How loud a given driver can go is a function of its diameter, its Xmax (physical) and its power handling (thermal) limits. At lower frequencies, it is generally the physical constraint is binding. I am using a subwoofer and want to be able to cross at a relatively low frequency, so the displacement-limited output of the FR unit becomes a critical design element. That is why I asked about 8" drivers. Perhaps I should have made the criterion more explicit, like "100 dB @ 100 hz" - I hadn't thought it through to that level of detail when I posed the question.
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How loud a given driver can go is a function of its diameter, its Xmax (physical) and its power handling (thermal) limits.
Given that there are NO standards for measuring or specifying power handling, not something you can use to directly compare different makes of drivers.
And to mean anything you would also need to factor in the (real) efficiency of the driver
How loud do you intend on playing?
dave
Can you explain how efficiency affects the displacement-limited output? (Are you talking about room gain?) Are you saying that Sd and Xmax specifications are fudged so much that we can't use them to evaluate a driver?
I would like to be able to go to the 102 - 105 dB range.
John
I would like to be able to go to the 102 - 105 dB range.
John
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Can you explain how efficiency affects the displacement-limited output?
John,
It is needed to know how loud things are at the power limit.
ie without the efficiency you are observing a number which is meaningless (AFAIS) in the context of sitting down and listening.
dave
I would like to be able to go to the 102 - 105 dB range.
Peaks of 105 dB are not a problem for a pair of 12p's in vented boxes (Planet_10 MarKenT's). This was at approx. 2.5m listening position, with an 18W/Ch amp, and no signs of distress from either, just my ears.
FWIW, in an 8L closed box, WinISD predicts an SPL of 105dB @100Hz (106dB @ 120Hz) with an input of 25 watts, and a cone excursion of 4.67mm @93Hz. This is with a parametric EQ of 3dB centered @100Hz.
Max. input for the 12p is 30W, with a max. cone excursion of 5.4mm, as per MA.
jeff
If you don't know how loud it is, what meaning does it give you?
The context of this is that my A12.2p play pretty loud (in my large room)
A12.2p not really designed for a sealed box, is what you are really saying is that in a sealed box it doesn't go low enuff?
dave
The displacement-limited output is (can be) calculated in dB SPL - it is an objective measure of loudness.
John
The displacement-limited output is (can be) calculated in dB SPL - it is an objective measure of loudness.
Can you point me to the math?
dave
Peaks of 105 dB are not a problem for a pair of 12p's in vented boxes (Planet_10 MarKenT's). This was at approx. 2.5m listening position, with an 18W/Ch amp, and no signs of distress from either, just my ears.
FWIW, in an 8L closed box, WinISD predicts an SPL of 105dB @100Hz (106dB @ 120Hz) with an input of 25 watts, and a cone excursion of 4.67mm @93Hz. This is with a parametric EQ of 3dB centered @100Hz.
Max. input for the 12p is 30W, with a max. cone excursion of 5.4mm, as per MA.
jeff
Jeff - this is interesting. I have been playing a bit with WinISD but went to a Siegfried Linkwitz spreadsheet for this analysis. I was getting max of 100dB at 100 Hz.
With an efficiency of 92 dB + 25W (14 dBW) = 106 dB, so this seems all okay, assuming the Linkwitz spreadsheet is off. Crap, looks like I might have to go to the formulas and grind it out to see...
John
>>> I am happy with my Tang Band W8-1808.
Me too. Mine are in small sealed boxes. Using an old Infinity sub that has been lying around for years unused. It's a great combo... for now. I love the clear treble the 1808 produces. It's one heck of a tweeter.
Zilla
Me too. Mine are in small sealed boxes. Using an old Infinity sub that has been lying around for years unused. It's a great combo... for now. I love the clear treble the 1808 produces. It's one heck of a tweeter.
Zilla
Attachments
Dave,Can you point me to the math?
dave
This link has the formulae (about 2/3 of the way down):
Closed Box Equations
John
This is good to hear guys - the driver seems a good value.>>> I am happy with my Tang Band W8-1808.
Me too. Mine are in small sealed boxes. Using an old Infinity sub that has been lying around for years unused. It's a great combo... for now. I love the clear treble the 1808 produces. It's one heck of a tweeter.
Zilla
Zilla - what is next? New sub?
John
Do you prefer the midrange on up of the Eminence - tweeter combo to the Tang Band - tweeter combo?The speakers above sounded great until I built these. Eminence 12lta plus tweeter on open baffle above H-frames. They are my reference.
John
>>> What tweeter and woofer are you using ? Looks like a CD with horn and Alpha 15. Passive XO?
It's all very simple actually. It's an Alpha 15 powered by a 100 watt subwoofer amp. I adjust the gain and xover to blend into the main driver. The tweeter is the cheap Eminence with a 1 or 1.5uf cap - I will check the values tomorrow. A cheap Dayton waveguide is used with the compression tweeter.
It's all very simple actually. It's an Alpha 15 powered by a 100 watt subwoofer amp. I adjust the gain and xover to blend into the main driver. The tweeter is the cheap Eminence with a 1 or 1.5uf cap - I will check the values tomorrow. A cheap Dayton waveguide is used with the compression tweeter.
I prefer the Eminence to the TB because it creates a larger sound and a larger sense of scale. The TB is more detailed and transparent but can't do what the Eminence does, IMO. I'm certain others will disagree.
The cool thing about the TB is that it can be used all by itself and produce a full sound from top to bottom. The Eminence cannot. It needs a woofer and tweeter.
The cool thing about the TB is that it can be used all by itself and produce a full sound from top to bottom. The Eminence cannot. It needs a woofer and tweeter.
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