofer speakers are a cheap way of dealing with the power and giving 8 ohms impedance. All 4 would be for the same range. The only way I can use 2 is to power them off the receiver with the other speakers and go without sub amp. I'm starting to think large subwoofer and small satellites. Adrian.
 
Hi Adrian, just following this up from your other thread. I reckon a good sub (or subs) and satellites makes a lot of sense. Now, re; the tweeter: around 3-4k Hz cross over will be fine but it must be 2nd order (or higher). The nice thing about second order networks is that the inductor (coil) crosses the tweeter after the capacitor and that helps suppress the natural resonance peak and also also reduces the interaction of the impedance at resonance and the capacitor. So they are a good and "user friendly" circuit. They are also more tolerant of the variations in values and cheap to build. No doubt you'll read more later and realise that cross overs are a very complex and controversial area...........as you are probably realizing by now, this comment applies to almost ALL areas discussed on this forum....acoustics is still a black art to some extent.
Btw do you actually live near Keswick? I am Victorian originally (Benalla, Melb' etc) but been up here 15 yrs.
Cheers, Jonathan
 
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diyAudio Member
Joined 2007
Keswick give a link to those Vifa drivers please.
I can't seem to find them Googling.
Also I find it hard to understand a sub amp that actually needs an 8 ohm load to work.
Absolutely nothing wrong with going 3-way using the P17 in a small sealed box as a high power mid.
Combination of the P-17 and the D-26 is a classic choice and there are many successful designs out there
 
Hi,

Regarding the Leach design :

" The crossover frequency for the woofer was chosen experimentally
for optimum frequency response with the tweeter."
And :
" A L-pad is used to attenuate the signal to the tweeter by about 4 dB
to equalize the on-axis pressure sensitivities of the two drivers. "

Is completely the cart before the horse, and a poor no BSC design.

rgds, sreten.
 
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Just another Moderator
Joined 2003
Paid Member
Hi Sreten, I'm curious because I see you post about no BSC designs often, but I want to know exactly what you mean by it.

1. there is no obvious BSC compensation circuitry in the crossover

or

2. you can tell by looking at the crossover that does not have any compensation at all and the speaker will have thin bass.

I'm assuming 2, but wanted to be sure. As I'm pretty sure you know that there are ways other than putting in a "text book" BSC circuit to achieve the same result.

I Wouldn't be able to tell from the leach schematic alone, I'd have to simulate to see, but one of the simpler methods of dealing with BSC is to use a bigger coil on the woofer and pad the tweeter down more, obviously how well this works will depend on the individual design.

My own MTM project does not have any specific BSC circuitry but the end result is a flat response down to 200Hz which was the design goal (200Hz is where they naturally start rolling off). The original crossover had no BSC compensation at all (as I was intending to do it passively at line level) but when I decided to redo the crossover, the BSC came along for a free ride ;)

Tony.
 
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Hi Adrian, just following this up from your other thread. I reckon a good sub (or subs) and satellites makes a lot of sense. Now, re; the tweeter: around 3-4k Hz cross over will be fine but it must be 2nd order (or higher). The nice thing about second order networks is that the inductor (coil) crosses the tweeter after the capacitor and that helps suppress the natural resonance peak and also also reduces the interaction of the impedance at resonance and the capacitor. So they are a good and "user friendly" circuit. They are also more tolerant of the variations in values and cheap to build. No doubt you'll read more later and realise that cross overs are a very complex and controversial area...........as you are probably realizing by now, this comment applies to almost ALL areas discussed on this forum....acoustics is still a black art to some extent.
Btw do you actually live near Keswick? I am Victorian originally (Benalla, Melb' etc) but been up here 15 yrs.
Cheers, Jonathan

Hi, 2nd order is the limit of my knowledge and also the recommended order for this tweeter. I was thinking of trying a first order for the 6.5 inch mid, haven't look into it too much yet, not sure if I'll build 3 way or sub and satellites. I used to work on an Island off the coast of Mackay called Keswick, my name was taken so I used it till I can come up with something better. Cheers, Adrian.
 
Why? with a 'decent' quality 12" woofer would you even want, let alone Need a Sub? Odd indeed.
Personally, I find nothing quite as ridiculous as a wee speaker box that then requires a Stand.. invariably complex/substantial and expensive.
No need to mention fugly, just to add insult to injury.
 
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