LOWTHER SPEAKER TECHNICAL DISCUSSION

from CommonSense Audio


Introduction

Lowther speakers are among the finest speakers on the planet regardless of price. That's quite a statement. But if you talk to anyone who's had the opportunity to hear Lowther speakers in a great cabinet, the vast majority will agree. Even the world's so-called greatest speakers--Wilson Grand Slamm, JM Labs Grande Utopia, Genesis 1, Dynaudio Evidence, etc. (all over $50,000/pr) can't compare. Yes--given that they are enormous speakers--they have more dynamics. But they fall far short in the true tests of a great speaker--realism, clarity, accuracy, speed, lack of distortion, phase accuracy, time delay, imaging, soundstage, and efficiency.


Lowther Speakers--Some Background

I'm sure many of you will be astonished to find out that a single speaker can cover the full audio spectrum. Magazines, audio dealers, and others have tried to convince people that at least two speakers are necessary for the full spectrum of music. That is just not the case. It is true that many so-called 'fullrange' speakers do not, in fact, produce the full musical spectrum. These might be more properly called 'extended range' speakers. However, there are several companies that produce 'the real thing.' Lowthers were the first to accomplish this.

Many of you will be unfamiliar with Lowther speakers. Although they have been available for more than 70 years, they were never mass marketed in America. Following is a brief description of Lowthers and what makes them so different (and so much better) than almost any other speaker.

1. A Lowther speaker is fullrange. No separate woofers, tweeters, or crossovers are necessary. Without trying to blend different sizes and types of speakers together, there is a purity of sound that just can't be described. Also, all of the distortion and phase shifts produced in 'normal' speakers--when a crossover changes the sound from one speaker to another--are eliminated. Best of all, the music doesn't pass through any inductors (coils), resistors, or capacitors. A crossover is a necessary evil in all other speaker systems. With Lowthers, there is no crossover to deal with. Most Lowthers are rated 30 to 22,000 cycles and I have personally tested them as flat (-3 dB) to 40 cycles in actual listening rooms.

2. The sound from a Lowther comes from a single point in space. This gives perfect imaging and soundstage. Common sense tells you that when someone sings, sound doesn't come from their mouth, their hips, and their knees (like it does in so-called 'normal' speakers). In addition, there are no time alignment problems (one speaker being farther from the listener than another), because the sound comes from a single speaker. You have never really experienced stereo imaging until you listen to Lowthers. Where the artist was previously 'in the middle', now that artist 'holographically' appears as a real human being. It's an amazing experience.

3. Lowthers have the strongest magnets in the world. Lowthers have such strong magnets that the flux densities in the magnetic gap (the 'motor' that drives the cone) exceed normal speakers by a factor of two or three to one. Lowthers produce flux densities as high as 24,000 gauss--an astonishing number if you compare it with normal speakers.

4. Lowthers use the thinnest and lightest cones in the world. This can be a problem with 'normal' speakers, but Lowther uses a special ribbing to reinforce the cone in the direction of travel. Additionally, Lowther uses rolled paper which is cut and bonded, rather than 'pressed cones.' It is impossible to maintain a uniform thickness with 'pressed cones'. Lowther's technique insures absolute uniformity in the cone. The thin, almost weightless cone material, in conjunction with the enormous magnetic field, allows Lowthers to respond instantaneously to the changes in the music.

5. Lowther uses a patented voice coil technology called 'Hi-Ferric'. The wire of the voice coil is an alloy of ferric materials including cobalt, iron and nickel. When electricity passes through it, it becomes an electromagnet in its own right. When it is placed within the voice coil gap, it perfectly aligns itself. On receiving an electrical signal, the coil will either accelerate away from, or be attracted to, the host magnet, depending on the polarity of the applied signal. This results in a much quicker reaction than normal speakers, a more accurate representation of the musical signal, and far less distortion. Coil oscillations are virtually eliminated, damping is greatly increased, and separation of the various instruments and voices is greatly enhanced.

6. Lowthers are among the most efficient speakers ever created. All Lowther 8 inch speakers produce at least 102dB from one watt--at one meter--in a bass reflex cabinet. Some are even more efficient. Very few other speakers are capable of this performance--and then only the largest bass horn designs.

7. Lowther-Voigt has been in business for more than 70 years.


Lowther Speakers--Some Myths

As with any product that has been made for many years, there are a lot of myths surrounding Lowthers. Let's take a minute to address some of these:

1. Lowthers only work well with low powered tube amps.

Nonsense! Lowthers work well with tube or solid state, low power or high power. A great amplifier is a great amplifier. It doesn't matter whether it uses vacuum tubes or solid state devices.

And the power rating of an amplifier makes absolutely no difference, as long as it isn't 'clipping' (running out of power). A speaker can't tell how powerful the amplifier driving it is. If the speaker is using 1 watt, it doesn't know whether the amplifier driving it has one watt in reserve or 1000. In fact, Lowthers actually make high powered solid state amps better. How? Because most of these amps run pure Class A for the first two or three watts--all you will ever need with Lowthers.

It is true that Lowthers work better with low powered tube amps than any other speaker. This is because no other speaker is as efficient. You will get full, rich sound, at normal volume levels, simply because they are one of the very few speakers with high enough efficiency so you will have enough power to drive them.

Another reason that Lowthers have been linked to tube amps is that most tube amps (especially modern ones) are very soft and warm sounding. Most modern speakers are the same. The combination will just put you to sleep. Only the great detail, clarity, and realism of Lowthers will bring out the best in these amps.

2. Because of their design, Lowthers only work well in 'bass horn' cabinets.

Again, nonsense! Modern Lowthers work superbly in bass reflex cabinets. The factory offers more than 7 different bass reflex designs for Lowther speakers.

3. No full-range speaker can really go to 20,000 cycles--that's why they invented tweeters.

It's not true. One listen and you'll wonder why anyone builds tweeters.

4. Lowthers don't have enough bass.

Absolutely not true. In fact, Lowthers have the tightest, most accurate, and most realistic bass of any speaker. In addition, they test down only 3 or 4dB at 40 cycles in a good bass reflex cabinet. It's true they won't produce enormous sound pressure levels--after all, it is only an 8 inch speaker. However, the bass they produce is balanced and totally satisfying with well recorded material. Modern bass reflex cabinets are capable of astonishing levels of deep, full, rich bass. You can actually feel the pressure on your chest--not just hear the bass.

Of course, this is only possible with an amplifier with flat response. The myth of poor bass probably comes from many owners using poorly designed low powered single-ended triode amps with a rolled off response. However, many new single ended designs are capable of producing excellent bass. For those that don't, a quality subwoofer is the answer.

5. Lowthers are overly bright.

Lowthers are accurate. They can only play what they are given. If you play poor material, it will sound poor. If you play the best material, it will sound like heaven. As they say, 'junk in, junk out.'

6. Lowthers are fragile and there are quality control problems.

Absolutely untrue. It may have been so many years ago, but no longer. Quality control is as good as any speaker made today. There is an unconditional two year warranty against original manufacturing defects.


Model Range

Now let's talk about the different models that are available:

Lowthers come in two frame sizes--8 inch and 6 inch. Both are made using cast aluminum frames of massive proportions and strength.

The smaller 6 inch Lowthers, though often referred to as 'midrange' units, are really full-range. They do not need crossovers and will play down to 80 Hz (as opposed to 30 Hz for the larger speakers). They can, however, be used as 'midrange' upgrades for other brands of speakers. They can also be used successfully in mini-monitors. They blend well with subwoofers. The smaller Lowthers use magnets of extraordinary size. But the question remains--why choose the smaller speaker when the larger 8 inch offers much more bass and the same high frequency extension? I believe that in former years, the 8 inch speakers probably did not have the same high frequency extension. But there really seems little use for the six inch speakers today--especially considering that they cost the same as the 8 inch models.

Moving on to the eights.......there are three Lowther 8 inch models that use Ceramic/Ferrite magnets (identified with the suffix 'C'), five Lowther 8 inch models with Alnico magnets (identified with the suffix 'A'), and six 8 inch models that use rare earth Neodymium magnets (designated by the prefix 'DX' or 'EX'). All use the same frames. The main differences are increasing magnet strength (with cost) and variations in voice coil design. The Alnico and Neodymium magnet types can also be identified by having tan colored cones while the ceramic/ferrite cones are white. In addition, the two cones use a different ribbing pattern.

The Neodymium speakers are divided into two types--the DX series and the EX series. The DX series uses the same 'bullet' shaped phase plug and open back as the Ferrite and Alnico speakers. The EX series uses a different phase plug and has an aluminum 'module' or 'can' attached to the back. This new design is aimed at bass horn cabinets.

The two different features of the EX series work as follows:

First, the 'module' or 'can' on the back of the speaker is filled with foam material. This foam material absorbs the mid and high frequencies emanating from the BACK of the speaker. Remember that a speaker will radiate sound from the front AND the back. In a bass reflex cabinet, there is acoustic damping material fitted to the cabinet to absorb the sound coming from the back of the speaker. In a bass horn cabinet, it is not possible to fit damping material to the cabinet. It would interfere with the bass waves going through the bass horn. Without damping material, these mid and high frequencies hit the back of the wood chamber behind the speaker, and reflect back to the cone and introduce distortion and cancellation of sound. This has always been a serious problem with bass horn designs. This 'module' or 'can' is the factory's solution to this problem.

The second new feature of the EX series is the unusual phase plug called a 'phase equalizer.'. This was designed specifically to balance the pressure the acoustic chamber applies to the rear of the cone.

We did extensive testing of the EX series of speakers. We compared them with the comparable DX series speaker (EX3 versus DX3, for example). Our testing revealed that the EX series of speakers had increased output in the upper midrange and lower treble. There was reduced output in the lower midrange and upper bass. The result is that the EX series can be best in some bass horn cabinets, but never in bass reflex. But in many bass horn cabinets, the DX series is still preferred.

We also experimented with the new phase plug. In a bass reflex cabinet, we prefered the presentation of the older 'bullet' phase plug. However, we are prepared to accept the factory's assertion that the 'phase equalizer' is an improvement in some bass horn designs.

The bottom line here is that the EX series did not improve the sound in bass reflex cabinets. The added output in the upper midrange and lower treble tended to make bass reflex cabinets overly bright. We also prefered the dispersion pattern of the older phase plug. Coincidentally, bass output for both the DX series and EX series--in bass reflex cabinets-was essentially the same.

PM2C


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