Hi there. I'm running a bi-amped open baffle system with fostex FE207s and
two 15 inch Eminence Alphas per channel. Dbx active XO. It sounds pretty darn good, but there is always a certain slowness/ woolyness to the bass which I can't EQ out. How can I tighten things up? I am using an old intergrated amp for bass that puts out around 60 watts a channel. Do I need a much more powerfull amp? It's a 4 Ohm load so maybe the amp is struggling? I've been looking at PA amps as they seem to offer much more wattage for not alot of dollars, but I'm not sure if it would be money well spent.
Thank you.
two 15 inch Eminence Alphas per channel. Dbx active XO. It sounds pretty darn good, but there is always a certain slowness/ woolyness to the bass which I can't EQ out. How can I tighten things up? I am using an old intergrated amp for bass that puts out around 60 watts a channel. Do I need a much more powerfull amp? It's a 4 Ohm load so maybe the amp is struggling? I've been looking at PA amps as they seem to offer much more wattage for not alot of dollars, but I'm not sure if it would be money well spent.
Thank you.
Long shot here ... maybe your crossover point is set a bit too high
Those big 15's would rather go down in octaves than come up into the mid range ... if being crossed and used as base drivers
DISCLOUSER ... I am not familiar with your speakers or OB theory and operation but ...
Try crossing the 15's one octive above the 15's minus 3db point
Again not being familar with your set up ... but if those 15's are say -3db at 25 HZs ... then try setting the crossover at 50 HZs
Had you said "Fat" "Boomy" or "Bloated" ... I would agree that parametric EQing could reduce peaks and modal ringing ... but "SLOW" makes me think crossover point is a bit high
Won't cost nothing to roll the X/O freq. down a little ... give it a try and let us know
Those big 15's would rather go down in octaves than come up into the mid range ... if being crossed and used as base drivers
DISCLOUSER ... I am not familiar with your speakers or OB theory and operation but ...
Try crossing the 15's one octive above the 15's minus 3db point
Again not being familar with your set up ... but if those 15's are say -3db at 25 HZs ... then try setting the crossover at 50 HZs
Had you said "Fat" "Boomy" or "Bloated" ... I would agree that parametric EQing could reduce peaks and modal ringing ... but "SLOW" makes me think crossover point is a bit high
Won't cost nothing to roll the X/O freq. down a little ... give it a try and let us know
Hey Dhrab. I must have crossed those thing at every frequency known to man! Still can't get the clarity I'm looking for...I settled on 250hz with steepest roll off I've got (24db.) same cut off on the fostex. As for the minus 3db point, if the lowest they can produce is 46hz, then for an octave would XO point be around 90hz? I'll look into running them in series for a test.
Thanks guys for all your replies.
Thanks guys for all your replies.
That "Slowness" is probably due to the High Q in the 15" Alphas. There's nothing that can be done. It's the characteristic of the driver itself.
Here are some articles relating to loudspeaker Q.
This may be old news to you, but others may not know: when running the 15" drivers OB, the acoustic XO point may not be the same as the electronic XO point. I built a slightly modified version of MJK's small passive OB w/ FF85K and Alpha 15a; I have the electronic XO points at 165 Hz and 500 Hz, both second order. To those who have been building nothing but standard box enclosures that will seem mighty strange! You have to examine how your OB design interacts with the behavior of the drivers.
For more info, check out MJK's web site: Quarter Wavelength Loudspeaker Design
Cheers, Jim
For more info, check out MJK's web site: Quarter Wavelength Loudspeaker Design
Cheers, Jim
Although MJK denies any problem with a high q woofer, your experience
does not bear this out. Some people like a rolling bass , others something
a bit tighter.
I do not think two woofers will have the same clarity as one, although having
two will definitely help with having an integrated sound. with one woofer the distance between the two drivers makes for a non integrated sound, with one
note from a bari sax, for instance, coming from the bass driver, and the next note eminating from the fullranger. this is less of a problem the further one is from the speaker. and of course there is no free lunch and I am not saying that a speaker with two such drivers is a bad speaker. Not at all.
try recapping the PS in your amp. Or try something with a higher damping factor, maybe class d for the bass. I don't think more power is the answer.
good luck. try at least 4' from the wall instead of 3', if you have not already.
does not bear this out. Some people like a rolling bass , others something
a bit tighter.
I do not think two woofers will have the same clarity as one, although having
two will definitely help with having an integrated sound. with one woofer the distance between the two drivers makes for a non integrated sound, with one
note from a bari sax, for instance, coming from the bass driver, and the next note eminating from the fullranger. this is less of a problem the further one is from the speaker. and of course there is no free lunch and I am not saying that a speaker with two such drivers is a bad speaker. Not at all.
try recapping the PS in your amp. Or try something with a higher damping factor, maybe class d for the bass. I don't think more power is the answer.
good luck. try at least 4' from the wall instead of 3', if you have not already.
Hi,
Its probably nothing to do with driver Q and all to do with too much driver
overlap caused by using symmetrical electrical filters when the real issue
is the acoustic responses of the drivers on the baffle.
Typically something lik 2nd order electrical L/R low pass on the bass
units at 200Hz, and 400Hz to 500Hz 2nd order electrical L/R high pass
on the mid/treble unit is need to avoid an upper bass / low mid hump.
Thsse numbers are for an around 2ft wide open baffle, c/o ~ 300Hz.
rgds, sreten.
Its probably nothing to do with driver Q and all to do with too much driver
overlap caused by using symmetrical electrical filters when the real issue
is the acoustic responses of the drivers on the baffle.
Typically something lik 2nd order electrical L/R low pass on the bass
units at 200Hz, and 400Hz to 500Hz 2nd order electrical L/R high pass
on the mid/treble unit is need to avoid an upper bass / low mid hump.
Thsse numbers are for an around 2ft wide open baffle, c/o ~ 300Hz.
rgds, sreten.
Sorry for hijacking your thread!
Guy's I am/was about to order 4 alpha 15's for an OB with a small wide band driver taking care of everything above 200hz. The tautness or punch of these drivers is also a concern of mine as I listen to everything from jazz to drum and bass dance music. I will use an active xo and be powering the bottom end separately with an old marantz 300Dc it is a beast of an amp but only has a damping factor of 60, 8ohm,20hz. Am I barking up the wrong tree?
Guy's I am/was about to order 4 alpha 15's for an OB with a small wide band driver taking care of everything above 200hz. The tautness or punch of these drivers is also a concern of mine as I listen to everything from jazz to drum and bass dance music. I will use an active xo and be powering the bottom end separately with an old marantz 300Dc it is a beast of an amp but only has a damping factor of 60, 8ohm,20hz. Am I barking up the wrong tree?
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Crikey! thats a lot to chew over. I'll get back here when I've tried a few things out.
In the mean time I was thinking of one of these: http://http://www.parts-express.com/pe/showdetl.cfm?Partnumber=245-502
damping factor of 200. Massive power. fan might be noisy. Anyone use a PA amp for bass duties?
In the mean time I was thinking of one of these: http://http://www.parts-express.com/pe/showdetl.cfm?Partnumber=245-502
damping factor of 200. Massive power. fan might be noisy. Anyone use a PA amp for bass duties?
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