What do you all use for measuring active EQ circuits?

This may be a really dumb question to all you folks but...

What do you use to measure frequency response of active EQ and crossover circuits?

I have the Dayton DATS v3 and Omnimic V2 but as of recently, have been building a lot of active EQ and crossover circuits. Realized I have no way to really measure the final performance of these circuits.

What exactly is everyone using to get the nice frecuency-sweep graphs that I see in various places? Just some PC software w/ a passive "plug in" soundcard jig or something with dedicated hardware?

-Dean
 
Hameg HM-1505 analogue oscilloscope with cursors, 1:1 probes, CD player, test CD with sine waves of many frequencies. Always measure the input and the output signal, preferably with the same oscilloscope channel, so the CD player's response drops out of the ratio. It takes some manual work and doesn't result in pretty plots, but the measurements are pretty accurate. You can always use Excel, Libre Office Calc or Gnuplot to make a plot afterwards.
 
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A sound card is all you really need. Then some software that can provide a sinusoidal output signal and sense the voltage at the line input of the sound card. Connect the filter between the output of the sound card and the input. Then sweep the frequency of the output and plot Vout/Vin as function of frequency.

Holm Impulse is one option. Fuzzmeasure is another. As others have pointed to, ARTA, REW, etc. works too.

Tom
 
REW is the class leader here, with any audio interface you have.

I've owned an Audio Precision Analyzer, still own a PrismSound dScope and would happily use REW plus my interface for benchwork at line level. For measuring amplifiers it takes more car but is still possible.
 
REW, Atra, SpectraPlus, WaveSpecra + WaveGene, etc.

You do not need a special hardware (like ADC for measurement) for just a frequency response - any sound card will do the job.
Just to test it's own frequency response is in the loop, and make correction, if need.

Measuring can be provided in different ways:
- a set of fixed frequencies,
  • sweep frequency
  • white noise.

Last option is less accurate, but fast (close to real time) and convenient.

Alex.