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Revolutionizing the market - Lehle Components

May 08, 2020

German engineer Burkhard Lehle unveiled his plans for the Lehle Components a few years ago at the NAMM show. He would release his own line of audio components, which would include brand-new designs alongside his older inventions. A new switch would be the demise of the old-style, unreliable footswitch. It took a while, but when Lehle finally introduced their Lehle BTN-switch, it was an easy replacement for any regular momentary footswitch and became an instant hit!


IN THE PAST, momentary switches were mainly used as tap tempo-switches or in programmable bypass loopers, but these days they are also widely used as bypass-switches in relay-switched effect pedals. We’re talking about such effects, as – for example – all Strymon pedals, or Walrus Audio’s two-switch effects, such as the Slö and the ARP-87.


We have been replacing regular switches with the Lehle BTN's for some time already. Typical cases are true bypass -switchers, which often see a lot of action on pedalboards. This modification was made to Mikko Von Hertzen, just before the Kingston Wall by JJylli, Kuoppis & VHB  -shows in 2019.


As the name says, in a momentary switch the switching contacts only touch each other while the switch is pressed down. The contacts are released the instant the foot is taken off of the pedal.

The main advantage of momentary switches is that they work smoothly and quietly, without causing any audible clicking noises. You can easily spot a momentary switch, because most of them have only two soldering tags.

Lehle Module SW

Lehle recently introduced their eagerly anticipated Module SW -relay module, which enables you to replace noisy 3PDT-switches with a Lehle Switch BTN-switch.

The Module SW is a little smaller than a nine volt battery, making it easy to install inside a pedal’s battery compartment with 3M Dual Lock or Velcro.

One of the module’s best features is that it’s programmable: in addition to regular on and off switching, you can also use the module for momentary switching action. You can also program it, so that one short push will turn the effect on and one short push will turn it off, while keeping the switch down will turn the effect on, and releasing the switch will turn the effect off again.

Case: Anssi Kela and the Electro-Harmonix Synth9

Shortly after we had received our first shipment of the Lehle module, we were faced with a job, where we could make good use of it. Finnish hit-making singer-songwriter Anssi Kela was in preproduction for his series of intimate biographical acoustic shows.

We had already built Anssi a dedicated pedalboard for use with his acoustic guitar; the board included a tuner, an outboard preamplifier for his guitar’s pickup system, an EQ, and a Lehle Acouswitch IQ DI-box. Because the new shows were to feature only the man and his guitar, he required a few additional “spices” in his signal chain, which is why we added a Boomerang audio looper, Walrus Audio’s brilliant Slö pedal, as well as an Electro-Harmonix Synth9 guitar synthesizer.


There was one problem with the synth, though – each time the built-in switch was used, there was a discernible mechanical clicking noise. In band use, such a click would be drowned out by the other instruments, but in an intimate acoustic gig this noise was unacceptable. The worst case scenario would be if, during live audio looping, one of these clicks would end up being recorded as part of the loop. This looked like a good acid test for the new Lehle module.


We started by opening the pedal up, and by using a multimeter to check the original switch’s polarity. We faced our first little problem: this was a buffered effect pedal, meaning that the switch was wired differently, compared to a standard true bypass-circuit. Mechanically, though, this was a regular 3PDT-switch, which meant that we would, in all likelihood, be able to make use of the module, even if we would have to get a little creative.

We unscrewed the original switch and unsoldered the flat cable that connected it to the main circuit board. We installed the Lehle Switch BTN-switch and connected it to the corresponding cables of the Module SW. Then we soldered the module’s power cables to the effect’s DC-connector.

This was the easy part, but now we stepped into uncharted territory. We had to proceed making educated guesses and using trial and error. After a few steps we managed to get the pedal up and running, but there was still a nasty pop, each time the effect was turned on.

At first we suspected that there must be some DC leakage into the circuit, which we tried to filter out with some capacitors and resistors. We soon found out, however, that the problem was caused by something else, and none of our added components made any clear difference.



Because the actual switching of this effect happens on the circuit board itself, and not inside the switch, we started taking a much closer look at the original switch. We had to find out how the old switch was meant to work in the pedal, and we had to do it without a circuit diagram.

We could brag and boast that we had a sudden flash of genius that made us realize how the circuit had been meant to work. In reality, though, we had to try systematically several possible wiring options, before we got it right. The effect now could be turned on and off perfectly quietly, which was our main objective. But, alas, our problems weren’t over yet. Now the indicator LED was switched on all the time.


Our solution was to remove the LED from the circuit board, glue it in place in the pedal’s casing, and then solder the module’s cables directly to the light’s contacts. Now everything worked! The effect switched on and off in dead silence, and the LED, too, lit up and went out correctly.

 

Our first use of the new Lehle products was a little bit hit-and-miss, but the end result was fantastic to witness in this type of pedal. In view of the intimacy of the show, the quiet switching action proved really very important.

As the world is full of equipment that are only copies of copies of copies, with most brands simply taking readily available parts and throwing them together to make up their “own” designs and products, we felt we were at the threshold of a new era.



Revolutionizing the market

Before Lehle's original innovations, American ABY-switchers in the Nineties were full of bugs and problems. The three most common complaints were:

  1. The switcher units either had no indicator lights at all or were equipped with underpowered lights, leaving the user literally in the dark.
  2. Buzz and hum were prevalent, due to incompetent design and/or badly selected components.
  3. The footswitches were very noisy and fragile.

Of these problems, the last one seemed to be the most irritating and pressing, which is why Lehle chose to solve it first. One of the most idiosyncratic features of a classic Lehle-switchers is its psychedelic-looking mushroom-shaped footswitch. Lehle has been using this type of switch for over a decade now, and it has always intrigued us.

We found ourselves wondering whether Lehle has made the same type of compromises in the quality of his products many of his competitors have fallen victim to. Many companies start off with a killer product, which brings them fame and a flood of orders. Then they switch to cheaper production methods, in order to make a larger profit, sacrificing quality in the way.

We are struck by the fact that both units are virtually identical, despite their ten-year age difference. A decade is an eternity, when it comes to component lifetime and production techniques. We give a close look at the psychedelic mushroom-switches on both units, looking at all the small print and the model designations. It’s the same labeling! It must be the same switch!

We try to get a glimpse of the inner workings of the switch. How on earth is it possible that this switch can take over ten years of abuse? Just looking at it I can tell that, mechanically, this switch is quite different from your run-of-the-mill stompbox switch. The switch itself isn’t in direct mechanical contact with the mushroom-shaped top, but rather coupled via a spring-loaded mechanism. The mushroom-shaped part of the assembly is attached to the switcher’s casing, keeping the full force of your stomping foot from reaching the circuit board.


 

Failing switches 

In an interview Mr. Lehle once asked: “What’s the use of an amp switcher that’s unreliable?” Traditional ABY-switchers are equipped with a switch that has a projected lifetime of approximately 10,000 switching actions. These switches are prone to mechanical failure, and they have been designed originally for use with much higher voltages. It only takes a grain of sand or a bit of dust for such a switch to fail or stutter. The result is a lot of noise, most often heard as a loud bang or a scratchy signal.

A discovery at a trade fair

In 1999, Burkhard Lehle came across a strange new type of switch at a Munich trade fair. The switch had a large aluminium pedal part with moving plastic bearings. These bearings were in term connected to a separate switching unit, which was protected by its own housing. This was the way most switches have been working in industrial applications – by indirect coupling. The manufacturer of the switch Lehle saw at that fair promised a minimum lifetime of two million (!) switching actions!

Burkhard Lehle saw this switch as the solution to his most pressing problem. He started to develop a version of this type of indirect switch for use in his own products. 


 

A European invasion

The first switchers utilizing this new type of switch were introduced around the turn of the millenium. When they came out in 2001, Lehle’s units were like something from outer space: They revolutionized the concept of what a professional-quality ABY-switcher should be. Lehle left nothing to chance. Each component is the best quality available, and the design of the switcher boxes leaves the signal uncoloured and free from extraneous noise.

Due to their European origins, Lehle’s boxes also looked different. Lehle used German designers to come up with his company’s casings, while his competitors mostly stuck to off-the-shelf effect housings.

But Burkhard Lehle didn’t rest on his laurels, introducing an even smaller switcher model a few years later. The aluminum top still looked like a mushroom, but the actual switch was a different, new design employing a top-of-the-line internal slider switch inside the unit. The newer switch is guaranteed to work one hundred thousand times, and both designs are still used in brand-new Lehles to this day. It sounds kind of macabre, but there is the real possibility here that a Lehle-switcher will outlive its original owner.

After coming up with a clever solution to the problem with traditional footswitches, Lehle had to tackle the other issues as well.

Lehle LTHZ isolation transformer

Isolation transformer breaks the actual physical contact between the guitar and the amp, while transporting the audio signal onward with the help of electrical induction.

The straight physical contact between the guitar and the amp is broken, but the audio signal is transported unscathed through the transformer using electromagnetic induction. Breaking the physical, electrical contact between the guitar and the amp also breaks the ground loop. An isolation transformer has an amplification ratio of 1:1, meaning that the transformer is meant to keep the outgoing signal level identical to the incoming signal level. Because a guitar signal is very low-powered, an isolation transformer has to be extremely well made to ensure the signal doesn’t deteriorate. The weaker the signal the more difficult it is to keep it clean and uncoloured. 

Off-the-shelf transformers aren’t good enough

Most bulk-produced transformers have a tendency to shift the signal’s mid-frequency emphasis slightly downward. Because the mid-range is where all the important information is in a guitar signal, this mid-shift sounds like treble attenuation to most of us. A preamplified guitar signal (or using active pickups) will not suffer from this mid-shift phenomenon, but a regular passive electric guitar (especially one with singlecoil pickups) needs a more sensitive, high-quality transformer for effective ground loop defeat without signal deterioration.


 

How did Lehle solve this issue?

At the beginning of his career, Lehle had to make do with the same off-the-shelf transformers as everybody else. Like the other manufacturers, Lehle, too, had to circumnavigate the known frequency problems. One way is by using a built-in active preamp or buffer amp to pump up the signal level internally, allowing the designer to employ standard audio transformers. The downside to using an internal preamp is that, while such a switcher box successfully does away with hum and phase cancellation problems, it also has an impact on the sound and playing feel. The interaction between guitar and amp is changed, and the signal’s dynamic range is compressed.

Lehle comes up with his own transformer design

Lehle soon got fed up with OEM-transformers, and set about to come up with his own, improved transformer design. He started from scratch and the development took him two years. The result is an isolation transformer that breaks the ground connection, while keeping all of the guitar signal intact. This transformer allows for the natural interplay between a guitar and an amplifier.

Lehle’s legendary LTHZ-transformer makes sure all of the information contained in the guitar signal is kept intact and unchanged. With a singlecoil guitar you will notice this in the brilliant top end and the natural cluck in the attack. Humbuckers won’t mush up, which is especially noticeable on clean settings. You can say without exaggeration that this is the best isolation transformer for guitar use in the world. Now he only had to find a (simple) solution to the most annoying practical problem.

A magnifier for the LEDs

It’s a real pain in the proverbial, when you’re having to switch amp configurations mid-gig without any visual clue to what you’re really doing. Did I press the footswitch, or not? The underpowered LEDs on old switchers didn’t really help you that much. Many guitarists complained about this issue, which is why Lehle installed magnifying lenses on top of his indicator LEDs. This made it easy to see your switcher settings, even through the mists of loads of artificial fog from the smoke machine.

Different switching modes are indicated by differently coloured LEDs. This really isn’t rocket science, but many other manufacturers simply didn’t care about the real-world onstage problems gigging guitarists are facing. For Lehle this little improvement was the icing on his cake.

IT IS INTERESTING to see what Burkhard Lehle will come up next. This man has revolutionized a whole branch of the audio industry, so I can’t see why he shouldn’t be able to do it once more. Maybe other brands could also benefit from Lehle´s innovations?


View Lehle Products


9.5.2020 Eetu Lehtinen and Kimmo Aroluoma

Eetu Lehtinen is Custom Boards’ pedalboard technician and a gifted craftsman, who is in charge of wiring up our boards. In his spare time Eetu plays the bass guitar in the bands Demonic Death Judge, ssSHEENSss and Burweed.

Kimmo Aroluoma is the owner of Custom Boards Finland. He is a veteran guitar tech who has toured for years with Finnish bands HIM, Amorphis, Michael Monroe, The Rasmus and Von Hertzen Brothers. Today he designs pedalboards and runs his own web shop in Helsinki, Finland.

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