Full Range Horns

Product: Loth-x Polaris
Manufacturer: Loth-x
Cost: approx 4700 UKP
Reviewer: Geoff Husband

Introduction

A few years back I owned a pair of Naim amps and dutifully logged into the Naim forum. Nicely run it was too, if a bit 'samey' i.e. "I've a 62/140 should I buy a Hi-cap?" But enough of such trivia. The point is that like many 'one-make' forums the views of other equipment bordered on the rabid... The favourite target was the 'single-ended' gang with their propensity for pathetic power outputs and horn speakers, usually Lowther based. The latter garnered comments like "bass and treble filters", "the most coloured cabinet ever made" and "makes you want to put lead in your ears".

Years passed and my Naim kit was replaced with valves and I started to come into contact with people who worshipped the god 'horn' and saw anything with more than one driver as some sort of misguided aberration.

So does the truth lie between these extremes or as with so much in hi-fi is it that what constitutes a good sound depends on where the listener is coming from?

To find the answer I've done a fair bit of research into horns and single driver speakers. One experiment with a ported box containing a Fostex 204 gave me hints of what might be possible. Fast, exciting but resolutely mid forward with no bass to speak of and strong 'papery' colourations.

Construction

Which brings me in my normal rambling way to the speaker on test, the Loth-x Polaris. This is a big, full-range horn - though the smallest in the Loth-x 'Stamm' range. 135*35*50 cms is BIG by my standards... The horn mouth dumps into the room at the front like a Lowther Accousta though the baffle is narrower in the modern tradition.

There are a several back loaded Lowther horns that take this form, though the folding inside the cabinet varies from design to design and so I'll not comment on how tortuous the horn throat is in this case. The relatively small horn mouth inevitably limits the level of the lowest notes (a horn capable of going to 20 Hz would fill a wall). All in all a rather conservative (classic?) looking horn design albeit beautifully put together and very heavy (90+ kgs...)

Conservative in all but one area - The driver. Where in just about every other such horn you'd see a Lowther looking out at you, here we have a unique full range driver, The 'Stamm' designed for Loth-x. Why? The world is sold on the idea that Lowther make the best full range driver in the world so why not just take a stunning cabinet and sit back and wait for the orders. Designing and producing a unique driver seems economic madness - unless it's very special.

Loth-x were very keen I shouldn't look on the Stamm as a Lowther substitute, but I honestly believe that for the buyer it's a comparison that will inevitably be made. Look carefully. Lowther make great play of using the most powerful magnets available, their top models producing a field of 23,000 gauss. Precisely what Loth-x claim, though their magnet (alnico) is said to be computor designed to maximise the flux around the voice coil. The cone of the Lowther is cream paper/parchment - so is the Loth-x driver, though in this case it's laquered to protect it against changes in humidity a known weakness of Lowther drivers. Lowther claim to make the most efficient drivers in the world, the Polaris claimed 104 dB, well into Lowther territory and easily driven by a 3 watt SE amp for example.
Whilst the Lowther is a dual cone with the characteristic Voight 'whizzer' cone taking over high frequencies, the Loth-x driver has a third cone - little more than a lip next to the phase plug, it is claimed to extend high frequency response. Where the Lowther chassis is a good quality cast alloy frame the Loth-x goes in for a gorgeous CNC machined faceplate/chassis. Lowther owners live in fear of dust in the voice coil gap and the damage caused by switch on thumps - the Loth-x comes with no such warnings.

You see my point? It seems Loth-x have decided to take on Lowther by addressing the known weaknesses of that driver and building on its strengths. Whether the end result is a Lowther eater is another matter but there's no doubt that Loth-x should be congratulated on taking the difficult route rather than following the herd.

Comparisons aside the driver is beautiful - justifying a large slice of the asking price on its own. You'll want to leave off the dust covers to show off the delicate origami of the cone - looking for all the world like some insects wing. The phase plug is turned alloy complimenting the grey anodized, CNC'd, hexagonal faceplate with its heavy allen bolts. The cabinet is massive and heavy with proprietry damping though the details remain secret. As for WAF/HAF Kate has taken a dim view of various speakers that have passed through here. I feared these monsters would be the last straw, but she loved their classic looks and the fact that they worked hard up against the wall made them less obtrusive than smaller stand mounts. She also liked the neat holes at the bottom for record storage....

Sound

I sort of knew what to expect. Horns by reputation are bass light and mid forward so to speed the acclimatization I used the Cabasse Sloops for a week prior to the Polaris' arrival. This also coincided with Steve Davey visiting when we had a listen to several different floor standers over a weekend. Putting the Polaris on couldn't have been more of a surprise. You see, back loaded Lowthers often show a big mid range peak around 2-3 kHz giving tremendous projection and an 'in-your-face' presentation. Both Steve and I felt the Loth-x if anything a little 'flat'. No peak at all. Putting them through a simple room response test showed a trace that was flat from 100 to 3000 kHz +/- 3kHz. This is as flat as any speaker has ever measured in my room - the last thing I expected from a big horn - normally a ruler flat response is the last thing you expect. Bass rolled off early but very smoothly, no humps and bumps, and the treble looked like a decent tweeter had kicked in - remarkable and very surprising.

The sheer weight of the Polaris' meant that speaker swapping stopped for the day. Soon the Polaris were giving their best hard against the wall, 1 m. from the side walls and toed in to face the listener. From our initial reaction that they were a little 'flat' we slowly slipped into one of those sessions into the small hours where you pull disc after disc out just to see what it sounds like. At the end of the weekend Steve asked me how much they cost. When I told him he just said "good - at least I know I can't afford them..."

So what is the magic? Regular readers will know of my bass heavy tendencies, here we have a speaker the size of a small wardrobe that has a bass response 3 dB down at 40 hz compared to a pair of 11 ltr Morel based ported boxes I had to hand... But... But... Bass lines I'd never picked out came out clear as a bell - the bass was so FAST! "Wonderful bass line" was a comment I found myself making a lot over the next few weeks. If you want to hear what Paul Jones was up to on 'The Lemon Song' these are the speakers to tell you. They won't shake the walls but weight takes on much less importance when faced with such incredible definition. Listening to Sade I never realised what a class act the bassist was, though the simply stunning projection of her vocals, all silk and tears made it easy to miss.

Imaging was good both in depth and width if not of the pinpoint variety, though there was a immense impression of size and scale to everything that was addictive.

Then there's the coherence. As music build to a climax, Nirvana's 'Nevermind' for example, everything holds in place, images don't shift or instruments blur together, it just gets BIG...

Timing... I'd heard (mostly linn fronted) systems time Los Lobos' 'Be Still' better than my set-up. I'd thought that I'd sorted this aspect out, but the Loth-x's made me rethink completely where the problem lay so beautifully did everything fall together.

What about texture? No speaker I've heard has made such a good stab at reproducing the piano with its savagely difficult harmonic structure. Guitar chords had all their strings (12 on occasion), and voices - simpering like Rikki Lee Jones, crooning like Brian Ferry, sneering like Johnny Rotten the Loth-x's captured it all. This could be a double edged sword. No speaker has showed such a difference between a warm CD player and a cold one, ditto for cartridges where I had to play a side of music before the Xv-1 came on song. But here you can't blame the Polaris for telling the truth. It also made me very careful over cabling and revealed more than ever how Sunday nights electricity had magic rather than rubbish in it.

But the moment I knew I was listening to something very, very special was when I put on the Nutcracker. I'm not a classical music fan, but never have any speakers produced the illusion of an orchestra like the Polaris did. The volume was set quite low for the quiet bits, then for big climaxes the Polaris' just demolished the rear wall and blasted out. Dynamics? Never heard anything remotely like this

After the praise what about the brickbats?

First the Polaris' knock one 'Horn' characteristic on the head. They're not mid forward. They do have a slight 'shouty' quality on occasion giving the slightest hint of the 'cuppy', 'papery' colouration dual cone speakers have. Loth-x sent one of their 300b SE amps (test soon) which generally smoothed over this - a match made in heaven?

Really low bass is lacking, but the output over 50 Khz is enough to kid you if you've not heard the real thing, especially as it's so fast and punchy. Though the bass did things I'd never heard before it did have one problem. On a few records with a 'walking' bass line the texture of the bass altered as the horn 'crossed-over' to the driver. Simply Red's 'Sad old Red' was a case in point. The first few bass notes sounding softer that those higher up. That said the complexity of each note's structure was uniquely portrayed and so good is the reproduction I retain a nagging doubt that the change in texture may be on the disc and other speakers mask this - it's impossible to tell.

At the top end metallic sounds like cymbals sounded a little restrained (see postscript), lacking sparkle and shimmer, the upside of this being that it sounded natural - other speakers shimmering cymbals sounding artificial in comparison. Going back to the Simply Red track, the cymbal sounded 'right' but laid back.

Lastly though detail retrieval was exceptional overall there were odd times where things were pushed back in the mix more than I expected - Madonna's 'Till Death Do Us Part' had her swallowing the "he's" (no comments please...).

Compatability

These are high end speaker and deserve similar care with their partnering equipment. My Audions again proved to be great allrounders, but the SE amp Loth-x provided certainly smoothed over some of the cracks that the Audions possessed. With 5000 pounds spent on speakers you might be tempted to spend equally large amounts on ancillaries, but there are alternatives. With their huge efficiency there are SE amps of 2-4 amps that would fit the bill completely and come in at under 500 pounds. Add a second hand vinyl front end - 500 pounds for an LP12 Ittok + decent cartridge and you're left looking for a phono stage (interesting review soon!).
So 6000 pounds would get you a system to die for. Add the fact that speakers like this are never going to go out of fashion or be superceded and you could be using them 20 years down the line. Putting 5000 pound speakers at the head of a 6000 pound system might be turning accepted wisdom on it's head but with only a couple of watts needed it's definitely a viable option. This makes them 'cheap' compared to more conventional 5000 pound rivals which as often as not require massive and expensive transistor monsters to keep their cones under control. Just don't expect the Polaris to work well with a cheapo transistor amp, I tried it and the Loth-x's were ruthless, besides needing only a couple of degrees of volume control to blast your ears...

Conclusions

Horn speakers do things that nothing else will. The huge efficiency allowing for purist valve amps being one, and the matchless projection of vocals another. Speed and timing I've already covered and nothing I've ever heard gives such dynamics. But I think it would be fair to say that most have an Achilles leg rather than heel. Poor low bass, attenuated treble, fierce mid being just three, plus of course the fact that their large complex cabinets and expensive drivers mean that you can buy a hell of a lot of conventional speaker for the money.

That said the Loth-x seem to have addressed the horn's weaknesses, particularly the mid forward nature, to the point where they have an Achilles foot (enough of that analogy I think). Apart from the hideous price they are a horn for everyone, until the fireworks start you could believe you were listening to a good ported box like the Cabasse Sloops. That they still manage to do things like nothing I've ever heard makes them objects of desire for me at least. If you have the sort of deep pockets needed for such speakers then if you can track down a dealer go and listen. You may prefer the low colouration of Quads or the sheer slam of a Naim DBL but rest assured that the Polaris will do things that other loudspeakers merely hint at. If those things are important to you, and I fear they are to me, then personal Nirvana will take you into the world of SE amps, vinyl and speakers like the Polaris. If not you'll just have to write into the Naim forum:-)

And to illustrate the point, last week I was in the control room of a studio listening to their active ATC monitors. Huge powerful bass, slam and tremendous detail. I didn't point out to the engineer that the speakers in residence at my home made them sound hopelessly slow and overblown, a parody of what was going on in the studio. Few studios will use the Loth's - I think they may well be missing out ...

When they were delivered in their crates it took four people to bring them into the house. It took five to get them out again, four to carry them and one to hold me off...

Postscript

Reviewing equipment is usually a pleasant job. With the Polaris it was heaven and hell. The heaven is obvious, the hell was that weighing 90 kgs each swapping speakers for comparison purposes was VERY hard... As a result I did this at the beginning of the review period after allowing for the recommended (by the manufacturer) 3 day running in period. Over the next three months the Polaris provided me with the most exciting musical reproduction I have ever experienced. When they were taken away it became obvious that the 3 day period was utterly inadequate and that the speakers that left were an order of magnitude better than those that arrived. My comments on the treble being relatively restrained were totally unfounded - fully run in I would put high frequency extension and quality above that of either the IPL's or Sloops. Likewise both these worthy speakers were left trailing in every hi-fi and musical attribute you care to name with the sole exception of bass extension compared to the IPL's. I don't want to go over the top here, but at the moment nearly 5000 pounds seems perfectly reasonable in the context of the lead they have over 1500 pound speakers.

Full Range Drivers and the Doppler Effect

For years a few audiophiles have sworn that full range drivers such as Lowthers and the new Loth-x have a magical coherance. One possible reason to justify this claim may be linked to the 'Doppler' effect.

We've all heard this. It's when a cars engine note is higher as it approaches - the cars speed brings the wave fronts of the noise closer together raising the pitch, then the note lowers as the car passes as the wave fronts become 'stretched' apart by the cars speed as it receeds.

When applied to recorded music the theory goes that a microphone or pickup has a diaphragm. This moves back and forth with the sound waves vibration, slowly for low notes, fast for high notes. If a microphone diaphragm picks up a low and a high note simultaneously the slow movements of the low note will modulate the high frequency. If the diaphragm is moving forward with the low frequency wave the fast high frequency waves will come closer together giving a higher tone than strictly correct and visa versa.

Now to a two-way speaker where the high note is handled by a tweeter. This tweeter, given the modulated high frequency signal, will send out a tone which will rapidly vary in pitch depending on whether the original microphone diaphragm was moving forwards or backwards at the time of recording. If the original low tone was 50 Hz the pitch of the high tone will rise and fall 50 times a second. The low tone will be reproduced by the woofer completely separately.

A full range driver should move in exactly the same way as the original full-range microphone diaphragm thus decoding the modulated tone to give a steady tone.

Of course music is a mass of different frequencies each modulating the other, only a true full range drive unit will 'decode' this information. If this holds true a full ranger should remain coherent no matter how complex the music. It may also time better for much the same reason.

To add to this the full range driver lacks a crossover with all the associated problems of energy loss, storage, phase change and information loss from all the wire/joints/plugs etc.

Of course the snag is to get such a driver to provide at least some bass down to 50 hz, cover the principle audio spectrum from 100-10000hz in some kind of linear manner and provide worthwhile output up to 2Khz and beyond. It's a very tall order indeed and drivers capable of pulling it off are very expensive, rare and need a horn to bolster low output...