bouldersoundguy
Well-known member
I need one of those. No, I need three of them. But I get by okay with a multimeter, even if it means fumbling with the probes sometimes.
Unable to get good signal to noise ratio - what's the issue?
JimmyS1969
MOODerator
Well worth the money IMO. Easy way to troubleshoot on the fly.
Multimeter later when fixing obviously...
Multimeter later when fixing obviously...
J
jajsound#5
New member
Ebtech Swizz-CT Swizz Army 6-in-1 Cable Tester
Is a must for Live Situations, and Studio......
Is a must for Live Situations, and Studio......
E
ecc83
Well-known member
"Balanced signals have a ground, a "hot" and a "cold". Ground is the stable reference point, hot is the signal and cold is the mirror image of the signal."
Don't want to get too tekky-pedantic BSG but err, not quite. "Proper" balanced signals, whether they come from an amplifier in each "leg" or a transformer are NOT referenced to earth/ground/chassis.
Yes, such signals are almost* always sent over shielded leads but the shield simply adds extra RF interference protection, strictly speaking you don't need it (you do of course for the phantom power -ve "return") . It is often said that balanced operation can fix earth loop problems? Well yes, it often does but it is not its prime purpose and sometimes it don't! In such cases you can remove the shield connection one end, with impunity, except in rare cases where there is a high RF field (but there is a fix for that too!).
*Back (waaaay back!) in the day we used twin twisted mains cable for MIC cables but the mics were 30Ohm units running into 1:60 transformers and triodes both of which components gave high RF rejection.
Then, 100 volt PA speaker lines are (or bloody should be!) balanced and not screened.
Dave.
Don't want to get too tekky-pedantic BSG but err, not quite. "Proper" balanced signals, whether they come from an amplifier in each "leg" or a transformer are NOT referenced to earth/ground/chassis.
Yes, such signals are almost* always sent over shielded leads but the shield simply adds extra RF interference protection, strictly speaking you don't need it (you do of course for the phantom power -ve "return") . It is often said that balanced operation can fix earth loop problems? Well yes, it often does but it is not its prime purpose and sometimes it don't! In such cases you can remove the shield connection one end, with impunity, except in rare cases where there is a high RF field (but there is a fix for that too!).
*Back (waaaay back!) in the day we used twin twisted mains cable for MIC cables but the mics were 30Ohm units running into 1:60 transformers and triodes both of which components gave high RF rejection.
Then, 100 volt PA speaker lines are (or bloody should be!) balanced and not screened.
Dave.
bouldersoundguy
Well-known member
Quite right, ground is not needed for the balanced signal to pass. I thought for the OP's purposes I'd keep it simple.
You mention active and transformer balanced outputs. What about impedance balanced outputs? What happens if you lift that ground? Same as the others I would think, just a loss of shielding.
But we are getting a bit off course here.
E
ecc83
Well-known member
Yes, I agree we should keep things simple (one reason why I avoided Z balance) but at the same time I think actual inaccuracies should be avoided?
People are very confused about balanced systems in general and I think it behoves us to stick to the facts. As for lifting a ground on an impedance balanced line? Can only be done at the remote end by definition but much the same result should obtain, i.e. removal of ground loop hum. Maybe not AS effective as "proper" balance because the remote earth is still tied to source by 100Ohms or so but probably good enough in practice.
It is a fact however that "signal transfer" can be a bit of a black art/lucky dip! Every situation is different and we have to just do the best we can.
There is however one Golden Rule? NEVER LIFT MAINS SAFETY EARTHS!!!
And! So long as things don't get silly or abusive I like a bit of a ramble!
Dave.
bouldersoundguy
Well-known member
I guess the way I was looking at it somewhere there still is a ground reference, even if it's on the other side of a transistor, transformer or resistor, and the shield is connected to that.
And because it cannot be said too strongly or too often:
NEVER LIFT POWER GROUNDS!!
R
RockDiedin2005
New member
Guys I (we) finally solved everything! Thanks to all who helped me through the troubleshooting process and helped me learn.
The SV100 is a high-impedance microphone. 600 ohms. The audio interface treats a 600 ohm signal as needing the hi-Z switch - which, I had falsely interpreted as being a button that would RAISE the impedance, therefore lower the signal.
Once I tried using it with the XLR-TS and with hi-Z pressed, the signal finally become clear as a bell. Noise floor at -96, peaks at -18 when singing softly.
Of course, the 60 hertz buzz was a different issue. I did try using a different, better quality XLR cable and it did not suffer the buzz. (It was actually still present, but much, much quieter than with the low quality cable, only becoming audible if I'd grasp the connector at the audio interface end. That means it was somehow a form of ground interference which was greatly amplified by using a shit-grade cable, and for whatever reason is not picked up at all by the XLR-TS cable supplied by Shure.)
So the lesson for other newbs iiiis (and this is something that should be written in the effin manual to begin with): check the impedance of your mics, and treat any 600+ ohms mics as you would an electric guitar or bass connecting direct.
/Thread (drops the mic)
The SV100 is a high-impedance microphone. 600 ohms. The audio interface treats a 600 ohm signal as needing the hi-Z switch - which, I had falsely interpreted as being a button that would RAISE the impedance, therefore lower the signal.
Once I tried using it with the XLR-TS and with hi-Z pressed, the signal finally become clear as a bell. Noise floor at -96, peaks at -18 when singing softly.
Of course, the 60 hertz buzz was a different issue. I did try using a different, better quality XLR cable and it did not suffer the buzz. (It was actually still present, but much, much quieter than with the low quality cable, only becoming audible if I'd grasp the connector at the audio interface end. That means it was somehow a form of ground interference which was greatly amplified by using a shit-grade cable, and for whatever reason is not picked up at all by the XLR-TS cable supplied by Shure.)
So the lesson for other newbs iiiis (and this is something that should be written in the effin manual to begin with): check the impedance of your mics, and treat any 600+ ohms mics as you would an electric guitar or bass connecting direct.
/Thread (drops the mic)
E
ecc83
Well-known member
SO! Glad you have found a solution!
However I am not at all convinced that things are as they should be. First off, a 600 Ohm mic is assuredly LOW impedance. Microphones used to come in all sorts of impedances years ago, many were nominally 30 Ohms (tho' I have a Geloso lavalier type that is 15 Ohms!) and up from there but 600R was still in the vanguard of "low". Actual "high" impedance mics incorporated a transformers that stepped up both Z and volts to 50k Ohms or so and these were designed to drive valve tape recorders and valve PA amps.
The C11's mic input has a specified load Z of 3k and so being 5X 600R should be fine with that mic (there will be a quite unnoticeable 1.6dB loss). The fact that it isn't tell me there is still an underlying problem.
"High, medium, low" impedance are not fixed in stone and there is also a lot of confusion whether folks are talking of sources or "sinks" but "high" (load) would be 100k and up. Medium down to 2k or so and low anything much below that. Of course these terms are often application specific.
There is also a problem in the system re the "touchy/feely" hum issue. A properly implemented and grounded system should not be influenced by the presence or absence of the dab sinister!
Again, so glad you have a workable setup now but I await with interest the results of a test with an SM57 or similar or a metering on the SV100!
Dave.
However I am not at all convinced that things are as they should be. First off, a 600 Ohm mic is assuredly LOW impedance. Microphones used to come in all sorts of impedances years ago, many were nominally 30 Ohms (tho' I have a Geloso lavalier type that is 15 Ohms!) and up from there but 600R was still in the vanguard of "low". Actual "high" impedance mics incorporated a transformers that stepped up both Z and volts to 50k Ohms or so and these were designed to drive valve tape recorders and valve PA amps.
The C11's mic input has a specified load Z of 3k and so being 5X 600R should be fine with that mic (there will be a quite unnoticeable 1.6dB loss). The fact that it isn't tell me there is still an underlying problem.
"High, medium, low" impedance are not fixed in stone and there is also a lot of confusion whether folks are talking of sources or "sinks" but "high" (load) would be 100k and up. Medium down to 2k or so and low anything much below that. Of course these terms are often application specific.
There is also a problem in the system re the "touchy/feely" hum issue. A properly implemented and grounded system should not be influenced by the presence or absence of the dab sinister!
Again, so glad you have a workable setup now but I await with interest the results of a test with an SM57 or similar or a metering on the SV100!
Dave.
bouldersoundguy
Well-known member
What he said. Glad it's working but the current state of symptoms suggests there's something fishy going on with the mic.
R
RockDiedin2005
New member
The tech specs I have show the hi-Z switch's input impedance to be 500 ohms. But it also says the Hi-Z input has 500KILO ohms vs XLR's 6K and TRS in normal state's 32K. It also shows the TRS' maximum input level to be +20dBu without hi-Z switch pressed, and down to +10 with it pressed.
So confusing. I thought more impedence = lower signal. Oh well.. I should stop trying to learn this stuff while my gear works.. it's a rabbit hole with no end..
E
ecc83
Well-known member
That specc' is bollox, the one in the full manual makes a lot more sense. I despair I really do! It beggars belief that a highly regarded audio company such as Steinberg/Yamaha could write such drivel! (mind you they DID forget to fit MIDI!).
Please don't give up on understanding audio signal paths, it IS all logical and the math very simple (well "I" can do it so it must be!) and, believe it or not all worked out by some clever sod long before such a thing as an "amplifier" ever existed!
Peeps get confused about these matter because, as I said before, it is often difficult to unravel what is a source impedance* and what is the input or load impedance. Very often for instance the OPZ of a piece of gear is given not as its source Z but as the load it is supposed to work into.
Things are vastly better than even ten years ago and so if we keep on telling the mfctrs to use LAB personell to write speccs instead of the AdPuff people they will get better!
The SV100 might just want to "see" 600R and in fact be of a lower Z.
Dave.