Hello,
Anyone have access to the proper passive crossovers or schematics for the BM12CXA + BM-D440 compression drivers?
This is a coax 12"
thanks!
Anyone have access to the proper passive crossovers or schematics for the BM12CXA + BM-D440 compression drivers?
This is a coax 12"
thanks!
I don't have them on-hand, but it's easy enough to design a passive crossover if you've got some measurement gear.
Chris
Chris
Going passive you'll need first to move crossover point higher due to relatively low order and second put resistance for compensation of higher HF sensitivity.
First will result in bad directivity match. You'll have narrow needle at 1,5-2 kHz from 12" while 1" exit driver will be wide like 60 degree. This will provide you with a bad beaming across a whole 1-3kHz band where maximum of human hearing are.
Resistance at HF driver will highly reduce damping factor which is critical to high-quality factor HF driver.
So, there are a way better to use active filters.
Do you have some kind of measurement setup - mic and audiocard?
Very good observation. Too bad it is not taken too seriously.
In my home setup i am using
4.2mH 20u for the woofer.
3.9u 0.7m 20u (16-20u will give same results) 2.5R series 7.3R parallel (these two won't affect damping much)
Driver wired in phase.
Schematic is with diff values.
The problem with this unit is that the driver sounds a bit dirty on the low-HF and the woofer is neither exemplary on the mid.
Due to the construction of the coaxial driver you have a 1.1kHz dip in the response then a peak at 2k with high beaming
So either go with the beaming and keep the driver in the good sounding region, or go below and cross at 1.3k (acoustically) and live with a bit of driver harshness.
You could use google translate:
Bass reflex cu PAudio bm12cxa - Page 2 - Loudspeakers and boxes - ELFORUM - Forumul electronistilor
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From P.Audio
This is their recommended crossover:
View attachment BM-12CXA-1.pdf
schematic
Also:
C4 is bi-cap optional . so, you can used it if you need super hi frequency 18-22kHz.
And you can add band pass filter (see file attached ) drop 4.5 kHz peak .The attached file used R+C+L connect HF output to ground. Below for recommend.
R ceramic 25-50 W
C non—polar 250v
L iron core . #20
This is their recommended crossover:
View attachment BM-12CXA-1.pdf
schematic
Also:
C4 is bi-cap optional . so, you can used it if you need super hi frequency 18-22kHz.
And you can add band pass filter (see file attached ) drop 4.5 kHz peak .The attached file used R+C+L connect HF output to ground. Below for recommend.
R ceramic 25-50 W
C non—polar 250v
L iron core . #20
This is probably for PA use as a top or a monitor with not much output below 100Hz.
Mine is for home setup, as you can see it sacrifices the midrange for even out the response to be in line with the low end.
I would not use any iron ore coils as the values are too low to be worth it. As for the bandpass filter you can use thin wire and account for the Rdc, as in substract the Rdc from the value of the resistor.
Mine is for home setup, as you can see it sacrifices the midrange for even out the response to be in line with the low end.
I would not use any iron ore coils as the values are too low to be worth it. As for the bandpass filter you can use thin wire and account for the Rdc, as in substract the Rdc from the value of the resistor.
You should not compare a bass reflex with a horn.
Way different baffle step compensation required and also different low end and MB response.
My values are for a home setup that cuts the SPL so it would sound with more bass.
Also keep in mind that 3mH with or without a zobel is a bit different than a 3mH or 4mH with a 20-30u cap.
The cap would bump up the part towards the crossover point and of course steepen up the slope.
Maybe you can simm with the cap as well, but i doubt it would fit your needs.
Way different baffle step compensation required and also different low end and MB response.
My values are for a home setup that cuts the SPL so it would sound with more bass.
Also keep in mind that 3mH with or without a zobel is a bit different than a 3mH or 4mH with a 20-30u cap.
The cap would bump up the part towards the crossover point and of course steepen up the slope.
Maybe you can simm with the cap as well, but i doubt it would fit your needs.
Thank you all for sharing crossover setup! I am planning to try Sharky setup. By any chance can you ad your crossover photo, to see how you finished? 🙂 I have built 108.3l enclosers with vent 10 years ago 😀 and have not finished with crossovers 🙂 I am planning to play with Quad II tube amp 🙂
I used an iron core for the 4mH coil with different outputs from 3 to 12mH.
Otherwise just wires and point to point wiring on a board. It's on the outside as makes the tunning a less of a hustle. The boxa has 2 pair of binding posts for each driver.
The bulb is 24V 21W, in series with the driver, after la Lpad. It barely glows with normal music.
It handles safely 500W amplifier with a clip limiter.
The looks are not too good as i don't like the sound very much, never bothered to make it better looking.
I have a pair of scanspeak 18w8545k and 9600 or something like that and they sound a lot better.
So those speakers were put aside. The sound is not great, but not terrible. Mediocre quality for my taste.
The crossover is also easily tunnable and used for other experiments as well.
One more thing about this driver, the cone does not have any centering flange, so be careful if you open it as it might be offset a bit and it will create peaks and dips into the response. I would recommend measuring it and re-center it again and again until the response is flat in the 800-3k range with no big and wide dips.
Otherwise just wires and point to point wiring on a board. It's on the outside as makes the tunning a less of a hustle. The boxa has 2 pair of binding posts for each driver.
The bulb is 24V 21W, in series with the driver, after la Lpad. It barely glows with normal music.
It handles safely 500W amplifier with a clip limiter.
The looks are not too good as i don't like the sound very much, never bothered to make it better looking.
I have a pair of scanspeak 18w8545k and 9600 or something like that and they sound a lot better.
So those speakers were put aside. The sound is not great, but not terrible. Mediocre quality for my taste.
The crossover is also easily tunnable and used for other experiments as well.
One more thing about this driver, the cone does not have any centering flange, so be careful if you open it as it might be offset a bit and it will create peaks and dips into the response. I would recommend measuring it and re-center it again and again until the response is flat in the 800-3k range with no big and wide dips.
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