Does anyone know how to calculate the amount of delay needed to time-align components? I would imagine we're converting inches to milliseconds!
I think Its an oft overlooked area that reaps significant aural benefit. Also...can the delay be accomplished by passive means? Thanks.
Speed of sound at sea level is about 1,116 feet per second, so it works out to be about 1.1 ft per millisecond. Most people just use 1 foot/ms.Originally Posted by rich carnese
Sure, just move one speaker forward or backwards accordingly.
13.56 in/ms
Not that I know of.
But be mindful that passive crossovers induce measurable "delay" between drivers - this particularly impacts the woofer (IIRC, this is imparted by the inductor in the HPF, but my knowledge of crossover design is admittedly limited. I'm a user.... Someone no doubt will correct me.)
bo
"Indeed, not!!"
Yes it can be done passively. P.A.S. has done it extensively with Time Offset Correction*, and so did UREI with Time-Align* monitors.
It has to do with calculating the crossover filters' phase delay of physically offset voicecoils.
You won't find the formulas to calculate such passive filter wizardry here but you might find it in a copy of LEAP or some other filter design software.
Edgewound...JBL Pro Authorized...since 1988
Upland Loudspeaker Service, Upland, CA
All passive crossover exhibit a phase shift along with affecting amplitude. The trick would be to use that phase shift to "align" the drivers. As to how to make this happen, I don't know....Urei used a crossover designed by E.M.Long to time align the 604.
I have seen the use of so-called "all pass" crossovers (active analog) that exhibit time delay (through pase shifting i believe)....but, this obviously doesn't meet your passive requirement.
Frederick
Yea, exactly my quandary...
bo
"Indeed, not!!"
Divide the wavelength at XO by the percent of phase shift where 360 degrees = 100%
(Or should I say multiply...? You get the picture.)
Handy-dandy wavelength calculator;
http://www.mcsquared.com/wavelength.htm
Example;
With 90 degrees shift (25% of 360) at 800Hz (16.95")
16.95" x 0.25 = 4.2375" offset
YES , Lincoln Walsh designed it into his full range driver. Works very well , thank you.
Some kind of happiness is measured out in miles
Yea, but to know what is going on, he'd need to measure the speaker output, and iterate the design.
bo
"Indeed, not!!"
It is either measurements or true guesswork.
I advise you to do some extensive reading. There are some treatment of this topic in "Loudspeaker Design Cookbook". Since the topic is compound you'll find it is covered in several chapters...
Johnny Haugen Sørgård
Thanks for the info. I cant physically move the components because it is a coaxial unit. I want to use active crossovers and the ones I'v seen with any kind of delay built in are like the DBX and BBE. and they're really designed for PA use. As posted elsewhere Marchand Electronics makes some nice stuff but makes no provision for time-align. Does anyone have experience with the PA style speaker management units at home? Thanks
Well, you know how we all feel about using a speaker designed for “pro use” in the home environment.
Seriously, a friend of mine has had excellent results with some of the newer generation, PA style active units with room correction, parametric EQ, etc. This is route I would take. You may have a time aligned speaker, and without the proper acoustic environment- it wouldn't be fully utilized. A unit that "compensates" for some of the most detrimental anomalies will probably give you the best performance per dollar/time ratio especially when you consider the complexity of aligning via passive means. Rather than focusing on how the drivers are time aligned from a mic positioned in an anechoic chamber with respect to the baffle- you can mic the sweet spot of your listening position in your own room.
Then there’s the parametric EQ you gain. Bo can tell you how important SmartLive software has been for home use. Ken P can tell you how vital the DEQX units have been for home use. What I’m driving at is the parametric EQ performance alone is worth the admission. Really good parametric EQ with on-the-fly adjustability, combined with a means to measure it will probably yield higher performance than a time aligned speaker in an average (acoustically challenged) environment.
All of the above aside- you can run your drivers with steep order crossover slopes (up to 300db/oct in some cases) at infinitely adjustable points.
The newest ones exhibit very low distortion and have a graveyard quiet noise floor. If you like to modify, there is plenty of upgradeability inherent in them. Bypassing the screens, and unused ins/outs is just the start…
So, I say..
Go for it!!
Nate.
The plot thickens - key characters are kept hidden from the readers!
Anyway, my L-Acoustics are coaxial and I can tell you the "delay" between elements, when run active, is very very small - by design. You may have no real concern. But until you reveal what stuff you are using and talking about, we can be only moderately helpful.
Don't leave out the xta, KT and BSS units - all higher quality than those you mention. Were it me, and I was going this route, I would not scrimp on cost - it will really impact the quality of the A/D - D/A converters and all the rest of the internals. That would be a bad idea.
As posted elsewhere, I've used the KT DN9848 for over three-years in my SR and have no issues with it. It is a truly amazing unit. My most recent experience was of a few days-time tuning my system for the new L-Acoustics. With Smaart I modelled a preset of PEQ filters (up to 6 on each output), delays and gain that is so darn flat, I've since gone through 5 shows and not touched my outboard graphic "safety net". Much of this is the quality of the L-Acoustics, but the power lies in the DSP.
When I set-up my SR system and do the routine tests and listening pre-show, it is suprisingly high quality - distractingly so. IMO, if you went with one of these in the home, you would be pleased. But, that opinion contains no knowledge of your system, listening environment or much else - it is merely an appraisal of the KT DSP in my experience.
I do not use the DN9848 at home, because I'm damned pleased with the sound of the 4345's run biamped (and backwards...), old-school. Surely it is a jumble phase-wise, but it is by design. Come to think of it, I never even bothered with Impulse tests in Smaart - since I wasn't going to try and correct it, it was superfluous data to me.
bo
"Indeed, not!!"
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