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How can I improve the bass a little ???

A woofer similar to those used in Klispch speakers with EV drivers used in Speakerlab speakers? Sounds like a decent home-brew.
 
kfa888 may be on to a possible problem with the cross over as the mids are quite loud and in your face. But im afraid that designing and building a new crossover is waayyy beyond my level of competence. I do happen to have a 15" powered subwoofer that I could add to the system and just let the 15" woofers be kind of a midbass but that seems kind of like the wrong way to go as I think the stock units should be performing better than they are at present. Anyone think of a solution a novice could accomplish???
 
Here's what I see: The picture shows what looks like a large gap around the bottom of the mid horn. If so patch it and add foam tape around the drivers and cable connector block to be sure there are no air leaks. This is critical even on ported speakers. The patched in oval cut out, looks to be not properly sealed. Check these and the cab joinery itself for air leaks.

At a given tuning, the larger the port area, the longer it must be. This is a large port and it is going to be tuned quite high, so no low bass. Even with a poorly matched driver, you can go a long way by getting the port right. Find the internal volume of that cab so we can help with the tuning. The cab looks big, yes, but the triangular shape cuts the volume in half from a rectangular design.
 
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Thanks for the reply John. The pics are a bit misleading in that the front stain was done with the drivers in place and taped off, so everything is well sealed and the cabs are well sealed. In the oval patch section, just the 1/16" very top layer of the 3/4" plywood has lifted a bit, the plug is solid.
The interior diminsions are: Front-42" tall, 34" wide. The sides are each 24" wide and 34" tall. The port is also made out of 3/4" plywood and is 15" wide, 3" high and 6" deep. The interior walls of the cabs are about 1/3 covered with a thin 1/4" fiberglass padding. Nothing else inside the cabs except the backs of the drivers. Can one figure the volume from this info???
 
Okay, I did some calcs. The cab volume would be around 5 cu. ft. (including subtracting some space for drivers, port and bracing). Given the port size, the cab is tuned to around 46Hz. Considering corner placement and room gain should be getting bass extension down into the mid to upper 30s which covers most music. This will depend on the driver.

If it were me, I'd tune these big cabs down to 35 Hz, but this means a 14" long port and the slot won't fit the cab shape. You'd have to seal that port and use a narrower one that can reach deeper into the cab.

Like I said, check these cabs for air leaks as you should be getting bass as they are. Leaks will KILL your bass as they wreck the pressure needed to setup the cab and port resonant system.
 
Okay, Ignore much of my last reply as leaks are not a concern and I was basing my calcs off of incorrect data. With these numbers, you have around 6.7 cu ft of internal volume. With that port, the cab tunes to around 40Hz. You should be getting in room response down to high twenties/low thirties. Big ported cabs are efficient bass makers, so sounds like your problem is elsewhere. Even with a mismatched woofer driver, you still should be getting something.

These speakers should handle about any music. If your after home theater bass (very deep), you will have to tune the cab lower and (perhaps) get a driver with a lower tuning (Fs), but this is at a cost of some higher bass efficiency. What are you after?

Did you check phasing? One wire connected reversed to the other cab? Amp settings, room modes (listening in a weak bass area)...?
 
Where are you running the tweeter and mid controls(L-pads)?

The woofer will naturally have a good bit lower sensitivity than the mid and tweet. If the mid and tweet controls are turned up too high, the resulting imbalance in sensitivity will create the perception that the speakers are mid/HF heavy and bass shy

EDIT: you might try an email to the tech dept at Eminence with the 15QFHS8G part number, they might be able to provide some parameters or other info. But, the date code indicates the woofers were made in the 2nd half of '77, and Eminence might not have data going back that far.
 
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Thanks for the help John. I see what you mean in that the longer port would hit the back of the cab before seating into the front face. I will go over the cabs carefully and check for leaks. The speakers are located at the end of my three car garage and sit on their built in 3" platform foot. so very hard surfaces involved compared to inside a house. one other thing I noted while inside the cabs; they used very thin solid core wire internally, almost like door bell wire rather than the normal stranded type wire. As near as I can tell these speakers were built in the early 80's. Thanks again John and everyone else, for the input. Guess I will just have to play around with them see what happens but I have no idea what else to do other than just replace the woofers and see what happens (expensive trial and error!!) or mess with the crossovers (no expertise there). I should have studied EE rather than Business in college.
 
Did not read the above two posts before posting my last post. This is in a garage stereo set up, no HT envolved. As I said, I am getting some bass but just not enough. I would think those speakers should put out killer bass. The darn trb/mid controls are on the bottom of the speakers under the foot, have to turn them on their side to get to them--PITA. for an old man. I have them set at about half way. I am careful about phasing but may have to get back into the cabs and check the wires inside since I did reinstall them after the woofers were re-foamed.( Not that I could possibly do anything wrong-Ha!!!) but they have never had really heavy bass.
 
My guess is that those are NOT the woofers those were originally built with, probably "close enough" replacements. My further WAG is that the boxes are totally wrong for that type of woofer, and their sensitivity is much lower, and compliance much looser than what would be ideal for that size box and tuning. You could probably pad the mid and tweet wayyyyyyyy down and get a reasonable balance at the cost of a LOT of sensitivity. But, if you want to fill that space with the kind of bass that those should, you're going to have to put woofers in them that are made to do that job.
 
I listen to a lot of bass heavy blues/blues rock music so bass is important to me. If move the cars out and put on Dire Straits "Money for Nothing" and crank the volume up these things will just rock !!!! Same with Steely Dan's "Do it Again" But generally speaking, with the volume turned down a bit they are not that good in the lower end. I am using a Onkyo 100watt integrated amp, ADS equalizer, Denon CD player.
 
bowtie427ss, I can replace the woofers but with what ??? Can someone give me an idea of which ones to use and where to get them???
 
I'd leave the port alone if HT sound isn't desired. If everything else checks out then I would agree that it is time for a set of PA drivers. Good ones aren't cheap, so I'd recommend that you ask one of us to match them to the cabs before dumping the cash.
 
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