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Author Topic: use of 1.4 inch and 1.5 inch drivers on 2" throat horn lenses  (Read 6544 times)

Gary Perrett

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Hi,
With the advent of 1.4", and 1.5" Drivers what is the best way to handle the problem of a lack of suitable horns in that throat size? Now I know there are adaptors, but what effect is there on the sound if you use an adaptor, or just bolt up to a 2" horn" for that matter? Is there any benifit to using a dedicated 1.4/1.5" "correct" size opening, horn.

Thanks
Gary
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bgavin (Bruce Gavin)

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Re: use of 1.4 inch and 1.5 inch drivers on 2" throat horn lenses
« Reply #1 on: July 12, 2005, 06:26:49 pm »

My experience is with the JBL 1" to 2" adapters.

These continue the horn flare between the 1" and 2" ends of the adapter.  The adapter effectively adds a few inches additional length to the horn air column, lowering the Fc somewhat.  This increases power handling at the low end of the horn passband.

This insures the proper taper in the critical area of the horn throat.  Attaching a 1" driver to a 2" horn destroys the critical taper in the throat.
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Graeme Goodacre [Centauri

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Re: use of 1.4 inch and 1.5 inch drivers on 2" throat horn lenses
« Reply #2 on: July 12, 2005, 06:55:16 pm »

The only difference between the 1.4" and 2" exit drivers is the removal of the "snout" between the phase plug and driver exit.  This snout section was usually a low flare rate, resulting in less than ideal high frequency loading of the driver in real world conditions.  By removing this section, the desired flare rate can be established from the phase plug, resulting in better HF performance.  I would think any adaptors you could get to adapt to a 2" throat would also suffer from the low flare rate, negating the advantage of the 1.4" driver.

Bolting it direct to a 2" flare would give a discontinuity, producing reflections/refractions.  A bit a surgury with fibreglass or body filler on the throat of a 2" flare to give a smooth transition to the correct size would probably work ok - the faster initial flare rate would give better HF loading.

I think there is a white paper on the JBL site regarding this.

Cheers
Graeme
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Al Limberg

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Re: use of 1.4 inch and 1.5 inch drivers on 2" throat horn lenses
« Reply #3 on: July 12, 2005, 07:56:23 pm »

While the JBL 1.5" only goes back about 10 years, EV, Altec, Radian and Emilar (I suspect maybe a few others as well) were making 1.4" well over 20 years ago.  Community offered the 1.4" throat on most of their horns dating back till at least the mid 70s and DDS offers several models in both 1.5 and 1.4 today.
 The white paper that Graeme refers to it should be noted probably only applies to JBL's approach to their 1.5" .  The pertinent Emilar and Radian 1.4" and 2" drivers are duplicate in design with the throat size being made smaller by a small plastic insert in the 2" hole of the 2" but they never used the deeper 'snout' like the JBL 2".


HTH,
Al
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sheldon harris

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Re: use of 1.4 inch and 1.5 inch drivers on 2" throat horn lenses
« Reply #4 on: August 07, 2005, 12:21:18 am »

i think peavey sells an adaptor that is 1.4 or 1.5 inch to 2 inch. the same one that comes with the 44xt driver.
only costs about 20.00
that would solve the problem. Smile
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