sound recording in hmc150

A

Amos Kim

Active member
anybody know if the sound recording component of the hmc150 can be damaged from too loud of sound? I'm wondering if I can record safely at a really loud music concert in camera. thanks
 
I am giving an educated guess and if I am in error someone jump in. I don’t think you can damage a component/stage of the HMC 150 using almost any type of microphone. Most microphones cannot develop large enough voltages that would damage an input stage of a microphone pre-amplifier. What is going to happen is you will overload the stage and cause clipping which is a bad thing for the recorded material. If the preamps are not overloaded because of sufficient headroom then a following stage or the analog-to-digital converter will hit a hard limit and again cause heavy distortion of the signal. There are only so many bits that are available in the conversion process. The microphone could be overdriven and then you have a distorted signal before it even enters the camera.
 
Regardless of the possible damage factor, there have been many posts here about high spl on the 150. It has been reported that the 150 clips excessively or performs poorly when high spl are encountered. Most of these threads were shortly after the introduction and have died down lately. Search is your friend. The best way to record to the 150 would be to use external mics and a mixer with good limiters. That would be true for any cam or other recording device, especially in loud environs. If you are planning on moving around with the cam, you might want to consider a remote recording device and add the sound trax in post.

Grant
 
thanks for the input guys. Can anybody confirm jwrtiger's theory about possible damage?
 
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ggrantly said:
Regardless of the possible damage factor, there have been many posts here about high spl on the 150. It has been reported that the 150 clips excessively or performs poorly when high spl are encountered.
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This will happen on ANY camera or recorder...if you pound the level...it will distort!


The best way to record to the 150 would be to use external mics and a mixer with good limiters. That would be true for any cam or other recording device, especially in loud environs. If you are planning on moving around with the cam, you might want to consider a remote recording device and add the sound trax in post.

Grant
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That's the ticket!

I have never had a problem using external mics with my HMC150... but I use a SD722 and take a feed from that to the camera. I then have redundent recordings.
 
Zaza or anybody else, so if I do pound the levels and distort, will it damage the camera's internal sound recording hardware?
 
You don't tell us HOW you will film your loud concert, will you be filming with the internal mic close to the speakers? This would not give you a good sound. But no, it will not break the internal microphone hardware. It may just gives you a distorted sound.

If you want to put an external mic close to a speaker, you should use a cardioïd mic like a SM57.

But usually, you should require an output feed from their mixer and set the audio input to Line level instead of Mic level.
 
I like your idea of "an output feed from their mixer and set the audio input to Line level instead of Mic level" Thanks for input Sprimeau.
 
I would not think pounding the levels or causing distortion would in any way harm the recording electronics. I am not an expert but I have built several microphone preamps from scratch. I don’t have the schematic for the HMC 150 and I will probably never try and take it apart. I am assuming that since there are so many features and functions in this great camera that it is probably all surface mount technology and integrated circuits for the audio and converter chain. On most microphones that would be used with the HMC 150 I would think output levels would be in 10’s to 100’s of millivolts. Most surface mounted components I have played with are rated at tens to several hundreds of volts. One area that can cause damage is if the input source material exceeds the power supply rails of the integrated circuits. So if the power to the preamps do not have inverters we are probably looking a 6 to 10 volts. Peak source voltage for the AT897 microphone at maximum input level of 129 dB SPL results in an open circuit voltage of 0.615 Vp. So you can see you have a very small voltage compared with input limits on a preamplifier. Please note this is a very crude estimation because you will be dealing with a very corrupted signal with high distortion by the time you reach that level. I am also not looking at power output and noise figures. Also there are mic’s that have built in attenuators and you can always get an inline attenuator if needed. If you have a truly hot signal coming in and using the manual level controls another problem is you may have very poor adjust range because you will be near the bottom of the control’s range.
Again take this with a grain of salt because I left out other parameters.
 
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