Products > Test Equipment
DMM with THD capabilities
pope:
--- Quote from: colorado.rob on January 03, 2023, 03:45:43 pm ---A CMU200 with the CMU-B41 audio option can do THD measurements.
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Thank you but this is well beyond my budget and my needs.
Berni:
0.001% is very low THD. The only cheep way of getting there is a high quality USB sound card and then analyzing it using software.
JohanH:
Check the diyaudio forum, soundcards seems the way to go
https://www.diyaudio.com/community/threads/howto-distortion-measurements-with-rew.338511/
Disclaimer, I don't know anything about the software referred to, I imagine there are other alternatives, too.
switchabl:
The QuantAsylum QA403 audio analyzer might fit the bill. 0.001% is well within its capabilities and it has input ranges up to 40 Vrms. But availability has been a problem, it is unclear when they will be back in stock.
On the budget end, you could look at the E1DA Cosmos ADC. It seems to have very respectable performance but there is no built-in generator, range switching (up to 43 Vrms) is fully manual, input impedance is somewhat low and you need to bring your own software.
If you are working with high power amplifiers (or want to make do with an audio interface), you will need external attenuators. This article may be of interest if you want to build one: https://audioxpress.com/files/attachment/2677
tooki:
--- Quote from: HighVoltage on January 03, 2023, 12:51:51 pm ---The Keithley Series 2000 is also THD capable!
"The 2000 THD series of Keithley Instruments are "Total Harmonic Distortion" analyzers, which are used for audio analysis and distortion measurements. The frequency range starts from 20Hz to 20kHz and a built-in low distortion sine wave Generator provide the adjustable signal for testing amplifier stages or speakers for distortion. Thus, for example in the production of mobile telephones, the microphone, the amplifier and the speaker part may be tested with this single device. The full digital multimeter part was taken from the model 2000 and allows measurements of 100 nV to 1000V."
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No, they’re not saying the entire 2000 series is THD-capable. They’re saying the THD models within the 2000 series are THD-capable.
--- Quote from: AVGresponding on January 03, 2023, 01:07:36 pm ---[Obnoxious text styling removed]
You're misunderstanding what the manual is saying. By "2000 THD series", they mean any 20xx THD meter, which is two. The 2015 THD and the 2016 THD.
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Actually, it was four models: 2015, 2015-P, 2016, and 2016-P. The 2016 and 2016-P can output higher voltages on the test signal output, while the P versions can also “identify peak spectral components”. As best I can tell, the 2016 and 2016-P are discontinued. I’ve attached an old datasheet that covers them all. The current datasheet and website list only the 2015 and 2015-P.
(FYI, “THD” isn’t actually part of the model numbers, as there are no 2015/2016 models without THD functionality. The front panel text “2015 THD Multimeter” doesn’t mean it’s the “2015 THD” + “multimeter”, it means it’s the “2015” + “THD multimeter”. In fact, the -P models say e.g. “2015-P Audio Analyzing DMM”.)
--- Quote from: AVGresponding on January 03, 2023, 01:07:36 pm ---The 2000 is just a DMM, and does not have the internal sine generator and THD measurement circuitry. The THD meters are a LOT heavier because they have a LOT more internally going on.
Yes, I am speaking from personal knowledge; I have a K2000 and a K2015THD, the THD meter weighs about half as much again as the plain DMM.
The OP doesn't mention a budget, and idk what the market is like in Greece, but I was patient and paid ~£400 for my K2015THD, with a fairly recent cal.
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I paid about $400 for my 2015, too. It’s hands-down my favorite meter of all the ones I own (K2015, K197, K197A, Fluke 87V, Keysight U1252B, plus some cheapies).
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