Need advice on a horn based system

GestaltH

Member
2008-01-21 6:44 pm
Hi,

I'm new to the whole DIY audio thing. As a first project, I want to make a system based on horns. It primary use will be home theater, but I want it to sound good with music too. I'm on a budget, but I want it to be a significant upgrade from my current system which is a creative Gigaworks S750. This shouldn't be too hard as its only a $400 commercial system.

What I'm looking at so far:

Subwoofer (20-150 Hz): Tuba Home Theater http://www.billfitzmaurice.com/THT.html

Mid bass (150-2500 Hz): ?? I need advice on this

Tweeter (2500 - 20000 HZ): BMS 4540nd compression driver with a parts express 12" waveguide. I'll buy a couple of cheap waveguides/horns from parts express to try out at the same time. If I don't like any of them, then I'll upgrade to something more expensive (maybe from 18 sound).

I need advice on what to do with the mid bass. It would make sense for it to have a sensitivity of about 100-105 db to match up with the sub and tweeter. I want it to sound natural and it also needs to be fairly cheep. Also, what do you think about the components that I have already chosen?

Also, I guess I should mention that I'm planning to bi-amp the speakers with low component chip amps. I'm planning to start out building a 2.1 system, and if I like the results, I'll upgrade to 7.2. Space to put the speakers is not a big deal to me. 50% speaker area and 50% living area is fine by me. However, I would like the speakers to be smaller than the 3x3x3 ft subwoofer.

Thanks,
GestaltH
 
GestaltH said:


I need advice on what to do with the mid bass. It would make sense for it to have a sensitivity of about 100-105 db to match up with the sub and tweeter. I want it to sound natural and it also needs to be fairly cheep.


B&C 10HPL64 10" (+/-)98dB Neodymium Woofer ($119.93)
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=294-678

Selenium 10PW3-SLF 10" Driver (+/-)94dB ($48.00) with stamped steel frame though.
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=264-332

Eminence DELTALITE®-II 2515 (+/-)99dB 15" though, to xover/connect to a CD.
http://www.eminence.com/proaudio_sp...DELTALITE-II2515&speaker_size=15&SUB_CAT_ID=3

To make it louder you need a horn on the midbass or an expensive driver not a cheep one.
 
Hi,
you are asking the mid horn to cover 4octaves.
This is the speaker that will handle most of the information and 4octaves might be asking a bit much from a high quality horn.
I guess a driver around 4inch to 6inch would couple to a Tractrix quite well. But it must have a strong magnet and a high BL to drive the horn properly. If you want 150 to 2500Hz from this driver than look for drivers that are distortion free from 70 to 5000Hz. That will be a tall order.
But, I'm sure some here can give you possible candidates.
There is another thread discussing mid drivers. Have a look for it.
 
It is nearly impossible to cover 150 to 2.5K with that sensitivity unless you use multiple drivers - then you will have problems with driver spacing unless you limit the bandwidth of one of the drivers. A horn to cover that wide of range will be large, and will place the treble driver too far from it's center and will be compromised in bandwidth and difficult to build to cover that wide of range. think using a compression driver that can be crossed over below 1200 cycles is a better way to go. IOW use a compression driver / horn that will go much lower. It will much eaiser to get good results,
 
Magnetar said:
think using a compression driver that can be crossed over below 1200 cycles is a better way to go. IOW use a compression driver / horn that will go much lower. It will much eaiser to get good results,

Hi Magnetar,
I think that's a good idea (for a start) for a pair woofer cone/compression driver on the lower xover band close to 1K2 for the BMS CD and a 3.order network on its side and about 10dB+ attenuation.
 
Inductor said:


Hi Magnetar,
I think that's a good idea (for a start) for a pair woofer cone/compression driver on the lower xover band close to 1K2 for the BMS CD and a 3.order network on its side and about 10dB+ attenuation.

I agree but am not too sure about the driver he already has using it that low. I had a pair and thought they were best used as a tweeter above 4k. It seemed strained and hard sounding (odd order distortion?) when used any lower then that

I like the little Beyma CP380 in a small format driver for that bandwith
 
Magnetar said:

I agree but am not too sure about the driver he already has using it that low.

Recomended xover @1900Hz for the BMS CD.
Another idea for the woofer is a BMS ($200.00+/100dB+).
 

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Horn suggestions--mid bass

While I cannot comment on your choice of either the sub or the BMS drivers, I would suggest you carefully look at the JBL 2206 12" for the mid bass. It is flat, low distortion, high output, etc. Available for the bargain price of around $275-300 each.

IMHO this is the most important component of your new speaker system.

Good luck.
 
Re: Horn suggestions--mid bass

homebuilder said:
While I cannot comment on your choice of either the sub or the BMS drivers, I would suggest you carefully look at the JBL 2206 12" for the mid bass. It is flat, low distortion, high output, etc. Available for the bargain price of around $275-300 each.

IMHO this is the most important component of your new speaker system.

Good luck.

Yes, homebuilder. And thinking about saving money I guess it would work well without a crossover for the JBL. No doubt the best driver around. Make it two...

This baby is ruler flat from 150Hz to 2000Hz @112dB with no distortion in sight. Tell me about building pro speakers.
 

GestaltH

Member
2008-01-21 6:44 pm
Re: Re: Horn suggestions--mid bass

Thanks for all the great suggestions.

One possible route is to go to a 3 way system: (80 to 100)-500 Hz, 500-4000 Hz, and 4000-20000 Hz. This is not very cost effective though since I will need to build an extra horn and amp such. I guess I'll count this one out of the running.

I could also try crossing over the 4540ND driver lower at 1200-1900 Hz and using a driver thats good from 50-4000 Hz such as the B&C 12" Neo but only use it for 150-(1200 to 1900) Hz. This is fairly cost effective, but would it sound good? This is about $240 in drivers per speaker.

The next step up would be to use the CP380/M instead of 4540ND for the high end and cross it over at like 1200 Hz. That would be about $310 in drivers.

The best solution seems to be to use the JBL 2206 from 125-2000 Hz and then use the Beyma CP380/M from 2000-20000 Hz. I don't know if I can afford this though. This is about $470 in drivers per speaker.

I was looking at the Celestion NTR12-3018D as a possible alternative the the JBL since it seems to be fairly flat from 100-2000 Hz also. I can't find any info on where to buy it or how much it costs though. Anyone have any experience with these?

Also, just a general question. What is the formula for a Tractrix horn? Also, what is the difference between a hyperbolic exponential and a normal exponential? Is there a good website that lays out the different horn geometries somewhere? I'm thinking about building my own high frequency horn instead of buying cheap ones from parts express.

Inductor said:


B&C 10HPL64 10" (+/-)98dB Neodymium Woofer ($119.93)
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=294-678

Selenium 10PW3-SLF 10" Driver (+/-)94dB ($48.00) with stamped steel frame though.
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=264-332

Eminence DELTALITE®-II 2515 (+/-)99dB 15" though, to xover/connect to a CD.
http://www.eminence.com/proaudio_sp...DELTALITE-II2515&speaker_size=15&SUB_CAT_ID=3

Thanks for the suggestions. I also kind of liked the B&C 8" Neo driver.

AndrewT said:
Hi,
you are asking the mid horn to cover 4octaves.
This is the speaker that will handle most of the information and 4octaves might be asking a bit much from a high quality horn.

Yea, I guess that is a bit much. I'm pretty new to this type of thing. Do horns have a upper cutoff frequency? HornResp seems to show that they do, but what factors effect it?

Magnetar said:

I like the little Beyma CP380 in a small format driver for that bandwith

I didn't notice the CP380 when I was looking for drivers. It looks like a really good driver, although a bit more money than the 4540ND. It should sound ok at 1200 Hz though?

homebuilder said:
I would suggest you carefully look at the JBL 2206 12" for the mid bass. It is flat, low distortion, high output, etc. Available for the bargain price of around $275-300 each.

IMHO this is the most important component of your new speaker system.

Good luck.

This looks like a very good driver. I think that it might be over my budget though. Do you know of any other drivers that are almost as good but a little less money? I'll definitely keep an eye out for a good deal on these though. Maybe I'll be able to pick some up.
 

Don Bunce

Member
2007-03-21 3:55 pm
The Single Driver website has a calculator to design your horns.

http://melhuish.org/audio/software.html

For a Tractrix,you will need to multiply your low cutoff freq by about .7 to determine the flare of the horn.For example,if you want 150 hz,you will need to make a 105 hz horn.

For a mid-bass horn,I would suggest using the front horn section from the Altec 825/828 cabinet.It is a 110Hz 1/2 space expo horn.Make a back chamber of about 1 cu ft.Works well with the Altec 416 or better still,(IMO)JBL 2205a.Haven't tried any other drivers,but I'm sure there are plenty of 15" drivers that would work also.

Prices on the Altec A7's has gone up a lot in the last few years,but you might be able to find a beat up set of cabinets for a reasonable price.I think it would be about as easy to just build them from scratch as to modify an existing pair.They will wind up being 30" h x22" w x 24" d

Plans are available on the web,just Google.
 

GestaltH

Member
2008-01-21 6:44 pm
Re: Horn suggestions--mid bass

I can't get the JBL 2206H driver to respond well up to even 1200 Hz in HornResp. I've attached the SPL graph of the best that I could get. Am I doing something wrong, or is this just not a very good driver for a horn?

It seems to me that the drivers with a low Le seem to model higher frequencies better in HornResp.
 

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GestaltH

Member
2008-01-21 6:44 pm
MikeHunt79 said:
I wonder what driver is used in this design?

http://www.billfitzmaurice.com/DR200.html

After looking at the THT, the DR200 seems to do 150Hz up quite nicely.... I imagine it's crossedover at around 2k or 3k?

I'm not saying build a DR200, but you may be able to do something similar, sans tweeters and pass XO. :)


Hmmm. Interesting. They are selling kits for the DR200 on this site: http://www.speakerhardware.com/proddetail.asp?prod=DR200kit

I'm guessing that the driver that they are referring to is the Eminence Beta 8A:
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=290-404

I was able to model this one in HornResp a lot better. I can actually get from 150-1500Hz with it. I've attached a graph. Are the wiggles on the low end normal?
 

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JBL 2206 Midbass

I would ask why build the horn? The 2206 can easily be eq'd if needed to gain a bit more bottom end. Can the horn extend the upper end?

Take a look at your total costs:

The 2206 only needs a 1.0 to 1.2 cf net enclosure. (cheap)
The 2226 15"would cost less than horns for more bottom end.
They can both be found on eBAY

If the woodworking is part of the enjoyment to you, then by all means go for it. In my project, I ended up staying away from horns, and going with the straight driver. We are doing projects for both the 2206, and the TAD 1201H.

Good luck!
 

GestaltH

Member
2008-01-21 6:44 pm
Re: JBL 2206 Midbass

homebuilder said:
I would ask why build the horn? The 2206 can easily be eq'd if needed to gain a bit more bottom end. Can the horn extend the upper end?

I'm really set on at least trying the horn thing. I might later decide to do a direct radiator system. Also, a friend of mine might be doing a speaker system at the same time, so I'll pass along the info. I did notice that JBL has the 2012H 10" driver that is intended for horn use. That one modeled very well. It has an inductance of 0 at 1kHz. Its $250 though and I can't find that one used.
 

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