micing a cab w/ woofer and midrange? (15/6)

nodestiny · #1 06-14-2009, 12:45 PM

I have not had a chance to really test it myself, but whats a good starting place? I have a 15/6 DIY cab that sounds amazing at any angle, but not sure how to go about using a single mic on it to capture the most sound, yet not too far back to capture any other noise.

Any suggestions on where to start?

JimmyM · #2 06-14-2009, 01:29 PM

I'm very interested in this as well...I've never miced a 2-way cab with a mid driver, but I may be getting one soon for a beta test of a new cab. With a tweeter, it's no problem because tweeters almost always get picked up by a mic, but I don't know how a mid driver will do. I'd hate to run two mics with it because I am lazy

Nick Kay · #3 06-14-2009, 02:18 PM

My first instinct would be to use two mics, but if it's a one-mic solution that you need, I see two possibilities. A hypercardiod set 6 inches to a foot off the grille and pointed at the baffle between the mid driver and the woofer SHOULD pick up both drivers fine, although you won't be getting an on-axis type of sound with either of them. It should also reject most ambient sounds, but we're almost relying on the fact that shotgun mics aren't perfect. You could also use a regular cardioid a bit closer to the grille.

The other possibility is to use a cardioid pattern close to the woofer or the mid driver, but point it towards the other driver. You might get some phase coherency issues that are difficult to correct, and that big patch of pickup pattern that isn't closed off by the cab could cause some bleed issues, but it's doable.

Honestly, though, I would just DI and throw filters on to simulate the roll-offs of the cab. Most of those modern PA-style cabs come close to flat response, so the difference between miking and DI in the FOH mix would be negligible.

link wray · #4 06-14-2009, 03:01 PM

Since deep bass is omnidirectional i'd choose the 6 inch driver if there was only 1 mike.

Nick Kay · #5 06-14-2009, 03:21 PM

Quote:

Originally Posted by link wray

Since deep bass is omnidirectional i'd choose the 6 inch driver if there was only 1 mike.

That's only true of DEEP bass with most cabinets. Sub 100Hz, for the most part. The wavelength of the frequency must be significantly larger than the dimensions of the cabinet for the frequency to be omnidirectional. In the case of the average mid driver crossed over at, say, 600Hz, you've got a huge hole in your response between 100Hz and 600Hz if you only mic the mid driver.

sonic assassin · #6 06-14-2009, 03:33 PM

does the cab have a crossover?

if not, then decide which speaker reproduces the biggest part of the sound you need sent to FOH.

some guys talk of running a DI AND a mic, why not 2 mics? not enough room on the board? perhaps get your own small mixer and send one blended signal to the board.

link wray · #7 06-14-2009, 05:40 PM

Quote:

Originally Posted by Nick Kay

That's only true of DEEP bass with most cabinets. Sub 100Hz, for the most part. The wavelength of the frequency must be significantly larger than the dimensions of the cabinet for the frequency to be omnidirectional. In the case of the average mid driver crossed over at, say, 600Hz, you've got a huge hole in your response between 100Hz and 600Hz if you only mic the mid driver.

omnidirectional would be 360 degrees. For the situation as described 180 degrees would do. My guess is that would be around 400 hertz.

nodestiny · #8 06-14-2009, 07:59 PM

for my setup, yes, its Xover'd @ 650Hz each way between mid and woofer.

Nick Kay · #9 06-15-2009, 05:05 AM

Quote:

Originally Posted by link wray

omnidirectional would be 360 degrees. For the situation as described 180 degrees would do. My guess is that would be around 400 hertz.

Assuming that was correct, you'd still have a pretty bad hole between 400Hz-600Hz. Unfortunately, 15" drivers start beaming at around 250Hz, and are pretty much shotguns at 1K. With bad enough mic placement (ie: cardioid close on the mid driver pointed away from the woofer), the hole can start as low as 100Hz and go all the way up to the crossover frequency. With some careful handling, you could reduce the hole to 500Hz-600Hz, but you'll need to pull the mic further back and get it within a 90 degree arc of the speaker's dust cap.

Or, you could just move the mic so it's between the two drivers and reasonable on axis for both, and not have to worry about a frequency hole. Better yet, halve the centre-to-centre distance of the drivers and plunk the mic straight in the middle. Or, put the mic by the woofer and point it at the mid driver. Or any other of a variety of solutions that account for both drivers easily.

greenboy · #10 06-15-2009, 10:56 AM

I'm pretty much with Nick here on single-micing technique, though I'd say that the 15 beams more above 500 Hz.

With a 6ND410 for the midrange padded back to match 3015LF sensitivity I would just go DI - post effects if they are being used. But with the Alpha6 I'd consider micing because it's probably not at parity even with baffle step taken into consideration. That's not a highly voiced cab up to its cutoff frequency, but it is voiced enough to consider micing.

As always, experiment though.

Greyvagabond · #11 06-19-2009, 04:02 PM

Since the idea of a 15" and 6" is to get a great uncolored sound, would it make sense to just run a DI? Let the cab be your monitor. Otherwise, its kinda silly

GregShadoan · #12 06-19-2009, 05:54 PM

DI to start with definitly. When I mic a bass rig with a 15, and a 4x10 I will always mic one of the tens. So given that logic, I would DI, and mic the mid speaker. I have never done it with that paticular configuration, and would be an interesting experiment to try. Hopefully I would have enough time to test the two configurations, ie. the 15" -vs- the 6", and a DI combo, to find the sweet spot. IMO there is nothing coming out the low end section of a two way bass rig that I can not get with a DI.
Greenboy should try the experiment and report back to us, on his design. See what sounds best. DI and either speaker one at a time.

JimmyM · #13 06-19-2009, 06:14 PM

I think these are all legit approaches, and it looks like if I'm going to have my cake and eat it too, DI + mic on the mid driver would probably be my best bet.

But (there's always a but) I don't see where uncolored tone and micing have to be mutually exclusive. I don't mic because I'm trying to get a colored tone, although I do confess to liking a slight bump at 125-200 hz. I mic because I like the sound of the air from a bass cab hitting the diaphragm of a mic and making a pleasing tone to my ears. If you mic a flat respnse cab with a flat response mic, it's going to come out of the PA or out of the recording monitors as flat. It's just that little extra aggression that DI's are notorious for not having that I'm going for.

greenboy · #14 06-19-2009, 07:32 PM

If you've got decent board EQ or dedicate insert EQ it's often easy to blend DI using the EQ of it as an ersatz lowpass, and use the mic channel's EQ as a fake highpass. While not perfect, it'll get rid of a lot of phase issues and also give some air/acoustical detail. But in the case of the 15/6 there's a little info to be had off the woofer that's valuable on the mic side if you go this route.

Myself, I just wanted a cab that was more like a good PA in reponse, and had better off-axis even power response for stage mixes on smaller stages. When playing with good PA support I send an identical post-EQ post effects signal to both my amp and enclosure, and FOH. My preamp EQ emphasizes what I want heard, and that is what the FOH send also has... No bad surprises, nothing that needs compensation, and if I roll off lows to deal with placement/wavelength subwoofer issues, it can be had right back in inverse at the board since it is a general shelf like most mixers have for their lowest knob.

But nodestiny does not have parity output between midrange cone and woofer, making it a more voiced enclosure in the sense that it's not so closely resembling a good PA stack. So there miking could make some sense. I've mic'd two-ways before and found that one mic could do the trick if baffle arrangement of drivers was not bollixed. A minute with a flatter mic, positioning to avoid null or lobe at crossover frequencies (ear tells all here) should get it just fine.

Combined with DI with some version of what I described at the start of the post should be fine too.

JimmyM · #15 06-19-2009, 09:29 PM

Good tips, Greenie...thx. I guess it just requires a combination of seeing what the cab cab do by itself and playing around with it.

Greyvagabond · #16 06-22-2009, 09:22 AM

My point about mic'ing an "uncolored" cab is more of a practical one, in the sense that a lot of sound guys whine about mic'ing the bass cab in the first place. For me, going through that hassle only makes sense if my bass sound through my amp is significantly different from just a DI. To my ears, a good "uncolored" cab ideally sounds exactly like DI'ing your bass through a high-quality board and PA system, so the added work of mic'ing (not to mention potential stage bleed and feedback issues) isn't worth it. But I don't have the best ears, so probably can't hear the different between a mic'ed "uncolored" cab and a DI

greenboy · #17 06-22-2009, 01:57 PM

Quote:

Originally Posted by Greyvagabond

My point about mic'ing an "uncolored" cab is more of a practical one, in the sense that a lot of sound guys whine about mic'ing the bass cab in the first place. For me, going through that hassle only makes sense if my bass sound through my amp is significantly different from just a DI. To my ears, a good "uncolored" cab ideally sounds exactly like DI'ing your bass through a high-quality board and PA system, so the added work of mic'ing (not to mention potential stage bleed and feedback issues) isn't worth it. But I don't have the best ears, so probably can't hear the different between a mic'ed "uncolored" cab and a DI

We are on essentially the same page; my only distinction is that some 15/6 cabs are not using a midrange driver that is at the same adjusted sensitivity as the woofer. Even then, if the crossover isn't poor they can be pretty nice targets for DI-only use.