Tweeter alignment

[keep_hope_alive Premium Member]

don't forget that you localize sound based in time arrival (ITD) for frequencies below ~3kHz and you localize sound based on intensity (IID) above ~3kHz.

Crossover point and slope should be taken into account here. A 3kHz 12dB/oct slope does not get you above the IID point. a 4.5kHz 12dB/oct slope is a better point. The reason should be obvious; the speaker will be audible below the crossover point. When a source is 10dB down relative to other sources, it no longer adds to the cumulative sound pressure level. In other words: if you have two sources producing the same frequency and one is 10dB lower than the other, you only measure one source.

This is why people will say that T/A on tweeters isn't necessary - just proper aiming. What they should clarify is that the statement is only true for crossover points/slopes above a certain frequency. most component sets use a crossover point below 4kHz, so when using passives, you are best to just T/A the whole set - locate your tweeters at a distance from the nearest headrest that is equal to the door woofer, and aim them off-axis relative to the nearest seating position. naturally, this is a general statement and each vehicle should be tested.

lastly, T/A is not a requirement for a good soundstage. it is a bandaid for poor placement/installation. sadly, our cars are poor environments for speaker placement. we do our best with placement/install, then use tools are our disposal to fix what we can.

 

[keep_hope_alive Premium Member]

if the OP hasn't realized this already - he should relocate his tweeters, and aim them more off-axis to the nearest seat.

one side-effect of aiming off-axis is the specular reflections you get from the side window. this is evident if your soundstage changes with windows down vs. windows up. for the driver: the specular reflection off the side glass will give right channel information to the left ear at a similar SPL, but at a delayed time. controlling this is important - and one challenge of a-pillar tweeters.

 

[zako 10+ year member]

time alignment is important for ALL speakers in the car. not one single speaker will sound good with the sound arriving late to your ear

I still disagree. Let's start with time alignment of your front stage with the subwoofer (assume, all front stage is already time aligned). I have spent a while looking for the correct music track with the correct midbass notes to try time alignment for the subwoofer. After spending some time trying to time align the subwoofer with the front stage, I would say yes, it can make a barely audible difference. However, it's not a night and day difference. Once the front stage is time aligned with the subwoofer, the subwoofer is fully in phase with the front stage and certain bass notes will sound fuller. But like I said, it's not night and day, and you need to listen for the right things on the right track to be able to detect the difference between TA and no TA. So based on this experience, I certainly prefer to time align the subwoofer with the front stage now, but it's not like my sub sounded bad without TA to begin with..

The speakers that benefit most from time alignment are those that play up to the upper midrange. This is because those are the frequencies where time differences are responsible for your brain deciding whether the sound comes from right or left. For your tweeters, if they don't play into upper midrange, TA may be useful to make your tweeter be in phase with other speakers. But when the tweeters are not time aligned with each other, it's not like they're going to screw up your imaging. Now, let's not stray away from the original questions. The OP needs to know how to place cymbals correctly in the sound stage. If the op tries to time align tweeters with each other, likely, this will not fix this issue. Moreover, since he is running passive, woofers are not time aligned with each other any more (if they were to begin with), and this will cause much bigger imaging problems.

 

[keep_hope_alive Premium Member]

I agree with Zako.

Time alignment for a subwoofer is minimally important, and really depends on the LPF. Getting speakers in acoustic phase first requires the wave is fully developed. 50Hz has a wavelength of 22.5 ft. It will not develop inside the car. Even 100Hz with a 11.5 ft wavelength will not be developed. T/A has little to no benefit here. If anything, you are aligning the harmonics. Polarity, or just making sure all drivers are moving in the same direction relative to the listener, is important since we are basically pressurizing the cabin. Bass is lost when some drivers push out and others pull in. This is not the same as time arrival cancellation, but instead just pressurization cancellation (if such a term exists).

*assumes 1125 ft/sec for speed of sound

Mid bass arrival times can matter, but it is a function of ITD and PLD. Given the choice to T/A a component set with passive crossovers, split the difference or base it on the woofer.

Many tweeter problems are diffraction based and not fixed by T/A anyway.

Driver placement and aiming, enclosure construction, and crossover point/slope play the largest role in how a speaker system will sound. This is true for home, pro, or car audio.

 

[cablguy184 10+ year member]

I agree with Zako.Time alignment for a subwoofer is minimally important, and really depends on the LPF.

Driver placement and aiming, enclosure construction, and crossover point/slope play the largest role in how a speaker system will sound. This is true for home, pro, or car audio.

True ... True ... True ...

Most Sound Quality competitors BARELY run sub drivers during competition ...

Installation is the KEY !!! Deadning, air tight sealing ... and ALL the above factors is a MUST before time alignment / processing is even thought about ...