Critical Midhorn Build

[lbstyling]

Hi,
I wish to build a horn speaker with the following design perameters-

Idealy a horn mid that covers the critical mid range, say around 400 to 2.5k or higher.
This horn would be idealy 18" wide (a bit more is acceptable) and have a roundover exit. The horn will also need to be a classic round shape, and have a uniform flat finish that can be painted in a gloss finish.
Foam inserts would be used to reduce potential for 'honk/ HOM)- Minimum 'honk' noise is a important factor for me.
The majority of the fund could be spent on this section.


The bass section would idealy comprise of drivers no larger than 10" and could use fairly cheap drivers.


The trebble would also be a horn design and should match the form of the mid horn.


System max spl in the region of 115db+ if possible, as these will be used for surround sound regularly.
Passive crossovers are a must.

My taste typically leans towards a slightly bright voicing if that helps.

The inspiration is the advantgarde trio/duo Avantgarde Acoustic

The budget is approx £1500 for a pair.

Any and all advice or help on this mamoth project is hugely appreciated

[lbstyling]

Ist things first-
The mid horn and driver-
This is one possible option-

1.0" Stereo Lab cf250 Hz Spheric Wave Tractrix Horn - STEREO LAB

They are in europe so delivery is possible. -the problem being that they are expensive and they dont have a roundover lip.

I idealy would like one of the jzagaja horns from the group buy jzagaja has on here, but it applys to the US and Im in the UK.
I would love a JMLC OR OSWG 18" horn with a roundover exit or even without+ I just make a roundover attachment, but I dont know if I can get it, as im not in the US.

question 2-
Will I need a 2" compression driver to get the required frequency range and the spl capability?

[lbstyling]

Ok,
So an update,

It looks likely I will go with a 18" JMLC horn from jzagaja on the 'waveguides and horns' group buy thread on this forum.

The question now is what compression driver and what sise.?

[lbstyling]

Update-

Im stuck between using a 350hz 1.4" entry horn and the 2" one.

the 2" driver I would use would likely be this
http://www.radianaudio.com/component...60pb_850pb.pdf

The 850pb would be the best, and can be bought second hand fairly cheap.
The drawback to this is that its only going to be flat up to 10khz because of the horn- so will need a supertweeter on top. (-No idea what at this point)
The added cost isnt overly welcome, but I much prefer the aesthetics of having a small horn on top for this.

or 1.4" exit with a beyma 755ti or equivelent attached and no tweeter.- much cheaper, and simpler, but I realy like the look of a small horn on top.

Can anyone give me any advice on this?

bass/mid could be 2 AE 10" drivers 10x??

[SunRa]

Hello, I have a comment regarding the bass/mid. Seeing a 18" waveguide near 10" just doesn;t seem right... Only if you use many of them..

[pedroskova]

Agree with Sun Ra. If your horn/wave guide can be loaded down to ~500Hz, you might as well take advantage of this and use a 15" bass/low mid, both for better performance and aesthetics.

[ScottG]

Originally Posted by lbstyling

Ok,
So an update,

It looks likely I will go with a 18" JMLC horn from jzagaja on the 'waveguides and horns' group buy thread on this forum.

The question now is what compression driver and what sise.?

The horn loading has more to do with extension than the driver itself, particularly with a "soft" suspension driver. Hard (integrated) suspensions have substantially increased THD levels below resonance and aren't as useful in this application.

Diffraction can be lowered at the mouth via acoustic suppression in the form of a support frame that absorbs the diffraction from the horn mouth. (..this does NOT reference filling the horn with foam as the Gedlee products do.) This allows you to user a smaller diameter horn because the absence of need for a large round-over mouth exit.

The upper freq. response, especially in relation to dispersion and overall linearity, is largely dependent on the diameter of the compression driver. So to is the resulting size of the horn for a given lower freq. operation point. (..smaller means wider high freq. dispersion (horn dependent), extended linearity, and a smaller horn for a given lower freq. "cut-off".)

Combine all of this and the Stereolab you have provided a link to is probably your best bet with a 1" compression driver that has complaint surround (..like mylar). Then support the mouth of the horn via a stand that has various density foams/insulation to absorb the diffraction from the horn. The Radian 475PB would likely perform well (..not only having a compliant surround but also has a relatively low resonance when compared to other full-bandwidth 1" exit drivers).

This doesn't invalidate the JMMLC horns (which are likely better *built*).. BUT they will be larger for an equal operating low freq. bandwidth. On the other hand a diffraction suppression/absorption system would be less important.



Suggestion: Go listen to a system like this before you continue on with your project. Similar restraints usually result in a system that is *quite* directional (where you are using just one horn and one driver), and subjectively this is likely to be either something you like, or something you hate.


Caution: A multi-horn system is also possible, BUT you are talking about some thing much larger AND it would require *very* careful crossover work and horn/driver integration. You could of course use the system presented as a mid only, but again, you'll have issues with integration.




BTW, assuming you stick with your current plan of mid-horn and 1.4" exit drivers this is a good one:
http://www.eighteensound.com/index.a...roduct&pid=253

[TrueSound]

The Radian 850 will not be usable in a 350 Hz horn below around 800 Hz. You should find a more suitable driver like a 4" with a phenolic diaphragm like the JBL 2285 if you want to go down to 500. You should also look for a much larger horn if you expect good response to 400.

[Jmmlc]

Hello lbstyling,

The group buy is intended to limit the cost of the postage to US from Europ.

But if you contact Jack Zagaja I think there is no problem for you to order from UK apart the group buy.

Best regards from Paris, France

Jean-Michel Le Cléac'h

Originally Posted by lbstyling

I idealy would like one of the jzagaja horns from the group buy jzagaja has on here, but it applys to the US and Im in the UK.

[djn]

Originally Posted by lbstyling

Ist things first-
The mid horn and driver-
This is one possible option-

1.0" Stereo Lab cf250 Hz Spheric Wave Tractrix Horn - STEREO LAB

They are in europe so delivery is possible. -the problem being that they are expensive and they dont have a roundover lip.

I idealy would like one of the jzagaja horns from the group buy jzagaja has on here, but it applys to the US and Im in the UK.
I would love a JMLC OR OSWG 18" horn with a roundover exit or even without+ I just make a roundover attachment, but I dont know if I can get it, as im not in the US.

question 2-
Will I need a 2" compression driver to get the required frequency range and the spl capability?

I use the Stereo Lab 400hz 2" tractrix horn. It sounds great and is VERY well built. It is a great deal for the price.