BillFitzmaurice.info

So i have a question

Why its it that i don't have to delay the Otops. The sound waves have to travel through the the much longer horn path and the tubas which would cause
the Bass & mid high not be be aligned. At least that my take on it.

But yet i cant hear any miss alignment

You can't hear it because your hearing isn't that acute below 100Hz. If the crossover to the subs was at 500Hz it would be very obvious. Back in 1936 almost every theater in America had to toss their speakers because they did crossover at 500Hz and weren't time aligned, replacing them with the Shearer Horn, which was time aligned.
http://www.audioheritage.org/html/profi ... hearer.htm

Cool, thanks.

What!? It depends on my speaker placement, but if my t24 is 2ft behind my tops, then I delay my tops by about 9ft (because of the ~7ft horn length). At least that's how I understand it.

You can delay the tops to the subs if you wish, the point is that you may not have to. In a band setting it's critical to delay the tops to the backline, because in that case lack of time align will be heard.

Bill Fitzmaurice wrote:You can't hear it because your hearing isn't that acute below 100Hz. If the crossover to the subs was at 500Hz it would be very obvious. Back in 1936 almost every theater in America had to toss their speakers because they did crossover at 500Hz and weren't time aligned, replacing them with the Shearer Horn, which was time aligned.
http://www.audioheritage.org/html/profi ... hearer.htm

Do you know up to how much time delay / distance you won't notice delay below 100Hz? Because at i.e. 1s/1000ms (340m/ 1000feet) I sure do. To bad my PA2 doesn't let me put in a delay bigger then 10ms where I had noticed that time alignment for my subs didn't do much to the sound I percieve.

From slide 39 of this presentation:
"* Very small delayed signals, like diffraction from cabinet edges, etc. are likely to be audible
* The audibility increases with the amount of the linear distortion and its delay time (This is not surprising)
* The most interesting effect is that the audibility increases with signal level"

From http://gedlee.azurewebsites.net/Papers/papers.aspx Where you also find the papers with details which are the basis of this presentation.(summary)

Other interesting things he found are "* THD and IMD have no correlation to the perception of the distortion that they are intended to represent." and "One of the most important implications is that distortion in loudspeakers could well be an insignificant factor" (slide 25)

As long as the linear distortion (frequency response) is ok, it would be fine.

Think wrote: Do you know up to how much time delay / distance you won't notice delay below 100Hz? Because at i.e. 1s/1000ms (340m/ 1000feet) I sure do.

I guess we should all be sure then not to place our mains and subs 1000 feet apart.

Bill Fitzmaurice wrote:

Think wrote: Do you know up to how much time delay / distance you won't notice delay below 100Hz? Because at i.e. 1s/1000ms (340m/ 1000feet) I sure do.

I guess we should all be sure then not to place our mains and subs 1000 feet apart.

I noticed that 'allready'.....

pretty interesting article: https://www.soundonsound.com/sound-advi ... hear-pitch

"Delay Becomes Comb Filtering

Take a mono file, put it on two tracks and delay one of the tracks, but this time don't pan anything to the left or right. If we set the delay at one second, we hear the same sample played twice. As we reduce the delay time to 15ms or so (the lower threshold of perceptual integration, in this case), the delay disappears and is replaced by a comb filter. This works even better using a multi‑tap delay. With a delay value set at 1s, we hear the original sample superimposed with itself over and over again, which is to be expected. At a delay value approaching 40‑50ms (theupper threshold in this case), we still can distinguish the different delay occurrences, but the overall effect is of some kind of reverb that recalls an untreated corridor. Getting nearer 10ms (the lower threshold in this case), we only hear a comb filter. "

15-30 ms or feet would be the limit then.

But this would imply that combfiltering is no issue under 100Hz.

PrismAudio wrote:So i have a question

Why its it that i don't have to delay the Otops. The sound waves have to travel through the the much longer horn path and the tubas which would cause
the Bass & mid high not be be aligned. At least that my take on it.

But yet i cant hear any miss alignment

Simply put, if you can hear a time alignment issue, and you have the means to address it, you should.
Fortunately humans are wonderfully adaptive and can adjust to and tolerate small mistimings.

Perhaps more important than addressing time alignment is ensuring your subs and tops are in phase at the crossover point.
And remembering that the moment you apply delay, you alter phase.

It seems really simple to say "ensure your subs and tops are in phase", but if you want to learn more, please read more.
Changes in gain alter the electronic crossover point to an acoustic crossover point, and that needs to be calculated.
EQ also alters phase, and as already mentioned, so does delay...