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BG Horn Mk1 - 36hz Front loaded horn

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KaphaSound View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote KaphaSound Quote  Post ReplyReply Direct Link To This Post Posted: 20 August 2020 at 3:41am
Man holy cow that’s one sexy looking design! You’re using Sketchup correct? Seriously unreal even just the 2pi output looks like it could have some serious extension. Last I checked there was a sharp change in phase around 80hz or so. Is this important or not at all? Also how was the delay response looking here? I’ll be giving this a go by the end of the year without a doubt and will definitely give some different hornresp charts before committing to a final design. I was hoping to have a slightly wider design potentially to have semi decent stereo separation on some mid tops that would rest on top of the subs. Also I see that you still have some dividers up between the two stacks whereas in Danley’s design the combined mouth has no division (this one looks like two horns next to each other rather than one big combination). Any thoughts on how that might differ? I have no doubt the BC format will lead to some very interesting designs all around and again citizensc thanks for all you’ve done here.

Bare with me for the next couple days as work has picked up quite a bit, but I’ll post some more photos and thoughts on this. Maybe one final thought to leave you with is how the curve in the cut of the top sheet lines up perfectly with the mouth flare in the BC218. I could imagine air getting potentially trapped in the current design in the corner right underneath the access panel which would maybe add unnecessary force on the driver (again this is the first plan I’ve contributed to or even loaded into hornresp so take everything I say with a big grain of salt).


Edited by KaphaSound - 21 August 2020 at 1:03am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote citizensc Quote  Post ReplyReply Direct Link To This Post Posted: 21 August 2020 at 6:57am
Originally posted by doller doller wrote:

Great work you two, very interesting stuff. sorry I can't help with the sims bit dumb on that front sorry. 
Correct me if I am wrong but isn't the point of the bc system focused bass. I.e. not so omnidirectional on the dance floor so to speak. So how different would a bass beam sound to bass everywhere if you get what I am trying to say. Can't sim that I guess. This would be an expensive experiment. I am tempted to take a jig saw to my labs and see what happens. maybe a router.
Did the old Celestion boxes with barn doors use the same concept?


I think directivity is a big part of it, I would be surprised if this didn't decrease noise on stage and by doing that it would increase noise on the dance floor. 

I am not familiar with the Celestion you are talking about but I can imagine they would have a similar effect. 

It would be an expensive experiment, on my never ending list of projects id like to try but cant due to my current circumstances id love to build another sound system, if I did i would probably try this and measure it. 

If you do end up cutting your labs up, id love to see the results, my mouth is watering thinking about the graphs, no pressure though, don't do anything you will regret! 

Originally posted by KaphaSound KaphaSound wrote:


You’re using Sketchup correct? 

Yep, I have tried about 6 different software packages for designing speakers, I keep going back to sketchup because its so simple and fast. It may lack features but I can draw a bass horn in about 10 min if you give me a 2d drawing. I am a rapid iteration kinda guy, rather than get something right the first time I will iterate it about 20 times and zone in on what I think is optimal. 

Originally posted by KaphaSound KaphaSound wrote:


Last I checked there was a sharp change in phase around 80hz or so. Is this important or not at all? Also how was the delay response looking here? I’ll be giving this a go by the end of the year without a doubt and will definitely give some different hornresp charts before committing to a final design.

If you are talking about rapid changes from -180 to 180 degrees, this isn't actually a rapid change, it is just the graph wrapping around from bottom to top rather than continuing to extend downwards, it just makes the graph easier to read. See the images below for more detail, I also always post my hornresp inputs so if you are curious about any data I haven't shown, you can always plug the numbers in and have a look.

As far as this design goes, I am literally just cutting a chunk out of the standard BG horn, you can see I haven't changed the bracing at all, if you were to actually build this I would cut curves in the bracing and the panels where the cabs meet to make it a bit more 'aesthetic'. 


After some playing in hornresp, I have decided the hole I cut is too small, 1500cm^2 per BG horn seems to be the point of diminishing returns. Here are some sims with the bigger hole. 



BG horn grey, with the BC mod black, both 2pi

BG horn Grey, BC mod black, BG = 2pi, BC mod = 1pi

BG horn Grey, BC mod black, group delay may look bad with the BG mod but in the 40-50hz range its actually reduced and i'm not sure you can actually hear 35ms of group delay at 35hz

BG horn grey, BC mod black, as I said at 80hz that isnt a sudden change in phase, the plot is just going off the bottom of the graph and wrapping around to the top. 




Like I have said previously, I think 1pi is a bit optimistic, I suspect reality is some where between 1pi and 2pi. 



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Post Options Post Options   Thanks (0) Thanks(0)   Quote snowflake Quote  Post ReplyReply Direct Link To This Post Posted: 21 August 2020 at 12:53pm
to sim the effect of the four speakers stacked together you can add a final horn section that expands to 4m2 or whatever it is over a very short distance and model it in 2pi. still not exact unless horn mouth is on the floor but close. as you have already used all the hornresp sections you would have to merge some of them together to free up section 4.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote citizensc Quote  Post ReplyReply Direct Link To This Post Posted: 21 August 2020 at 1:36pm
Originally posted by snowflake snowflake wrote:

to sim the effect of the four speakers stacked together you can add a final horn section that expands to 4m2 or whatever it is over a very short distance and model it in 2pi. still not exact unless horn mouth is on the floor but close. as you have already used all the hornresp sections you would have to merge some of them together to free up section 4.


I was thinking about this, I have already done some merging to free up a segment for the BC hole thing. I might free up another and try it tomorrow. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote bass*en*mass Quote  Post ReplyReply Direct Link To This Post Posted: 24 August 2020 at 10:50pm
..if things go well this week i might finally manage to finish the proto extensions of our new custom 18" FLHs.. :)
similar to yours, 4x 36hz f3 horns coupled to an extension of more or less unknown tuning..
250x180cm mouth in our case+, substantial cross section area/volume - curious myself what exactly might happen :)
will report back asap!

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Post Options Post Options   Thanks (0) Thanks(0)   Quote KaphaSound Quote  Post ReplyReply Direct Link To This Post Posted: 25 August 2020 at 5:45am
I think David McBean and others have shown that aggregating multiple sections into one has a negligible effect on the total response curve, so I think hornresp for these designs could still be quite accurate. The only thing that isn’t certain is where the response lies between 1 and 2pi. Correct me if I’m wrong but even if a face only reflects 60 percent of a wavelength those gains should still be significant at that frequency shouldn’t they? Or is it an all or nothing scenario? Either way with the current response curve it actually looks like the higher sub frequencies could use a boost for once so these frequencies should definitely see some improved sensitivity from the size of the face. Also citizensc is there a reason you are using conical segments? I’ve definitely also read that parabolic is better at simming folded horns due to two walls remaining constant/ not expanding (until the end of this particular design at least).

Edited by KaphaSound - 25 August 2020 at 8:08am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote citizensc Quote  Post ReplyReply Direct Link To This Post Posted: 25 August 2020 at 11:29am
Originally posted by bass*en*mass bass*en*mass wrote:

..if things go well this week i might finally manage to finish the proto extensions of our new custom 18" FLHs.. :)
similar to yours, 4x 36hz f3 horns coupled to an extension of more or less unknown tuning..
250x180cm mouth in our case+, substantial cross section area/volume - curious myself what exactly might happen :)
will report back asap!



Sounds interesting, you should start a thread for the project, id love to read it! 

And I would love to what impact the extensions have. 


As far as simming this in hornresp goes, I will sim it in AKABAK 3 and report back when I get time. I think this will give a far more realistic result.  


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Post Options Post Options   Thanks (0) Thanks(0)   Quote citizensc Quote  Post ReplyReply Direct Link To This Post Posted: 03 September 2020 at 4:31am
I have moved the BC conversation to another thread, just to keep this thread a little more focused on the BG horn. https://forum.speakerplans.com/bc-horns-from-standard-flhs_topic105665.html


And for those that are interested, here is how the BG horn compares to the Punisher in AKABAK 3. Please keep in mind that the Punisher is a more compact cab. 

Both are 1.41v @ 2 ohm, 4 horns coupled in 2 pi measured from 1m. 

Punisher in red, BG in blue
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Post Options Post Options   Thanks (0) Thanks(0)   Quote dnbpc Quote  Post ReplyReply Direct Link To This Post Posted: 04 February 2021 at 4:06pm
Has anyone built a prototype of this design yet? Would be interested in hearing the real life results as eyeing it up for a future build. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote citizensc Quote  Post ReplyReply Direct Link To This Post Posted: 05 February 2021 at 7:33am
Originally posted by dnbpc dnbpc wrote:

Has anyone built a prototype of this design yet? Would be interested in hearing the real life results as eyeing it up for a future build. 


I've had multiple people people express interest in building the BG horn but I don't know of anyone following through. 

I am pretty confident it would make a lot of bass when used correctly (in multiples) as this has been shown in both conventional sims and BEM sims which work very differently. It's also unlikely to be a driver killer due to lowish compression and a tough driver with a heavy cone. 

The only thing I cant be completely confident about is the tonal characteristic, id imagine it would have a relatively warm low end due to using a driver with a qts above 0.4. I also speculate that it would be quite punchy simply out of virtue of being a front loaded horn. 

If you do end up building some, don't hesitate to hit me up, I'm happy to help with any issues you might encounter in the build.




Edited by citizensc - 05 February 2021 at 7:54am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote dnbpc Quote  Post ReplyReply Direct Link To This Post Posted: 04 March 2021 at 7:21pm
Thanks I’m still thinking it over at the minute, the thought of events coming back has kicked me into gear again.

Did I read on the earlier thread the the b&c 15ps100 was a potential driver or did I imagine it? I’ve got two sat around so may be a good fit.


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Post Options Post Options   Thanks (0) Thanks(0)   Quote citizensc Quote  Post ReplyReply Direct Link To This Post Posted: 05 March 2021 at 1:38am
The 15PS100 could work well. You wont hit the SPL of a 15BG100 as it only has 6.5mm of Xvar compared to the 14mm of the 15BG100 but it should still give you a good idea of what they sound like. 

Here are some AKABAK 3 sims of some different drivers in the BG horn, please keep in mind these are on axis measurements, not power response measurements like hornresp outputs. I added in the 15SW115-8 to show why putting a driver with lowish Qts in this horn may be a bad idea.

I also have no idea if any of these drivers will actually fit in the chamber, will leave that to others to figure out. 

All measurements are 4 cabs with 1.41v @ 2ohm measured from 10m, scaled to 1m in 2pi



Edited by citizensc - 05 March 2021 at 1:40am
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