Something is wrong with my Modula MTMs

[JoshK]

OK, so I hate to admit it, but I somehow goofed something up with the Modula's when I upgraded them with Theta's. Currently I have no bass (not that I expect a lot) and no midbass.

I didn't have time to really investigate or setup my mike, but I busted out my Rives test disc and listened. Basically it is dropping off sharply below 315hz, 125hz isn't even audible. Any idea what could cause this?

I didn't stuff too much, maybe about half the volume. The port is the appropriate length and there are no leaks in the box that are obvious. I put my ear near to the port when playing music ~75db (guessing) and there was no air movement or sound that I could hear.

I won't really have time to play with investigating them for a few days and just thought I'd ask if anyone has a guess to what might be up.

[Paul H]

You may have your mids wired out of phase with each other.

Paul

[Mazeroth]

You may have your mids wired out of phase with each other.

Paul

B-I-N-G-O

And Bingo was his name-o!

:B

I hope that fixes it. Keep us posted.

[JoshK]

That was my first thought, but somehow I managed to confuse myself into thinking it couldn't be that. Will take a look. It makes sense when you consider that the two drivers will null the pressure in the cabinet out....which is why there is no port air.

[cotdt]

unrelated to your problem, but have you tried less stuffing? in my experience, using heavy stuffing in ported designs makes them sound like and measure a lot closer to sealed than ported, and this can either be good or bad depending on whether you prefer sealed or ported. i wonder if you will find the same experience.

[JonMarsh]

My money is on out of phase midwoofers, too. Most common mess-up with an MTM. It's hard to imagine anything else that would produce the symptoms you describe, Josh.

~Jon

[JoshK]

sho'nuff!

I pulled the drivers out and I had the upper one backwards on both sides. Fixed it, plugged them back in and voila, back to normal.