Dual 15" mid/highs upgrade |
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Jack_The_Ripper
Registered User Joined: 04 March 2018 Status: Offline Points: 214 |
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What about 36db/oct Linkwitz Riley on the lower end of the compression drivers and upper end of the 15" drivers? With crest factor I have Steinberg Wavelab Elements 9.5.
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Hemisphere
Old Croc Joined: 21 April 2008 Status: Offline Points: 2272 |
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Yes that's what I would expect. I zoomed in on some sections of heavy dub tracks where the strongest part has long full notes run slightly into clip to try and understand the actual restrictions (if any) of Powersoft style reserve power amps in real world conditions. It's always less of an issue than people expect. Extended dub notes or similar are overwhelmingly the main cause of low crest factor, anything which has gaps in it has the crest factor determined more by the gaps than anything. Plus MC mic screaming. I don't think anyone ever intentionally puts long extended clipped mids into music but maybe I'm listening to the wrong music
I can understand the concern as a system operator, that some totally convention-busting track will emerge that puts all these so called musical/technical 'rules' aside and manages to sound enjoyable to some audiences in the process (think how many times that's happened!), and if they've not adequately prepared for that then bye-bye drivers ('buy, buy drivers' following soon after). An RMS limiter wouldn't be acceptable in that case as it would just dip the overall volume by a few dB, ruining the music as it was meant to be enjoyed, but if a rig ever finds itself in a situation like that it would probably be best for all concerned if the volume really did dip a few dB!
Edited by Hemisphere - 17 June 2018 at 9:59pm |
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Conanski
Old Croc Joined: 26 January 2006 Location: Ottawa, Canada Status: Offline Points: 2545 |
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Do you have a way of measuring your systems response in the frequency and time domains? Crossover selection is about tradeoffs, steeper slopes offer more driver protection but introduce more phase shift. Even order filters(12dB,24dB,48dB) sum flat and produce manageable phase shift while odd order filters don't. But those odd order filters can be of use if you know the drivers raw response, when combined together you may end up with the results you want, but failing that a 24dB filter is the best compromise.
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Jack_The_Ripper
Registered User Joined: 04 March 2018 Status: Offline Points: 214 |
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I have the RTA built into the dbx Driverack PA2 but i've heard it's crap.
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godathunder
Old Croc Joined: 19 July 2004 Location: wicklow Status: Offline Points: 1834 |
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surely the problem with any 15" up past the 1k region is going to be dispersion rather than frequency response on axis. It may sound fine in front of the speaker but Id expect a significant hole in the upper mid as you wander off to the sides
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LOUDER THAN LOUD
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Hemisphere
Old Croc Joined: 21 April 2008 Status: Offline Points: 2272 |
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Yes, 1KHz is probably about the most you want to cross at to minimise dispersion issues. Less, ideally. The same is true of most 12's though.
RCF unfortunately don't publish off-axis response, but Faital publish 45 degree plots so you can see how the recommended 15fh530 http://www.faitalpro.com/en/products/LF_Loudspeakers/product_details/index.php?id=151060110 (I assume they meant 530 as there is no 15fh560) performs vs the 12" midbass driver, the 12hp1020 http://www.faitalpro.com/en/products/LF_Loudspeakers/product_details/index.php?id=201050110 Not much in it above 1KHz (actually on second glance there is quite a bit in it..the 12 has a hole of about 7dB and the 15 one of 12dB in the same place). The 12 does a little better in the 500-1KHz range but nothing to shout about, a dB or two. Steep slopes and low cross necessary - 1.5KHz as suggested earlier is not a good idea..a lot rests on the limitations of the HF horn in these cabs. If they can't play low you either take the hit on dispersion or rethink the whole thing.
Edited by Hemisphere - 18 June 2018 at 11:17am |
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odc04r
Old Croc Joined: 12 July 2006 Location: Sarfampton Status: Offline Points: 5482 |
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Metal guitarists would like a word!
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Elliot Thompson
Old Croc Joined: 02 April 2004 Location: United States Status: Offline Points: 5176 |
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150 watts is more than enough for any compression driver for compression drivers are not rated for a lot of power once you choose not to use an external capacitor or crossover network after the amplifier. There are many that rather use more power which, can be based anywhere from not having anything smaller in terms of wattage in amplification, or just wanting to have a lot of headroom at their disposal. The above scenario will always have the amplifier loafing due to the efficiency of the compression driver/horn combination. I tend to cross my compression drivers lower than the majority and roll off my cone drivers higher as I rather have the cone and compression drivers work together as team within the 1 kHz to 2 kHz range. My aim is more High Fidelity results in which, you may be looking more to wards a sharper ear piercing results. So what I post below is more to wards High Fidelity results. Roll off the RCF MB 15N 405 at 2 kHz (-3 dB point) Roll off the Eighteen Sound ND3T at 800 Hz (-3dB point) providing your horn can play 800 Hz. The above will allow both drivers to share the work within the 1 kHz - 1.5 kHz range. If you are looking for a sharper response roll off the RCF MB 15N 405 lower and cut off the Eighteen Sound ND3T higher in addition to, using steeper crossover slopes (24 dB, 36 dB, 48dB and/or higher). It really boils down to listening to the performance of the loudspeakers using a high quality Techno track (In your condition) and tuning to taste. Best Regards, |
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Elliot Thompson
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Jack_The_Ripper
Registered User Joined: 04 March 2018 Status: Offline Points: 214 |
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Thanks Elliot mate.
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Hemisphere
Old Croc Joined: 21 April 2008 Status: Offline Points: 2272 |
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The point I made earlier about ASDR envelopes necessarily having a 'bite' followed by a drop in amplitude to be percieved as louder goes for metal guitar also. It's a fair point though, badly mixed/produced metal could pose a risk.
Edited by Hemisphere - 19 June 2018 at 5:59pm |
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