Horn recommendation

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Originally Posted by Cut-Throat

I replaced my Khorn Midranges with an Altec 1005B horn and 288-16K driver. takes the Khorn to a level that is --- "I don't look for speakers anymore".
http://www.hostboard.com/forums/hbmc...g?t=1287453560
Crossovers can be tweaked easily also.

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- Anecdotal evidence ( as above ) suggests that you'll find happiness using the 500hz series multicells ( even down to 400 hz ) as long as you use the higher compliance diaphragms ( ie; 288s ) in original style 288 bodies ( with the original longer snout , as compared to GPAs sawed-off jobies ) .
- I suspect that "higher compliance" also rules out the useage of 290/292s .
- 1005s can have a few cells blocked with ( fiberglass, lambs-wool, HD dacron ) to control directivety to address GMs' concerns on pattern-control .
- ie; buy any 500hz multicell that suits you ( even if it has a few too many cells for properly controlled dispersion within your current room ) .


<> EarlK

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Originally Posted by EarlK

,,,snip,,,,,in original style 288 bodies ( with the original longer snout , as compared to GPAs sawed-off jobies ) .

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This may strike some as an odd statement, but I do have a long memory for such seeming triviality .

Taken from here in 2006 .

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Originally Posted by Todd

Dr. John K. Hilliard told me, as have several other Altec acoustical engineers, that the large pot casting, especially on the big Altec drivers, lowers the mechanical resonance to a point below the lowest usable crossovers. Without it, the 288/299's sound AWFUL by comparison!

Bill's working on getting one for GPA's big drivers...

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Originally Posted by cclark65

This is directly from one of the current Altec Professional Engineers:

"The 399-8A and 399-16A drivers are shortened 299?s. We removed the extended snout and made the driver only 3.9? deep. The change also removed approximately 10lbs of weight! Functionally the 399 drivers are 1.5dB down between 500Hz and 800Hz when compared to the 299. We view this loss as acceptable because most sound system designs are using large format drivers above 800Hz. "

The reduction in the size of the driver for professional use normally does have the crossover higher these days, due to higher powered bass and midrange drivers, and bigger amps. However, for home users that want to run them lower, it's not going to work properly.

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Originally Posted by Todd

Yes, but even if you crossover at 800-1000 Hz, there is still sufficient acoustic energy being generated below such a high point that the problem you hear in JBL drivers, for example, shows up - that "sssth" "sssth", which is a non=harmonic distortion caused by the subharmonic's setting themselves up as fundamentals - which just makes the drivers difficult to listen to without a LOT of electronic (READ: unnatural) correction.

ALPro put that in their spec sheets because they had to come up with SOME excuse for the pancake drivers. It's NOT an acceptable compromise, because DIRECT output isn't all we're talking about here...

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Originally Posted by Todd

OK, here's the deal:

1. The large pot casting on the large format drivers reduces the mechanical resonance to a point way below the lowest USABLE crossover.

2. This results in NO audible sub-harmonic distortion being generated by the mechanical portion of the driver.

3. If you remove the large pot casting, as Bill Hayes and his team at Altec did when they were developing the ceramic 288's in Anaheim, it sounds AWFUL! This is because the large internal volume, as Jerry Hubbard will tell you also (they found out the same thing in OKC when they were looking to improve the 288 and came up with the 299), is essential to preventing subharmonic's from setting themselves up as fundamental's and generating all kinds of ugly distortion.

In short, YES the large format drivers with the large pot casting DO have less distortion - irrespective of their crossover frequency or the bandwidth they are being asked to produce - than do the IDENTICAL units WITHOUT the pot casting.

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<> cheers

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Originally Posted by Earl K

- ...in original style 288 bodies ( with the original longer snout , as compared to GPAs sawed-off jobies ) .
<> EarlK

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Unless you buy gpa vintage series drivers, such as the 288h, which is a gpa product?

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Originally Posted by Earl K

- Anecdotal evidence ( as above ) suggests that you'll find happiness using the 500hz series multicells ( even down to 400 hz ) as long as you use the higher compliance diaphragms ( ie; 288s ) in original style 288 bodies ( with the original longer snout , as compared to GPAs sawed-off jobies ) .
- I suspect that "higher compliance" also rules out the useage of 290/292s .
- 1005s can have a few cells blocked with ( fiberglass, lambs-wool, HD dacron ) to control directivety to address GMs' concerns on pattern-control .
- ie; buy any 500hz multicell that suits you ( even if it has a few too many cells for properly controlled dispersion within your current room ) .


<> EarlK

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Thanks Earl,
I find it difficult to grasp some of the technical info given here, so thanks for spelling it out.
So the 805's are the go for my application....now what about those drivers. Obviously from your post I need 288's & not 290's. I assume that all the different variations of 288's are still called just 288's.....when you say "longer snout" do you mean that the body is physically larger? than other 288's?
Would you have any photos to show the difference or point me in the right direction to see some?

Many thanks,
John

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Originally Posted by John

Thanks Earl,
I find it difficult to grasp some of the technical info given here, so thanks for spelling it out.
So the 805's are the go for my application....now what about those drivers. Obviously from your post I need 288's & not 290's. I assume that all the different variations of 288's are still called just 288's.....when you say "longer snout" do you mean that the body is physically larger? than other 288's?
Would you have any photos to show the difference or point me in the right direction to see some?

Many thanks,
John

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Hi John,

Not so fast partner ! Be carefull in how you interpret my posts . If I was in your ( admitted ) less than fully informed situation , I would take this all quite slow for the time being ( & give the educational process months, not minutes ).

I've made a suggestion ( based on someone elses experience / not my own ) that the 500 hz multicells may get to the desired 400hz point ( with a little coaxing ) under specific conditions ( as long as one somewhat mimics "Cut-Throats" setup ) .

What's needed now is for someone to setup to the plate and provide some solid measurements to see if those choices can actually fit the bill .

There are some here ( though not me ) who own these multicells ( as well as 288 drivers )and could in fact provide the necessary proof "of concept" ( if they were so motivated ) . This may happen later than sooner /so be patient .

And yes, I'm talking about the 288 series of drivers not the newer 3xx series .
- All the 288 series have a pretty similar snout ( pot casting ) .

<> cheers

Then would the older 290 series with 288 'frams be OK? They are the same motor and phase plug, right?

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Originally Posted by Earl K

Hi John,

Not so fast partner ! Be carefull in how you interpret my posts . If I was in your ( admitted ) less than fully informed situation , I would take this all quite slow for the time being ( & give the educational process months, not minutes ).

I've made a suggestion ( based on someone elses experience / not my own ) that the 500 hz multicells may get to the desired 400hz point ( with a little coaxing ) under specific conditions ( as long as one somewhat mimics "Cut-Throats" setup ) .

What's needed now is for someone to setup to the plate and provide some solid measurements to see if those choices can actually fit the bill .

There are some here ( though not me ) who own these multicells ( as well as 288 drivers )and could in fact provide the necessary proof "of concept" ( if they were so motivated ) . This may happen later than sooner /so be patient .

And yes, I'm talking about the 288 series of drivers not the newer 3xx series .
- All the 288 series have a pretty similar snout ( pot casting ) .

<> cheers

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Not sure I understand why I need to "take this all quite slow for the time being". I suppose I thought that quite a few people would have used this combination of components before & could offer advice.

Am I upsetting some forum members here by wanting to know the best combination of Altec midrange for my application? If so, that was certainly not the case. What I'm after is the combination that offers me the best mid range presentation within the constraints of my crossover settings.
I appreciate you may not want to give your recommendation to a set of components that is not validated to perform to my requirements. I suppose I'm looking to see if anyone has used this set up in similar conditions & how they found the results....as Cut Throat has done.

I appreciate your comments on the 288 drivers, as that clears that up for me.

Hopefully others who have this set up can post their opinions.
Thanks,
John

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Originally Posted by Panomaniac

Then would the older 290 series with 288 'frams be OK? They are the same motor and phase plug, right?

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290s and 288s are very similar bodies, but the diaphragms aren't interchangable. Different gap dimensions.

Oops! Sorry. I meant 291 and 288 are the same motor. (not 290) :(

I have an opportunity to audition a pair of 805 multicells fitted with 288-16 drivers on my system. Should be able to pick them up within the next couple of weeks & I'll give you my thoughts on these. Should be interesting.