Bass Horn

[Hoerninger]

I have made a simulation for the JBL 4530 based on this plan with the speaker JBL 2226H.
Front chamber 37 l
throat area 505 cm^2
horn length 164 cm
mouth area 3243 cm^2,
combined response of horn and speaker standing on a floor without walls.

For comparison there is a rough frequency response of the 4530 with the speaker 2205 .
____________
Peter

[Dr.db]

Looks like 2~3db gain between 70hz-150hz....!? Right?

[Hoerninger]

For the simulation I have choosen the combined responses from the cone and the horn mouth. The path lenght difference was choosen with 0 cm.
The first picture shows the horn with the original 2205, the second with 2226.

For the first two simulations there is a amazing conformity of the lowest two frequency dips compared the response shown in post 16. The simulation must show deeper cuts as the program does not take care for different path length from the cones back to the horn throat.
Additionaly the simulation shows that the maximum at about 250 Hz is a bit lower than that at 700 - 1000 Hz.
The simulated response above about 350 Hz must be taken with a grain of salt, as the program assumes the cone to behave like a rigid piston. Nevertheless the abrupt fall off at about 700 hz can be seen in the simulation too.

At 46 Hz the simulated response is 6 dB down compared to 70 Hz.

In the third simulation the horn is not assumed to be in a corner (0,5 Pi) but standing free on a floor (2Pi). The differences are obvious.

The data entry field for the 2226H working in a corner is added.
____________
Peter

[Hoerninger]

Same horn with JBL 2226H but front loaded and standing in a corner.
The back chamber is choosen with 55 l.
The volume between cone and throat is reduced from ca 34 l to 3 l.

The grey graph showes the result for 2Pi.
____________
Peter

[Dr.db]

Thanks a lot Peter!!!


I believe the simulations show me I gotta go with the 2226h in a frontloaded horn.
This one does go as deep as the usual scoop but with strong midbass performens in addition

The frontloaded application seems to be capable to run up to 300hz without any issues.





Please excuse me for this silly question;
Do I interpretate the simulation of the frontloaded JBL 2226h right!?
Will it produce 101db @ 50hz with 1watt input at 1meter distance...?



I wish everyone of you an enjoyable weekend!!
All the best,
Olaf

[Hoerninger]

The frontloaded application seems to be capable to run up to 300hz without any issues.

It seems to be, at least the simulation shows it. The mass of the cone is relatively low to support this.

Care for the bends in a folded horn.

A horn is no sausage!

A good horn is straight - or there are reflectors,which reflect(!) the sound to the mouth and not backwards. A curved bend will produce unpredictable cancellations at the higher frequencies.
Dr.Bruce Edgar has made some investigations which are published in Speaker Builder 3/93 p.13.
A legalized copy is at Volvotreters site with "The Monolith Horn, page 2":
http://www.volvotreter.de/dl-section.htm
And Electro Voice patented something regarding reflections in 90 degrees bends.

The California horn has reflectors and they are angled the right way. It delivers far more than 300 Hz with a light cone.

Will it produce 101db @ 50hz with 1watt input at 1meter distance...?

Oh ja! That's the theorie - place another speaker aside and you will experience it . But due to the low distortions the horn will not sound "loud".
I am shure you have read the sound impression regarding the Paragon XXL.
____________
Peter

[hmolwitz]

If you are looking for that last octave outdoors, with modest power, you really need a dedicated sub horn.
Steve Schell built this http://audioheritage.org/vbulletin/s...&highlight=big

Folds and bends are way less critical in a sub horn due to the wavelengths involved.

I built a similar compression loaded sub horn, and found it very effective at producing substantial bass for a modest investment in chipboard. I used a pair of Altec 3156 to drive mine as they were available.
Harry

[originaltubino]

Same horn with JBL 2226H but front loaded and standing in a corner.
The back chamber is choosen with 55 l.
The volume between cone and throat is reduced from ca 34 l to 3 l.

The grey graph showes the result for 2Pi.

This is very very interesting to me. I have a pair of 2226 I'd like to use in a 3-way. I've got tractrix-horn loading from 200-800, and am looking for horn-loading below that. Would you please share the dimensions of the horn to yield that graph? Or if it's easier, perhaps you could share the Hornresp file? I can PM my email address. I'm a total novice with hornresp, but I think I have enough determination to learn what I need from it.

[subwoof]

The JBL front loaded horns do NO benefit below 100Hz...

The rear loaded horns DO.

Size matters and the basics of physics do too.

The length, mouth size and flare cannot be mitigated...

read read read

[Hoerninger]

Would you please share the dimensions of the horn to yield that graph? Or if it's easier, perhaps you could share the Hornresp file?

This horn does not exist. It is a simulation to compare a frontloaded horn with a backloaded horn.
The ideal horn dimensions are those of the 4530 simulation (post #19).
The throat chamber volume Vtc is changed from 34000 cm^3 to 3000 cm^3 with a throat chamber area Atc = 880 cm^2.
The back chamber is choosen with Vrc = 55 liter and a depth of Lrc = 20 cm.
Due to the increased volume this simulated horn will be slightly bigger than the JBL 4530.
Additionally the horn needs a new folding! This is not difficulty but VERY time consuming until all dimensions fit well. And it is completely DIY, there are no experiences so far, it is completely on your own risk.

Btw have you noticed post no.11?

It is easier to build something you can rely on. I can fullheartedly recommend this horn, I have built, tested and stressed it. It works fine. Four of them standing freely on a floor made the helicopters from "Ride of the Valkyre" in the film "Apokalypse Now" more than alive.
The dimensions are in such a way that it is not very neat for a living room in case WAF is of importance. The only restriction for me has been that it fits into the elevator.
____________
Peter

[Hoerninger]

If you are looking for that last octave outdoors, with modest power, you really need a dedicated sub horn.
Steve Schell built this http://audioheritage.org/vbulletin/s...&highlight=big

Folds and bends are way less critical in a sub horn due to the wavelengths involved.

This is quite a different animal!
I have been fascinated by this design and it inspired me to another simulation. Luckily Steve Schell chimed in. He said " ... beginning to fall by 80Hz.", which indicates, that bending has a restrictive influence on the upper limit.

Folds and bends are way less critical in a sub horn due to the wavelengths involved.

Fully accepted. The thread starter Dr.db demanded "from 40hz up to 150hz " at the beginning but now he seems to be taken with 40Hz to 300 Hz.
For 300 Hz you should care for the bends IMHO.
____________
Peter

[Dr.db]

@hmolwitz: Thanks for the link!!


@subwoof: You mean the scoops and original frontloaded JBL`s?
Usually frontloaded horns (like the California) should be able to produce below 100hz... If the hornlengh is bout 2meters... right? Or did I get you wrong?


@Hoerninger: 150hz is enough, I just said it would be able to even handle 300hz.... for those who need that.

[OLDGEN]

i have loaded JBL D130 into my 4520 (http://www.stageaccompany.com/vintag...520s-4495s.pdf)
and bass is terrible, with my tube amplifiers, with SE or PushPull.

[louped garouv]

i have loaded JBL D130 into my 4520 (http://www.stageaccompany.com/vintag...520s-4495s.pdf)
and bass is terrible, with my tube amplifiers, with SE or PushPull.

you should have a very good mid bass though, right?
just missing the lower bass extension?

[OLDGEN]

my measurement is my ear, and now I feel I have enougt bass, low-mid, etc.

anyway tomorrow I will check with my soundgenerator