Bass Lag

[BassAwdyO]

Lets see.... My port is 8 feet long with 4 bends. 2 of the bends are 90 degree and 2 180. Its not that it's the cleanest or best sounding bass in the world, but its definately something anyone could tolerate listening to and would enjoy.

 

[Retsel]

If the sound from the subwoofer is truly nondistorted, then you simply need to move the subwoofer closer to the listening position relative to the main speakers and your problem would be solved. My Genesis subwoofer is very adjustable with adjustments for the phase angle. By making adjustments to the phase angle the sub is brought in or out of phase allignment with the woofer of the main speakers. If that does not solve the problem then you are dealing wth a distortion issue.

To solve a distortion problem, of course the driver must be mounted in the appropriate box because if it is not as this would cause the driver to be overdamped and not correctly reproduce sound, especially at the frequencies near the slope which is the most difficult for larger drivers anyways.

However, other questions are: what is the quality of the driver and at what frequency are your crossing over the driver and at what slope? I am sure that the driver has no problem reproducing bass at lower frequencies it if has X-max. However, it may have a difficult time and may be distorting at the higher frequencies if you are using a low slope crossover, the driver's magnet is too weak and the cone too heavy.

Retsel

 

[Bill Fitzpatrick]

Hmph.

 

[richie00boy]

Moving a sub to address phase is not necessarily ideal in practice because subs interact so much with the room. Therefore it may be in perfect phase but sound awful due to the room modes.

 

[Kranis]

Hey guys, what's up? I've been reading diyaudio for a while now - over a year, a lot actually, and have a question to ask. In fact, this is something that I have never seen discussed in my travels as far as I know.

I bought an Eclipse 12" DVC subwoofer from a reputable home/car audio store, which also suplied plans for a vented box for use in a home environment based on its T/S parameters. The thing is ridiculous in terms of output, but it has a problem: the bass lags. When I listen to dance music or rap, the bass out of the subwoofer actually hits a few fractions of a second after the mains. Well, to be honest the beat "ebbs" as much as "hits" out of the speaker, but it makes it impossible to enjoy these types of music! What's up with that? Has anyone heard of this? Although I have not calculated SQL or system Q (as if it was a sealed box), I didn't post the T/S parameters because I have a feeling this phenomenon is not related to box size or tuning frequency - the sub has been in three different boxes with different parameters and it exhibits the same phenomenon.

Can anyone help me solve this problem? Thanks for all your help,

Philip

Given your posting of the T/S parameters and box design, I think it is pretty clear that your design suffer from a high q-value, which means it is very resonant. The phenomenon you are describing is present many home theatre subs where timing isn't that critical - the LF channel mostly provides rumble anyway. To use such a sub for music reproduction will not work unless you have a high tolerance of lagging bass. As already have been indicated - your driver is not really suited to be in a box, especially not in a vented one. The comment above is only about the resonant behaviour of your driver. Cascaded filter functions (with steep slopes) can also introduce a time-lag between sub and fronts that is audible, but that is another story I think.

/Kranis