Best crossover point between 400hz and 1000hz?

[DDF]

I'm not clear on what you're saying here, I think the "(headphones)" is throwing me off.

Are you saying that at 400-Hz (for example), a 1ms difference (or a foot path of air) between drivers (like a woofer and a midrange) is unrecognizable?

Is there a table or a way to derive the time from the frequency?

Easiest way to remember is 1kHz wavelength ~ foot, and it all scales off that (500Hz = 2 ft, 2 khz = .5 ft...). I thought Bill was saying that group delay distortion (ie different frequencies having different delays to your ears) was most audible 300-700Hz, but its not what he was saying.

No, I wan't saying moving the driver a foot is unrecognizable. It will change the off axis radiation pattern which changes total power response, response at reflection points etc and that's audible. What wouldn't be audible is the effect on group delay, the limits of audibility of which was studied using headphones

[DDF]

Are you referring to those tests they did in the 30s with the big horn cabinets in movie theaters, moving the cells back and forth and listening? I remember those but nothing else that would qualify as 'well known". Those test were particular to a really different set of radiation patterns, box sizes and listening venue than a set of home speakers.

If you're referring to something else, I'm not aware of it but would love to hear about it.

Bill, PS not trying to play gotcha, sincerely curious. Are you referring to the fact that 300-700 Hz is the meat of the vocal range? I agree getting the xover wrong in this range is the worst range to get it wrong, but I think a properly designed xover and driver compliment would work fine in this range.

[philthien]

Group delay audibility threshold (headphones) is 1ms worst case at 400Hz to 5 kHz, and 2ms at 200Hz, but the 1 ms difference is a foot of air path difference. No way you'll hear a fraction of that difference especially in a room with reflections.

I'm not clear on what you're saying here, I think the "(headphones)" is throwing me off.

Are you saying that at 400-Hz (for example), a 1ms difference (or a foot path of air) between drivers (like a woofer and a midrange) is unrecognizable?

Is there a table or a way to derive the time from the frequency?

[DDF]

I said nothing about group delay. The problems that can arise with a crossover in the 300-700Hz range have been well known since the 1930s. Check your back issues of the JAES.

Are you referring to those tests they did in the 30s with the big horn cabinets in movie theaters, moving the cells back and forth and listening? I remember those but nothing else that would qualify as 'well known". Those test were particular to a really different set of radiation patterns, box sizes and listening venue than a set of home speakers.

If you're referring to something else, I'm not aware of it but would love to hear about it.

[billfitzmaurice]

I said nothing about group delay. The problems that can arise with a crossover in the 300-700Hz range have been well known since the 1930s. Check your back issues of the JAES.

[DDF]

That's where our ears are most sensitive to the effects of delays between multiple sources.

Group delay audibility threshold (headphones) is 1ms worst case at 400Hz to 5 kHz, and 2ms at 200Hz, but the 1 ms difference is a foot of air path difference. No way you'll hear a fraction of that difference especially in a room with reflections.

[isaeagle4031]

Anything below 800Hz can be an issue, so it's an area to be avoided.

Say what???????

I guess that means most 3way designs have no chance of working properly. Good grief!

[philthien]

Time align is most critical in the 300-700Hz range, to the extent that it can be very audible when it's off, so if you lack the ability to time align either by physical placement or electronic means you're better off not crossing over there, choosing your drivers accordingly.

Got it, thanks.

[billfitzmaurice]

it would be interesting to leran more on Why this region is more vulnerable to cross in.

That's where our ears are most sensitive to the effects of delays between multiple sources.

And what to do IF you want to use a 10-12” woofer. 1000 Hz is much.....

Use a pair of eights instead.

[lasse]

Time align is most critical in the 300-700Hz range, to the extent that it can be very audible when it's off, so if you lack the ability to time align either by physical placement or electronic means you're better off not crossing over there, choosing your drivers accordingly.

[Music is life]

An application like this is where an active digital system shines. Digital delay can be placed on the mid and tweeter so that all the drivers are time aligned.

Indeed. I might be moving overseas in 2 or 3 years. Speakers, no problem even large horns, right in the container. Electronics often a problem with voltage difference. So that's a lot of amps and stuff, potentially the wrong voltage.

[fpitas]

An application like this is where an active digital system shines. Digital delay can be placed on the mid and tweeter so that all the drivers are time aligned.

[Music is life]

The project for consideration will have a midbass with a 54" path length (about. folded horn with one wide turn). The midrange will be from 14 to 26" depending upon crossover and so then driver choice. The tweeter and midrange will be physically time aligned. The midrange and midbass cannot but will of course need to be in phase at crossover point.
Lowest possible crossover is 225 to 250hz. Hightest possible is 800hz maybe 1000hz.

Thanks for the input.

[billfitzmaurice]

Can you elaborate?

Time align is most critical in the 300-700Hz range, to the extent that it can be very audible when it's off, so if you lack the ability to time align either by physical placement or electronic means you're better off not crossing over there, choosing your drivers accordingly.

[Sydney]

There are too many variables to just pick a crossover frequency. The best crossover frequency will depend on the drivers being used along with the baffle they are on. IMO in a properly designed crossover there really no problematic area if the drivers are up to task.

Yeah and specifics* about the "midrange (horn) and the midbass (horn).

* Horn cutoff frequencies, Dispersion patterns of Horns