Accurate 20Hz THD measurement? - Page 2

unclejed613 · 22nd March 2009, 05:48 PM

glad to be of help..... been using spectrum lab for audio analysis and i've learned a few things...... BTW like the DEVO avatar..... the place i work has an equipment status called DEVO where the equipment is non-serviceable. i use one of their album cover pics as a sticky note for DEVO items.

unclejed613 · 22nd March 2009, 05:58 PM

i'd like to get a sound card with a higher sampling rate than 96khz, because there are some uses a sound card can have as a VLF receiver. Spectrum Lab includes some DSP based demodulators and filters and such that can be useful for such an application.... which reminds me, i should check for the latest version....

it's available here:
http://freenet-homepage.de/dl4yhf/spectra1.html

Jeb-D. · 22nd March 2009, 06:58 PM

I'll check it out. I usually use Visual Analyser (yes, they spell it Analyser not Analyzer) which is freeware too. It's pretty lame, but useful and the price is right.

Right now, I'm using an evaluation of Multi-instrument 3.1. It's pretty nifty and has a lot of capabilities, but the user-interface isn't that good. I'm in the process of giving them some feedback how it can be improved. They seem eager to make it as good as they can.

It has a feature called "device test plan", which is pretty much similar to the "sweep" function with an Audio Precision (if your fimiliar). You can setup and run automated frequency and amplitude sweeps while capturing all kinds of data such as THD, THD+N, SNR, IMD, Crosstalk, individual harmonics (2nd-7th), ect. It can create graphs or text data of things like input vs. output amplitude, THD vs. Frequency, THD vs. output level, and so fourth.

I set it up to do an inverse RIAA amplitude + frequency sweep. So when tuning the curve of my phono stage, I just have to try to get the plotted line flat. Makes things much simpler, as I no longer have to compare the amplitude at each frequency to published RIAA curve data every time an adjustment is made.

I'm considering buying it once the evaluation period ends, but may not be able to afford it at this time. So I may need some good freeware till then.

22nd March 2009, 05:48 PM	#11
unclejed613 diyAudio Member Join Date: Dec 2006	glad to be of help..... been using spectrum lab for audio analysis and i've learned a few things...... BTW like the DEVO avatar..... the place i work has an equipment status called DEVO where the equipment is non-serviceable. i use one of their album cover pics as a sticky note for DEVO items. __________________ Vintage Audio and Pro-Audio repair ampz(removethis)@sohonet.net spammer trap: http://www1284177414881.v-dc.net/

22nd March 2009, 05:58 PM	#12
unclejed613 diyAudio Member Join Date: Dec 2006	i'd like to get a sound card with a higher sampling rate than 96khz, because there are some uses a sound card can have as a VLF receiver. Spectrum Lab includes some DSP based demodulators and filters and such that can be useful for such an application.... which reminds me, i should check for the latest version.... it's available here: http://freenet-homepage.de/dl4yhf/spectra1.html __________________ Vintage Audio and Pro-Audio repair ampz(removethis)@sohonet.net spammer trap: http://www1284177414881.v-dc.net/

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22nd March 2009, 06:58 PM	#13
Jeb-D. diyAudio Member Join Date: Nov 2005 Location: SoCal	I'll check it out. I usually use Visual Analyser (yes, they spell it Analyser not Analyzer) which is freeware too. It's pretty lame, but useful and the price is right. Right now, I'm using an evaluation of Multi-instrument 3.1. It's pretty nifty and has a lot of capabilities, but the user-interface isn't that good. I'm in the process of giving them some feedback how it can be improved. They seem eager to make it as good as they can. It has a feature called "device test plan", which is pretty much similar to the "sweep" function with an Audio Precision (if your fimiliar). You can setup and run automated frequency and amplitude sweeps while capturing all kinds of data such as THD, THD+N, SNR, IMD, Crosstalk, individual harmonics (2nd-7th), ect. It can create graphs or text data of things like input vs. output amplitude, THD vs. Frequency, THD vs. output level, and so fourth. I set it up to do an inverse RIAA amplitude + frequency sweep. So when tuning the curve of my phono stage, I just have to try to get the plotted line flat. Makes things much simpler, as I no longer have to compare the amplitude at each frequency to published RIAA curve data every time an adjustment is made. I'm considering buying it once the evaluation period ends, but may not be able to afford it at this time. So I may need some good freeware till then.

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