cARver Posted December 1, 2017 Report Share Posted December 1, 2017 I have been learning about crossovers and slopes but no expert by any means. Can some one confirm the slope of the 9ls 9lsi slopes since the owners manuals don't seem to call it out like the AR9 manual does? I'm guessing here on the 9ls/lsi......... 18db 200 hz woofer? 12db 200 hz lower mid bass? 12db 1100hz mid bass? 12db 5500hz mid dome? 12db 5500hz tweeter or 6dblsi mod? Actual_AR9_crossover_circuit.pdf Link to comment Share on other sites More sharing options...
fedeleluigi Posted February 2, 2018 Report Share Posted February 2, 2018 On 1/12/2017 at 2:47 AM, cARver said: I have been learning about crossovers and slopes but no expert by any means. Can some one confirm the slope of the 9ls 9lsi slopes since the owners manuals don't seem to call it out like the AR9 manual does? I'm guessing here on the 9ls/lsi......... 18db 200 hz woofer? 12db 200 hz lower mid bass? 12db 1100hz mid bass? 12db 5500hz mid dome? 12db 5500hz tweeter or 6dblsi mod? Actual_AR9_crossover_circuit.pdf Without measurements or simulations (in the latter case you also need Thiele ans Small parameters, etc. ) by examining a crossover network you can only say the electrical crossover slopes. On the contrary, what really matters for the sound and to obtain a "flat" frequency response in the crossover region, are the acoustic slopes of each driver response in the crossover region itself (i.e. where the drivers are crossed over). The crossover region is the common region in a louspeaker frequency response in which two (or more) drivers simoultaneously sound. In this region the driver emissions overlap and add together. Obviously also the relationship between the acoustic phases of drivers is of fundamental importance to get a flat frequency response in the crossover region. Moreover, other parameters should be also considered such as the Q-factor and the type of filters (Butterworth, Bessel, Linkwitz-Riley etc.). As regards the acoustic slopes, they depend on the interaction between the elecrical slope of the crossover network and the natural frequency response of the driver. In other words: Acoustic Slope = Filter + Driver Natural Response For instance, in the AR 18 S and 38 S manual, you can read in the specifications (read at "crossover network"): "Highrange has a first order electrical network plus mechanical slope to give a total of 18 dB/octave". http://www.classicspeakerpages.net/library/acoustic_research/post-classic_series_1981-19/post-classic_series_manuals/ar18s_-_ar58s_manual/ar18s_-_ar58s_manual_pg6.html This means that in the AR 18 S and 38 S, the electric slope of the tweeter crossover network is only 6dB/octave (only a cap in series with tweeter) but it adds together with the natural frequency response of the tweeter providing a final acoustic slope of 18dB/octave in the tweeter frequency response at the crossover region. The "mecanical slope" of the 18 S / 38 S tweeter depends on its natural frequency response. So, simplifying a little, what really matters in order to get a "flat" frequency response in the crossover region are the drivers acoustic slopes and phases in the crossover region itself. Said that, as regards AR9 LS electrical crossover slopes, they are: Woofer low pass: 18dB/octave Lower midrange high-pass: 12dB/octave Lower midrange low-pass: 12 dB/octave Upper midrange high-pass: 12dB/octave Upper midrange low-pass: 12dB/octave Tweeter high-pass: 18dB/octave The Ar9 LSI schematic shows some variations. I do think they were made because the new Tonegen units had some little differences compared with the previous drivers. One of these schematic variations concerned the electrical crossover slope in the tweeter crossover network. It was changed into a 12dB/octave high pass filter. Luigi AR9LS Improved crossover schematic Link to comment Share on other sites More sharing options...
ligs Posted February 2, 2018 Report Share Posted February 2, 2018 Here is a nice illustration of the frequency responses of all the drivers in AR90, driven through the crossovers. Link to comment Share on other sites More sharing options...
harry398 Posted February 3, 2018 Report Share Posted February 3, 2018 21 hours ago, ligs said: Here is a nice illustration of the frequency responses of all the drivers in AR90, driven through the crossovers. This is interesting. I am assuming this represents a Fresh speaker, not a older used one with Old caps. This is showing the actual crossover points are Lower than advertised by AR on the AR90. There is a nice Hole there between 800-1200 hz. Seems the 8 inch was sloped out too early.... Where did you find this chart? Are there other charts of say the AR9, and AR9LS that MR Carver opened the thread about? Link to comment Share on other sites More sharing options...
ligs Posted February 3, 2018 Report Share Posted February 3, 2018 I can not recall the original source of this graph because it was a screenshot using Windows 'sniping tool" In terms of the hole between the LMR and UMR, I am not sure it is a problem. Here is a white paper on the design of a modern Revel speaker with a steep crossover slope. Apparently the hole is a part of the design for flat on-axis and off-axis response. Revel is a highly regarded speaker manufacturer and a part of Harmon International with some of the most sophisticated testing and designing capabilities. https://revelspeakers.com/tl_files/catalog//LuxuryCars/Revel/Manuals/Revel_Concerta2_White_Paper.pdf Link to comment Share on other sites More sharing options...
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