Hi,
Started on my first two-way project (SB12PFC25-4 + SB19ST-C000-4 in a 7L vented box).
I just built Rod Elliot's "test box": Loudspeaker Test Box
As he describes it "No maths, no spreadsheets, just a quick frequency scan and twiddle a couple of knobs to get the values needed".
First I need something to generate a sweep. I found this tutorial by Claudio Negro (Claudio Negro's home page, how to project and test a loudspeaker using Speaker Workshop) which I guess I can follow not only to generate a sweep but also to capture impedance graph. Is it a good option or there is an easier one?
Second question is where to start with cap/resistance knobs. I think there are way too many combination for the process to be be "quick". Any suggestions for the initial settings for the knobs? Should I use some online calculator, and then twiddle a bit to see how it affects the curve?
Third question. Is it actually worth doing it? Can I just measure impedance curve and frequency response and then model zobel and crossover in XSim?
Oh, and one last question! Should I measure impedance in free air or in a box?. Basically should I build test box close to final dimensions before attempting to measure?
thanks
Vladimir
Started on my first two-way project (SB12PFC25-4 + SB19ST-C000-4 in a 7L vented box).
I just built Rod Elliot's "test box": Loudspeaker Test Box
As he describes it "No maths, no spreadsheets, just a quick frequency scan and twiddle a couple of knobs to get the values needed".
First I need something to generate a sweep. I found this tutorial by Claudio Negro (Claudio Negro's home page, how to project and test a loudspeaker using Speaker Workshop) which I guess I can follow not only to generate a sweep but also to capture impedance graph. Is it a good option or there is an easier one?
Second question is where to start with cap/resistance knobs. I think there are way too many combination for the process to be be "quick". Any suggestions for the initial settings for the knobs? Should I use some online calculator, and then twiddle a bit to see how it affects the curve?
Third question. Is it actually worth doing it? Can I just measure impedance curve and frequency response and then model zobel and crossover in XSim?
Oh, and one last question! Should I measure impedance in free air or in a box?. Basically should I build test box close to final dimensions before attempting to measure?
thanks
Vladimir
Third question is most important. 
No, not worth doing.
For T/S values, use free air. This is what you use for box design.
For impedance, you should design your crossover with the in-box measurements, but for tweeters and sealed midrange drivers this is essentially the same as free-air. This is part of what you will need for crossover design.
If you wish to buy, DATS or OmniMic+DATS is a great choice. Otherwise, you can use Room EQ Wizard with a home made jig to get the necessary measurements.
Best,
E
No, not worth doing.
For T/S values, use free air. This is what you use for box design.
For impedance, you should design your crossover with the in-box measurements, but for tweeters and sealed midrange drivers this is essentially the same as free-air. This is part of what you will need for crossover design.
If you wish to buy, DATS or OmniMic+DATS is a great choice. Otherwise, you can use Room EQ Wizard with a home made jig to get the necessary measurements.
Best,
E
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