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In the Forum: Horn-Loaded Speakers
In the Thread: Another time aligned 5-way horn project
Post Subject: Not so simple though...Posted by anthony on: 8/14/2015
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 Murataltuev wrote:
 anthony wrote:
This configuration should give somewhere around 109dB @ 20Hz from 15w in room with cone movement of about +-3.5mm.  That is still low excursion, and they are excellent drivers.   
Well, in this case, I also have to try this configuration.109db is what I need to try to keep system running with single amp.What crossover slope are you going to use ?How are you implementing upper bass ?


The maths for the 109dB/15W goes as follows.  According to the datasheet the driver is around 85dB sensitive at 20Hz.  Double the number of drivers three times to 8 and SPL goes to 94dB/1W.  Add the second speaker and we get to 97dB/1W.  Multply 1W four times to get 16W of output and that makes 109dB/16W.  Then we have to add room gain at those frequencies and subtract for the listening distance.  Room gain is unpredictable but we are going to lose 6dB every doubling of distance to the listening position so if we listen at 4m we might lose 12dB which makes the speaker able to produce a maximum of 97dB at a 4m distance with 16W of power applied.  Then there is room gain to add to this number which may take it to 100dB as the listening chair if we are lucky.

Anyway, that may or may not be enough SPL for the size of your room and the size of your amplifiers.  Those particular drivers will take more power than 16W but I guess will probably start to be less than optimal with maybe 80W put through them (Romy would have better insight than I) which would raise the SPL by about 7dB.  Is this loud enough in my case?  I think it just might be.  Is it good enough in your case?  Depends on the size of your room and how far away you sit from the lower bass sources.  I am counting on some room gain in those lower frequencies to raise the SPL droop of the driver and sealed boxes but how much I will get I won't know until I do it, but hopefully I won't have to resort to DSP to get a decent frequency response.

Regarding the other questions you asked, I am basically duplicating Romy's system as my starting point with horns.  If I spend enough time on it I am hoping for a good result.  Personally, I really dig the concept of his DSET amplification and the specialisation of the amplifier to match the frequency range and transducer and sound quality objectives.

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