Tips on time alignment?

[hpyle]

I'm wondering if anyone has tips on how best to time-align mid and tweeter drivers. So far I've done it "by eye", and I've measured the full-range impulse response where I can see a slightly ragged first peak (http://www.inguzaudio.com/Data/20070620_JHorn_IR.PNG). But my neighbors' patience will run thin pretty quickly if I run too many more sweeps.

Suggestions?

[boputnam]

...and I've measured the full-range impulse response ...

Run the impulse response by band pass - this will show the network-related "time" affects, however, you'll need to measure/watch phase, too.

[WTPRO]

Hi

Keep in mind that to be 'time aligned' the crossover lead (tweeter) and lag (woofer) delay at the crossover point needs to be considered. This changes with crossover topology (1st, 2nd 2rd order) as well as any phase or amplitude induced anomolies from the drivers.

About the only way to really tell is put the two drivers on a baffle and measure the delta phase at the crossover point. This can be done by FFT generated 'brick wall' high and low pass filter outputs to the left and right channels. These are then connected to the two drivers. All you then need to do is look at the phase at the hypothetical crossover point and reverse work the phase into a delta distance. The next step is considering how the theoretical phase slopes and amplitudes work with the various topologies. The challange is then to divine from the available data the best high and low pass topology.

BTW, I noticed the 'Cambridge Ma', PM me for more details.

Best regards,
Keith Larson

[Thom]

This is one of several ways to test neighbors to see if they may need replaced soon.

[boputnam]

Keep in mind that to be 'time aligned' the crossover lead (tweeter) and lag (woofer) delay at the crossover point needs to be considered. This changes with crossover topology (1st, 2nd 2rd order) as well as any phase or amplitude induced anomolies from the drivers.

Keith's got it.

This complexity is easier dealt with in the digital domain (system DSP) - but that may not be where you are headed...

[stuck.wilson]

typically, for my two way system-- i use music heavy in the XO region (mine's about 1100-1200 hz), so i use piano jazz, which'll distort to my ears if not aligned.

i also use music with ambient sounds present-- decay time is really affected by misalignment-- you seem to get the best decay times with well aligned drivers.

measuring-- folks usually either work for the biggest null out of phase, or the biggest amplitude at XO with RTA.. i don't have such capacity-- but i hear it works well..

luck!

d