Category Archives: DEVELOPMENT

About DryBell Module 4


… technical stuff, challenges, development and more

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Dear friend,
If you are one of those people who likes to read more about the product you are interested in, you will find some cool stuff about the Module 4 development in this article. We will talk a little bit about DryBell’s last two years, some technical details, how the DryBell team got this idea and what exactly the Module 4 is all about!


DryBell’s retrospective of the last two years

It was the end of November 2020 when we rented more space in the same building and started moving into our new extended workshop. At the same time Kristijan – Kiki, another development engineer, joined us and he started working on the development of a new pedal with our team. So, Martina and Zvonch had to move out from the common space and main workshop where they were sharing room with Marko and Luka and move into the new space with Kiki. That way Marko and Luka got a lot more space for production, packing and order shipping. We’ve invested significant funds into this expansion of DryBell, but none of it would be possible without you, our faithful customers, who have never stopped supporting us, even during the first year of the pandemic. Thank you all!


In the pre-holiday season of 2020, even though we still hadn’t fully arranged the space and moved completely, Zvonch and Kiki had already started purchasing additional measuring equipment for Kiki’s new work space. Acquaintances from gigging days both were crazy excited about the following development period. At the same time, Martina was pretty occupied with handling the customers’ and dealers’ orders and a lot of office work, while Marko, Luka and Zvonch were diligently arranging and setting up the new DryBell premises. We also had to rent an additional small warehouse in the same building. Depending on the situation and needs, we might need even more space soon.



Due to the global electronic components shortage and supply disruption, we have also struggled with our stock supply. Prices have increased significantly and lead times extended often to more than a year. It was very challenging to stay in line with our production plans and it still is, but the DryBell magic never stopped.


At that time, Kruno’s initial idea for a new pedal, that we had been working on for some time, was quite a bit different than a stand-alone compressor. We generally develop initial or existing ideas for pedals as a team until we find a solution that we are all fully satisfied with. For example, we already have the initial idea for the next pedal. Will the final idea be identical to the one we imagined at the start? We don’t know that yet. After a few months of development there’s a chance that we modify the idea quite a bit, which could eventually morph into a completely new shape at the end. Kruno is a master at initial ideas because he has been personally and professionally engaged in researching the sound of guitars, amplifiers and pedals and the history of rock & roll almost his whole life, and he constantly gigs with his band. He used the Orange Squeezer throughout his career, and now he is using it again in the fantastic new form of the Module 4. Kruno plays in one of the most famous Croatian rock bands, ‘Majke’, which has been active on the music scene since 1984. Also, in the pre-pandemic year of 2019, Kruno won the ‘Status’ award from the Croatian Music Union in the category of best rock guitarist. The on stage Module 4 tests were great and very useful as always.


Kiki, our new engineer, also actively plays in a band (he started playing the guitar in 1999), so apart from his outstanding engineering skills and experience, he is a strong reinforcement to our team for testing pedals live on stage.



When we finally moved to our new space, Marko and Luka got back to pedal assembly. During the early part of 2021 we had already been feeling the increase in prices and the pressure of component shortages, but we decided not to raise the prices of our products at that time. Marko and Martina dealt with the challenges of procuring components so that Marko could organize complete production. Besides assembling tasks along with Marko, Luka sonically tested every pedal produced in the workshop. With Kiki in the team, the time needed to develop and release new pedals will become shorter, but the pedals also have to be produced :). A good organization of production and all the extra work that must be done wouldn’t be possible without Marko and Luka, our ‘kings of assembling and magicians of production’!


DryBell is a small company. Apart from the huge amount of work that is done in our company’s workshop in the town of Krapina, we also have partners with whom we have been cooperating with for years. There were some partners we had to end cooperation with because we were simply not compatible, whilst have extremely respectful and excellent cooperation with all the others. E.g. the same company from Zagreb has been doing SMD assembly for us since 2010. Jasmin, our local screen-printing guy has been working with us since the very first Vibe Machine V-1 enclosure. Zlatko Horvat, Zvonch’s former colleague from Končar has been doing complete THT soldering of DryBell pedals for the last few years. Zvonch says that in his entire life he has never met a person who is as skilled at hand soldering electronic modules as Zlatko. Our entire team, friends and partners always have a good time at the collective gathering that we regularly organize after each new pedal release (DryBell team building).



In the fall of 2021, as a way of celebrating our 10 year anniversary, we released a new version of the Vibe Machine, the blue V-3, a bit different from its predecessors. We’re very proud of this development and of the whole Vibe Machine series; we see you are satisfied too, which makes us very happy.


When the Vibe Machine V-3 hit the market, our 4th pedal – Module 4, was already deep in development thanks to our new engineer Kiki. Although Zvonch and Kiki worked as a team on both the Vibe Machine V-3 and Module 4 projects, in the early spring of 2021 Zvonch was more focused on the development of the V-3, while Kiki was more focused on Module 4 circuits. So the guys worked on two projects in parallel for about 8 months.


In 2021, we also started our DryBell Sonic Experience YouTube demo series. The idea behind it is to feature some of our favorite stompboxes from a vast sea of incredible effects working in synergy with our pedals. Each DryBell Sonic Experience episode is played and produced by Kruno. He lives in Zagreb and works from his home studio. Kruno is one hour drive from us, so he often joins us in Krapina. We always test things together and work as a team on other DryBell stuff.



2021 was behind us. At the beginning of 2022, our Module 4 prototype design was in its final phase and our preparations for the NAMM 2022 show in June had already begun. Martina had a lot of work to do with the preparations for the NAMM show and the logistics of the entire trip to the USA. In the same period, Zvonch was working intensively on the new enclosure design construction and he joined Kiki in the electronics design work a bit later. Their joint work created a very strong synergy. As a result amazing R&D work was done.


In June 2022, Martina, Zvonch, Kruno, Kiki and Tom Cundall, our dear friend and colleague from London, traveled to California for the NAMM show. It was Kiki’s first NAMM and he fitted in perfectly to our existing NAMM crew. NAMM 2022 was a smaller show compared to past years, but it was an amazing experience once again. One of the most impressive moments from our California trip was a Michael Landau concert in The Baked Potato, Hollywood, LA. We had the great honor of meeting and talking to Michael after the concert. He bought our Vibe Machine back in 2015 and it has been on his pedalboard ever since. What an incredible person and a gentleman he is!
Tom Cundall has been our friend since 2012, when his lovely wife Maddy bought him a Vibe Machine V-1 as an engagement present. He was delighted with it. That’s when love and true friendship was born between us, as if we knew each other from another life. Besides working for us at the NAMM shows as a presenter, Tom has become an important member of our team as a beta tester of our new pedals, creative advisor and editor for our web content, and he also appears in our latest demos.


DryBell’s presentation at the NAMM show went great and our visitors were more than thrilled with the Module 4’s concept and sounds. The new Vibe Machine version (V-3) also received many compliments, along with the Unit67 and The Engine. All the feedback we received at the show gave us lots of confidence in our new product and also into the entire DryBell pedal line. High quality products and truly unique, well-thought-out designs have been our trademark since the very beginning, and we’re glad that our customers recognize it. We will do our absolute best to continue along this path.




We returned happy from our US trip and went on our usual summer vacation soon after, taking a break before getting back into the action of all the final prep work for the Module 4 release in the fall.


With every new product, especially those that require a lot of new technical and design solutions, there are always smaller or bigger challenges to overcome. We were 4 weeks behind our planned release date but that didn’t matter anymore. In August, September and October 2022, Zvonch, Kiki, Marko and Luka were pretty occupied with the development and improvement of various testing procedures and production processes. The electronics’ test procedure was improved and additionally automated in cooperation with our external collaborator Mario. All of the guys did an amazing job here. During those last couple of weeks of intense work by the whole team, we were all excitedly waiting for the release date.


In the meantime, Kruno went to London to film a DryBell Sonic Experience Module 4 demo episode with Tom. Meanwhile, Marko and Luka were diligently soldering parts, preparing housings, doing tests of electronics modules, assembly, sonic tests and final packing of each and every Module 4 for the first production batch. It really took a lot of effort to make everything work as we imagined and we are extremely satisfied with how everything has turned out.





Finally, Zvonch, Martina, Kruno and Kiki, in cooperation with Tom, prepared all of this hopefully interesting material about the Module 4. Everything we wanted to tell you and show you about the pedal is here, on our web site. We also learned quite a few things along the way.


What can we conclude at the end of this introduction? Well, we’ve put all our energy, knowledge, skills and experience into this new pedal again. It’s hard to describe the level of happiness when you finish such a big project. We hope you’re going to like the Module 4 as much as we do. For those who are interested in the technical stuff, you can find out how the Module 4 actually works in the following sections of our article.


The DryBell Module 4 is released on October, 28 2022.


Module 4 Technical Story

Goals and ideas behind the Module 4

Our initial idea for the pedal was not a fully-featured compressor with the classic controls. It was a pedal that would have a simple one knob compressor in its design, as one of its features. But when we built the Orange Squeezer (OS) prototype with ATTACK, RELEASE, RATIO and PREAMP controls, we were blown away by how well it worked on a variety of guitars.


Considering that we set ourselves the goal of lowering the noise floor as one of the basic requirements of our compressor part, a lot of development time had already been spent on that task. Being very satisfied with the results and versatility so far, we changed direction and decided to create a fully adjustable compressor with this Orange Squeezer’s iconic character. A mitigating circumstance was that we hadn’t even started working on the other parts of our pedal anyway; we only had this first breadboard compressor prototype at that moment.


However, even though our prototype had all the standard controls, we still had challenges. At first, our prototype didn’t sound 100% like the Orange Squeezer. After further research, we found that the last missing and very important detail was the influence of the dynamic input impedance. When we solved that challenge, we got that legendary original character we were looking for. Finally, our Module 4 breadboard prototype faithfully provided all the tonal flavors of the original design. We still had the task of developing secondary features, so the unit can satisfy almost every user. That was our goal.


All features

By deciding to make a fully featured OS version, we automatically set ourselves several more goals. We decided to add TONE and BLEND controls. Using a BLEND control, a parallel compression is applied. In practice, it’s also a sort of Ratio control for the desired compression character. However, we decided to give the user a switchable option for a JFET compressor too, without that classic Orange Squeezer’s EQ character (described further in the article). In this way, the user actually gets two types of compression in one pedal. You just need to turn off the ORANGE button. We call this mode ‘Full Frequency range’. It’s the same thing as putting a buffer in front of the original unit.


We wanted the compressor to have a visual indication of compression and different bypass options. We also made the pedal to work as a versatile first-in-the-chain BUFFER. Furthermore, during the second phase of its development process, we decided to add an Expander feature. Additionally, we designed a LOW END cut option because the original circuit can sound clearer with a bit of reduced low end when used either clean or with drive pedals. But, the user can always turn off that feature and get the original OS low end response, which is a very important part of the original OS’s tonal character.


During development, we also thought about the operating temperature. That was a huge task; we made a pedal that works from -15°C/5°F to 70°C/158°F and does not change its sound characteristics in that wide temperature range. Why did we do it? We wanted to achieve studio quality and road durability/reliability.

Armstrong’s magic

We thought about a lot of things. It is impossible to describe everything here because this article really would be too long. It’s already long enough 🙂. But, when you see, feel and hear it, you will know why the Module 4 is a very special piece of gear!


In the next section we will talk technical stuff and why we have to give our gratitude to the late Dan Armstrong.



The Orange Squeezer tonal analysis:

Why its unique feel and tone can only be heard if you’re not using active pickups or any type of buffer in front.


As we have already said, the Module 4 is a highly versatile compressor inspired by the vintage Orange Squeezer. When we say versatile, we say it for several key reasons. But first, we have to explain why the OS is such a special and unique sounding compressor.


The main purpose of the OS circuit is compression of course, but this circuit does not only compress the signal. Another important fact is that simultaneously with compression, the OS dynamically changes the EQ. In comparison to the EQ when the guitar is connected directly to the 1MΩ amplifier’s input, the top end is attenuated and the mids are slightly shifted to the lower frequencies. But this matter is not so simple.


An interesting fact is that this EQ change or shifting is not fixed or constant. It’s not a fixed EQ like when you take an EQ pedal and set some tone settings that suit you. Furthermore, this is definitely not a classic phenomenon with compressors where the sonic characteristics (most often top end) are changed under the influence of attack and release settings. It’s a real variable EQ, applied before compression, and it reacts and depends on two specific things.


Firstly, it reacts to the pick attack dynamic (hard or soft playing style etc.), and secondly, it depends on the type of guitar used (pickup type). That dynamic EQ change happens because of the way the original circuit is constructed. We are talking here about the variable, signal-intensity-dependent input impedance of the circuit. Also, it’s relatively low impedance. This variable EQ is only the first part of the whole OS signal processing; the OS tone mechanism has additional things going on. The following consideration in the next section may only be for those who are interested or have a little basic knowledge of electrical engineering.



The envelope followed EQ

We will try to explain OS tone through a well-known example. As we know, when we connect a guitar to a HIGH versus LOW impedance input of a classic amp (i.e. Fender Deluxe Reverb), we get two pretty different EQ responses (let’s put the volume difference aside for now). Those two EQ characters depend on the impedance of each amp’s inputs and on the type of pickup used (its inductance mostly, but cable capacitance, tone cap value, guitar pot resistance, all have an influence on the tone).


Now, imagine you have a smooth fade operation between those two EQs of HIGH and LOW input connections. And this EQ fade operation is controlled by your pick attack. That’s exactly what the Orange Squeezer does!


Furthermore, we can say that this impedance change (or ‘EQ fade’ or dynamic equalization, however you want to call it) AND automatic gain (compression) happens simultaneously. Basically, the same seemingly simple circuit in the OS does both. But, when the guitar is connected directly to the OS input, electrically speaking, the pickup only sees this variable input impedance; the compression is shaped “later” in the chain. The guitar signal ‘doesn’t know’ that it will be compressed, but the interaction between the guitar pickup and the variable input impedance appears regardless.


Now we need to concentrate 🙂 . Since this dynamic input impedance is a result of dynamic reaction of the compressor circuit and the compressor reaction is a result of pick attack, the ‘EQ fade effect’ reaction depends on the pick attack too. In other words, when connected directly to the guitar (pickup), the OS unit acts like a kind of envelope followed EQ.


This impedance change is not huge, typically somewhere between 80kΩ and 200kΩ (extremes), but that EQ response can be heard and felt and it is VERY pleasant. It’s also totally different compared to the guitar connected to any fixed impedance input. We did numerous listening tests (and blind tests later) between fixed and dynamic input impedance, and there is no doubt, the dynamic input impedance is something that gives the Orange Squeezer its character.


That’s one of the essential reasons why the Orange Squeezer is such a specific and unique compressor. Its circuit is very simple, but its impact on the guitar’s tone is far from it. We have a lot of respect for Dan Armstrong’s circuit. Many other simple designs from pedal history deserve huge respect. In those days, it was not easy to do.


Orange Squeezer’s compression characteristics

The second part of the OS character is its spongy organic compression. Yet another great feature of the OS is the ability of stacking with different drive pedals. If used in moderate drive settings, the long sustain and multiple harmonics would evolve in note bloom resulting in beautiful feedback.


When playing the original unit using different types of guitars, you would notice that with different pickups, the OS responds with different amounts of compression. With hot pickups, you may get too much of a compressed signal and a completely opposite result with low output pickups. It also depends on your playing style. This is the result of the fixed gain of the original unit and its internal bias settings. This is why we have added the PREAMP control to the Module 4.


Also, the fixed attack and release settings of the original unit are not always favorable for every style of playing or all types of pickups. All of these fixed settings are the reason why some guitarists simply like or dislike the original unit. That’s why we made a prototype with all compression controls immediately at the beginning of development. For example, Kruno says that for his playing style, the Orange Squeezer was almost unusable with humbuckers. With additional controls, Module 4 adapts to any instrument or playing style, and at the same time retains that original pleasant tone and character. Having said all that, we can conclude that Module 4 is a very versatile take on the OS.





The Module 4’s internal signal path description

Over the next few sections we will focus on the more advanced and technical parts of the Module 4. For easier understanding of how the Module 4 works, here is a simplified block diagram of the Module 4’s internal design. We’ll try to explain every stage/feature separately.




The guitar input signal goes firstly into our new bypass system. The user can choose between true and buffered bypass OR buffered bypass with the pedal’s Front-end circuit activated. You can read more about those bypass benefits later in this article.


After the bypass routing system, the signal is sent to the analog Front-end circuit. The Front-end circuit automatically controls the input impedance – it does it in real time as the compressor works, because the compressor sends a control signal to the Front-end. That Front-end circuit operation can be disabled with the ORANGE button, in which case the compressor becomes a JFET compressor without EQ coloring (we have named it ‘Full Frequency range’ compressor).


An ultra linear and low noise, high bandwidth buffer with a high headroom of 13.5Vpp (15.8dBu) prepares the signal for the PREAMP stage and BLEND control, OR for buffered bypass – if the pedal is in buffered bypass.


The PREAMP stage allows the user to set the gain of the signal, so different levels of compression can be chosen for different instruments or playing styles. Gain can be adjusted between -15dB to +11dB.


After our ultra-low noise compressor stage (described further in the article), the signal is passed to the parallel compression circuit (BLEND) and sent further through to the TONE and Output Booster (make-up gain) stages. The compressor stage also controls the Front-end circuit impedance in real time.


The EXPANDER operation and LOW END cut filtering are performed in the compressor circuit itself and these analog functions are controlled by the microcontroller.


In the next section we will describe the working concept of the Module 4 circuitry.


The challenge of lowering the noise floor

If you have read our main Module 4 description on our product page, you might have noticed that we said that we lowered the noise floor by more than 10dB compared to the original OS design. Even with the TONE control added. This is a huge improvement. The noise measurement shown below is the noise floor at the optimum bias settings and with the identical sonic response. You can read more about optimum bias settings in Kiki’s OS circuit letter. So, we actually did it, but the question is how?


With our Unit67, and later with The Engine, we started designing our circuits as high-current-low-noise in signal paths where needed. The same was applied to the Module 4. Some may know this, but lowering circuit’s resistance is a powerful way to achieve low noise floor. Certain audio and guitar pedal manufacturers have already used this technique for years as standard.


The compressor system in the original OS uses the principle of an automatic potentiometer with a (relatively) high ‘taper’ resistance. This is done with a well-known and widely used JFET transistor circuit, where the resistance of the JFET transistor is voltage controlled. Because the transistor in the OS circuit has relatively high resistance, it can be very noisy in certain bias settings. Remember, in the section about input impedance interaction with pickups, we said that the same OS circuit stage controls dynamic EQ response and compression simultaneously. But, for the compressor to work in the same way, it doesn’t have to be constructed like the original OS circuit!


Solution with two separate stages

So we have divided these two functions (input equalization and compression) into two separate stages. The Front-end circuit in the Module 4 is responsible for dynamic input impedance and gives the ORANGE character to the Module 4. The compressor stage is designed separately with a very low resistance, so it can have an ultra-low noise floor. To our knowledge, this is the first such redesign of the Orange Squeezer in the world. All of the Module 4’s circuitry is completely original and unique in its design, we made it just the way we like it. Are we the first to make such a take on the Orange Squeezer, with the described operation and circuitry? You tell us.


Furthermore, with such a separate Front-end circuit, another of our goals was achieved, which was that the Module 4 can work as a JFET ‘Full Range’ compressor. In this case, the Front-end circuit is switched off; this simply means that the ORANGE mode is off.


These are still not all of the advantages. In the following bypass paragraphs we’ll explain why it’s great for the pedal’s usability to have a separate Front-end circuit. It’s all about the impedance game 🙂



How quiet or loud can bypass operation be?

The new bypass system was a big challenge and a lot of development time was spent on this. We wanted to make the bypass as quiet as technically possible. At one point we bought several types of different switchers and pedals, some of them very expensive and well established. All were tested and compared with our switching system during development and the fact is unchanged; no true or buffered bypass is completely silent. It is not even physically possible to make a fast and silent bypass switching system, not even in audio theory (this topic is for some other article). According to our knowledge and tests, we have developed one of the quietest switching systems in the industry.



Three bypass options

Although we have written in the initial description that the Module 4 has two bypass options, true and buffered, it actually has 3 bypass options: True bypass, buffered bypass and buffered bypass with ORANGE coloration.


Most people probably know the difference between the true and buffered bypass. A lot has been written about it on the Web and each type of bypass has its pros and cons.


The Module 4 has a fast relay true bypass option built in because it has to be the first in the chain. In that case, the user can use other pedals which should be first in the chain as well. For example, when the Module 4 is first in the chain and in true bypass, it will not interfere with a following fuzz pedal. This is the main reason why we built true bypass into Module 4, otherwise we probably wouldn’t have implemented it.


Another option of the Module 4’s bypass is the classic buffered bypass. When this option is enabled, Module 4 works as a high-impedance-high-headroom low noise buffer. That’s how the signal integrity is preserved. It’s a great option for people who don’t use fuzz or similar pedals that work on the principle of input impedance interaction with pickups. It’s also a quieter bypass option than true bypass. That kind of buffered bypass makes the Module 4 an ideal candidate for a pedalboard buffer.


The ‘ORANGE coloration’ in buffered bypass – Why this is a great feature for a pedalboard chain?

A third and very interesting option is the same buffered bypass, but with the ORANGE button on. When the ORANGE button is on and the pedal is in buffered bypass, the impedance of the buffer is no longer constant (about 900kΩ). In this case, the buffer input impedance is controlled by the compressor which is still running in the background. To our knowledge, this switchable bypass feature has never been implemented on any guitar pedal. It is similar sounding to the original OS bypass but the Module 4’s signal is buffered afterwards. The original OS bypass uses a SPDT switch and the passive guitar signal is always loaded with the circuit and the following signal chain. This way, the player gets a very similar bypass EQ response and feel as when the Module 4 is active (but without compression of course). It’s a pretty cool feature, give it a go!


The practical benefit of this ‘ORANGE’ bypass is that the rest of the pedalboard chain does not get a different EQ signal when the Module 4 is switched from ORANGE mode to OFF. You can set the desired compressor sound and switch it to ‘ORANGE’ bypass and the EQ will remain quite similar. In other words, there is no need to re-adjust the tone controls on the possible next drive pedal, when the Module 4 is bypassed this way. Our working term for it is ‘Always Orange’.


New enclosure and custom silent footswitch for the Module 4

With a new custom aluminum enclosure, we wanted to give some of our future pedals a new recognizable look. We also avoided some mechanical design limitations which the classic Hammond enclosure sometimes has. This does not mean that we have completely given up on Hammond or that we won’t do something different in the future. We’re really happy with the result and hope the Module 4 will fit well on your pedalboard 🙂


Also, a custom silent footswitch with no breakable mechanical parts was developed for this enclosure. The planar inductive PCB sensor knows when and how much the footswitch is pressed down. This new system opens up various possibilities for our future designs. As for future designs, we will continue to use new technologies.




The last few words

“We’re sure you’ll agree with us that it’s not enough just to make a perfectly working device, it must be nice looking and the learning time to get comfortable with the product needs to be as short as possible” – we said this when we released our versatile Unit67 pedal in 2018 and we say it again today.


The compressor is a specific but powerful ‘dynamic changer’ tool for sure. Widely used. It’s always good to remind ourselves how some controls work, like Attack or Release, why the Blend is some type of Ratio control or what the Expander feature is used for etc. But these things are actually quite simple 🙂. Just experiment with the settings, listen and adjust the controls until you’re satisfied with your pick-response dynamic and your guitar sound.


Of course, we are quite confident that this pedal will satisfy beginners and more advanced users alike. We simply made a pedal to be practical for our own needs in various situations, because we are all musicians too. So, whether you play at home or live on stage, the Module 4 is a great tool for most of your compression needs.


Every company has its own vision, goals and product ideas. We are always doing our absolute best to design good sounding, road tested and user friendly pedals, with really useful features. Are we successful in achieving that? You will have to decide. Hearing from satisfied customers always makes us happy. The best thing about our job is having an opportunity to satisfy customers with the musical and practical values of our creations. On top of that, DryBell’s business policy is strongly focused on customer care, before and after purchase. All customers’ orders are processed promptly and mostly shipped the same working day. All inquiries and all kinds of requests are responded to as a top priority in our company. So, whether you would like to know more about DryBell pedals, have any concerns using them or you need some advice, you’ll get our feedback (from Martina, Kruno, Marko or Zvonch) the majority of times in less than 24 hours, no matter where you are in the world!


The lovely people involved in all of our projects have been an extremely important part since the beginning of DryBell. Another important part is to have fun doing it. The third and probably most important thing is that we must strive not to work too much overtime and manage a balance between work and family time. Sometimes you have to be a magician to make it all work, but it’s always worth it :). We are very proud of our entire Team, who are always making things the best they can and the best way they know, evolving with every new product. Finally, we would like to say a big thank you and to congratulate our entire DryBell team.


With all that being said, it has been a challenging but fun almost two year journey for us and now it’s up to you to try the Module 4 for yourself. We hope you’ll like it!


Thank you for reading this article.


DryBell Team
Zvonch, Martina, Kiki, Marko, Luka, Kruno, Tom & Marijan
Supporting friends:
Zlatko, Mario, Gordan, Borna, Miro, Silvio, Boris & Jasmin



Module 4™ is a trademark of DryBell Musical Electronic Laboratory.

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Custom photocells for the Vibe Machine

February, 4th, 2013


January 2013 is already behind us!

2012 was a very big year for us here at DryBell with the launch of the Vibe Machine. Many of you will know that 2012 was the year we properly arrived on the boutique pedal market. We are really proud of everything that was achieved and want you to know this is just the beginning!
We work really hard every day to assure the best product for our customers with fantastic customer support. There are tens of thousands of emails in our inbox and we honestly really enjoy communicating with you.


A strong focus on the Vibe Machine

Four years ago when Zvonch and Kruno first started redesigning a vibe pedal they didn’t know what awaited them along the way. A very high goal was set to build one of the best vibe pedals in the world. Back then they didn’t know how big a challenge that was, and that around four years of development would be needed to make it all happen. That task led Zvonch to dedicate DryBell to specialize only in Univibe type pedals. So for now at DryBell we are solely focused on our vibe pedal series. Now, with this mountain of work behind us, we really feel ready to move forward.


The Team

Apart from playing the guitar, Zvonch is an innovative engineer with huge experience in professional industrial electronics and guitar audio devices (pedals, amplifiers, etc.). Kruno is a great guitar player who has been exploring guitar sounds and tones his whole musical life. Our products are made by musicians for musicians! So we are really confident here at DryBell that we have a great team which has what it takes to leave an indelible mark on the guitar pedal world. Ready? Here we come!


A/B testing of two vibe pedals

If you are familiar with vibe pedals then you will know that there are only a few companies with top notch vibe pedals on the market. This is no coincidence. Why? The answer lies in the photocells – they hold the key to the Vibe’s magical characteristics. You cannot find two photocells with exactly the same characteristics in the whole world. It is extremely hard to develop proper photocells for a quality vibe pedal; this is why only some companies have succeeded in doing so. If you have had a chance to test more than one brand of vibe pedal or have read people’s comments about vibe pedals on forums, you may have come to the conclusion that each vibe pedal is different. You can even take two of the same vibe pedals from the same manufacturer and A/B test them and you’ll find they sound a little different from each other. Of course they do! We are talking about real vibe pedals here that use photocells. This is perhaps the reason why all guitar players who truly fall in love with the Univibe sound will search high and low to find the right vibe pedal for them. When they find it, they rarely let it go!


The photocell behaves like human eye

The photocell’s characteristics are similar to the human eye. If you wake up in the middle of the night and switch on a strong light your eyes will need some time to adjust. Similarly if you went from strong sunlight into a very dark room your eyes would need time to adjust. The same thing happens with photocells – the resistance value of one particular light intensity is not always the same. It depends on whether that photocell has been in the dark or in the light before testing its value. This is called light history or the memory effect of the photocells. All vibe pedals with photocells behave this way and that’s why they can sound a little bit different from day to day. Some companies have been successful in minimizing this effect, but bear in mind that this is also part of the mojo of vibe pedals that use photocells. Electronics and construction development were not such an issue for us; the biggest problem was how to get good photocells in order to have the best quality vibe pedal.


The new test equipment in production

Two massive developments made last year really important for the Vibe Machine. Firstly we developed special testing processes and devices for selecting the photocells, which brought us excellent results in the Vibe Machine’s sound and helped us shorten production time. Second was the great news that we were finally able to create our own custom photocells – these definitively lifted the Vibe Machine’s sound to a higher level! It now has a subtle chorus and a bit more of a pronounced swirl. We are very proud of this development! But remember the key here is not just the new customized photocells but also the ability to select each one in their detail and quality. Our production process consists of several complicated selecting procedures, and each procedure is performed with very innovative devices (three microprocessor based testers that are testing 18 parameters of each photocell). With these production processes we are able to select the photocells we want so they are just right for their purpose. All of last year was spent focusing on these developments, which is one of the reasons we chose not to start distributing with dealers or shops yet, despite many offers. Last year we forged a very successful relationship with one of the world’s biggest photocell companies, we worked with them for over six months just to perfect the custom photocell design for the Vibe Machine series and they have our sophisticated equipment for testing samples in their warehouse.


The next batch of Vibe Machines is almost ready !

So, the next batch of Vibe Machines will be the first to have the new custom photocells, especially designed for the Vibe Machine series and precision selected by us. The whole development project took several weeks longer than anticipated and that’s why the next batch of the Vibe Machines won’t be ready until late February!
But trust us it will be worth the wait!


Your DryBell team


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