The DeZorel trade mark is the sole property of DDM Elektro d.o.o. of Belgrade , SCG. Anyone wishing to confirm this can do so by contacting the Federal Institute For The Protection Of Intellectual Rights, Zmaj Jovina 23, 11000 Belgrade , SCG.

Any product so marked and offered in any manner which does not originate from DDM Elektro d.o.o. is therefore illegal and not true to the original. We cannot guarantee or support it. Parties to such offers and/or sales will be prosecuted to the full extent of the law.

If in doubt, please feel free to get in touch with us for confirmation.


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After a short period of reorganization, DeZorel is back!  

January 2011. DDM Elektro is making last preparations for a general company and portfolio overhaul.

A completely new site is being produced. This was necessitated by the changes in our portfolio, which are many and mandate a new site altogether. The site is expected to become active by mid-Febriary. All visitors of this site will be automatically re-routed to the new one.

On the power line filter front, we have a brand new filter available, called simply the "Super filter". It features still better noise and disturbance filtering, but also double the handling power and one half the output impedance of the standard filter. It is intended specifically for power amplifiers, as they are the single greatest power user anywhere.

It uses approximately twice the materials of the standard set of twin parallel filters, and resides on the same size of Mil Spec epoxy board as the standard filters. Thus, in effect, it replaces a standard filter in everything, size and price. It also makes possible a much improved choice of filters, enabling new models like Super Solo (1 Super filter inside), Trio (2 standard + 1 Super filter), Super Trio (3 Super filters), Quintet (4 standard + 1 Super filter) and Super Quartet (2 standard + 2 Super filters).

Beside the new filter models, DDM Elektro will also be offering truly ultimate quality models of headphone amp/preamps. Each will, among other things, feature a toggle switch (Apem, France) for source selection between A and B, so if you use only two sources, it will happily serve as a headphone amplifier AND a preamplifier. This has been made possible by the inclusion of an output pair of high quality, gold plated RCA Cinch connectors at the back, and the devices are capable of doing both jobs at once.

Fully discrete complementary designs, operating in true, pure enriched Class A mode, fed by Shunt power supplies. It is available in three technologies. Model HPHA-01 uses all bipolar technology, with Motorola/ON Semi 50W power devices at the output. Model HPHA-02 uses discrete FETs at the input and IRF MOSFETs at the output, and lastly, Model HPHA-03 uses vacuum tubes with vaccum tube power regulation. Models 01 and 02 are fully Direct Coupled (DC) amps, with a National Semiconductor op amp acting as the DC Servo. Response is 0 ... 400,000 Hz -3 dB (intentionally cut by a filter in the input stage, and if removed, the response extends to over 1,600,000 Hz).

Models 01 and 02 can actually power real world loudspeakers in a room and are limited only by heat sink size and power supply!

As ever with us, all parts come from world class companies, such as Motorola/ON Semi, IRF, Siemens, Toshiba, Wima, Fisher & Tausche, Panasonic, Alps, Beyschlag, etc.

News December 2007 - I

          As of December 2007, our DDM Elektro® and DeZorel® SE models of power filters will no longer use Neotech® Monocrystal wire for internal wiring, but rather van den Hul® wiring.

          Extensive tests, both objective in the lab, and subjective by audition have conclusively shown that this is a better solution, offering more spatial information and improving the sound stage. This is a virtually unanimous conclusion from all our reference test points.

          Even hard laboratory measurements, which are far from decisive in terms of sound quality, support this conclusion.

Neotech® and van den Hul® are registered trademarks of their respective owners. DeZorel® and DDM Elektro® are registered trademarks of DDM Elektro d.o.o.

News, January/February 2007


Our complete catalog has been added to our download section, and in two versions. DeZorelPDFstoryVer2.pdf is 1.54 MB large and is intended for those with broadband download capabilities, while DeZorelPDFstoryVer3.pdf is that same file in lower resolution, intended for those with dial-up connections.


DDM Elektro is now looking for serious distributors and dealers around the world, We have already branched out to our neighboring countries and are now looking to expand. Talk to us if you think we can do business!

New Case Looks

        In response to our customers’ demands, we now offer enhanced case looks. As before, the case comes in default black, however, customers can order the same large case models with a bead blasted natural grey aluminium fascia. This does carry a small price premium, however it is of no real consequence on the overall price.

Mk. IV Printed Circuit Boards

        In our continuing efforts to offer only the best, we have produced our latest version of the printed circuit boards, now in full Mark IV version. The latest version addresses issues from previous generation and very effectively deals with them.

        Boards are now specifically designed for lower and higher powered filters, no more sharing. They have been extensively tried and tested in several locations and in many configurations; all this is our normal procedure in the course of development. We can safely say these boards are our best yet.

        We saved the best for last – they carry no price premium, i.e. our prices have not changed as they were intriduced late in 2006.

The Scientific Community Takes Notice

        In the last several months of 2006, we have delivered several models to several fundamental research laboratories in Belgrade. A good example is the pharmacology reserach laboratory of Dr M. S. Prostran, MD, PhD, Department of Pharmacology, Clinical Pharmacology and Toxicology, School of Medicine, University of Belgrade.

        As of this writing, this lab is one of only six throughout Europe to be EU accredited as per the very latest standards. Their professional courses are accordingly recognized and honored throughout EU, despite the fact that Serbia is not a member of the EU. The accreditation was awarded after an international group of experts examined the entire course. Well done indeed!

        To achieve this significant recognition, these people need to be able to rely on their fine measuring and test equipment, and to do that, they use our power line filters. In fact, their satisfaction with our products is such that they note our company in their published papers, when summing up the equipment used to obtain the results described in their papers.

        We thank them for this courtesy, and congratulate them on their most worthwhile achievement. We are pleased to be a small part of their success story.

Upcoming products

        We are working hard on completely new products. Here you can see our prototype headphones amplifier, a pure class A unit capable of powering even the most demanding and awkward headphones – it uses hand matched 60W devices in its output stage in a pure class A Single Ended Push-Pull (SEPP) configuration. If there is a better one for ultimate fidelity, we don’t know of it.

        As you would expect from us, it is a true DC coupled design, with no capacitors anywhere in the direct signal path. A fast FET input, ultra low drift DC Servo circuit ensures complete stability under all operating conditions. Speed is awesome, however, when we speak of speed, we do not refer only to the input stage speed (easier on the manufacturer, looks good but is of limited practical value), we refer to the entire circuit, from input to output (harder on the manufacturer because it includes ALL subcircuits, but is of great practical relevance). In our case, speed is over 150 V/µS; the input stage alone slews at over 350 V/µS.

        Here you see the prototype board for full power amplifier voltage regulation. We have long maintained that if classic bipolar transistors are put under ideal circumstances, they will amaze with their potential fidelity. Comparing highly regulated vacuum tube circuits with classic, unstabilized bipolar circuits is like comparing a Ferrari with a FIAT, possible but outrageously ridiculous. However, when bipolar circuits are given the same basic chance the vacuum tube circuits have, things can change drastically.

As we are out to prove in real life, real products. At reasonable prices.


DeZorel as a trademark is now owned by DDM Elektro d.o.o. of Belgrade, Serbia. The old company split up, and the new owners have decided not only to uphold the tradition, but to invest substantially into new technologies.

This has yielded immediate and considerable benefits. For example, our product line has been cleaned up, and instead of offering a bewildering number of models and product lines, with sometimes unclear differences, it now offers just three models, making choosing among them a simple matter of your needs.

What used to be our top models, in terms of matching, has now been surpassed by even our entry-level model. New technologies and production methods have made this possible.

Our philosophy of after filtering isolation, yielding extremely low crosstalk between the outputs of any two filters of –120 dB or better has now been fully implemented even in our entry level model. Instead of offering just one filter, as was the case, it now offers two parallel filter sections, each feeding it own output.

And it does so at a lower price than before – without sacrificing anything in terms of quality! In fact, quite the opposite would be true, if anything, we have elevated our already high production standards. For example, instead of typical random sample quality check, we now fully test each and every module we make – no exceptions.

We used to offer symmetry matching of 0.1% only on our top models – it is now standard across the entire line. And it's still our GUARANTEED minimum specification, meaning it's the worst-case example; in practice this will be even better.

We still publish our comprehensive specifications, which we still guarantee. No myth and magic stories, hard specs instead.

We still make our cases from aluminium – nobody gives up a good thing unless they are forced to.

We still offer our no quibble 5-year international warranty; if there's no distributor or dealer in your area, we will undertake to honor the warranty. And we still support our exchange service policy – in the very unlikely event that something should go wrong, your unit will have its part exchanged, thus cutting waiting time to a minimum.

And your warranty is now transferable – in the unlikely event that you decide to sell your filter, all you have to do is give us the essentials related to the new owner in writing or by e-mail, and the warranty will be extended to the new owner.

But we kept some of the traditions of old, those that make us what we are. All our registered customers (in our present new guise) will be able to purchase our products at discounted rates. All will receive notices of new products as they appear, in form of an e-mail message inviting them to look over our site. All will be eligible for any special offers we make.

And we'll be here for one and all to consult before and after you make your purchase. We have always believed in after-sales service.

Last but not least, we have serious expansion plans. Power line filters were and will remain our backbone, but that's no reason why we shouldn't offer other audio related products. In the coming months, you will have the opportunity to read much more about them.


Copyright © DeZorel 2005