Hi All.
I hope that I am posting this in the right place. I need advice on what kind of sine wave oscillator I would need to test loudspeakers. I found what I think would work but am not sure. It's the Rolls mo2020. The only problem that I can see with it is the lowest frequency is 20hz. Is 20hz low enough? I would also like to stay under $100. Any help would be greatly appreciated.
Matt.
I hope that I am posting this in the right place. I need advice on what kind of sine wave oscillator I would need to test loudspeakers. I found what I think would work but am not sure. It's the Rolls mo2020. The only problem that I can see with it is the lowest frequency is 20hz. Is 20hz low enough? I would also like to stay under $100. Any help would be greatly appreciated.
Matt.
1st figure out the testing you want to do then draw up the procedures with test diagrams. nowadays software / soundcards is at the center of speaker testing, the fall out from all those is the test equipment. it's often a mistake to do so in reverse. figure on a calibrated mic, power amplifier, attenuators in addition.
I use SineGen 2.3. Its a Windows PC app that generates sine waves via the PC/Laptop sound card. Use the line out as the audio source for testing.
I've had it for several years and doesn't seem to exist on the apps referenced web page. A google search seems to find a different product of the same name.
It doesn't install. SineGen.exe will execute no matter where its located with just a double click. I keep the app in the folder with my DIY info.
Send me a PM with your email and I can forward a copy to you.
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Why spend money? Most people do sophisticated speaker measurements with integrated software such as Holme Impulse, Room Eq Wizard running on a PC.
HOLM Acoustics
REW - Room EQ Wizard Room Acoustics Software
You also need a measurement-type microphone, but there are USB measurement mic of sufficient quality such as this one:
https://www.minidsp.com/products/acoustic-measurement/umik-1
You also need a PC with a line level output, which most have (earphone or speaker jack)
Thanks for everyone's input. I think you just saved me a $100. The books I'm using maybe a little outdated. Book said to use a sine wave generator or oscillator. Didn't think to use something I already have. I already have the minidsp mic and minidsp four. Haven't used them yet. I have access to several amplifiers, multimeters and an oscope. I have a new laptop that should work. It doesn't have a mic jack but it has headphone and USB. Thanks for all the help.
Matt.
Matt.
Do you have a retired smart phone sitting in a drawer? I use one with a signal generator app for simple testing.
Let's start from the beginning, if you want to measure a speaker frequency response a sinewave oscillator is *useless* , sorry.
All you can do is measure resonance frequency, impedance and TS parameters but you simply can not trace its frequency response with plain sinewaves.
Reason is that real world response is made out of zillions of narrow peaks and dips, varying from +10/15 dB and down to -40dB or worse.
You need to average that data to make any sense.
Old style trick was to "wobble" the test frequency, quickly frequency modulating it within 1 octave, 1/3 oct , 1/6 oct (very popular) and for very detailes Factory testing, 1/20 oct, but never ever a steady frequency, which is what a regular oscillator (analogic or digital) will give you.
Modern method generates narrow band pink noise or plain sends a single narrow pulse and mathematically derives the frequency response out of it.
All you can do is measure resonance frequency, impedance and TS parameters but you simply can not trace its frequency response with plain sinewaves.
Reason is that real world response is made out of zillions of narrow peaks and dips, varying from +10/15 dB and down to -40dB or worse.
You need to average that data to make any sense.
Old style trick was to "wobble" the test frequency, quickly frequency modulating it within 1 octave, 1/3 oct , 1/6 oct (very popular) and for very detailes Factory testing, 1/20 oct, but never ever a steady frequency, which is what a regular oscillator (analogic or digital) will give you.
Modern method generates narrow band pink noise or plain sends a single narrow pulse and mathematically derives the frequency response out of it.
Thanks for the responses. I downloaded REW to my laptop yesterday. What a great piece of software. If I hadn't procrastinated and just downloaded it when I ordered the Umik I wouldn't have needed to post the question. But by posting I have leaned much more. So it's all good.
One question though does the HOLM acoustics software offer any advantages or something different than REW?
Regards
Matt
One question though does the HOLM acoustics software offer any advantages or something different than REW?
Regards
Matt
Dear Matt:
That Rolls Test Oscillator can be quite useful as handy, basic sine/square wave generator. Yes, you got good advice re more sophisticated speaker testing but perhaps you need to get your feet wet? Maybe you'll want to trace some circuits, etc? Maybe see how a simple sig generator can be useful with your projects?
It's often available on Ebay for ~$30USD. The pdf below describes what it can do.
dizmayed
http://www.rolls.com/pdf/M_MO2020.pdf
That Rolls Test Oscillator can be quite useful as handy, basic sine/square wave generator. Yes, you got good advice re more sophisticated speaker testing but perhaps you need to get your feet wet? Maybe you'll want to trace some circuits, etc? Maybe see how a simple sig generator can be useful with your projects?
It's often available on Ebay for ~$30USD. The pdf below describes what it can do.
dizmayed
http://www.rolls.com/pdf/M_MO2020.pdf
Thanks Dizmayed. I do have a Pass amp project that I should start some day and some old car audio amps that might need to be repaired.
Regards
Matt
Regards
Matt
HOLMInpulse is simpler than REW. REW is more like a measurement suite. HOLM is centered around the impulse respomse. I like it, because I've used it for so long.
One advantage HOLM does have it that it need no second channel for timing. It figures that out from a signal channel. You can also import and compare files if you want to, even music clips. Not many people do that, but I've found it handy.
REW is a better all-round choice if you don't mind Java. Plus it seems that development of HOLM has stopped. 🙁
Hi Pano
I know what you mean about Java. I had to download a different browser and Java to run REW. I have had problems with other computers running Java. Had to do software updates all the time to fix problems. I will try HOLM Impulse as well. Will the minidsp Umik work with Impulse? Thanks.
Regards
Matt
I know what you mean about Java. I had to download a different browser and Java to run REW. I have had problems with other computers running Java. Had to do software updates all the time to fix problems. I will try HOLM Impulse as well. Will the minidsp Umik work with Impulse? Thanks.
Regards
Matt
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