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#1
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Mic impedance - and some other things
Hi!
Finally I got my new Focusrite TwinTrak Pro. I bought it to be able to record my 4x12 Marshall cab with 2 mics, while being able to compress them altogether. Previously I used a Focusrite TrakMaster and a Behringer Ultra-Voice Pro for the 2 mics, but they weren't linkable. Now I find that the sound of the TwinTrak is much more enjoyable than that of the TrakMaster. The AIR button is really interesting... But I have a problem and that's my question. I use two different mics to capture my cabs sound: - Shure SM57 - Neumann KM 84i. I have some other mics but I found these 2 giving the best results. The new Focusrite TwinTrak has knobs to set mic impedance (60 - 3K Ohms). My real question is that how to set these knobs for the above mentioned two mics? Thanks a lot for answering! bence |
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#2
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whoops, my bad...
look up the rated load impeadance for those mics and set pre to those values Mark |
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#3
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Locsmándi Bence wrote:
But I have a problem and that's my question. I use two different mics to capture my cabs sound: - Shure SM57 - Neumann KM 84i. I have some other mics but I found these 2 giving the best results. The new Focusrite TwinTrak has knobs to set mic impedance (60 - 3K Ohms). My real question is that how to set these knobs for the above mentioned two mics? You'll find with the KM84 that it doesn't matter... the mike will sound pretty much the same no matter how the knob is set. With the SM57 you will find that the load changes the sound a lot, but you'll have to figure out which sound you want. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
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#4
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Thanks Scott for answering!
The SM57 manual says: "Rated impedance is 150 Ohms (310 Ohms actual)...." - which one to set? The KMi manual says: "The KMS has an electrical source impedance of 150 ohms. All the other microphones have an electrical impedance of 200 ohms. [...] The input inpedance of the following amplifier should be at least five times as great, i.e.= 1000 ohms or = 250 ohms respectiverly." - this is for a general manual for the KMi series. So, what value to go for? Thanks again! bence "Scott Dorsey" az alábbiakat írta a következő hírüzenetben: ... Locsmándi Bence wrote: But I have a problem and that's my question. I use two different mics to capture my cabs sound: - Shure SM57 - Neumann KM 84i. I have some other mics but I found these 2 giving the best results. The new Focusrite TwinTrak has knobs to set mic impedance (60 - 3K Ohms). My real question is that how to set these knobs for the above mentioned two mics? You'll find with the KM84 that it doesn't matter... the mike will sound pretty much the same no matter how the knob is set. With the SM57 you will find that the load changes the sound a lot, but you'll have to figure out which sound you want. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
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#6
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You can read about it in my first letter.
Anyway, they are an SM57 and a Neumann KM 84i. Thanks b. "Mark" az alábbiakat írta a következo hírüzenetben: ... what are the mics connected to? Mark |
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#7
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On Mon, 11 Apr 2005 22:46:53 GMT, "Locsmándi Bence"
wrote: Thanks Scott for answering! The SM57 manual says: "Rated impedance is 150 Ohms (310 Ohms actual)...." - which one to set? Reread the last sentence Scott wrote below. You'll have record something at each setting of the switch, then listen back, and then (this could be the hardest part) decide which setting gives the sound you like best (for that particular guitar/amplifier/song). The KMi manual says: "The KMS has an electrical source impedance of 150 ohms. All the other microphones have an electrical impedance of 200 ohms. [...] The input inpedance of the following amplifier should be at least five times as great, i.e.= 1000 ohms or = 250 ohms respectiverly." - this is for a general manual for the KMi series. So, what value to go for? As Scott says below, it doesn't matter (phantom-powered mics have small preamps that buffer the element, eliminating changes in tone due to different loading, though there may still be slight changes in volume), but I'd go for the highest setting, to put the least load on the mic and give the most voltage transfer. OTOH, try each setting and see if Scott is right in saying it will likely sound the same. Thanks again! bence "Scott Dorsey" az alábbiakat írta a következő hírüzenetben: ... Locsmándi Bence wrote: But I have a problem and that's my question. I use two different mics to capture my cabs sound: - Shure SM57 - Neumann KM 84i. I have some other mics but I found these 2 giving the best results. The new Focusrite TwinTrak has knobs to set mic impedance (60 - 3K Ohms). My real question is that how to set these knobs for the above mentioned two mics? You'll find with the KM84 that it doesn't matter... the mike will sound pretty much the same no matter how the knob is set. With the SM57 you will find that the load changes the sound a lot, but you'll have to figure out which sound you want. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." ----- http://mindspring.com/~benbradley |
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#8
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Locsmándi Bence wrote:
The SM57 manual says: "Rated impedance is 150 Ohms (310 Ohms actual)...." - which one to set? The KMi manual says: "The KMS has an electrical source impedance of 150 ohms. All the other microphones have an electrical impedance of 200 ohms. [...] The input inpedance of the following amplifier should be at least five times as great, i.e.= 1000 ohms or = 250 ohms respectiverly." - this is for a general manual for the KMi series. So, what value to go for? Scott's answer was right on (no surprise) but he left out some details that might help you better understand it. A SM57 is a dynamic mic. Its output terminals are attached to a coil of wire wrapped around an iron core (a trnasformer) that eventually leads to another coil of wire, a core and a magnet (the mic element). The coils of wire, etc. have substantial inductance, resistance and even some capacitance. How they respond somwwhat depends on what else you attach across the mic's output terminals. On balance, the SM57 is designed to be fairly resistant to changes in its response due to loading. Most of the effects are at higher frequencies, some above the audible range. The Neumann KM 84i being a condensor mic apparently still has a transformer, but due to the presence of an electronic buffer (powered by the phantom voltage) it is less susecptible to changes in response due to loading. |
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#9
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#10
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On 4/12/05 5:53 PM, in article znr1113272772k@trad, "Mike Rivers"
wrote: In article writes: The SM57 manual says: "Rated impedance is 150 Ohms (310 Ohms actual)...." - which one to set? The one that you think sounds best. If you can't tell any difference in the sound as you switch through the available choices, pick one that's typical of most modern preamps, 1000 to 2000 ohms. I guess we shouldn;t wonder about what year 57 it is... And whether there's a transformer IN there or not (used mics are Fascinating). |
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#11
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Linear Mode
