impedance.. ohms.. help!

R

richardosim78

New member
hi ,
im into home recording, composing music, playing guitar, a bit of singing, midi stuff etc...
ive got a question:

if the small mic mixer has 8 jack/mono inputs (with level control on each) and specs say that device has 600 ohms inputS (plural!!!) and 1500ohms outputS..
(device is called stereo, but in fact all inputs r just mono holes. 2 groups of 4mono holes=total eight simple mono holes)

Soundlab G105DA MicroMixer | Laenenmusic.nl

http://www.amazon.co.uk/G105DA-Soundlab-Channel-Stereo-Microphone/dp/B0048FBBS8

1. so, does each of the inputs have 600 ohms, or its a total impedance of all connected sources/sum???

2. what kind of sources, instruments, mics can be used with it?? opinions on any usage, configurations, interesting useful applications, signal splitting, stereo panning/splitting?

3. as i understand, sources like electroacoustic guitars with much higher impedance cannot be used with this quite low impedance mixer??

4. if the signal is that low, that means this device needs lots of level gain increase and probably will generate quite noticeable hum/noise??
thankss
good day!
 
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The impedance is each jack, not total.

If you don't have this mixer yet, I would advise not to buy it. You want a mixer that has XLR mic connections and real mic preamps (assuming you want to use microphones). This has 1/4" unbalanced inputs. 600 ohms is correct impedance for standard mics, but not electric instruments.
 
This is a really cheap line mixer. You need one that is meant for mics and generally made for what you are trying to do.
Chances are, when you pick out an appropriate mixer, it won't run on batteries.
 
Farview said:
This is a really cheap line mixer. You need one that is meant for mics and generally made for what you are trying to do.
Chances are, when you pick out an appropriate mixer, it won't run on batteries.
Click to expand...

i completely agree.. but that will cost me 15bucks, so...
since my tascam audio card has only 2 balanced/unbalanced inputs, id like to add this cheap thing as a compromised addition.. to plug more mics.. for percussion or background vocals.. less significant sounds.. u know...

but as i know , input must have 10times more ohms than source.. For example, if a mic's impedance is 200 ohms, the input impedance of a mic input (that you plug the mic into) should be 7 to 10 times higher, or 1400 to 2000 ohms. If you look at the input impedance spec for mixer mic inputs, it is typically around 1500 ohms.
SO, HOW MIXER'S(ALSO IT HAS SOME KIND OF PREAMP INSIDE...) 600 OHMS CAN BE ENOUGH FOR MY SHURE57 (Rated impedance is 150Ω (310Ω actual) for connection to microphone inputs rated low impedance)??????????????????????????
PLS EXPLAIN...

danke very much.
 
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richardosim78 said:
i completely agree.. but that will cost me 15bucks, so...
since my tascam audio card has only 2 balanced/unbalanced inputs, id like to add this cheap thing as a compromised addition.. to plug more mics.. for percussion or background vocals.. less significant sounds.. u know...

but as i know , input must have 10times more ohms than source.. For example, if a mic's impedance is 200 ohms, the input impedance of a mic input (that you plug the mic into) should be 7 to 10 times higher, or 1400 to 2000 ohms. If you look at the input impedance spec for mixer mic inputs, it is typically around 1500 ohms.
SO, HOW MIXER'S(ALSO IT HAS SOME KIND OF PREAMP INSIDE...) 600 OHMS CAN BE ENOUGH FOR MY SHURE57 (Rated impedance is 150Ω (310Ω actual) for connection to microphone inputs rated low impedance)??????????????????????????
PLS EXPLAIN...

danke very much.
Click to expand...
No that's kuz ur rite!
Not to mention by the time you pay for XLR-to-TRS adapters to even use mics with this thing ...you'd spent half way to a proper piece of kit that does do it right!
There. Is s plained.
 
First thought is that it's telling you not its actual impedance, but rather the expected impedance of the things you'd connect to it. Else maybe they got the stats backwards. 1500 ohm in-Z is still kinda low, but 600 out would be pretty good.

Don't confuse impedance with levels, though. If the impedances aren't (mis)matched properly, there can be a loss of level (broadband and/or frequency specific), but there is no way to correlate impedance directly to nominal or maximum level in any device.

Also you may have meant something different by "electro-acoustic" but that makes me think of an acoustic-electric guitar. Those normally have active preamps which have pretty low out-Z. It's the passive magnetic pickups in most regular electric guitars that are very high, and need really high in-Z to sound best.
 
mixsit, u r rite, man... but all i have is a couple of extra xlr to jack cables, and ,... 15 bucks...

ashcat_lt, yes, maybe it is backwards!!! then everything would fall into place...but all the websites featuring this product write the same values..
why do u think i confuse impedance with levels?? all i know is that bad impedance causes bad (often high) level knob settings and produces unacceptable hum, noise.. thats why im asking about impedance of that mixer..

and, yes, acoustic-electric guitar,, they r low z because of battery preamp.. what is typical output impedance of such guitars.. i have ordinary ibanez with aeq200 eq's.??

p.s. though my souncard has hiZ input, but i always use miking for electric guitars.. oh and sorry for my non native english..
 
That mixer has NO mic preamps, even with XLR-1/4" adapters, the sound is going to be low and noisy - and you realize that this will not give you MORE separate tracks in your DAW (with your tascam 'card') right?
 
mjbphotos said:
That mixer has NO mic preamps, even with XLR-1/4" adapters, the sound is going to be low and noisy - and you realize that this will not give you MORE separate tracks in your DAW (with your tascam 'card') right?
Click to expand...

Hmm, just a passive (or op amp) blend then. If that's the case good catch. I didn't go past the initial suspicious "mic inputs" on TS jacks
 
mjbphotos said:
That mixer has NO mic preamps, even with XLR-1/4" adapters, the sound is going to be low and noisy - and you realize that this will not give you MORE separate tracks in your DAW (with your tascam 'card') right?
Click to expand...

no peamp?? so how then it has all these level knobs and 2 master knobs.. i guess it has some kind of amplification/leveling inside..hmmm???
passive (or op amp) blend?? gotta do more research.. interesting...

and yes, that mixer will be as one chanel. one mono chanel.. but i can record more participants on that channel alone with more mics..
and if i would use two such mixers, i could record in stereo with many participants/musicians/instruments on each side!
thats my goal!

btw, less cheep amps inside, more transparent the signal...so.. anyway.. my soundcard should amplify them...
 
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Richard - it's what used to be called a summing mixer - it takes in line level signals, and mixes them together. The electronics internally are just there to keep the output level up, and provide line driving.

We're using the term pre-amp to mean the type of electronics designed to get a microphone level signal up to line level so it can be recorded or sent to a PA, or video system. In most cases, these also allow balanced audio to enter the mixer, via XLRs, which performance wise are the standard, nowadays. If you plug a mic into it, using either a rubbish mic that has a jack on it (perhaps fresh from karaoke), then it's not going to work, unless you then used a mic level preamp on the output - and if you did that, up would come the noise to a yukky degree.

It's simply not a mixer for microphones, and to be fair, doesn't pretend to be. It mixes sources to outputs. In this case, it's a bit specialised - in that it can do two independent mono mixes from the four inputs - so quite unlike most mixers. It's two four way mono mixers in one box. I'd find a use for it, but not for recording with mics.
 
This piece of kit is no use to you.
It's not designed to accept microphone inputs.

Go and plug a microphone into a line level input on a hifi or something to see what happens. ;)
 
richardosim78 said:
why do u think i confuse impedance with levels??
Click to expand...
Perhaps I misunderstood this:
4. if the signal is that low, that means this device needs lots of level gain increase and probably will generate quite noticeable hum/noise??
Click to expand...
shrug.

I have had reasonable (not to say great) results plugging mics via XLR>TS cables directly into line level inputs and recording to digital where any gain you get is essentially noise free. It is still compromising the S/N ratio to quite an extent, but with loud sources and sensitive mics it can sort of work. I would also discourage you from getting this particular thing for your state purpose, but I can see where it could come in handy in a lot of situations. Might be worth grabbing it to limp along until you can save up for a mixer with half-way decent pres. Then you'd have it around for mixing anything with anything any time you might need it. But then I have a couple more than $15 to my name...
 
rob aylestone said:
It's simply not a mixer for microphones, and to be fair, doesn't pretend to be. It mixes sources to outputs. In this case, it's a bit specialised - in that it can do two independent mono mixes from the four inputs - so quite unlike most mixers. It's two four way mono mixers in one box. I'd find a use for it, but not for recording with mics.
Click to expand...

well it says its a microphone mixer... G105DA Soundlab 4 Channel Stereo Microphone Mixer. not xlr but mono jacks... well... i know..
also, if it has level knobs, that means it has some kind of amplification of the incoming levels?!?...hmmm...
u 'd find a use for it, but not for recording with mics?? what would u use it for then??..
 
ashcat_lt said:
Might be worth grabbing it to limp along until you can save up for a mixer with half-way decent pres. Then you'd have it around for mixing anything with anything any time you might need it. But then I have a couple more than $15 to my name...
Click to expand...

well was defending my honor and was left with $15....:( but i dont regret... and never will...

and thanks for answers..
 
I bought one of these kinds of things made by Eagle in 1974, and sonically with microphones they are the musical equivalent of running your car on paraffin - it's the wrong product. If you want to yell into a mic and call some bingo on a rubbish PA, it will do fine - but quality wise, why would you even wish to attempt it? No balanced inputs, a high noise device, no conventional stereo pan controls, and simply a few pots wired with the wiper to a isolating resistor - all commoned up with a cheap amp o the output to bring the level back up.

There is no reason to buy this product unless you need to mix some CDs together, or merge some line level streams.

I have had reasonable (not to say great) results plugging mics via XLR>TS cables directly into line level inputs and recording to digital where any gain you get is essentially noise free. It is still compromising the S/N ratio to quite an extent, but with loud sources and sensitive mics it can sort of work.
Click to expand...

So if you want not great results, unbalance your mics, replace professional connectors with jacks, and yell into them? Why would you wish to have not great results? I just don't see the point in using the wrong kit, for the wrong purpose and putting up with the wrong results.

Why not buy a cheap Behringer or similar, with proper sockets, proper facilities and performance that isn't an embarrassment.
 
rob aylestone said:
So if you want not great results, unbalance your mics, replace professional connectors with jacks, and yell into them? Why would you wish to have not great results? I just don't see the point in using the wrong kit, for the wrong purpose and putting up with the wrong results.
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Err...Because it's what you've got and it gets the job done? Not ideal, maybe, but honestly not as bad as you might think. I actually had people speaking at conversational levels and was able to use the tracks just fine. Course, there was a lot going on in these mixes, and most of the extra noise was masked by that. It won't work for audio books...

Honestly, if comes down to doing it "wrong" and not doing it at all, I'll choose to capture the performance as best I can (even if that's less than perfect) every damn time.
 
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