It totally depends on the actual drivers, waveguides etc. For example typical hgh-frequency horn's acoustical center is furter back than of a typical cone woofer's if both are placed on the same front baffle buth a typical bare dome tweeter's acoustical center is forward of a typical cone woofer's.
Typically 5/8" to 3/4", approximate for small woofers, and dome tweeters.
Here's some information I gathered a while ago. The first few paragraphs are a response from Ben (@wolf_teeth) when I asked him. The "Jeff" Ben mentions is Jeff Bagby.
Thanks for nice answers.
What is more correct is to talk about the 'acoustical centers'.
I guess this understood.
What I get from your answers this distance should be between 15 and 25 mm.
18 mm is a good mean value. Will mean 52 uSec delay.
System in my mind is 1" tweeter and 7" wooofer in a two-way.
Last edited:
The pioneer's conclusions presumably from both anechoic (Bell Labs) and free space measurements (~84"h*80w*40"d reflex horn w/wings).
This X-over design document from TI has the info and formulas in section 2.4 starting at the bottom of page 12.
Thanks. Sorry, I haven't actually applied the info in any of my projects yet.
I just recently became aware of the paper, from a seemingly credible source, and passed it on.
Best success!
I just recently became aware of the paper, from a seemingly credible source, and passed it on.
Best success!
"forward of woofer"? No. From one of the references:
"Practically, what this means is that one will have to offset the tweeter (i.e. move it back)."
The tweeter is smaller and faster so it needs to be set back.
See: https://en.wikipedia.org/wiki/Loudspeaker_time_alignment
"Practically, what this means is that one will have to offset the tweeter (i.e. move it back)."
The tweeter is smaller and faster so it needs to be set back.
See: https://en.wikipedia.org/wiki/Loudspeaker_time_alignment
Agree great paper !
It is a lot more because it is not the same delay when you use a passive crossover and an active crossover with the same drivers. I don't know really why.
I notice the delay is not the same with a passive crossover and an active crossover.
For 8" + 1" It is near 6/6.5cm. But I recommend to measure the distance with an acoustical measurement system.
IMHO how to find acoustic center offset (at any frequency) should be a homework exercise -- one-liner -- using only a tone generator (and the ruler). Once this has been done for each driver and they are physically offset time-aligned, the XO can then be (more simply) designed and similarly adjusted to ensure phase-alignment around each overlap region, for coherent sound, best transcients and deep soundstage.
Please use our search function: LX acoustic center, by wchang (method in the summary, and many applications). LX is only the technique; the speaker can be stepped-baffle. Or, the OP can DSP the delay given the measured offsets.
Please use our search function: LX acoustic center, by wchang (method in the summary, and many applications). LX is only the technique; the speaker can be stepped-baffle. Or, the OP can DSP the delay given the measured offsets.
Last edited:
Not precisely, but 33mm +/- 5 (even 1mm off, 9° phase for 8.5khz, makes a significant audible difference by the LX method).
Last edited:
My experience is about 1.2" given a 5" woofer and dome/ring radiator using interferometry (moving delay in simulator until they match)