Tractrix horn question

[lamia1]

I'm just getting started so pardon me if this is a dumb question, but are all 150hz tractrix horns w/a 2"opening the same or are there other concerns affected the type of compression driver chosen?

 

[GM]

They should be, though they aren't necessarily optimum for every 2" exit driver. IOW, ideally you want the horn's initial flare angle to match the driver's, but there's another consideration with the Tractrix flare in that it's very slow expanding initially, so to match these to a narrow angle exit such as the various Altec 200 series models have would require a much larger, longer horn than a wider ('faster') exit which will beam excessively for some.

GM

 

[lamia1]

Tons more questions

GM, I see you are really local, I'm in Johns creek right off state br. Rd. Because I'm new, I can't pm you yet, but would love to pick your brain, possibly hear each other's set ups (I currently have Avantgarde Duo's), etc. If interested, you could pm me how to contact. Thanks-Phil

 

[GM]

Gees...... I didn't even notice, but then I'm just reading/posting between commercials, cautions. Anyway, YGM.

GM

 

[John Sheerin]

In theory, the part of the flair described by the tractrix equation should be the same. That goes from the throat to where the horn has flaired out to 90 degrees from its axis. The differences will then show up in what happens past there. Most people use a somewhat sharp edge. This is bad. It is better to use a radius that is as big as the flair at the mouth of the horn or something similar. Le Cleac'h horns do this but a lot of people cut off the roll back from the mouth early to save space (which is not good).

 

[revintage]

The throat of the 2" JBLs has a exponential flare in the ballpark of 180Hz.

As tractrix and exp are close to identical at the throat it could be a good idea to choose this frequency for the horn.

If doing so an initial area of 11,64cm2 should be chosen and 69mm(drivers part) substracted from the total length.