RAAL tweeter

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winston1156

Re: RAAL tweeter
« Reply #40 on: 4 Jan 2011, 04:48 pm »
Is it possible to put the tweeter proportionately lower in a taller cabinet?  That keeps the listening height acceptable and the tl line is still doable?

DMurphy

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Re: RAAL tweeter
« Reply #41 on: 4 Jan 2011, 04:53 pm »
Is it possible to put the tweeter proportionately lower in a taller cabinet?  That keeps the listening height acceptable and the tl line is still doable?

I think Paul is saying that he could work around the height issue.  You can get into serious diffraction issues if you push the tweeter too far down into the wider section of the cabinet  And I'm not sure it would look all that great. 

Paul K.

Re: RAAL tweeter
« Reply #42 on: 4 Jan 2011, 05:39 pm »
Yes, it's certainly possible to do that and an MTW (or WTM if you prefer) arrangement can work out just fine.  My latest DIY build was exactly that; there's a sealed chamber at the top for the midrange, and below that is larger chamber housing the tweeter and a folded, tapered line for the woofer.  The midrange's center is ~38" above the floor and was the design center for the crossover.


Paul

Is it possible to put the tweeter proportionately lower in a taller cabinet?  That keeps the listening height acceptable and the tl line is still doable?

I think Paul is saying that he could work around the height issue.  You can get into serious diffraction issues if you push the tweeter too far down into the wider section of the cabinet  And I'm not sure it would look all that great.

fsimms

Re: RAAL tweeter
« Reply #43 on: 4 Jan 2011, 05:49 pm »



Nice job! 

I sure do love these discussions as it shows the depth of the thinking that goes into a Salk/Murphy/Bagby/Kittinger design.  :thumb:

Bob





Paul K.

Re: RAAL tweeter
« Reply #44 on: 4 Jan 2011, 05:57 pm »
Thanks, Bob.  The cabinet is finished with a combination of maple and walnut, both veneer and solid hardwood.  The woofer was located near the floor to benefit from that boundary's reinforcement, thus precluding any need for baffle step correction (thanks to that contribution from Jeff Bagby) and its negative effect on system sensitivity.
Paul

[quote author=fsimms
Nice job! 

I sure do love these discussions as it shows the depth of the thinking that goes into a Salk/Murphy/Bagby/Kittinger design.  :thumb:

Bob
[/quote]

DMurphy

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Re: RAAL tweeter
« Reply #45 on: 4 Jan 2011, 06:41 pm »
Very nice indeed.  Ribbon tweeters can present more of a placement issue, since their vertical dispersion isn't as great as a typcial dome.  That's why I prefer to keep the design axis on the tweeter.  Another issue in placing the woofer and mid so far apart is that you have to design for a specific listening distance.  I know that isn't an issue for Paul, because this speaker was designed specifically for a fixed listening position in his room.  I've done a couple of designs with the woofer near the floor, and could optimize response for, say, 3.5 meters with no problem.  But if you move up a little closer, the whole response around the woofer-mid crossover point will change to the point where you will eventually have a huge hole.  It's still a very valid approach, however.  I didn't do it to increase sensitivity per se, but rather to get rid of the floor bounce dip which is always there when you place the woofer up near the midrange.  I would be more reluctant to use a low-mounted woofer in a commercial design because it will have to be used in such a variety of listening positions. 

Vulcan00

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Re: RAAL tweeter
« Reply #46 on: 4 Jan 2011, 07:48 pm »
Any idea of what that might look like?

- Jim

 If I may offer a few general points for a new HT3:

1. Definitely time for a HT3 upgrade:

2. Each driver to have its own enclosure. If a transmission design used then at least the tweeter is separate.

3. Use the smallest enclosure width possible for each driver.

4. The raal enclosure on top. Raal to have a minimum size enclosure/baffle. The Raal enclosure to be configured so that it can move 15 degrees in the vertical direction.

5. I would like to see the HT3 be taller at least as tall as the HT2-Tl. possibly taller with the 0-15 degree vertical movement.

6 I think the enclosure geometry should be simple , in order to keep the build costs as low as possible and allow the wood finishing designs to add the statement of quality and modern refinement.

I am working on a drawing unless , allready I'm off to a impractial start.

winston1156

Re: RAAL tweeter
« Reply #47 on: 4 Jan 2011, 08:21 pm »


Nice lines

fsimms

Re: RAAL tweeter
« Reply #48 on: 4 Jan 2011, 08:40 pm »
New HT3?




Maybe narrower bottom and top with current 10" woofer?

Bob

winston1156

Re: RAAL tweeter
« Reply #49 on: 4 Jan 2011, 08:58 pm »
That is gorgeous!   


Paul K.

Re: RAAL tweeter
« Reply #50 on: 4 Jan 2011, 10:11 pm »
Dennis is correct; the Sonatello design was optimized for my ears while sitting in my sweet-spot recliner 9 feet away.  OTOH the Sonatellos certainly sounded quite good playing music while sitting on the stage at the last Iowa DIY event when I was sitting much further away in the auditorium seats and somewhat below the design axis. 
Paul

Very nice indeed.  Ribbon tweeters can present more of a placement issue, since their vertical dispersion isn't as great as a typcial dome.  That's why I prefer to keep the design axis on the tweeter.  Another issue in placing the woofer and mid so far apart is that you have to design for a specific listening distance.  I know that isn't an issue for Paul, because this speaker was designed specifically for a fixed listening position in his room.  I've done a couple of designs with the woofer near the floor, and could optimize response for, say, 3.5 meters with no problem.  But if you move up a little closer, the whole response around the woofer-mid crossover point will change to the point where you will eventually have a huge hole.  It's still a very valid approach, however.  I didn't do it to increase sensitivity per se, but rather to get rid of the floor bounce dip which is always there when you place the woofer up near the midrange.  I would be more reluctant to use a low-mounted woofer in a commercial design because it will have to be used in such a variety of listening positions.

DMurphy

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Re: RAAL tweeter
« Reply #51 on: 4 Jan 2011, 11:50 pm »
Dennis is correct; the Sonatello design was optimized for my ears while sitting in my sweet-spot recliner 9 feet away.  OTOH the Sonatellos certainly sounded quite good playing music while sitting on the stage at the last Iowa DIY event when I was sitting much further away in the auditorium seats and somewhat below the design axis. 
Paul

The problem occurs when you have to sit closer than the design point.  Once you're at the sweet spot, moving back doesn't change the relative angles of the mid and woofer center points all that much.  But as you get closer, the angle changes substantially, which translates into greater relative differences in the travel times of the woofer and mid outputs.  That translates into changes in the relative phase at the closer listening postion, which creates a null where the two drivers overlap in frequency. 

DMurphy

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Re: RAAL tweeter
« Reply #52 on: 4 Jan 2011, 11:53 pm »
Oh--one other thing.  I know I promised to update my avatar with a more recent pic of the now bigger Ben, but he ate (well, destroyed) my digital camera.  Along with his puppy training manual and most of my collection of sheet music.   

Paul K.

Re: RAAL tweeter
« Reply #53 on: 5 Jan 2011, 12:13 am »
Since sitting further away is apparently okay, it would seem that you could optimize the design for a closer listening distance, say 6 feet, and that would cover most everybody's situation I would think?
Paul

The problem occurs when you have to sit closer than the design point.  Once you're at the sweet spot, moving back doesn't change the relative angles of the mid and woofer center points all that much.  But as you get closer, the angle changes substantially, which translates into greater relative differences in the travel times of the woofer and mid outputs.  That translates into changes in the relative phase at the closer listening postion, which creates a null where the two drivers overlap in frequency.

drab

Re: RAAL tweeter
« Reply #54 on: 5 Jan 2011, 12:27 am »
Oh--one other thing.  I know I promised to update my avatar with a more recent pic of the now bigger Ben, but he ate (well, destroyed) my digital camera.  Along with his puppy training manual and most of my collection of sheet music.

Smart dog! This way he can get out of school, sleep in peace and quiet, and you have no way of documenting any of it!!  :lol: They are so cute at that age.  :thumb:

DMurphy

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Re: RAAL tweeter
« Reply #55 on: 5 Jan 2011, 12:57 am »
Since sitting further away is apparently okay, it would seem that you could optimize the design for a closer listening distance, say 6 feet, and that would cover most everybody's situation I would think?
Paul

It's not all that easy to achieve good results at a close listening position with wide-spaced drivers.  The result would probably be a compromise that wasn't optimal for anyone. 

DMurphy

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Re: RAAL tweeter
« Reply #56 on: 5 Jan 2011, 12:59 am »
Smart dog! This way he can get out of school, sleep in peace and quiet, and you have no way of documenting any of it!!  :lol: They are so cute at that age.  :thumb:

Yeah--real cute.  Some people think Dennis the Menace is cute.  It kind of depends on whether you own the property they destroy.   :?
« Last Edit: 5 Jan 2011, 02:45 am by DMurphy »

Kris

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Re: RAAL tweeter
« Reply #57 on: 5 Jan 2011, 09:30 am »
Separate enclosures make sense, easier to aim and move around, who said the Soundscape has to be the Salk TOTL.  :wink:
I never saw an Internet direct company offer 3 box designs like these:


Nuance

Re: RAAL tweeter
« Reply #58 on: 5 Jan 2011, 04:34 pm »
Oh--one other thing.  I know I promised to update my avatar with a more recent pic of the now bigger Ben, but he ate (well, destroyed) my digital camera.  Along with his puppy training manual and most of my collection of sheet music.   
:duh:  Sorry to hear that, Dennis. 

Nuance

Re: RAAL tweeter
« Reply #59 on: 5 Jan 2011, 04:35 pm »
Separate enclosures make sense, easier to aim and move around, who said the Soundscape has to be the Salk TOTL.  :wink:
I never saw an Internet direct company offer 3 box designs like these:



I like the look of those, for what it's worth.  Very sleek!