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Calling all horn theorists! RLH questions

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budney View Drop Down
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    Posted: 09 April 2018 at 7:51pm
Im curious as to how having the drivers at one end of the cab, with one large horn, would differ from having the drivers in the middle, with 2 smaller horns either side. The examples I've chosen are the Jensen Imperial (but with 2 drivers) and the Hill M4. For arguments sake, lets assume they have the same horn path and same drivers. I chose these for examples because they are the closest commercial designs I've been able to find to the RLA boxes that I'm interested in. Lets also assume that there's no labyrinth or fold in these horns, and keep the horn path simple like the Jensen. I admit that I'm not too versed on speaker design, I have researched quite a bit of horn theory but I don't know enough to apply it to my question. I am asking to learn from someone who already knows a bit about this. 

Also for people who would tell me to not bother using these old designs and use something modern, I'm not interested Smile this is purely something I'm curious about and I can't figure it out on my own. I would be tempted to build one of each, Waldorf and Ultima, but I cannot find plans anywhere so want to become a bit more informed before I start experimenting and prototyping. 

some examples

the Jensen Imperial

Hill M4 (these are with 12 inch drivers, I've not been able to find a design like this that uses 15)


The two RLA boxes

The Waldorf 

The Ultima



TLDR: what would be the benefit of having drivers in the middle as opposed to one end of the cab if all other variables are kept the same, and when would you use one and not the other?


Edited by budney - 09 April 2018 at 7:52pm
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Hemisphere View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Hemisphere Quote  Post ReplyReply Direct Link To This Post Posted: 09 April 2018 at 8:09pm
Practically no difference to having the drivers centered or at the sides. The bass frequencies being reproduced by these designs just don't care for such trivial distances.

Where you would encounter a problem, however, is in those more esoteric DIY designs, home theatre ie, where the same driver that plays bass through a horn is also being asked to play the mids and sometimes the entire range, through it's direct radiating element. In those cases you absolutely need to have the drivers centred (or all on the same side).

Barely counts for mids to be honest though, it's really a treble issue - you can calculate it based on distance between drivers vs the length of the wave. And you don't 'absolutely' need them centred even for treble you just get comb filtering effects if you don't. Doesn't seem to bother classic reggae systems!


Edited by Hemisphere - 09 April 2018 at 10:20pm
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toastyghost View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote toastyghost Quote  Post ReplyReply Direct Link To This Post Posted: 09 April 2018 at 10:56pm
Both of the horns you want to emulate were midrange / upper bass devices rather than subs
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Post Options Post Options   Thanks (0) Thanks(0)   Quote budney Quote  Post ReplyReply Direct Link To This Post Posted: 09 April 2018 at 11:39pm
Originally posted by Hemisphere Hemisphere wrote:

Practically no difference to having the drivers centered or at the sides. The bass frequencies being reproduced by these designs just don't care for such trivial distances.

I guess the question then becomes, why use one and not the other, if they are both the same? Surely there must be an application for one to be better than the other? The only reason I can think is for if you want to have a large stack, i.e 4 drivers for mid bass, instead of 2, then you would use the driver in the middle purely for the stack aesthetic? I'd be running them up to aprox 700hz where the lens would take over, so they'll be for bass duties only. 

Another reason could be to be able to 'extend' the mid bass, like these stacks. Cool design, never seen any other like it, the extension on the mid bass matches the extension that can be done to the W Bertha sub, I would love to hear this! I've asked the guys who built it for some info but they're keeping it secret Unhappy I guess it would increase the efficiency of the horn for the mid bass? 




Originally posted by toastyghost toastyghost wrote:

Both of the horns you want to emulate were midrange / upper bass devices rather than subs

I had planned on running them on top of a single 18 Bertha, an 'Emerald' like the pics above, or maybe something modern like a Lab or Danley, haven't made my mind up. I'd probably run mid bass down to about 60hz, then use the sub as an effect from the crossover I have, but I need to experiment first and I haven't got to that stage yet


Edited by budney - 09 April 2018 at 11:41pm
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prev.ious View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote prev.ious Quote  Post ReplyReply Direct Link To This Post Posted: 12 February 2020 at 4:17am
Yes man, interesting thread, I was also very curious for this build you showed pictures of. 

Do you know where i can find plans for the Bertha/Levan?
My main question however is: would the Berta/Levan with freq response of 20-100hz be a suitable match with some altec 817 low mid range cabinet which cover 100-800hz? 
Thanks in advance
matt
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