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Preamps & gain

Discussion in 'Preamps & Processing' started by halfcircle, Nov 24, 2006.

  1. halfcircle

    halfcircle Guest

    I use a Zoom MRS802 multitrack which I simply plug my Mic (Rode NT1a) and guitars straight into. The zoom has phantom power for the mic and a dedicated High Z imput for guitars.

    What I would like to do is use an external mixer so that I don't have to keep plugging and unplugging mics and guitars from the zoom unit - it will also give me far better monitoring possibilites.

    My question is.... I assume a mixer will have a preamp for a mic and guitars, so would I need the phantom power turned on on the zoom unit? Also would the guitar signal routed through the mixer still need to go to the deicated High Z input?

    Any help greatly appreciated.
  2. Kapt.Krunch

    Kapt.Krunch Well-Known Member

    Nov 21, 2005
    If you run through a mixer connected to the Zoom, you won't want the phantom power turned on in the Zoom, but the mixer will need to supply phantom power. And, if you run your guitars through a mixer as you are doing with the Zoom, you would probably plug into the Hi-Z input of the mixer.

    If the Zoom has 2 XLR inputs, and the mixer has balanced outputs, you could simply connect, perhaps, left and right outs of the mixer into 1 and 2 inputs of the Zoom with an XLR cable, if the mixer has XLR outs, or with TRS-XLR cables (or adapters) if the mixer has only TRS outs.

    You should probably research the mixer to see what kind of outputs and monitoring capabilities it has. If you somehow end up with a mixer that has only unbalanced outputs, then simple TS instrument cables would do.

    If you want to monitor the Zoom through the mixer while you are feeding a signal through the mixer to the Zoom, you may need to find a mixer or a wiring scheme that will allow some capability to separate the monitored signal from the Zoom from the signal you are feeding to it...if the signal is being mixed through the Zoom and back to the mixer with the rest of the tracks. Otherwise, you will be putting the signal through an endless loop, and it will get ugly fast. If you were to plug in the instrument straight to the Zoom, and only monitored that from the mixer with the rest of the tracks out of the Zoom, that wouldn't be a problem...but then you wouldn't need a mixer.

    A mixer should add functionality and versatility to your setup, but the quality of the mixer should be a consideration. A mixer can add EQ and inserted effects if desired, but a mixer with bad-sounding preamps may make a recording sound worse than plugging straight into the Zoom. A mixer would also allow you to possibly record more than two signals at once by submixing down to one or two channels, if desired.

    Perhaps research what kind of signal routing capabilities a prospective mixer has, and see if you can find a scheme that will work for you. You may even find a patchbay may come in handy to, at first, complicate things, but in the end make things easier. Probably best to start off with the mixer, though.

    I'm sure there are more considerations. You can do what you want to do, and there are many ways to do it. It kind of depends on the way you want to work.

    As always, I'm just throwing stuff at the wall....some of it might bounce off. You'll probably get more detailed tips from others.

    Good luck,

  3. dementedchord

    dementedchord Well-Known Member

    May 11, 2006
    i could be wrong here but i suspect the zoom hi-z input is dedicated guitar input and NOT garden variety line level input and most likely will sound like $*^t when driven by a mixer....YMMV
  4. Kapt.Krunch

    Kapt.Krunch Well-Known Member

    Nov 21, 2005
    I wasn't completely sure either by searching the model and looking at ads. So, I downloaded the 172 page manual to see. Apparently, the "dedicated guitar/bass input" is shared by the Input 1 XLR. Use one or the other, but not both. So that does give him 2 XLR Lo-Z inputs which he can use in that way. Actually, if it HADN'T been done that way, it would have made that unit pretty much useless for any kind of stereo recording.

    That being the case, I can see why he wants to do what he wishes. Something I didn't mention before is that he could just use a simple (but good sounding) mixer, run its outputs to the Zoom inputs, and monitor directly from the Zoom, as he probably is doing now, anyway. There may be some limitations that he's trying to overcome with that also, though. At least it would open up some options. He still may consider a patchbay, also. He may want to eventually route his Rode mic through an outboard preamp, then directly to the Zoom from that. He could simply plug the preamp out interrupting, say, mixer out to Zoom input 1, and going directly to Zoom input 1. This would give him the option of using the mixer, or going direct. A 48-point patchbay may be a bit of overkill at this point, but I'm sure we all know that everyone always figures out more ways to use one, and it will be there when he needs it.

    It's pretty much how he wants to work now, but keeping an eye toward expansion, I guess. And to reiterate his first two questions:
    1) No Zoom phantom power if connecting mixer outs to Zoom XLR 1 & 2.
    2) You don't need to use the Zoom "dedicated guitar/bass input" at all if running through a mixer. Of course, the mixer won't have guitar-oriented effects that the Zoom may have? A patchbay connection MAY allow you to use one or the other. That depends on whether the Zoom guitar input automatically switches when plugged in, or if it's switchable by a switch. (Look in the manual...I already closed it). If it's switchable by front/top/back panel switch, you may be able to leave a cord plugged into a patchbay, and have easy access to it. Perhaps, it needs to go through that input to have access to certain guitar-oriented effects, or will it still do it through the XLRs? I don't know. If it automatically switches out the XLR when plugging into guitar input, you can't just leave it plugged in and use the XLR. A physical switch would be most handy, and give you more options.

    One other thing. The Zoom guitar input may be better to run a guitar directly to than a mixer Hi-Z input. It was designed specifically for that, and would probably be more suited than the mixer, which may load down a guitar, even in the Hi-Z inputs. The input may need to be turned up so much that an unacceptable amount of noise is present. May be that boosting the signal before the mixer, a direct box...whatever...is needed for the mixer to run the guitar through it. Hopefully, the Zoom input 1 has a physical switch.

    Again, just seeing if anything at all sticks. If anything is wrong, I'm glad to educated. :shock:

  5. moonbaby

    moonbaby Mmmmmm Moderator

    Feb 23, 2005
    You have to be careful using the Zoom's XLR inputs with a source different than a mic's. Those inputs are designed to be used with the very weak signal of a microphone, condenser or dynamic. Plugging the line output of a mixer into one of those mic inputs will overload the inputs and sound like crap. When researching a mixer for this application, be sure to find one that allows you to switch its' XLR outputs from "line level" (+4dBm) down to "mic level" (-50dBm). This will allow you to safely feed a pair of mic inputs on the Zoom. As far as mixer that let you do that, I know that the Mackie 1202VLZ offers this feature. This is a great selection for your scenario. Your problem will also be that the guitar plugged directly into any mixer's 1/4" line input will not cut it in that the sensitivity and frequency response of the Zooms' Guitar Input is designed for a guitar pickup, not line level. The line inputs the mixer has will just sound too...."flat" and "blah" come to mind.
  6. Kapt.Krunch

    Kapt.Krunch Well-Known Member

    Nov 21, 2005
    Moonbaby does have a good point about feeding a mixer out to the Zoom in. Yet another thing that escaped me, but now I know. I browsed through the Zoom manual to have more of an idea how this thing is set up.
    It could get messy awful fast, especially if you are using the main outs of a mixer. You could be putting a signal through a LOT of stages. Input, channel, and master of the mixer, then input and record level of the Zoom to record, and then the channel and master stages for the output...which is through RCA jacks on the Zoom. You may be able to bypass some of the stages in the mixer by going direct out, etc., but then you'd have to figure out pre-eq and/or fader, or post EQ/and or fader. If everything was pre-, you wouldn't be using the EQ or channel sections of the mixer, which may be less noisy. But a good signal for the mixer may be too hot for the Zoom. You could turn the Zoom inputs way down, but that may not be the best. Of course, you could run it though the the channel and/or master faders, which adds more circuitry, and it gets more complicated to balance everything out. This could go around in circles with how it's best to run though. And all you may be accomplishing with that anyway is putting more potential sources of noise in the path.

    Looking at the Zoom manual, they didn't make it easy to do what you want. It states that it has "XLR/Standard Phone Combo Jacks" for balanced/unbalanced input. I gather that means the 1/4" input is unbalanced, or it could possibly work with TS or TRS and automatically balance/unbalance the input, though that isn't what it reads like.

    The inputs are "continuously adjustable from -50dBm to +4dBm" which may give you room to accept a lot of varied signal levels, but you will still be running at least a mixer pre-, and possibly other gain stages, if you use a mixer. If whatever signal coming from the mixer is very hot, then you'll have to lower the input level on the Zoom, and if it has to be too low, it may cause problems. Whether it makes much of a difference to run anything through the XLR or 1/4" of the input, I don't know.

    The other problem is one that Moonbaby and I brought up already. According to the manual, the guitar/bass input DOES automatically take priority over Input 1 on the Zoom, when something is plugged into it. So there is no way you can keep anything permanently plugged into that, if you wish to use Input 1 for anything else. And plugging a guitar into a mixer without help is usually not the best.

    It appears no matter what you do, you will have to still do some amount of patching things around, and you may end up with worse sound. It seems those things are not really designed to do much more than they can do. You CAN run a mixer into it, but you'd have to be very careful about levels, and all the stages a signal has to go through may be noisy and more trouble than it's worth. Then again, if you get what Moonbaby suggested, and permanently connect, say, a Mackie to it and try to get decent levels, then you could use a mixer for that, and simply plug a guitar into the back of the Zoom when you want to use the guitar input which will automatically disconnect the Channel 1 XLR/1/4".

    Then there is still the routing questions and capabilities of the mixer if you want to use the mixer for both recording through and monitoring the Zoom. About all you can do is get a mixer and see if it works for you, or continue doing what you are doing.

    Just some more things to ponder and generate more ideas or corrections. :wink:


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