Problem with subwoofer (not performing like it should)

[chris661]

Is there anybody nearby (on this forum or others) that could come around and have a look?

 

[andyba55face]

Is there anybody nearby (on this forum or others) that could come around and have a look?

I don't know, but I know a guy that owns a local radio shack and he's got some test equipment so I'm going to bring it to his shop today and see what he can tell me. I'll post what happens later.

 

[weltersys]

Luckily I do have a spl meter and did a test. I turned my mixer/preamp up high and then turned the gain knob on the crown about 3/4 way up before the sub started distorting and sounding bad. The spl meter was reading about 85-95 db at this point, depending on which part of the song was playing. The meter on the crown was about -20 to -10. It was running on stereo bypass mode. This was free air outside the enclosure.

Andy,

What is "stereo bypass mode"?
What scale were you using on the SPL meter?
What distance from the sub?
How much louder is the speaker in the cabinet than free air?

Art

 

[rho]

Free air, outside the enclosure, you should get lots of excursion and not a lot of sound pressure. That's what I would expect.
With the speaker in the box, the excursion should be much less (near the BR tuning freq.), with lots more output.

Also, answer Art's questions.

 

[andyba55face]

Free air, outside the enclosure, you should get lots of excursion and not a lot of sound pressure. That's what I would expect.
With the speaker in the box, the excursion should be much less (near the BR tuning freq.), with lots more output.

Also, answer Art's questions.

I agree Rho, however my speaker is not working this way (how it should)

 

[andyba55face]

Andy,

What is "stereo bypass mode"?
What scale were you using on the SPL meter?
What distance from the sub?
How much louder is the speaker in the cabinet than free air?

Art

Stereo bypass mode on the crown amp is sending the full range of frequency to the speaker. The 'scale'? Idk just whatever scale would let me get a reading. Distance was about 2-4 ft. from the sub didnt' make too much of a difference in spl. The speaker doesnt sound much different in the cabinet than free air.

 

[rho]

Are you used to listening to very loud bass (in your car for instance)?

I've participated in dB-drag racing competition some years ago. I can tell you that the first months, when listening to home installs I didn't notice any bass where others thought it was quite loud. It took a few months to "recalibrate". (no permanent hearing damage in that area tough )

 

[weltersys]

Stereo bypass mode on the crown amp is sending the full range of frequency to the speaker. The 'scale'? Idk just whatever scale would let me get a reading. Distance was about 2-4 ft. from the sub didnt' make too much of a difference in spl. The speaker doesnt sound much different in the cabinet than free air.

If you were using "A" scale, the SPL meter rolls off below 1000 Hz.
The sub won't put out much level above 1K, 95 to 105 dBA sounds quite normal for the way you measured.

Have fun, good luck.

 

[tb46]

Hi Andy,

Have you by now measured the drive voltage @ the speaker terminals? Even the cheapest AC voltmeter will give you reasonably accurate results @ 50-60Hz. Also, don't make free-air sinewave measurements on loudspeakers until you know exactly what you are doing, that's one of the quickest ways to ruin a driver.

Regards,