using small speaker as a mic...

  • Thread starter Thread starter Roel
  • Start date Start date
Roel

Roel

That SMART guy.
A while ago, a friend found an old mic somewhere, that used a small speaker... The kindof speaker you find in those small radios.

What circuitery is needed in between the speaker and a mic input? I'd like to experiment with it. It had quit a funny distorted sound. Especially thru his tube amps... hehe...
 
A speaker is nothing more than a dynamic mic used in reverse (or the other way round). So you need a mic pre-amp with a bit more gain than usual, no phantom. This is used in small intercoms sometimes.
 
Im not gonna say names, but i had a friend mic his kick drum with a 6X9 car speaker......didnt sound terrible.......
 
I mic'ed my kick with a small headphone speaker. It also didn't sound terrible. And the drum didn't sound good to start with--it's tuned right now, so I wonder what it'd sound like? I should try it again.
 
The newest issue of Tape Op has an article on making a telephone mic. It involves rewiring the speaker of a phone. I am gonna try it this week. I imagine that with some slight modifications to the schematic for the tele. mic, almost any speaker could be used.

You may want to check out the Tape Op article.


Cheers,

Bryan
 
On that phone thing...the article may be in need of some correction:

http://pub55.ezboard.com/ftapeopfrm2.showMessage?topicID=1449.topic


The tapeop board has dicussed the speaker as a mic thing....I cant find it though. I believe it was as simple as wiring the hot to tip and the ground to ground using a quarter inch mono plug.

What I wanted to find though was, there was some discussion on using a tranformer to make it low impedence and there was also some talk about the difference between enclosed and raw speakers....some guys has used an NS-10 right out of the control room!!

I think there was even some talk about which driver to buy...I remember something about a part number and the driver being a good headphone driver that one could obtain for like 2 bucks.

All I know is that some guys really liked it!

If you really want to know....sign up over at:
www.tapeop.com
And ask some of the stuff I'm talking about...they are a good bunch of people over there. Its the only other board I participate much in!;) (although the answers come a little slower)

good luck and if you find out....let us know!

heylow

(BTW...I have nothing to do with Tapeop execpt as a reader and board participant....dont want any panties in bunches!!!;) :D )
 
The one to look for would be a speaker from an old walkie-talkie.
It served as both the speaker and microphone.I guess it just reversed the path when you mash down on the talk button.I bet you could get some cool "old time radio" or telephone effects from one.They might be a little bit more "optimized" for use as a mic...........
 
Actually, I have used the speakers out of the old walkie-talkies already in my cracklebox... I think...

But I remember another pair that came with a headset! Which also has a mic. Which means, I got even more mics than I thought I had! Cool. I'm gonna record a demo with speakers. hehe :rolleyes:

Oh boy. This is gonna lead to alot of wrong ideas. Wait until I tell my lofi-friend that thinks half of the records sound to 'clean'. I'm scared now.
 
I've actually turned several people onto this over the years. I still use this as one of my favorite kick drum mics. The speaker I use & suggest is obtainable from Mouser Electronics, Part# 25SP500. Cost = $5.14. It's a 1.57" Mylar speaker (also suitable for earphones) The impedance is 600 ohms which is fine for low impedance mic inputs & you need no transformer or extra preamping. In fact the signal to your mic inputs will be nearly twice as hot as a typical dynamic mic It's a full range speaker 20-20k but not all that flat. It could also be used for vocals or anything else if you happened to like whatever character it imparted upon it, but it can really be pretty darn good as a kick drum mic. especially with a little ingenuity & some DIY skills. Just on it's own in free air, wired to an XLR jack & held in front of kick drum you can here it's potential in this area for picking up the deepest bass drum tones, but of course you need to put it into a suitable housing & that's where the fun comes in as the response (both tonality & polar pattern) can vary dramatically for better or worse by how you mount & house it, how much you seal or port the back, how deep & what shape of any back cavity. On it's own in free air of course it's a figure 8 pattern (which is actually workable in a kick drum application) & has decent full range response. If you totally enclose the back it will of course be omni directional (no good for kick drum). I've not tried it with the back totally enclosed so I don't know how it sounds that way. The details would be a little tough to describe but after some educated guessing & much trial & error I came up with something that works well enough & gives sort of a hypercardioid like pattern. I housed it in a simple steel electrical outlet box. The kind that takes a single space dual receptacle & has neither a front or back plate (basically just 4 walls/sides) with punch outs. The capsule is shock mounted inside as a side address & a punch out hole is the perfect size for installing an XLR jack while another punch out hole is used for a standard electrical conduit clamp which I use as the mic stand adaptor. To protect the element I put in some fan filter foam & cut front and back screen plates from some metal paint roller screens which easily soldered to the receptacle box. Looks like something out of a 'Mad Max' movie :D but sounds great. Our drummer uses on the kick drum when we play gigs. Total cost approximately $11 - $12 not counting shipping for the speaker. :) I'm sure there are countless other usable DIY housing & mounting designs to come up with that could put this or similar speakers to good use, so have at it . It can be a fun project & the results can (with a little thought & perseverance) be rewarding.

YMMV
-Stephen Simpson-
 
Knowdoubt...

This was indeed the kind of info I was talking about!

Is there any way you could post a pic......or even a rough drawing to kind of use as a guide?

GREAT post!!

heylow
 
Havoc said:
A speaker is nothing more than a dynamic mic used in reverse (or the other way round).
Click to expand...
This is soo cool! I can't wait to do some mixes on my sm-57's!

...well, at least the concept works in one direction. ;)

I actually accidentally discovered this idea as a little kid, messing around way too much with my dad's stuff. I plugged headphones into the mic in of a tape deck and started screaming into the phones. I remember that it had this cool, distant, super low-fi quality to it. It's amazing what you think of as a child when your ideas aren't as shaped by what you're taught to think of as right and wrong.

I'm a crazy mo-fo who likes building shit... Looks like I found my next project!
 
Yeah, the govmint has all our tv and hifi speakers wired up so they can spy on us and hear everything we say. :D
 
Havoc said:
A speaker is nothing more than a dynamic mic used in reverse (or the other way round).
Click to expand...

Hey guys, remember this part from Harvey's famous thread:

"How a "dynamic" mic really works will definitely surprise you (hint: it's NOT just a small speaker in reverse).Well, it has a cone (like a small speaker), a voice coil (like a small speaker), and it sits in a magnetic gap (like a small speaker), so isn't it just a small speaker in reverse? Yes, and no. The operating principle is the same, but the execution is very different. When's the last time you saw a 3/4" speaker that went down to 30 or 40 Hz? Here's how it's done:

The system resonance is chosen for a mid band frequency. By itself, the capsule's response looks something like this:

......./\
....../..\
...../....\
..../......\
.../........\
../..........\
./............\ - just one big resonant peak, with the response falling off rapidly on each side of the peak. Now you can tame that peak by putting in a resonant chamber that's tuned to that peak, which will give you two smaller peaks on either side, like this:

..../\..../\
.../..\../..\
../....\/....\ And if you add two more resonant chambers, tuned for each or those peaks, you wind up looking more like this:

./\../\../\../\
/..\/..\/..\/..\ And if you make the chambers a little more broad band, the response starts to really flatten out:
._..._.._..._
/..\/..\/..\/..\ but remember, it's still a lot like a bunch of tuned coca cola bottles inside there.

Now ya gotta do all of this stuff JUST to get the response usable - never mind about the mic pattern yet!
!
 
heylow said:
Knowdoubt...

This was indeed the kind of info I was talking about!

Is there any way you could post a pic......or even a rough drawing to kind of use as a guide?
Click to expand...

I'll see if I can borrow a digital camera in the next week or so & post a pic.

-Stephen Simpson-
 
You must log in or register to reply here.
Back
Top