# Search results

1. ### How to create periodic PCM test tones with high inter-sample peaks

How to create periodic PCM test tones with high inter-sample peaks
2. ### How good is your PCM sine wave test tone? Niven's theorem is your friend.

Thanks for the feed back. I just finished a massive rework to fix the level problem. I also removed the 3:1 and 6:1 examples from the perfect directory due to imperfect level. That leaves the only 4:1 examples as 'perfect'. I at least had to try calculating true peak. Even for the very simplest...
3. ### How good is your PCM sine wave test tone? Niven's theorem is your friend.

Well for point number 2, I must be losing my mind. I do realize the presets are powers of two, but I thought for sure I typed in other values and saw them pop back to a power of two. But I cannot reproduce that today. I tried everything. But now that I can change that value, I can have better...
4. ### How good is your PCM sine wave test tone? Niven's theorem is your friend.

Thanks for looking at it. Something really strange is going on. You're app is a little short on symbols for easy debugging. The farthest I can see the code get for the 15 kHz sine generation is here: MathNet.Numerics.IntegralTransforms.Fourier.FrequencyScale(Int32 length, Double sampleRate) So...
5. ### How good is your PCM sine wave test tone? Niven's theorem is your friend.

Yes exactly. Well stated. At first I did my debugging of SpectrumViewer, an old-school filter bank spectrum analyzer emulation, with Windows audio. I quickly learned I would pull my hair out that way and switched to wave files. I noticed that the number of noise harmonics varies with the...
6. ### How good is your PCM sine wave test tone? Niven's theorem is your friend.

Thanks for looking at it. The analyzer I am using is the old-school filter bank kind, so there is no FFT and therefore no windowing. I figured out the problem: The Rew generator is clipping without any indication of clipping. For the settings I used (Klingelnberg, 44100), Rew allows me to put...
7. ### How good is your PCM sine wave test tone? Niven's theorem is your friend.

I checked some Rew test tones, and one has a unique problem. It's the Klingelnberg 10.5K, 19K, 20K: https://notabs.org/audiosciencereview/REW/video/Spectrum%20Viewer%201.21%20%20%20_Triple_10k5_19k_20k_589_mV_44k_PCM32_rew.wav_%202023-01-14%2000-09-41.mp4
8. ### How good is your PCM sine wave test tone? Niven's theorem is your friend.

Here is a video of 15KHz sine from Multitone Analyzer that shows shows the sine angle error accumulation problem: https://notabs.org/audiosciencereview/sine15kVideo/sine_15kHz_mta.mp4 Here is what I would expect: https://notabs.org/audiosciencereview/sine15kVideo/sine_15kHzExpected.mp4 I did a...
9. ### How good is your PCM sine wave test tone? Niven's theorem is your friend.

The reason I thought nobody was using inverse FFT for tone generation is the generally dismal state of free test tones I find. For the one I tested (FFTW), the output has better accuracy than what I find here. However, as of today I can no longer say I have found no test tone files that are...
10. ### How good is your PCM sine wave test tone? Niven's theorem is your friend.

If people here are asked to evaluate the quality of a steady (periodic) test tone, no doubt FFT is going be the tool of choice. It's a natural fit because because in the case of a periodic signal and no overlapping windows, no windowing functions, and no averaging, FFT extracts enough...
11. ### How good is your PCM sine wave test tone? Niven's theorem is your friend.

I have yet to see a sample wave file here that is at the numerical limit of accuracy for 24-bit or better, as measured by command line FFT (plotting FFT rounds the values to fit the nearest pixel, loosing detail). An example is the Audio Precision test tone linked earlier. It is very good...
12. ### How good is your PCM sine wave test tone? Niven's theorem is your friend.

It's really just a software challenge to me. I'm retired and getting old. At first I wanted all garage hobbies for retirement, like fabrication and machining. But my blurry eye sight takes some of the fun out of those things. So now I spend part of the day playing with the computer, with the...
13. ### How good is your PCM sine wave test tone? Niven's theorem is your friend.

I mis-spoke. What I am talking about is better described here. A 1000 Hz tone encoded at 44100 samples per second, with no partial cycles has 220 harmonics. That's because 441 samples encodes 10 complete cycles before the pattern repeats. 441 / 2 gives the potential number of harmonics (or...
14. ### How good is your PCM sine wave test tone? Niven's theorem is your friend.

I agree. Isn't this the same as saying the test pattern should contain whole sine wave cycles, and not truncate a sine wave mid cycle? Of the Multitone Analyzer pre-built test files, I looked at 'Multitone 20 44100 64bits'. Viewing a the spectrum in real time shows a jump every 5 seconds. The...
15. ### How good is your PCM sine wave test tone? Niven's theorem is your friend.

My point is that the sample Audio Precision test file provided by Amir isn't perfect and can be improved. I improved it.
16. ### How good is your PCM sine wave test tone? Niven's theorem is your friend.

I agree. I made the error-free files as a personal challenge. The easiest way to get to the top of Mt Everest is helicopter. But some people climb it for the challenge.
17. ### How good is your PCM sine wave test tone? Niven's theorem is your friend.

I think what you are saying is equivalent to using a whole number of sine cycles in the test pattern. At first, I was accidentally truncating the tones at an arbitrary point, such as 10 seconds. This doesn't affect high frequencies much. If a high frequency tone of 200,000 cycles comes up short...
18. ### How good is your PCM sine wave test tone? Niven's theorem is your friend.

Bug fix: Double precision floating point as used in 64-bit wav files are good for 53 bits of precision. Yet Multitone Analyzer reports ENOB of only 52.7. I added a new set of wave files (APx555_Multitone_32_192_24_test_v2.7z) that corrects the problem, which affects only the 64-bit version. The...
19. ### How good is your PCM sine wave test tone? Niven's theorem is your friend.

A while back, Amir posted this sample test file from AP that is presumably high quality. Yesterday I decided to try to rebuild it with increased bit depth. It's a multitone file containing 32 steady sine waves. Their frequencies are spread roughly log scale. The first thing I checked for is any...
20. ### How good is your PCM sine wave test tone? Niven's theorem is your friend.

Thanks for the screen shots. I already found a related wav file of yours, APx555 Multitone 32 192 khz 24 bit.wav. Do you have any sample wave files for single tones I could look at? Thanks.