[Wind Chaser]

Looking at Danny's website comparing the MX130 to the M130X, it appears that the M130X requires 3X more volume to produce the same bass as the non XBL version... 

"In a .40 cubic foot ported enclosure it (the M-130 woofer) will play to a -3db down of 55Hz."

And the M-130X with the XBL2 motor is "-3db down point in a 1.2 cubic foot ported enclosure is 55Hz."

What's the scoop?

[Danny Richie]

You must have input a spec or two wrong. They both need about .4 cubic feet of air space ported. Make sure you didn't type in volume in liters when it is set to a US measurement.

[Wind Chaser]

Those are direct quotes from the GR Research website taken from the page of each respective driver.  The M130 being HERE; look at the bottom line of the second paragraph - and for the M130X HERE notice the second paragraph.  It reads as follows, "This woofer has incredibly smooth midrange and very good low bass extension. -3db down point in a 1.2 cubic foot ported enclosure is 55Hz.

You cannot blame that error on me!   I did not write that. Based on your previous post, the page detailing the M130X needs to be corrected.  But that leads to another question...

[Danny Richie]

Ah, I see where you got that now. That is one of those cut and paste error from when I had info on the M-165X page and copied into the M-130 page and failed to correct that part.

Thanks!

I just corrected it.

Now what was your next question?

[Wind Chaser]

How big a box is required to get the M130X down to 40Hz or there abouts?

After the NY October Rave, Al got some feedback on the OB2X stating..."cabinet resonances interfered with the bass which was too loose and boomy."  In an attempt to correct this problem the participants plugged a towel into each of the ports.

Al responded by stating... "the cabinets that were sent for the NY Raver's were just plain square cabinets with limited braces in them all for weight and easy of shipping. ...the XBL drivers need more air which also came out in the speaker shoot out for the RAV1X as well.  Both designed cabinets were on volumes which were made for the non XBL drivers... ...in both cases the cabinets need larger volume's..."

If I understand the above, it seems the M130X requires more volume than the M130 to produce the same bass, but now it seems that may not be the case?

Not trying to be difficult here, but I did buy the actual units that were at the October NY Rave.  I am planning to rebuild them in a much more eye appealing and thicker enclosure, so correcting the bass issue would be nice.  I will also add No REZ and upgrade a number of the crossover parts from your website, possibly putting them in separate outboard chasis.

[Danny Richie]

The shape of the cabinet might have had something to do with it too. If I remember correctly the depth was pretty shallow. But the bracing (or lack of) may have had the most to do with it. Placement might have been another issue with those as per that get together as well.

You can up the box to .45 cubic feet and tune it to 46Hz to get a -3db of 50Hz.

[Wind Chaser]

You can up the box to .45 cubic feet and tune it to 46Hz to get a -3db of 50Hz.

.45 cubic feet would equal 777.6 square inches/almost 100 square inches less than the current enclosure which is internally measures 26.5" X 5" X 6.5" for a total of 861.25".

Are you able to speculate/predict what would happen if I made the cabinets 1200 square inches/bigger with and without the port?  And does the space the No REZ occupies have to be considered in order to attain the final volume?

[Danny Richie]

Are you able to speculate/predict what would happen if I made the cabinets 1200 square inches/bigger with and without the port?

I don't just speculate. I model it in some software that is pretty good about being really close to actual measurements. .69 cubic feet would cause it to loose output from 100Hz and down. -3db in a ported enclosure that big drops to 41.5Hz. Power handling drops quite a bit though. It is especially unloaded in a sealed box that big and would bottom out pretty quickly.

And does the space the No REZ occupies have to be considered in order to attain the final volume?

It really doesn't take up space it gives you a little space just like adding more damping material.

[Wind Chaser]

Cool and thanks.  I'll stick with a deeper 0.45 cubic foot box, made with 1" MDF and well braced.