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Old 13th January 2011, 12:55 AM   #111
db6546 is offline db6546  United States
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Zilla - I don't have a pair up and running. I built this box to use as a test mule.

GM - I tried the .98 tweak. It helped some, but it still had too much cupped sound for my taste. I also flexed that outer ring on the whizzer, but that didn't do much either. I guess should have tried kneading the whole whizzer before cutting.

Today I removed the driver and tested it with my WT3. Fs is now 74 Hz and Qts is .54. Based on the size of the box, and that I'll need help on both ends, I'm going to move on from this project.
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Old 13th January 2011, 12:00 PM   #112
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Quote:
Originally Posted by Godzilla View Post
JRKO, i had an idea (a sketch) for your speaker but can't share until i get in front of a scanner. Would you rather go wider or deeper? The Focal design is very cool too. Would you angle the boxes in the same way? I think it would be great to put the 12lta on top and angle it down like that.
I'm going for wider that deep as this will better suit our lounge.

If I went the focal route then I would have the 12LTA angled down. I need to get spousal approval for that. If not then the tweeter will end up on one of those stands made of dowel that fostex show their more expensive horn tweets on

I'm very interested in your idea Zilla
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Old 13th January 2011, 06:37 PM   #113
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Here's my sketch. I am not able to build complicated cabinets so i always think simple. Basically the sub acts as a shelf for the 'monitor' that is the 12lta + tweeter. This way you can angle the monitor to suit your listening tastes, have the internal volume needed for the sub and the whole thing looks integrated. If you have good wood working skills maybe something more interesting can be done. Feel free to accept, reject or modify.

My speakers are functionally complete. Both dustcaps were removed and i will eventually get around to the 98 cent tweak as well as adding phase plugs. The boxes are sanded but not yet stained. I will post pics tomorrow.

Listened to music until past midnight. The overall presentation is large, dynamic, detailed and simply awesome! If the above tweaks improve things then it will be a bit more awesome. I really enjoy the result.

Zilla
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Old 14th January 2011, 07:01 AM   #114
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Quote:
Originally Posted by db6546 View Post
I guess should have tried kneading the whole whizzer before cutting.

Today I removed the driver and tested it with my WT3. Fs is now 74 Hz and Qts is .54. Based on the size of the box, and that I'll need help on both ends, I'm going to move on from this project.
Yeah, you've got to work them pretty good to damp them all the way.

Gees, that seems like too big an increase based on a 45 Hz Fs, so what was it originally? Now, the B12 needs to be limited to a ~80 Hz XO.

GM
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Old 14th January 2011, 10:09 AM   #115
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I'll need help on both ends, I'm going to move on from this project.
Thats a shame but your ears like what they like and there is no changing it! I wish you acoustical joy in your next project.

I accepted before I bought that any 12" 'fullrange' driver was always going to need help at extremes of the range. The most important thing for me was not crossing over anywhere near the critical 'telephone band'. The 12lta is good from 100-200 thru 8k+ htz

With the ft17h its really good, but once the bass fridge's are complete I'll be doing nothing but smiling
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Old 14th January 2011, 02:18 PM   #116
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Some more pics. Removing dustcap is easy and even makes the driver a bit more interesting to look at. I will fashion a phase plug in the coming days but don't really feel there is anything more to do to the driver since the sound is already very good. Additional tweaks will only make minor differences. It sounds the way it sounds and i enjoy it. The overall sound is big and bold. The last few days i've been enjoying all sorts of live recordings by Fleetwood Mac, Simon and Garfunkel, Bee Gees, Eric Clapton and James Taylor. For fun i've also been listening to Rocky Horror Picture Show and Wicked.

The 12lta may not be perfect but it does things other (smaller) drivers just can't. It gets very loud and remains clear. It's very detailed, dynamic, efficient and bristles with life. It's easy to match with a tweeter and woofer. I enjoyed it even before cutting the dustcap off but it sounds better (less rough and less reverberant) when it's gone. It has an easy, effortless presentation that's forward. It doesn't do pinpoint imaging but after listening to it i have some questions on that topic for future discussion. It really is like a V8 muscle car of the past. And even with their limitations those types of cars are still fun to drive and have their loyal fans.

As i tried larger drivers i continued to like the sound i was getting. I think one can argue that larger radiating surfaces present music with a more lifelike presentation than smaller ones. Don't try larger drivers unless you have the space. I love mine.

This project has me curious about other 12" full rangers... maybe one day i will even try a 15". When the weather gets nicer i will add four rubber feet and finish these off with some nice stain and poly.
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File Type: jpg 12lta-h-frame-1.jpg (52.0 KB, 588 views)
File Type: jpg 12lta-no-dustcap.jpg (80.5 KB, 566 views)

Last edited by Godzilla; 14th January 2011 at 02:34 PM.
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Old 14th January 2011, 03:38 PM   #117
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This driver really wants a small super tweeter stuck on its pole piece or at least suspended over it.

GM
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Old 14th January 2011, 04:00 PM   #118
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I think one can argue that larger radiating surfaces present music with a more lifelike presentation than smaller ones.
Duh! Why do you think I always say 15" is where one wants to start to go 'live'? RCA's Harry Olson worked through it mathematically and experimentally to arrive at this conclusion by the mid '30s and last I checked, the physics of the situation hasn't changed.

Admittedly, there's ways to get a more accurate reproduction over the ultra-wide BW available to us today, but 'on the cheap' WRT to getting vocals 'right' enough, a tweaked 15" 'FR' driver can be convincing for most folks. Unfortunately, I don't know of any inexpensive 'FR' 15" still in production.

GM
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Old 14th January 2011, 04:45 PM   #119
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Forgot to add this: "The single most important attribute of reproduced music is Tone" - Harry Olson
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Old 14th January 2011, 04:58 PM   #120
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>>> Duh!

LOL! But so many enjoy 3" and 4" drivers (including me). Even with all its deficiencies, the 8" Pioneer B20 always had something over those smaller drivers that kept me listening. Even larger, the Beta 12lta excites a room with sound more effectively than any small driver i've come across leaving them sounding... small.

If i wasn't at work i'd be listening to music.
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