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FLH design Sensitivity compared to Quake, Psycho . |
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psychotea ![]() New Member ![]() Joined: 03 September 2020 Status: Offline Points: 7 |
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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 ![]() Registered User ![]() ![]() Joined: 11 June 2006 Location: United States Status: Offline Points: 492 |
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![]() Edited by VECTORDJ - 01 December 2022 at 4:25am |
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psychotea ![]() New Member ![]() Joined: 03 September 2020 Status: Offline Points: 7 |
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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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levyte357- ![]() Old Croc ![]() ![]() Joined: 27 July 2012 Location: UK, South East Status: Online Points: 8074 |
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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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Global Depopulation - Alive and Killing.
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coolboarder ![]() Registered User ![]() Joined: 23 June 2010 Location: Germany Status: Offline Points: 29 |
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I continued on the FLH design.
I dropped a little the B&C 18DS115 since the max SPL is anyway limited by the excursion. Because of large excursions, I decided to continue with the BMS 18N862 but also the RCF 18N405 as in the HESSBH seems to work nicely with almost no modifications. As psychotea wrote, I don't really see the described low frequency enhancement from the HESSBH design in hornresp. Maybe I am not getting it, but anyway, with the classical design I can see 30Hz now. I want to stay below 700l in volume. Following just a documentation of the recent hornresp output. The max SPL is wideband above 150dB (1xpi, 4 speakers) and is higher compared to the older PD 1850 mainly due to higher excursion as seems to be possible with the BMS driver. Please correct me if I am wrong. Edited by coolboarder - 08 June 2023 at 11:36am |
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smitske96 ![]() Young Croc ![]() Joined: 16 February 2016 Location: The Netherlands Status: Offline Points: 1034 |
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While the BMS has a high xmax on the spec sheet. That does not mean it is in any form linear to that point. If you have lower BL to begin with, you end up with less control during the end of travel, compared to a higher BL driver.
In practise such loading keeps travel in check, and you will run out of thermal capabilities before excursion. There is a video on yt with the DSL BC218 which shows it. Besides all that, I doubt the 862 cone would survive such loading. Its most suited for BR or CB purposes normally. In practise such
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Xoc1 ![]() Registered User ![]() Joined: 15 October 2012 Location: Devon UK Status: Online Points: 354 |
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Why Sims in 1 x Pi Do you have a massive wall that you will be using directly behind the stack? If just on the ground 2 X Pi then you are simulating the equivalent of 8 cabinets which is helping the LF extension somewhat with a FLH design. The red line on your Sim, being a displacement limit I guess, suggests a lack of a High Pass filter? |
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levyte357- ![]() Old Croc ![]() ![]() Joined: 27 July 2012 Location: UK, South East Status: Online Points: 8074 |
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Good point there..
Maybe a good idea to look at SBH, Invader, WSX, and refine one of them. Would think WSX is pretty much perfect, apart from compression being too high.
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Global Depopulation - Alive and Killing.
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