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Project Help and Ideas » Project Audio Signal debugger to the computer

February 23, 2010
by luisgarciaalanis
luisgarciaalanis's Avatar

This might be a bit complicated, but I was wondering if the kit could be used to analize signals from a guitar or from the different stages of an guitar amp, and send the data to the computer to be analized and displayed as a wave form.

The idea behind this came to me because I am trying to build a vacuum tube guitar amp. It would be nice to send a signal to the amp and then see it on its different stages, how it gets amplified, distorted so on.

So I have a few questions regarding the Kit part of the project alone: 1) How can the microcontroller be used to convert a signal (voltage change?) to digital? in other words how can I use the Microcontroller to read the signal? 2) How can I do this if what we are reading (tube amps) ar high voltage? some amps are 600V DC, I know there are probes that will x/10 the signal, but still 60VDC might be too much. 3) can the microcontroller read AC signals?

I know audio frequenzies are low for example the A note is 440 hz if I remember correctly, however there are noise freqs on the signal I assume.

Thanks Luis

March 05, 2010
by nalle
nalle's Avatar

Hey Luis,

Nice to see someone else on here that is interested music electronics (if you ask me the vacum tube is THE coolest electronic component EVER!) I recently completed my own tube amp. (cloned a Marshall Plexi model from 1967, I'm a fan of AC/DC and it complitely nails that tone. :)..50W is loud as hell!.....which is nice.) From my experience working with amps you should probably get a signal generator (even a software based free one will do, and a decent oscilloscope.....for the plate voltage measurements always use a multimeter.....always! even if you are checking for 50/60Hz hum. An oscilloscope is useful for the signal path checks and is usefull when looking at the distortion characteristics if you make your amp to have distortion. A really nusefull poject for the MCU in the nedkit would be a bias current meter that works by measuring the voltage across a 1 ohm resistor, 200mV would be quite a high reading across the resistor so the MCU shouldnt get fried if something doesn't go terribly wrong. BTW I got my kit today......there will be no sleeping tonight :)

May I add: proud to be a n00b ;)

March 09, 2010
by norby31
norby31's Avatar

Ok--if you look at the code for the temp probe that shows how to read analog into the uC. What I need help with is outputting a nice signal from the chip. I have processed the guitar sig but I need to get that binary into analog. I made a 4bit summing dac but it sucked.

March 09, 2010
by hevans
(NerdKits Staff)

hevans's Avatar

Hi norby31,

I think you already found it, but I'm mentioning it here for others who might stumble onto this thread. The folks on this pwm for dac thread have made quite a bit of headway on getting an analog output from the microcontroller using PWM and a little bit of analog filtering.

Humberto

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