Suggestions for used spectrum analyzer?

[ezkcdude]

I'm looking to do measurements on my DAC, and figured there are a lot of use spectrum analyzers available on ebay. Anyone have suggestions for a good model?

[Bernhard]

Most affordable used fft analyzers have only max. 14bit adc = 80dB dynamic range, that is enough for low level distortion measurement but not for fs.
Maybe better use a soundcard.

[SY]

What frequencies do you want to measure? If it's audio band, then Bernhard's suggestion is, I think, the best one- a good soundcard, a small interface box, and an AC voltmeter for calibration/level-setting purposes.

For an all-in-one package, it's hard to do better than an HP3581A. Accurate and reliable down to about -85dBV. Build a notch filter for your fundamental and it's good to better than -100dBV.

[DSP_Geek]

Originally posted by Bernhard
Most affordable used fft analyzers have only max. 14bit adc = 80dB dynamic range, that is enough for low level distortion measurement but not for fs.
Maybe better use a soundcard.

Yup, what Bernhard said. The new soundcards are way better than old spectrum analysers for this kind of work.

You can also improve low-end resolution by building a high gain op-amp circuit, but you have to be very careful about layout and bypassing or low-level noise will swamp any measurement you want to make.

[ezkcdude]

Well, you guys convinced me. I just ordered an E-MU 1212M. That should be a good start.