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Microphone and mic preamp impedence matching
Old 29th April 2007
  #1
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HIGHENDONLY's Avatar
 

Microphone and mic preamp impedence matching

I just wanted to know if this is a big factor in making your mic sound it's best. I read where the impedance on the mic pre should be 10 times that of your microphone.
I have the c800g and i found out its output is 100ohms..
So would i need a mic pre of 1000-1200ohm mic pre to hear its potential??
I also have a martech mss10 and i just saw it has a input of 2450 ohm's now would that actually be a bad match for my sony?

Can sometimes explain this to me...thank's
Old 29th April 2007
  #2
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WunderBro Flo's Avatar
what you said just with the addition "at least 10 times"
- higher than 10 times can only be "better" technically. only when it´s lower then it can get technically weaker...

cheers,
Pat
Old 26th August 2007
  #3
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I'm trying to gain a better understanding of this subject myself.

I see that 5 to 10X the imedance of the microphone is recommended at the preamp, but then what about preamps like the A-Designs Pacifica that have impedance set at 600 ohms. Most (if not all) of my mics should be supplied with a load of at least 1k ohm according to their documentation. Is the lesser load ok?
Old 27th August 2007
  #4
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Quote:
Originally Posted by PheelTheMusic View Post
I'm trying to gain a better understanding of this subject myself.

I see that 5 to 10X the imedance of the microphone is recommended at the preamp, but then what about preamps like the A-Designs Pacifica that have impedance set at 600 ohms. Most (if not all) of my mics should be supplied with a load of at least 1k ohm according to their documentation. Is the lesser load ok?
It depends alot on the mic, some mics load easier than others. Most condensers will handle a lower imp. load better than most dynamics because they have some amplification.
The 600 ohms sounds a little low to me.
Old 27th August 2007
  #5
I've always understood it to be 1 to 6 ratio, mic being the 1 preamp being the 6. But I personally think that at this point it's anything goes...the Neve type designs all have 300 ohms on the low part of the switchability, and there have been some great tones created that are 'against the rules' on that setting. Just use your ears.
Old 27th August 2007
  #6
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10x nominal impedance is a defacto design standard. Microphone makers, at least anything from the last few decades should anticipate this termination when voicing the mic.

Preamps that deviate significantly from this nominal 10x may be fishing for a slightly different frequency response to help differentiate their "sound" from more conventional designs, for marketing purposes. If expensive and "sounds" different, some percentage of listeners will perceive that difference as an improvement. Classic problem for high end designers is trying to sound different, otherwise what's the point of spending more money?

If you want the mic to sound like the mic designer intended, I'd stick to standard terminations. If looking for different, try different, but generally you could mimic the frequency response shift with a little EQ. Too low of an input termination may also degrade S/N.

JR
Old 27th August 2007
  #7
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Standards may be "recommended", but I don't think there's a right or wrong way on this, it's just how it sounds. For instance, I'm running a Pearlman TM1(600 Ohm) into a GT Vipre at 1200 Ohms, and it's perfect for the sound I'm after - tonally it fits this project way better than say, the bridged impedance setting, which is very high. If I click it over to 600 to match the mic, the sound becomes a little thicker and more up-front/intimate, but still excellent. I might like that for another song..

I have even used 600 Ohm mics into 300 Ohms preamp settings with great success- long as it doesn't blow up, I'm good.

For me it's a bigger job to match the mic with the right pre in the first place, then who cares about the impedance? But it's still a good question HIGHEND.
Old 27th August 2007
  #8
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Quote:
Originally Posted by NathanEldred View Post
I've always understood it to be 1 to 6 ratio, mic being the 1 preamp being the 6. But I personally think that at this point it's anything goes...the Neve type designs all have 300 ohms on the low part of the switchability, and there have been some great tones created that are 'against the rules' on that setting. Just use your ears.
What neve pre has a 300 ohm input?
also would be hard to use your ears, hard to A/B the loading effect..
Old 27th August 2007
  #9
Quote:
Originally Posted by nosebleedaudio View Post
What neve pre has a 300 ohm input?
1073...the ability to switch to 1200 is not on the front panel though. I can't remember if the 1084 has it also, I'm not a Neve expert.


Quote:
also would be hard to use your ears, hard to A/B the loading effect..

On pieces like the Great River, Vintech, Groove Tubes, Buzz Audio Elixir and MA2.2, and soon our new 500 series Atlas Pro preamp, the impedance is switchable, and sometimes very noticeable depending on the microphone. So it's easy to listen to the contrast between loading in real time, instantaneously.
Old 27th August 2007
  #10
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Quote:
Originally Posted by NathanEldred View Post
1073...the ability to switch to 1200 is not on the front panel though. I can't remember if the 1084 has it also, I'm not a Neve expert.





On pieces like the Great River, Vintech, Groove Tubes, Buzz Audio Elixir and MA2.2, and soon our new 500 series Atlas Pro preamp, the impedance is switchable, and sometimes very noticeable depending on the microphone. So it's easy to listen to the contrast between loading in real time, instantaneously.
This is true, I was referring to a pre that ONLY has say 600 ohm, how would you know how it would sound on the same pre at say 1500 ohms.
That was the point I was attempting to make but failed...
I did notice on the GTQ pre it has a switch for 300 ohm, IM wondering if its a different tap on the trans or a pad so that the mic "See's" a 300 ohm load, not trying to get picky..
Old 29th August 2007
  #11
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If the Pearlman TM1 is 600 ohms and the A-Designs Pacifica is only 600 ohms as well, wouldn't the 1:1 ratio certainly affect the performance of the combo?

The pair get rave reviews so is this just random uck or is there more to it?...
Old 29th August 2007
  #12
TRW
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Quote:
Originally Posted by nosebleedaudio View Post
This is true, I was referring to a pre that ONLY has say 600 ohm, how would you know how it would sound on the same pre at say 1500 ohms.
That was the point I was attempting to make but failed...
I did notice on the GTQ pre it has a switch for 300 ohm, IM wondering if its a different tap on the trans or a pad so that the mic "See's" a 300 ohm load, not trying to get picky..
Transformer tap.

The varying taps on a transformer change the turns ratio and the gain will adjust (drop or rise) accordingly so its harder to A/B in fair comparison.

Typically the lower turns ratios can be somewhat cleaner...but thats not always the case. Lots of variables.

The load presented to the mic can provide damping for any resonances that occur from the mic and cable inductances (especially with dynamic mics).

-T
Old 30th August 2007
  #13
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Quote:
Originally Posted by TRW View Post
Transformer tap.

The varying taps on a transformer change the turns ratio and the gain will adjust (drop or rise) accordingly so its harder to A/B in fair comparison.

Typically the lower turns ratios can be somewhat cleaner...but thats not always the case. Lots of variables.

The load presented to the mic can provide damping for any resonances that occur from the mic and cable inductances (especially with dynamic mics).

-T
And the highs are the first the be attenuated.
Loading a mic gives a darker sound.
And this might be just the sound someone wants...That's what it's all about...
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