ANT4066 - audiophile replacement for the industry-standard CMOS switch 4066, found in many pre-amplifiers, cassette decks and other audio equipment, is now available.

Datasheet for ANT4066

In many good cassette decks, pre-amplifiers, receivers and other audio equipment industry-standard CMOS analogue switches were used. Most common is the "4066" chip in many versions by different manufacturers, also 4051/52/53 analogue multiplexors and some other CMOS chips were used.

Original 4000 series was cheap and cheerful at the time, however the switches had a fairly high resistance (70-150 Ohm) and what's worse - very non-linear resistance. As a result when these switches are present in the signal path of audio equipment, a sizeable amount of high order distortion is introduced and the sound quality suffers badly. In many cases old 4000 series chips can be replaced with much better 74HC series, also made by many major semiconductor manufacturers. Main limitation there is the supply voltage. 4000 series chips can withstand up to 18V (+/-9V on a dual rail supply) with some high voltage varieties up to 30V (+/-15V ) or more. 74HC series offers about a 1/3 to 1/4 of the resistance of 4000 series analogue switch, but only can work up to 11V (+/-5.5V) (NXP) to 14V (+/-7V) (Fairchild) supply voltage.

If the supply voltage allows than 74HC4066 will give a good improvement in the sound quality over a standard 4066. However it is still very much a non-linear resistor, thought the non-linearity is reduced by 3-4 times. ANT4066 provides much better linearity and can work with the supply voltages from 10V (+/-5V) up to 25V (+/-12.5V). It is the best replacement for 4066 chip from the sound quality point of view, however it costs considerably more than 74HC4066.

One thing is certain - 4066 does affect the sound in a very nasty way. If your cassette deck has this chip in the signal path than a replacement could be a very efficient and simple way to improve the sound. A simplest thing to do is to unsolder the chip and put a good quality IC socket in its place. After that it should be possible to swap the chip and the replacement (supply voltages and control signal levels permitting) and hear the difference. Watch out for the correct pin 1 position thought!

Nakamichi Dragon Cassette Deck modification with ANT4066

CMOS switches in the signal path of cassette decks - the list!