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BMS vs Celestion

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Cheekybox View Drop Down
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    Posted: 12 October 2020 at 9:54pm
Mounted on a 90x40 horn, does anyone have an opinion on the BMS 4590 vs the Celestion Axi 2050?

It would not be played too low, i think in the region of 500

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Cheekybox Quote  Post ReplyReply Direct Link To This Post Posted: 13 October 2020 at 6:34pm
Really struggling to find any info on the celestion.
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Post Options Post Options   Thanks (1) Thanks(1)   Quote csg Quote  Post ReplyReply Direct Link To This Post Posted: 13 October 2020 at 7:06pm
The celestion is a highly expensive unit, I'm not aware of it making its way into many boxes yet. I suspect from looking at the data sheets it will perform very well. 

Ive used and built with BMS 4592 and they are highly capable with corrective EQ. The lowest I've run them is 680Hz.
“The fact is this is about identifying what we do best and finding more ways of doing less of it better”
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Post Options Post Options   Thanks (1) Thanks(1)   Quote kipman725 Quote  Post ReplyReply Direct Link To This Post Posted: 14 October 2020 at 2:49pm
loads of information here:
Also there at least used to be a special discount if you bought this book on the axi2050.

The driver has a 5" diaphragm so low end performance is going to be great for a compression driver.

Also if you search through this thread there are some presentations explaining the decoupling of the mechanical and acoustical modes which allow such a large diaphragm to extend high in frequency.



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Post Options Post Options   Thanks (0) Thanks(0)   Quote APC321 Quote  Post ReplyReply Direct Link To This Post Posted: 14 October 2020 at 3:57pm
Checked out the link..looks like an interesting book.

But £122. That's more expensive than any book I have ever bought.
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Post Options Post Options   Thanks (1) Thanks(1)   Quote kipman725 Quote  Post ReplyReply Direct Link To This Post Posted: 14 October 2020 at 4:24pm
ah sorry the link didn't appear, this is the thread I was referring to:


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Post Options Post Options   Thanks (0) Thanks(0)   Quote snowflake Quote  Post ReplyReply Direct Link To This Post Posted: 14 October 2020 at 5:23pm
every octave you decrease the horn cutoff frequency you reduce the power that can go through the throat for a given distortion level by a factor of four. 300Hz is two octaves below 1.2kHz so 16 times less. increasing the throat area by using a 2" instead of a 1.4" only gets you back to 8 times less power limit. you need multiple bands with appropriate horn loading to get loud and clean - not sure I understand what this celestion driver is for. trying to get more than four octaves out of one driver is just running up against the laws of physics.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote kipman725 Quote  Post ReplyReply Direct Link To This Post Posted: 14 October 2020 at 5:38pm
If you look at the classic M200 with 2" throat distortion is still good down to 400Hz:
Going to the larger throat M4 (4") the distortion is not rising till below 200 Hz:

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Post Options Post Options   Thanks (0) Thanks(0)   Quote snowflake Quote  Post ReplyReply Direct Link To This Post Posted: 14 October 2020 at 6:44pm
Originally posted by kipman725 kipman725 wrote:

If you look at the classic M200 with 2" throat distortion is still good down to 400Hz:
Going to the larger throat M4 (4") the distortion is not rising till below 200 Hz:



the throat distortion is at the high frequencies. Looks pretty much exactly what my chart in Olson predicts. 10% distortion at 10*cutoff at 1 acoustic watt per cm2 of throat.

Community recommends both drivers are used over three octaves.
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Post Options Post Options   Thanks (1) Thanks(1)   Quote kipman725 Quote  Post ReplyReply Direct Link To This Post Posted: 14 October 2020 at 11:28pm
So to me this seems more an argument about horn design than compression driver design as your talking about the flare rate limitations required for low frequency loading?

In the axi2050 the phase plug is at the throat unlike say an JBL 2461 where there is a section of horn incorporated into the driver before the throat.  Obliviously the phase plug still has an internal horn expansion that would have a flare rate but I wonder if (as such drivers didn't exist in that time) that charts from Olson are predictive for such a driver?

Personally I would like to see better data in general from compression driver manufacturers as its pretty difficult to make an educated choice from the limited data provided, at least something like this would be much better:
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Post Options Post Options   Thanks (0) Thanks(0)   Quote snowflake Quote  Post ReplyReply Direct Link To This Post Posted: 14 October 2020 at 11:41pm
Originally posted by kipman725 kipman725 wrote:

So to me this seems more an argument about horn design than compression driver design as your talking about the flare rate limitations required for low frequency loading?

In the axi2050 the phase plug is at the throat unlike say an JBL 2461 where there is a section of horn incorporated into the driver before the throat.  Obliviously the phase plug still has an internal horn expansion that would have a flare rate but I wonder if (as such drivers didn't exist in that time) that charts from Olson are predictive for such a driver?

Personally I would like to see better data in general from compression driver manufacturers as its pretty difficult to make an educated choice from the limited data provided, at least something like this would be much better:


compression drivers have been good enough for several decades that the limiting factor is the horn. no matter what they do in the driver exit it is still going through a throat that either loads the driver at low frequencies and distorts HF at high volume, or doesn't load at low frequencies and throws away the extra bandwidth the driver is capable of.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Cheekybox Quote  Post ReplyReply Direct Link To This Post Posted: 15 October 2020 at 3:00pm
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