I have bought a kit to build an LM386 based amp [bitsbox... I order at at lunchtime on Wednesday and it arrived at lunchtime on Thursday by royal mail] Just got to find time to build it. I am also thinking about a mic, but am confused about elements.
There have been lots of threads about building microphones, but what elements can be used? I have noticed the following types, but am unsure what sort to look for to make a mic
Crystal Dynamic condenser electret
Hi-Z, Lo-Z I'm sure there are many others. bit I am thinking about picking up a cheap mic and butchering it to make a bullet type mic as others have done. but what should I lookout for. [cheap remember, they don't call me tightwad for nothing]
Lumpy, they do three good replacement mic elements at Maplin for under £5.00. They are 600 ohm dynamic. I got one yesterday and it is good. I'm currently building another mic but I'm keeping it secret at the moment because when you see it you'll be amazed by how it looks, how little it cost to make, and how good it will sound.
You can see Maplins mic capsules here; http://www.maplin.co.uk/Search.aspx?criteria=mic&source=15
@lumpy: 1) good on ya for getting the 386 kit. I'm sure you will be happy with it. They make really good practice amps. 2) Mic elements. It's not worth it, IMO to search for "new" Crystal/Ceramic elements. Usually the quality of brand new crystal/ceramic elements is not very good, and the sound will be tinny. IMO if this is the way you want to go, you have to go vintage, or at the very least, brand name. Some people swear by crystal or ceramic elements, especially "hot" (very high Z) vintage ones. these people usually are going from this hihg Z element straight into an amp. They use the High Z output of these elements to overdrive the input of their amps to get dirty tone. Condensers and electrets will require an outside source of power (phantom power), so as a beginner, just forget about them. (some electret cartritges are imbued with a permanent charge usign static electricity on one of the element plates, and thus do not require phantom power, but still, as a a beginner, I wouldn't bother). That leaves dynamic. Yes, this is where I would start if I were you, especially with the lm386 amp you are building. Get a nice quality dynamic element. This does not always equate with "expensive", mind you. If tooka's element is a good one, then I'd start with that. Otherwise look for something in the $30 (pound 20) range. Of course brand recognition will help a bit (eg. shure, apex, GLS, audio technica, etc.), but you can get very lucky with "off brand" mics sometimes. elements from tape recorder mics often sound really great, for example. There is a $10 radio shack brand tape recorder mic that sounds really good. These will almost always be low Z. They will need a line transformer if you want them to work like a high Z mic (ie. to overdrive the input of an amp directly). With solid state amps, you usually do not need this. Go straight in, or through effects and then in, and crank the gain until you find your sound. ---------- ------------------ The magnificent YouTube channel of the internet user known as "isaacullah"
@Wheezer. You beat me to it. I've been playing around with a deodorant bottle. If you look for a Unilever one they come in solid black with a silver top.
I've been collecting the balls inside for a while now, haven't a clue what to do with them yet but I'm working on it.
However, the containers are perfect for our use and the dimensions work out just right for installing the mic insert.
I'm currently making one using just the cap this time and the ball grill from a very cheap £1 shop harp. I don't need a volume control. I reckon in total it will cost me no more than £5. It feels good in the hands and has a very nice tone. I'll post a pic when done.
I was interested to hear what you said about the impedance converter. Isn't 600 ohms ideal for a small MicroCube amp? Mine sounds good but if it would be better I'll look out for a converter.
I'm pleased to have met another resourceful blues spirit. I try and make anything I can. I hate being dependant on stores or other people especially dentists, but I've even done my own dental work in the past too.
When the big day of Armageddon comes it will be the resourceful people who can make things that will survive. ----------
Hi Tooka, The impedence converter will raise the output from your Low Z mic. and give you a lot more volume.
One thing I found out (by accident) is that you can alter the tone characteristics of the mic. by filling the void in the bottom of the container with something like cotton wool. The more I fill the empty space the less bass feedback (which was a problem when I first built the mic). The way the mic. void is filled now gives me plenty of headroom on the amp tone controls
"I've been collecting the balls inside for a while now, haven't a clue what to do with them yet but I'm working on it."
This statement is so true of so much to do with harmonica, I don't even know what else to say! Yes, perhaps t2, in the context of his post, didn't actually mean it the way I'm taking it, but I think he somehow did subconsciously. I do believe he has come up with a new MBH motto! ;)
Yeah, there's something odd about someone who collects the balls from roll-on deodorant bottles but I just can't help it, I gotta have them and I want more.
I'm glad it tickles you isaacullah. Maybe it does have a deep seated psychological meaning for all of harpkind but I just want to appeal to everyone who uses roll-on deodorant, SEND ME YOUR BALLS, but not if you are outside the EU because I don't want anymore of that British Customs hassle which I'll explain in a new thread later.
I've built the LM386 amp and it is very quiet. It is powered OK by my mp3 player but I can't hear anything from my mic. Comparing the noisy cricket diagram to my diagram they are quite different. Mine doesn't have the transistor MPF102. i think I'll have to buy some more components and rebuild it more like the noisy cricket.
Just guessing and I haven't seen the circuit but maybe that transistor is part of a pre-amplifier stage in the cricket. That would explain the low volume from the mic. ----------
tooka is right about that. You CAN make an lm386 amp loud enough WITHOUT a preamp section, but you'd have to have set the gain right to do so. Check the schematic of the little gem out, and compare it to the ruby amp which is more similar to the noisy cricket. In the little gem, the lm386's gain is allowed to vary more becasue the gain control pot value is bigger (5k) than that in the Ruby (and noisy cricket) which is only 1k.
Here's a quote from the Ruby page: "Pre-set Gain Ceiling Use a 1k, 2k, or 5k trimmer in place of the Gain pot. This will allow a pre-set for the amount of gain and distortion over the Volume pot travel."
So check the value of the pot that came with your kit. If it is only 1k or 2k, that means that the gain will be capped fairly low. Your two options are 1) to build a simple 1 transistor preamp (ie using a FET like the MPF102 or J201), or 2) by getting a higher value pot (ie 5k or 7k) to replace the 1k or 2k pot that came with your kit. ---------- ------------------ The magnificent YouTube channel of the internet user known as "isaacullah"
Last Edited by on Jan 24, 2010 4:26 PM
Cheers Isaac, I did try it with my echo pedal and it made no difference. I have looked closer at the diagrams and notice that there is a difference [as well as different value components] in that one has the volume pot on leg 3 of the chip and the other on leg 2. When I get moe time I will rebuild it. meantime I am building the Lumpophone [mic].
I haven't done anymore on the amplifier, but have virtually completed the Lumpophone microphone. there's a demo on youtube
I built it from an old kitchen waste pipe fitting, a piece of a grill from an old PC and a piece of plywood. The electronics are from maplins, a 600ohm dynamic element and a 1/4 inch jack socket.
Now, that wasn't a waste of time was it? It didn't drain your resources. It didn't drive you round the bend did it? Whatsmore, it sounds pretty good. It sounds quite Lumpophonic. ----------
