I'm designing an 2 way speaker with a compression driver and a midwoofer for someone and i have an issue with the big sensivity difference. Most people will arrange this with an dsp and seperate amps but for the client that is not an option at all (it needs to be foolproof for a noob and easy to set up). He will use it for various small events, mostly as background music or for presentations in a non-profit organisation but the space he uses is big.
How do you do the Lpad to take 10dB difference. The woofer is a 300W woofer and the compression driver a 60w and it will be used to it's limit sometimes. CR is a 4th order passive at 1600hz. normal resistor L-pads (with 10w or 20w resistors) won't take that load i think. Can you use a pot meter for that (internal in the cabinet set at the right point). Or do you use high power resistors like those in a metal housing like this one? https://www.mouser.be/ProductDetail...GAEpiMZZMtlubZbdhIBIOzZS54oCXX/hbM1Vkal%2BcQ= (just an example of format, not that value).
And yes, i know it's not optimal and it will create a lot of heat. But the client insist on a passive crossover and want to take the disadvantages of it. Normally i would use a dsp for this (altoug i also like passive crossovers, but even after long insisting on using a dsp he refuses.
How do you do the Lpad to take 10dB difference. The woofer is a 300W woofer and the compression driver a 60w and it will be used to it's limit sometimes. CR is a 4th order passive at 1600hz. normal resistor L-pads (with 10w or 20w resistors) won't take that load i think. Can you use a pot meter for that (internal in the cabinet set at the right point). Or do you use high power resistors like those in a metal housing like this one? https://www.mouser.be/ProductDetail...GAEpiMZZMtlubZbdhIBIOzZS54oCXX/hbM1Vkal%2BcQ= (just an example of format, not that value).
And yes, i know it's not optimal and it will create a lot of heat. But the client insist on a passive crossover and want to take the disadvantages of it. Normally i would use a dsp for this (altoug i also like passive crossovers, but even after long insisting on using a dsp he refuses.
Some thoughts:
- An off-the-shelf active speaker from Yamaha/EV/JBL is likely to be a better solution here. Those things have built-in processing to make sure they sound decent, and lots of different limiters (excursion, peak, RMS power) to make sure they don't break when they're pushed hard.
- Depending on the compression driver, 1.6kHz might be asking too much. I've run a 1" compression driver that low for PA use when there was a single 6" midbass covering 100Hz-1.6kHz. ie, the SPLs were pretty low.
Knowing the makes & models of the drivers would be useful.
- Yes, you can use an L-pad to reduce the level of the compression driver. That may or may not be the best solution, though: since constant-directivity horns show a declining response towards the treble, you might find it's best to equalise that response within the crossover, and then see how much attenuation is really needed. It might be less than you think.
In fact, the last PA speaker crossover I designed had zero resistors.
- Decent 20w resistors will likely be fine here, but you can simulate what you're trying to do. I use XSim.
- Depending on how large the space is, what sort of events they'll be, etc, subwoofers may be required.
Chris
- An off-the-shelf active speaker from Yamaha/EV/JBL is likely to be a better solution here. Those things have built-in processing to make sure they sound decent, and lots of different limiters (excursion, peak, RMS power) to make sure they don't break when they're pushed hard.
- Depending on the compression driver, 1.6kHz might be asking too much. I've run a 1" compression driver that low for PA use when there was a single 6" midbass covering 100Hz-1.6kHz. ie, the SPLs were pretty low.
Knowing the makes & models of the drivers would be useful.
- Yes, you can use an L-pad to reduce the level of the compression driver. That may or may not be the best solution, though: since constant-directivity horns show a declining response towards the treble, you might find it's best to equalise that response within the crossover, and then see how much attenuation is really needed. It might be less than you think.
In fact, the last PA speaker crossover I designed had zero resistors.
- Decent 20w resistors will likely be fine here, but you can simulate what you're trying to do. I use XSim.
- Depending on how large the space is, what sort of events they'll be, etc, subwoofers may be required.
Chris
Two way is inherently a bad idea when it comes to horns.
Alternative one: Woofer is used to high (my 15" are crossed over at 300Hz), but the horn will be small enough to manage to produce treble in a good way.
Alternative two: The horn is too big, and can only do midrange, requiring a tweeter/supertweeter, but that was not the plan, so let's not talk about it.
Also, PA woofers don't produce bass the way hifi speaker do, so you might need a subwoofer. Maybe if you make the box large enough, I don't know.
Alternative one: Woofer is used to high (my 15" are crossed over at 300Hz), but the horn will be small enough to manage to produce treble in a good way.
Alternative two: The horn is too big, and can only do midrange, requiring a tweeter/supertweeter, but that was not the plan, so let's not talk about it.
Also, PA woofers don't produce bass the way hifi speaker do, so you might need a subwoofer. Maybe if you make the box large enough, I don't know.
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Wel, the driver will be Faital 12PR320 and a B&C DE250 compression driver in a B&C ME45 horn (altough that horn can still change, i'm still in studying phase). This should work, i see that compression driver used in high power system way lower (like at 1200Hz) while i would do it at 1600Hz which most describe as absolutly safe on distortion on higher volumes. I did do sims in XSIM also, but i got that the LPad resistor in series will take 80w on maximum volume...
I did make a crossover (prestudy) design that is using 4 parallel resistors for that position and then it goes below 50w a resistor. I know that is not realistic (as the tweeter will never get 300w in that config), so 4 resistors of 20w could do the job, but it's a bit clumsy i think.
Btw, i have no drivers or so yet, so i'm working with the published graphs, I will off course measure them when i have them in the cabinet before i make the final version of the crossover. It's just checking options and so i'm doing now. I need to come with a plan to the client before i can start building.
And on prebuild off the shelf speakers, not an option for him. It's an artistic project, and they want an unique cabinet in (ply)wood that they can paint artisticly so it fit the atelier where they are working. A plastic bland mainstream box would be cheaper and easier altough, i and he knows that.
I did make a crossover (prestudy) design that is using 4 parallel resistors for that position and then it goes below 50w a resistor. I know that is not realistic (as the tweeter will never get 300w in that config), so 4 resistors of 20w could do the job, but it's a bit clumsy i think.
Btw, i have no drivers or so yet, so i'm working with the published graphs, I will off course measure them when i have them in the cabinet before i make the final version of the crossover. It's just checking options and so i'm doing now. I need to come with a plan to the client before i can start building.
And on prebuild off the shelf speakers, not an option for him. It's an artistic project, and they want an unique cabinet in (ply)wood that they can paint artisticly so it fit the atelier where they are working. A plastic bland mainstream box would be cheaper and easier altough, i and he knows that.
Could you provide a link to the product where a DE250 is being used down to 1200Hz in a high-power situation?
The resistors will see that power when there's a full-scale sine wave at that frequency. Unlikely to happen in reality - most musical energy is in the lower-midrange and bass.
Chris
The resistors will see that power when there's a full-scale sine wave at that frequency. Unlikely to happen in reality - most musical energy is in the lower-midrange and bass.
Chris
I think it’s a good driver combo. A stock 12dB/oct at 2kHz would work well here. Make sure you include a bulb/fuse to protect the HF. Some stock crossovers have this inbuilt. Here is one that would work well for you, includes protection. Add a variable LPAD.
https://www.eminence.com/speakers/crossover-detail/?model=PXB21k6
https://www.eminence.com/speakers/crossover-detail/?model=PXLPAD
For the application specified I wouldn’t spend time on tailor made crossover. Stock crossovers work well to protect the drivers and sound just fine. Not perfect of of course.
https://www.eminence.com/speakers/crossover-detail/?model=PXB21k6
https://www.eminence.com/speakers/crossover-detail/?model=PXLPAD
For the application specified I wouldn’t spend time on tailor made crossover. Stock crossovers work well to protect the drivers and sound just fine. Not perfect of of course.
