250 Boxes

[Titanium Dome]

Here are some TM025 tweeters (in different Waveguides and in cabinets with woofers and networks):

http://cgi.ebay.com/JBL-S26-Studio-S...QQcmdZViewItem

http://cgi.ebay.com/JBL-S38-STUDIO-S...QQcmdZViewItem

[JBLnsince1959]

Thanks guys...the S26 looks like the best candidate....Of course the top curve would have to be cut off and smoothed down...The nice thing about that over the S38 or even the waveguide that comes with the PS series is that the plate ( once cut) can be sunk and the top made flush with the top of the baffle. This should allow less diffractions over all, one would think. One thing I've always wondered about is the "ring" around the EOS waveguide

This is really an excerise in reducing edge and tranducer diffractions, reflections and enclosure vibrations, and if possible to time align the transducers.

As I've thought about this it really all starts at the top with the tweeter...as i said earlier in post 31...

the 250 boxes with their height raises ( excuse the pun) some interesting design considerations for the tweeter .

for example, as we all know the 250/250Ti enclosures have the tweeter housing which aligns the tweeter on a better axis since it's so high. This of course would produce more diffractions (info was confirmed this week )

Interesting tho, the XPL250 prototype does not have this housing. Of course with the XPL series, reducing diffractions was a major design issue and a housing would undo the general design most likely. One wonders how the XPL250 got around the tweeter axis situation, if indeed it did.

When I go putting the PS series transducers into the 250 box I'll be facing the same issues, but this could be more complicated as the EOS waveguide introduces a new set of issues. Unfortunately I've not found any information as to the exact dispersion nature of the EOS waveguide. My concern tho is NOT with the horizonal axis but with the vertical axis, there are only three cases here.
1. the dispersion is "widen" more than normal ( but not as much as the horizonal)
2. It stayed the same
3. It narrowed the vertical dispersion

number 1 would help us ( but how much who knows); number 2 leaves us at ground zero, or the same place as before; number 3 would take us two steps back so to speak.

Interestingly, the European speakers, the Ti5000 and and TL260 have the tweeters flush, but then again, they are not as tall as the 250, nor do i know the angle of the baffle. I'm looking for more exact information about them. It would be nice to find out how tall they are and at what height the tweeters are at.

IF push came to shove, I could always cut off the bottom of the 250 enclosure to drop the tweeter down and if needed extent out the lower back of the 250 box to add volumn.

well, we'll see what happens, I think's it time to go get some chips and dip for the game..

[JBLnsince1959]

The tweeters can be separated from the EOS if you wanted to use different tweeters.

Maybe some time down the road..however, in the beginning I need to keep it as simple as possible by using the same transducers. Using the same transducers reduces any need for major re-design work with the crossovers. I'm going to have enough trouble as it is......I'm not a Giskard

[spkrman57]

....I'm not a Giskard

Nor am I unfortunately!

Ron

[JBLnsince1959]

Just a note to let my friends, those people who have shown an interest in this project and to those who have taken time from their busy lives to help..( much appreicated, thanks)

the project has to be put off again

Unfortunately my lady had some NEW problems starting 4 or 5 weeks ago and now she has to go back into the hospital for another operation the 28th of this month. ( she had two operations in August) I've chosen to just spend my time with her, not be selfish and just do my suff ( which I can easily do - ha)


I haven't on here much because of this...so if i'm not back soon...wish all of you a great holiday season..

enjoy the sounds.......

take care
rick

[Robh3606]

Hello Rick

Hope all goes well with your lady.

Rob

[Rolf]

Rick!

Your friends here in Norway wish you and your wife, and other family the best.

Don't take any trouble in advance. (hope I got this right)

We love you.

Ruth& Rolf in Norway.

[JBLnsince1959]

thanks guys, much appreciated...you've seen me before and you've seen Whit of course...but never her...well here we are, all dressed up and no where to go...

[jblsound]

Thanks guys...This is really an excerise in reducing edge and tranducer diffractions, reflections and enclosure vibrations, and if possible to time align the transducers.

As I've thought about this it really all starts at the top with the tweeter...as i said earlier in post 31...

for example, as we all know the 250/250Ti enclosures have the tweeter housing which aligns the tweeter on a better axis since it's so high. This of course would produce more diffractions (info was confirmed this week )

Interesting tho, the XPL250 prototype does not have this housing. Of course with the XPL series, reducing diffractions was a major design issue and a housing would undo the general design most likely. One wonders how the XPL250 got around the tweeter axis situation, if indeed it did.

When I go putting the PS series transducers into the 250 box I'll be facing the same issues, but this could be more complicated as the EOS waveguide introduces a new set of issues. Unfortunately I've not found any information as to the exact dispersion nature of the EOS waveguide. My concern tho is NOT with the horizonal axis but with the vertical axis, there are only three cases here.
1. the dispersion is "widen" more than normal ( but not as much as the horizonal)
2. It stayed the same
3. It narrowed the vertical dispersion

number 1 would help us ( but how much who knows); number 2 leaves us at ground zero, or the same place as before; number 3 would take us two steps back so to speak.

IF push came to shove, I could always cut off the bottom of the 250 enclosure to drop the tweeter down and if needed extent out the lower back of the 250 box to add volumn.

well, we'll see what happens, I think's it time to go get some chips and dip for the game..

I just looked at the TL 260, its 47" tall, is that about the same as the 250?
In comparision, my PT800/SUB1500 stack is 46.75" with the tweeter @ 42.5". Not sure how that compares with the PT800/PS1400 stack.

Of coarse the TL 260 uses drivers more like the Studio L series, that being Polyplas.
And the array is different from the 250; being 3/4" mylar, 1" Ti, 4" poly, 6" poly, 12" poly.
The tweeters are in the waveguides w/o the baffle offset.
Not sure, but I think the use of the waveguides eliminates any diffractions, as they control the radiating pattern.

[JBLnsince1959]

I just looked at the TL 260, its 47" tall, is that about the same as the 250?
In comparision, my PT800/SUB1500 stack is 46.75" with the tweeter @ 42.5". Not sure how that compares with the PT800/PS1400 stack.

Of coarse the TL 260 uses drivers more like the Studio L series, that being Polyplas.
And the array is different from the 250; being 3/4" mylar, 1" Ti, 4" poly, 6" poly, 12" poly.
The tweeters are in the waveguides w/o the baffle offset.
Not sure, but I think the use of the waveguides eliminates any diffractions, as they control the radiating pattern.

To be honest, I've forgotten most of the details, I'll have to re-read my notes on this. As I've said before personal matters ( and business) has consumed most of my time and thinking over the last 2 years.

First thing I'll do when I get serious on this is to do some "real" numbers so we know exactly what we are dealing with. So far it's mostly just been me "Thinking out loud" on the forum and doing some half-ass quicky stuff.

When I'm doing this for real, there will be a new thread in DIY forum. Who knows, maybe someone will beat me to it and save me all the design work ( ha)

thanks for the interest...

rick

[hjames]

thanks guys, much appreciated...you've seen me before and you've seen Whit of course...but never her...well here we are, all dressed up and no where to go...

Nice to see you both - great picture!
Hope all the problems have resolved themselves and hope she is doing better!
Speakers is speakers, but family ... is all important!

[JBLnsince1959]

Nice to see you both - great picture!
Hope all the problems have resolved themselves and hope she is doing better!
Speakers is speakers, but family ... is all important!

Thanks.. it means a lot. Yes, she's all better now - so that means she can now tell me what to do ( ha)

It's been a rocky ride for a long time, even Whit( My GS) had some operations the last year. Hopefully I can get back into some form of a normal life here. I have to admit, my quota of JBL'n is next to zero for a long time and my ears are feeling deprived... not mention the many projects that have been set aside for myself and other people.

all the best and thanks again