EEVblog #602 - Introduction to Microphones - Page 1
Forum section: electronics / general

author: EEVblog
author_rank: Unknown
timestamp: April 12, 2014, 04:39:12 am
content: In the first of a series of videos tutorials on microphones, Doug Ford, former head designer at Rode Microphones explains the basics of how microphones work, the different types - carbon, dynamic, ribbon, condensor/electret, and how the omnidirectional pattern works.Also, the internal construction of a high end measurement microphone.

author: DutchGert
author_rank: Frequent Contributor
timestamp: April 12, 2014, 10:44:47 am
content: Nice one, this was a topic that I litterly knew nothing about until now. Thx!

author: woox2k
author_rank: Regular Contributor
timestamp: April 12, 2014, 12:02:41 pm
content: Yes, finally some audio stuff.Looking forwards for follow-up videos to take this even further, this one was fairly detailed but got cut short in the end.

author: lewis
author_rank: Frequent Contributor
timestamp: April 12, 2014, 12:07:09 pm
content: Woo hoo! Doug's back!

author: EEVblog
author_rank: Unknown
timestamp: April 12, 2014, 12:14:22 pm
content: Quote from: woox2k on April 12, 2014, 12:02:41 pmYeah, unfortunately there wasn't a huge amount of structure to the whole shoot, being very off-the-cuff and jumping over the place. Going to be hard to edit into sensible sections that flow.But in the end it'll be essentially a big dump of info.

author: Sionyn
author_rank: Frequent Contributor
timestamp: April 12, 2014, 01:26:48 pm
content: loved this glad Douglas has shown his head again (more please) especially his beastly power supply

author: EEVblog
author_rank: Unknown
timestamp: April 12, 2014, 01:50:23 pm
content: Quote from: Sionyn on April 12, 2014, 01:26:48 pmI'll be visiting his new lab shortly to check out what he calls "The Death Star". No, not a power supply, something a lot more exotic...

author: David Aurora
author_rank: Frequent Contributor
timestamp: April 12, 2014, 02:05:35 pm
content: Definitely looking forward to more, great stuff.I don't mean to bust your balls here Dave (seriously, I love your work), but as a recording engineer I gotta admit I got a laugh out of seeing you walk into mentioning/suspecting audiophoolery a few times there haha. I see it on the forum a bit, where if anyone seems to mention the possibility of higher fidelity than an op amp stage on a coin cell they're assumed to be snake oil buying, magic rock placing, $5000 power cord using weirdos. Was really nice to hear Doug talk as a respectable authority on the matter and point out that high quality audio really is a complex topic, and not necessarily all bullshit. I'm really interested to see where the future videos go, both of you are great at explaining things but you also seem quite different in the angle you're coming from so I think it's going to make for some killer videos.

author: delmadord
author_rank: Regular Contributor
timestamp: April 12, 2014, 07:55:11 pm
content: Yeah our almighty Dave looks like he is actually learnig instead of teachnig us..I LIKE IT

author: hi-Z
author_rank: Newbie
timestamp: April 12, 2014, 09:39:47 pm
content: Fascinating subject, loved it.I'm surprised nobody mentioned anything about piezoelectric elements. That's the good stuff.

author: dentaku
author_rank: Frequent Contributor
timestamp: April 12, 2014, 10:17:44 pm
content: It's great to see Dave learning about stuff from a field of technology he's not very familiar with.Sometime it would be great to see a video about and electronic instrument of some sort, beyond Sagan's Yamaha keyboard. Modular (mostly analog) synths are very interesting and so are effects pedals which are very similar. Maybe you could do a teardown of one of Fran Blanches audio effects boxes if someone is willing to lend you one.I'm more interested in synths and their VOCs, VCAs, VCFs, LFOs etc. than guitar pedals though.

author: don.r
author_rank: Frequent Contributor
timestamp: April 13, 2014, 03:27:11 am
content: I wonder how tubes (valves) microphone?

author: calexanian
author_rank: Super Contributor
timestamp: April 13, 2014, 03:49:31 am
content: Quote from: don.r on April 13, 2014, 03:27:11 amAre you referring to micro phonics in a tube? Well, Vibrations wiggling a grid rather than a diaphragm. Although a grid can be seen as a diaphragm with slots cut in it. There are two modes of transduction. One is direct action of altering plate current through physical vibration of the grid (The most common) and capacitive changes in the grid with the basic same effect. There have actually been purpose built microphone tubes for specific frequencies and measurements.

author: sdscotto
author_rank: Contributor
timestamp: April 13, 2014, 05:49:17 am
content: I got a real kick out of all the metric this and metric that followed by "this is a 1/2 inch reference mic"Can't wait to learn more, in metric of course!

author: 99tito99
author_rank: Regular Contributor
timestamp: April 13, 2014, 06:09:50 am
content: Hey, I'm a Yank and I understand meters and feet!Cheers,Mark********************

author: EEVblog
author_rank: Unknown
timestamp: April 13, 2014, 07:28:04 am
content: Quote from: David Aurora on April 12, 2014, 02:05:35 pmBecause that's were the laughs are, it's called taking the piss.No, I do not assume everyone who wants good audio performance is an audiophool. Any indication you have of that is incorrect and of your own making.QuoteDoug thinks exactly the same way about audiophools as I do.But because I've done a video poking fun at audiophools, and love to poke fun constantly, I get incorrectly pigeon holed as thinking that anyone who listens to music and asks a question is an audiophool.

author: DrGeoff
author_rank: Frequent Contributor
timestamp: April 13, 2014, 08:12:36 am
content: Was Doug involved in the design of the original NT-1?That's one of the quietest condensor mics ever made and still very handy for recording some vocalists.BTW, some dynamic mics sound much better when terminated with a particular load impedance. For example, the SM57 is great into a 600 ohm load. A lot to do with the termination of the internal transformer to stop ringing.

author: EEVblog
author_rank: Unknown
timestamp: April 13, 2014, 08:15:30 am
content: Quote from: DrGeoff on April 13, 2014, 08:12:36 amYes, and he goes into the circuit design in a future video, and why it is so quiet.

author: G7PSK
author_rank: Super Contributor
timestamp: April 13, 2014, 08:40:15 am
content: Very interesting on the old carbon microphones, a balanced carbon rod microphone was one of the first electronic things I built (well more electro mechanical really) it was so sensitive that you could hear a fly walking with just a set of high impedance headphones.

author: fcb
author_rank: Super Contributor
timestamp: April 13, 2014, 08:54:54 am
content: Quote from: don.r on April 13, 2014, 03:27:11 amTube mikes - the tube/valve is just the local amplifier/buffer for the pick-up, in place of a FET.

author: SeanB
author_rank: Super Contributor
timestamp: April 13, 2014, 09:26:18 am
content: Microphones are available is various qualities, depending on how much you are willing to pay. Up to a point there is a near linear rise in performance, but if it is gold plated on the outside, and just junk on the inside it is Audiophoolery.Carbon microphones are still in use in intercom systems, as they are pretty insensitive to hum on the supply lines, and survive lightning strikes nearby. I did upgrade a couple though using a spare electret insert and a single PNP germanium transistor along with a bias resistor across BE junction to set operating current into the speaker in class A in an intercom. More sensitive and less noise, but only done as the carbon no longer responded to banging and I could not get a replacement quick, as they were out of stock, and only offered a complete indoor unit at a price. Biggest killer of the carbon microphones are cleaners with spray furniture polish, which builds up a silicone oil coating on the granules.Edit because I suddenly forgot how to spell correctly.

author: David Aurora
author_rank: Frequent Contributor
timestamp: April 13, 2014, 09:45:27 am
content: Quote from: EEVblog on April 13, 2014, 07:28:04 amHaha nah man, I'm not lumping you in the extremist category, that forum reference was in regard to a bunch of threads I've seen (and particularly one dude whose name evades me who always manages to steer high quality audio discussion into how much he hates tubes and people who use them).Don't worry, us studio geeks think exactly the same about the audiophool world

author: don.r
author_rank: Frequent Contributor
timestamp: April 13, 2014, 03:12:29 pm
content: Quote from: fcb on April 13, 2014, 08:54:54 amLOL! Not what I meant. A tube can start to "microphone", i.e. acts like a microphone itself (act like a pickup) and I was curious about the physics involved there.Quote from: calexanian on April 13, 2014, 03:49:31 amThanks. I thought it was the grid acting like a diaphragm.

author: 99tito99
author_rank: Regular Contributor
timestamp: April 13, 2014, 04:18:20 pm
content: Hi Dave: Thanks to Doug and you for the video (and I gather a few more to come). I do not consider myself an audiophile nor an audiophool, but I do like good music reproduced well and I like learning about thing I don't know much about. Cheers, Mark * * *PSWhen I was a kid (12 - 14?) I got hold of a carbon microphone and of course I did not "Plug It In, I Took It Apart." It was a big sucker on a stand, probably from a Ham transmitter. As I recall it contained about a teaspoon of carbon granules that were glossy black and about the size of table salt (~1/3 - 1/2 mm).

author: Bored@Work
author_rank: Super Contributor
timestamp: April 13, 2014, 04:41:31 pm
content: Quote from: 99tito99 on April 13, 2014, 04:18:20 pmWhen I was a boy(TM)we built our own from the carbon rods of old batteries. A bit difficult today with almost only alkaline or rechargeable batteries around.

author: SeanB
author_rank: Super Contributor
timestamp: April 13, 2014, 05:10:50 pm
content: Cheap Chinese batteries are still around, and they still have the carbon rod in them. The regular black Ever Ready battery range here is an example, though those may still be made in South Africa. I have not looked for a while.I used to take D cells and use the carbon rod as a welding rod, it works quite well to do small sheet metal work. You cook it a little in a fire to get the wax out, wind the end with a copper wire for better contact, and use a pencil sharpener to make the other end pointy. made microphones using them and 2 halves of a Minora razor blade ( just think that as a kid I could go into a shop and buy bare razor blades no questions asked, and walk around with a knife as well. Could even buy fireworks and matches, along with cigarettes, but no alcohol) on a wooden block along with an old speaker and some wire and the remaining D cell as power.

author: Richard Head
author_rank: Frequent Contributor
timestamp: April 14, 2014, 10:40:47 am
content: It was a great video. I would like to hear more, and don't get scared of getting too technical. The more the merrier.

author: Richard Crowley
author_rank: Super Contributor
timestamp: April 14, 2014, 03:30:47 pm
content: A Fiat will get you from point A to point B. So why do people buy Ferraris?

author: DrGeoff
author_rank: Frequent Contributor
timestamp: April 14, 2014, 09:28:40 pm
content: Quote from: 3roomlab on April 14, 2014, 03:19:46 pmPut their logo on it.

author: Richard Head
author_rank: Frequent Contributor
timestamp: April 15, 2014, 06:09:28 am
content: A Ferrari is a Fiat!

author: miguelvp
author_rank: Super Contributor
timestamp: April 15, 2014, 06:18:08 am
content: Quote from: Richard Head on April 15, 2014, 06:09:28 amAnd a Lotus is a Proton! I still love mine