![]() I've found it very difficult to get meaningful measurements below that in room. If you are only doing a two way then the above should be "good enough" I get usable measurements down to about 250 Hz off my verandah pointing into the yard. It won't tell you if your mic is accurate (ie flat FR) but it will tell you whether you have measurements that you can trust for getting good results with the simulation. If your simulated and measured results are very similar in spl and phase then your measurements can be trusted for the crossover design. (I actually use speaker workshop for the simulation and the comparisons, but the above should be fine). Compare it to the actual measured result. Don't put in any Z offset information.Įxport the simulated crossover and import it back into holm impulse. Load your frd and impedance measurements into PCD and put in the details of the crossover components you used for the third measurement (make sure you put in coil dcr). You would be surprised what interference will show up in the impedance plot. Now connect a simple crossover (it may be one you have been working on)ĭo a third measurement (again don't move anything).ĭo your measurements of the impedance of each driver in the box at a fair distance from any other objects (you might as well do them in the same spot you had the speaker for the FR measurements). Go back to the measurements tab and measure the woofer (don't move anything). ![]() then click on the Use button beside last detected. Go to the second tab and select time zero locked. Change the Time Zero auto detect to highest positive peak. Go back to the measurement tab and click options for the measurement. Take a measurement of the tweeter with Holm and check the impulse, if it looks upside down (main peak going down rather than up) toggle the "Invert recorded Signal" tickbox on the first tab. Place your mic about 1M away on axis with the tweeter. Position your speaker as far from any objects you can preferably at an angle to any parallel walls (even better do it outside) Try for mid way between the floor and ceiling. Hi Thump Lump, what I suggest as a "test" of whether your measurements are ok or not is to do the following: ![]() ![]() My setup (mic some 80cm to the driver) limit the valid range to above 200-250Hz, under that frequency I have to measure near field, and merge the two measures. ![]() Looking at the impulse response it is obvious where the first reflection kicks in. The length of the gate is dependent of the space around, what is important is the difference in path from the straight distance from driver to mic and the reflected one. And of course you'll find this effect only after you built the enclosure.Įither way you should always use the quasi anechoic method with a gate, in order to leave out the reflected sound. a bump in the response in both the "natural" FR of the driver and the enclosure. The only problem with this approach is that if the enclosure adds some effect in the same way as the driver, i.e. The alternate method is to measure the drivers in the final enclosure. See here for this kind of setup: Zaph|Audio If you have access to an infinite baffle setup you could measure the drivers in such a way, so you can use the data and simulate whatever enclosure you want before physically build it. ![]()
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