3 Way build, looking for low end driver.

Vizi0n

Member
2016-04-09 8:15 am
Hey all, hoping someone can point me in the right direction. I've asked around a few other forums and gotten responses on both ends of the spectrum. My original plan was to use some parts laying around from other projects that never got used (selenium D220ti, eminence delta 10a and eminence delta 15LFA). I've since decided to buy a better CD, but I'm fighting myself on which driver to use for LF. I was recommended the 2226H to replace the 15LFA, but seeing as it's more of a midbass driver, it just doesn't get quite as low as the 15LFA (at least in my models with bassbox/winisd), but I also know the lfa has it's fair share of shortcomings in a vented box which is why I'm looking for a replacement.

I guess what I'm looking for is a 15" driver that comfortably gets to 40Hz with low enough qts to work well in a vented box. Price isn't a HUGE deal but obviously lower is better. CD/High output build as well, so it is worth noting I want to keep it around the sensitivity of the other drivers (B&C DE250 and Eminence Delta 10)

Anything helps, and thanks ahead of time!
 

AllenB

Moderator
Paid Member
2008-10-18 11:31 am
The delta15 has a sensitivity of around 96dB/W/m which is much lower than what you'd probably get from the tweeter, otherwise they aren't a bad woofer. Going for a more extended bass will, broadly speaking offer worse sensitivity. A better approach might be to consider using subs, not as a compromise but as an improvement. You could even use smaller drivers as subs.

With a little care (and a lowish crossover point) you could even cross the Deltas straight to a good compression tweeter and waveguide.
 
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Vizi0n

Member
2016-04-09 8:15 am
I am planning on using subs for HT use, actually already have those planned out - no problems there. Though a major part of these cabs will be 2ch music and I want to get as much out of them as I possibly can for that purpose. They're definitely going to be actively crossed over, just haven't decided on whether I want to use a driverack or another xover laying around. You think the delta15 will be solid in a vented box tuned to 40ish Hz w/ hpf at 30? If these are okay, is there a driver you could recommend that would be better still for this purpose?
 

AllenB

Moderator
Paid Member
2008-10-18 11:31 am
These woofers can be crossed as high as 1200Hz with care, though 600Hz makes an easier job of it. You need to think how you'll match them to your tweeters. Since the 15" woofers begin to beam in the midrange they can be used to match a waveguided compression tweeter with a crossover point somewhere within the above range. The 10" driver would require a higher crossover point to do the same, and since the tweeter can be used to cover a critical part of the spectrum alone it might be worth specifying how you plan to use it and working down from there.

Your room will be dictating the bass performance to a considerable degree, especially in the sub 100-200Hz region. There is some reason in having a woofer cover solidly down to 80Hz in order to overlap the vocal region, but at the low end the room is a complication that subs can help with because you can position them wherever they will help the most.. Broadly speaking if it were my choice I'd be more likely to use the Deltas in a closed box.
 
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AllenB

Moderator
Paid Member
2008-10-18 11:31 am
The main difference between an active and a passive crossover is the way you implement them. Their capabilities are essentially the same. But a crossover is as much an acoustic concern as anything, eg the way you baffle, the size of the radiators and where you position them. An electrical filter can not make a bad combination sound good. This is why I suggested you consider what you were going to do with your compression driver.
 

Vizi0n

Member
2016-04-09 8:15 am
I'm not sure I understand the concern. Is the concern for the difference in sensitivities between the compression driver and the other woofers? I mean what does anyone do in that situation? I was just planning on giving it significantly less power or pad it on the xover. Is there an issue with this?
 
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AllenB

Moderator
Paid Member
2008-10-18 11:31 am
For arguments sake, lets say the tweeter spreads the sound wide and the midrange cuts in with a more narrow beam, and you then adjust them so the direct sound is balanced. You may find that the background has an excess of treble, and that the sound you hear reflected from the walls comes from the tweeter alone which may be distracting. There may not be a correct setting.

You control this using the dimensions of the speaker, and how you use the baffles. You try to keep it smooth from treble to bass, even if it changes from one to the other. When you cross you want to try not to interrupt that smooth transition.
 
Allen is right of course and this will seem quite complicated to calculate.

Things get a LOT simpler if you pick 90deg as your desired dispersion.
There are plenty 90deg horns about but mostly a cone driver beams roughly at 90deg when wavelength = driver diameter.
For a 10" that would be about 1400Hz. Right in your target range.

For the 15" question I quite like FaitalPro drivers and every one of their 15s should reach 40Hz easily.
http://www.parts-express.com/cat/pr...eca:matches(.,"P_Searchable","1")]&PortalID=1
 
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Vizi0n

Member
2016-04-09 8:15 am
Thanks, that makes a lot of sense and it's something I hadn't really considered. The waveguide I was planning on using is the seos15. I'll check and make sure everything works out correctly. Is there a formula for this or do I just have to find the information for each driver somewhere? Or measure it myself. Also I'll take a look through faitals catalog.
 

Vizi0n

Member
2016-04-09 8:15 am
I've still been looking around, and it seems like the 4015LF would be a perfect fit for me in place of the Delta 15, even models out how I want. But all the threads I can find on it are for tapped horns. Should I avoid this driver for a vented box, or will it work well there too? What about this driver makes it so attractive for a TH?
 
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AllenB

Moderator
Paid Member
2008-10-18 11:31 am
The seos15 is claimed to reach 950Hz although I'm not sure I wouldn't cross it comfortably an octave higher. Although it may be 15" wide its height is half that and it narrows somewhat above 1kHz.

The crossover point should consider this capability of the tweeter, and the woofer size with this kind of speaker should be chosen based on said crossover point.

This would mean using the woofer as a direct radiator, not a tapped horn. Closed or vented will work. Closed is not chosen any less than vented is, going vented has its pros and cons.