Need help finding info on a PA Mixer:
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Posted on Jan 16, 2013 05:08 pm
J-bot
Byte-Mixer
Member Since: Dec 04, 2007
So, the drummer I'm working with has a PA Mixer: A Zebra ZM-0812 powered mixer, 8 channels, and kinda limited on the outputs. (all I could see were 1/4" main L/R out, which are each 150W @ 4ohm)
We were mucking around with it today, he's got his drum mics on 5 of the channels (snare mic, kick, and 3 tom mics which are from a CAD drum mic kit) Overheads are on a small 8ch (4 mic) behringer mixer, since they need phantom power. (he's got a pair of pencil condenser mics)
I couldn't see any other outputs on the PA mixer, just the Mains on the back, and some tape in, aux in on the front, a single send and a single return, and that's it.
So first we tried recording off the mains, and I got nothing but a quiet, thin, buzzy distorted signal going into the line-in on his laptop (which is a mac set to record from the line-in)
So, I switched things around to try coming through his little behringer mixer. PA Mixer Mains -> Behringer since I couldn't see any other outputs. And tried recording off both the control room out and the alts on the behri. Still got a thin buzzy signal from the PA mixer, but the overheads came through okay.
I'm thinking it's gotta be a signal routing issue on his and my part (I'm not used to working with PA mixers) so a manual would be helpful. (Either that, or the PA mixer is shot)
So, I was looking around the net trying to dig up info on this little mixer, and I can't find jack **** about it. Just some obscure vendors selling it, and a few spanish sites mentioning it :P But no manual. And some of the vendor listed specs info is incorrect.
This is the only "correct" info I can find:
www.caraudiodeals.com/zeb...812-p-1695.html
the only other vendor listed incorrect info.
At this point I don't know if the PA Mixer is just shot, or if it's user error (routing problem) or something else going on. Tried swapping cables to see if there was a problem there...etc. But no change. The only other thing I can think of, is to get it to his laptop (he has no audio interface) he's sending the stereo out into an 1/8" adapter/splitter. But....the overheads come through just fine...so that can't be it.
I know it's generally bad to record off the mains because you get the mic + the power amp noise. But I don't see any other option. Also, I'm not sure he has the budget to get a better mixer or audio interface. Maybe down the road, but not right now.
Next time I'm over there I'll take some of my stuff with me to try and trouble shoot the signal chain. But yeah, I distrust that PA mixer at this point.
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Jan 16, 2013 06:48 pm For one, you never want to run the outputs from an amplifier into anything other than a speaker or attenuator. Theres a good chance you could damage the amp or input on the mac by doing that as you're feeding it a voltage much, much higher than it is built to receive.
Does the powered mixer have a headphone output? I would say thats your best bet.
The other way you can do it is to use the send (aux/monitor) on the mixer as a mono output.
J-botByte-MixerMember
Since: Dec 04, 2007
Jan 16, 2013 07:33 pm Yep that's what i was thinking. I'll have to look at it again next time I'm over there about the headphone out. The Behri definitely has a headphone monitor, but I don't know about the Zebra.
And yeah, I think I'm gonna have to use that send to capture mono, and the overheads with the Behri to give 3 channels. That will at least give him something to work with. (assuming the signal coming off the send on that Zebra PA mixer is good)
Granted, I'm not used to working with an amped mixer. The knobs above the channels appear to be L + R / Main. But there don't appear to be volume or gain knobs. But each channel does have a monitor knob, and I'm guessing those route to the send for monitoring. So, maybe I can make a mono output work. I'll just send that to the Behri, and capture the spaced pair and the mono feed. Might at least give him something to work with.
And this is at his home for the record. I'm trying to help him learn how to use some of the equipment he has, because he's interested in getting to know the technical side of things.
Jan 25, 2013 01:23 pm Sorry I didn't see this post until now.
The reason that the sound was thin and tinny, is the fact that you were feeding it 30 volts or more to an input! In other words, clipping the living piss out of the thing! So, it never saw the full wave, as the wave was humungous! An input looks for a mic level signal, which is about a half of a volt.
You may have killed the Mac computers, and the Behringers inputs! Yikes!
On most of the powered mixers, even the aux send is tied to the power amp out. One side will become the mains, the other the Aux.
My suggestion would be leave the powered mixer out of the equation completely! Lose the thing, and find a non powered mixer to set up everything.
J-botByte-MixerMember
Since: Dec 04, 2007
Jan 25, 2013 07:51 pm Thanks Rob. The last time I talked to the guy, he mentioned trading it in to get another behringer, and I said that was a good idea.
Then he emailed me again asking which output he should use on the PA, and I told him to use the headphone out if it has one, or try the send on the front. I told him that the mains on the back should only be used with speakers, as CS pointed out above. I don't think the front send (single 1/4" jack) is amped, though I can't really be sure.
I agree, leaving the thing out entirely would be the best option. I haven't talked to him since Monday, so I don't know what he's got planned right now. I know he said he could trade it in at a local pro audio shop, and get something different. So maybe that is what he's working on getting done.
I think he said he'd e-mail me again once he got stuff sorted out. In the meantime, I'm working on other stuff that doesn't involve a powered PA mixer, hah!
Also, last I checked, the behringer and macbook both seemed to have survived, thankfully. Needless to say the situation left me quite wary of having a PA mixer in a home recording situation.
