It's been decades since I've done a club build so can't offer a knowledgeable opinion on that aspect. The main challenge of using a combined stage/bass horn is structural vibration. Your thought of using the centre non-horn portion of the stage sounds on the right track. It provides the opportunity to hard tie the desk/equipment platform to the presumably concrete floor beneath the stage and physically separate that structure from the speaker with a small air gap (a fraction of an inch might be enough) to avoid direct structural vibrations from the bass horns.
Otherwise the typical club install techniques - high pass filtering the DJ mic and floating tables - may be enough. Back in the vinyl days turntables sat on large concrete blocks suspended from rubber bands but that was long ago.
@tizman I didn't spot you had other drivers on hand. The Eminence 18245A model looks like the best option you have at the moment. Do you have any images of the driver? for horn application you generally want a strong cone to avoid distortion due to the additional air mass distorting the cone or ultimately at high power just folding the cone. Yes I agree with GM the Qts is sufficient for the design bandwidth but I would also try and have the sub extend (ideally) to twice the crossover frequency to simplify the crossover and avoid issues in the time domain. This is a good paper on low frequency horn design you can plug T/S parameters into to get performance expectations: https://www.xlrtechs.com/dbkeele.co...Preprint) - LF Horn Design Using TS Paras.pdf
For isolating the DJ table I find putting rubber blocks under the legs, using a very solid and heavy table made of stage deck material and steel, double layers of paving slabs with rubber isolation between them and iso feet on the actual turntable (1210 MK2) is able to tame even a violently bucking stage. However it's a bit weird to try and DJ with massive amounts of vibration coming through your feet.
This sounds like a great project but will it be worth it, would it be a lot simpler to run an array of large dia sealed subs like Stereo Integrity HS24" in 10Cf boxes?
Here are a couple of the driver, snd one of the sub it was used in. The sub was sealed and good for 20 HZ. The Energy ES-18XL.
Good read for BP bassheads like myself. However, if we followed that paper, then basically, no car audio driver would never be placed in a BP4 or BP6 type enclosure.
The goal is primarily sound quality. The main system will be horn speakers, so I thought it might be a better match. While building it may be a PITA, wouldn’t building a bunch of sealed boxes be one as well? How many boxes would I need to equal the output of two bass horns of the proposed size? Assuming equal FR and output performance, what would sound better? To be honest, I have made a few assumptions that may be very well be incorrect.
IMHO,
1ST .Define your target SPL at the listening position
Then take your horn design and with their output specs calculate how many horns and power you need to hit your target SPL at the listening position.
Then take one or 2 BR designs and with their output specs see how many you need to hit the same target SPL.
Then calculate cost for the 2 solutions (drivers,wood,man hours to assemble)
With that you will know what route to take, horns are a PITA to build compared to BR, but in the other hand they are more efficient so at least in theory you will need less cabinets than BR.
So it is a juggling act, depending what you need/want.
One point in favour of BR is that being modular so you will use lets say 6 or 8 cabs.
If one or 2 go down people will not notice much or not at all.
With your pair of horns if one blew, it will be around 6db less so it will be very noticeable.
But at the end is what you decide to do,
Every solution have their own pros and cons.
My 2 cents.
Max.
1ST .Define your target SPL at the listening position
Then take your horn design and with their output specs calculate how many horns and power you need to hit your target SPL at the listening position.
Then take one or 2 BR designs and with their output specs see how many you need to hit the same target SPL.
Then calculate cost for the 2 solutions (drivers,wood,man hours to assemble)
With that you will know what route to take, horns are a PITA to build compared to BR, but in the other hand they are more efficient so at least in theory you will need less cabinets than BR.
So it is a juggling act, depending what you need/want.
One point in favour of BR is that being modular so you will use lets say 6 or 8 cabs.
If one or 2 go down people will not notice much or not at all.
With your pair of horns if one blew, it will be around 6db less so it will be very noticeable.
But at the end is what you decide to do,
Every solution have their own pros and cons.
My 2 cents.
Max.
kipman725: Do you think the 18" driver looks appropriate based on the photos and its original use?
some aspects of it worry me:
1) was used in sealed sub with low frequency extension so probably quite low motor force, high excursion driver
2) foam surround
3) strength of cone?
4) restorative force from suspension could be low
Measure the T/S parameters and we can simulate it though. https://www.roomeqwizard.com/help/help_en-GB/html/impedancemeasurement.html
1) was used in sealed sub with low frequency extension so probably quite low motor force, high excursion driver
2) foam surround
3) strength of cone?
4) restorative force from suspension could be low
Measure the T/S parameters and we can simulate it though. https://www.roomeqwizard.com/help/help_en-GB/html/impedancemeasurement.html
Your 30 inch height limits you to a 18 or 21 inch driver. You have the room to build horns (but complex to build correctly) and you have to be able to access the driver for service. It’s also enough room to build reflex boxes and use multiple drivers.
Multiple Back loaded horns like the Jbl 4530 work well, but you won’t get 20 hz .
I had your problem but had enough stage height to get a pair of Berthas under the stage with 2 mono blocked Crest 8001s driving them. I was also lucky enough to work with Richard Long on a couple of clubs.
Multiple Back loaded horns like the Jbl 4530 work well, but you won’t get 20 hz .
I had your problem but had enough stage height to get a pair of Berthas under the stage with 2 mono blocked Crest 8001s driving them. I was also lucky enough to work with Richard Long on a couple of clubs.
Last edited:
Richard Long had a half height single 18 version of the Bertha called the Emerald. That would be ideal if you can find the plans or use the design software
weirdly I have experience of the emeralds and berthas (with extensions), some people have plans but they won't share. The Emeralds need to be stacked to have sufficient mouth size and then without extensions are only really a 40Hz box, the amplifier was not massivly powerful for the Emeralds so I don't have an idea of maximum SPL. I didn't measure the extended berthas but the bass was.... sufficient for all possible indoor requirements.
I did a club with Richard where we double stacked 2 sets of very rare Berthas with 10 foot mouths one on top of the other rather than the normal 8 foot wide mouth - resulting in more than twice the mouth area of a typical Bertha. I don’t think anyone else ever did that.
it went low and had some wonderful dynamics…..
it went low and had some wonderful dynamics…..
This is what i can find on the web supposedly is a Bertha cab.
if someone can translate the plan dimensions in to hornresp and simulate to verify the plans are ok.
( is a W bin ? )
if someone can translate the plan dimensions in to hornresp and simulate to verify the plans are ok.
( is a W bin ? )
There is some mouth extension talk here
https://forum.speakerplans.com/levan-horn-extension_topic58957_page1.html
and some back chamber mod here
https://www.diyaudio.com/community/threads/big-bertha.232565/
https://forum.speakerplans.com/levan-horn-extension_topic58957_page1.html
and some back chamber mod here
https://www.diyaudio.com/community/threads/big-bertha.232565/
so there is nothing new under the sun about W bins
but as i read people who built/installed berthas loved them, i guess cause the sonic signature of that particular horn ?
at the time the drivers were very low power capable
so what happen if somebody stuff a bertha with a pair of IPALS or 18SW115's and drive them at max capability 8kw each driver ?
4 berthas for a total of 8 drivers with the proper amplification YUMMM!!!.
most of the clubs that had them, used 4, one on each corner firing to the dance floor, people feel their guts shake
and i think some ones stacked a pair on each corner!!
B&C's DS115' @Full blast NUCLEAR NUKE!!!
.
but as i read people who built/installed berthas loved them, i guess cause the sonic signature of that particular horn ?
at the time the drivers were very low power capable
so what happen if somebody stuff a bertha with a pair of IPALS or 18SW115's and drive them at max capability 8kw each driver ?
4 berthas for a total of 8 drivers with the proper amplification YUMMM!!!.
most of the clubs that had them, used 4, one on each corner firing to the dance floor, people feel their guts shake
and i think some ones stacked a pair on each corner!!
B&C's DS115' @Full blast NUCLEAR NUKE!!!
.
Last edited: