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FLH design Sensitivity compared to Quake, Psycho .

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psychotea View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote psychotea Quote  Post ReplyReply Direct Link To This Post Posted: 18 November 2022 at 3:56am
Ok, so I spent some time building a rough simulation of the HessBH in hornresp. @Nakwa I'd be curious to see how far out I was in the end!
Out of curiosity, I also modelled a B&C 18DS115. I was able to achieve a roughly 2db sensitivity improvement from 35 to 80hz, but there are a few caveats:

- The compression ratio is quite high at 3.75 (vs 1.8 in the original model) -- again I'm not sure if this is acceptable for modern drivers. The loading on the driver should be fairly even considering the throat chamber (S1-S3) is rectangular. With that said 1.8 is relatively low (I think?) so there might be some room for improvement there in the original design(?)
- Volume is increased by ~25L -- but this isn't a big deal at ~4%
- Cost: the B&C driver is about 50% more expensive (£525GBP) - but whether this is worth it is up to the builder :P

I've attached all the hornresp data here: https://imgur.com/a/vTuKA1F

Would love to know everyone's thoughts :-) 
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VECTORDJ View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote VECTORDJ Quote  Post ReplyReply Direct Link To This Post Posted: 18 November 2022 at 10:38pm
Smile

Edited by VECTORDJ - 01 December 2022 at 4:25am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote psychotea Quote  Post ReplyReply Direct Link To This Post Posted: 30 November 2022 at 2:16pm
Played around a bit with the "Compound Horn" design type in hornresp. Using an offset driver in a classical horn I wasn't really able to see the improved low end extension (it was there, just very very minimal), however the CH poses some interesting gains. 

The idea is effectively to have two horns, the main one from the front of the driver as normal, and a smaller separate horn originating from the back of the chamber.

Throwing some quick numbers together I was able to come up with http://https://imgur.com/a/HvXqngO - this. Black line = CH, grey line is my previous FLH design. Sensitivity is 1w/1m in half space (2Pi). This is using the same B&C 18DS115 driver. You can see f0 is about 4hz higher (37 vs 33), however sensitivity is vastly improved ~4dB, and this enclosure is around 110L smaller (670L vs 780L); so the f0 could likely be dropped to match in a comparably sized enclosure. The compression ratio is also a much more reasonable 3.13:1, versus 5:1 in the FLH design.

One caveat is you can see there is a sharp dip at 70hz, I assume this is some form of cancellation from the two horn paths. There is also a bit more of a "sag" between 43-50hz than I'd like (most dnb basslines sit around 43hz), however this does smooth out http://https://imgur.com/a/BGxIm4q - once you scale up to 4 boxes. In a stack of 4 the f0 point also drops to around 35hz with f3 around 31. 

The other thing is I'm not at all sure how this type of enclosure sounds. The main reason I am a big fan of sealed FLH (and less of a fan of TH) is they have a very "tight" but aggressive sound (I assume this stems from the fact that the driver sits in a sealed chamber). On the other hand, I find TH to have a less punchy/more "loose" sound -- I'm not sure if this compound horn design would suffer the same issue. With that said, power handling can potentially be increased, as there would be some airflow into the driver chamber - sealed FLH tent to get preeeeety toasty. 

Does anyone know of any designs based around this CH principle? I saw some early stuff from the paraflex guys, but nothing concrete, and it seems those sketches don't use a flared horn.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote levyte357- Quote  Post ReplyReply Direct Link To This Post Posted: 30 November 2022 at 2:22pm
Playing around with FLH design, using 15" driver, seems bit of a nom starter to me.

Most 18" FLH designs struggle to get below 50hz (in reality, not a sim), with a single cab.

WSX being the best exception, I know.
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