Neville Roberts remembers the first time he heard a transmission line speaker as he is dazzled by Falcon’s latest addition
My first ever experience of transmission line speakers was in the mid-Seventies when a friend invited me over to hear his newly purchased IMF TLS80. I was impressed by the tight, punchy, extended and well-controlled bass coming from the legendary KEF B139 bass driver. This doesn’t have a conventional paper cone, but rather an expanded polystyrene piston laminated with a thin aluminium sheet. As the piston is solid, it doesn’t suffer from break-up associated with paper cones when operating at low frequencies and being driven hard. Consequently, it can move large volumes of air.
Falcon was founded in 1972 by Malcolm Jones, who had previously worked at KEF as Senior Development Engineer. While there, Jones was responsible for designing many drivers and systems, including the B139 woofer, the B110 midrange driver and the T27 tweeter unit. He left KEF in 1974 to work full time at Falcon Acoustics and when he retired in 2009 transferred the company to Jerry Bloomfield, who himself has decades of knowledge of loudspeaker design, including the IMF range of loudspeakers. IMF was the brainchild of Irving M Fried. In 1968, a British branch of the US company was opened and it was this combined Anglo-American setup that produced the IMF TLS80. The four-way design of this speaker originally used the Celestion HF1300 and HF2000 as a tweeter and supertweeter, a KEF B110A midrange and a KEF B139 bass unit housed in a quarter-wave tapered transmission line. Now, in 2021, Falcon is making brand-new B139s, B110s and T27s, all with the same specifications as the original speakers designed by Malcolm Jones.
The organ note makes my trouser legs flap if I stand close to the exit port
A second IMF transmission line loudspeaker kit, the IMF200 quarter wave, has recently been released to sit alongside its baby brother, the IMF100 eighth wave bookshelf speaker. Like the IMF100, the 200 has a modern look and feel with smooth curved front edges. It has a detachable Tygan cloth grille, which is held in place magnetically. It boasts a three-way design, using a Falcon T27 19mm Mylar dome tweeter, a B110 127mm Bextrene cone midrange unit and a B139 bass driver. The cabinets are available in real-wood veneer finishes including walnut, rosewood (an extra £) and light oak. They are supplied pre-built and made of high-quality Italian Baltic birch plywood, which results in a void-free core with excellent acoustic properties. The crossover uses Falcon’s polypropylene capacitors in both the mid and high-frequency sections.
As with the IMF100, the cabinets, wood veneer and crossovers are all of superb quality. The crossover unit is factory assembled and all the connections for the internal wiring are made using push-on spade connectors, so no soldering is necessary. A pair of Allen keys is provided, along with all the necessary hardware, and an online instruction manual and video are available to help with the construction process – yep, that’s right, you’ll need to build the IMF200 yourself or pay £ for Falcon to do it for you. The instructions guide you through each stage with photographs and clear descriptions, and are very easy to follow. I build both speakers in less than two hours and connect them up to my 300BPSE valve monoblocks.
Before commencing any critical appraisal, Falcon recommends a period of 24 hours of running-in at listening levels to allow the drive units and components in the crossover to settle down. In my experience, the greatest sonic improvements occur after an initial four hours: the bass is much tighter, punchier and well controlled, the midrange is clearer with a significant improvement in imaging and the top end is more refined.
Sound quality
I kick off listening with a superb Chasing The Dragon direct-cut vinyl recording of Rimsky Korsakov’s Capriccio Espagnol played by the National Symphony Orchestra under the baton of Debbie Wiseman. I am instantly impressed by the opening bars of the first movement. The music is spacious and open and the IMF200 delights with a full and uncluttered sound, even during the crescendos. Back in 2017, I attended this recording and listening back now I get a real sense of ‘being there’ in front of the orchestra. The powerful finale has a real impact and the reality of the performance is spectacular. The sharp imaging of soloist players is clearly identifiable and there is no overlap of sound from adjacent instruments. In particular, the bass drum at the back of the orchestra is powerful, punchy and tight – a real testament to the B139 and that transmission line design.
Saint-Saens’ Organ Symphony No.3 played by The City of Birmingham Symphony Orchestra conducted by Louis Fremaux is known for some really deep 16Hz organ note during the first movement (I’ve measured it). During the first movement, the organ playing is full, deep and refined, and portrays incredible power and emotion. The organ note causes my trouser legs to flap if I stand close to the exit ports of the cabinet. This leads nicely into the sprightly second movement, where the drum rolls at the beginning really grab my attention. The violins are bright and cheerful and all the sections of the orchestra are perfectly positioned within the soundstage.
Moving to some classic jazz and the 1960 CBS stereo issue of Miles Davis’ legendary Kind Of Blue. Although this stereo release is a little ‘sax on the left, trumpet in the middle and drums on the right’ it is nevertheless a fantastic analogue recording that has huge presence and dynamics. All of the innate beauty of this recording is well conveyed by the IMF200. In particular, the hi-hat on All Blues is extremely clear and crisp. Overall, the top end is superb and the bass is tight and in perfect proportion to the rest of the instruments.
To check out the IMF200’s handling of vocals, I turn to a recording of Barbra Streisand singing Tomorrow. The vocals certainly stand out in front of the orchestral backing, which is sparkling and clear. Streisand’s voice is in sharp focus and there is a very natural depth to the recording, with her voice being positioned well in front of the orchestral backing.
I finish off with some swing and a superb Capitol recording tape from 1958 entitled Jackie Gleason Presents Velvet Brass. This is a stereo 7.5IPS two-track reel-to-reel tape for in-line heads, which is the professional tape standard and pre-dates the commercial standard of four-track for domestic stereo pre-recorded tapes. Unlike the later 1960 Miles Davis Kind Of Blue stereo LP recording, this tape has a realistic soundstage with the instruments distributed evenly across the width. Although vinyl versions of this recording are available, this early example of a commercially produced stereo tape wins over the vinyl version in terms of a huge dynamic range and excellent instrument positioning. In particular, the saxophone on the right-hand side in Skyliner has a real presence and certainly gets the foot tapping.
Conclusion
The superb-sounding IMF200 gives a modern look to the traditional transmission line designs of old and will certainly be at home in many different environments. The kit itself is a cinch to construct for anyone who can turn a screwdriver. The quality of the components and the finish of the wooden cabinets is extremely high, especially for the price. The IMF200 is an authoritative, refined and elegant loudspeaker that will certainly be at home in many high-end systems
OUR VERDICT
Exceptional- sounding, high-quality floorstanders for an extremely reasonable price, even for the factory-built version10/10
- Superb sound - easy construction
- Nothing at the price