I've noticed that some coaxial 2 way speakers have very good performance and come with a proprietary metal back can which is very deep. These back cans come with some sort of polyester fibre fill in them. It looks like the stuff they use in pillows and cushions. I'm sure this is possible to get at an upholstery shop.
Hoping some experienced speaker building enthusiasts can help me. I want to build wooden boxes for these coaxial speakers with the objective of reducing their depth but preserving their sound signature. Hence, I have some questions:-
Attached is an example of a coaxial speaker and metal back can.
Any input and help will be appreciated. I'm sure fellow members have tried this.
Hoping some experienced speaker building enthusiasts can help me. I want to build wooden boxes for these coaxial speakers with the objective of reducing their depth but preserving their sound signature. Hence, I have some questions:-
- Do I calculate the volumetric area of the back can and preserve that volumetric specification when calculating the box size?
- Is the volumetric specification important or is it ok for me to exceed the volumetric specification a bit as long as all the speaker boxes are built the same?
- How do apply the polyester fill and hold it to the back? - I'm thinking of incorporating a wire mesh to hold the fibre to the back surface.
- I would just incorporate speaker wire terminals at the back of the box, air-tight them with silicon. Is that a good approach?
- I'd love to achieve a final depth of between 4" to 6". I presume this is enough to accommodate for the woofer driver excursion.
Attached is an example of a coaxial speaker and metal back can.
Any input and help will be appreciated. I'm sure fellow members have tried this.
Attachments
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Could you not use a coax without the can and build a regular box in the shape you want? Is that really a woofer and tweeter or a mid and tweeter? Looks like the can is the box for the larger cone
Smaller, regularly shaped enclosures have their internal modes starting at a higher frequency. This shouldn't be a concern if you stuff, although for example, with horn enclosures this is a reason not to go larger since stuffing would normally be avoided there.
If you plan to cross these to a woofer, the precise volume matters less.
If you plan to cross these to a woofer, the precise volume matters less.
Hi Randy, thank you so much for your response. That is exactly what I intend to do, the can is detachable and I want to build a regular box. The shape can be sensible rectangular or square with the coax driver centralised.
It's a mid and tweeter, with the back can or wooden box it would achieve from 70Hz to 20kHz.
I suppose building a regular box should not be too difficult but I wanted input from fellow members that have gone down this path just to get insight.
It's a mid and tweeter, with the back can or wooden box it would achieve from 70Hz to 20kHz.
I suppose building a regular box should not be too difficult but I wanted input from fellow members that have gone down this path just to get insight.
@AllenB - Thank you for your input. Yes, I plan to cross these to a subwoofer.
Thank you for pointing out the 'Volumetric' aspect. Is there a good practise based approach to it?
I presume it's best to either match or increase the volume of the box a little for optimal performance.
What if you built a test box. And then measured the sound output with the can as a baseline. Then measure the box. Change fill quantity and arrangement. Change box volume using blocks of XPS foam. See if the new results better the can?
Or machine the can volume from a block or layered slabs of wood for a wooden can of any shape?
Or machine the can volume from a block or layered slabs of wood for a wooden can of any shape?
Maybe. It helps to know what result you want.
Perhaps you can use some simulation software such as hornresp in order to determine which direction would improve your drive power requirements.
Changes like this are sometimes done to relax the response and impedance peak to improve crossover implementation. Of course, it tends to come down to the response you need. Have you determined the properties of the current response rolloff?
The can is optional, the "sound signature" (the frequency response) depends on the enclosure size.
The IC95 speaker is only 87dB 1w/1m (4 0hm, 2.83v 90dB), it will max out at ~109 dB one meter (at a bit over it's 150 watt rating), 103dB at 2 meters, pretty light for "home theatre".
The the cone size with surround is ~5.5", it would probably exceed Xmax ~106 dB 1meter at 100 Hz, under 100dB ~70 Hz (94dB at 2meters).
Making the enclosure larger will allow the cone more excursion with less power.
The IC95 co-ax is based on the 6.5-inch mid-woofer used in the MPS1620P, which uses a 12.6" x 8.3" x 11.6" (external dimensions) box that can be operated sealed or ported.
Simply stapling it in place works, or stapling a breathable fabric in between the fill and driver if you are concerned about migrating particles.
The speaker terminals should be reasonably air tight to avoid whistling noises.
The woofer excursion is limited by it's (tiny) surround, not by box depth.
The IC95 speaker and crossover is designed for flush ceiling or wall mount, so a wide, flatish box would work best.
The swiveling tweeter is a cute feature to point at the listening position when the woofer isn't.
Thank you everyone for your kind input.
@weltersys - what a clear and comprehensive response. As you rightly mentioned, judging from the sensitivity, this coax driver may not be ideal for home theatre. Do you know of any other third party coaxial drivers that are high performance, built for DIY and reasonably priced?
@weltersys - what a clear and comprehensive response. As you rightly mentioned, judging from the sensitivity, this coax driver may not be ideal for home theatre. Do you know of any other third party coaxial drivers that are high performance, built for DIY and reasonably priced?
https://loudspeakerdatabase.com/search/type=Coaxial/5.0≤size_in≤12.0
For HT with high spl capacity I'd look for 8-12"
Some pro coaxials come without the tweeter/compression driver. Being coaxial does't prove that it will have wide and smooth dispersion.
For HT with high spl capacity I'd look for 8-12"
Some pro coaxials come without the tweeter/compression driver. Being coaxial does't prove that it will have wide and smooth dispersion.
B&C has co-ax available for most any SPL and dispersion you might want, and also offers passive crossovers suitable for some of the models.
I agree with Juhazi's size recommendations.
