Hi, check your plan that you get the SPL capability you are looking for.
I mean, 8" driver cone area is equivalent of roughly two 5" drivers. So, with same excursion it would be capable of roughly few db more output than 5". While distortion, xmax, Pmax, available amplifier power and other aspects probably differ and partly effect max SPL capability you should still make some simple calculations to be sure to get enough improvement. Basically you want to increase system sensitivity. This is not the same as driver datasheet sensitivity, thats what it is at 1kHz and to get that same sensitivity around 80Hz is probably more cone area than you think.
For example, if the genelec you now have sounds bad with the reference level you are listening, it is probably having more than one percent distortion, the the headroom is probably mostly gone, so you'd probably need to increase SPL capability of the system by more than 6db. More like +10db I would reason, roughly the amount of headroom you need. This would mean quadrupling cone area, or perhaps more, roughly 12" woofer. This would dramatically affect the whole system design though, so better design the whole thing from ground up with SPL and bandwidth requirement as starting point.
This is not to critizise, and could contain errors. I see you are concentrating on brands and makes and models of drivers when selecting one is about the last step on a speaker design process so I'm afraid you are lost in details. This is friendly reminder to you to take step back, look the big picture to be sure you are aware and sure about system requirements and that the system you are going to build will deliver what you expect it to.
Have fun!🙂
I mean, 8" driver cone area is equivalent of roughly two 5" drivers. So, with same excursion it would be capable of roughly few db more output than 5". While distortion, xmax, Pmax, available amplifier power and other aspects probably differ and partly effect max SPL capability you should still make some simple calculations to be sure to get enough improvement. Basically you want to increase system sensitivity. This is not the same as driver datasheet sensitivity, thats what it is at 1kHz and to get that same sensitivity around 80Hz is probably more cone area than you think.
For example, if the genelec you now have sounds bad with the reference level you are listening, it is probably having more than one percent distortion, the the headroom is probably mostly gone, so you'd probably need to increase SPL capability of the system by more than 6db. More like +10db I would reason, roughly the amount of headroom you need. This would mean quadrupling cone area, or perhaps more, roughly 12" woofer. This would dramatically affect the whole system design though, so better design the whole thing from ground up with SPL and bandwidth requirement as starting point.
This is not to critizise, and could contain errors. I see you are concentrating on brands and makes and models of drivers when selecting one is about the last step on a speaker design process so I'm afraid you are lost in details. This is friendly reminder to you to take step back, look the big picture to be sure you are aware and sure about system requirements and that the system you are going to build will deliver what you expect it to.
Have fun!🙂
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Thank you for you're insightful comments. I should have been more clear, the Genelecs don't audibly distort at reference levels, none that I can hear anyway, but visually it seems even with a 120hz crossover the 5" drivers are working very hard, and probably introducing a fair amount of IMD. I've modelled the 8" B&C driver, and also a rough model of the ported Genelec, given the B&C is almost double the surface area, and also more than double the available amp power will be available, I have no doubts the 8" will give me the levels I need whilst remaining more composed. The Genelecs don't allow me to cross any lower than 120hz given the volumes I listen at, the 8" should allow me to have more room for experimentation in the 80-120hz crossover region too!
Cool, as long as you are sure its meeting your target its fine 🙂
Another example for fun as I had the simulator open 😀 here various B&C NDL drivers ranging 5-15" plotted in closed enclosure automatically calculated by the simulator per TS params for 1W input power.
In general the (max) output down low is just volume displacement. If you had 100W amplifier, then system sensitivity at your target frequency defines the max SPL capability because max output would be limited by the amplifier. Bigger drivers can usually take more power before heat issues so max output grows more with bigger drivers. If you had unlimited amplifier power available bigger drivers have loads more output capability than smaller ones, which would apply here as well. 8" accompanied by heftier power amp might be plenty enough improvement.
On these particular driver models the 8" is ~6db more sensitive at 80Hz than the 5" . Enclosure is four times bigger though. If you put the 5" to the 8" enclosure it gains few db more sensitivity but max SPL would still be limited by xmax, max volume displacement, it would just take less power in the bigger enclosure.
Another example for fun as I had the simulator open 😀 here various B&C NDL drivers ranging 5-15" plotted in closed enclosure automatically calculated by the simulator per TS params for 1W input power.
In general the (max) output down low is just volume displacement. If you had 100W amplifier, then system sensitivity at your target frequency defines the max SPL capability because max output would be limited by the amplifier. Bigger drivers can usually take more power before heat issues so max output grows more with bigger drivers. If you had unlimited amplifier power available bigger drivers have loads more output capability than smaller ones, which would apply here as well. 8" accompanied by heftier power amp might be plenty enough improvement.
On these particular driver models the 8" is ~6db more sensitive at 80Hz than the 5" . Enclosure is four times bigger though. If you put the 5" to the 8" enclosure it gains few db more sensitivity but max SPL would still be limited by xmax, max volume displacement, it would just take less power in the bigger enclosure.
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Another quick remark: make sure the cabinet is made well so there is no resonances, no port noise if you intend to put one, also keep attention to the tweeter crossover so that its not too low/shallow. All this is to ensure the SPL capability is not limited by some annoyance and you actually get more (good sounding) output than with the reference you have.
Looking at DXT datasheet the sensitivity on-axis EQ:d flat is around 86db, so the 10NDL woofer would match that at 80Hz but that would drag xo too low for the tweeter, or directivity issue that the genelec doesn't have, both of which are lessor performance than what the genelec has. So, perhaps the 8" is nice woofer to to use with the dome tweeter, perhaps use steep xo, so perhaps the sound could be good louder than the genelec.
Just thinkin out loud 😀 Have fun!
Looking at DXT datasheet the sensitivity on-axis EQ:d flat is around 86db, so the 10NDL woofer would match that at 80Hz but that would drag xo too low for the tweeter, or directivity issue that the genelec doesn't have, both of which are lessor performance than what the genelec has. So, perhaps the 8" is nice woofer to to use with the dome tweeter, perhaps use steep xo, so perhaps the sound could be good louder than the genelec.
Just thinkin out loud 😀 Have fun!
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My orginial plan was to buy some Genelec 8350's and retire the 8030'cs to surrounds, but I figured I could probably get better performance for less money going this route. Each DIY speaker should be roughly £700 which is only slighltly more than the price of the 8030c, and more than half the price of the 8350.
The 8" closed box route should also work better for integration within my existing system too, and also gives me the opportunity to develop the surrounds at a later date based on the same SB26 tweeter but maybe a 5" or 6" waveguide!
The 8" closed box route should also work better for integration within my existing system too, and also gives me the opportunity to develop the surrounds at a later date based on the same SB26 tweeter but maybe a 5" or 6" waveguide!
Do you need a short listenning distance or a more classic midfield one ? That dictates also your choices....
Just to update this thread, I built the 2-way using BC 8NDL51 and 8" somasonus WG with SB26ADC optimised with VituixCad, I couldn't be happier with the sound. As detailed but more dynamic than Genelec 8030c, way more output and only £200 or so more expensive, not counting the hours spent designing measuring etc. Atm its still a prototype, and I intend on going CLD with the box and of course a nicer printed waveguide.
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Thank you! I briefly tried an LR8 crossover which tidied up the directivity a little but didn’t sound as good to my ears. My original goal was to get close to the performance of the Genelec 8050 and I think I’ve achieved that!
Can the BC 8NDL51 do an acoustic LR2? Try it you might just find it's improves the PIR and power response around 2-3Khz.😉
I’ve tried LR2, LR4 and LR8. No matter what I did LR2 sounded awful and looked even worse, LR8 smoothed out the directivity peak and power response a little but for some reason sounded worse than the LR4 which I’ve settled on for now. The PR peak at 2-3khz is only around 1.5-2db and isn’t too audible.
The above are just active XO simulations. My first simulation at 1800hz using ViutixCad was re-measured outdoors and was almost identical to the sim, I still need to go out again and remeasure this one.
For a crossover at 1800Hz you don't really have to go outdoors IMHO. I think the off-axis bump beginning at 2k is baffle-related.
The crossover is at 1200hz, it’s either baffle related or waveguide related, either way it isn’t audible, but the next box will have larger round overs.
To me, it looks like a calibration error in one of the mics... Are you using a calibration file? Be certain that you are using the Umik calibration with Umik, and the EMM6 calibration with the EMM6...