straight bass horn

[boptura]

hi,

i am considering to start building a pair of bass horns. would be happy to cover from 35-40Hz to around 120-170Hz.

available space is around 3,5mt in lenght and 1,5-1,75mq for mouth area (each horn)

if mouth area is not large enough i can switch to just one mono bass horn, reaching almost 3mq... how important is the stereo perception under the 150Hz ?

i would prefer to use high efficiency vintage alnicos, if possible, anyway which are your suggested drivers ? 12" or 15" ? how many of them ?

thanks to all !!

 

[Helmuth]

try horn response. There are many drivers suitable. fs/Qts=110 (indication)

 

[boptura]

forgot to mention that i need to be low on mouth, as i need space for the midbass and high horns above...i could use 70, maybe 75cm in mouth high (width can go as large as 4,5-5mt.)

so, in order to avoid a horn with parallel top and bottom sides, i need to be more low on throat, around 50-60 cm, and have a minimum degree of vertical expansion...

i was thinking to use a pair of 12'', one above other ...

another way could be to mount a 15'' on each side, like in the skramstad horn...

which work better ?

tnx

 

[Helmuth]

The bigger the mouth off the horn the higher the cut off frequency. Or the horn will become enormous in total volume.

 

[Helmuth]

Try this one 18"
mivoc awx18

An externally hosted image should be here but it was not working when we last tested it.

awx

 

[boptura]

Helmuth, at now i would prefer remain into 12'' - 15'' range, two drivers, if possible...

attached is my first attempt to calculate the horn, i used Melhuish hypex calculator:

throat area: 600 cm2
flare frequency: 35 Hz
size factor: 2 (horn will be on the floor)
M: 0.8

width: 500 cm
height: 77 cm
lenght: 342 cm

i would prefer vintage drivers, like Altec 414, EV12M, Jensen A12.... or 15'' Altec 515, Jbl 2220, Gauss, Coral..... something better ?


tnx

 

[Helmuth]

Why 12 OR 15"? What is your reason for that.

When you reduce the horn troth will flatten the response and reduce the dimensions

 

[MaVo]

Despite it not being vintage... try Hornresp to simulate your horn speakers. You will be amazed what one can do wrong with horns if some paramters are not right. Either simulate the horn or build several ones and measure each iteration, until you find the right parameter configuration.

 

[tinitus]

This way of doing it is quite nice

 

[GM]

Yeah, given the height/XO limits, a truncated dual 15"/channel stereo version of this at minimum would be my choice, though four 15"/ channel to further shorten it and limiting the XO point to <150 Hz would be my preference.

GM

 

[Helmuth]

Response of a awx 184 34HZ

 

[Helmuth]

horn

An externally hosted image should be here but it was not working when we last tested it.

 

[Helmuth]

This way of doing it is quite nice

What a great solution

 

[boptura]

i will prefer to use two 12'' or two 15'' drivers, in place to a single 18'' simply because i want continue to use the single horn as a stereo device... yes, i still hear in mono, but it's just for simplicity to not mixing L+R channels into a single speaker.... stupid idea ?

anyway i think i need to learn to use hornresp




tnx

 

[Helmuth]

anyway i think i need to learn to use hornresp

Now I understand why you don't understand my super tip.

When you learn how to use horn response, and after a half year designing horns with all kinds of drivers. You understand how super the awx184 is.

Till than Boptura.

 

[Skramstad]

Totally agree, start learn hornresp

I did some simulations with dual 12", 15" and 18" drivers for a mono bass horn since that probably is the best choice for you.
Then I could see why Helmuth went for the 18"
The dual 18" drivers got lower in frequency than the other drivers had better phase response and more SPL. The frequency response of the dual 18" was pretty flat even in my two minute pre design and had no increase in SPL above 100Hz which could be a critical parameter for you considering use of processing.

The driver I would recommend is the PHL Audio 7321Nd, the cone is a triple sandwich construction which will not break up like the paper cones do. Compared to paper cones the PHL cones have extremely low harmonic distortion even at large cone movements, this means in real life that your simulation will look similar to the measuring you do when the horn is finished If you chose to use two of these drivers your horn will take 2600W continuous down to 30Hz without mechanical damage and play pretty loud (see attached pic) even in half space condition.
You will not find this driver on the PHL site yet, but it is already for sale (have them myself), so ask your dealer.

When a horn is capable of such high SPL it will be a good idea to side mount the drivers so they fire against each other. Side walls should also be coupled together inside the horn with heavy bracing so vibrations in the construction will be at a minimum. For most listeners a mono horn will work properly below 150Hz without loss of listening quality, for experienced listeners 90Hz 24dB low pass filter is the highest crossover I would recommend.