I was asked in another thread if I'd make a video on how to buil inexpensive harp mics (aka. "i-mics"). This is the first installment in a series I'll post here about this topic. This one focuses on mic element choices and other components. The next will show how to drill and assemble the shell, solder the compnents, and assemble the mic. I'll do some sound tests of my i-mics in a third video.
The other video's will follow in the next couple of days.
Inexpensive High-Z Ceramic and Crystal elements can be bought at Mouser Electronics. Search for "Kobitone" brand, and look for the elements that have 50kohm impedance or greater.
A great place for cheap surplus electronic components is the electronics goldmine. This is a local Phoenix (scottsdale) based company, so I shop them a lot.
A great source of harder to find audio electronics components is Small Bear. This is a small operation based in New York that is largely supports the DIY elctronics community.
I've bought components from various other online retailers, but these have been my mainstays, and I'll vouch that you'll have a good experience shopping with them.
Great video, Im really looking forward to the complete series and making one of my own! After I make one itll be time to pick up some sort of amp. Perhaps pignose or something in the $100ish range.
Thanks for the video, and the follow-ups to come. The time you take for detailed explanation and information that a non-electronics guy wants to know is helpful. I've been curious about mic building, but have no business doing it. This sort of mic and tutorial is about my speed, and will help me get into it without losing an eye or whatnot.
Hey Isaacullah, I have a ceramic mic I bought off ebay which was originally sold in the 60s/70s as a kit which you made up. It work fine when I bought it but I took it apart and noticed that the wires were connected to the element by little clips. I decide to solder the wires on and again it worked fine. I picked it up the other day to play it and it made a very loud humming noise when I plugged it into the amp. I took it apart but couldn't see anything obviously wrong. I noticed that the hum got less loud when I touched certain parts of the metal chassis. I'm guessing this is some kind of earthing issue. Any ideas how to fix this?
Oisin, it sounds to me like a hard short. Somehow the "hot" wire it touching ground. If the shell is grounded (probably is), then it could be an exposed wire touching the shell, or potential the "hot" terminal of the pot has bent and is touching the shell. Crack that sucker open and look for any exposed copper in the wires. Use electrical tape to insulate them...
@Lumpy: that's a great tip! I'll use that from now on. This particular shell was very resiliant, so I didn't squash it too much, but I've squashed an aluminum shell before. I was able to unbend it, but it's better to not bend it in the first place.
@jonsparrow: Very cool stuff!!! Looks really nice.
isaacullah- Awesome videos Thanks! One more favor.... Any specific (as in Part #'s etc) suggestions for a few types of elements and pots that will work good for harp mics. I was overwhelmed by the number and types of elements available. None seemed too expensive, but So many!! Maybe you could tell us something like...ok, for a good vintage sounding dynamic element that would fit in a saltshaker size housing, buy model xyz123 from Acme Elements, for a crystal element get part # abc123, etc. Please give us an "Complete Idiot's guide to buying Mic Elements and pots" So much appreciated!
Thanks for this series of vids. I've read about "i-mics" for a year or 2, and since I have some basic soldering skills, I'd like to give making one a try. I'll sit back and see what elements you guys use, and hopefully I'll learn something. Most ppl could wire up a mic, but as I understand it, you need the right element to make it worthwhile. I just want something that I can use with a small practice amp.
Hey SMaxwell: The only High-Z element I've bought came from this guy: http://shop.ebay.com/merchant/surplusradioequipment?_npmv=3. He doesn't have the kind I bought enymore, but he does have some shure elements for 12 bucks. The Kobitone elements in these search results should be good, but I have not personally tried any of them. I mainly get my elements from salvage electronics these days. I head down to the thrift shops once a month and rummage through the electronics sections to see if I can find anything. I also periodically look at surplus and salvage electonics dealers on the web. Most of the time there's nothing, but every once and a while you find a deal!
Isaac...you were bang on the mark. It was a little tiny piece of copper wire from the hot terminal was touching the main part of the element. I cut it off and it now sounds great. Thanks for your help.
Ok- Thanks for the link to the elements, I'm gonna order a couple of them to play around with. Can you give us some similar parameters for pots? I know there was some discussion on the Honeytone thread about going with pots somewhere between 100ohms and 1kohm but what about "tolerance," "power rating," "voltage rating" etc. Thanks again, looking forward to the next vid.
(Some of those pots on mouser are $20 - $40 ! wow, whats the advantage? Can I go with one of the $1.50 ones and be ok?)
Last Edited by on Apr 11, 2009 10:57 AM
SMaxwell: Yeah, those freakishly expensive pots are either for audiophiles who can "hear" a difference, or for things like high voltage or super precision use. You can get away with cheaper pots. The most expensive one I've ever bought was in the $6 range, and that was becuase I needed one small enough to fit in a specific space. $1.50 to $2 is about right. You should use a pot with short shaft (~10mm in height), otherwise you'll be sawing it off with a hacksaw if you want the knob to sit flush with the shell. For mics, the more compact the pot the better. There's not a lot of space to play with. Small shaft diameters are good too.
There are two types of tapers: linear and "audio". ausio taper is also sometimes called "log" taper. A linear taper pot's resitance increases linearly (duh) as you rotate the sweeper. An audio taper pot's resitance increases as a log function (multiples of 10). An audio pot gives more control across the entire sweep, so you can fine tailor the attenuation at the low end of volume, whereas with a linear pot, you'llbe pretty much dead quiet around halfway through the sweep. In practice, it doesn;t matter much for volume controls, but most people have a preference one way or the other. I use both. Taper style matters more for other types of controls (ie. in distorion or echo pedals) As for the value, you'll need to use one that's appropriate for the output impedance of your element. In general, you'll want a pot that has a max resitance that is higher than the output impedance of your element. If you have a low-z element (typically 300-600 ohms), then a 1k or 10k pot is cool. If you have a high-z element (usually around 50kohms), then a 100k or 500k is cool. If you have a very hot element (maybe 250koms), then you'll want a large pot (500k, 1Mohm, maybe even 10Mohm). For use as a volume control on a mic, power rating and voltage rateing don't matter. Your sending millivolts and milliwatts at it, so it'll be fine. Tolerance refers to how closely individual elements will match the specs in the datasheet. Low tolerance elements can be off by several Kohm. In general 5% tolerance is cool. Try to get pots that have a resistive plastic sweeper. These will last longer and not go all scratchy. The ones with carbon sweepers are crappy.
no problem, it would be nice though if you can get the camera more up-close as in your first video.... in the 2nd video some of things you are doing are very hard to see. (either way, it's greatly appreciated)
Yeah, it was too hard to try to hold the camera and do the work with both hands at the same time. I was trying to get a good angle on it by putting it "on the level" of the work by stacking some books on the desk, but it did not turn out the way I'd hoped. I'll dig out my tripod from the closet, and see if I can set it up to look down on the work from "my" point of view for the next vid. I'll solder on the element, and then assemble the whole shebang. We'll see how much time that takes, but I'd like to play all the mics thru the same amp with the same settings, so you can hear what the various elements and body types would bring to the table when making your own mic. ---------- -------------- The magnificent YouTube channel of the internet user known as "isaacullah"
Allright you harp lovin' fools! I had a good block of time this afternoon so I finished up my series on how to build your own inexpensive harp mics... First is this video showing how to solder on the element from a better viewpoint than the other soldering video:
Next is this video showing how to put it all together ("guts" into the shell), and explaining about gaskets, why they are important, and hw to make your own inexpensive ones:
Finally this one is me playing all my DIY mics thru my pignose 7-100 one right after the another and leaving the pignose at the same settign (for the most part):
If you've enjoyed these and/or found them useful, let me know. There's other stuff I can talk about. For example, I can make a vid about how to turn a mini mag light into a mic, and I cna make vids about building your own amps (solid state only), effects (mostly overdrives), mixers, etc...
Thanks for the videos, Isaac. They're inspiring me to shop for the tools and parts and begin building a mic. I'm interested in seeing another video if you were to build a mic inside a smaller/narrower shell such as a former flashlight, too. Amp videos would be welcome also, to build the infamous 'cigarette box'/cigar box amp or Pignose equivalent (plug in or battery power) would be some good education. The extra time you take to explain what you're doing, and why, and identify component features or differences has been a big help. Keep 'em coming as time or feedback permits.
I will check out your latest videos as soon as I get a chance. Im very excited to get to work on one of my own. My vote would be to DIY videos on noisey cricket amp. Ive been looking at the specs & stuff to do one but it would be great help to have the same type of visual. Thanks for the videos!
Hey guys, thanks for the great feedback! Sounds like folks want me to make a vid on the mag light mic and the lm386 amp (aka: smokey, noisy cricket, ruby, little gem). As it turns out, i've got the parts to do both! I'm off to the big archaeology conference next week, and currently getting my paper ready for it, so it will be a couple of weeks until I can get a bit of free time to do those. I'll start a new thread and post the videos here when I do them!
Hi Isaac you mentioned in one of the videos that the flashlight mic uses a phone 'earbud'. What do you actually mean by that? Do you mean the ear piece or that you dismantled a handsfree kit and took the mic out of it? Also , any chance of posting a wiring diagram for clarity, I think you said that the pot is in parallel with element with the jack between one end of the pot and the wiper, but I may have misunderstood.
@ lumpy: Yeah, I mean that I took the earpiece from a cellphone "handsfree" earbud, and used it. Any speaker can be used as a mic--speakers work the same way dynamic elements do. Usually you'll have big impedance matching issues using speakers as mics becasue they normally have impedances of 2-8 ohms, where "low-z" dynamic mic elements have impedances of 300-500 ohms. For some reason, the cell phone ear pud element I used has a much higher impdeance than do other such earbud speakers, and hasa frequency response that works really well for harp. I'll make a vid on the subject in the near future, showing the wiring, and being more complete about it.
Hey Isaac! I tried building my own i-mic this weekend to absolutely no success. I'm an electrician, so I'm pretty confident about my wiring methods and soldered connections. I've even ran continuity and Resistance tests with my Multi-meter confirming everything "should" work right. However when I plug the mic in, I get nothing. I got i-mic instructions off www.planetharmonica and noticed that I did not actually have a mic capsule, but a mic element. What's the difference, and does it make a difference building a mic? Here's a link of exactly what I bought:
I tried to build one using the same type element and it didn't work either. I harvested on from a phone and ended up using the ear piece instead which actually worked ok. But in the description I think I see the reason - 4 to 10V required. It looks like it needs phamtom power.
In case Issac is busy - you are probably right scott, that type needs power - when I first started fooling with this stuff, I would go to the dollar store and buy up the karaoke mics, rip 'em apart and away ya go. The other options I tried was getting clones (just the replacement cartridge) of the shure 58 from apex - up here it cost about $7 but had pretty good sound, a bit warmer than my Green Bullet (non vintage) if I can figure out how to get my GB volume control on it - it would be my go to mic.
Last Edited by on Apr 20, 2009 3:20 PM
Yes, Electret mics need a power source. Don't confuse this with phantom power - not the same thing. In the end though, an electret element will ONLY be good for very clean acoustic playing. They don't break up well.
For a harp mic you want a crystal or dynamic element. Crystals create electrical current when they're flexed, dynamic elements create electrical current by means of a magnet moving past a coil. Dynamic elements are virtually identical to a speaker - its just instead of applying a current to the coil to move speaker cone, we move the "speaker cone", called a "diaphragm" when it is a mic, and it generates the electrical signal that is sent to the amp. Crystals are always high impedance; dynamic mics can be low, medium or high and may need some sort of transformer to ensure a high impedance output which is what a guitar/harp amp expects.
Thanks Greg! Wow this forumn is turning into a celebrity site. Buddha, Jason, and now Greg Heumann!
So I had already split my time of learning/woodshedding the instrument to tweak and customize them. Now I've gotta divide that time into thirds to start getting into building mics and moding amps.
Maybe being good at a couple things will satisfy not being great at one.
Issac, I just got back from a week of of town and saw the last three videos, thanks for creating them, I have the confidence to try my hand at making one now. While I was out of town I hit up some thrift stores an picked up some cheap Mics (karoke I think)I can steal elements out of and experiment with before I order a good element. Thanks! Was very helpful!
Watching Isaac's videos got me to thinking about the Hohner Hoodoo Hand. How the heck does that thing work? Has anybody on the forum used one? I like the idea of a fairly inexpensive wireless system if it performed well, but I haven't seen any posts regarding them.
i made my mic and it work ok. i used a switch i found in work i took the ear peice from a wireless phone and bought a 1/4'' jack .. isaac can you tell me the numbers of the parts that are needed and from who would i buy this from thanks fred
Last Edited by on Apr 27, 2009 8:02 AM
Hey guys. Sorry, I've been out of town at the annual archaeologists meeting in Atlanta... I'm glad you are all digging the vids! I'll try answer the questions you've asked in order:
@Preston: Yeah, Greg answered your question there (aside: Thanks for jumping in on that Greg! It's GREAT to know you're on this forum now!). You need to have a power source for those kind of mics. I've got a design for one, but I haven't built it yet. My plan os to have a little "belt pack" with the battery, circuitry, volume control, and 1/4 jack, and then have a thin wire going from the belt pack to a small electret element on a ring (similar to the Hoodoo Hand, and others). But I haven't doen that yet. i'll let you all know how it goes. To do the "this link" stuff, you just have to look up "how make a hyper link in HTML" on google. look for a bit of code that has "a href" in it. I can't complete the code in this post or it will make an actual link out of it! :)
@jawbone: Great tip!!! I'll have to look in to the apex sm58 clone elements. That's something I've been trying to find for a while!
@SMaxwell: Alright man! i just LOVE rummaging through the electronics aisle at teh Goodwill! It's one of my favorite wys to waste time! :) Good luck on your mic building!
@bluzlvr: See my comment to Preston about the "belt pack" mic. I've also been looking into ways of cheaply going wireless. I've investigated fm transmitter/reciver kits, Bluetooth, and 900Mhz telephones. Bluletooth sufferes from latencey (lag time), so it's not good enough (yet) for real-time audio. FM transmitter/reciever kits are cheap, but can be "hacked" by radio sation interference, and have lowish audio quality. Hacking a 900Mhz phone has potential, but I have yet to get my hands on one that I can destroy without my wife becoming very very angry with me. I've seen one website where a dude hacks some two way radios to wore asa wireless guitar rig. He says it works but that it is "lo-fi". Lo-fi can be good or bad depending on your needs, but again, I only have the radios i use for field work, and I'm unwilling to bust 'em up for this kind of experiment. One day I'll figure something out (likely after another Goodwill bonanza find) and let you all know what I discover.
@Fredrider51: Sounds like you got most of the process down! I know that the earbud I used was from an old Nokia phone I used to have, but I don't remember the model number. I'll show how I did it in a video about "maglite" mics I'll make in the near future.
Issac - I'll find the old label that was on the package - it's in my shop - it probably wasn't the 58 clone, probably further down the price range. I'll post a complete picture when I get a minute. I have always wanted to do that belt pack thing but schematics confuse the heck out of me and when they start showing transformers, wiffle rods and senserdwivels in diagrams style I put my hands back in my pockets and sigh.....
PS - Thanx for posting those videos - I haven't watched them yet as I'm on dialup and have to wait til I'm someplace with high speed. ---------- If it ain't got harp - it ain't really blues!!!!
Last Edited by on Apr 27, 2009 6:05 PM
How can I put a photo up? Do I have to use photobucket? I'm on dialup and my computer seems reeeeeaaaaally slow. It won't upload. Any help? ---------- If it ain't got harp - it ain't really blues!!!!
I have my own webspace throught he university that I use to host my images, but you'll probably have to use photobucket or something like that. Then type the link to the image using the html tag for linked images (search google for example code. It should have the words 'img src' in it. I'd post an example, but it would be read as code by the forum, and you'd see an image instead of the code!) ---------- -------------- The magnificent YouTube channel of the internet user known as "isaacullah"
Hey Issac - Thanx for posting my pics - I had the instructions all typed out but the computer timed out and dumped it!! If any one is interested I'll try again - stupid dialup!!! The only other thing you need that is not shown is some carpet underlay to wrap around the cartridge to hold it snug when you pressfit it into the cap. I'll post more info later. ---------- If it ain't got harp - it ain't really blues!!!!
Last Edited by on Apr 29, 2009 1:58 PM
