EQing the 340SE for ultra low bass?

[davef]

Hi Guys,

Good discussion here ---

As you know, the 340 SE is a ported speaker with an approximate port tune of 48Hz. As you move downward in frequency and approach Fb (port tune frequency) the woofer moves less and the port does more work. At Fb, the woofer has the least amount of movement (which is why I like ported speakers because there is a dramatic decrease in THD, IMD and mechanical noise from the woofer because it has much less movement than a sealed enclosure from Fb and higher)

As you move below Fb in frequency (less than 48Hz), the woofer is essentially unloaded from the cabinet and acts almost as if it is operrating in free-air (no cabinet). There is excessive movement.

Boosting frequencies below Fb is a *very* bad idea. A 3dB boost is twice the power, which will cause an increase in cone excursion by approximately 50%, which will degrade all other frequencies the woofer must reproduce. Essentially, you will be boosting the low end response at the sacrifice of mid-bass and the delicate midrange frequencies.

In addition, port noise, while normally not an issue, will potentially become a problem as a 3dB boost will increase airspeed in the port by 50%.

Honestly, the best option would be to add a small sub and roll off the deep bass signals being sent to the 340 SE. This will improve the performance of the loudspeaker by reducing all of the artifacts I mentioned above. Best of both worlds -- deep bass -and- clean and accurate mids

Hope this helps!

[SteveCallas]

add a small sub

Wait a second, why does it have to be small?

[GirgleMirt]

Thanks for the info! Well when you put it like that, it doesn't seem like a very good idea anymore

[JeffD2]

This thread was a great read. Thanks everyone.

David, your system sounded magnificent when I heard it. I can't imagine how good deep movie material will sound with a higher end sub! Good luck on the upgrade.