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HEM Sp. z o.o.
Aleje Jerozolimskie 475
05-800 Pruszków | POLSKA


MYTEK DIGITAL is a firm that was set up in 1992, but I get the impression that we do not know most facts about it and we still underestimate its contribution to the success of the Polish HEM company. I hope that the interview below will change that, at least to some extent. The meeting took place on March 26th 2019 in Krakow.

YTEK DIGITAL is the brainchild of MICHAŁ JUREWICZ, a Polish engineer who used to work as a technician in New York recording studios. His devices are known both in the pro world and in the domain of home hi-fi, and are highly rated for their excellent sound, high-class engineering and moderate pricing. However, not too many people know that Michał Jurewicz is only one element of the puzzle – the other one is the Polish HEM company and its founder – MARCIN HAMERLA, while almost all Mytek company products are now manufactured in Pruszków near Warsaw.

HEM is now quite a large engineering company employing 20 people, including 7 engineers. The firm is entering a new developmental phase with the Brooklyn Bridge model, so I asked Marcin for an interview and he came to me with PAWEŁ GORGOŃ – the engineer who first co-designed the Brooklyn DAC+ and then the Brooklyn Bridge model. We had enough time to talk and to listen to music in my system with my SACD player, and then with a Mytek file player. You can read the interview below.

Marcin Hamerla (on the left) and Paweł Gorgoń (on the right)

Marcin Hamerla and Paweł Gorgoń are being interviewed by Wojciech Pacuła.

WOJCIECH PACUŁA: Let us start with a fact that most people are probably not aware of, i.e. that HEM is a firm that has contributed to the success of the Mytek company – is that correct?
MARCIN HAMERLA: I think that HEM is quite well-known in Poland, but not so much outside Poland, even though all Mytek products have the “Made in Poland” label. However, if someone disassembles one of the devices, they always see my name on a plate :)

It was like this: Michał set up the Mytek company in 1992 in New York. Back then, he was working as a technician at a recording studio and designed a device to be used there, to aid group recordings – one called Private Q or simply PQ, a headphone distribution system that we are still manufacturing today, although we thoroughly redesigned it a few years ago. He later designed a few analog-to-digital converters that were quite simple and not too many of them were sold. In 1998, Michał was working on the D-Master project that did not take off in the end.


So, you both met then?
MH: Yes, we met to talk in the same year. After we drew up a contract, I started working on the devices that Michał had worked on earlier and I finally completed the work – it was a complementary pair of multichannel converters, 8x96AD and 8x96DA. Right afterwards, the production of these devices was moved to Poland and then I started preparing new devices for Mytek. So, since 2000, all its devices (except for the AMP amplifier) have been designed by me and, recently, by my people. The HEM company has also been manufacturing them since then.

So, which of the devices have been recently made?
MH: The Brooklyn DAC+ is a result of teamwork.

PAWEŁ GORGOŃ: Yes, the DAC+ has been created by the team, but we worked fifty-fifty on the Brooklyn DAC.

What does the process of model exchange look like in the Mytek company? Who comes up with the idea – you or Michał Jurewicz?
MH: We have recently been coming up with ideas, earlier it was Michał. At the moment we are such, let’s say, spiritus movens. It started when I was to write software for Michał and after all the years we are responsible for the whole R&D and production, we finance the whole thing, provide support and deal with distribution.

So, what is Michał’s role?
MH: Michał is the key person. We all see him, as he is responsible for PR and product promotion, but this is not everything. We are now coming up with product ideas, although the Manhattan and Amp were invented by Michał, but the way of manufacturing, the final arrangement, etc. – it all has got to be approved by him and he must like it. For example, Michał suggests which chips or DACs we should use. It is cooperative work each time.

PG: It is very important that Michał listens to and approves everything. Though we know how to do the job, we ultimately try to translate what Michał would like to achieve into a circuit.

Are changes made sometimes?
MH: Sometimes, after a device is sent to the US, Michał suggests some changes – like in the case of the Brooklyn. When it comes to the Bridge, however, he made no remarks.

PG: Michał added a phono stage to the Brooklyn, one that we – he and I – have made together, in the end. It was also very important that Michał introduced the MQA decoder into the system – it is a big thing. The first version of the Brooklyn DAC PCB was without the MQA and Michał brought this idea to us directly before the production stage, so we had to start everything from the beginning :) However, such things happen and, as a result, we got one of the first DACs in the world with the MQA decoder.


And it was not known at that time if the MQA makes any sense at all, was it?
MH: It is still not completely certain where it is all going, but judging by the number of products equipped with the MQA decoder, it has probably caught on – even the new DAC ESS has the decoder. Thanks to Michał, Mytek had it already at the very beginning.

When did projects start to originate in Poland?
MH: Starting in 2000, production was moved to Warsaw, in the sense that we started designing and manufacturing everything in Poland, and then we also began to deal with distribution. Since then, we have started to develop faster. Our next project was the eight-channel A/D converter that was quite popular all over the world. Still, these were all “pro” devices.

These devices were becoming more and more popular at recording studios, but some of them were also sold on the “hi-fi” market. In 2008 or 2009 – I do not remember exactly – we started designing a device that finally took on the form of the Stereo192-DSD DAC. We spent a lot of time discussing what it would look like and what it would have inside, and we finally decided to decode DSD signal, which hit the bull’s eye.

I remember that right then, at the end of the work, Michał made the dream of his life come true, i.e. he went on a sailing trip across the Atlantic and I would sit and work days and nights to finish the converter :) We started production in 2011 and the device was a huge success. We sold a lot of units and the company grew threefold thanks to that.

With such a successful product, it is probably hard to come up with the next step, isn’t it?
MH: Of course. At the beginning we did not really know what we might do next. We started by changing the inner company structure. We had few engineers and quite a lot of technicians back then.

PG: I came to work for Mytek at the end of 2012 and that was the moment when the number of HEM employees changed rapidly, and the structure of the company also changed, i.e. the R&D department grew.

MH: We wanted to sustain our company development, so we needed new ideas and people who would be able to bring them to life. The three of us used to design together – I was responsible for the hardware, i.e. electronics, Adrian Żugaj – the head of production – made mechanical drawings and Michał Rzepczyński was our programmer. We talked a lot to Michał Jurewicz then and we even quarreled a lot, as Michał wanted the device to be 1/3 rack wide and I wanted to make it ½ rack wide, as I assumed that it was impossible to put it all into such a small housing. In the end, we followed my idea :)

Then, it appeared that we needed to have more people in the Research and Development Department. The company started undergoing transformation – there were fewer and fewer technicians, and more and more engineers.

PG: If we look at this from a broader perspective, the number of people stayed the same, but the company changed its percentage composition, if I may put it that way.

In what ways is a technician’s job different from working in R&D?
MH: A technician oversees production and is responsible for running machines. The whole production process is quite complicated and we commission automated stages to external contractors, while the assembly of the final product takes place at our company and is performed by assemblers. At this stage, an almost ready device is created – it only has not got a cover and, naturally, it is not turned on.

Then, it is given to technicians who connect it to a power supply and check if everything starts correctly, upload software and then test the operation of all the functions. Sometimes they also eliminate assembly errors.

PG: In R&D, work mainly consists in developing the design of such a device – starting with the housing design, the selection of elements, design of the motherboard, up to writing software. It is software that takes the most work, as everything is now focused on software.

So, it is the year 2012, there are changes within the company – and what’s next?
MH: In 2012, I went to Warsaw University of Technology, my Alma Mater, in order to meet my former supervisor, talk to him and also hang some notices informing that we were looking for promising students.

Paweł Gorgoń with the Brooklyn Bridge in his hand

PG: There was such a notice and I still remember where it was hung, although I did not come to the company that way.

MH: We then employed one or two people and I thought we did not need anyone else. However, we received a call from Paweł, a student of Warsaw University of Technology at that time, additionally recommended by his professors. I told him we did not need anyone anymore, but he kept on coming and reminding of himself for so long that…

PG: …that they finally employed me :) My adventure with audio started quite early, i.e. on the second year of my studies. That was a coincidence, as I enrolled in a typical course in electronics, not really connected with audio. However, the lecturer was very nice and I talked to him once.

I asked him whether there were any companies in Poland – companies, not small manufactures – that dealt with audio equipment production. I had always been interested in that – I am also an amateur musician. I was lucky, as the lecturer knew Marcin was looking for someone. In this way, I found a useful contact. Unfortunately, Marcin had already hired someone – a person with more experience…

Which faculty were you studying at?
PG: It was the Faculty of Electronics and Information Technology. I did my MA studies and got my engineer’s diploma at the Electroacoustics Division. However, on my second year of studies I still did not know what I wanted to do in the future. Marcin did not really want to hire me. Some time passed and I tried to contact him at the beginning of the third year, and it came to nothing again. After the next six months, at the beginning of December 2012, I got the job of my dreams – with HEM. And it was right before the Christmas celebrations :)

Marcin, tell me how Paweł convinced you to hire him.
MH: He used his personal charm – I am not kidding :)

Paweł, did you have an idea of what you wanted to do in such a company?
PG: I liked its profile. I liked sound as such, electronics and programming – and here I had it all together. HEM is not only an audio company, but also an engineering company. It is exactly what I had been looking for.


In 2012 you had already experienced the success of the Stereo192-DSD DAC, but you still did not have the Brooklyn?
MH: No, we had not talked about it yet, but were only thinking about what was next. We started carrying out our test project and came to the conclusion that we needed to make a good analog-to-digital converter, something like the Stereo ADC, an earlier product of this type offered by Mytek. The project was mainly, but not only, carried out by Paweł Gorgoń and Przemysław Górny, currently the head of our R&D Department.

PG: It is now worth telling you something more about Przemek. He has made a big contribution to the company development, organization and planning. These are the areas that we had to master while the company was growing and his input has been invaluable. This was, of course, happening in the meantime, when we were already working on the ADC.

MH: At some point, somewhere after we have carried out half of the work, I joined the team to supervise the transformation of some of the elements – this was the last project that I influenced to such large extent. In this way, we created the Brooklyn ADC, i.e. an analog-to-digital converter designed for recording studios. We have mainly been selling it in the USA. It is an excellent converter and our mutual friend, Dirk Sommer from and Sommelier du Son, has also been using it.

However, while designing the device, we always had the thought in mind that it would be transformed into a digital-to-analog converter, the Brooklyn DAC. Changes consisted in replacing the ADC circuit with the DAC ESS Sabre 9018K2M and designing the analog section, to some extent based on the one from the Stereo192-DSD DAC. We also had to develop stronger power supply, appropriate for a headphone amplifier that simply was not part of the ADC.

The Manhattan model

PG: It is worth mentioning that the design of the A/D converter was very important to us, as we implemented a lot of our technologies and ideas in it. We developed the digital section from scratch, including USB transmission, the use of color displays, safe software update and communication with the control application that we also had to develop. This required a lot of work. The most important thing is that this section is entirely “ours”, i.e. we designed and programmed all the elements.

MH: If someone would like to see what sound engineering is all about, it is enough for them to disassemble our device and a device made by any good manufacturer from Japan. Even a little technical knowledge will allow them to appreciate what they will find in Mytek devices. What I have in mind is, for example, systems integration – we have one board with all sub-systems integrated already at the design stage, which simply results in better technical parameters and sound. In other devices we often have a tangle of wires and a lot of PCBs that are attached to one another like LEGO blocks.

PG: What is important to us is engineering effectiveness – what we make must be elegant and sound well. One can buy ready-made solutions from subcontractors, but the problem lies in their proper integration. Such a project cannot be transformed later on. We were only able to do it from start to finish starting from the “Brooklyn” project.


However, in your latest product, the Brooklyn Bridge model, you have used a module “from the outside” – the file player module.
PG: Yes, of course – but this is how it goes, this is how we learn. We wanted to add something extra to the converter, something that we had not dealt with before. It is easier like this. But this is just the beginning…

However, first there was the Brooklyn DAC+.
MH: The Brooklyn DAC was a huge success and the sales were really high. After two years we came up with an idea that we can largely transform the device at a low cost. The thing is that a few talents started developing within the company and having impact on it: Jarek Jabłoński, Rafał Bednarski and Arek Sęk. What is more, Michał Jurewicz suggested using the new ESS Sabre ES 9028 chip.

The Brooklyn DAC+ was created right after we moved to our new seat, at the end of 2017. The digital section remained almost the same as in the basic Brooklyn DAC model. We changed the chip used in the DAC and the analog volume control circuit which is much better now, and improved different smaller elements. We also thoroughly upgraded the analog section. The components are the same, but we changed the topology of the circuit. The analog section was created thanks to the ideas invented by the people that I have mentioned. As I am saying – we significantly improved the operation of the analog section using simple methods. At the moment, it appears to be better both in terms of measurements and listening tests.

PG: We also improved the power supply of the analog section and the converter. However, the main changes consisted in redesigning the topology. A few small adjustments were also made in the software that is being developed all the time. A useful function is the Triger signal input and output, which makes it possible to control turning on the whole system.

MH: The device sold very well for the next year and a half. In mid-2018 we came to the conclusion that it might be worth creating a streamer based on the Brooklyn DAC+. It was during the exhibition in Munich.

PG: We decided to use the module that we have in the expansion board for the Manhattan DAC II, but we will build it in as an integral element of the device. Streamer is quite a complex thing – in fact, it is a microcomputer. At the moment, we are using a module “from the outside”, but we are already working on our own solution.

In what ways is such a solution going to be better than the module you are currently using?
MH: It will be better in terms of engineering – and this is always our starting point. The most important element will be better integration of the components, thanks to which all the elements will better co-operate with one another. Such a circuit uses less power, because of which we get less audible interference. It is always about interference.

Paweł is making the final setting adjustments in the Brooklyn Bridge

So, your next project is the integration of a file player with the Brooklyn?
MH: Yes, exactly – it is our plan for the time being.

Is it still going to be the Brooklyn, or some new product?
PG: We are not able to answer this question. We will see, as now we are at the planning stage. We need a lot more time to turn this into a product.

PG: We will surely be able to deal with more formats – I do not know which ones exactly, but it will definitely be better than now. We have had experience with USB that we design ourselves and we would like to have the same thing in our player. However, let us remember that the streamer module can be used for PCM 24/192 and DSD signal, which is enough in 99% of cases. It is even more adequate, as streaming services do not offer music characterized by better parameters. If they do, it is just the absolute margin.

Anyway, it is also important what is done to signal and signal itself is not the only thing that matters, right?
PG: Exactly. Digital filters are an important element, for example. In the Bridge we have a selection of seven different filters for PCM, but they only work when we turn off the MQA module. If it is turned on, it also constitutes a digital filter for PCM signal. If we want to use the remaining seven filters, including the apodization filter, MQA has to be turned off in the Bridge’s menu.

When the MQA decoder is turned on, some operations are performed inside it and some are carried out in the converter. The latter, however, are specifically adapted to what is done in the decoder. That is why there is no filter selection. That means that the decoder also does something for signals that are not MQA coded. In my opinion, the effect is positive. This cannot be omitted, as it results from the principle of operation. It can only be completely turned off and then signal is transferred directly to the converter where one can select filters.

MH: The idea of MQA filters was that each A/D and D/A chip spoils something and one must correct it using filtration at the digital stage. Coefficients are selected for the chips and the decoder in such a way that they compensate each other.

So, is the main role of the Bridge to convert digital signal to analog signal?
PG: I am not sure if we can put it this way. It seems to me that network functions are most important in it. It can perform almost all the functions of the Brooklyn DAC+, but without the AES/EBU input and clock inputs. We gave up these in order to include a LAN and USB input for a USB flash drive, at the same adjusting to standards used in home appliances.

MH: In my opinion, the advantages of what we did in the Bridge result from the fact that we are experts in the domain of constructing digital-to-analog converters. There are many companies all over the world that make good file players but have no idea of digital signal conversion. We do :) We think of the Bridge as of a streamer which has a real DAC inside.

Marcin Hamerla and Paweł Gorgoń listening to the Brooklyn Bridge in the “High Fidelity” reference system

PG: We used a module manufactured by the Conversdigital company in it. It makes it possible to play files both from LAN and a USB flash drive. The circuit also allows you to play music from streaming services, such as Tidal and Spotify, and it is also compatible with Roon. It is controlled using a dedicated application called MConnect control for Android and iOS. It is worth mentioning that there are two versions of this application – for phones and tablets (an HD version). Signal from the streamer module gets to an XMOS chip with an MQA decoder. It is a programmable circuit which is most often used for USB inputs – we have our own circuit for USB and upload the software of an MQA decoder into XMOS. The logical heart of the whole device is an FPGA chip which controls the transmission of digital signals – and we write software for it.

Can we choose between analog and digital volume control?
PG: There is a selection of analog and digital volume control, and it is true for all the outputs. In fact, separate control for headphones and line outputs is carried out on the logical level, while physically it is done digitally in a converter (ESS) or in a dedicated analog circuit. Only at the last stage a choice is made whether to supply signal to the front or to the back output. By the way, the digital controller in the converter is very good, as it is put in the part of the path where signal is converted anyway into a form suitable for conversion.

One of the names that you use in press materials is “Femtoclock” – what is that?
PG: Femtoclock is actually a very good quartz generator which is used to clock only the converter circuit – the ESS chip itself. We have been using it since the original version of the Manhattan. It has improved the location of sources a little, at least from what I remember, as the selection was made quite a long time ago. You know what it is like with sound. A lot of small changes result in an enormous difference in the final effect.

The analog section of the Bridge is balanced, right?
PG: Yes, it is a balanced system, but it works a little different than usual, i.e. signal is send symmetrically from the beginning to the end, but it is desymmetrized on the way, in order to make use of the advantages of such a circuit, regardless of the type of the receiver. This is why signal on RCA outputs is simply taken from one signal half and it does not need to be desymmetrized (a symmetrical circuit is similarly understood by the Accuphase company – Editor’s note). It makes it possible to use the whole circuit, both for XLR and RCA outputs.

I also have a question regarding the components. I can see through-hole Wima capacitors here, but the whole rest is surface mounted. Is there a huge difference in quality between different resistors, let’s say? MH: Of course! However, we get the impression that Vishay is the only resistor manufacturing company nowadays … We used to buy resistors from Beyschlag, Philips and Draloric. Anyway, we use the type of resistors called the MiniMELF (Metal Electrode Leadless Face), as we think they are very good. They do well both in terms of measurements and listening tests. I selected them a long time ago when we started cooperating with Mytek.

PG: There are a few advantages of using surface mounted components – only this technology allows you to use better operational amplifiers. Through-hole circuits are slower, as there are also leads in the system, introducing delay and other types of distortion. Using more professional engineering terms, each hole introduces parasitic inductances, etc. When it comes to capacitors, through-hole elements are better, but only SMD is good for integrated circuits and resistors.

Companies often choose THT, as they do not have the technology to produce SMD in place and not because it is an objectively better method. But… There are people in our company who would be able to manually assemble a whole such converter, even though most of the elements are surface mounted here. Sometimes we assembled prototype units for Michał in this way, or even of-the-shelf products, if we needed to supply a few quickly.

MH: Exactly – in this way we assembled the first Brooklyn unit, as we were in a great hurry. It took my boys two days.


Is HEM planning to do new things?
MH: At the moment, the HEM company manufactures all devices for Mytek, but not only. We also produce industrial electronics which we, perhaps surprisingly for some people, export in large quantities to China. In the future, we will also make other things for the industry.

When it comes to audio, we are mainly experimenting with the analog. The changes we made before in the Brooklyn yielded such good results that we want to take this forward and make something even better. As I am a “headphone” type of a person and I pay a lot of attention to headphones, we intend to improve the headphone amplifier. I think it is very good at the moment, but we would like to make something even better. However, it is still going to be done within the scope of a new DAC with a file player. The form will probably remain the same.

Thank you!

MH: We also thank you!
PG: See you! ■

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