full range line source - help needed!

hi all,

i am considering a full range line source. i'm wanting something that can be eq'd as low as possible. (or perhaps they can go as low as 20hz w/o eq? i'm a novice at this, i dunno). ported or sealed is fine.

anyway, here are the driver specs; i would be using 15 of them.
• VCdia: 11/16"
• Le: 0.42 mH
• Impedance: 4 ohms
• Re: 3.52 ohms
• Frequency response: 45-18,000 Hz
• Fs: 45 Hz
• SPL: 91.3 dB 1W/1m
• Vas: 1.1 cu. ft.
• Qms: 4.25
• Qes: 0.36
• Qts: 0.34
• Xmax: 2 mm
• Dimensions: Overall diameter: 5-1/16"
i'd most likely wire 5 in series; three sets then paralleled for 6.6 ohms total. so, my question is what's cu-ft of the box (or sonotube) that i need to build?

tia,

doug s.
 
thanks, chris.

but either i'm not doing it right, or something's screwy about the figures i'm getting. (the only data i plugged in that i'm not sure about is 6.33 ohms for "series resistance" in the "signal" tab, after i've loaded all the driver perameters. but this is the resistance i'll get when running 3 sets of 5 series'd drivers in parallel.) anyway, for anywhere from a 4 to 12 cu-ft sealed box with 15 drivers, i'm getting -3db at 42hz and -14.5db at 20hz. is this because it's not eq'd at all? it seems that would require quite a bit of eq to get flat at 20hz, even w/15 drivers.

however, i'm assuming that's supposed to be ~91db, as the "signal" tab says it's at 1w, and that's the spec of the drivers. but i'd think 1w would generate significantly higher spl w/15 drivers? does this really mean it's at ~102db, w/a doubling of drivers equal to an additional 3db? so, 14.4db down at 20hz would be 87.5db? if i added eq, for flat to 20hz i could get max steady spl's at 20hz of just over 100db, w/peaks of just over 103db? (16w would give 99.5db and 32w would give 102.5db? drivers are rated at 20wrms; 40w peak)

(if i run the program with a single driver in a 1.1cu-ft box, 4 ohms resistance, i get -3db at 51hz and -15.2db at 20hz, again assuming ~91db, w/1w)

and, if the above is correct, in reality, i'd only want them flat to somewhere between 50-80hz, as they'd be actively crossed to subs at 24db/octave, which means i wouldn't need any eq except to extend the treble as they're rated flat to 18khz...

thanks for putting up w/a total newbie when it comes to this,

doug s.

Well, 30 of those drivers will be capable of just under [email protected]@20Hz in a sealed box, measured groundplane.
Wall/corner loading may help, but listening distance will work against that.

WinISD will help you size the cabinets.

Chris
 
Haven't had coffee yet, so too early for calculations, but a couple of observations.

Why 15 drivers? At 16, you could run 4 pairs of 4 and still retain that original 4 Ohms.
I tried 16 drivers, and it would struggle under 50 Hz.

Plenty of threads running these days for small fullrange line arrays. Lots to learn in them.
A 25-driver per side line arrays, still keeping the same resulting Ohms, will play down to 30Hz, according to Wesayso in his thread... with EQ of course.

Also, a flat FR up higher to 18kHz is not the best, as line arrays will have more interaction at HF and you will lose some of it, so a driver with a rising FR is often more recommended than a flat one.
 
hi perceval,

i will actually do 16/side, if the final layout allows me to; it depends on the total height of the array. the room it would be in is 8'-7" floor-to-ceiling. 16 ~6" drivers may or may not work, depending on the actual mounting. if i can overlap the mounting tabs, it should work with 16 drivers; if not, i don't think there's a lot of room left for the base and the top of the cabinet. but either way, the output won't change much. i agree; i'd prefer 4 ohms rather than 6.33 ohms.

re: final frequency response, i have a deqx, so i should be able to tailor it as i wish. the other thing i understand, re: flat frequency response is that, typically listeners prefer a mildly dropping f/r, from the midrange on up, as long as it's smooth, with no dips or peaks.

thanks,

doug s.
Haven't had coffee yet, so too early for calculations, but a couple of observations.

Why 15 drivers? At 16, you could run 4 pairs of 4 and still retain that original 4 Ohms.
I tried 16 drivers, and it would struggle under 50 Hz.

Plenty of threads running these days for small fullrange line arrays. Lots to learn in them.
A 25-driver per side line arrays, still keeping the same resulting Ohms, will play down to 30Hz, according to Wesayso in his thread... with EQ of course.

Also, a flat FR up higher to 18kHz is not the best, as line arrays will have more interaction at HF and you will lose some of it, so a driver with a rising FR is often more recommended than a flat one.
 

perceval

Member
2014-02-21 8:17 am
Taiwan
A couple of things I missed...

5" drivers are really not great for full range line arrays.
The c-to-c distance is too great, and you will run into serious comb filtering.

Plus, Vas at 1.1 cu.ft. (about 31 litres) means it will be a big enclosure... quite big.

I don't think this is a good driver selection for a line array.
 
well, the drivers are rated +/-3db from 45hz to 18khz. and everything i've read about comb filtering is that the reality is it's not audible if the drivers are edge to edge.

re: the enclosure size, with winsd, i'm getting almost the exact same frequency response with anywhere from 4cu ft to 12 cu ft. which is why i wondered if i'd entered all the parameters correctly.

doug s.

A couple of things I missed...

5" drivers are really not great for full range line arrays.
The c-to-c distance is too great, and you will run into serious comb filtering.

Plus, Vas at 1.1 cu.ft. (about 31 litres) means it will be a big enclosure... quite big.

I don't think this is a good driver selection for a line array.
 
ok, so i ran 16 drivers at 4 ohms instead of 15 at 6.33 ohms. interestingly enough, the results went from -3db at 42hz & -14.5db at 20hz to -3db at 50hz and -15.5db at 20hz.

doug s.
Haven't had coffee yet, so too early for calculations, but a couple of observations.

Why 15 drivers? At 16, you could run 4 pairs of 4 and still retain that original 4 Ohms.
I tried 16 drivers, and it would struggle under 50 Hz.

Plenty of threads running these days for small fullrange line arrays. Lots to learn in them.
A 25-driver per side line arrays, still keeping the same resulting Ohms, will play down to 30Hz, according to Wesayso in his thread... with EQ of course.

Also, a flat FR up higher to 18kHz is not the best, as line arrays will have more interaction at HF and you will lose some of it, so a driver with a rising FR is often more recommended than a flat one.
 
Last edited:

fluid

Member
2009-01-24 2:20 pm
well, the drivers are rated +/-3db from 45hz to 18khz. and everything i've read about comb filtering is that the reality is it's not audible if the drivers are edge to edge.
That is not a useful spec without a response curve it is almost meaningless, the centre to centre spacing of drivers determines the frequency at which combing will start and you want that to be as high as possible so you want to use the smallest driver possible everything else being equal.

Do you have a link to the driver you have as some of the most important information is missing. Any driver with an Fs of 45Hz is going to be quite large and the combing will start lower.

If you move the combing high enough and listen far enough away (2m plus) to actual music rather than pink noise, then it is not an issue, but that is not the same thing as thinking you can put any driver edge to edge and not have an audible problem.

The reason why the TC9 works in this application is because it's size and parameters work to allow it be used truly full range.
 
unfortunately, i can find no more info regarding this driver than what i posted. here's a link to an old parts express page:
Peerless India LKO-120WFF 5-1/4" Fullrange Driver

thanks,

doug s.
That is not a useful spec without a response curve it is almost meaningless, the centre to centre spacing of drivers determines the frequency at which combing will start and you want that to be as high as possible so you want to use the smallest driver possible everything else being equal.

Do you have a link to the driver you have as some of the most important information is missing. Any driver with an Fs of 45Hz is going to be quite large and the combing will start lower.

If you move the combing high enough and listen far enough away (2m plus) to actual music rather than pink noise, then it is not an issue, but that is not the same thing as thinking you can put any driver edge to edge and not have an audible problem.

The reason why the TC9 works in this application is because it's size and parameters work to allow it be used truly full range.
 
Doug, you are still missing the point of driver size.

C-to-C is the distance between the centres of two drivers.
You will want that distance to be as small as possible.

People get away with it by using smaller drivers 2" to 3", and with a rising FR response.
If you really want to use a 5"+ driver, consider adding an array of tweeters too.
 
will do; thanks.

doug s.
Doug, you are still missing the point of driver size.

C-to-C is the distance between the centres of two drivers.
You will want that distance to be as small as possible.

People get away with it by using smaller drivers 2" to 3", and with a rising FR response.
If you really want to use a 5"+ driver, consider adding an array of tweeters too.
 

fluid

Member
2009-01-24 2:20 pm
unfortunately, i can find no more info regarding this driver than what i posted. here's a link to an old parts express page:
Peerless India LKO-120WFF 5-1/4" Fullrange Driver

thanks,

doug s.
That does not look like a good candidate for a full range array. The cabinet wiring and associated effort in building a full range line array needs to be based around a good driver to make it worthwhile. IMO that driver is not worth your time as the result will be disappointing and not at all representative of what a properly executed full range line array can deliver.
 
thanks, chris.

but either i'm not doing it right, or something's screwy about the figures i'm getting. (the only data i plugged in that i'm not sure about is 6.33 ohms for "series resistance" in the "signal" tab, after i've loaded all the driver perameters. but this is the resistance i'll get when running 3 sets of 5 series'd drivers in parallel.) anyway, for anywhere from a 4 to 12 cu-ft sealed box with 15 drivers, i'm getting -3db at 42hz and -14.5db at 20hz. is this because it's not eq'd at all? it seems that would require quite a bit of eq to get flat at 20hz, even w/15 drivers.

however, i'm assuming that's supposed to be ~91db, as the "signal" tab says it's at 1w, and that's the spec of the drivers. but i'd think 1w would generate significantly higher spl w/15 drivers? does this really mean it's at ~102db, w/a doubling of drivers equal to an additional 3db? so, 14.4db down at 20hz would be 87.5db? if i added eq, for flat to 20hz i could get max steady spl's at 20hz of just over 100db, w/peaks of just over 103db? (16w would give 99.5db and 32w would give 102.5db? drivers are rated at 20wrms; 40w peak)

(if i run the program with a single driver in a 1.1cu-ft box, 4 ohms resistance, i get -3db at 51hz and -15.2db at 20hz, again assuming ~91db, w/1w)

and, if the above is correct, in reality, i'd only want them flat to somewhere between 50-80hz, as they'd be actively crossed to subs at 24db/octave, which means i wouldn't need any eq except to extend the treble as they're rated flat to 18khz...

thanks for putting up w/a total newbie when it comes to this,

doug s.

You're not doing it right.

Don't put anything in the "series resistance" bit. Maybe half an ohm if you've got really long thin cables.

The numbers I gave you are the maximum output of those drivers - when you put a driver in a sealed box, the maximum output is easily predicted, using cone area and Xmax.
When you EQ, all you're doing is telling the amplifier to put more power in at some frequencies than others.

Chris
 
i've heard line sources, and i think they're fantastic - if they're not open baffle. most dipoles i've heard create an overblown diffuse soundstage that is not my cuppa. my room is ~26x38x8.5, so i think a line source speaker would work very well. i'm fortunate to have a large room; i've had quite a few different speakers in the system, and it would take a really mediocre speaker not to sound at least decent in the room. having a pair of actively crossed over vmps larger subs helps.

doug s.
Doug, never having built one - probably due to being less than overwhelmed with the couple of samples I’ve heard over the years- I can’t help but ask if you’ve had occasion to hear a well executed line array in a room similar to what you envision you’d have available for this project.
 
thanks, chris.

if that's the only issue, it's an easy one to correct. i'll try it and see what happens. my speaker cables are 8', and not exactly what i'd call thin. but maybe i should use something like 1/4 or 1/2 ohm instead of nothing, due to the fact that wiring up a line source takes more than the usual amount of internal cabling?

re: eq, i understand how that works; i was just trying to confirm what the spl output would be with 1w input, as the winisd program doesn't specifically state what its output is.

thanks; this info is useful even if i end up building a line source w/different drivers.

doug s.
You're not doing it right.

Don't put anything in the "series resistance" bit. Maybe half an ohm if you've got really long thin cables.

The numbers I gave you are the maximum output of those drivers - when you put a driver in a sealed box, the maximum output is easily predicted, using cone area and Xmax.
When you EQ, all you're doing is telling the amplifier to put more power in at some frequencies than others.

Chris
 
...never having built one - probably due to being less than overwhelmed with the couple of samples I’ve heard over the years- I can’t help but ask if you’ve had occasion to hear a well executed line array in a room similar to what you envision you’d have available for this project.
Chris - allow me the curiousity to ask what kind of systems you have listened to? How tall were they, size of driver and qty of them?

I am NOT trying to debate your experience, simply curious on the data mentioned above. Can you elaborate?