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Micing the Back of a Cab?

Posted: Tue Jul 13, 2010 9:33 pm
by Sam_from_Texas
So, I bought the open back Avatar 2x12 because I like open backs a lot more than closed (just more pleasing to my ear). But, I was wondering if to get the full effect of that sound in a gig if I should be micing the front AND the back? Or does it not matter at gig levels and I just should throw a mic in front and not worry about it?

Gigs : Church stuff, smaller venues (if it matters)

Re: Micing the Back of a Cab?

Posted: Tue Jul 13, 2010 9:49 pm
by Thinline_slim
My response is completely unfounded and purely opinion based on most of the things I've read...on the internet.

Have you actually miced the back of the cab and listened to the playback? If so, and that really is the sound you like then I would say have at it, otherwise....

First off, micing both the front and the back of the cabinet is a very common studio practice and there is a difference between the sounds that you will get between the two. There could be some phase issues with that technique though, not sure.

Some cabinet makers have claimed that where the "open" back part of the cabinet is located will affect the frequencies that actually come out of the back. i.e. if it's open in the middle you will get more of the speaker mids to come out. I have no idea whether that's accurate or not.

Another thing to consider is, by my logic, micing the back of the cab is catching the reverse throw of the speaker, like if you wired the speaker out of phase from the beginning (Lots of info on that out there) which I think you would loose a little bit of your attack and punch by only micing the back.

Bottom line, record it and see what you think. Your ears will pickup a ton of information in the room while playing that the mic won't so if you've found your preference is listening to the back of your cab while you play, the mic will pick up much less of what the front side of the speaker is doing in the room.

Just my 2 cents

Re: Micing the Back of a Cab?

Posted: Tue Jul 13, 2010 10:02 pm
by Sam_from_Texas
Wow Jake. Quite an answer. Thanks a lot. I'll definitely look into the points you brought up next time I mic up.

Re: Micing the Back of a Cab?

Posted: Tue Jul 13, 2010 10:05 pm
by irish_admiral
Agree with much of the above.

In practice, miking the front of it will be just fine. You'll still get a bit of the effect of the cab from the noise it generates off its own back, and the rest of it - usually close miked on one of the speaker cones - will feed into the FOH mix to support your sound.

If you've got plenty of time and a friendly sound man, just have a few hours moving the mic around and seeing how it sounds. You can tweak your setup from there. But to be honest I wouldn't worry about it much. No one else will hear much difference, and you can still get a great sound miking up the front of the amp.

Re: Micing the Back of a Cab?

Posted: Tue Jul 13, 2010 10:25 pm
by bclaire
Some guys will mic the back of a closed back 4x12 in the studio to get that whomp...

Re: Micing the Back of a Cab?

Posted: Wed Jul 14, 2010 4:10 am
by CD9266
I agree with what Jake said. Bottom line is, your ears pick up the room, the mic does not. It picks up the direct sound coming from the amp (assuming you are close mic'ing). Try it, if you like it, then great. It might not have the best sound that your listeners will like for an all the time thing, but you might be able to find a use for it for certain songs or whatnot.

On that note... any sound can find a use. My friends have a song that I kid you not starts out with a weird hum sound like if you touch the end of your cable lead while it's plugged into the amp and it buzzes and hums...

Re: Micing the Back of a Cab?

Posted: Wed Jul 14, 2010 4:40 am
by Sam_from_Texas
I'll have to check it out. Hey quick ?: I have a v30 and a G12h30, but I'm having a hard time figuring out which one to mic up to cut through the mix better. I haven't had a chance to check it out through a PA yet, but I don't always have a lot of time for sound checks and it'd be nice to know if I should stick to one or the other (at least for live stuff).

Re: Micing the Back of a Cab?

Posted: Wed Jul 14, 2010 4:58 am
by baytamusic
Sam_from_Texas wrote:I'll have to check it out. Hey quick ?: I have a v30 and a G12h30, but I'm having a hard time figuring out which one to mic up to cut through the mix better. I haven't had a chance to check it out through a PA yet, but I don't always have a lot of time for sound checks and it'd be nice to know if I should stick to one or the other (at least for live stuff).
My opinion is mic the one you like the sound of better. If the sound guy is worth anything he'll take care of the getting the mix working out front no matter which speaker you use.

Re: Micing the Back of a Cab?

Posted: Wed Jul 14, 2010 3:54 pm
by Borderline Productions
I don't see any advantage in a sound reinforcement setting of using both. Maybe in the studio you might want to use a room mic (large diaphragm condensor) for the back to get the room feel the open back cab gives. You will spend hours on mic placement and flipping the phase switch until you get the sound you want. I don't know if you will like the sound any better.

Re: Micing the Back of a Cab?

Posted: Wed Jul 14, 2010 5:15 pm
by Ohara
quick question.....When you play on stage do you turn the speaker cab around so that the back is facing you? Just cause you like the sound of an open back cab doesn't necessarilly mean you like the sound coming out of the back. You like the overall presence of sound that projects out of the front of the cab and also out of the back of the cab, which usually bounces off of the wall behind it, which is what you are actually hearing, not the sound just directly out of the back of the cab. Simple test would be to turn the cab around backwards next time you play on stage and see if you truly like "that sound" before you worry about micing it up.

Re: Micing the Back of a Cab?

Posted: Fri Jul 16, 2010 11:31 am
by blacklight_uk
Phase issues: yep, the back will have opposite polarity to the front, and of course there will almost certainly be phase differences due to the difference in arrival time at each mic. Any sound guy worth his salt will deal with that though!

In my experience most of what you pick up from the back of a cab is pretty useless - boxy low mids, very little top end - but it can give you a nice bass boost provided the above phase issues are dealt with. I've never seen it done live but that doesn't mean it won't work!

Re: Micing the Back of a Cab?

Posted: Fri Jul 16, 2010 11:39 am
by neonrust
Whatever you do DON'T mic it like this......

Image

Re: Micing the Back of a Cab?

Posted: Fri Jul 16, 2010 1:10 pm
by Randy Bass
neonrust wrote:Whatever you do DON'T mic it like this......

Image
That's the only way to pick up the plywood-filtered hum dynamics of the OT though.

I guess that guy really doesn't like his G12T-75s!

Re: Micing the Back of a Cab?

Posted: Fri Jul 16, 2010 3:07 pm
by Borderline Productions
Great picture! Do they have a hanging mic that does the same thing?

Re: Micing the Back of a Cab?

Posted: Fri Jul 16, 2010 9:09 pm
by bclaire
Image

Frank's amp, last gig.