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Old 13th November 2016, 09:09 PM   #1
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Default Dynamic microphone preamp

I want to build a dynamic microphone preamp. Do any one of you has any tested good quality circuit diagram of dynamic mic preamp? The circuit should be simple and must have an option to control gain. Thanks in advance.
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Old 13th November 2016, 10:26 PM   #2
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This link

Microfoonversterkerontwerpje voor de liefhebber - forum.zelfbouwaudio.nl

points to the schematics and a description in Dutch of my home-made microphone amplifier, which works well with both dynamic and phantom-powered condenser microphones.
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Old 16th November 2016, 09:20 AM   #3
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An OPA1611 (single) or OPA1612 (dual) is the best op amp available for microphone preamplifier applications. Their noise, distortion, common-mode, and speed specifications can't be topped. Here's a link to some circuits using it:
https://sites.google.com/a/vt.edu/am...e-preamplifier
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Old 17th November 2016, 10:15 PM   #4
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The op-amp is pretty good, but the amplifier design isn't. At least to me it doesn't make much sense to buy a 1.1 nV/sqrt(Hz) op-amp and then connect a 4 nV/sqrt(Hz) resistor in series with its input. A noninverting amplifier topology with very low-ohmic feedback network would be much better, especially for dynamic microphones.
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Old 18th November 2016, 05:50 AM   #5
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Quote:
Originally Posted by MarcelvdG View Post
The op-amp is pretty good, but the amplifier design isn't. At least to me it doesn't make much sense to buy a 1.1 nV/sqrt(Hz) op-amp and then connect a 4 nV/sqrt(Hz) resistor in series with its input. A noninverting amplifier topology with very low-ohmic feedback network would be much better, especially for dynamic microphones.
Yes, I see your point. Would you have a link to a better schematic?
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Old 18th November 2016, 05:52 AM   #6
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Not with an OPA1611. Otherwise see post 2, although its distortion is certainly worse.
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Old 18th November 2016, 09:19 AM   #7
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Certainly
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Old 20th November 2016, 10:14 AM   #8
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This one is pretty simple & inexpensive. I would substitute an OPA1612 for the NE5532, but either would be fine.
Project 122
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Old 26th November 2016, 08:40 PM   #9
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I'm no expert, but I've read great things about the THAT 1510 and 1570, for high gain audio applications. IIRC, THAT has some circuit diagrams on the website.

Other chips that get raves for audio, but not specifically mic pres:


LT1469
ADA4898
TLE 2082 Excalibur
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Old 28th November 2016, 09:51 AM   #10
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THAT 1510/12--- awful THD specs
ADA 4898----good noise & distortion specs; high current draw; low maximum output voltage swing
TLE 2082---very fast, very noisy, high distortion. A JFET device==not optimum for microphone preamps
The OPA 1612 is much superior in all respects.
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