Data AcQuisition And Real-Time AnalysisScope - Spectrum - Spectrogram - Signal Generator
Software for Windows
Science with your Sound Card!
Contact us about
This button is only enabled in Match mode.
If you are using the Match calibration method, first load the proper Generator setup, either InvSine.GEN for the cancellation method, or AltSine.GEN for the alternating method. Make sure you understand the basic approach as discussed in the Match Measurements section of the Meter / Match mode control topic. Get all your wiring and speaker placement ready.
Once you have everything in place and the initial levels set as described, hit the Calibrate - Manual Wave or Master button in Attenuator Options to get the respective calibration dialog. Then hit Match, and the Equal Test button will be selected automatically. It will set the same step on both Left and Right attenuators, so you can verify that the two outputs are indeed summing properly to create a null (cancellation method) or a continuous tone (alternating method). In this mode Left Step actually controls the step number for both sides, so you can find a comfortable sound level.
If you are summing your home stereo outputs to a speaker, adjust the stereo's Balance control until you hear a null or steady tone.
If you are using headphones with acoustical summing, move the phones around near your ear until you get a null or steady tone. You will need to maintain this position for the rest of the test. (No, it won't be easy!)
If you are summing the sound card outputs using the built-in mono summing of a laptop, or the Mono summing of a home stereo, or fixed resistors summed to one home stereo input, then you need to adjust the relative levels of the two outputs until you get a null or steady tone. One way to do this is via the Level controls, but you can't get at them while in the Equal mode of the calibration dialog. So you will need to go back to the main dialog, set both volumes to the same fairly loud step number, then enter the Control dialogs as needed. The test tone should be on Stream 0 of each output.
The idea here is to reduce the Left Level if that output is too large (due to mismatched resistors or internal sound card mismatches) until the summed sound cancels (using InvSine) or becomes steady (using AltSine). If reducing Left Level does not produce this result, then it is the Right output that is too large.
However, you must not adjust Right Level, since that is going to be adjusted during the Match process to match the Left. Instead, first try swapping the summing resistors. If that doesn't work, the problem is an internal sound card mismatch. To deal with that, set Right Master volume lower than Left Master (if you are doing a Wave calibration; otherwise set Right Wave lower for Master calibration). You probably won't be able to match the two outputs with Right volume alone, but if you set it a bit lower than the apparent match point you can then set Left Level for a perfect match.
Questions? Comments? Contact us!We respond to ALL inquiries, typically within 24 hrs.
Over 30 Years of Innovative Instrumentation
© Copyright 2007 - 2017 by Interstellar Research
All rights reserved