Are the ports to big

[Integrexman]

I made these cabinets in 1990. The driver is a E140. I don't remember how I calculated the port area when I made them. The internal dimenstions are 22.5 wide, 23.625 high, 15.5 deep. That equals 4.77cu.ft.

I think I made the ports to big they are very efficient but have a hard time getting low end out of them. I know 40-50 is about the lowest the E140 would go but I have to EQ 63-100 up more than I think I should. Can anyone tell me what the area of the port should be with this cabinet/driver combination and how low I can expect to go.

Thanks, Keith

[duaneage]

I think your box is too big for the E140. Your trying to get bass froma speaker not known for bass in a vented box. It's a great speaker but not the best for this application.

The ports look to be 2 x 3 inches, that would be 52 hz in that box give or take a little. Your looking at serious delay in the range your trying to get bass out of the driver. I would suggest using a bass driver, something that works in 4-5 cu ft and has the right type of suspension for the job.

[Integrexman]

Sorry I forgot, the ports are just a little over 4" in Diameter. The baffle is 13 ply birch so around 11/16" thick.

[duaneage]

They are really tuned in that box to 62 hz. Try plugging them both for starters.

For a vented alignment the best result is .65 cu ft , 4 inch vent (only 1) 6 inches long and that is tuned to 77Hz.

Your not going to get knee bending bass from this driver, it's just not there.

Try and fill the volume up inside the cabinet, plug one vent, and use 6 inches of PVC, see what happens. Books, magazines, blocks of wood, anything solid and non compressible

Good luck.

[duaneage]

Here are few alignment suggestions. Yours is in blue. Red and yellow are probably your best bets, since they produce the best group delays and protect the driver from excursions.

Big boxes can be expensive, but the E140 can take it. I think that driver is more of a horn loaded system beast IIRC.

[duaneage]

And by expensive I mean for recone kits. This group delay graph gives an idea of what a driver in a big box is doing when it hits the port resonance. While not exactly excursion results, you can see a marked difference compared to more optimum alignments. Some drivers are meant as really good midrange drivers (read guitar speakers) while others do duty as bass drivers. The suspension on your driver is probably tight as hell, not really very compliant. A bass driver will be very loose, it depends more on the box for support.

[Zilch]

JBL used that driver in Cabaret Series boxes about the size of yours tuned to 40 Hz.

Go to the hardware store and get a pair of 4" plumbers' test plugs to block one of the ports in each of your cabinets. That'll tune them to ~39 Hz and you should hear much improved bass response. You're presently tuned to ~52 Hz.

If you like that result, then because your vent velocities will get high at high SPL, you'll want to keep the two ports in each box open instead by adding ducts, 2 x 4" @ 4.57" or 2 x 3" @ 1.61". I offer the 3" option because it may be easier to just make those on plywood squares and install them in your existing openings from the inside.

BB6P suggests tuning even lower, 34 Hz, using duct lengths of 8.15" or 3.54" for 4" or 3" diameters, respectively. Group delay is highest in this alignment, but peaking at 16 ms at 34 Hz, it's still within acceptable limits.

E140's not an extended bass woofer. That's about the best bass you'll get out of them in those boxes, but it's certainly better than what you are presently getting.

Check my calcs, please....