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Measurement Systems

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I am finally ready to buy a measurement system. I need a calibrated mike, a signal generator and software to display frequency, impulse and distortion.

I've looked at various reviews of the packages out there, and I need something better than 1/3 octave resolution. It would be nice if it is Mac compatible, but I have a Win laptop so that's not a deal breaker.

Any recommendations welcome and TIA!

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Room EQ Wizard (REW) works for me.  It does all that you've mentioned, plus a lot more.  Here's a link to a thread where many of the different plots/measurement types are shown:-- here and here.  You can also look at Omnimic if you want to buy everything as a package.  Personally, I'd buy the calibrated USB microphone at miniDSP (UMIK-1).

 

There are other packages available that you can pay for: ARTA, Acourate, etc.  For me, I don't see any advantages of these tools over REW.

 

Chris

 

 

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If you're looking for impedance measurements, etc. I find that DATS (available from Parts Express) works well.  I don't use it often, but when I do, it's a snap and it produces good data.  Below is the impedance of a TAD TD-4002 driver on a K-402 horn:

 

TAD TD-4002 on K-402 impedance-phase.GIF

 

Here is the measurement for a Crites 15" cast frame woofer and showing the data for the T/S parameters:

 

983159336_Crites15inchcastframewooferimpedancescreenshot.thumb.JPG.0fac36d85df7ec554d1e422768f999da.JPG

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'Course the impedance info is really only needed if you're designing a passive balancing network; or determining which output tap would be best to use if going that route.  Or designing an enclosure, maybe.

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I don't use DATS often, mostly just to check consistency of impedance measurements between drivers, etc.  The fully horn-loaded loudspeakers with which I'm into DIY aren't that  sensitive to box parameters, but bass reflex is more sensitive to box size...hence the size of the Cornwall box.

 

BTW: yesterday I plotted the group delay of the K-402-MEH, Jubilee and the Cornwall (1979 model, no correction/EQ) to see the rise in group delay due to the reflex ports.  The Cornwall port resonance frequency looks to be about 35 Hz, while the woofer resonance seems to be about 52 Hz in the box.  Note the scale (i.e., zoomed out on the vertical axis group delay).  Group delay values above one half to one period (i.e., 1/2*frequency to 1/frequency) at the frequency of interest are typically audible.  The smaller the relative group delay, the cleaner the sound and with an increase in perceived bass response: 

 

340809254_Cornwall(red)Jubilee(blue)andK-402-MEH(green)GroupDelay.thumb.jpg.00b6467b6d4fb523da9b12f507428e4f.jpg

 

Chris

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1 hour ago, glens said:

'Course the impedance info is really only needed if you're designing a passive balancing network ... [o]r designing an enclosure, maybe.

 

I've been doing both, lately. DATS made it all very easy. Also great for designing Zobel networks.

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Just the other day I was reading up on some stuff.  I really like the idea of making a Zobel to smooth the impedance and then, leaving it with the driver, figuring the filter.  But even so, active really is the way to go...

 

Last I'd played with it, things were yet analog.  Digital is so much better.

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37 minutes ago, glens said:

Just the other day I was reading up on some stuff.  I really like the idea of making a Zobel to smooth the impedance and then, leaving it with the driver, figuring the filter.  But even so, active really is the way to go...

 

Last I'd played with it, things were yet analog.  Digital is so much better.

 

For my main listening room, everything is active. In my other rooms, simplicity is key, and analog still reigns.

Here's before and after when I added a Zobel to a tweeter, with help from DATS and SPICE (for circuit analysis).

Zobel.png

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