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Where did the bass go?

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How can I improve my bass response in my 1964 Khorns? I recently replaced my K-33-J (Jensen P15LL) woofers, due to a rubbing voice coil, with new K-33s. The K-33-J has amazing bass response, but the new K-33s are lacking in volume level, depth and low frequency reproduction. I thought that maybe the problem was that the bass bins were not tight as some of the gasket was slightly damaged when removing the dog house door. All gaskets were then replaced, and the results are the same. Any suggestions or comments will be appreciated. Thanks,

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The replacement woofers are new, very few hours if any. I wondered about a break in time for woofers, but could not find anything of value on Google.

Thanks, I have seen good write ups on the old alnico K-33-J woofers, and now I believe it to be true. The Jensen P15LL woofers are great. I may get the damaged unit repaired, but I fear that it will never be the same.

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Regarding breaking them in... I once asked Roy (Delgado) about that. Though I do not remember his exact answer it was something like "yeah, we break 'em in.... we connect them to "X" volts for about 20 minutes and then consider them done"

I don't remember how much power. I was surprised that it was approached with such a casual thought. I sometimes wonder if we (the public in general) worry about some of these things more than the people on the other side of the fence (manufacturers) worry about them?

Regarding getting the Jensen repaired.... I would sure like to think it could be put back to original spec. Can you send it to Jensen themselves? (are they even still around?)

I've got some old EV woofers that I had EV refoam once. They don't do these anymore so I'll have no choice now but to do it myself or (more likely) have someone else do it and keep my fingers crossed.

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I am assuming the placement is the same as before etc. Is it just the deep bass or is it "all the bass"?

I agree that out of phase wiring is a possibility. Other possibilities include: 1) the cabinet is no longer tight into the corner, 2) the access hatch for the woofer is no longer air tight. IOW, was the gasket in good shape, forming a good seal, and the door tightened securely? 3) Was there any chance that the wiring on the crossover was inadvertently changed during the removal and replacement?

I would check those possibilities first before you get side-tracked on "breaking in" the drivers.

Good Luck.

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Thanks to all who offered advice. I do hope that the speaker response will improve with time and use.

The big difference is the impedance, the new woofers are 3.7 ohms. The old woofer with the rubbing voice coil is 2.7 ohms. I believe that this would allow more current (power) to pass through the woofer, hence sound louder.

I have triple checked everything and replaced the seals. The bass door panels are sealed tightly, the motor board is sealed well, and all panels are tightly secured. Phasing is correct and also verified with a phase test track on a testing CD.

The Khorn is tightly sealed against the walls with pipe insulation. Still the bass is not as loud, I will continue to use and pray that time will heal all.

Thanks again,


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