Solution to comb filtering?

No. The problem is caused by the physical distance between the cabs. The cure is to limit that distance to less than 1/4 wavelength or increase it to at least 2 wavelengths. In the 40 to 100 Hz bandwith that equates to either less than 2.8 feet or more than 56 feet.

 

There's an extensive thread about this.
http://www.talkbass.com/forum/showthread.php?t=389159&highlight=vertical

 

biamp, and eq them slightly differently, will help alil, but that prolly aint the sound your going for, btw, nice choice on the 2x15s I thought I was the only one who still used those, you have the fender ones? I got one swr, that I also run with a bassman, and then with 410s and a 18,. so i got to ask just how many shows do you get to break out both cabs? cuz I almost never get to, and Im in 3 piece

 

OK, here's a topic I just learned the basics about...beaming. Do I have it correct that even if you turn the cab vertical, a 215 cab will react as a driver the size of both put together and greatly increase beaming to where the highs will only be heard directly in front of the cab?

 

KJung,
I wonder if Nick or Jim employ a special circuit in their designs so that it's low passed on one side and full range on the other. It doesn't seem as though I hear about anyone mentioning comb filtering in regards to Epifani or Bergantino cabinets.

 

I know that's not the case. I again do believe this effect is real, and has a minor impact of sound dispersion just like the placement of the cab, the room itself, etc. I've just heard too many side by side stacks or 410's that sound just beautiful and even out in the room and on stage, and also plenty of vertical stacks that sound 'beamy' and like dog. I hear a zero correlation, again, WITH THE BASS GUITAR. I'm sure more program type audio with full, wide frequency response (CD's, etc.) would be impacted more meaningfully.

I wonder if, assuming the OP is actually hearing some problem and not just reacting to an article or something, the 'problem' really is due to 'comb filtering'.

I guess a simple way to tell this would be to just unplug one of the cabs for a song, and see if the dispersion and tone magically become much better

 

I don't think it's any special wiring in those cabs. I think it's that some people are bothered by it more than others. Me, I can live with some minor comb filtering coming from a bass cab or cab stack like a 410 or 810. I can't live with it from cabs set up side by side, though.

I'll tell you what, though...last night on my gig, I was incredibly bothered by comb filtering in the PA. Small room, soundman had subs on both sides of the stage. Bass response varied wildly in the room. In some places it was great. In some places it was almost completely gone. Not only comb filtering from the PA, but the walls were extremely reflective, which certainly didn't help.

 

No. It will act like a 34" driver if you lay it down horizontally. But even a vertical 2x15 will beam at fairly low frequencies, that's the nature of large drivers. You don't want beaming? Add a 6 inch mid.

No one is immune to the laws of physics. Most players are totally unaware of the effects of combing as they don't stand in various locations throughout the audience where its effect is obvious. Tone also enters the equation. If you roll off your response above 1kHz there's nothing to comb. Combing would never have bothered Jamerson. It should have been an anathema to Entwhistle, and had he known of its effect on his sound he never would have used the rigs that he did.

The way I read his question he's referring to cabs split to either side of the stage, which not only makes combing more obvious than with cabs placed side by side but also extends the frequency range where the combing occurs downward by octaves. Splitting cabs, just like placing PA subs on either side, is usually done because intuition says doing so will increase dispersion. The reverse is the case.

 

Ah... I misread the original post. That makes sense.

 

Well, for bass, I'm not all that concerned about beaming. I just stick a mic in the center of the driver, and the lack of highs elsewhere onstage is the other guys' problem But I have been toying with the idea of putting together a PA, so I'm trying to get up to speed with the beaming. Thx Bill!