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scoop compatible drivers... |
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levyte357- 
Old Croc 
Joined: 27 July 2012 Location: UK, South East Status: Offline Points: 8128 |
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 Posted: 07 June 2017 at 11:50am |
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Recommended chamber & tuning freq, is probably for reflex cab, and anyone worth his salt, will know from TS, you "DO NOT", want to put this in reflex cab, and what the Qes is telling you, about the warmth of sub, this driver, will naturally produce.
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Global Depopulation - Alive and Killing.
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djkeet
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Joined: 26 December 2011 Location: England Status: Offline Points: 462 |
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Posted: 07 June 2017 at 6:40pm |
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I know what your saying Levyte Speakerplans is a learning platform where if you go back far enough you will see where ppl have either contradicted themselves or gleaned from others what they know no one has a monopoly on knowledge some ppl use knowledge to beat ppl with others use it to teach . I agree if you don't know what your doing you could be wasting your cash how many of us have done that.Based on my limited knowledge B&C will be biased towards their own designs and I could see this driver in a specifically tuned cab I.e. Transmission line config or something of that nature. Edited by djkeet - 07 June 2017 at 6:44pm |
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Soundbite
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turbo7
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Joined: 15 March 2009 Status: Offline Points: 233 |
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Posted: 07 June 2017 at 10:47pm |
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An interesting thing about this driver is, that it already looses 50% of its BL product at >14mm of excursion, mathematical x-max is 13mm, that is what B&C say with their "Xvar" value. If we look at the voice coil mag nov 2010 we can see a Klippel measurement of the 18sNLW9600 and its BL curve. I really hope that someone with Klippel Equipment makes a BL curve of the DS18. Then we could see, if the suspension or BL is limiting Xmax. Of course, this is trivial in this case, i am looking forward to a more steep BL curve... it is always a trade off, but i guess the 7 years of engineering in favour helped to beat the 9600
Edit: HOW CAN I INSERT PICTURES ?? WHICH FORMAT WORKS ? I also guess that nonlinearities which are basically "large signal parameters" can not be extracted from "small signal parameters" which represent the TS parameters. Edited by turbo7 - 07 June 2017 at 11:09pm |
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Ricci
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Joined: 13 March 2017 Location: Louisville, KY Status: Offline Points: 69 |
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Posted: 08 June 2017 at 6:28pm |
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The 21DS115-8 was already tested in the Aug 2016 Voice coil.
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Sypa
Young Croc 
Joined: 21 February 2013 Location: Croatia Status: Offline Points: 921 |
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Posted: 08 June 2017 at 7:04pm |
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Where?
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MarjanM
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Joined: 10 February 2005 Location: Macedonia Status: Offline Points: 7816 |
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Posted: 08 June 2017 at 7:14pm |
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Voice coil magazine
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Marjan Milosevic
MM-Acoustics www.mm-acoustics.com https://www.facebook.com/pages/MM-Acoustics/608901282527713 |
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turbo7
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Posted: 08 June 2017 at 10:57pm |
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Nice one Ricci,
i see the 21" and the 18" are totally different design approaches if the numbers are correct.... 21": Xvar = 16,5mm, Xmax = 15mm 18": Xvar = 14mm, Xmax = 16,5mm taken out of B&C official datasheets probably numbers switched by accident... IF numbers of the 18" are switched, it would be a very good sign and the shape of the BL curve would probably be as good as for the 21"  The 21" is a fantastic driver on the bench ! |
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MarjanM
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Joined: 10 February 2005 Location: Macedonia Status: Offline Points: 7816 |
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Posted: 09 June 2017 at 12:32am |
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Bench test is showing quite lower X-max results.
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Marjan Milosevic
MM-Acoustics www.mm-acoustics.com https://www.facebook.com/pages/MM-Acoustics/608901282527713 |
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turbo7
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Posted: 09 June 2017 at 8:57am |
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yes, but 12,7mm excursion when BL and compliance together start to limit the motor is a very good result for a 11mm physical xmax !
The 18" version even has 13mm physical xmax... |
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Ricci
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Joined: 13 March 2017 Location: Louisville, KY Status: Offline Points: 69 |
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Posted: 12 June 2017 at 6:13pm |
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After reading the text again I see that Vance used the physical coil overhang (11mm) and +15% of the coil overhang as the xmax target which is 12.7mm rounded up. Many MFG's use the physical coil overhang + 25% of the gap height, not the coil overhang. That value would be 14.5mm for the 21DS115-8 which is pretty close to the B&C rating. Using the coil overhang rather than gap height for the % adder is odd. The Xvar B&C quote should be based on internal Klippel testing. In the AX/VC test notes it also says that the BL and Kms were both "beyond" the 12.7mm xmax target he set, but it does not state what they actually were? The Klippel testing appears to have been stopped at a 15mm limit only, which is also odd for a driver claiming 15mm xmax. They usually extend the graph to +/-20mm for woofers with 10-15mm claimed xmax. Perhaps it was just an oversight on the graph scaling. I'm not trying to start a conspiracy theory here just noting some things in the review. I have a pair of 21DS115-4's on hand and they certainly seem "useful" to somewhere in the range of 15-17mm one way. Things quickly start to degrade much beyond that point as the coil starts leaving the gap and the suspension tightens up. The 18's appear to have the same motor but the coil wind is 4mm longer so technically they should have a bit more extended BL curve. The 18" surround is also different though so it may be a wash.
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djkeet
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Joined: 26 December 2011 Location: England Status: Offline Points: 462 |
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Posted: 14 June 2017 at 2:02am |
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In line with Ricci comments leading speaker manufacture's such as PD are in favour of LEAP 5 Enclosure Shop to evaluate their drivers as they feel TS params do not appear to give a true account, if this is the case could the data that has been inputted to Hornresp and other modelling programs be slightly out? |
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Soundbite
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odc04r
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Joined: 12 July 2006 Location: Sarfampton Status: Offline Points: 5482 |
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Posted: 14 June 2017 at 8:07am |
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In any manufacturing process there is always a statistical distribution of performance. If I was in the business of building cabs seriously, the TS provided by the manufacturer would only be a rough starting point for me. And even if you were lucky and your unit was bang on the mean, TS are only an indication of small signal performance anyway which is where the difference between theory and real world hammering starts to appear. But if you know your stuff, the TS are a very good indication of potential real world performance.
That's my take on it anyway. |
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levyte357- wrote: