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--- xrvsmr [2024/06/17 09:13] – created wadmin
+++ xrvsmr [2024/06/17 12:51] (current) – wadmin
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-==== XR18 vs MR18 ====
+===== XR18 vs MR18 =====
 {{drawio>xrmr:main.png}}
+==== Introduction ====
+This document proposes a test procedure and results comparing Behringer XR18 and Midas MR18 performance.
+==== Disclaimers and Claims ====
+Starting with a general statement: Measurements are done as close as possible to what would be a scientific measurement process (Configuration and tests are documented, are reproducible by a third party, tests results are published, known assumptions and limitations are mentioned as far as possible).
+Now the claims:
+  * **Statement #1** : Measurements are done in recording studio environment. Namely, there is no control on CEM/EMI interfering with measurements apart from standard studio installation best practices in terms of proper ED grounding and shielding.
+    * As a consequence, comparing the results is more important that dealing with the RAW value.
+  * **Statement #2** : One input and one output are used on each unit, there is only one pair of interface sample tested. Having a pair allows to check for a similar performance on both interface, to rule out obvious erroneous failures on one interface. It is understood that statistically processing those measurement among several interfaces and unit S/Ns would be much better, but is out of scope of this measurement procedure.
+    * As a consequence, these results are (1) immune to critical failures on one channel but are (2) prone to specimen bias.
+  * **Statement #3** : XR18 has two high impedance instrument inputs which MR18 does not have. For the sake of comparing apples with apples, Input 9/10 and Output 1/2 are used as references on both units.
+Measurement Gear
+  * UUTs
+    * MR18 S211000533C8H
+    * XR18 **XXXXXXXXXXXX**
+  * Tools
+    * Gen2 Apollo Twin USB
+    * XLR Wires / Jack Adapters
+    * Room EQ Wizard Rev xxx for measurement
+-------------
+===== Test Procedure =====
+==== T1 - Inner Noise and THD ====
+Measure loopback  RTA THD (+N) @1khz + total dynamic range.
+=== Setup ===
+  * REW in loopback mode,
+  * Double shielded XLR as connection
+  * on both units, use In-9 and Out-1
+Loopback diragram:
+{{drawio>xrmr:t11.png}}
+=== *R18 Measurement ===
+== -12dBfs / G=0 ==
+  * Set Inputs Gain to 0dB
+  * Set Output level to match a -12dBfs input level
+  * Measure RTA and store
+== -12dBfs / G=8dB ==
+  * Set Inputs Gain to 8dB
+  * Set Output level to match a -12dBfs input level
+  * Measure RTA and store
+== -12dBfs / G=18dB ==
+  * Set Inputs Gain to 18dB
+  * Set Output level to match a -12dBfs input level
+  * Measure RTA and store
+== -12dBfs / G=28dB ==
+  * Set Inputs Gain to 28dB
+  * Set Output level to match a -12dBfs input level
+  * Measure RTA and store
+-------------
+==== T2 - External loop comparison ====
+=== Setup ===
+{{drawio>xrmr:t21.png}}
+=== *R18 Procedure ===
+== -12dBfs / G=0 ==
+  * Set Inputs Gain to 0dB
+  * Set Output level to match a -12dBfs input level
+  * Measure Transfer function and store
+== -12dBfs / G=8dB ==
+  * Set Inputs Gain to 8dB
+  * Set Output level to match a -12dBfs input level
+  * Measure Transfer function and store
+== -12dBfs / G=18dB ==
+  * Set Inputs Gain to 18dB
+  * Set Output level to match a -12dBfs input level
+  * Measure Transfer function and store
+== -12dBfs / G=28dB ==
+  * Set Inputs Gain to 28dB
+  * Set Output level to match a -12dBfs input level
+  * Measure Transfer function and store
+===== Test results =====
+==== T1 - Inner noise and THD ====
+=== XR18 Results ===
+== -12dBfs / G=0 ==
+== -12dBfs / G=8dB ==
+== -12dBfs / G=18dB ==
+== -12dBfs / G=28dB ==
+=== MR18 Results ===
+== -12dBfs / G=0 ==
+== -12dBfs / G=8dB ==
+== -12dBfs / G=18dB ==
+== -12dBfs / G=28dB ==
+==== T2 - Transfer function ====
+=== XR18 Results ===
+== -12dBfs / G=0 ==
+== -12dBfs / G=8dB ==
+== -12dBfs / G=18dB ==
+== -12dBfs / G=28dB ==
+=== MR18 Results ===
+== -12dBfs / G=0 ==
+== -12dBfs / G=8dB ==
+== -12dBfs / G=18dB ==
+== -12dBfs / G=28dB ==