Hi ! I have just bought a behringer ECM8000 mic to measure my new DIY speaker. But i just realised that a mic preamp is needed to connect the mic to my pc for making measurements. I am still a student and do not have enough funds for buying a commercial preamp for the mic as i have almost emptied by pockets building the DIY speaker. After searching i found INA163 chip by TI. Is the mic preamp schematic in the datasheet suitable for use with the ECM8000 mic that i have bought ?
That schematic leaves out the power supply for the chip and the phantom supply, and not being an EE there might be some practical concerns as well.
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These are the two typical solutions:
rolls mp13 - Google Product Search
xenyx 802 - Google Product Search
The cheapest way to make a mic and preamp is probably to forget about the ECM-8000 and buy a panasonic capsule and make a Wallin preamp (or look at the one on Elliot Sound pages)
You can just use an electret capsule connected to the mic input, but this tends to be quite noisy on most computers. Probably doesn't matter for measuring, though.
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These are the two typical solutions:
rolls mp13 - Google Product Search
xenyx 802 - Google Product Search
The cheapest way to make a mic and preamp is probably to forget about the ECM-8000 and buy a panasonic capsule and make a Wallin preamp (or look at the one on Elliot Sound pages)
You can just use an electret capsule connected to the mic input, but this tends to be quite noisy on most computers. Probably doesn't matter for measuring, though.
Why not support one of our advertisers? Seventh Circle Audio has an entry level ($79) kit that is based on a great circuit. You could not put the bag of parts together for that. No commercial interest, goes without saying.
This is exactly what you need and much more. Do It Yourself, like me. I had the same need like you before 3 years. The cost it is around 30Euro (included the chassis). This mic. preamplifier except that it offers the correct phantom power for the ECM8000, with the addition of a simple switch can accept as well dynamic microphones and offers a stereo output; you can use it as well as mono via the pan-pot (balance) taking thus the signal either from the left or right output. I have the full documentation of construction, as well its performance in: http://www.eal.gr/MICROPHONE%20PREAMPLIFIER.htm
It is fully tested for use with the Audua inc. Speaker Workshop free software.
An externally hosted image should be here but it was not working when we last tested it.
Regs
Fotios
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Another 2 shots with the ECM8000 clamped on the input XLR. You can see as well the details of front panel.
In the 3rd picture, you can see (or anyone who is interested) my own version of the jig-box which is needed for use with the Speaker Workshop. It is based on the Carlo Negri design.
There is as well a compensation file for the ECM8000 to put in your measuring software in the mic. calibration menu.
In the 3rd picture, you can see (or anyone who is interested) my own version of the jig-box which is needed for use with the Speaker Workshop. It is based on the Carlo Negri design.
There is as well a compensation file for the ECM8000 to put in your measuring software in the mic. calibration menu.
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Wow Fotios You are a genius. Thanks. This circuit has so many components comapared to the INA163 chip circuit. Btw do i need 50VA transformer for this mic preamp ? Will a 6VA one do ( I have one lying around)?
Thanks friend, you are very polite as usually; i know very well (as well many other members) that such type circuits are child's-play for you. 😉
Fotios
Thanks Buzzy for you kind words. Me, i am not the genius here. There are most clever designers from me in DiyAudio forum. Moreover the smart point of this circuit is the input sensitivity pot VR5 between the two input buffers (U1A-U1B). This topology is ready offered in the National Semiconductor LINEAR 1 databook (see in LM833 typical applications) but with a fixed resistor instead the pot.
As for the 6VA x-former i think it is of small power to supply the circuit. As well, the 50VA that i use it is surplus. But it costs only 8 euro, and it is Greek made. I think there are enough encapsulated toroids of the half power which costs 10 euro!
You can build the circuit as is, or you can omit some things like the pan-pot to get a mono output. OTOH what is the profit? A simple 2X100KA pot it costs around 3 euro. What it makes sense, it is to you keep the supply rails at +/-18Vdc to ensure that you will have the same performance presented in the plots.
Please inform me: which software are you using for measuring your speakers? Your sound card?
Fotios
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