ROGERS LS 5/9

LOUDSPEAKERS

ROGERS LS 5/9 LOUDSPEAKERS Rogers loudspeakers are once more being manufactured in their homeland of the United Kingdom, and the man in charge was, once, well… the man in charge!

Rogers was founded in the UK in the 1970s by Jim Rogers and, back in the day, was one of the top-three speaker manufacturers in the UK, not least because the company owned licences to sell speakers designed by the British Broadcasting Corporation, of which the tiny shoebox-sized LS 3/5A is probably the best-known and is certainly the best-selling of the BBC designs. But one of the best-sounding of the BBC-designed models for Rogers was the LS 5/9 that is the subject of this review. The very best-sounding of the BBC designs was the large LS 5/8, but it never really took off because (1) it was so large and (2) it was an active design, with amplifiers built in.

The LS 5/9 has been out of production for many years, not least because the Chinese company that now owns Rogers, the Wo Kee Hong Group, stopped UK production in the 90s and, when it moved Rogers production to China, simply ceased making this and many other classic Rogers designs, instead developing lower-priced models sold exclusively into the Chinese domestic market.

The great news is that the Rogers LS 5/9 is once more back in production, and that it’s being produced in the UK under the guidance of one of the design engineers who was working for Rogers back in the early 90s, Andy Whittle (See Interview).

EQUIPMENT

The Rogers LS 5/9 is a classic two-way bass reflex design that sees a 34mm diameter soft dome tweeter matched to a 210mm diameter polypropylene-coned bass/midrange driver.

The tweeter is an Audax TWO34XO that’s made in France, to the front face of which Rogers fits what it calls a ‘dispersion loading protective plate’ in the form of an enormously strong non-ferrous perforated dome. The dome not only protects the 34mm soft dome from potential damage, but also modifies its high-frequency output and dispersion. I suspect that back in the day the BBC engineers added the dome simply to protect the tweeter from being damaged, because the LS 5/9 was intended to be used as a broadcast monitor in mobile studios, though I have no doubt that its effect on sound quality was factored in. It’s said that the dome was designed to be able to support the entire weight of the speaker cabinet, should it accidentally fall forward, and judging by the protective dome’s construction, I’m sure it could do that… and more! In any event, the dome is able to be removed, so you can choose to use it or not.

The TWO34XO is actually a replacement for the original tweeter that was used on the LS 5-9 in the 90s, which was an Audax HD13D34H.

This new version has a higher power-handling capacity (despite not using ferrofluid) along with a more extended and rather more linear high-frequency response. But its frequency response is not that much more extended, because the operating bandwidth of the TWO34XO is rather different to that of most tweeters, since its very low resonance frequency (800Hz) enables it to be used down to a much lower frequency than most tweeters, the result of which is that it doesn’t go quite as high in frequency as most tweeters. It’s also rather unusual in that it has a replaceable voice-coil.

My recollection was that the original bass/ midrange driver in the LS 5/9 was made by KEF, though I stand to be corrected. The one that’s now fitted to the Rogers LS 5/9 is one that Andy Whittle says he ‘reverse-engineered’ from the original and is having made in China. The cone certainly looks like the original, with an almost-see-through opaque polypropylene cone that despite being rated by Rogers with a diameter of 210mm has an actual cone diameter of 155mm. Even if it were 210mm in diameter, the driver is mounted from behind the baffle, so it has to deliver its sound through a hole cut in that baffle, and that hole has a diameter of 175mm which would therefore be a limiting factor. (The Theile/Small diameter of the driver is around 160mm, for an Sd of 202cm².) At the centre of the cone is a black fabric dustcap whose diameter of 30mm would seem to suggest that that this is also the diameter of the voice-coil.

The frame (chassis) of the bass/midrange driver in the new LS 5/9 is completely different from that of the original, because whereas the original driver had a cast alloy frame, the one on this new LS 5/9 is made from pressed steel.

But if the tweeters are a newer version of the original, and the bass/midrange drivers are a reverse-engineered version of the original, the crossover networks on my review samples were totally original, having been manufactured back in the 80s by Rogers itself (actually, they were manufactured by Swisstone, which owned the Rogers brand at the time). This means that they use the famous Evox MMK capacitors which were made by Evox Rifa but became unavailable after that manufacturer was purchased by Kermet Capacitors. Whereas the original Evox MMK capacitors used metalized paper, the ones that are now available use metalized polyester. The paper versions are prized by audiophiles for their sound quality and go for big bucks on Ebay.

I was a bit surprised to find thirty-yearold crossover networks inside a loudspeaker made in 2020 so I asked Australian Hi-Fi editor Greg Borrowman to do some digging for me. It turns out that when Rogers decided to put the LS 5/9s back into production it had a considerable quantity of the original crossovers still in stock (New Old Stock, or NOS as it’s known in the trade) so it used these old crossovers in its initial production run, of which my review samples (CLS30A/ CLS30B) must have been a part. They have apparently since run out of these already, but according to Andy Whittle, of Rogers, the new crossovers “are essentially the same” and deliver 18dB/octave slopes either side of a 3kHz crossover frequency. “Essentially the same” would mean three iron-cored inductors, five wirewound resistors, seven MMK capacitors and eight carbon resistors — so quite a complex design.

Whether it’s new or old, the crossover design itself is unchanged, and this design includes the ability to adjust the tweeter level though four different settings — +1dB, 0dB, –0.5dB, –1dB.

However, if you want to make the adjustment you’re going to have to be pretty handy with a soldering iron, because in order to make it, you have to de-solder a flywire from one terminal on a printed circuit board fitted to the front of the front baffle, then re-solder it to whichever of the other three terminals you wish to use. And of course you have to do this for both speakers.

I have to admit that this is one aspect of the LS 5/9’s design that I personally would have updated, possibly by using gold-plated sockets and a re-insertable fly-lead, so changes could be made quickly, and no soldering would be required. But I guess that Rogers was aiming for authenticity. As for why a monitor speaker, designed and engineered for the highest accuracy possible, would have enabled the level of its high-frequency output to be adjusted in the first place is a bit of a mystery.

One long-toothed engineer of my acquaintance told me that the adjustment was provided to account for sample-to-sample variations (aka inconsistencies!) in the original Audax tweeter but I personally doubt this would have been the case, because it would have been easier and cheaper for Rogers to simply measure all the tweeters and reject the ones that were out of specification. Or if this was true, and Rogers had to work around inconsistent tweeters, it still would have been easier and cheaper to measure them individually add the necessary attenuation resistor to the tweeter itself. But whatever the reason was back in the day, it is highly likely that brand-new modern Audax tweeters are far more consistent than the originals. But this is all idle speculation. I suppose the takeaway from the provision of the adjustment is that irrespective of whether it makes sense or not, Rogers LS 5/9 owners have the ability to modify the high-frequency output of their loudspeakers.

The front-firing bass reflex port on the LS 5/9 also appears to be identical to the original: a simple black plastic tube that is 64mm in diameter and 95mm in length. Again, I would have been tempted to flare the port at both ends, but Rogers is once again being faithful to the original design.

The cabinets are also built in the great ‘BBC’ tradition, being made of very thin material (9mm Russian birch ply) whose top, bottom and sides are all butt-joined and reinforced by four struts running frontto-back. As for the baffle and the rear panel, these slide inside the resulting structure where they’re fixed to struts running topto-bottom and side-to-side.

Rogers LS 5/9 owners have the ability to modify the highfrequency output of their loudspeakers

Bituminous pads (from Clarity Acoustics) are stapled to all panels (including the baffle) to provide damping, and all panels except the baffle have egg-crate foam slabs glued over the damping. There’s also damping material sandwiched between the rear of the Audax tweeter’s magnet and the crossover PCB. Three standard wood veneer finishes are available for the LS 5/9 cabinets — olive, rosewood and walnut — but Rogers says other finishes are available via special order should you so wish.

The frame that supports the thick, fairly rough-weave cloth used for the speaker grille is a ‘picture-frame’ style so there are no cross-struts to affect dispersion.

The cloth on my sample was Black Tygan which is a heavyweight woven nylon. My understanding is that this cloth is no longer made, so presumably Rogers had some of this in stock as well. The grille attaches via Velcro strips that run around the entire periphery. Removing the grille requires that you grasp a small cloth loop that protrudes from the bottom of the grille and pull moderately hard. Sustained pressure does the trick, so the Velcro loosens its grip gradually. I personally would have modified the design by replacing the velcro with magnets.

The rear of the speaker is almost completely smooth, because there are no protruding speaker terminals to be seen.

Instead there are just two 4mm-diameter banana sockets that are almost completely recessed inside the cabinet, meaning that no matter what type of speaker cables you use, you’re going to have to terminate them in banana plugs.

As for the cabinets themselves, they’re 460×275×285mm (HWD) and each one weighs 12kg. When the BBC used the

LS 5/9s they placed them either on open stands or on open frames fixed to a wall, so both are viable options for home use.

LISTENING

I can guarantee that the first time you listen to a pair of Rogers LS 5/9s you will immediately wonder to yourself how so much great sound could be issuing from such a relatively small pair of loudspeakers. I will also guarantee that once you’ve listened just a little longer, you’ll have forgotten your immediate wonderment, indeed you’ll have forgotten about the speakers altogether. You’ll instead be just lying back, with your eyes closed, totally relaxed, enjoying the music that’s issuing from them.

Because that’s what these speakers do. Their delivery of music is so smoothly presented, so beautifully balanced and so sweetly delivered that they’ll just sing to you in your listening room.

The level and extension of the bass you will achieve in your room from the Rogers 5/9s will of course depend on how you decide to mount them and where in your room they’re positioned, but if you get it right, you’re unlikely to yearn for more unless you’re into pipe organ music, techno or classical orchestral music at high volume. And if you do fall into one or more of these categories I would suggest adding a subwoofer. I used my review pair of LS 5/9s on open metal frames a friend of mine welded up for me for use with a similarly-sized pair of UK speakers that I have long since sold. (The buyer wanted the speakers, but not the frames… and I have to admit they looked a bit rough, even though I thought I’d painted them beautifully.)

I found the Rogers 5/9s were more than capable of delivering the sound of a kick drum at usefully high volume levels and also the lowest notes on an electric bass guitar at similar levels, which in real terms means that the bass delivery will be more than sufficient to cover the lowest frequencies most people are going to need to replay when playing their favourite music at the levels they’re most likely to be playing it. Not only can the 5/9s deliver great bass at these levels, they do so with impressively low distortion and more than a goodly amount of speed.