I recently purchased a single celestion FTR15-4080HDX for a song. I realize it is probably not the best driver for a sub, but my intent is modest.
One other reason for purchasing this model celestion is that I intend to build an enclosure which will double as either a small table or bench (the idea of filling a room with numerous pieces of furniture does not appeal to me). Internal dimensions of the enclosure must not exceed 33 W x 19 H x 13 D (inches), or its equivalent volume. (The tuning freq shall be 40 Hz. I prefer a single, dual-flared port.)
I may consider purchasing one more driver for use in the same build (i.e., incorporating two drivers as oppose to one), for an enclosure not exceeding the above noted volume [if deemed possible]).
I have queried the internet to exhaustion for a design using this driver, to no avail. I also played with an app on my tablet, but, considering I have never construted a sub, I am skeptical as to the efficacy of such an app.
Perhaps the minds at diyAudio can enlighten me, seeing that to some, calculations for such an endeavor are comfortably shot from the hip.
I purchased an FFT app for my tablet, which though crude, may provide an adequate measurement of the completed sub. Or not.
One other reason for purchasing this model celestion is that I intend to build an enclosure which will double as either a small table or bench (the idea of filling a room with numerous pieces of furniture does not appeal to me). Internal dimensions of the enclosure must not exceed 33 W x 19 H x 13 D (inches), or its equivalent volume. (The tuning freq shall be 40 Hz. I prefer a single, dual-flared port.)
I may consider purchasing one more driver for use in the same build (i.e., incorporating two drivers as oppose to one), for an enclosure not exceeding the above noted volume [if deemed possible]).
I have queried the internet to exhaustion for a design using this driver, to no avail. I also played with an app on my tablet, but, considering I have never construted a sub, I am skeptical as to the efficacy of such an app.
Perhaps the minds at diyAudio can enlighten me, seeing that to some, calculations for such an endeavor are comfortably shot from the hip.
I purchased an FFT app for my tablet, which though crude, may provide an adequate measurement of the completed sub. Or not.
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Celestion FTR15-4080HDX
As a test project you can do a reflex 90Liter (net) tuned to 35Hz but expect -10dB@30Hz.
Dimensions for the 2 ports (each) are: Length 28.92cm = 11 25⁄64in, Diameter 9.4cm = 3 45⁄64in (internal). Volume for double ports tubes is about 4.25Liters plus 4L for the 15" driver.
As a test project you can do a reflex 90Liter (net) tuned to 35Hz but expect -10dB@30Hz.
Dimensions for the 2 ports (each) are: Length 28.92cm = 11 25⁄64in, Diameter 9.4cm = 3 45⁄64in (internal). Volume for double ports tubes is about 4.25Liters plus 4L for the 15" driver.
I will compare your suggestion with the app on my craptablet, though from what I recall, the measurements should be quite similar. Thank you.
Hi,
Its a PA driver suited to going very loud with lots
of power as a PA bass unit. It could be used in
a vented box of about Vas (105L) but won't
go very deep. It could be used in a sealed
box of about 50L and EQ'd for decent bass.
rgds, sreten.
Its a PA driver suited to going very loud with lots
of power as a PA bass unit. It could be used in
a vented box of about Vas (105L) but won't
go very deep. It could be used in a sealed
box of about 50L and EQ'd for decent bass.
rgds, sreten.
After reviewing the calculations generated by the android app, 90L appears to be optimum (the volume quoted by 'Inductor'. The sealed is as you stated, (approximately 50L), though sealed shows a roll-off earlier than I would desire. If passive radiators were inexpensive, I would attempt such a design, but the ones I found suitable cost more than the driver.
90L vented for this driver it shall be.
Thank you.
I thought about attempting a TH, especially given that the target frequency is indeed 40 Hz, but from the information I have absorbed, the driver may be deficient in some aspects for that application. Additionally, I decided long ago that if I ever build a TH (something I would only attempt after pedantic peer review followed by near paranoid attention to detail in workmanship), it will be modeled for half space. I doubt such a horn would be at or less than a meter long, even when folded three times. (I could be wrong, however. I have not reviewed those notes in some time.)
Hi,
Easy enough. The vented power handlng will drop like
a stone below the relatively high tuning frequency,
whilst a simply EQ'd (first order) sealed has no
similar bottom limit, it will go much lower in room.
The EQ of sealed gives you room integration adjustment.
Fact is the 40Hz Fs driver won't go low without EQ.
It has enough Xmax to go low at decent levels,
or indecently loud with no real low bass vented, but
this needs an active high pass filter to be a reality.
rgds, sreten.
Although all of my notes are solely academic (sans the few pairs of loudspeakers I constructed long ago), I agree with sreten--the bass extension/rolloff provided by a sealed design is preferable to the drop in response a bass reflex design offers for a driver covering the same span. That said, other factors aside from a preference in response may determine the selection of the enclosure (many drivers are optimum for sealed or ported, but often not both).
For example, the celestion driver I am for which I await receipt should provide acceptable response from 40Hz to 120Hz, but NOT any frequency below, 40Hz. I am forced to sacrifice 20Hz to 40Hz due to the driver (a sacrifice I am comfortable with, since I found the driver on a substantial discount and my intention is modest). I could attempt to FORCE the driver to operate to 40Hz in a sealed enclosure, but that would probably not render desirable results.
I prefer to yield to logic.
Of course, should I buy or build my own home in the future (planning to), then I will purchase faital PRO 18s I elected for a half-space TH (for which those drivers appear perfect). (I'm thinking one to the front and one to the rear of the listening area, built into the walls or ceiling). (An online retailer denied me the purchase of one recently, stating that the driver I ordered [which was in stock at the time of order], magically disappeared during the transaction. In actuality, it is likely that the retailer noticed there was a substantial decrease in price and decided not to honor the credit card sale--the approximately 500US driver had been discounted to 89US. Bastard. But that is off-topic.)
Now, I would be delighted to receive the delivery this weekend.
Unless, of course, this driver (albeit ordered from a different vendor), is also mysteriously transported to the 'out-of-stock' realm.
Unless, of course, this driver (albeit ordered from a different vendor), is also mysteriously transported to the 'out-of-stock' realm.
Some quick modelling suggests that you could get a 40 Hz TH with this driver that has a sensitivity of 100dB/2.83V/1M in its passband. Net volume will be between 220~260 litres depending on what response shape you're happy to accept. The compression remains quite low too, above 1/3. A suitable fold would be something like the "Single Sheet" 15 described in another thread.
Hi,
No. It will do 20Hz to 40Hz as well as any other 15"
with the same excursion sealed stuffed and EQ'd.
rgds, sreten.
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