What is UPCI?

The AMM - UPCI (patent applied for) is a universal jitter attenuation device by Altmann Micro Machines (a manufacturer of audio equipment).

The AMM - UPCI is available for the following sampling frequencies:

  • 44,1 kHz f.e. CD
  • 48,0 kHz f.e. DAT, DVD
  • 96,0 kHz f.e. DVD
  • 192,0 kHz f.e. DVD, recording, research & development

The AMM - UPCI (go to the datasheet.pdf) has one digital input:

  • Toslink
  • or ST optical
  • or Cinch (BNC or XLR adapters are supplied if required)

and one digital output:

  • Cinch (BNC or XLR adapters are supplied if required).

The AMM - UPCI accepts S/PDIF and AES3 (AES/EBU) signals. The output voltage level is switchable between 0,5Vpp (S/PDIF) and 5Vpp (AES3).

picture shows AMM - UPCI - TOS - 96

The AMM - UPCI is connected between a digital audio transmitter, fe:

  • CD or DVD player / transport
  • DAT player
  • digital audio workstation
  • reference clock

and a digital audio receiver, fe:

  • DA converter
  • AD converter
  • Asynchronous sample rate converter
  • digital audio workstation.

The AMM - UPCI will strongly attenuate jitter and improve the audio reproduction / recording quality.

What is Direct-Clock-Injection?

There are several jitter attenuation or reclocking products on the market. All of these products suffer from the fact, that you need a cable, in order to connect to the digital receiver (f.e. DA converter). This will introduce new jitter, the cleaned signal will be contaminated again, before it reaches the receiving device.

Direct clock injection has been developed by Altmann Micro Machines, in order to overcome line induced jitter, due to transmission cables.

The AMM - UPCI uses direct clock injection, it is directly plugged into the receiving device with no cable in between. This ensures, that the regenerated and clean signal will reach the receiver without degradation.

What can UPCI do for you?

The AMM - UPCI will dramatically improve audio reproduction and recording quality, no matter if you use consumer, professional or high-end equipment.


    A $99 CD-player used with AMM - UPCI and external DA-converter will give comparable performance to a $10.000,- CD-transport, used with the same DA-converter but without AMM - UPCI (no, its not a joke).

    The same applies for DAT and DVD players.

    Any high-end CD or DVD-transport used with AMM - UPCI will be drastically improved in sound quality.

    Any external DA converter will be drastically improved in sound quality with AMM - UPCI and will be more independent from the quality of the transmitter.

    Optical Toslink connections will deliver excellent sound quality (even over long distances), when used with AMM - UPCI.

    The AMM - UPCI will improve the sound quality of stand-alone CD-players that have a digital output & input (f.e. Accuphase DP65V).

    The AMM - UPCI will improve digital recording quality of an externally clocked AD converter.

    The AMM - UPCI will improve the quality of asynchronous sample rate conversions.

The AMM - UPCI can be used to convert between interfaces while attenuating jitter:

Conversions are possible from:

ST optical
S/PDIF (coax)
S/PDIF (coax)

Update 11/21:

We were able to improve the UPCI's filter to previously unattainable performance. The new filter is included in the UPCI MKII which is now shipping.

Additionally, on the UPCI MK II the original Toshiba Toslink receiver is upgraded to a new version that is capable of transmission lengths up to 100m using standard plastic fiber cable.

Where to buy UPCI?

The AMM - UPCI is manufactured by Altmann Micro Machines in Germany and can be ordered by email.

Altmann Micro Machines
Erlenstr. 15
D-42697 Solingen
Phone: +49-212-233 7039

The AMM - UPCI is covered by a 5 years limited guarantee.

The price is EUR 1200,- RCA and TOSLINK models.

Prices include world-wide shipping to your location.

European and Overseas orders are shipped via premium air parcel, insured.

Please specify the desired sampling frequency and input / output type.


Text (c) by Charles Altmann