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Is this a good idea? are FLHs bad in 2020? |
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mstep77 
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 Posted: 27 May 2020 at 8:35am |
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Or you could make it in 2 peices. There was an 18 sound design like this I think
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citizensc
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Joined: 16 October 2015 Location: Perth,Australia Status: Offline Points: 532 |
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Posted: 27 May 2020 at 10:21am |
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Honestly, the SBH doesn't even really sim that well, it isn't very sensitive and isn't what i'd call flat. Here is a sim of it and a real life measurement to compare, they do have a bit in common.  This is 4 horns coupled at 8ohm, 2.83v  The reason i'm developing something totally new is I have always felt a DIY FLH that fits between the size of a punisher and a WSX that plays lower than a punisher with greater sensitivity. Basically a <40hz FLH that is a sensible size. Maybe it cant be done but I haven't given up yet. I am working on a new design in hornresp that's about 80L smaller than the previous attempt and has a similar response. |
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citizensc
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Joined: 16 October 2015 Location: Perth,Australia Status: Offline Points: 532 |
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Posted: 27 May 2020 at 10:30am |
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Thinking about it now, I cant remember ever standing in front of a big pile of reflex and being wowed by the sound, D&B is pretty much the only brand big PA companies in Perth use, for dance music I think they are the most boring sounding systems. I have a plethora of fond memories standing in front of big piles of both BPH and FLH, DIY and commercially produced alike. As far as application goes, dance music focused sound systems, although, right now I don't have the means to build a bunch of FLHs (im living in an apartment in Melbourne finishing my masters). I'm designing it as a learning experience/something to fill the time during lock down. Got to have a hobby in times like these. If someone is interested in the final design, they can beta test it. |
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citizensc
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Joined: 16 October 2015 Location: Perth,Australia Status: Offline Points: 532 |
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Posted: 29 May 2020 at 6:19am |
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After a lot more experimentation, I have come up with something I am a lot happier with, even a little proud of.
I have shortened the horn from 280cm to 260cm, changed from the 15DS100 to the 15DS115 as it has more xmax, much better excursion behaviour and responds better to a tighter horn. Compression ratio has decreased to about 3:1, about the same as the punisher which I think should be fine considering the 15DS115 has an enormous MMS for a 15 inch driver, suggesting the cone is very tough. The good: -The cab is 910x1010x536mm or 492L -Weighs ~70kg including driver and bracing -Should be simple to build -Has an F3 of 36hz -Can take a huge amount of power For reference a WSX is 572L, SBH is 622L, 1850 horn is 456L, Punisher is 285L and the TH18 is 420L To my knowledge there are no widely circulated plans for sensibly sized FLHs that have an F3 in the mid 30s. The bad -Not sure if heat buildup in the rear chamber will be an issue. The chamber is about twice the volume of a punisher and has a lot more surface area so it may be okay. Anyway here it is Bracing to be added, and yes it looks a lot like a punisher, it wasn't deliberate, I promise!    109.54v @ 2ohm (1500 watts per driver, 4 cabs)  1500 watt (109.54v) per driver  |
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smoore
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Joined: 30 March 2011 Location: N.Devon Status: Offline Points: 937 |
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Posted: 29 May 2020 at 11:19am |
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Nice man good work really interested to see how this turns out! Maybe look at metal access panels for heat exchange?
One thing I'd suggest considering in your freq response, I often find horn resp sims seem to exaggerate the Fs 'bump' and often the real response is sort of leaning back from left to right (rising response with frequency) compared to sim. Quite a few examples of this if you check sim vs measurements (The SBH above). I would try to aim for a bigger response around 40hz and lower around 100hz if I wanted a flat response. Just my 2 cents and may well be completely wrong but thought it was worth mentioning! Good luck bro it's a good design project!
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Xoc1
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Posted: 29 May 2020 at 10:18pm |
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So you show a 3 segment sim with a 4 segment schematic, You changed OD to Nd but show a drawing that is an OD horn You show a FR with no high pass filter and over excursion. Have you tried to apply a filter to keep excursion down to x-max? If you do you you will find it will take a load of power but I don't think you will like the acoustic response so much. Quite a lot of ripple in the pass band. CAD looks OK but how are you calculating the path & horn widths? - Does the internal volume match the sim or is it out by a country mile? Keep going! |
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Keen
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Joined: 30 May 2011 Location: Brisbane, Aus Status: Offline Points: 1203 |
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Posted: 30 May 2020 at 1:05am |
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^^this
I'm not getting 50L vrc, which I suspected at first glance. In reality more like 35 which is too low. hits GD out the park. Aim to keep GD within a 20ms fluc across passband, lower the better imo. Basically, what you're going to find when you refine and improve the design/perfomance of bass horns is that you end up with enough space for an 18. It starts to hit the sweet spot in terms of sim data, in turn you get a better understanding of what's happening between the rear chamber/driver/horn etc. FLH are impedance matching devices. They, as all cabs do to a certain extent, change the TS parameters of the drivers under load, which in turn effects current draw and so on. Therefore the drive unit/enclosure/amp start operating as one complex system unique unto itself. The quality value (qtc) exhibitied by the drive unit/enclosure as a whole can be calculated and understanding this value can be invaluable info for predicting how drivers will behave and sound. These days because the pass band of bass horns is so small, you can pretty much get away with using any driver and it sounding ok. Driver selection becomes more important when the pass band is covering more octaves. But IMO, if you're aiming to acheive acceptable results when chucking big power into big bucks drivers in long horns, you want to make sure you have a least some idea of what's going on in the engine room: i don't fully understand this yet: Edited by Keen - 30 May 2020 at 10:21am |
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citizensc
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Joined: 16 October 2015 Location: Perth,Australia Status: Offline Points: 532 |
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Posted: 30 May 2020 at 1:02pm |
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Is this maybe due to directivity? Higher frequencies may beam a little more and be more concentrated on axis? id imagine the opposite would be true standing behind the speakers.
The three segments are coloured red, purple and green, note the changes in expansion rate. Yes this is an OD horn, I experimented in horn resp with moving the volume of the OD horn segments to the VTC. It sims literally exactly the same and frees up two horn segments to play with. If you don't believe me, I can send you some examples. VTC is the yellow section + the volume of the cone. 
Sorry to bring up an old post of yours, I do a lot of reading of old forum posts in my research. In a post talking about hornresp you said "When looking at the power rating for xmax the figure is going to be masively pessimistic - Most drivers will have approx 3dB thermal compression, and as you say not be playing a sine wave signal." - https://forum.speakerplans.com/hornresp-diaphragm-displacement_topic101133.html Do you still hold this belief? the thinking seems sound to me. Simming other cabs suggests this is pretty tame. An 1850 horn hits 15mm at 40hz with 89.44v for example. Here is 109.54v, well within xmax and a relatively low high pass.  Here is 154.92v and a reasonable high pass, I suspect in the real world this would still be within xmax despite giving the driver a real spanking.  I plan to put the driver hatch in the mouth of the horn, a little unconventional I know but with a large 6mm aluminium panel it should aid with cooling, especially with the air movement. I think, if done right, this cab has real power handling potential.
What would you call too much? there is about 3db from peak to trough. I know some other cabs are far worse than this *cough* SBH.
The internal volumes are very close. Here is a pic of the method I used to fold the horn. I literally drew the straight horn using the data from the export tool in hornresp, cut it up and folded it. The only bits im unsure about are the back corners. I have cut in to the horn path a little aiming to preserve the volume of that section, is that the correct way of going about it? 
What do you mean you are not getting 50L vrc? as in you are measuring it from my drawing? or are you using a formulae from this paper?http://leachlegacy.ece.gatech.edu/papers/HornPaper/HornPaper.pdf I'm not sure what you mean. I can assure you the rear chamber in that drawing is not 35L, sketchup can measure it quite easily. What is considered acceptable group delay? I noticed reducing Vtc greatly reduces it And thanks heaps for the link to this thread https://forum.speakerplans.com/topic102307_post1014911.html#1014911 there is some gold in it, especially that paper linked above, may take me a bit to get my head around it, especially as I only know about 1/4 of those symbols mean with out checking the glossary. Thanks a lot for your help guys, I am learning A LOT! Edited by citizensc - 30 May 2020 at 1:07pm |
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Keen
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Joined: 30 May 2011 Location: Brisbane, Aus Status: Offline Points: 1203 |
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Posted: 30 May 2020 at 3:03pm |
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i drew it out on graph paper, minus driver volume, looked like 50L was a bit optimistic. But if sketchup calculates, it should be right. One thing I would add is a double baffle, and that will eat some volume.
acceptable group delay depends on the bpm of your source, as it goes beyond 140's I prefer to keep it below a 25ms fluc across the passband. sort of splitting hairs but good to keep an eye on it
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citizensc
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Posted: 04 June 2020 at 12:50pm |
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Okay, iteration 3 is here. Some major changes and some major improvement yet again.
After reading the Leache paper and playing with the formulae, I have learnt a lot about what kind of drivers work in the kind of horn i'm trying to develop, I have come to the conclusion that the B&C DS drivers are the exact opposite to what i'm looking for. The motor is too strong, suspension too tight to play low in a compact horn. The driver I am going with now is the 15BG100-8, it has a VERY heavy cone, and 14mm Xvar (which according to B&C is the one I should care about), 10.5mm of xmax. It is cheaper than the DS and SW models and should be pretty tough. It is widely available from stores in Europe and the US. An alternative, cheaper driver would be the 15PS100, it is very inexpensive for a sub driver , howerver, it has reduced xmax and power handling. You would still be able to make some serious noise hooking 4 up to an NX6000 if you are working with a tight budget. Anyway the horn chambers are the correct volumes and the horn is reactance annulled properly according to the formulae on the Leache paper. The Horn shape is based on a hyperbolic horn with a T of 0.52. The horn is now a little bit shorter so I should be able to make the cab a little smaller as well. I will wait for feedback before folding it.  It is 240cm long.  No filters, response is MUCH flatter than before, F3 is 36 hz with out a filter, 37 when highpassed at 35hz.  Group Delay is greatly improved, looking at sims for other designs, 25ms appears to be very good.  This is with 89.44v @ 8ohm (1000w) per driver. High passed @ 35hz  |
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Keen
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Joined: 30 May 2011 Location: Brisbane, Aus Status: Offline Points: 1203 |
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Posted: 07 June 2020 at 12:42am |
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now you talkn' hugh!!!
 really well done getting through all that. Doesn't it feel good knowing that the driver you're interested in isn't necessarily the prn star driver at the time. Those BG's will be luuusssh, the T/S params have smooth sub written all over them. It's why the punisher was so successfull, all about the 12.00sw, timeless driver. The data looks great.
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citizensc
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Posted: 13 June 2020 at 6:06am |
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Thanks for the kind words!
After folding the horn about 10 times trying to get the chamber volumes perfect and minimise wasted space I have come up with this. The horn has changed slightly since my last post but it performs very similarly in hornresp, with a slight improvement in sensitivity.  Black = 4 cabs 2.83v @ 8ohm (1 watt), Grey = 2 cabs 2.00v @ 4ohm (1 watt)    The driver hatch is in the mouth by design, it should be sealed with a sheet of 6mm aluminium to aid in cooling. I think this cab should be able to take >1000watts with out issue, putting out >142db continuous with an f3 in the mid 30s with 4 cabs and 145db with 6 cabs ignoring power compression. This should work okay in groups of two but works best with four or more. As I have said previously: -It should be relatively easy to build when compared to other FLH designs. -The size should be manageable, its not tiny like a punisher but its not gigantic either. It is 1050x940x536, and should weigh about 75kg, loaded. -The 15BG100 is very easy to obtain and not enormously expensive when compared to some other designs (it costs a lot less than a pd1850, 18sw115 or 21sw152) -If the 15BG100 is still too expensive, you could load it with a 15PS100, the 15BG100 will be better as the horn was designed for it but the 15PS100 sims with simmilar sensitivity and group delay. I doubt you will find cheaper FLH suitable for PA use than this loaded with the 15PS100. -I think this fits a middle ground not previously filled by DIY FLHs, they either roll off in the mid to high 40s (1850 horn, punisher) or are gigantic (sbh). This horn is a manageable size while also having an f3 in the mid 30s. Let me know what you think! If there are no significant issues I will finalise the design and post it. Edited by citizensc - 13 June 2020 at 6:09am |
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