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<blockquote data-quote="Jon Waller" data-source="post: 116467" data-attributes="member: 825">Re: JBL Versus RCFJust my 2 cents on the annular HF driver design.1.&nbsp; The first annular diaphragm HF driver I am aware of was from JBL.&nbsp; I have a 1971 JBL Professional catalog with the 2405 Ultra-High Frequency driver listed.&nbsp; This is the slot-loaded driver.&nbsp; Surprisingly, the bullet version of this driver is not listed, apparently that came later.&nbsp; These drivers have been copied by many other companies in the decades since.2.&nbsp; I have a spec sheet from Cerwin-Vega I picked up at a NAMM show about 12 years ago for their then new BC Horn Drivers (BC-101, BC-201, BC-301) that had annular (ring) diaphragms.&nbsp; This spec sheet was marked &#039;Preliminary&#039;.&nbsp; I don&#039;t know if they ever made it to production.&nbsp; I do recall that around that time period there was a paper I saw in the JAES from a group of Russians that were working at Cerwin-Vega.&nbsp; Possibly one of those men is now the person with JBL, since both companies are/were located in southern California.3.&nbsp; In my own limited experience with current annular diaphragm drivers from two different manufacturers, both the subjective and measured harmonic distortion is higher than in a comparable output dome diaphragm driver, by up to 10 dB on one of the harmonics when driven at high power in one case.&nbsp; The frequency response of the annular drivers is much smoother at high frequencies, and their impulse responses and spectral decays are better, however, since they do not suffer from &#039;multi-path&#039; in the phase plug and diaphragm breakup.</blockquote>

[QUOTE="Jon Waller, post: 116467, member: 825"] Re: JBL Versus RCF Just my 2 cents on the annular HF driver design. 1. The first annular diaphragm HF driver I am aware of was from JBL. I have a 1971 JBL Professional catalog with the 2405 Ultra-High Frequency driver listed. This is the slot-loaded driver. Surprisingly, the bullet version of this driver is not listed, apparently that came later. These drivers have been copied by many other companies in the decades since. 2. I have a spec sheet from Cerwin-Vega I picked up at a NAMM show about 12 years ago for their then new BC Horn Drivers (BC-101, BC-201, BC-301) that had annular (ring) diaphragms. This spec sheet was marked 'Preliminary'. I don't know if they ever made it to production. I do recall that around that time period there was a paper I saw in the JAES from a group of Russians that were working at Cerwin-Vega. Possibly one of those men is now the person with JBL, since both companies are/were located in southern California. 3. In my own limited experience with current annular diaphragm drivers from two different manufacturers, both the subjective and measured harmonic distortion is higher than in a comparable output dome diaphragm driver, by up to 10 dB on one of the harmonics when driven at high power in one case. The frequency response of the annular drivers is much smoother at high frequencies, and their impulse responses and spectral decays are better, however, since they do not suffer from 'multi-path' in the phase plug and diaphragm breakup. [/QUOTE]

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