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Multi-Way Conventional loudspeakers with crossovers

12" woofer for SEOS12 build, 12PLB100?
12" woofer for SEOS12 build, 12PLB100?
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Old 9th August 2017, 05:33 PM   #1
Dan_E10 is offline Dan_E10  United States
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Default 12" woofer for SEOS12 build?

I'm starting a build based around the SEOS12 waveguides. I'm looking for a 12" woofer to use in a sealed cabinet. These will be used full range with a multi-sub setup so I don't need deep bass extension. The AE TD12M is a possibility but would be stretching my budget. The B&C 12TBX100 as used in Geddes' Abbeys looks like a good option for a bit less money than the TD12M's. While looking through B&C's 12" woofer lineup, I came across the 12PLB100. I haven't seen too much discussion of this woofer. The specs listed on B&C's website for it show it to be a couple of db more sensitive than the TBX100, 97 vs 95. If the Thiel-small parameters are accurate it looks like it might work as well or even better in a sealed box than the TBX100. The FR response shown looks a bit flatter than the TBX as well. It's not clear to me if and what the motor differences might be. Both list aluminum demodulation rings, but on Parts Express it claims dual demodulation rings for the TBX. Anyone have any experience or thoughts on the 12PLB100's?

FWIW, I've got a pair of B&C DE250's and DE500's arriving soon for the waveguides. I know that compression driver sensitivity on the high end drops quite a bit on a CD waveguide. If the 97 db figure for the PLB is accurate, would that potentially be too high to mate with either of these compression drivers once they are eq'd back to flat response? I'm interested to try out foam plugs ala Geddes in the waveguides as well so it seems I might lose a db or two of sensitivity from the compression drivers for that.
Dan

Last edited by Dan_E10; 11th August 2017 at 08:39 PM.
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Old 10th August 2017, 12:32 PM   #2
EarlK is offline EarlK  Canada
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Hi,

Unless you love the challenge of designing effective crossovers, I think you'd be far far ahead if you simply bought ( from DIYSG ) a proven design such as the HT-12 .

It uses ( for the woofer ) an Eminence DeltaLite II 2512 ( 12" ) to great effect .

The Eminence DeltaLite II 2512 is a 12" I was going to recommend first ( since it's Ts parameters show it to be a very reasonable stand-in for an Altec 414 ). It has garnered some great reviews over at AVS forum by DIYSG users.

The Altec 414-8C was another ( Legacy ) choice I was going to suggest ( & quite conveniently, "Dearly Departed Zilch" had years back worked up a design using the 414-8B here!

Click the image to open in full size.

Back to the Emmi 2512, ( also some years back ) Bill Waslo worked up this network using the 2512 & the horn/driver combo ( which you currently have on hand ) .
- I'm pretty sure this rare schematic disappeared when the DIYSG forum migrated to it's present form .

- Here's the necessary network schematic ;

12" woofer for SEOS12 build, 12PLB100?-a988fd3b_2_10_04_12_7_11_09-png


The B&C 12PLB100 ( spec wise ) looks to be BC's answer to the JBL 2206H ( while their TBX variant sports a massive motor driving a much heavier cone ).

- Personally ( since I use a lot of JBL components and know their QC ) I would just buy a pair of used 2206's if I wanted a weighty cone that could be hammered on ( so-to-speak ) .


PS; the de250 looks to be the easier of the two to design for the SEOS 12. See this ;

12" woofer for SEOS12 build, 12PLB100?-de250_de500_seos-12-png
Attached Images
File Type: png a988fd3b_2_10_04_12_7_11_09.png (44.8 KB, 769 views)
File Type: png DE250_DE500_SEOS-12-P.png (184.8 KB, 748 views)

Last edited by EarlK; 10th August 2017 at 01:00 PM.
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Old 10th August 2017, 06:39 PM   #3
Dan_E10 is offline Dan_E10  United States
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Thanks for the input Earl. I came across SEOS designs with the 2512 in other threads here or at AVS forum. I hadn't really considered Altecs up to now, I'll look into those in more depth.

Designing a crossover won't be an issue for me. I will start out active using Frequency Allocator, and then build a passive XO at some point if I like the results well enough. Certainly I'll consider Bill's designs as starting or end points if I end up using one of the same woofers.
Dan
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Old 11th August 2017, 04:28 AM   #4
LineSource is offline LineSource  United States
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The Faital 12PR300 in a 1cuft sealed cabinet is often used with the SEOS-12, SEOS-15, and PRV-WG35 waveguides crossed ~1.3kHz.
-Study how the modest Le=0.4mH maintains a constant low impedance well past the 1-2kHz crossover region.
-Low Le midbass can carry up into the tweeter unless a steeper(BW3, LR4) electrical crossover circuit is used.
-A 1cuft sealed box has -F3~100Hz, which supports good baffle step integration with an ADJACENT woofer(Mms < 200g, avoid subwoofer Mms >300g).
-Studies prove that a woofer's position in a room can be located with crossovers over 80Hz.

Please share you crossover work on the DE500.
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Old 11th August 2017, 03:03 PM   #5
Dan_E10 is offline Dan_E10  United States
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Quote:
Originally Posted by LineSource View Post
The Faital 12PR300 in a 1cuft sealed cabinet is often used with the SEOS-12, SEOS-15, and PRV-WG35 waveguides crossed ~1.3kHz.
-Study how the modest Le=0.4mH maintains a constant low impedance well past the 1-2kHz crossover region.
-Low Le midbass can carry up into the tweeter unless a steeper(BW3, LR4) electrical crossover circuit is used.
-A 1cuft sealed box has -F3~100Hz, which supports good baffle step integration with an ADJACENT woofer(Mms < 200g, avoid subwoofer Mms >300g).
-Studies prove that a woofer's position in a room can be located with crossovers over 80Hz.

Please share you crossover work on the DE500.
Hi LineSource,
I hadn't considered the 12PR300 before. I see some discussions on it and measurements at driver vault. Do you know if the published TS parameters and the sensitivity of 99 dB are accurate?

On subwoofer crossover points, I don't lowpass the satellites. They run full range and the previous speakers I've used with the sub array have been sealed as well with ~100 Hz roll off. I would be interested in a lower rolloff on the midbasses to allow more overlap between the subs and satellites. I haven't had issues with localizing subs in my setup though.

The first time I heard a multi sub array was at Earl Geddes' house when I listened to the Summa's. The quality of the bass stood out to me.

I will share whatever I come up with for the DE500 if I end up choosing it. I will be able run some measurements and crude listening tests by mounting the SEOS's on top of my existing speakers and setting up a crossover in Frequency Allocator. I will have to make a decision before my 45 day window is up at Parts Express to return either the DE250's or the DE500's. It's not optimum, but hopefully I can get an idea of whether one or the other stands out or if they're basically interchangeable. A passive crossover wouldn't come until I have cabinets completed and an active crossover I'm happy with.

Dan
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Old 11th August 2017, 10:50 PM   #6
Dan_E10 is offline Dan_E10  United States
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Time for the fun to begin!
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Old 12th August 2017, 10:04 PM   #7
LineSource is offline LineSource  United States
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Have you compared maintaining stereo woofers in your room, like a front/back quartal configuration, versus summed mono woofers?

1) Stereo bass down to 20Hz has been produced in low distortion, high SPL since 1982 on CDs, DVD-As, SACDs, and 5.1 movies.
2) Most people with normal hearing can identify the difference between stereo vs. mono bass. Stereo bass has phase for location.
3) At frequencies below 80Hz most people with normal hearing cannot isolate the physical location of the woofer.
------Expert listeners can isolate location of woofers down to 60Hz by focusing on impact harmonics, port noise, upper harmonic distortion.
4) Not being able to locate the subwoofer is a good cost simplification, but summing low bass into mono degrades true stereo recordings.
5) With stereo subwoofers, any out-of-phase bass information in a true stereo (acoustic) recording is reproduced properly at full level, adding immensely to the perceived width and depth of the room in which the recording was made.
6) Irregular room shapes and furniture can have a large effect on even subwoofer frequency soundstage.
7) Geddes: “The mains should be designed for the best possible direct field with as flat a power response as possible. Equalization of the mains could only make them worse.”
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Old 13th August 2017, 02:36 AM   #8
Dan_E10 is offline Dan_E10  United States
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Hi LineSource,
To be honest, it's been a while since I had the subs connected. Since I've been doing a lot of swapping in and out drivers and running active crossovers to prototype things, it's a little tough to take the time to connect the subs.

My original use of the subs were in stereo. The first two were bass modules from BESL who used to sell speaker kits. The bass modules were made to be stands for their sealed monitors. and I used them in that way. It wasn't until reading through the multi sub thread here and then subsequently hearing Geddes' multisub array that I bought a third sub to try it out. It's actually a bit of a pain to sum to mono for all three subs since I run them off of speaker level connections. For a while I think I ran the first two as stereo and ran the left and the right channels into the third to run it as mono. You've piqued my curiosity and I think I try experimenting with stereo subs again. I haven't tried the other arrays mentioned by Welti.

Dan
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Old 13th August 2017, 02:43 AM   #9
Dan_E10 is offline Dan_E10  United States
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First listening tests with the DE250/SEOS12 sitting atop some other speakers I had on hand with a Silverflute 8" woofer were quite a success. Crossing over at 1000 Hz LR4 sounded very good, exceptional really considering how crude the setup was. They were run without a baffle, I imagine there's quite a bit of mouth diffraction that could be eliminated when the SEOS is mounted on a baffle with roundovers of an appropriate radius. Despite this quick and dirty setup, the speakers imaged very well and disappeared effectively. It was very easy to dial in a pleasing tonal balance. The DE250's seem very malleable. The quality of the treble was actually not too different from the Scan Speak 9500 domes I've been used to but with much more dynamics. That was really a pleasant surprise. With the 9500's, they will play loud but they reach a point were I want to turn the volume down since they sound a bit less pleasant. None of that was necessary with the DE250's. I haven't tried out the DE500's yet, hopefully in the next couple of days.
Dan

Last edited by Dan_E10; 13th August 2017 at 02:47 AM.
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Old 13th August 2017, 07:04 PM   #10
Dan_E10 is offline Dan_E10  United States
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Even like this they can sound quite good. This is before the equalization for CD.
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File Type: jpg DE250_HOLM.JPG (133.5 KB, 118 views)
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