So, ye who understand audio science. . .

Zoa · #1 11-03-2010, 02:59 PM

My band has an outdoor gig coming up in three weeks. There is no amplification provided, so we will have to use our own incredibly crappy PA. It is, don't laugh, a 1971 Kustom k150 with two speaker columns. No monitors. Only the vocals will be going through this, everyone else will use their own amps. This is less of a problem than it would be for many bands, as our guitarist is perfectly happy playing ridiculous solos at a volume that could be drowned out by an un-miked lap dulcimer. He is the only guitarist that I have ever had to tell to turn up.

Anyway, we are playing in a tight space, with a four-foot stone wall behind us. the drummer is going to have to be close up against the wall. I signal a lot of the transitions, so it is pretty important that he be able to hear me, and it is going to be impossible to get my rig behind him.

I am playing through a acoustic b200h with two 15s. My question is this:

what would happen if I put one of the 15's on the stone wall directly behind the drummer, and one seven or eight feet to the left, still on the wall, behind me? Would this cause major difficulties with comb filtering, phase, etc? Or should I rig up one of my smaller combos (crate b50, behringer 180) to serve as a monitor? Would this cause difficulties as well?

It would be helpful to know, as we are probably going to be playing here a lot.
Muchas gracias!

rpsands · #2 11-03-2010, 03:02 PM

You would get low end cancellations and sound like crap.

You should put all your LF sources in one area. What I would try is stacking the two cabs so that one is aimed at the audience and one is 90 degrees to face the drummer.

billfitzmaurice · #3 11-03-2010, 03:05 PM

Quote:

Originally Posted by Zoa

Would this cause major difficulties with comb filtering, phase, etc? !

It would. You need to place your cabs close to the wall, for boundary reinforcement. Put the 15s one atop the other. Aim the lower cab at the drummer so he can hear your mids, aim the top cab at you so you can hear them.

Quote:

we are probably going to be playing here a lot.

Invest the proceeds in a good PA.

Zoa · #4 11-03-2010, 03:13 PM

Quote:

Originally Posted by billfitzmaurice

Invest the proceeds in a good PA.

Got $300 in the chest already. . .more to come.

The stone wall encloses us on three sides. Would pointing one of the cabs at the drummer (and thus at the wall) create issues with sound bouncing off the wall and muddying things up?

Thanks again!

agreatheight · #5 11-03-2010, 03:16 PM

If you put the speakers so that the business end of a microphone is pointed at it, you are gonna have worse problems than comb filtering. Feedback, anyone?

Zoa · #6 11-03-2010, 03:18 PM

Quote:

Originally Posted by agreatheight

If you put the speakers so that the business end of a microphone is pointed at it, you are gonna have worse problems than comb filtering. Feedback, anyone?

Yep! that I know how to deal with.

rpsands · #7 11-03-2010, 03:29 PM

I doubt there would be any serious feedback issues with the volume level we're talking about. And hypercardioid/cardioid patterns of most good stage mics make it pretty easy to achieve a decent stage volume without feedback. At least, this has been my experience.

I would not worry too hard about the midrange reflections. You'll have to dial it with EQ probably but if it was really bad (e.g. caused boundary cancellations or something) you could adjust the position of the cabinet to counteract it.

None of that is super scientific, just been my experience in small areas.

Zoa · #8 11-03-2010, 03:31 PM

Thanks very much! I appreciate it!

Johnny Crab · #9 11-03-2010, 04:09 PM

If you are directly next to your drummer(as I am and have been for decades) AND your cabinets are not rear-ported you may want to put them at an angle to the wall(15~45 degrees) depending on where they are pointed audience-wise(you didn't say how big the front area is). This will reinforce low end and provide for drummer needs. I 've been where you are but it was with a 15 on the bottom and a 4x10 on top. Against the wall and tilted ended the "I can't hear you" chant.

2 cents.

tappingtrance · #10 11-03-2010, 04:23 PM

All good advice above - keep your rig together (amazing how thin your sound becomes outdoors) and if the drums are not miked you do not have a lot to worry about.