Lars Moltke, CTO at Bow Technologies from 1995 – to date
Lars Moltke worked as CTO for Bow Technologies back in 95-96, where he did the electronic design of the ZZ-1 and the ZZ-8.
The period 1996 to 2007 was a bit up and down time for Bow Technologies. Several designs were done by different people, and the Lars Moltke “signature” was, well let’s call it … “missing”.
In the meantime Lars Moltke had several jobs, as CTO at an electronic Sub Manufacturer with the responsibility for soldering machines, SMD Pick and Place machines, purchasing and stock pipelining of components and quality control according to military and aerospace workmanship.
Another challenge for Lars Moltke was starting up two new companies and the establishment of production plants from scratch to full automatic production lines. Also a job where structure, mindfulness and overview through the process were the key point. Long away from the audio business, but in a related environment where the ‘bull terrier way to the goal’ is a needed skill to be successful, Lars kept himself busy at home with all kind of different audio designs. A virus is hard to destroy, especially if it is an audio virus!!
Finally Lars ended up being a consultant who was specialized in manufacturing, controlling order flows, still having the audio design as a hobby and he was asked regularly to do some of the difficult Bow repairs.
In 2007 Lars Moltke was asked to return to the company to design a new line of electronics and to tweak and upgrade the Bow circuits.
Before the return of Lars Moltke, Bo Christensen was asked by an external design company, if they could support Bow Technologies with a new DAC design, called MRK II V0. Bow Technologies then made some upgrades from the old DAC PCB equipped with the Burr Brown 20bit PCM1702 to the new PCB equipped with the 24bit PCM1704.
Lars Moltke, being back at Bow Technologies, started to do some tweaks and modifications which resulted in the MRK II V0-V9. The last upgrade version sold from Bow in 2008 was V9. Then in 2009 the Bow Technologies company was sold and became part of the group to which already brands like PrimaLuna, Mystère, Thule, Kiseki were belonging. A new direction, a new future?
From the year 2008 to 2009 Lars Moltke was asked to join a new project of Bo Christensen, the brand Artora, for which he did the mechanical and electronic design of the ArtoPLayer 1000 and the ArtoAmp 150. Also there the key point was to create great looking and sounding design.
While Bow Technologies was sold in 2009 to the “Durob Group” to join brands like PrimaLuna, Mystère, Thule Audio and Kiseki, more or less immediately after, the worldwide economical crisis started which we still are suffering and probably have not seen the end of yet. It’s not said, that this sale has caused this worldwide crisis, but it is true that because of the crisis the plans for the revival of Bow Technologies were kind of delayed as other projects needed all our attention during these roaring times.
During this period several owners of Bow Technologies equipment came up with several questions, service issues and more. Assistance could be given by Durob Audio with help of Bo Christensen and certainly Lars Moltke, the former technical partner of Bow Technologies. Soon after, the plan was made by Lars Moltke and Herman van den Dungen to develop new versions of the ZZ-1 and ZZ-8. These new models, ZZ-2 and ZZ-9, are under development now and we agreed to take all the necessary time needed, to come up with “amazingly” improved machines. No stress allowed. Not during the design, not during the final use at the customer.
So, in 2009 Lars Moltke started trying all kind of different things to find a best way to improve his latest ZZ-8. One of the many things he did was transferring all the modifications from the DAC MRK II V9 design to the “old” 20bit HDCD design (MRK I). And he was amazed. And confused as well ….
The now updated old design was suddenly better sounding than the new!
To be able to evaluate components for the ZZ-9 platform Lars and Herman agreed that it was in strong demand to create an environment of making future upgrades possible and of being able to compare different components in an easy way. Therefore a motherboard was designed with the ability to use plugin pcb’s like we all know from our computer. This opens up for the possibility to exchange and compare components and boards during the never ending development of a product.
All tweaks and knowledge from the old ZZ-8 were recreated as upgraded modules. Feedback received from several customers all over the world, who have been evaluating the different upgrades was collected and studied, and they were all giving enough positive feedback in return, to tell us we were going in the right direction. These upgrades of the “old” ZZ-8’s are still available to customers all over the world, because we also feel that leaving the owners of the ZZ-8 “in the dark” is a bad thing to do. They have been a major part in the evaluation, and they made it possible to come up with a new ZZ-9 …
The main circuit was split into partial circuits:
The motherboard Power Supply
The first step was to find the correct basic power supplies for the motherboard which supplies all the modules. First of all the PSU’s were split up, so every module and circuit has its own regulator for making the perfect voltages available to the circuit not disturbing each other.
Different designs were built and compared – e.g. battery supplies, complex shunt regulators, linear voltage regulators etc. The best found was a zener diode, which works as a shunt, and then a serial transistor, which makes it possible to draw more current through the PSU. This is a combination of a shunt regulator and a serial regulator, but most important is the non feedback of the voltage regulation. Of course all has been designed with the best components and use of very low impedance capacitors with a lifetime of up to 25,000 hours at 125°C.
The standard RCA connector was a demand, but many new sources are now using the reborn Toslink optical standard, now with better quality plastic fiber. E.g. the MAC computers and all the new TV sets use this optical cable connection. The SPDIF is not thought of as being our ‘master input’, but it is a nice thing to have. Why not being able to attach the TV to one of the best sounding D/A converters in the world?
Another demand was to find the best input components for the SPDIF. There are lots of circuits on the market running at ‘higher speed than light’, but the choice of the rather old DIR9000 was made because of the good sound and the low jitter. Special capacitors in the PLL circuits are carefully chosen and make the right sonic performance. A high speed MUX was found to enable the possibility to select either the RCA or the Toslink input.
USB to I2S module
The use of a computer as the digital source has been in very high focus under the development of the new ZZ-9. A lot of evaluation has been made, and there is no doubt that a traditional hard drive or an SSD is a very good media and under ideal designed conditions is a better and more stable media than the CD record ….
Another fact is that by using the CD environment, the system is ALWAYS limited to 16bit/44.1KHz because it has to be compatible with old CD players. There is of course the now discontinued HDCD standard, which enables the media to run up to 20bit/44.1K, but there is no way to be able to play any kind of high res music.
Using the USB module together with the windows/MAC driver it’s able to play REAL 24bit/192K through the system and D/A converters. Upsampling of the music is also possible by use of DSP’s inside with e.g. the FOOBAR2000 or JRiver Media Player, and here the difference is truly ‘visible’. No doubt those computer players are a part of the future. A good reason for us to choose our USB module very carefully.
CD Drive unit
The newest version of Philips PRO2M drive is still compatible with the CDM12 Philips drive, but comes now with e.g. better servo, oscillator etc. A new mechanical adaption to the chassis is made, where damping of the mechanical resonance has been further taken care of.
The Oversampling filter / NOS circuit module
In the new design several ‘new’ techniques (some will call them very old) were used. One of them was to implement a Non OverSampling shift register, and this makes the impression of the sonic performance much more analogue and real. Several digital filters and sample rate converters were compared and the NOS were for sure the winner. This circuit is of course also made as a replaceable module, and therefore it’s possible to change it in the future if new developments justify that.
A Non OverSampling (NOS) register takes care of the timing of the I2S audio stream to the A/D converters. The use of no oversampling and no digital filter give the sonic performance a much more analog signature. The sound of the CD player has a much more analog character, making you think of listening to that good old turntable.
The D/A converters
A lot of D/A converters have been evaluated, but the choice of converters went back again to the ‘old’ Burr Brown Multibit converters. They are able to get the smoke, flesh and blood from the recordings out of the speakers into your livingroom. By aid of the now exchangeable modules it showed up that the difference between the very old 20 bit PCM1702 and all newer 24 bit D/A converters was very big. The 20 bit PCM1702 is much more correct, and it seemed to be kind of wall carpet on front of the speakers when listen to all other tested converters.
Of course new converter modules will be tested in the future, but for now Bow Technologies will place the 20 bit PCM1702 as the reference, well knowing the last 4 bits of LSB data in the audio stream will be truncated. A reference design of the 24 bit PCM1704 is off cause also made for customers, which wants the last 4 bits in the audio stream.
A hardware jumper has also been embedded to make it possible to either make the D/A converters run as balanced output or to configure them into stacked single ended output for non balanced use.
The analogue output interface
Several circuits has been built and tried. The best solution found was -can you believe it?- with an opamp from National. Also here the circuits are doubled to take care of a real balanced output. Stacked and non stacked configurations have been tested, but the NON stacked was found being the best solution.