Hi all,
what test equipment is recommended for meusurements of speakers to tine tune the design (open baffle --> shape) and crossover design?
I already bought a mic (omnitronic mm-1c) with stand.
I want to do the measurements with my laptop, so I need an audio-interface for output (ideally cinch) to amp--> speakers and input for the mic.
Most audio interfaces with mic preamp seem to have only line (6.3 mm) in/ouputs but not cinch.
What is better: "Standalone" mic-preamp and very simple audio-interface with cinch, or an audio-interface like Steinberg ur12?
Are the outputs independant so that I can use them for the e.g. sweep output and record the mic simultaneously?
what test equipment is recommended for meusurements of speakers to tine tune the design (open baffle --> shape) and crossover design?
I already bought a mic (omnitronic mm-1c) with stand.
I want to do the measurements with my laptop, so I need an audio-interface for output (ideally cinch) to amp--> speakers and input for the mic.
Most audio interfaces with mic preamp seem to have only line (6.3 mm) in/ouputs but not cinch.
What is better: "Standalone" mic-preamp and very simple audio-interface with cinch, or an audio-interface like Steinberg ur12?
Are the outputs independant so that I can use them for the e.g. sweep output and record the mic simultaneously?
One more question: Mundorf sent me recommendations for filters (Zobel) to be applied to their AMT for resonance damping. But they wrote that these are starting points and need to be modified based on actual crossover design. How do I decide what values I actually need? Do I do that based on measurements (which?) or purely based on the final design of crossover frequencies once I know them?
One precision regarding the filter recommended by Mundorf: They wrote that this is espeically helpful for the Dipole models (noch backplane). If I need software to model this, how do I do this when T/S parameters are not avialable (because not applicable for AMTs)?
Here is the recommended filter: CLR series in parallel to tweeter with values: C 3.9 uF, L 2.7 mH 1.5 Ohm, R 5.6 Ohm.
Here is the recommended filter: CLR series in parallel to tweeter with values: C 3.9 uF, L 2.7 mH 1.5 Ohm, R 5.6 Ohm.
OK, I found the answer regarding the AMT myself: The CLR dampens the resonance peak at 1.5kHz of the AMT for those cases where this frequency is too close to the crossover frequency.
Another question: Has anyone tried this testboard-kit for impedance measurements:
https://www.analog.com/en/analog-dialogue/studentzone/studentzone-april-2019.html
Another question: Has anyone tried this testboard-kit for impedance measurements:
https://www.analog.com/en/analog-dialogue/studentzone/studentzone-april-2019.html
You'll need tools for acoustic and electronic testing. And a software package that will deal with the measurements.
Acoustic: impulse response, step response, SPL response curves, etc. You'll need microphone and an audio interface. I hope your microphone is not one of those newfangled USB mics. The microphones with a good old analog output are better suited to get time-coherent measurements. If your audio interface already has a built-in microphone amp you don't need a dedicated mic amp. Make sure the audio interface works fine with your computer (Windows often needs special drivers for a given interface, whereas macOS and Linux tend to be a lot easier with this).
Electronic: a simple resistor is most likely all you need to measure impedance curves. It depends a bit on the method(s) implemented in your software package.
Software: there are a gazillion of different tools out there. Arta and REW are popular and capable. I like MATAA, but it has a steep learning curve. Reading software manuals is a great way to learn about loudspeaker testing.
Acoustic: impulse response, step response, SPL response curves, etc. You'll need microphone and an audio interface. I hope your microphone is not one of those newfangled USB mics. The microphones with a good old analog output are better suited to get time-coherent measurements. If your audio interface already has a built-in microphone amp you don't need a dedicated mic amp. Make sure the audio interface works fine with your computer (Windows often needs special drivers for a given interface, whereas macOS and Linux tend to be a lot easier with this).
Electronic: a simple resistor is most likely all you need to measure impedance curves. It depends a bit on the method(s) implemented in your software package.
Software: there are a gazillion of different tools out there. Arta and REW are popular and capable. I like MATAA, but it has a steep learning curve. Reading software manuals is a great way to learn about loudspeaker testing.
Thanks for the suggestions. As written above, Mic is omnitronic mm-1c. I do not have an audio interface yet (other than laptop headset-jack), any suggestions that would work for both sensitivity and impedance measurements?
For MICs to be used with measuring I recommend "HAUN MBC550" and "Beyerdynamic MM1". Both are that linear that they can be used even w/o calibration compensation - allthough curves are provided. Especially the Haun is worth to be used in quality recordings too. I am using them for DECCA Tree setups in small orchestras like string quartetts.
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Any half decent 2 channel USB audio interface will do the trick, I use Steinberg UR22mkii and it's great! For a mic, a calibrated mic would be a better option but at least you have something to start with to learn the tools and design process.
The key to using this equipment for speaker impedance and time accurate acoustic measurements is a simple jig that is basically a voltage divider to step down the speaker level signal to line level. For acoustic measurements 1 channel is the mic input and the other is a feedback reference of the electrical signal at the speaker, which allows for accurate time of flight between speaker and mic, and some compensation for non-linearities of the audio chain PC to speaker.
I've attached my simple jig schematic, not sure how deep into it you want to get in this thread, but it will work with ARTA, REW, or SoundEasy. I recommend ARTA and VituixCAD for measurement and design tools.