Audacity Forum

Thanks guys. I'm using hand-matched .1% 6k8 resistors...

That's for the phantom injection into the microphone line. An mismatch kills the microphone's ability to reject cable generated interference. You don't want to start listening to Terra Nova on your mic amplifier.

Koz

I think the +/- 18V was to be able to achieve 48Vdc (18Vac * 2 * sqrt(2) ~= 51Vdc after rectification). Three volts is right on the edge of not having enough difference for a voltage regulator -- assuming you use a packaged one, and it may have problems with normal mains variations -- it works betw...

Welcome to the design of Dial Tone Multi Frequency. The original tones were chosen so not only would the tones be unambiguous, but the harmonics and modulation products would not interfere with each other. It's more complicated than you think. DTMF tones only sound correct on a system with no distor...

No it isn't. You're error is too big. Back to the sampling error.

Koz

Are you doing any of this on a video system? That's about the error between drop and non-drop SMPTE timecode. Koz

A possibly unimportant point. 44100 and 22050 are standard sampling frequencies. 22000 is not.

Koz

I still need to get a decent transformer... (which will probably be the most expensive part of the party) I know. http://www.kozco.com/tech/pix/MicAmp2.jpg The big silver transformer in the back isn't the power transformer. That's the output transformer. It will do +24dBm into 600 ohms at any audib...

Two problems you'll probably hit right away are power supply rejection and environment noise. Microphone signals are reeeely tiny and the power supplies are probably ideally +/- 15 volts, filtered very well. If there's -60dB power supply ripple and trash and the chip has a power supply rejection rat...

How much different is it? And which direction? I predict the show in Audacity is too short. Audacity plays shows it doesn't recognize or which may be damaged too fast. Did you create a large montage of different music files from different places? Audacity isn't a very good converter. It's best to h...

I'm running Audacity 1.2 on a Tiger (10.4.11) system, but I'm doing it on an Intel Mac, not a Power PC Mac. You should have downloaded Audacity 1.2.6, not 1.2.5. However, you are urged strongly to give it all up and install Audacity 1.3.12. http://audacityteam.org/download/ Audacity 1.2 is no longer...