Mackie Pro FX12 - Mixer "Hybrid" input???

Started by Smokey5159, June 14, 2015, 03:31:43 PM

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Smokey5159

Hi guys,

Just a query on the Mackie Pro FX12 I've just bought...
Can anyone who has a similar mixer share their understanding on the "hybrid" input?  The input is set to Unity gain, and there is no gain control on that (line in) input - only the corresponding Mic input.
I note that in their example diagram, that they suggest using them for electric guitar and bass inputs that have effects units in-line. Would that suggest that the (mixer) on-board pre-amp is not used because that leaves room for the effects own preamp - and that the likes of the GR55's output would be uncoloured and simply pass through, but also have the benefit of the Mixer on-board EQ, should you desire to use it?
I haven't received the mixer yet (hopefully today, or tomorrow) so until then, I won't be able to try different inputs. It's just an interesting set-up that I haven't seen before.
I would like to hear from anyone who has a similar mixer option, and if there is much benefit in using the inputs as Mackie have suggested...
Cheers, Smokey.

Mrchevy

Do you mean the "Hi-Z" button? This copied from an article I found in RECORDING REVIEW should explain...

"Line Level refers to the type of signal that mixers, audio interfaces, etc use to pass audio signals back and forth. Microphones do not output line level signals so we use a preamp to boost this signal up to standard line level so we can manipulate the audio as we wish.

Hi-Z stands for high impedance. Without getting overly technical, every electronics thingy has an input and output impedance. The ratio between the output impedance and the input impedance has a dramatic effect on the amount of level sent. A real world example of this is with microphones. All microphones have an output impedance of some kind. Of course, the microphone is plugged into a preamp which has an input impedance. The lower the output impedance of the microphone and the higher the input impedance of the preamp, the more signal is passed into the preamp.

For the most part, this really isn't all that important for recording music. It may come up here or there, but most of the electronics mumbo jumbo has been taken care of for you so you can focus on music. However, there is something you should be aware of. The lower the output impedance and the higher the input impedance, the more aggressive in the mids and highs the signal is going to tend to be. This is due to inductive and capacitive reactance. You certainly don't need to understand capacitive reactance to be a killer recording dude/chick, but if you are interested you can look into this more.

Inductive and capacitive reactance is the reason that long guitar cables suck tone. The longer the cable, the greater the apparent output impedance of the guitar, the lower the ratio between input and output impedance, and therefore the duller the signal tends to be..

Real World Application

For people recording direct guitars (I've got that sick feeling in my stomach like I've just watched a "Feed the Children" commercial), line level is not ideal. This is because of the relatively high output impedance of electric guitars. They just don't mate well with plugging straight into preamps. Guitar amps and pedals generally have much greater input impedances than mixers and preamps do. So, Hi-Z inputs started showing up on audio interfaces, preamps, etc. The idea is to give the guitar a load that it's used to seeing (and therefore make it sound the way you are used to hearing it).

Of course, I hate just about everything about direct guitars, so take that for what it's worth. If your direct guitars are coming out muffled (as opposed to the usual mega mega mega fizz you hear on many Myspace guitar tones), you may look into getting an audio interface or preamp with a Hi-Z input. Of course, I still think you would be better (when possible) to use a real amp and a microphones.


Impedance, Microphones, and Preamps

Different mics sometimes have very different output impedances. Different preamps have very different input impedances. Because of that, a SM 57 plugged into preamp A vs preamp B may sound quite a bit different. But a condenser microphone may sound pretty much the same when plugged into preamp A or preamp B. This is because of the different input and output impedances.

Some high end preamps will have selectors so that you can change the input impedance. This can often make quite a difference in the tone."
Gibson Les Paul Custom
Epi Les Paul Standard
Gibson SG 50's prototype
Squire classic vibe 60's
Epi LP Modern
Epi SG Custom
Martin acoustic

Princeton chorus 210

GT100
GR-55
Helix LT
Waza Air Headphones
Boomerang III

And, a lot of stuff I DON'T need

Mrchevy

Opps, sorry, they do mention HYBRID in the manual, but I'll leave previous post up for reference. I think all that means is you have the option  of using those 2 channels  for mics, balanced, stereo, or mono. The gain control only affects the mic input on any given channel though. This just from skimming the manual real quick. But now the wife is calling so I gotta go. Damn thats a nice board, you sure it's not to much for you. My offer still stands ;)
Gibson Les Paul Custom
Epi Les Paul Standard
Gibson SG 50's prototype
Squire classic vibe 60's
Epi LP Modern
Epi SG Custom
Martin acoustic

Princeton chorus 210

GT100
GR-55
Helix LT
Waza Air Headphones
Boomerang III

And, a lot of stuff I DON'T need

Smokey5159

Hi again Mrchevy,
Thanks for the kind offer - but I couldn't possibly put you through too much angst..! :)

That article is very informative, but I'm not really sure the Hi-Z is meant for the output of an effects unit, but maybe an acoustic guitar.

What I guess I'm asking is - do I use the mixer's on-board preamp (gain control) input, or do I use what they suggest - the hybrid, where I think the on-board mixer preamp is bypassed.
The GR55 has it's own preamp - so being the novice that I am, I take that to mean you shouldn't then enter the output into another preamp, then to the main mixer out..?

I'm mainly interested why Mackie would suggest the output of guitar effects pedals be put into these "hybrid" gainless inputs, and not into the other mic/line inputs - or even into the Hi-Z...

Also, what is the best input scenario for our gr55'S that use powered mixers in terms of preamps etc - that give us the best uncoloured output from the GR 55..?
Cheers!

Mrchevy

In the diagram, the guitar effects are being used as mono, but you can run them stereo into the same channel, just use a TS 1/4" L/R at the L/R inputs,  L/R 1/4" jacks from the GR55 for example. It doesn't really matter which inputs you use. If you are running a mono signal into the board, use 1,2,3,or4, if you want to run stereo, use ch1/L- ch2/R, ch3/L- ch4/R, 5/6, 7/8, 9/10, 11/12, inputs and use the L and R 1/4" inputs with mono L/R cables. When using the 1/4" cables, the gain controls on any given channel are irrelevant because they only affect the XLR inputs. If you plug a mic into those channels, that is when you use the gain level. In a different example, My Mustang Floor MFX pedal also has XLR outputs along with 1/4" outputs. If I choose to use the XLR outputs to the boards XLR inputs, then I would just turn the gain down as it is a line level signal and does not need gain boost. The one channel with the Hi-Z switch is for running a guitar direct that has either passive pickups, or an acoustic that does not have a preamp on board. Otherwise ch1 is left with the Hi-Z switch off and used as a standard line level mono input. In the first pages of the manual, it talks about zeroing out your board, this is the process of getting your levels and unity gains (optimal signal to noise ratio) set up.
Gibson Les Paul Custom
Epi Les Paul Standard
Gibson SG 50's prototype
Squire classic vibe 60's
Epi LP Modern
Epi SG Custom
Martin acoustic

Princeton chorus 210

GT100
GR-55
Helix LT
Waza Air Headphones
Boomerang III

And, a lot of stuff I DON'T need

beggar

dear all   i wonder why on the hybrid or stereo input channels of the mackie  if i plug in a microphone  i will get a lot of noise /buzz out of the  output speakers  is that b/c  those channels have preamps?  if so how could i disengage the preamps and still use those channels for microphones ??     thank you


beggar

thank you  very much  except mackie s tech person thinks there is something wrong  but i am not too sure as the first 4 channels   (mic channels) all work well  n then when i test the hybrid and stereo channels  i get the buzz     

BackDAWman

If that's the model with the onboard graphic EQ try switching it out. Mine had a terrible buzz and hum when using the EQ but fine without. Unfortunately the warranty ran out before I found out it was a problem...