I have recently finished a pair of 2 way MEHs (described here https://www.diyaudio.com/community/threads/2-way-synergy-inspired-by-spl-runt.378456/ ) and I also plan to use a 1" driver for my next build, which will be most probably 3 way, but might actually end up as 2 way only. I will need a new pair of drivers, so I would like to summarize the options first.
The most important criteria are good response down to allow crossover between 800 - 1000 Hz, short distance from the phase plug to exit (flat construction) to move the cancellation notch as high as possible in frequency for the section below it.
I started using Extron XPA1002 amplifiers that have input signal detection at -40 dBu +- 3 dB and nominal input level at 4dBU. When the input signal detection goes on for the HF section, it is already getting uncomfortably loud. At that point, an 8ohm driver receives less than 0.6 W average if my calculations are correct (41 dB less than 60 W).
If I am correct, excursion limited power handling decreases by factor of 4 for each octave. Therefore a driver able to handle 30 W with 1200 Hz crossover point should be able to handle 15 W at 850 Hz. Edit: This is most probably not correct.
If my assumptions above are correct (please let me know if wrong), then there are actually quite a lot of suitable drivers out there. These are the ones I have tested or I remember them being suggested somewhere else.
D.A.S. Audio M50 - this is the one currently installed. It has good response down to 600 Hz, has a relatively flat construction, but not a flat frequency response above intended crossover point , it needs a quite a bit of EQ and it rolls off past 16 kHz. For DSP based crossover, it works fine, passive crossover would be difficult. It also needed a little modification for standard 1" exit mounting (originally a screw on).
BC DE500 - this one needed a little boost on the low end at the crossover region to match the target curve better, but worked fine. My pair had a rolling of FR above 5 kHz in any horn I tried, bought the second hand, they might have had an issue, since datasheet FR looked pretty differently. Out of production.
BMS4550 - the obvious choice, capable of 800 Hz crossover point.
FaitalPro HF109 - this one looks as a very good candidate as well. Specified minimum crossover is 1300 Hz at 60 W which translates to 15 W at 650 Hz and the low end roll off starts also about there. Its datasheet FR seems to be flatter than that one of the BMS4550.
BMS4552 - recommended by cowanaudio, a nice and compact driver with 1 kHz recommended crossover with manufacturer declared FR down to 500 Hz.
Any addition to the list and discussion about suitability of the candidates for the purpose is really welcome.
The most important criteria are good response down to allow crossover between 800 - 1000 Hz, short distance from the phase plug to exit (flat construction) to move the cancellation notch as high as possible in frequency for the section below it.
I started using Extron XPA1002 amplifiers that have input signal detection at -40 dBu +- 3 dB and nominal input level at 4dBU. When the input signal detection goes on for the HF section, it is already getting uncomfortably loud. At that point, an 8ohm driver receives less than 0.6 W average if my calculations are correct (41 dB less than 60 W).
If I am correct, excursion limited power handling decreases by factor of 4 for each octave. Therefore a driver able to handle 30 W with 1200 Hz crossover point should be able to handle 15 W at 850 Hz. Edit: This is most probably not correct.
If my assumptions above are correct (please let me know if wrong), then there are actually quite a lot of suitable drivers out there. These are the ones I have tested or I remember them being suggested somewhere else.
D.A.S. Audio M50 - this is the one currently installed. It has good response down to 600 Hz, has a relatively flat construction, but not a flat frequency response above intended crossover point , it needs a quite a bit of EQ and it rolls off past 16 kHz. For DSP based crossover, it works fine, passive crossover would be difficult. It also needed a little modification for standard 1" exit mounting (originally a screw on).
BC DE500 - this one needed a little boost on the low end at the crossover region to match the target curve better, but worked fine. My pair had a rolling of FR above 5 kHz in any horn I tried, bought the second hand, they might have had an issue, since datasheet FR looked pretty differently. Out of production.
BMS4550 - the obvious choice, capable of 800 Hz crossover point.
FaitalPro HF109 - this one looks as a very good candidate as well. Specified minimum crossover is 1300 Hz at 60 W which translates to 15 W at 650 Hz and the low end roll off starts also about there. Its datasheet FR seems to be flatter than that one of the BMS4550.
BMS4552 - recommended by cowanaudio, a nice and compact driver with 1 kHz recommended crossover with manufacturer declared FR down to 500 Hz.
Any addition to the list and discussion about suitability of the candidates for the purpose is really welcome.
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Hello,
I use this one https://sica.it/prodotto/cd-78-26-245/
With 4 pieces of FRS5x for mids (300hz-1800hz)
Crossed at 1800hz between FRSx and Sica.
EQ is needed.. I use EQApo, with passive crossovers I don't think you can manage to have the FRSx play nicely.
In a B52 horn that I added some 3d printed adaptors.
Thank you for all content/tests added to this forum!
I use this one https://sica.it/prodotto/cd-78-26-245/
With 4 pieces of FRS5x for mids (300hz-1800hz)
Crossed at 1800hz between FRSx and Sica.
EQ is needed.. I use EQApo, with passive crossovers I don't think you can manage to have the FRSx play nicely.
In a B52 horn that I added some 3d printed adaptors.
Thank you for all content/tests added to this forum!
Attachments
The Sica drivers are nice, I have a pair of another type. Unfortunately, this will not fit with the low crossover point requirement. With small mids, they work perfectly.
This page seem to indicate that you get 12dB (2 times = 6 dB, yet 2 times another 6 dB = 12 dB) for every octave of frequency raise keeping excursion constant. It seems logical that there would be some area i.e x*x effect on this aspect?
http://www.baudline.com/erik/bass/xmaxer.html
It would be valid if the impedance ("loading"?) is the same over the range that you are comparing - if loading falls, big negative things will probably happen...
//
I might have remembered that wrong. The 1/4 power per octave drop is mentioned here: https://www.diyaudio.com/community/...ivers-from-playing-1khz-at-low-volume.365491/
There was a good point in the linked thread. If manufacturer says that 1300 Hz with 12 dB/oct filter, it is safe to assume that at half frequency it would be safe with 12 dB less. And another good point is, that the real power handling / max SPL can be determined by rising distortion at the low end.
It seems that with constant displacement, the power needed to get the same SPL at half frequency is indeed +12 dB, I have checked this from two independent sources - all mentioning that it is valid for piston drivers in a sealed box. I am for sure missing something here.
It seems that with constant displacement, the power needed to get the same SPL at half frequency is indeed +12 dB, I have checked this from two independent sources - all mentioning that it is valid for piston drivers in a sealed box. I am for sure missing something here.
No need to use a coarse rule of thumb. You can plot the high pass filter curve for that 12 db XO at 1300 together with the higher slope high pass filter for a lower frequency XO and adjust slope and cutoff until the lower cutoff driver gets no more power than the higher cutoff. The problem, if any, is that the recommended 1300 Hz/ 12 db may have higher distortion than desired. So, as you say, the ultimate test is distortion at the low end.
One caution about the BMS4550 is that it has a longer distance back from the throat to its phase plug, which adds to the round trip path length for determining the reflection null.
One caution about the BMS4550 is that it has a longer distance back from the throat to its phase plug, which adds to the round trip path length for determining the reflection null.
Here is a plot I did back in the day, showing prospective crossover of HF-1440 on a 600 mm dia horn I had generated with ATH. The unequalized FR is that from the driver's data sheet convolved with the horn's response from ATH. I then auto-EQ flat with Vituix mirror and added textbook high pass filters
top curve is 700 Hz, LR12, middle curve is 400 Hz , LR24, lowest curve is 350 Hz, LR24. I don't recommend those XOs. I just show them by way of example. You can see on the graphs how much maxSPL you give up to get the lower XO.
I recall from using the BMS4550 that it had a 24 db acoustic high pass slope without any filters to which I added a 24 db electrical to create a 48 db slope.
top curve is 700 Hz, LR12, middle curve is 400 Hz , LR24, lowest curve is 350 Hz, LR24. I don't recommend those XOs. I just show them by way of example. You can see on the graphs how much maxSPL you give up to get the lower XO.
I recall from using the BMS4550 that it had a 24 db acoustic high pass slope without any filters to which I added a 24 db electrical to create a 48 db slope.