Ok i'm getting a e12A.44 elemental designs A series speaker. i'm going to eventualy power it with a 1200watt mono block amp. but for now i'm going to power it with my 600watt rms A/B amplifier. well the problem is till i get my 1200watt amp this sub well be in a ported box tuned to 27hz well the only inline crossovers i can find come in either 20hz high pass and 30hz high pass.... seems to me you want to be at or below your tuned frequency so 30hz is out and 20hz seems like it may be too low is it? if it is i can get one custom built for reasonable just well take me quite awhile.
Replies (8)
asplundher on 02/28/2004 11:02:55
The 30hz should be close enough being that there is only a 3hz difference. How steep is the slope of the filter? If is not that steep then I definitely don't see a problem; especially when there is not that much music material below that area. The 20hz shouldn't be that bad either (7hz). Making one with a steep enough slope would be quite expensive and also a bit of a task.
swez on 02/28/2004 11:13:45
Agreed..
A 30 Hz. SS filter is appropriate as most music we listen to, does not drop much below 35 Hz. Any noise in the audio chain below the tune freq is what you need to block out.
Since you have choosen 27 Hz. as your port tune point, the 30 Hz filter is the right choice. A 20 Hz filter may allow freqs below 27 Hz to pass into the subs and be harmful to subs at high SPL levels.
FMODS are 12dB sloped, so at 15 Hz, (1 octave below 30 Hz) you have a -12dB cut in power to the sub. That's plenty good. If you choose a 20 Hz filter, there is full amplification of frequencies down to 20 Hz. At 10 Hz, you have a -12 dB down point.
In short... use the 30 Hz filter.
Swez
uochronos on 02/28/2004 13:39:08
ok 30hz it is i just didnt want to lose anything important sound wise thanks.... and i'll be going with a 18 or 24db slope... weather i buy it or build it... trying to keep all my xovers at that range. even if i build it should not cost me too much my neighbor has been building home/car stereo componenets since the 70's and well help me put one together for a good price.
asplundher on 02/28/2004 16:02:29
A steeper slope should make that a perfect match with that amount of power. I think you will be very pleased with the results. One question though; I assume the one you will be building (if you choose to) will be passive? If so, it could rob you of some amp power. How much I don't exactly know but, with that kind of wattage I doubt you will be able to tell. Nothing major to worry about though. A passive ss filter in your case will definitely help more than hurt.
uochronos on 02/28/2004 16:31:09
this xover is a temp fix like i said for my 600watt amp thats current once i get the 1200watt amp it has a SS filter on board so i wont have to worrk about losing amp power once i get my end amp. thanks for the tip though
swez on 02/28/2004 19:18:28
Passive filters do have an "insertion loss" associated with them. Since you are thinking 18/24 db slope, that's a 3rd or 4th order Butterworth or similar. That means several large caps and coils. These caps can get expensive and bulky too and coils are heavy as well.
I looked at that option for my shop sub system (15") and depending on power handling needs (1200 RMS) I found it much cheaper to get a preamp input filter than make one.
The FMODS are $30.00 a pair... get them in 3 days and be done with it... unless you are determined to go the long way home.
Swez
uochronos on 02/29/2004 03:15:49
now now that i know i can use a 30hz FMOD i well get one of them the building custom one was pretty much if i wanted to get exactly 27hz cut off. which looking into it today would be expensive and complicated.
swez on 02/29/2004 08:09:04
At least you did some homework on the matter and now you know the down side of a passive filter network.
Besides, there is very little music content below 35 Hz. That is, unless you like Church organ music or orchestral classics.
Swez
Replies (8)
asplundher on 02/28/2004 11:02:55
The 30hz should be close enough being that there is only a 3hz difference. How steep is the slope of the filter? If is not that steep then I definitely don't see a problem; especially when there is not that much music material below that area. The 20hz shouldn't be that bad either (7hz). Making one with a steep enough slope would be quite expensive and also a bit of a task.
swez on 02/28/2004 11:13:45
Agreed..
A 30 Hz. SS filter is appropriate as most music we listen to, does not drop much below 35 Hz. Any noise in the audio chain below the tune freq is what you need to block out.
Since you have choosen 27 Hz. as your port tune point, the 30 Hz filter is the right choice. A 20 Hz filter may allow freqs below 27 Hz to pass into the subs and be harmful to subs at high SPL levels.
FMODS are 12dB sloped, so at 15 Hz, (1 octave below 30 Hz) you have a -12dB cut in power to the sub. That's plenty good. If you choose a 20 Hz filter, there is full amplification of frequencies down to 20 Hz. At 10 Hz, you have a -12 dB down point.
In short... use the 30 Hz filter.
Swez
uochronos on 02/28/2004 13:39:08
ok 30hz it is i just didnt want to lose anything important sound wise thanks.... and i'll be going with a 18 or 24db slope... weather i buy it or build it... trying to keep all my xovers at that range. even if i build it should not cost me too much my neighbor has been building home/car stereo componenets since the 70's and well help me put one together for a good price.
asplundher on 02/28/2004 16:02:29
A steeper slope should make that a perfect match with that amount of power. I think you will be very pleased with the results. One question though; I assume the one you will be building (if you choose to) will be passive? If so, it could rob you of some amp power. How much I don't exactly know but, with that kind of wattage I doubt you will be able to tell. Nothing major to worry about though. A passive ss filter in your case will definitely help more than hurt.
uochronos on 02/28/2004 16:31:09
this xover is a temp fix like i said for my 600watt amp thats current once i get the 1200watt amp it has a SS filter on board so i wont have to worrk about losing amp power once i get my end amp. thanks for the tip though
swez on 02/28/2004 19:18:28
Passive filters do have an "insertion loss" associated with them. Since you are thinking 18/24 db slope, that's a 3rd or 4th order Butterworth or similar. That means several large caps and coils. These caps can get expensive and bulky too and coils are heavy as well.
I looked at that option for my shop sub system (15") and depending on power handling needs (1200 RMS) I found it much cheaper to get a preamp input filter than make one.
The FMODS are $30.00 a pair... get them in 3 days and be done with it... unless you are determined to go the long way home.
Swez
uochronos on 02/29/2004 03:15:49
now now that i know i can use a 30hz FMOD i well get one of them the building custom one was pretty much if i wanted to get exactly 27hz cut off. which looking into it today would be expensive and complicated.
swez on 02/29/2004 08:09:04
At least you did some homework on the matter and now you know the down side of a passive filter network.
Besides, there is very little music content below 35 Hz. That is, unless you like Church organ music or orchestral classics.
Swez
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