hi
i have built bk12m speakers using fostex fe126en drivers. the Fs of these drivers is 83hz. since i dont have proper measuring setup, can anybody who have tried it (or measured it), tell me upto what freq. these speakers go down? i am interested in augmenting the lows with a dedicated woofer/subwoofer. also i need help in selecting a low cost woofer/sub for these drivers.
i have built bk12m speakers using fostex fe126en drivers. the Fs of these drivers is 83hz. since i dont have proper measuring setup, can anybody who have tried it (or measured it), tell me upto what freq. these speakers go down? i am interested in augmenting the lows with a dedicated woofer/subwoofer. also i need help in selecting a low cost woofer/sub for these drivers.
subs aplenty
The best moderately priced sub would be the REL 5 at about $600.if your
funds are limited ( who in diy audio aren't?) a great place to look at powered subs is a company called deep discount on ebay.I am currently
using their 8" 300watt sub.My room is small.they have 10",12",and 15"
models, all under $300.
The best moderately priced sub would be the REL 5 at about $600.if your
funds are limited ( who in diy audio aren't?) a great place to look at powered subs is a company called deep discount on ebay.I am currently
using their 8" 300watt sub.My room is small.they have 10",12",and 15"
models, all under $300.
Which totally negates the point of having the BK-12m Chris. If the gentleman wishes to follow your advice (which is reasonable in the abstract -I also like a ~500Hz XO frequency to dedicated bass units per channel if outright dynamic range is the priority) then he might as well junk the enclosures and stuff his 126s into sealed boxes. Which would be a bit of a waste of his time, effort and money thus far. The BK-12m is a decent little performer for what it is (I know, because I designed it), and should give solid performance for most reqirements if crossed to a quality sub. around 70Hz or so.
If you can run two subs., so much the better of course.
You don't necessarily need / want to place them per channel though as you would with woofers covering a wider BW -I would follow Harman's approach on this score.
The Fs of the driver is largely immaterial as far as the lower cutoff frequency (F0) of a horn is concerned, since this is essentially a function of the flarepath length & profile. F0 on the BK-12m is 70Hz.
If you can run two subs., so much the better of course.
You don't necessarily need / want to place them per channel though as you would with woofers covering a wider BW -I would follow Harman's approach on this score. The Fs of the driver is largely immaterial as far as the lower cutoff frequency (F0) of a horn is concerned, since this is essentially a function of the flarepath length & profile. F0 on the BK-12m is 70Hz.
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With lower frequency crossovers, you're much better off going for line-level crossovers rather than speaker-level.
The impedance peaks caused by the cabinet loading will interact with the crossover, creating a peaky response around the impedance peaks.
The required parts will also be very large in value, and will therefore be rather expensive.
Line level crossovers are great if you have another amplifier lying around (or if the sub has one built in), as they use much smaller-value components (= far cheaper), without having to worry about the speaker impedance throughout the XO region. There's some good articles on active crossovers (and other stuff) here
(Again, IMHO) Steeper crossovers can be beneficial in bringing out the dynamics in a speaker, as the greater rate of attenuation means less low bass reaching the FR driver (so there's less stress on the driver). However, higher order crossovers have greater phase shifts and component counts than the lower order ones, so a compromise is to be found.
Page 3 of this PDF is useful - the bass is flat to ~75Hz, -6dB @ ~65Hz.
Chris
The impedance peaks caused by the cabinet loading will interact with the crossover, creating a peaky response around the impedance peaks.
The required parts will also be very large in value, and will therefore be rather expensive.
Line level crossovers are great if you have another amplifier lying around (or if the sub has one built in), as they use much smaller-value components (= far cheaper), without having to worry about the speaker impedance throughout the XO region. There's some good articles on active crossovers (and other stuff) here
(Again, IMHO) Steeper crossovers can be beneficial in bringing out the dynamics in a speaker, as the greater rate of attenuation means less low bass reaching the FR driver (so there's less stress on the driver). However, higher order crossovers have greater phase shifts and component counts than the lower order ones, so a compromise is to be found.
Page 3 of this PDF is useful - the bass is flat to ~75Hz, -6dB @ ~65Hz.
Chris
Which totally negates the point of having the BK-12m Chris. If the gentleman wishes to follow your advice (which is reasonable in the abstract -I also like a ~500Hz XO frequency to dedicated bass units per channel if outright dynamic range is the priority) then he might as well junk the enclosures and stuff his 126s into sealed boxes. Which would be a bit of a waste of his time, effort and money thus far. The BK-12m is a decent little performer for what it is (I know, because I designed it), and should give solid performance for most reqirements if crossed to a quality sub. around 70Hz or so.
If you can run two subs., so much the better of course.
The Fs of the driver is largely immaterial as far as the lower cutoff frequency (F0) of a horn is concerned, since this is essentially a function of the flarepath length & profile. F0 on the BK-12m is 70Hz.
thats true! no point in crossing high. i like these small wonders, just because these speakers can produce vocals so well. totally non-ear-fatiguing. can go for listening to them for hours. thats why i am careful in chosing sub/woofer for these. addition of woofer/sub should not disturb the natural sound these fostex are producing already.
one more thing i am worried is, will any sub that i will add, can match the dynamics of the fostex drivers? i mean the FE126 are quite fast. how about a single eminence beta 12 in closed/ported box?
essentially what you are suggesting is nothing but bi-amping. can give a try. now i want to know one last thing, whether to go for single sub/woofer or one per channel, considering the xover point as 70hz. if going for single, then powered sub makes sense, right?
Single is OK at that frequency, although twin usually have the edge. An active sub. with its own amp & onboard XO is the way to go, or you're going to find the parts required get very large, very expensive, and have very considerable insertion losses.
Bass by definition is slow. Providing you don't run a bass driver up higher than it is capable of going, and use steep XO slopes to ensure it is quickly attenuated you shouldn't have too many problems.
Bass by definition is slow. Providing you don't run a bass driver up higher than it is capable of going, and use steep XO slopes to ensure it is quickly attenuated you shouldn't have too many problems.
for making xover slope steep, i think i can go for LR4 active xover ckt.
how about using 6.5" driver each per channel to cover below 70hz. i have a pair lying around which can go down to 45hz. but i am not sure, if 6.5" drivers can move as much air as that of 8" driver, to get that 'bass' feeling.
not all 6s are created equal, and some are certainly capable of providing "that feeling" for most domestic environs, particularly if double teaming
I'd consider XO as high as 90-120 range - as chris661 notes, passive at these frequencies is doable, with some technical issues, but the component cost alone makes passive line level very attractive. If implementing plate sub-amp(s), and with a line level pre-amp, the HP for the mains could be as simple as a single inline cap - or of course as elaborate as you need it to be.
I use the 6.5" TB subs (got them just before Neodymium went expensive - fortunately, there's a ferrite version that's a drop-in replacement) and think they're great.
In a 5m by 4m room, they'll make themselves felt as well as heard.
4th order active crossover will be fine. As for the 6.5" drivers - it rather depends. For normal listening levels, they'll probably be okay. Cranked up, they may be found lacking in headroom.
If you have enough amplifiers to try it, knocking together a couple of boxes is worthwhile - certainly far less money spent than buying a complete subwoofer.
Your location will probably dictate (to some extent) your driver choice, but playing around on a simulation program will help you choose. I can recommend WinISD Pro.
It might also be worth going for an EBS alignment - these allow the bass response to sag slightly, by using a larger, lower tuned alignment. This means that, once room and boundry gain is applied, you end up with a flatter response than a conventionally tuned cabinet. I found my TBs in a 11L 40Hz tuned cabinet to have far too much low bass (the simulation showed virtually flat to ~40Hz), so had to stuff the port. YMMV - the EBS alignment, as mentioned above, uses a larger cabinet - if space is a concern, that's worth bearing in mind.
HTH
Chris
PS - if you post up the T/S parameters for your 6.5" drivers, one of our resident Hornresp experts might suggest a more exotic cabinet for them.
link for the woofer.
Visaton - Lautsprecher und Zubehör, Loudspeakers and Accessories
in another thread, i have discussed abt its usage in TL, but that has been ruled out due to its high Qts value. its not mandatory to use only these drivers anyway. i am ready to go for other 8" or 10" drivers if better suite is found for bk12m speakers.
If you went for a conventional sealed enclosure, they'd always have a bump before rolloff (the speaker's Qts > 0.7).
You could use something like a Linkwitz Transform (or a simple parametric eq) to get rid of the peak. With the LT, you could also choose the low frequency rolloff of the subwoofers.
I wouldn't recommend trying to go low with those drivers, though - they are definitely midbasses, so I wouldn't expect them to cover subwoofer duties so well.
Do you have any other drivers in mind?
You could use something like a Linkwitz Transform (or a simple parametric eq) to get rid of the peak. With the LT, you could also choose the low frequency rolloff of the subwoofers.
I wouldn't recommend trying to go low with those drivers, though - they are definitely midbasses, so I wouldn't expect them to cover subwoofer duties so well.
Do you have any other drivers in mind?
eminence beta and alpha 12a's are available locally. i am considering them because several people have used them with fostes drivers in OBs. Beta can go down to 40hz in a ported box i think. else Ahuja PA drivers are also alternate options ( Ahuja Sound Solutions ) for me. importing such heavy sub/woofers will be very costly.
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