BMS vs Celestion |
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Cheekybox
Registered User Joined: 04 October 2014 Location: Smoke Status: Offline Points: 104 |
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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 Cheers
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Cheekybox
Registered User Joined: 04 October 2014 Location: Smoke Status: Offline Points: 104 |
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Really struggling to find any info on the celestion.
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csg
Old Croc Joined: 17 September 2007 Location: bedford Status: Offline Points: 6086 |
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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.
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“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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kipman725
Registered User Joined: 02 September 2020 Location: Warrington Status: Offline Points: 231 |
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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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APC321
Young Croc Joined: 24 August 2013 Location: West Midlands Status: Offline Points: 684 |
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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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kipman725
Registered User Joined: 02 September 2020 Location: Warrington Status: Offline Points: 231 |
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ah sorry the link didn't appear, this is the thread I was referring to: |
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snowflake
Old Croc Joined: 29 December 2004 Location: Bristol Status: Offline Points: 3121 |
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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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kipman725
Registered User Joined: 02 September 2020 Location: Warrington Status: Offline Points: 231 |
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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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snowflake
Old Croc Joined: 29 December 2004 Location: Bristol Status: Offline Points: 3121 |
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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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kipman725
Registered User Joined: 02 September 2020 Location: Warrington Status: Offline Points: 231 |
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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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snowflake
Old Croc Joined: 29 December 2004 Location: Bristol Status: Offline Points: 3121 |
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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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Cheekybox
Registered User Joined: 04 October 2014 Location: Smoke Status: Offline Points: 104 |
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Have you seen the horn this was designed for?
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