Loop check for Reactance Annulling

84.105.197.130

Posted on April 29, 2016 at 12:01:57

mdg
Audiophile

Posts: 51
Location: Gilze-Rijen (Holland)
Joined: November 27, 2004

Hi all,

Does anybody know if you can relate an acoustic measurement (impedance or frequency response) to the subject reactance annulling.

How you can be sure you have a hornsystem with the most optimum alignment in terms of effiency?

gr. Marcel

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RE: Loop check for Reactance Annulling

Saturntube

06:04:32 05/03/16

RE: Loop check for Reactance Annulling

Bill Fitzmaurice

13:30:24 04/29/16

2

RE: Loop check for Reactance Annulling

mdg

06:24:39 05/01/16

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RE: Loop check for Reactance Annulling

Saturntube

06:04:32 05/03/16

RE: Loop check for Reactance Annulling

Bill Fitzmaurice

13:30:24 04/29/16

2

RE: Loop check for Reactance Annulling

mdg

06:24:39 05/01/16

RE: Loop check for Reactance Annulling

Bill Fitzmaurice

08:47:07 05/01/16

RE: Loop check for Reactance Annulling, posted on April 29, 2016 at 13:30:24

Bill Fitzmaurice
Industry Professional

Posts: 5371
Location: New England
Joined: October 20, 2002

>How you can be sure you have a hornsystem with the most optimum alignment in terms of effiency?

Model it in HornResp. The effect of altering the rear chamber size, or anything else for that matter, is easily seen. If you want to see the optimum result possible with a given driver use the System Design tool. If you want to check whether an existing enclosure meets the design specs compare the measured impedance to the predicted.

RE: Loop check for Reactance Annulling, posted on May 1, 2016 at 06:24:39
mdg Audiophile Posts: 51 Location: Gilze-Rijen (Holland) Joined: November 27, 2004	Hello Bill, Thx for your reply. Would the resonance curve in the impedance plot be less wide, because the hornis more resistive? There are a few papers about the subject reactance annuling but none of them a talking about how this can be checked with measurements and what to look for. gr. Marcel

RE: Loop check for Reactance Annulling, posted on May 1, 2016 at 08:47:07

Bill Fitzmaurice
Industry Professional

Posts: 5371
Location: New England
Joined: October 20, 2002

To simplify what happens without the complex math, the air mass in a horn adds to the Mms of the driver, effectively reducing its resonant frequency. If said resonant frequency is too low the horn loses sensitivity near the cutoff frequency. Reactance Annulling is a three dollar term used to describe using a small rear chamber to raise the effective driver resonance back up to where it's the same as the horn cutoff frequency, giving higher sensitivity near Fc. When the rear chamber size is correct there will be a major impedance peak at Fc. When it's too large the peak will be below Fc. When the chamber is too small the peak at Fc has value drops, or disappears entirely.

RE: Loop check for Reactance Annulling, posted on May 3, 2016 at 06:04:32
Saturntube Manufacturer Posts: 331 Location: Austin Joined: April 21, 2006	There are some big threads about that here, do a search, a lot of contradicting opinions.

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Loop check for Reactance Annulling

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