Looking for recomendations on 15" woofers

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Inductor

Inductor

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Joined 2006
badman

badman

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Joined 2003
pothaudio.com
ScottG said:
Beat me to it.. :D
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I think you both may be overestimating the effect- the onset of beaming isn't a brickwall, it's a mild transfer function, and won't be as big an effect overall as you seem to be predicting. Consider that CD 2 ways all have a lobe, and so if the woofer is suppressed off-axis, the waveguide output will play more of a role and counteract the beaming somewhat.
 
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DougL

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Joined 2004
It seems the SEOS 15 has a recommended lowest crossover frequency of 850Hz so that might be ok. Haven't seen any plots though, it's just the manufacturer/dealers recommendation.

It has a 1" throat though and there are not many 1" drivers which can go that low.
I think BMS has a couple that get close
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Extrapolating from the SEOS 12, it should be close. The Suma has the B&C DE250 crossed over at about 800 Hz.
So that should not be a show stopper. I agree that If I am crossing low, I have a very limited choice of drivers.
 
Helmuth

Helmuth

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Joined 2008
DougL said:
Extrapolating from the SEOS 12, it should be close. The Suma has the B&C DE250 crossed over at about 800 Hz.
So that should not be a show stopper. I agree that If I am crossing low, I have a very limited choice of drivers.
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For hifi it isn't a problem to cross low because the voice coil only sees a few watts. You have to look at thd at XO though this can become a problem.

I did try a DE25 sounded good like the beyma cp385Nd the titanium dome sounds a bit brighter.
http://profesional.beyma.com/ingles/pdf/CP385Nd.pdf.

18sound has great qaulity drivers to.
this is nice smooth.
http://www.eighteensound.com/index.aspx?mainMenu=view_product_simple&pid=266
An externally hosted image should be here but it was not working when we last tested it.
 
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ScottG

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Joined 2003
badman said:
I think you both may be overestimating the effect- the onset of beaming isn't a brickwall, it's a mild transfer function, and won't be as big an effect overall as you seem to be predicting. Consider that CD 2 ways all have a lobe, and so if the woofer is suppressed off-axis, the waveguide output will play more of a role and counteract the beaming somewhat.
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I've shown the effect in the rather good design that was posted to.

Overestimating, not really - more caution with an alternative approach.

It really depends on the crossover, the horn and it's dispersion pattern at the bottom of its range, and the pressure loss from the 15" above its low-pass. For someone that has done this sort of crossover work a lot - it won't be difficult, BUT for someone that hasn't it might take awhile.
 
Helmuth

Helmuth

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Joined 2008
tinitus said:
that have been my thought too, but I'm less sure about it now
it does have its low ressonance point for a reason, I suppose
sorry if it's too much 'layman terms' :D
but it is ressonating because it does not like that frequency very much, right ?
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Resonance is the result of less air-load due the sum of suspension, area Sd plus xmax that is at its low-frequent limit and you put in signal with that frequency.

It is like a swing that every time gets a new push. And the air resistance of that swing isn't high enough to loose the energy to the air. So the impedance gets a peak there.

In fackt a driver will resonate on the resonance frequency it likes that because it loses stored energy the slowest at resonance frequency.
 
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ScottG

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Joined 2003
Oh, I should also note that the size of the baffle in relation to diffraction peaking with a more "omni" nature makes a difference on the lower end of the crossover.

Basically in a 15" woofer to wide dispersion horn, assuming a low crossover point (less than 1 kHz) where the horn has lost most pattern control, it's best to have a small baffle for the woofer to match the wide dispersion of the Horn's output.

For other reasons it's also a good idea to separate the horn from the driver baffle as well (i.e. 2 part enclosure of Horn + Woofer with about 2-3 inches of separation provided the crossover is low enough).

If you need more volume for the woofer you can always do a double box with multi-pipe connection while still retaining the same diffraction profile of a smaller box.
 
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John_E_Janowitz

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Joined 2004
aespeakers.com
Generic George said:
By all accounts the TD-15M is an top class woofer, but you would probably need to be prepared to wait at LEAST 6mo to a year or more for them. If you do want some, your best bet is to try and find someone from the group buy he did last year who's plans changed or decided on different woofers due to the wait involved.
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While I realize you are referring to the delays with the group buy woofers, please realize that regular orders coming in have not experienced delays like this and will not in the future. Over the past few months many things have had to happen within the shop that I will detail shortly on my forum. Throughout all of the changes and construction, nearly all production of woofers has been caught up nicely as well. The oldest woofers on the regular build list that haven't been made yet were ordered on Jan 22. Things are well back within the 2-4 week lead times on any new orders.

Out of the 250 woofers ordered in the group buy, about 40 are remaining to be completed. There will be 20 of those finished by early next week at the latest. I expect the remaining 20 to be scheduled in within the following 2 weeks around some OEM builds.

In addition I have a few TD15M-8ohm stocked that were built extra during the group buy builds. Those are able to be shipped immediately. I also plan to stock whichever TD12 is going to be most common for use with the SEOS12 waveguide.
 
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ScottG

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Joined 2003
murphythecat8 said:
beyma drivers are good, but never seem to be mention around here
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..but with a budget of around $100 per driver they are out as well.

In fact you can pretty much stick to a Parts Express search for 15" pro drivers with a "low/high" search parameter and get most of the driver's available in this price range. MCM Electronics has a few others on offer as well. Other than that there isn't much left to choose from. :eek:

From there I guess it's a matter of linearity, T/S param's for the design, and getting a lower Le at 1 kHz if possible. Unfortunately few manufacturers provide polars (..Selenium is an exception).

Inductor's suggestion of the Celestion TF1525 is probably as good as it gets all-round, but the Selenium 15PW3-SLF isn't bad either.
 
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