515E for integral sub in 828 cabinet

[RogerR]

Would the Altec 515E LF driver be suitable for use in the subwoofer bi-sectioning scheme with 825/828 cabinets? I have read all the past posting on this subject but I am still uncertain if this would be a waste of these particular drivers. My cabinets have been reinforced and the horn flare cavities have been filled.I currently use 515G drivers with a smaller than standard port.

[taudo]

Roger,

I've just decided to go down this road, too, and have used the search feature to pull up all the old threads on "subwoofer". It seems that the consensus of opinion is that 515/416 drivers do _not_ make good subs. A number of folks have suggested JBL 2245's, Altec or Iconic 3182's, and Altec 411's.

I have no personal experience (yet!) with any of these drivers, but did perform a proof of concept experiment using some low end separate subs that surprised me pleasantly (see "Re-porting 825/828 cabinets"). Clearly, adding subs makes a big positive difference. With a separate amp for the subs, matching the efficiencies shouldn't be a huge problem. At this time, I plan to use Rane active crossovers which also allow time-aligning the drivers (which are physically offset in the 828 with integral sub).

Good luck and keep us updated on your progress!

taudo

[WV]

taudio,

when you say, the 416 is _no_good_sub_ i have to raise my finger.

I use a cabinet with two 416-8C as a compound system. The active X-over is a JBL Urei 5235, the turnover frequency is 50 Hz. Above these 50 Hz i use the A7-500.

http://www.vallieur.de/wolf_boxen_2.htm

They have really different SPL's (sub and A7), but driven active this is no problem.

I think that subwoofer is a good completion of the A7 and i don't want to miss it. The bottom of that system is great and can shake the house, if i would like to.

I never would take the 515X-series for a subwoofer but the 416X are (in right enclosue) great sub's IMHO.

Best
Wolf

[taudo]

Wolf,

Now, what finger are you raising there, pardner? ;-)

Actually, I'm intrigued by your use of 416's as subs - I've got extras of those but no 2245's! I went to your website and it is quite interesting. Unfortunately, I don't speak German [old joke - what do you call someone who speaks two languages? Bilingual. What do you call someone who speaks many languages? A polyglot. What do you call someone who speaks only one language? American.]

Anyhow, could you provide a bit of technical info on your 416 sub design? It looks quite interesting!

Thanks!!

taudo

[WV]

taudio,

that sub was built by myself; it's a cabinet with round about 360 litres (12,7 cft) and it is designed to be placed under the billard table.

The peak is about 32 cps. In comparison to the A7 that box needs a lot of power and i think it should only be driven active. Compound systems have about 3dB less than two driver in normal position. But in compound system the drivers control one each other and the sound is clear and without distortion. That makes that sub being the right partner for the A7.

I mounted 4 reflex pipes with about 19 cm length.

First i thought using that box only with beamer, hearing 'HiFi'-music only with the A7. In the meantime i don't like to miss that sub with every music, including classic and shurely rock.

Thank you for your interest, i am proud about that box.

Best
Wolf

[GM]

>Would the Altec 515E LF driver be suitable for use in the subwoofer

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No.

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>when you say, the 416 is _no_good_sub_ i have to raise my finger.

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As a single driver in this app it isn't.

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>I use a cabinet with two 416-8C as a compound system.

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When it comes to 'collectable' drivers, I don't think in terms of 'wasting' them for these types of apps, but if you already have them or can get them 'on the cheap', then yeah, all sorts of driver options become available.

Carrying this to the next level, you can make them sealed and use a L-R transform to electronically dial in the final sysQ/BW, with power handling and your finances being the limiting factor.

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>Compound systems have about 3dB less than two driver in normal position.

====

Actually, the performance is the same as a single driver, so a 6dB loss in voltage sensitivity, but twice the power is required. Not many 'free lunches' in audio and a waste of some good drivers unless small is a primary performance goal and you already have them.

Anyway, if the extra cost/effort of compound loading is acceptable, then four Adire DPL12s in dual compound aperiodic cabs/channel should get you down to 7-8Hz with some authority if your room/house is very well constructed.

With ~2.5kW on tap, playing the space shuttle launch CD should get a rise out of your neighbors, all of them. For the truly demented, use NorthCreek Leviathans/>3kW instead. Probably not a good idea if you live near/on a fault line though.

GM

[WV]

GM,

>Actually, the performance is the same as a single driver

That's why i think you loose about 3dB of power.

MAy be you are right, compound can be a waste of good drivers; i drove that cabinet with EV 15B, too, with nearly the same result. But of all of my cabinets (and i had several) this one gives me the lowest bass.

This bass-cabinet is only the lower basement of the A7.

>Anyway, if the extra cost/effort of compound loading is acceptable, then four Adire DPL12s....

Do you have some construction plans and more details? I am interested.

Best
Wolf

[GM]

No, I just did a quick sim. Basically, you build two clamshell loaded ~2.5ft^3 cabs (net) tuned to ~10-16Hz (depending on your preference) with a 15" PR in a common box with the outside drivers/PRs in a bipole layout so that their vibrations are ~cancelled out. Stuff them with ~2.5lbs of R19 fiberglass insulation to increase effective Vb ~1.2-1.4x, or just build bigger boxes.

GM