Open Source "Tower XL"

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The 8" Faital 8PR200 has been used with good results with both compression driver on horn tweeters, and dome tweeters with integrated waveguides like the Wavecor TW030WA11(4ohm) TW030WA12(8ohm). A robust dome tweeter like the 1.1" SB Acoustics SB29RDC-4 can support the 1400Hz crossover where beaming starts on a curve-linear cone 8" like the 8PR200.

With and Fs=58Hz and Qts=0.35, a 0.4cuft sealed volume -F3=130Hz with Qtc=0.57 and 92db sensitivity should integrate with the 15" woofers discussed. Baffle step for an 18" wide cabinet starts around 200Hz, where some overlap of the woofer crossover frequency can compensate.
 
The 8" Faital 8PR200 has been used with good results with both compression driver on horn tweeters, and dome tweeters with integrated waveguides like the Wavecor TW030WA11(4ohm) TW030WA12(8ohm). A robust dome tweeter like the 1.1" SB Acoustics SB29RDC-4 can support the 1400Hz crossover where beaming starts on a curve-linear cone 8" like the 8PR200.

These tweeters won't allow to get 92 dB/2.83V/1m with an 8 Ohm impedance rating (as in the spec sheet of the XL Monkey). The Satori TW29BN might work, as it is a bit louder; or th Bliesma T34-A (96 dB/2.83V/1m) or T34-B (Be dome, 97.5 dB/2.83V/1m), which will also go deep (x-over at 1.5 kHz should work fine).
 
Mordikai:
At first look and comparing with the Faital 8PR200, the B&C 8PE21 has more voice coil inductance. You can see it also in more SPL fall off up to 10kHz.

Linesource:
The Faital 8PR200 looks good. I like to simulate the DI of that driver, but they only give the 0 deg and 45 degrees off axis SPL. It should be more accurate for the simulation to have more off axis curves 15 30 45 (60) deg. So, if someone should find measurements, they are welcome…

Mbrennwa:
Wavecor TW030WA12 is on the limit yes, it has 93dB on the plot. But I like the integrated waveguide. Anyway I can calculate its DI to compare with the midrange, just to know.

Edit: sorry, I looked to TW030WA 4 Ohm version, the 8 Ohm is not sensitive enough, you are right Matthias
 
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A robust dome tweeter like the 1.1" SB Acoustics SB29RDC-4 can support the 1400Hz crossover

I wouldn't use the SB29RDC crossed that low even though from the freq. response and fs perspective it can handle it. The reason I wouldn't is that it has a massive spike in higher order harmonic distortion around 1.1kHz that may lead to a very fatiguing sound. See the distortion measurements at the bottom of this page.
 
Zmin ~ 6ohms, SPL ~90 db

Attached quick sims using just datasheet plots of the 8" Faital 8PR200 with the SB29RDC_4 dome tweeter, and with the Wavecor TW30WA12-8 waveguide dome to provide average SPL and Impedance for discussion.

Wavecor TW30WA12-8 waveguide dome seems worth further consideration.


The expensive Satori 1.1" TW29RN-4 NdFeB magnet tweeter has 96db sensitivity and good reviews for tube friendly speakers. A possible partner for the 8" B&C 8PE21 midrange....which has an -F3~300Hz in a small sealed volume. The 8PE21 T/S parameters look designed for front horn loading.
 

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  • Faital Wavecor8.JPG
    Faital Wavecor8.JPG
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  • Faital SB29RDC.JPG
    Faital SB29RDC.JPG
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Attached quick sims using just datasheet plots ... the Wavecor TW30WA12-8 waveguide dome to provide average SPL and Impedance for discussion.

Hmmm. The Wavecor TW030WA12 datasheet indicates SPL below 90 dB at frequencies <4 kHz. I don't see how it would be possible to get higher SPL. Was there a mixup with the TW030WA11 data in the same file?
 
What do you think of these two cabinet and driver concepts?

The same front baffle dimensions, 112 cm high and 47 cm wide. One cabinet is 60 cm deep for 250 L bruto volume and the other 50 cm deep for a 205 L bruto volume. 19 mm for the walls, except the front 30 mm.
Subtracting 20 L for the internal midrange cabinet, 5 L for the drivers and 5 L for the bracing, and a part for the port volume, this will result in one cabinet with 225 L netto and the other 180 L netto for the woofer.

Concept 1

- Cabinet W x H x D = 47 x 112 x 60 cm
- Woofer AE TD 15X
- Midrange AE TD 8M
- Tweeter tbd
- Port can be adjusted for B4 or extended BR

Concept 2

- Cabinet W x H x D = 47 x 112 x 50 cm
- Woofer Faital 15FH500 or 15FH520
- Midrange Faital 8PR200
- Tweeter tbd
- Port can be adjusted for B4 or extended BR

Some remarks:
- Woofer for concept 2, in my simulations I see that the 15FH520 is more suitable to cover both B4 and extended BR. Has to be confirmed.
- Midrange for concept 2, Faital 8PR200 is a first proposal.

If there is enough consensus about this proposal , I can draw more detailed drawings to discuss further and to make cabinet models for the simulation later on.
 
Hi Paul,

I am designing a very similar concept quite now and I have to agree, the 15FH520 is on top of my list. Even before the BMS 15N630. The BMS plays a few Hertz lower, but the Faital needs less volume. Group-Delay wins the Faital too. Everything else looks very identical.
Sensitivity for both is 95dB in calculation, we have to subtract some dB's sure.
 
Morel ET 448 - 8Ohm - 92db - Fs 750Hz.

Looking at the SPL chart in the datasheet this looks more like 90 dB. Also, the SPL is up there only at >3 kHz.

Morel CAT 378 - 8Ohm - 93db - Fs 700Hz.

This might be loud enough, but again the SPL response looks like it will not work out below 2.5 or 3 kHz.

Just from looking at the SPL response curves, I believe both tweeters will need an x-over at 2.5 kHz or maybe better at 3 kHz. That will not be easy to achieve with an 8" midrange.

What's the anticipated x-over frequency?
 
The Morel CAT 378 looks interesting. Out of the off axis responses I have calculated the DI and compared with the DI of the AE TD8M. Morel in blue, TD8M in green.
Measurements of the Morel below 2kHz are very poor with much ripple, we have to look to mean values.
DI AETD8M and Morel Cat378.JPG

The DI is about the same around 2 KHz. A crossing at 1800 Hz can be ok to make DI flat, if the tweeter excursion becomes not too high, we have to look at it later.

These are DI results on infinite baffle. Placing the drivers in the cabinet will change the DI.
Above 2 kHz there will appear probably some ripple on the tweeter DI because of diffraction, but the mean value should stay the same.
Below 1 kHz the DI will increase due to the bafflestep. It will be almost the same increase for both drivers.
The total combined DI will not be flat anymore with an expected DI dip around 1 – 2 kHz. That cannot be solved by a tweeter waveguide, only by making the bafflestep behavior more smooth, for example by making a slow curved baffle in horizontal direction. That isn’t the intention for this project.
The DI with drivers in the cabinet can be made more flat maybe, by choosing a higher crossing, around 2.2 kHz.

These are only some expectations based on preliminary off axis curves. The final cabinet measurements will give a better view on this.

Measuring the drivers before on IEC baffle would be very informative also, like mentioned already before.
 
Concept 1
- Midrange AE TD 8M
- Tweeter tbd

Concept 2
- Midrange Faital 8PR200
- Tweeter tbd

The DI is about the same around 2 KHz. A crossing at 1800 Hz can be ok to make DI flat, if the tweeter excursion becomes not too high, we have to look at it later.

A few thoughts (I may have missed a few arguments before this post, so please excuse me if I seem ignorant):

  • 8" is rather large for a midrange that needs to work with a tweeter crossed over at around 2 kHz. Most 8" drivers I am familar with are not very clean above 1 kHz or so (resonances in spider or surround, cone breakup, etc.). Remember that LEAP (or other simulation tools) cannot know about such imperfections, and so the simulation results will never show such real-world issues. I have a gut feeling that using a smaller midrange to go up to 2 kHz or so would be better in my opinion.
  • Finding a tweeter that will match the requirements for the x-over frequency (1.8 to 2 kHz), dispersion (determined by the midrange), SPL (>92 dB), impedance ("8 Ohm"), etc. may not be trivial. This might be easier with a smaller midrange driver.
  • The Faital 8PR200 datasheet shows a few wiggles in the impedance curve at about 500 Hz. Is this a resonance in the spider/surround assembly? The SPL curve tends to show a bump centered at this frequency. How clean is the Faital response?
  • I could not find a datasheet for the AE TD8M, no impedance curve, and the only SPL curve I found has very strong smoothing applied (so resonance/breakup issues are hard to see). Maybe I am just blind, but I am a bit surprised that a company with a "high quality" aspiration like AE does not seem to publish any meaningful datasheets. Designing with the AE TD8M without meaningful impedance and SPL data seems like shooting in the dark.
 
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