Theoretical TS question regarding horn drivers

[SpeakerBob]

Hi All,

I'm currently running an EVM15L driver on a front loaded horn. I've been toying with swapping to a pair of 10's instead. If I had a list of TS specs in front of me which ones would change between the 10 and the 15 ? I know SD, xmax possibly, but am not sure of the rest.

Basically I'm trying to source a pair of 10's that have a combined TS spec equal to the EVM15L on the same horn.

Thanks,
Rob.

 

[AllenB]

It would be good to model this using hornresp.exe Not only will you see whether the other driver is suitable for the horn, but also efficiency, maximum output per frequency and many other properties.

 

[SpeakerBob]

Thanks Allen,

The question was more about choosing the drivers before modelling (I have the horn modelled in hornresp already.)

If the 2 tens were to match the EV's TS parameters, which TS parameters would be different ? (would the 10's need a BL figure half of the EV's figure for example )

Rob.

 

[GM]

The two 10" summed ideally needs to have the EV's specs except 1/2 the Vas, Re [or 2x if parallel wired].

 

[SpeakerBob]

Thanks GM !

 

[David McBean]

The question was more about choosing the drivers before modelling (I have the horn modelled in hornresp already.)

If you already have the system modelled with the EVM15L driver, the 'Multiple Driver Equivalent' option in the Loudspeaker Configuration tool can be used to find the required parameter values for multiple drivers.

 

[SpeakerBob]

Brilliant!, Thanks David.

Rob.

 

[GM]

Thanks GM !

You're welcome, though forgot to mention to halve or double the Le also. 🙁

 

[SpeakerBob]

No worries, I'll start looking for drivers over the next few weeks.

Thanks,
Rob.

 

[weltersys]

If the 2 tens were to match the EV's TS parameters, which TS parameters would be different ?

Rob,

I used EV15L for bass, EV12L, for low mid in a four way system built in 1979, the response in the attached screen print below.

A curvilinear cone like the EV 15L ("Lead Guitar") designed for extended high frequency response does not behave like the flat rigid piston that Hornresp models. At higher pressures (power), the cone tends to "fold", reducing low frequency output compared to the upper response.

Depending on the frequency range you plan to use the drivers, the difference in cone design independent of TS parameters can make quite a difference.

Art

 

[SpeakerBob]

Thanks Art,

I'm currently using my midbass horns from 80Hz to 280Hz with 4th order slopes and want to use the replacements in a similar way. I'm thinking they should be in the pistonic range crossing over that low ?

Funnily enough the 12L's you mentioned are a really close match to what I need 😀

Rob.

 

[GM]

Correct, ideal cone drivers are pistonic up to the VC diameter, so for typical 3" = ~13543/pi/3 = ~1437 Hz if sufficiently rigid/damped, but as Art explained, the reality is that flex is often built-in to flatten/widen its response both on and off axis. Look to the JBL 2225 for the quintessential pistonic horn driver.

 

[weltersys]

Funnily enough the 12L's you mentioned are a really close match to what I need 😀

Rob,

80Hz to 280Hz is not a difficult range to cover, though the EV15L will start to "mush out" probably even before reaching it's 3.3mm Xmax. A stiffer cone with greater Xmax could provide far more clean output, given more power. A pair of 12L would have more Sd than a single 15L, but still have little Xmax and a relatively weak cone, plenty of modern 15" that could easily do provide 6dB or more output.

You probably would not be looking for an alternative to the EV15L if it were what you "need", what are you looking for that it does not provide?

Art

 

[SpeakerBob]

Hi Art,

This is for home use, so maximum output is not an issue.

What I'm trying to do is build a peavey FH1 type enclosure to sit under my MEH horn. (my EVM15L models good in it, and works very well in my current midbass horn)

I've had an idea to try and move the acoustic centre of the w bin closer to my MEH so that it will be within 1/4WL at the crossover. I'm going to try and split the wbin along it's longest length so that I can use 2 drivers in a 1.5 way setup. The top driver will run 80Hz to 280Hz, and the bottom driver will probably start rolling off 1st order around 150Hz.

Hopefully this will result in the system operating closer to point source.

The attatched image might explain better.

Thanks,
Rob.

 

[weltersys]

This is for home use, so maximum output is not an issue.
I'm going to try and split the wbin along it's longest length so that I can use 2 drivers in a 1.5 way setup. The top driver will run 80Hz to 280Hz, and the bottom driver will probably start rolling off 1st order around 150Hz.

Hopefully this will result in the system operating closer to point source.

Rob,
I don't think you'll gain anything in terms of being a single point source by splitting the W bin vertically, the center to center distance L/R is greater than the vertical.

The MEH will probably need around 2ms to the W bin will probably require somewhere around 2ms delay to time align.

 

[SpeakerBob]

Rob,
the center to center distance L/R is greater than the vertical.

Hi Art,

I'm not sure what you mean by this ? (I'd be splitting it horizontally btw)

Thanks,
Rob.

 

[weltersys]

I'm not sure what you mean by this ? (I'd be splitting it horizontally btw)

Rob.
The two sides of the "W" are two individual point sources with a longer distance between the L/R sides than the vertical distance between the vertical split.

 

[SpeakerBob]

Thanks for your reply Art, I now understand.

I'll have a look later at my drawings to work out all the ctc spacings. (Ill use XDir)

Fwiw Freddi posted a measurement of his FH1 cabs and the off axis response seems ok for my bandwidth.

Cheers,
Rob.

 

[SpeakerBob]

Hi Art,

The left to right distance is 366mm, which is roughly 1/4WL @ 235Hz.

Maybe easier for me to run a pair of straight horns instead.

Cheers,
Rob.