Monday, March 9, 2020

Loudspeakers With Rear-Firing Tweeters: The Least Room Fussy Hi-Fi Loudspeakers?


For the budget audiophile skeptical about acoustically treating your listening room, are loudspeakers with rear-firing tweeters the best value-for-money solution?

By: Ringo Bones

Budget-conscious audiophiles had always been skeptical about “pricey” acoustic room treatments. They argue that their listening rooms …” is neither a recording studio, nor a mastering or recording post-production studio…” And both anecdotal and empirical evidence seems to reinforce this very idea by the time they manage to afford those relatively pricey second hand Quad electrostatic loudspeakers either the original ESL 57 from the 1950s or the newer one and far more common ESL 63 from the early 1980s. In practice, loudspeakers with rear-firing tweeters and their more elaborate counterparts – i.e. bipolar loudspeakers that radiate sound in both the front and the back – excel at sounding as if the very recorded acoustic event is actually happening in your listening room reproduced with timbral accuracy that conventional monopolar loudspeakers (i.e. those that radiate sound only in the frontal 180-degree arc) seem to lack. But in all things audiophile, not all bipolar / dipolar / loudspeakers with rear firing tweeters are not created equal.

Back when the late, great Audio Hall Of Fame speaker designer Arnie Nudell released the Eosone RSS series back in the early 1990s, many budget-conscious audiophiles got their first exposure of a budget loudspeaker that can reproduce the timbral accuracy of the cymbals in a basic rock combo drum-kit. But there are bigger, pricier ones that are found to be wanting from this time period.
Despite of the brownie points earned for a clean, full sound in a majority of hi fi magazine reviews, the Snell Type B loudspeaker was criticized by more than a few audiophiles as having its rear-firing tweeter for being a tad too loud. Some even suggested gluing a penny over the rear tweeter in order to make it sound better. Maybe a better solution is for the designer (s) of the Snell Type B to incorporate an l-pad attenuator / rheostat in the first place to attenuate the rear tweeter to make it around 12 dB SPL quieter than the front tweeter while preserving its high-pass filter crossover point or maybe include an on-off switch for the rear tweeter in “worst-case scenarios” for an overly bright listening room.

Bipolar loudspeakers – especially those manufactured by Mirage as in their Bipolar series - gained popularity back in the 1990s due to their rather “psychedelic phasiness” that they introduce to electric guitar recordings. Though criticized for not exactly accurate, they could take this effect too far by making those early Eric Clapton recordings when he’s playing through a small-ish tweed guitar amp, most bipolar loudspeakers tend to make tweed guitar amps sound acoustically small despite of the rich harmonics of the tone being produced. And sometimes bipolar loudspeakers exaggerate the “acoustical size” of some famous electric guitar recordings – i.e. that era when Eric Clapton preferred Gibson Explorers played through Marshall full stacks.

Open baffled loudspeakers – especially ones with an open baffle midrange configuration -  are praised for reproducing female vocals with a timbral accuracy as if there was no microphone and onstage monitor loudspeakers - in short, the timbral accuracy of an unamplified female voice. Despite of their virtues, open baffle loudspeakers have one glaring shortcoming, they could sound devoid of any extraneous reverb bas in they sound drier than “Prohibition era Georgia” when paired with a very low jitter digital front end. This effect is very noticeable on electric guitar recordings that are injected directly into the mixing board with distortion and tonal effects only in the preamplifier level – as in the timbral roar of the 1980s era hair metal guitar solos championed by MTV. 

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