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What drivers to load in empty JBL SR4731X boxes
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jacktheripper View Drop Down
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Points: 13 		Post Options Post Options   Thanks (0) Thanks(0)   Quote jacktheripper Quote  Post ReplyReply Direct Link To This Post Posted: 01 November 2017 at 4:53pm
I've only heard Faital Pro in the Nexo PS15mkII cabs and they sound really muddy and awful.
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_djk_ View Drop Down
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"My only question is which would be the better sounding and/or louder compression driver the JBL 2447 or the BMS 4555?"

The 4" diaphragm on the JBL will allow for more output with less distortion than the 1.75" diaphragm on the BMS in the lower octaves.

The Faital looks like a reasonable driver, although it only has a 3" coil, vs the 4" on the 2206. The efficiency Eta Zero) is the same, 2.6% vs 2.5%, the Faital may play a fraction of a dB louder as it is 5.1Ω vs the JBL being 5.3Ω

Don't waste your money on an aftermarket JBL diaphragm, I've never seen one the holds up or sounds as good as an original.

http://www.cheapjackaudio.com/product-page/jbl-d8r2450-diaphragm

The 2450SL version sounds cleaner, the original 2450 sounds brighter

http://reconingspeakers.com/product/jbl-d8r2450sl-diaphragm/
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jacktheripper View Drop Down
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Points: 13 		Post Options Post Options   Thanks (0) Thanks(0)   Quote jacktheripper Quote  Post ReplyReply Direct Link To This Post Posted: 02 November 2017 at 10:08am
Thanks for that, what about the Beyma driver here I mentioned it has a sensitivity of 100db and a 4" voice coil, the thiele small parameters aren't spot on but they're close.
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gen0me View Drop Down
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Points: 999 		Post Options Post Options   Thanks (0) Thanks(0)   Quote gen0me Quote  Post ReplyReply Direct Link To This Post Posted: 02 November 2017 at 10:35am
It has totally different qes. Faithal is ~pretty close.
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Elliot Thompson View Drop Down
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Points: 5175 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Elliot Thompson Quote  Post ReplyReply Direct Link To This Post Posted: 02 November 2017 at 10:38am
Originally posted by jacktheripper jacktheripper wrote:

Thanks for that, what about the Beyma driver here I mentioned it has a sensitivity of 100db and a 4" voice coil, the thiele small parameters aren't spot on but they're close.



Stay with the Faital Pro. The Beyma you are considering is aimed for horn-loaded boxes. High Sensitivity drivers always equate to less Bass.

Best Regards,
Elliot Thompson
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jacktheripper View Drop Down
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Points: 13 		Post Options Post Options   Thanks (0) Thanks(0)   Quote jacktheripper Quote  Post ReplyReply Direct Link To This Post Posted: 02 November 2017 at 11:11am
But I don't care about bass with the SR4731x cabs i'll always be using them with four double 18" subs and the Faital Pro has only a 3" voice coil and as far as i'm aware the voice coile size effects power compression doesn't it? The bigger the voice coil size the lower the power compression generally.



Edited by jacktheripper - 02 November 2017 at 11:15am
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MarjanM View Drop Down
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Originally posted by _djk_ _djk_ wrote:

The 4" diaphragm on the JBL will allow for more output with less distortion than the 1.75" diaphragm on the BMS in the lower octaves.

Not a 1.75" diaphragm on the BMS. Actually not a diaphragm at all, but annular ring. It has equivalent cone area as a 3 inch dome shaped compression driver.
Marjan Milosevic
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_djk_ View Drop Down
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"Not a 1.75" diaphragm on the BMS.:

BMS says it is 1.75" (44.4 mm Voice Coil).

"It has equivalent cone area as a 3 inch dome shaped compression driver."

I think not.

I own many BMS drivers, they're OK for what they are, but all have their own little quirks.

BMS data sheet for the 1.75" 4555 shows 2nd harmonic at -22dB @1Khz, 1W

JBL 4" shows 2nd harmonic at -40dB @1Khz, 1W

At 10W at 1Khz the distortion rises by 10dB, the 1.75" BMS being -14dB, the 4" titanium being -30dB.

At 10W at 4Khz the distortion rises by 10dB, the 1.75" BMS being -20dB, the 4" titanium being -30dB.

The BMS measures very poorly below about 2Khz, due to its smaller 1.75" diaphragm. The distortion climbs like a rocket on the smaller diaphragm BMS at the 10W level at frequencies below about 1.5Khz.

The 4" titanium remains -30dB at 10W down to 500hz.


Edited by _djk_ - 02 November 2017 at 10:49pm
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MarjanM View Drop Down
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Points: 7816 		Post Options Post Options   Thanks (0) Thanks(0)   Quote MarjanM Quote  Post ReplyReply Direct Link To This Post Posted: 02 November 2017 at 11:29pm
Please calculate the combined cone area inside and outside the voice coil. The result same as like 2.93 inch dome shaped cone.
Distortion graph at BMS is raised for 10db for easier read. So take 10db off your figures.
Still, we are talking about a driver that cost less then the JBL spare diaphragm which brand new original should be at around 200us$.
Those costing 70us$ are aftermarket recones.
How do i know this? I owned quite a big SR417XX rig back in the days. About 40 boxes.

So we are talking here about replacement driver that wont break the bank. 4555 is all of that.
With all it s flaws, it still the best bang for buck out there.

Oh BTW, i am yet to hear someone complaining about distortion in Danleys tops where 4550 is cut at 1KHZ. Pretty much same driver as 4555.
BMS drivers are very tricky to work with and not many have mastered how to tame them. Those who did have boxes praised by others.


Edited by MarjanM - 02 November 2017 at 11:39pm
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gen0me View Drop Down
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Points: 999 		Post Options Post Options   Thanks (0) Thanks(0)   Quote gen0me Quote  Post ReplyReply Direct Link To This Post Posted: 03 November 2017 at 12:20am
Originally posted by MarjanM MarjanM wrote:

Please calculate the combined cone area inside and outside the voice coil. The result same as like 2.93 inch dome shaped cone.

Where have you found info about its cone area?
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Elliot Thompson View Drop Down
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Points: 5175 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Elliot Thompson Quote  Post ReplyReply Direct Link To This Post Posted: 03 November 2017 at 1:39am
Originally posted by jacktheripper jacktheripper wrote:

But I don't care about bass with the SR4731x cabs i'll always be using them with four double 18" subs and the Faital Pro has only a 3" voice coil and as far as i'm aware the voice coile size effects power compression doesn't it? The bigger the voice coil size the lower the power compression generally.



The Faital Pro's TS Parameters are closer to the JBL than the Beyma. The Faital Pro's 3 inch voice coil will offer a more prominent midrange. Larger voice coils are better suited for bass applications. You are not building a cabinet. You are replacing an original driver with an alternative driver. So you want the TS Parameters of the alternative driver to be as close as possible to the original driver.

Best Regards, 
Elliot Thompson
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jacktheripper View Drop Down
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Points: 13 		Post Options Post Options   Thanks (0) Thanks(0)   Quote jacktheripper Quote  Post ReplyReply Direct Link To This Post Posted: 03 November 2017 at 9:11am
Originally posted by Elliot Thompson Elliot Thompson wrote:

Originally posted by jacktheripper jacktheripper wrote:

But I don't care about bass with the SR4731x cabs i'll always be using them with four double 18" subs and the Faital Pro has only a 3" voice coil and as far as i'm aware the voice coile size effects power compression doesn't it? The bigger the voice coil size the lower the power compression generally.



The Faital Pro's TS Parameters are closer to the JBL than the Beyma. The Faital Pro's 3 inch voice coil will offer a more prominent midrange. Larger voice coils are better suited for bass applications. You are not building a cabinet. You are replacing an original driver with an alternative driver. So you want the TS Parameters of the alternative driver to be as close as possible to the original driver.

Best Regards, 

Ah ok thanks.
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