"Crossover Design for New Project"

[Altec Best]

[quote=Earl K;1833149]

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 .

That was my thought around 105-106 dB

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 think so too. I believe it was tested a few times to verify accuracy.



[quote]

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 .

I thought it would be the 416's

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

Yes and Thanks Pano for your assistance which I will need for sure !:2thumbsup:

[quote]

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

Yes, But is too big, and as why I want to stick with the 511E won't fit in the corner were the cabinets are going and if I have to align move forward or backward that won't be an option.

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'.

Which I will have to do as I have carpet,draperies,soft furniture, and very thick hard plaster walls.So I guess it would be considered a "soft room"

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 Cd's. 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.

I very rarely listen to the radio anymore except in my car.I have an extensive vinyl collection Lp's 33rpm, Cd's and still some old cassettes and last but not least MP3's I listen to mostly nowadays. Itunes & Napster .I always try to record them at the highest quality level 320 kps as storage will be a non issue.

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.

I guess this will be somewhat trial and error to get them matched properly.

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

I think I still have a pretty good ear.We'll see if I can't pin it down, if not, then I will need some alternatives.

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

Well I would have liked to keep it as simple as possible.But I think I would prefer to design it into the system now then having to add it later.I think it is much easier to do it from the beginning,if it doesn't work I can always remove it.But as I explained to GM awhile back I really like the crack of the snare drum,crash cymbals that hang in the air,instead of dissipating rapidly to me that sounds kind of dull like.The 288 doesn't go high enough to get that sound.And I think I would be unhappy with the result.I don't know how else to explain the sound that I'm talking about that I had explained to GM. It is like a drummer who hits a cymbal and then grabs the cymbal to stop the vibrating of cymbal that is what I liken a tweeter less speaker to unless the HF driver can go high enough like (802G).With a tweet the HF's seem to hang in the air ie:hit cymbal and it keeps radiating sound that floats in the air.:2thumbsup: My speaker has to have that.Along with crisp sweet mid-range(288) that isn't overpowering and tight deep bass is what my goal is.

I'm thinking the tweeter will be the limiting component ( to system sensitivity ) .
- I guess my long standing bias forces me to bet against them holding up their end of the ( spl ) bargain.

My concern as well.How to get the T350 to play loud enough to be heard is a very valid point. With a system over a 100dB efficient will still be very efficient though.I have plenty of power to light them up.

:thankU: Thank You Guys for your advice ! Kind Regards ! :coffeedrinker:

[Panomaniac]

If you add the tweeter in on top with out low passing the 288, then you may have plenty of top end. That's what I do and it works fine for me. A 2.5 way, if you will.

[Altec Best]

If you add the tweeter in on top with out low passing the 288, then you may have plenty of top end. That's what I do and it works fine for me. A 2.5 way, if you will.

Are you talking about just running wires off the 288 terminals with a capacitor and then running them to the T350 ??

[Panomaniac]

Yeah, you can do that. Or you can run them off the main line with their own L-pad and cap. Just don't low pass the 511s, let them roll off naturally at the top. Fill in with the super tweeter.

[bfish]

Hmmm... with the tweet and 511 sharing a common baffle at ~8kHz, (at a wavelength of roughly 1.7 inches), how many full cycles will the desired cymbal decay play on the tweet before the stick comes down on the 511?

Without breaking out a tape measure I come up with roughly around 10.

Can you say... shhtukssse?

Gehsundhit.

[Panomaniac]

Whateverz......

(and who ever said they share a common baffle?)

[Altec Best]

Whateverz......

(and who ever said they share a common baffle?)

Mahalo :2thumbsup:

[bfish]

...(and who ever said they share a common baffle?)

In our last thrilling episode, our hero was backed into a corner, and...

...It would literally only be a few inches from the mouth of the 511...

Followed by an (agreed with) suggestion they be oriented vertically, directly to the outsides of the 511s, next to the wall(s).

Perhaps a bad assumption on my part they'd be mounted on a baffle, so I'll rephrase that to "common plane of being".

Never mind that. The point was it would take a boxfull of caps (or the previosly suggested active delay) to stack up the needed phase delay.

[Panomaniac]

Thank you.

[Earl K]

And I do "CARE" and as why I opened the thread for the open discussion so I could take as much useful info I could.But it seems that there are one or two people following this thread, but for the one or two people for all the wrong reasons !!

But when differences arise and the bickering starts "How can you build Anything like That" once the positives disappear it is time to do the project with what info I have.And take it off line.

John, I think it would be shame to take this project off-line .

Within the overall big picture , there's likely something in it for everyone .

I for one would like to see the FRs ( & IRs posted ) for your 288-8E(s) on your 511Es . Those have never before been posted on the WWW by a DIYer ( at least, that I'm aware of ) ;

Apart from GPAs recent eBay posting , some new data like that would fill a huge void out there .
- There is unfortunately not nearly as much meaningful data available for Altec stuff ( as compared to JBL ) .

Also, I'd like to see an independent FR sweep of that EV "T350" once it's crossed over . There may be some plots out there / but I haven't seen them .

FWIW, I've been waiting for you to get your test gear in order so that you could post some stuff ( under Panos guidance ) // all before I post my 288-8K stuff rigged up with my 110 db/W/M Fostex tweeters . Yes I have tweeters ( many in fact, just not hooked up ) .

Re; Brads concern about the tweeter off-set / delay thing .

- IMHO, once tweeters are crossed above 10K , "wave-length synching" is mostly an exercise in futility . The synch will fall apart at more positions than not .
- JBLs' latest SOTA systems still manage to image very well with UHF "Be" tweeters that are crossed high / even while having mismatched dispersion patterns to the horn below ( 60 deg vs 90 deg ) .
- There's a whole world of UHF physco-acoustics that doesn't necessarily follow the standard "modern" DIY rule-book . "Leading-Edge UHF Disconnect" ( from the main wavefront ) is but one interesting phenomena that shows some people prefer the sound of the UHF wavefront when it's leading the rest of the pack .
- JBLs' big 3-way & 4-way systems have done this for years by the necessity of sharing a common baffle board .

- Anyways , there you go, there are many ways to skin the proverbial cat .

cheers <> Earl K