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Old 29th September 2007, 01:51 AM   #41
MJK is offline MJK  United States
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salas,

I know who Tom Danley is and have read some of his posts in the past. I agree with some of the things he states and disagree with others.

But returning to your post, I still disagree with your entire post. It would appear you have not used the driver or heard it in a system like I have designed, actually built, and was listening to less than an hour ago. Yet you make recommendations for altering the driver based on speculation. I am not going to waste any more of my time replying to you, we can agree to disagree.
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Old 29th September 2007, 02:02 AM   #42
Salas is online now Salas  Greece
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This is quite a negative attitude. I proposed an experiment. You can decline it and thats all. But your stating its an outright ''terrible'' idea out of hand, doesn't come from someone who did the experiment either. Remains a speculation too. I wrote ''I think'' not ''I know''.
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Old 30th September 2007, 09:50 AM   #43
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Quote:
Originally posted by BHD
My parts are ordered... anyone else have them on the way?

I'm really curious to see your project! Now I'm on a BIB but this design seems a great next project......
These forums are so #$^&*!!!! BIBs, Curvy Changs, Suzy C, OBs! Wish I have plenty time and .....money
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Old 1st October 2007, 01:50 PM   #44
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Default Martin, just a couple of questions....

After exploring the OB speaker type and being stupid enough to expose my kids to them, my eldest daughter has asked for a room friendly OB speaker pair for her new apartment. My JELabs style OBs simply take up too much real estate on the floor.

I did read through your quite excellent article. I enjoyed it very much.

One question regarding the baffle enters my mind however. Is the baffle canted slightly rearward or is it purely vertical? If it is canted rearward slightly, the CG of the baffle/loudspeaker assembly would be more stable than if vertical. Your thoughts?

This is of course more of a paractical consideration rather than one designed to create a time coherent design via a front that is sloped vs one that is not.

Also would "wings" such as those used in the Visaton No Box design be suitable for use? Thanks for your excellent article and continued design work.

With the Cdn dollar at par nowadays, it would make sense to purchase the drivers soon (before our dollar plumets, as history has typically illustrated)

stew
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Old 1st October 2007, 03:50 PM   #45
sreten is offline sreten  United Kingdom
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Default Re: Martin, just a couple of questions....

Quote:
Originally posted by Nanook


One question regarding the baffle enters my mind however. Is the baffle canted slightly rearward or is it purely vertical? If it is canted rearward slightly, the CG of the baffle/loudspeaker assembly would be more stable than if vertical. Your thoughts?

32" driver height at ear height implies vertical, its just a study....
A full design would likely consider such practical considerations
as for a start an angled bafffle would allow lower overall hieght.


This is of course more of a practical consideration rather than one designed to create a time coherent design via a front that is sloped vs one that is not.

Also would "wings" such as those used in the Visaton No Box design be suitable for use? Thanks for your excellent article and continued design work.

They would probably work in reducing overall width somewhat but
again as it a "paper design exercise" they cannot be modeled with
the "Edge" tool used. Such details are not the point of the article.
The point is to illustrate a number of general principles.


stew
Great article BTW. In practise I'd chuck in a supertweeter for
top octave dispersion, but its a far better starting point for
a decently flat 8 ohm widerange driver than build and hope.

/sreten.
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Old 1st October 2007, 05:00 PM   #46
sreten is offline sreten  United Kingdom
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Hi,

Well some net surfing produced not a single measured frequency
response of the FE103 - which is not a good thing because the
Fostex curves cannot be trusted :

See : http://www.troelsgravesen.dk/FE126E.htm

Some measured data on the FE103 would be useful .....

/sreten.
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Old 1st October 2007, 05:32 PM   #47
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Quote:
I'm really curious to see your project! Now I'm on a BIB but this design seems a great next project......
I should be getting the parts this week and will be putting it together this weekend. I'll post my impressions.

Quote:
In practise I'd chuck in a supertweeter for
top octave dispersion, but its a far better starting point for
a decently flat 8 ohm widerange driver than build and hope.
One thing that appeals to me about this design is its inherent simplicity and ease of construction. Once the drivers are broken in and I'm more accustomed to their sound, I'll order up a pair of phase plugs from Planet-10, that should (in theory) help with the HF dispersion. Again, I'll be sure to post my impressions. If I like the sound, more mods will follow (enable, mamboni, etc...).

I have a question about the baffle, though. Would it be a good idea to slant the outside edge of the baffle (think apogee speakers)? I would think this should help break up resonant modes. Opinions?

I'd also like to thank Martin for taking the time and for the effort to put this project out for us to try. I'd love to see a design using two Alpha 15A's and a B200 per side, I bet that'd rock! But for now, the anticipation is killing me, it's like Christmas when I was a kid!



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Old 1st October 2007, 06:15 PM   #48
Nanook is offline Nanook  Canada
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Default sreten...and MJK too

er... sreten, I was asking MJK. However your thoughts and comments are appreciated.

Your thoughts are in itallics? The wings I am refering to are more so baffle "legs" or whatever one might call the side panels of something like the Visaton NoBox design.

My experience with the JELabs/Stereo Sound OBs indicate that a full width "top shelf" and a side wing or "upright" brace between the two also helps bass, although I have no measurements to prove to what extent.

38" X 20" baffles appear friendly enough, as long as the woofer magnetic fields don't kill a tv from 3' or 4' away.
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Old 1st October 2007, 11:47 PM   #49
MJK is offline MJK  United States
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Default Re: Martin, just a couple of questions....

Quote:
Originally posted by Nanook
One question regarding the baffle enters my mind however. Is the baffle canted slightly rearward or is it purely vertical? If it is canted rearward slightly, the CG of the baffle/loudspeaker assembly would be more stable than if vertical. Your thoughts?

This is of course more of a paractical consideration rather than one designed to create a time coherent design via a front that is sloped vs one that is not.

Also would "wings" such as those used in the Visaton No Box design be suitable for use? Thanks for your excellent article and continued design work.
Hi Stew,

Thanks for the positive feedback. It was a fun article to write, putting the curves together and feeling the lightbulb above my head flicker as I began to understand the relationships that produced the plotted responses has really helped me see OB design trade-offs more clearly. While there are many other ways to make an OB system work well, I liked using the acoustic properties of the baffle and the relationships between the driver SPL levels to produce a flat response.

Tilting the baffle back or adding some small side and top wings, like the Visaton design, seem like decent ideas but I have no idea how significant a change in the SPL response they will produce. Probably not much if I had to guess. I had envisioned a baffle made of two layers of 3/4 inch think plywood with a damping material sandwiched for a total thickness between 1.5 and 1.75 inches. Adding a flat piece of plywood to the bottom protruding in the front and back to form a foot and I was done with the design. Again, simple and cheap.

Hope that helps,
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Old 1st October 2007, 11:52 PM   #50
MJK is offline MJK  United States
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Default Re: Re: Martin, just a couple of questions....

Quote:
Originally posted by sreten
Great article BTW. In practise I'd chuck in a supertweeter for
top octave dispersion, but its a far better starting point for
a decently flat 8 ohm widerange driver than build and hope.
Thanks. An inexpesive super tweeter might help but I would probably give a listen first before making the addition. I use the Fostex FT17H on my Lowther system and it does fill in the very top end nicely.
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