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ZAPfilter 2

High End Analog Stage for CD players.


Complete analog stage to replace existing circuits, to upgrade for true High End Sound Quality.
The ZAPfilter circuits are built without operational amplifiers in the signal path, to obtain a relaxed and warm tone balance, without losing precision and open soundstage.
The ZAPfilter is connected in between the D/A Converter chip and couples directly to the output plugs, of RCA or XLR type (True Balanced Operation).
From beginning to end the ZAPfilter circuits run in single end Class A mode, which again contributes to the highest possible sound quality. A distorsion mode of descending even harmonics, resemble the warm and pleasant sound of a triode amplifier, but with the open soundstage and precision of a high quality semiconductor amplifier. The transistors used are the best available audio types from ROHM (Japan), with ultra high linearity, high speed and low noise. 

The Circuit topology used does not use any type of feedback loop, even when running as a I/V Converter in the first stage, this is a worlds-only solution of this high quality.
The benefit of this approach is a very low amount of Transient Intermodulation Distorsion, (TIM) which keeps the sound clean and precise even at high sound levels, in complicated passes.

Normally the power supply decoupling capacitors have great influence on how an audio circuit sounds. Therefore we have completely removed capacitors from the power supply rails. To keep the power rails at low impedance, we have developed an ultrafast shunt regulator, that is capable of keeping the impedance as low as 9 milliOhms from DC to well over 10 MHz.

The construction of this feature required use of transistors, with a bandwidth of no less that 5 GHz!

The benefit is an even impedance at any frequency in the audible area. To compare the performance of the shunt regulator with normal capacitors is tricky, since it would require a theoretically indefinite capacitance. However we can compare within the socalled 'Audio Range' of 20 - 20.000 Hz. To make an equal performance with capacitors in this frequency range, would require 880.000 uF of ultra low impedance caps per supply rail. In other analog stages you would find something from 100 uF to maybe 1000 uF at the most. So the sound in the bass region is evidently firm and rock solid.
 

Shuntregulators have never been encountered in factory produced CD players in the price range of less than 8000.00 US Dollars!
But with the ZAPfilter You can get the ultimate solution for Your music, at a small fraction of that cost.
 

The size of the ZAPfilter, that can be fit in most CD players, is equal to two credit cards, plus the 230 V or 116 V Power Supply unit, that is a little smaller. 

True Balanced output now available on any CD or DVD player!

The I/V Converter which can also be setup as V input, can read positive as well as negative signal, so by simply configuring the input signal path, you can achieve true balanced output from any type of D/A converter chip, with no signal conversion or time delay in the negative or positive signal output.
This gives You a better balanced signal than most commercial CD players in the 2-3000 US Dollar range, where the normal approach is to convert a balanced signal to unbalanced forfiltering, and then using an extra phase splitter in the output. Too much fuss to let through the whole soul of the music!

Simply follow the setup instruction of the ZAPfilter to implement this feature, and connect ZAPfilter to a set of XLR plugs. In fact the biggest challenge is to drill the holes for the XLR plugs on the rear of Your CD player.
 

Input from DAC chips Unbalanced Output Balanced Output
Unbal. Voltage Yes Yes
Unbal. Current Yes Yes
Balanced Voltage Yes Yes
Balanced Current Yes Yes

As can be seen the ZAPfilter can interface directly from any D/A Converter type, to both types of Audio Signal Output without any conversions in the signal path.

The filter used is a second order Linkwitz-Reilly made with high grade (Unmagnetic) Poly Propylene capacitors from Vishay International. The cutoff frequency is set to 102 kHz for maximum overtone transparency and 100% compatibility with the host CD.


A Zapfilter mounted in the Sony XB930.


And here in an Onkyo.

These are two relatively low cost CD players, but with the ZAPfilter they were able to perform a beautiful soundstage with no listening fatique, and for the Sony - Compared to a factory standard CDP-XA-50-ES much better sound quality. When the XA 50 was upgraded with another ZAPfilter, it performed the best CD quality we had ever heard, anywhere! 

Better sound than a new CD player!

By implementing this ZAPfilter and maybe also an LClock XO You have the option to achieve a significantly better sound quality from your existing CD player, than would be possible by going out and spending up to 2-3000 US Dollars on a new factory CD player.
Starting out with a model such as the Sony XB 930, you end up with something that sounds on the level with a machine like the Copland 289, costing USD 3200.00.

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