12" woofer for SEOS12 build, 12PLB100?

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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
 
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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!

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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 ;

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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 ;

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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
 
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.
 
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
 
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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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
 
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
 
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I was able to run some quick response tests on the DE500 last night. Plots are about 5-10 degrees off axis at about 1.5 m. They looks fairly similar to the data EarlK posted (from Autotech?) earlier in this thread.
Dan
 

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Hi Dan,

Thanks for the new graphs ( they're pretty interesting in their general agreement with other peoples measurements, including those Autotech graphs that I posted previously ).

A few thoughts ( no specific order of importance );

(i) To give the de500 the best audition ( or chance in a comparison to the de250 ), consider implementing some version of a 30 PPI Geddes filter // before deciding on the driver's sonics merits for your use .

(ii) Are you able to create .ZMA impedance files of your drivers for network design purposes ?

(iii) Do you have some proficiency in working with XSim ?

(iv) Passive filters do have a subtle difference in sound when compared to active ( generally, they are less dynamic due to resistive losses ) > though this attribute benefits the speaker designer when he/she is wanting to match-up components that have such large disparate sensitivities .

IOW, I believe it'll be to your benefit if you wire up some horn padding networks ( that also include some basic HF compensation ) .
- You can still do everything else electronically ( for now ) when it comes to creating HP's & LP's ( as well as any needed notch-filters ) .

(v) I've already created passive filters for these drivers using for your response pics ( as well as AutoTechs pics ) .
- I'll post them here at some point.

:)
 
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Hi Dan,

Thanks for the new graphs ( they're pretty interesting in their general agreement with other peoples measurements, including those Autotech graphs that I posted previously ).
Hi Earl,
No problem. I too found it interesting how close they were to the Autotech measurements. I noticed their data was taken at 1m, mine was 1.5. When I have a bit more time, I will lug everything upstairs to get better 2m measurements and full polar data. The 7 1/2' ceilings in my basement limit the reflection free window unfortunately.

A few thoughts ( no specific order of importance );

(i) To give the de500 the best audition ( or chance in a comparison to the de250 ), consider implementing some version of a 30 PPI Geddes filter // before deciding on the driver's sonics merits for your use .
This is on the agenda. I'm not sure I'll have the time to fab up some foam plugs before I have to send either the DE500's or the DE250's back. I will say that so far the DE250's sound so good I wouldn't feel a need for the foam plugs, but I'd still like to try it.

(ii) Are you able to create .ZMA impedance files of your drivers for network design purposes ?

(iii) Do you have some proficiency in working with XSim ?
I haven't worked in XSim. I take my measurements with HOLM Impulse and SoundEasy. SoundEasy can take impedance measurements but I'm not sure if I can export a zma file from it. It might take me some time to get set up for impedance measurements. I'll be sure to post them when I get something.

(iv) Passive filters do have a subtle difference in sound when compared to active ( generally, they are less dynamic due to resistive losses ) > though this attribute benefits the speaker designer when he/she is wanting to match-up components that have such large disparate sensitivities .

IOW, I believe it'll be to your benefit if you wire up some horn padding networks ( that also include some basic HF compensation ) .
- You can still do everything else electronically ( for now ) when it comes to creating HP's & LP's ( as well as any needed notch-filters ) .
This sounds like a good idea. For now, the output of my audio interface runs to a couple different amps. I dialed down the volume control on the amp feeding the compression drivers so I wouldn't need to scale the tweeter signal down digitally. My current filtering software is Frequency Allocator from Thuneau. It works very well and uses regular minimum phase filters and eq so reproducing what it does with passive circuits is not that difficult. I usually take a couple response measurement with and without filtering. Then in SoundEasy a circuit can be made to get the noneq'd response to match the filtered measurement. The final result seems fairly close subjectively. The main improvement I've noticed when running the passive circuit is the lack of noise from not having to run my old Yamaha receiver to provide the extra channels of amplification. :whazzat:

(v) I've already created passive filters for these drivers using for your response pics ( as well as AutoTechs pics ) .
- I'll post them here at some point.

:)
Thanks Earl!

Dan
 
Earl,
You had suggested the Deltalite's above. Those sound like a good option and quite a bit cheaper for me than the B&C's. Do you know what the limiting factor on sensitivity for the DE250/SEOS12 combination is? I realize you lose about 9-10 dB performing the CD equalization back to flat. It sounds like maybe another dB or few if 30 ppi foam plugs are added. How sensitive of a woofer can I expect to mate well to the final compression driver/waveguide combo?
Dan
 
Earl,
You had suggested the Deltalite's above. Those sound like a good option and quite a bit cheaper for me than the B&C's. Do you know what the limiting factor on sensitivity for the DE250/SEOS12 combination is? I realize you lose about 9-10 dB performing the CD equalization back to flat. It sounds like maybe another dB or few if 30 ppi foam plugs are added. How sensitive of a woofer can I expect to mate well to the final compression driver/waveguide combo?
Dan

Hi Dan,

From my perspective, the woofers sensitivity will limit your project to around 95db ( for a "real" 8 ohm woofer ) .

:)
 
Hi Dan,

From my perspective, the woofers sensitivity will limit your project to around 95db ( for a "real" 8 ohm woofer ) .

:)

okay, that's good to know. So the compression driver won't be the limiting factor in that case. I had noticed the Deltalite's rated sensitivity of 99.9 dB and was wondering. Looking at it's response plot, it doesn't get to 100 dB until above 1000 Hz. I'll be crossing over somewhere in that range so it looks like the woofer would be the limiting factor as you suggest.
Dan
 
Earl,
Do you know what the DE250/SEOS combo sensitivity will be at after equalization? How much padding is still needed to get down to 95 dB?
Dan

Hi Dan,

Here's an HF Comp. network for you ( if you want to try one ) ;

> CLICK the PIC ( it's quite oversized )!!

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The LCR notch filter isn't mandatory ( though it'll help for comparative purposes I believe ) .

:)

BTW, the FRD files are traces of your own FR captures, while the ZMA files were created from the AutoTech pic .
 

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