Hi everyone. So having built a few full range speakers including the famous Ikea salad bowl speakers with MA 10.2 drivers, I feel ready to tackle a multiway.
So my plan is a fully active three way project in as small a form factor as possible (for WAF obviously!)
So I have planned a sealed three way based on these drivers:
Tweeter:
SB Acoustics SB29RDNC
Mid-range:
Scanspeak Illuminator 12MU 8731T00
Woofer:
Scanspeak Classic 21W 8555.00
Crossover points 300hz and 3000hz. I calculate in a 31 L sealed box the scanspeak classic should reach an F3 of 45 hz, which is fine as I have subs to take up the slack below this point.
All three drivers seem very well behaved around these crossover points and the polar response from the data sheets should be very even through the crossover regions too.
I am planing on basing it on the Wilmslow Audio HSM cabinet with a custom cut baffle, which has a total volume of 33 liters, allowing me to seal the mid-range with a 1.5L volume tube and maintain the 31 ish internal volume for the woofer.
See drawing below for baffle layout:
Any thoughts before I start!?
PS baffle width is 270mm
So my plan is a fully active three way project in as small a form factor as possible (for WAF obviously!)
So I have planned a sealed three way based on these drivers:
Tweeter:
SB Acoustics SB29RDNC
Mid-range:
Scanspeak Illuminator 12MU 8731T00
Woofer:
Scanspeak Classic 21W 8555.00
Crossover points 300hz and 3000hz. I calculate in a 31 L sealed box the scanspeak classic should reach an F3 of 45 hz, which is fine as I have subs to take up the slack below this point.
All three drivers seem very well behaved around these crossover points and the polar response from the data sheets should be very even through the crossover regions too.
I am planing on basing it on the Wilmslow Audio HSM cabinet with a custom cut baffle, which has a total volume of 33 liters, allowing me to seal the mid-range with a 1.5L volume tube and maintain the 31 ish internal volume for the woofer.
See drawing below for baffle layout:
An externally hosted image should be here but it was not working when we last tested it.
Any thoughts before I start!?
PS baffle width is 270mm
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sb23 8" woofer could be the alternative.
as for tweeter, i would prefer smaller dome, 19-25mm to have better dispersion, u wont need big tweeter for xo at 3khz.
as for tweeter, i would prefer smaller dome, 19-25mm to have better dispersion, u wont need big tweeter for xo at 3khz.
Thanks for the input! The SB23 is a nice driver and a little cheaper, but sims at approx 38 liters for an F3 of 50hz, so a little too large and not as deep.
The SB29, is very low distortion and has some of the best off axis response I could find looking through the data sheets - even when comparing to smaller domes - I couldn't find a better dispersing tweeter with such a small diameter faceplate and low distortion - unless you have any suggestions?
Thanks again
The SB29, is very low distortion and has some of the best off axis response I could find looking through the data sheets - even when comparing to smaller domes - I couldn't find a better dispersing tweeter with such a small diameter faceplate and low distortion - unless you have any suggestions?
Thanks again
Since your midrange and woofers are Scanspeak quality, you should do the same for the tweeter. Measurements/Datasheets only tell part of the story. For superior dispersion, low distortion and dynamics, go for the Scanspeak D2904/7100.
That is an excellent suggestion, but at a x-over point of 3k ish, I would be worried about the C-C spacing given it has a 104mm faceplate?
One of the reasons for selecting the SB29 is the small flange diameter. Looking at the small diameter neo scanspeak tweeters - they don't seem to measure as well as the SB29 - looking at Zaphs's site too.
Any other suggestions with a smaller diameter?
Thanks.
One of the reasons for selecting the SB29 is the small flange diameter. Looking at the small diameter neo scanspeak tweeters - they don't seem to measure as well as the SB29 - looking at Zaphs's site too.
Any other suggestions with a smaller diameter?
Thanks.
Have a think about offsetting the tweeter from centre.
There is a useful programme "The Edge" that can model edge diffraction so you can hopefully minimise this a bit.
Frank
There is a useful programme "The Edge" that can model edge diffraction so you can hopefully minimise this a bit.
Frank
I'd suggest using a waveguide for the tweeter to limit its dispersion and give a smoother transition to the mid which will be beaming about 90deg at 3k.
A wide-dispersion tweeter is only any good if the mid has an equally wide dispersion at the xover frequency which this one does not have.
Here is a nice example for the SB29:
acoustic waveguides
You might need to scroll down a bit.
A wide-dispersion tweeter is only any good if the mid has an equally wide dispersion at the xover frequency which this one does not have.
Here is a nice example for the SB29:
acoustic waveguides
You might need to scroll down a bit.
Thanks guys - more great advice! Rather than a separate waveguide.....what about the 27TBCD/GB-DXT?
This would seem to match the dispersion of the mid better around the crossover and is also a low distortion tweeter.
PS - that 'edge' program is fascinating. Playing around with it, at my crossover points, it seems the current driver placement is a reasonable compromise!
This would seem to match the dispersion of the mid better around the crossover and is also a low distortion tweeter.
PS - that 'edge' program is fascinating. Playing around with it, at my crossover points, it seems the current driver placement is a reasonable compromise!
i use sb satori and raal 70-10 with 2800hz xo, it has almost
even dispersion until 45deg.
u can use almost any dome tweeters at 3khz, u can choose the ones with the closest sensitivity to your midrange and spl capability, but with modern tweeters, almost any of them wont fail before your midrange does.
even dispersion until 45deg.
u can use almost any dome tweeters at 3khz, u can choose the ones with the closest sensitivity to your midrange and spl capability, but with modern tweeters, almost any of them wont fail before your midrange does.
OK so if I go with a wave guide tweeter combo, I'd be swapping flat freq response (unless I eq it flat) for more uniform polar response (as it seems you can't have both, and a waveguide usually results in some upper end droop) - would this be a fair summary?
If so - I really don't want to get into eq if possible - I was hoping for flat freq responses that would require minimal crossover complication - in fact I was hoping for straight forward LR4 crossovers at 300 and 3000hz without too much else!
I suppose if I dropped the upper x-over to 2.5khz, this might help even the power repsonse a little?
If so - I really don't want to get into eq if possible - I was hoping for flat freq responses that would require minimal crossover complication - in fact I was hoping for straight forward LR4 crossovers at 300 and 3000hz without too much else!
I suppose if I dropped the upper x-over to 2.5khz, this might help even the power repsonse a little?
The waveguide also reduces distortion and usually one cap is enough to get the frequency response back into line. Have a look at this thread:
http://www.diyaudio.com/forums/multi-way/241286-my-first-wave-guide-speaker-lots-pics.html
That said if I remember correctly the Scanspeak D2908 can be used without any eq'ing cap and it is a very low distortion tweeter to start with.
On Dave Pellegrenes site is a link to all the measured response curves.
http://www.diyaudio.com/forums/multi-way/241286-my-first-wave-guide-speaker-lots-pics.html
That said if I remember correctly the Scanspeak D2908 can be used without any eq'ing cap and it is a very low distortion tweeter to start with.
On Dave Pellegrenes site is a link to all the measured response curves.
Hi, the D2904 can be crossed as low as 1500Hz LR4 so this gives you flexibility in tuning the crossover points. The Morel Supreme ST728 tweeter seems like a great 72mm faceplate tweeter.
In my experience, the larger faceplate/larger rear chambered tweeters always sound better than the smaller ones.
Waveguide are great too, but they give a more focused sound compared to the more diffuse sound of non waveguide. Pick your poison.
OK! Back to the drawing board on this one! Lots to think about - thanks for your input guys...I'm gonna look at waveguides etc for a bit. Cheers.
OK! Thought about this some more. I thought I should explain why I have settled on this design...I have taken inspiration from the SP1M monitor which received amazing reviews in the pro-audio world.
SP Acoustics SP1M
That has the same mid-range driver, similar C-C spacing/baffle driver alignment, similar crossover points and is also a sealed design.
It uses 'ceramic/MDF' cabinet walls - thin ceramic tiles glued internally to the MDF walls - this combination of brittle ceramic/viscous glue/MDF layering greatly reduces resonance and keeps things inert.
All the info I have read on sealed cabinet design states that as long as it is inert and well stuffed - say 1.5lb of fibreglass per cubic foot - ish, then it doesn't require any internal fancy reflecting/refracting surface designs, though it can't hurt to have dimensions close to the golden ratio. So, I think my cabinet design should be up to spec, if I glue tiles to the internal surfaces with green glue, and ensure it is carefully stuffed in the right places.
Loading the expensive mid-range with a 2 litre stuffed cylinder - perhaps with an irregularly surfaced wooden end cap to prevent internal reflections and standing waves, should again be close to ideal looking at the datasheets and what others have tried with this high end driver (madisound recommends a 2 litre sealed enclosure for it).
So then it just comes down to tweeter choice and picking polar response versus freq response etc. smaller dome, versus larger domes, versus waveguides. Although as already pointed out when crossing fairly high, most tweeters will sound good, and this is probably more about personal preference.
Amplifier choice will be from the pro-audio world and probably fairly high watts - probably 300, 200, 100 for W/M/T for instance. I think the crown amplifiers are excellent. As said, I hope to keep the crossovers fairly simple but that will depend on measurements.
SP Acoustics SP1M
That has the same mid-range driver, similar C-C spacing/baffle driver alignment, similar crossover points and is also a sealed design.
It uses 'ceramic/MDF' cabinet walls - thin ceramic tiles glued internally to the MDF walls - this combination of brittle ceramic/viscous glue/MDF layering greatly reduces resonance and keeps things inert.
All the info I have read on sealed cabinet design states that as long as it is inert and well stuffed - say 1.5lb of fibreglass per cubic foot - ish, then it doesn't require any internal fancy reflecting/refracting surface designs, though it can't hurt to have dimensions close to the golden ratio. So, I think my cabinet design should be up to spec, if I glue tiles to the internal surfaces with green glue, and ensure it is carefully stuffed in the right places.
Loading the expensive mid-range with a 2 litre stuffed cylinder - perhaps with an irregularly surfaced wooden end cap to prevent internal reflections and standing waves, should again be close to ideal looking at the datasheets and what others have tried with this high end driver (madisound recommends a 2 litre sealed enclosure for it).
So then it just comes down to tweeter choice and picking polar response versus freq response etc. smaller dome, versus larger domes, versus waveguides. Although as already pointed out when crossing fairly high, most tweeters will sound good, and this is probably more about personal preference.
Amplifier choice will be from the pro-audio world and probably fairly high watts - probably 300, 200, 100 for W/M/T for instance. I think the crown amplifiers are excellent. As said, I hope to keep the crossovers fairly simple but that will depend on measurements.
why such a small woofer? Do you plan on using subs? why not something like a 12 inch of a 15 inch on the bottom?
Think about this maybe somewhat silly approach😉
You don't need 21W as bass player at all, just build a small
box for 12MU and tweeter and cross it at 100 Hz with
yours subs. If in any doubt, pick bass-mid driver to
replace 12MU and cross it with subs around 50 Hz or so.
Form factor you are seeking and joy for your darling
guaranteed.
A very good suggestion, I'll admit 😛
But my subs are located in various places around the room, and I like using the Geddes approach to bass below 100hz - multiple locations - at preferably 4, so I currently have two studio monitors (focal CMS65) and two subs (BK 200) which load the room very evenly below 50 hz down to approx 25 hz.
My wife will allow me the subs as they are hidden from view!, and the two monitors are OK - but floor standers would be too large. This seemed a nice way of keeping the smaller box, sealed design, with F3 at or below 45hz (same as my current focal monitors). As I am planning on putting the speakers very close to the front wall I will get room gain as well, which should help them drop quite low in the room.
But my subs are located in various places around the room, and I like using the Geddes approach to bass below 100hz - multiple locations - at preferably 4, so I currently have two studio monitors (focal CMS65) and two subs (BK 200) which load the room very evenly below 50 hz down to approx 25 hz.
My wife will allow me the subs as they are hidden from view!, and the two monitors are OK - but floor standers would be too large. This seemed a nice way of keeping the smaller box, sealed design, with F3 at or below 45hz (same as my current focal monitors). As I am planning on putting the speakers very close to the front wall I will get room gain as well, which should help them drop quite low in the room.
Do you have measurement capability/crossover simulation capability like SoundEasy? If you're going to spend that kind of money on drivers....without it you'll never get the most out of them.....
So true. I will do soon!!
Either that, or a beringher DSP x-over, or possibly a DEQX.......this part I am still debating about.
Either that, or a beringher DSP x-over, or possibly a DEQX.......this part I am still debating about.
Even with a DSP xover, without the ability to look at what you're doing frequency response wise...you'll be operating kind of blind. It'd be like hitting a golf ball to a putting green without a flag on it. You know the area you're supposed to be in, but not if it's right.
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