Recording peak amplitude of muzzle blast

There is no spec for maximum level, but it is probably about 130dB (if you are lucky). To record peak level from the gun, it will need to be good for about 170dB. 40dB of attenuation is probably not easy to find, but a quick and easy way to get you somewhere near would be to peel off the felt cover and put a blob of glue over the sound hole. These capsules are cheap, so buy more than you need so you can experiment.

For peak detection, how about using a laptop and sound card with four inputs? You can then record the sounds and perhaps do more with them later.

x-no-archive:

I have 3 suggestions for you:

2) yes you probably need an mechanical attenuator or use a mic that will not clip at high SPL levels.

Mark

Those will definately have a limitation. You can get better performance from them by modifying them and of course, using maximum applied voltage.

I would ask rec.audio.pro

A mechanical attenuator might be too variable. I am getting maximum SPL of 120

-130 in some reading. There might be a method to increase the maxim rating by using different resistors. I don't have the answer off hand, but anyway a link to my microphone page...

greg

On a sunny day (Thu, 29 Jan 2009 16:03:43 GMT) it happened snipped-for-privacy@zekfrivolous.com (GregS) wrote in :

I severely doubt the effectiveness of putting 47nF mylar in parallel with 6.8uF tantalum for audio in this circuit. You must be an audiophool.

Now, for fun, try to calculate the impedance of 47nF at 20kHz. It is 1 / j.w.C, where 'w' stands for Omega = 2 x PI x f, or without the complex part 1 / 6.28 x 20 000 x 47 x 10^-9, makes 100 000 / (6.28 x 2 x 47) = 169 Ohm. At lower frequencies it will be much higher.

Tantalum caps have very low ESR in the milli Ohms range at that frequency.

Stop posting from an EDU, it makes the EDU look ridiculous.

I stopped reading your site there, as this shows you do not know what you are doing. El Pante.

Pretty much why I said not criticle.

Who cares

Your very right for comments about those caps. Its nothing more than a reprint from an article done way back. 3rd month of 1985 Speaker Builder Magazine. The caps are generic, and only specified for the people who might think they are necessary, and when you mix and match, who knows what they are going to use anyway.

greg

On a sunny day (Thu, 29 Jan 2009 17:37:50 GMT) it happened snipped-for-privacy@zekfrivolous.com (GregS) wrote in :

So, so also have to lookup the meaning of critical:

I'd say: It is not needed at all.

The essence is, is that learning, in this society, is often parroting something, like chanting '1+1 makes 2' etc... When you start _designing_, or being in any way creative other then repeating, that no longer works.

We should have more understanding and less copy-cat. In this specific case it would save 2 capacitors multiplied by the number of people who actually build that circuit. The world would be greener .... LOL

Sorry about the empty post. Regarding the laptop, I didn't think it would sample fast enough to make sure I get the peak of each pulse. Expand more on that if you think it's fast enough. Thanks, Mike

It would be determined by the AD stage, stages, speeds and memory. I did have the idea of sampling also with one additional mike, attenuated and distanced for a linear comparison.

I think using a dynamic mic is what you will need.

greg

Around that time the goverment in the US took off the MPG yearly requirments to improve the economy to increase sales and make big SUV's. It made green money. They were thinking the wrong kind of green.

greg

It will certainly sample fast enough to record the output of a microphone - which is after all designed for the audio band. The peak of the muzzle blast lasts about 5 milliseconds, which will contain about 200 samples using a standard sound card. That is plenty.

You'd need more channels. But read the fine print when shopping, many USB sound cards can output six channels or so but may only have two input channels.

Its hard to record hi spl without clipping the mic capsule. You definitely need acoustic attenuation before the capsule. Eletrical attenuation on the output of the mic just turns down the clipped signal from the element. I'd say 4ft is too close. You're going to get

After thinking dynamic microphone so far I dug up this. I don't think you will need any other amplifier.

There are also some speakers you can use, or many speakers of 32 ohm or 100 ohm types. They need a baffle of sorts.

greg

Dynamic mikes can saturate quickly, big time. BTDT.

ohm types.

This is actually a good idea. Maybe one of those piezo tweeters. Probably in this application even a simple ceramic capacitor could suffice as a sensing device.

Problem with all that sound attenuation material is that rot or mold can set in quickly if this stuff is used outdoors.

I'm finding the initial peak is from 100usec to 800usec long, from 0 to peak to 0. I don't think I could ever be sure I caught the peak. What do you think? Mike

Possible - depends on barrel length and charge design. If you record with a laptop, you can be sure you have the peak - otherwise you are pretty much in the lap of the gods.

You do know this work has all been done in great depth - do you really need to repeat it for yourself?.