"Crossover Design for New Project"

You're welcome! All the credit goes to EV though for setting up that archive awhile back.

Well, a 288 attached to a long straight tube is around 137 dB/W/m, but as its shape starts expanding it's efficiency drops to where on a 329A horn it's down to ~110.7 dB/W/m and an 802 on a 511 is only good for ~107 dB/W/m, so I'll be surprised if a 288 coupled to a truncated 511 can do much over a 100 dB/W/m.

In the XO's BW, dual 416-8Bs in parallel should be around 103-104 dB/2.83 V/m, so it will be interesting to see if the 511E can keep up.

GM

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Originally Posted by GM

In the XO's BW, dual 416-8Bs in parallel should be around 103-104 dB/2.83 V/m, so it will be interesting to see if the 511E can keep up.

GM

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I have a pair of 288's hooked up to 1005's right now if the 511E's perform close to them I would say no problem without breaking a sweat.I am so looking forward to this experiment with measuring the 511E's/288's


How close in sensitivity do the T350,288,and 416's have to be for there not to be a big problem.If the mis-matches are great I would need some sort of modeling software correct ?

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Originally Posted by GM

,,,,,snip,,,,,and an 802 on a 511 is only good for ~107 dB/W/m, so I'll be surprised if a 288 coupled to a truncated 511 can do much over a 100 dB/W/m.,,,,,snip

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I feel you're being overly pessimistic about the net efficiency of the 511E with a 288-8E driver attached .

I'd be quite surprised if its much less than 105-107 db/W/m .

http://www.hostboard.com/forums/hbmc.../2010/08/1.png

Call me gullible, but I'm willing to believe that GPAs 511E plot was done with some due diligence to the implementation of measurement standards .



Re; the efficiency of the EV T350 .

- I'll be very surprised if that 109 db figure still stands after everything below 8K is excluded .

<> cheers

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Originally Posted by Altec Best

How close in sensitivity do the T350,288,and 416's have to be for there not to be a big problem.If the mismatches are great I would need some sort of modeling software correct ?

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No matter what the actual sensitivities are / you're going to have to pad some component(s) down to match up with the component having the lowest sensitivity .

How much padding will have to be determined after you take some FR readings of the system ( hooked up to some preliminary networks) .

<> cheers

Yep. I'll be helping A.B. with the crossover, and that's exactly what we will be doing. :2thumbsup:

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Originally Posted by Altec Best

I have a pair of 288's hooked up to 1005's right now.........

How close in sensitivity do the T350,288,and 416's have to be for there not to be a big problem.

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Originally Posted by Altec Best

If the mis-matches are great I would need some sort of modeling software correct?

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The 1005 is a longer/larger horn, so should be a good match to dual 416s once EQ'd.

In theory you want the system's response to be ruler flat from at least 20-20 kHz (or whatever the system's source available low/high F10 BW is) throughout the listening area which of course is extremely hard to do even in an acoustically ideal room and if max efficiency/SQ is required, then all the speaker system's (drivers+XOs) efficiencies must be matched in the sense that they can attain the desired dynamic headroom at low distortion at max desired average SPL.

From this we see that to do a proper system design requires knowing the room's acoustics and the max BW/dynamic headroom of the source(s), otherwise you design for the max your budget can afford in components, gross bulk and then EQ it to be as flat as practical over a fairly narrow 'sweet spot'.

FWIW, the acoustic power structure of the *recorded* music I've measured using a 1/3rd octave RTA's peak hold feature, max dynamic headroom is required in the ~250-500 Hz BW (+30 dB, clipped!) for a few symphony CDs and ~32-96 Hz (up to +32 dB!) for a couple of pipe organ CDs. The rest peak out at +24 dB in the ~40-1 kHz BW. I apparently no longer have the various individual source's data, so if you only listen to FM radio and/or pre-mid '70s vinyl and/or 78 rpm LPs, designing to any of these would seem overkill by the vast majority, though I just view it as that much lower a distortion level.

WRT XO or any other aspect of an audio system's design, the more powerful the software and measuring system, the less time required to dial it in to a target response once you've enough experience with them. Me, I didn't even have a RTA until well after my peak building years, so am strictly 'old school'/'dinosaur' for the most part.

Anyway, based solely on my limited measurements and using a worst case scenario, either the room's acoustic gain and desired F10 or how much EQ is required to flatten the T350 out to 20 kHz or its desired F10 will set system sensitivity, so don't have a clue how closely matched the components ideally need to be.

That, or a good 'ear' for matching tonal balance to within +/-3 dB over at least the ~40-15 kHz BW.

GM

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Originally Posted by Earl K

Call me gullible, but I'm willing to believe that GPAs 511E plot was done with some due diligence to the implementation of measurement standards .

I'd be quite surprised if its much less than 105-107 db/W/m .

Re; the efficiency of the EV T350 - I'll be very surprised if that 109 db figure still stands after everything below 8K is excluded .

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Cool, thanks!

Call me 'old school', but to properly XO a super tweeter to it requires that it be flattened based on its HF extension which puts it much closer to 100 dB than 105 dB.

Agreed, all compression horn gain BW efficiencies are limited to only a few octaves at most.

GN

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Originally Posted by GM

Cool, thanks!

Call me 'old school', but to properly XO a super tweeter to it requires that it be flattened based on its HF extension which puts it much closer to 100 dB than 105 dB.

Agreed, all compression horn gain BW efficiencies are limited to only a few octaves at most.

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- Okay, I now see where you're coming from .

- I happen to agree with that practice ( flattening out the 288/511 ) before crossing into the tweeter . So you're right, after some midrange suppression, the horn will be around 100 db .

I think we're in agreement that system sensitivity is going to be limited to just over a 100 db ( we just might not agree on which component should shoulder the blame ).

Not being much of a tweeter guy / I guess I naturally blame them for all the ills in the world ;)


<> cheers

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Originally Posted by Earl K

- ( we just might not agree on which component should shoulder the blame ).

Not being much of a tweeter guy / I guess I naturally blame them for all the ills in the world

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OK, which one do you think it will be and why?

I wasn't either until relatively inexpensive digital delay became available and even then only for low noise CD, DVD that has significant output to >15 kHz.

GM

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Originally Posted by GM

OK, which one do you think it will be and why?

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I'm thinking the tweeter will be the limiting component ( to system sensitivety ) .

- Based on my assumption of 1 octave of useful BandWidth ( 8 to 16K ) ;

(i) I figure, getting rid of information below 8K will toss away a good 6 db of that official sensitvity figure .

(ii) Insertion loss of a higher order ( 3 pole ) UHF network will steal another db or more .

(iii) I'm guessing that above 8K the T350s impedance curve actually does become a curve and rises above 10 ohms / putting the tweeter at a disadvantage for equal current draw when compared to the midband response of the horn driver . This might also cost the tweeter a couple of db in the race to be heard .

- Granted , all three of the above scenarios need to come true to fatally disadvantge the tweeter ( compared to the horn ) .
- I guess my long standing bias forces me to bet against them holding up their end of the ( spl ) bargain.

<. cheers