User`s guide

User's Guide ADI-8 DS © RME
7
6. Inputs and Outputs
6.1 Analog Inputs
The ADI-8 DS back provides 8 (stereo) 1/4" TRS jacks and a 25 pin D-sub jack. Both are
internally connected, so not operational at the same time. The electronic input stage is built in a
servo balanced design which handles monaural and stereo jacks correctly. When used unbal-
anced it automatically corrects the gain by 6 dB.
When using unbalanced cables with XLR jacks pin 3 of the cable's jack should be connected
to pin 1 (ground). Otherwise noise may occur, caused by the unconnected negative input of
the ADI's balanced input.
The 25-pin D-sub connector follows the pinout known from devices manufactured by Tascam.
Refer to chapter 10 for a pinout listing. We do not recommend to make such a cable by your-
self, as it is extremely difficult to integrate 8 balanced lines into a small D-sub housing without
shorts. Your dealer will be glad to provide you with a professional Tascam multicore, D-sub to
XLR, made in the length of your choice.
One of the main issues when working with an AD-converter is to maintain the full dynamic
range within the best operating level. Because of this RME's ADI-8 DS includes electronic
switches of the newest technology, which introduce no additional noise or distortion to the audio
path. The key INPUT LEVEL allows a perfect adaptation for all 8 channels to the most often
used levels -10 dBV and +4 dBu.
Each analog input has a 'Signal Ok' and 'Over' LED, so levels and Overload of each channel
are easy to check. The green LED begins to light at -40 dBFS in an analog fashion (more bright
at higher levels). When this LED lights up only seldom or never, the input level is too low, caus-
ing a noisy and distorted recording. The red LED lights up 2 dB before reaching maximum level
(-2 dBFS), to securely prevent overload of the analog input.
The 'standardized' studio levels do not result in a (often desired) full scale level, but take some
additional digital headroom into consideration. The amount of headroom is different in different
standards and again differently implemented by different manufacturers. Because of this we
decided to define the levels of the ADI-8 DS in a most compatible way. The headroom of
the ADI-8 DS is defined according to the chosen reference level.
Reference 0 dBFS @ Headroom
Lo Gain +19 dBu 15 dB
+4 dBu +13 dBu 9 dB
-10 dBV +2 dBV 12 dB
At +4 dBu a headroom of 9 dB offers a problem-free operation with most devices, and meets
the latest EBU recommendations for Broadcast usage. At -10 dBV 12 to 15 dB headroom are
common practice, each mixing desk operating at -10 dBV is able to send and receive much
higher levels. Lo Gain allows to work with high levels, best suited for professional users who
prefer to work balanced and at highest levels.