PCM1804DB used as input for typical Audio XLR microphone

Donald Golding

Other Parts Discussed in Thread: PCM1804

Can you use this chip alone or do you need and op-amp input to boost the gain to acceptable levels for the ADC.

I am designing an audio amplifier using the TAS5508 and TAS5142DKDG4 combination using this chip for differential audio input for the TAS5508.

I need to support both single ended and differential inputs for a stereo commercial grade 40 watt D-Amp. The input needs to support both music microphone XLR inputs, electric guitars, keyboards, etc.

Thanks,

Don

over 14 years ago

0 Donald Golding over 14 years ago

Prodigy 30 points

I looked up a typical microphone such as this...

Shure C606-WD All-Purpose Dynamic Microphone

http://beststudiomic.homepage.ph/2010/05/06/shure-c606-wd-all-purpose-dynamic-microphone-with-xlr-cable-and-14-inch-adapter/

It has a 0 DB output which should be about .775 volts.

Is this enough voltage for the PCM1804DB to digitize the voltage with minimum distortion? I would like to keep the distortion under .1 percent min, with .01 percent optimum.

Thanks again,

Don

0 Don Dapkus over 14 years ago in reply to Donald Golding

TI__Guru**** 189401 points

Hi, Donald,

I think you should definitely put some ESD protection and signal limiting so you don't exceed the input capabilities of the PCM1804.

Also, you probably want some gain, 0.775V is pretty low.

-d2

0 J- over 14 years ago

TI__Mastermind 46195 points

Hi Donald,

You plan to use something like this, right? http://www.neutrik.com/client/neutrik/media/products/view/210_941139929.jpg

You would definitely want to have some type of variable gain on the input amp, especially if you plan to hook up guitars into it.

As Don mentioned, it is very important to put some sort of ESD suppression chip or circuitry for any trace that interface the outside world to a chip pin. Also, it would be good to have some sort of input limiter to prevent the input signal from exceeding VDD or going below ground (maybe some diodes) per the datasheet's recommended operating conditions.

Regards,

J-

0 Donald Golding over 14 years ago in reply to J-

Prodigy 30 points

There is a reference pin on the device which sets the max ADC voltage which can be used as a "level" control - Simply place a pot on it for max level adjustment.

Don

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PCM1804DB used as input for typical Audio XLR microphone

Shure C606-WD All-Purpose Dynamic Microphone