I already settled on
Sub bass 4x B&C 18tbw100
Bass p audio 15BM500
Tweeter ESS Heil AMT (or possibly nd3st compression driver. I have both and will try both)
But I have trouble settling on a midrange. My choice for 1st order filters is a challenge, especially combined with high SPL. Range will be 400-2000hz or 500-2500hz
Crossovers are DSP
Which of these would you choose and why?
Sub bass 4x B&C 18tbw100
Bass p audio 15BM500
Tweeter ESS Heil AMT (or possibly nd3st compression driver. I have both and will try both)
But I have trouble settling on a midrange. My choice for 1st order filters is a challenge, especially combined with high SPL. Range will be 400-2000hz or 500-2500hz
Crossovers are DSP
Which of these would you choose and why?
I'm too lazy to resize the frequency response plots so both axes are on similar scales between them all. Off-axis behavior and general misbehavior around your upper cross point being primary concerns. With a 6 dB/octave crossover, you need quite a bit of good behavior beyond the cross point.
Indeed, ideally need > -35 dB to get down to our noise floor, though folks generally do fine @ -24 dB = 400/2^4 = 25 Hz and 2500*2^4 = 40 kHz
Like the pioneers, I always want(ed) the highest efficiency, so can shelve down to get max available dynamic headroom @ lowest power, distortion, etc..
Like the pioneers, I always want(ed) the highest efficiency, so can shelve down to get max available dynamic headroom @ lowest power, distortion, etc..
B&C 8pe21……..you need that smooth function rolloff adding 1st order filter…..you’ll end up with a 3rd order acoustic
I feel the 8pe21 doesn't have enough top end extension for a 2 or 2.5k crossover. It peters out around 4.5khz. ideally I want two octaves overlap so a driver that reaches 8 or ideally 10khz
You’re not taking into account directivity of the mid driver…….you can’t mismatch at the crossover point with an OB speaker. You’d start rolling off the 8pe21 at 1k where it begins to beam……..that will give you your 2 octaves.
There’s also tonal balance and timbre to consider……the old way of ‘voicing’ a speaker…….something sighted listening with measurements lead to extreme bias…..your eye/ brain mechanism prioritizing everything. As a recording. And live engineer for nearly 4 decades, I’ve come to appreciate voicing as a top priority. Breaking up the 500hz to 3k region with two drivers is a serious compromise to phase and time alignment….imaging suffers greatly as does fine detail due to the phase overlapping. This region is where nearly all of the fundamental notes exist. I’ve found that understanding these same fundamentals in the source just as important as the speaker……..the primary reason why ATC monitors are so highly regarded and have produced some of greatest recordings available.
The common 2 way bookshelf speaker is a great example…….when done properly, the listener gets a good performance……..nothing great……just good most of the time with most recordings……even the bad ones of great songs as all of the phase errors within the recording get all mixed up within the crossover region. But these same systems can never reveal what exists in a truly great recording.
While the 8pe21 is marketed as an 8” driver, it’s relatively wide surround and cone rib give it the directivity index of a 6” driver……one of the reasons it’s so highly regarded as one of the best midrange drivers ever…….it can play low and clean with extreme efficiency. That at due to the low qts it’s perfect for horn loading in a professional application.
Since you’re clearly investing so much $$$ and time on this, I’d purchase one and mount it on a suitable baffle and just listen to it…….no shaping of any kind…..just listen to what it can do. If you don’t care for it (highly unlikely) you can easily sell it off and recover most of your investment…….a very small price to pay given the overall investment in perfection.
There’s also tonal balance and timbre to consider……the old way of ‘voicing’ a speaker…….something sighted listening with measurements lead to extreme bias…..your eye/ brain mechanism prioritizing everything. As a recording. And live engineer for nearly 4 decades, I’ve come to appreciate voicing as a top priority. Breaking up the 500hz to 3k region with two drivers is a serious compromise to phase and time alignment….imaging suffers greatly as does fine detail due to the phase overlapping. This region is where nearly all of the fundamental notes exist. I’ve found that understanding these same fundamentals in the source just as important as the speaker……..the primary reason why ATC monitors are so highly regarded and have produced some of greatest recordings available.
The common 2 way bookshelf speaker is a great example…….when done properly, the listener gets a good performance……..nothing great……just good most of the time with most recordings……even the bad ones of great songs as all of the phase errors within the recording get all mixed up within the crossover region. But these same systems can never reveal what exists in a truly great recording.
While the 8pe21 is marketed as an 8” driver, it’s relatively wide surround and cone rib give it the directivity index of a 6” driver……one of the reasons it’s so highly regarded as one of the best midrange drivers ever…….it can play low and clean with extreme efficiency. That at due to the low qts it’s perfect for horn loading in a professional application.
Since you’re clearly investing so much $$$ and time on this, I’d purchase one and mount it on a suitable baffle and just listen to it…….no shaping of any kind…..just listen to what it can do. If you don’t care for it (highly unlikely) you can easily sell it off and recover most of your investment…….a very small price to pay given the overall investment in perfection.
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NOT the Dayton. It has some FR problems above 1kHz. The datasheet FR plot only hints at these, IME when I measured one they were worse (peaks and dips). Too bad, it's a good driver below 1kHz but that is a little to low to cross over, esp. first order.
I am still not sure if the crossover in the middle of the telephone band is the problem or the fact that you are always stretching the response beyond the drivers comfort zone. Sure a tweeter can on paper go down to 1200 Hz. It might measure fine with acceptable distortion. But if you DSP both the tweeter and a 5" midrange with steep filters to play from 1200 to 3500hz the tweeter will sound utterly pathetic in comparison even though it measures similarly. Even my Heil tweeter will not sound as full and authoritative as the midrange driver even though some reputable companies have used it as low as 600hz
The biggest disadvantage to me seems that 3, 4, 5 way speakers get progressively further away from being a point source so imaging will inevitably be less precise than a two way, coaxial or full range speaker.
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But then my tweeter needs to go down two octaves starting at 1k? No tweeter will go that low. That will only work as a 5 way which my DSP cannot handle.
The Beyma for example seems to be fine directivity wise to past 2k which makes it possible to keep it a 4 way design.
After this first order 4 way I may try a OB 3 way with a full range driver with steeper crossovers. Something like 200hz-8000hz. Would be interesting to compare these two radically different approaches.
I'd go with the 18Sound 6ND420.
I use a pair of 6ND430 in a pair of tiny PA speakers and they're great for the size of the box etc. However, I'm typically using them down to 80Hz. The 6ND420 sacrifices some Xmax and gains some mid-band sensitivity, which I think would be useful for this project. There's also the 6ND410 as a dedicated midrange, but that will probably be lacking in lower-mid output for your application.
Chris
I use a pair of 6ND430 in a pair of tiny PA speakers and they're great for the size of the box etc. However, I'm typically using them down to 80Hz. The 6ND420 sacrifices some Xmax and gains some mid-band sensitivity, which I think would be useful for this project. There's also the 6ND410 as a dedicated midrange, but that will probably be lacking in lower-mid output for your application.
Chris
No…….if you start your slope at 8k with a 1st order filter, you’ll be down 12db at 2k…….