Microphones for sound demonstrations - Page 1
Forum section: electronics / projects

author: txphy
author_rank: Newbie
timestamp: January 15, 2015, 10:46:38 pm
content: Hi! Am looking for two microphones to connect to the Rigol DS1052E to display waveforms from a tuning fork or sound generator for speed of sound classroom demonstrations. What specific microphone would work well in this application?Also plan on putting the mics in ziploc baggies and immersing in a water bath to measure speed of sound in water, too. Looking forsimple& inexpensive but reliable- although audiophile high quality is probable overkill. Thanks for your suggestions!!!

author: rx8pilot
author_rank: Super Contributor
timestamp: January 15, 2015, 11:59:10 pm
content: You will need a pre-amp to get a voltage the scope can see.

author: wiss
author_rank: Frequent Contributor
timestamp: January 16, 2015, 12:10:28 am
content: Behringer condensers and a simple opamp based amp/phantom supply.

author: LaurentR
author_rank: Frequent Contributor
timestamp: January 16, 2015, 12:16:09 am
content: Don't know if these fit your budget, but they are nice and easy to use.http://www.adafruit.com/products/1713

author: barry14
author_rank: Regular Contributor
timestamp: January 16, 2015, 01:37:06 am
content: For this application, I have used a Radio Shack sound level meter. They are cheap, battery operated, sensitive and provide an audio output which is easily observed on an oscilloscope. You can pick one up on Ebay for a very low price especially compared to buying a separate miccrophone, providing a preamplifier, connectors, battery holder, etc. They also work well as sound level meters.

author: dannyf
author_rank: Super Contributor
timestamp: January 16, 2015, 02:05:01 am
content: It wouldn't surprise me if there is already an app for that - a smart phone would have all you need right there.

author: AlessandroAU
author_rank: Regular Contributor
timestamp: January 16, 2015, 02:52:02 am
content: Get some of these:http://www.daytonaudio.com/index.php/emm-6-electret-measurement-microphone.htmland build/buy your own phantom power injector:http://sound.westhost.com/project96.htmYou should be able to get away without amplification if you're using a scope

author: LaserSteve
author_rank: Super Contributor
timestamp: January 16, 2015, 05:08:30 am
content: Panasonic WM-61A. Electret cartridge, so it needs bias, but nearly flat to 40Khz. Widely used in home made reference mikes. Amp schematic is also at "Sound.Westhost.com" as mentioned in previous post.If you have budget and a source of phantom power, I'm really happy with my dbx RTA series measurement microphone. I've had really good results tuning line arrays and EQing my church with it. After EQing nine mic channels and four speakers, it paid for itself. I'm not so sure I'd risk submergence, so that is where the WM-61A come inIf you really want to have fun with sound, download "Holm Impulse" and let it sweep your room for Reverb Time, Frequency Response, and Impulse Reflections. Just needs a sound card with a speaker out that works while Mic In is also active, and a speaker for the sound source. It covers a much wider time range then a single scope trace. Think of it as a digital sonic radar with nearly infinite memory depth. It also shows phase vs. frequency which is fun.At Christmas, "Harbinger" mixers with phantom power and a decent preamp were selling for 25$ on sale. They have a high noise floor, but for goofing around and R&D with the RTA mike, they have proven to be very, very useful.Steve

author: Yago
author_rank: Frequent Contributor
timestamp: January 16, 2015, 07:05:11 am
content: This pair might do the job;http://www.thomann.de/gb/the_tbone_em700_stereoset.htmAs said you will need a (two channel) phantom-power pre-amp.http://www.thomann.de/gb/cat.html?gf=preamps&oa=praStay away from "tube" amps, and don't forget the correct leads!The normal trick for cheapo water proofing is put a mic in a condom, obviously don't submerge all the way, but the thin material help not affect the signal as much as a ziploc.Will probably cheer the students up too

author: Pjotr
author_rank: Frequent Contributor
timestamp: January 16, 2015, 11:21:51 am
content: Any battery powered Lavalier electret microphone (clip on microphone) will do. The Rigol scope is sensitive enough to do it without amplifier. If it is for demonstrating the speed of sound, you need two: One as a reference point and one further away. The acoustical origin of a loudspeaker is not well defined and frequency dependant. Although for a rough estimation it will do probably.B.t.w. for the underwater demo you wil need underwater speakers tooFor this look for piezo transducers/elements. Bare piezo elements act as microphones as well.

author: Kalvin
author_rank: Super Contributor
timestamp: January 16, 2015, 12:10:00 pm
content: Quote from: Yago on January 16, 2015, 07:05:11 amIf OP is from USA, OP may get fired if the students are exposed to condoms in the class room. I am not sure whether my previous sentence is a joke or not.

author: txphy
author_rank: Newbie
timestamp: January 16, 2015, 10:06:20 pm
content: Wow, thanks for all the great ideas! Again, my primary goal is to make this asimpleproject that works. Would something like this lapel mic work? It's small and inexpensive, but I think it's unpowered.http://www.amazon.com/gp/product/B005DJOIHE/ref=pd_lpo_sbs_dp_ss_3?pf_rd_p=1944687402&pf_rd_s=lpo-top-stripe-1&pf_rd_t=201&pf_rd_i=B005UJQ2TY&pf_rd_m=ATVPDKIKX0DER&pf_rd_r=049FHKHTJXB4WRHWD0D2Would I have to find a power source for it? How would I connect it up exactly?Here's an alternative that's battery powered:http://www.dx.com/p/boya-by-m1-lapel-microphone-black-324820#.VLmHa9LF84cAnd one more expensive version:http://www.dx.com/p/professional-electret-condenser-stereo-microphone-of-dv-dc-3v-125ma-1632-battery-278233#.VLmKFtLF84cThis is a totally different kind of mic, but I don't think it's powered...would it work?http://www.amazon.com/Audio-Technica-ATR-1100-Unidirectional-Instrument-Microphone/dp/B002HJ61PK/ref=sr_1_2?ie=UTF8&qid=1421426141&sr=8-2&keywords=microphoneAgain, appreciate your advice here!

author: Yago
author_rank: Frequent Contributor
timestamp: January 16, 2015, 10:17:42 pm
content: Quote from: Kalvin on January 16, 2015, 12:10:00 pmNot a joke, it's a well known and used trick in the audio recording industry.Pretty sure a teacher would know their working rules etc.Interesting point though.