Zero Feedback Technology

The most important technical aspect of our productrange is the zero-feedback technology. In the seventies Finnish Professor Matti Ottala discovered the importance of low-feedback. Until then all amplifiers were designed using high feedback. Matti Ottala’s breakthrough started a lot of low feedback designs. The benefits of the low-feedback designs compared to the standard high feedback designs were much faster amplifiers, better soundstage, detaillevel, transparency and so on. This leed to recognition of transistorised high-end amplifiers, and the beginning of the demise of tube amplifiers among high-end amplifiers.

The reason that feedback is used (though in smaller quantities than in the past) is that it is used to compare the input with the output, and adjusting the input so the output is exactely the same as the input. This way -at least in theory- the amplifier itself have no influence on the signal as these influences will be adjusted away.

All Densen models are zero-feedback designs. This means there is no feedback loop in the amplifier. The problems connected with feedback technology are the following (whether it is low or high feedback): The signal always takes some time to pass through the amplifier stages, therefore the comparison of input andoutput is not the comparison of exactely the same signal. This means that the theory that feed-back should improve sound by avoiding influence on the signal from the amplifier stages is simply theory and not true.

The fact is that feedback -no matter what degree- alters the signal and the result is: -dynamics will be compressed, -micro details compensated away, -details smeared, -soundstage altered, -speed slowed down, -transparency smeared and so on.

Naturally you will not have these problems with a zero-feedback design.

However the basic design must be extremely much better than feedback designs, otherwise the amplifier will not be stable. We are one of the few companies in the world (the only one ?) capable of doing this and the result of this is simply stunning, the combination of a MUCH better basic design and the zero-feedback technology results in: Extreme dynamics, detaillevel, amount of microdetails, perfect soundstage, transfer speed, transparency, and wide open sound. Combining this technology with the extreme care we take in the listening tests, during the development of our products, we can proudly say our amplifiers combine perfectly, high technology with extreme musicallity. In the future ALL products from Densen will be zero-feedback designs. The BEAT B-100 and all the other BEAT products will also be zero-feedback designs!

Relay controlled class A preamplifier stages

A volume attenuator can be constructed in many ways, but (as long as we stay in the analog domain) they all function in basically the same way: a signal enters the black box and a smaller signal leaves the black box. This is done in short by passing the signal through a resistor of size X. The easiest metheod of adjusting the size of the signal is by using a potentiometer (this is neclecting the use of volume IC’s which are becoming more and more widespread and are a even worse solution), which varies the size of the resistor when you turn the knob – simple and elegant, right? Well…. not quite. Usually the material in the potentiometer isn’t very “audio-friendly” and have a tendency to affect the audio signal, but there is a better way….

Instead of using potentiometer whose resistor material is of questionable composition, we use what is known as a relay controlled volume attenuator. The idea is the same – different size of resistor produce different sizes of signal, but the way this objective is obtained is rather different. When you change the volume on a Densen, you hear a little ‘click’, and if you adjust it more than 1 step you hear several ‘clicks’. These sounds comes from an array of high quality relays which feed the signal through different paths in a resistor network of high quality vishay film resistor known for the superior audio performance. By passing the signal through a few high quality components whose objective is to introduce as little change to the signal as possible (beside reducing it’s size), the same objective of controlling volume is achieved, but with all details, depth and nuances in the music saved.

Since the B-250, all Densen pre-amps and pre-amp sections have been based around a relay volume attenuator and paired with a amplification stage which is based around a 6 watt class A amplification stage (yes, there are also amplification in a pre-amp, just only a little).

Modularity and Upgradebility

When the DM-20 was introduced back in the 90’s, it came without a phono input, but there was a little slot for installing one, which could be bought seperately. Quite clever for time actually – if you didn’t need a phono input, you didn’t pay for one, and if you needed one, it could just be added. Furthermore, if you wanted to upgrade it later, you could just swap it.

But many were sceptic for mainly two reasons A) Is Densen going to be around in 20 years? and B) Why would they still make modules that fit my by then ancient amplifier?

A answers itself. B takes a bit more explaining, but for us at Densen it’s rather intuitive.

We do not want our customers to feel like they buy a product. It’s about an experience. That experience starts with a product which is of high quality and made with highest quality components – And of course it also looks good.

The experience is also good customer service, and what better way to do customer service than doing everything we can to make sure you won’t need it? That is why we offer a lifetime warranty. We can only offer a lifetime warranty if we are confident our products never fail, and you will never need it, thus creating the best possible customer service experience.

Then a few years later, you want to expand your system – no problem. All Densens all follow the same design philisophy and carry the same finish, so you can allways upgrade your system with a matching partner.

Now back to the DP-module you wanted to upgrade – owners of the DM-20 can simply upgrade to the current DP-05 variant. But many other companies ask us – why do you offer an upgrade, instead simply not making one and selling new units instead? Because we disagree with the practice. If you have an amplifier you love, you will be reluctant to replace it, and if you then call the manufacturer, and they tell you the only option is to buy a new one, you won’t come back to that company any time soon. And them most importantly – if we at Densen were customers at our company, would we like to be able to upgrade our amplifiers forever, or would we prefer to buy cehap upgrades as we go along? We don’t think this question needs answering.

So in conclusion, this small DP-module quickly became a part of Densen DNA: A promise of continued upgradability. In later models starting with the original B-250 from 2005 an ‘expansion port’ was added (as is seen on computers) where different modules can be fitted – surroundboards, DAC’s and soon a streaming board.

All this because a Densen isn’t just a product. It’s a promise of great music experience which allows you to forget all about the Hi-Fi and just focus on the music.