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-   -   Need help designing speakers (http://www.diyaudio.com/forums/multi-way/221337-help-designing-speakers.html)

Dissi 11th October 2012 01:32 PM

I agree, I only referred to Keswick's wish to use all drivers. I wouldn't do it either. The 10" and 12" are to close together.

Keswick 11th October 2012 02:48 PM

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.

Jonathan Bright 18th October 2012 09:36 PM

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

Moondog55 18th October 2012 10:47 PM

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

Moondog55 18th October 2012 11:55 PM

OK I found the data except for X-max which my box programs need. Forget the jaycar designs, they are for cars where the only thing people seem to be looking for is maximum SPL. What works in a car doesn't normally work well in the house

sreten 18th October 2012 11:56 PM

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.

Dissi 19th October 2012 12:48 AM

1 Attachment(s)
Attachment 307215

wintermute 19th October 2012 02:35 AM

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.

Keswick 19th October 2012 04:06 AM

Quote:

Originally Posted by Jonathan Bright (http://www.diyaudio.com/forums/multi-way/221337-help-designing-speakers-post3206748.html#post3206748)
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.

Bare 19th October 2012 04:59 PM

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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