Conversation transcription cannot be started using a 7-mic array

Question

Hi,

A 6+1 mic is required for conversation transcription. I am using this mic (https://www.minidsp.com/products/usb-audio-interface/uma-8-microphone-array) that meets the requirements stated for a 6+1 mic type (https://learn.microsoft.com/en-us/azure/cognitive-services/speech-service/speech-sdk-microphone).

I am using C# Speech SDK 1.24.0. Everytime I try to create a ConversationTranscriber instance I get the following error:

System.ApplicationException
HResult=0x80131600
Mensaje = Logic error: Single channel audio configuration for ConversationTranscriber is currently under private preview, please contact diarizationrequest@microsoft.com for more details
Origen = Microsoft.CognitiveServices.Speech.csharp
Seguimiento de la pila:
en Microsoft.CognitiveServices.Speech.Internal.SpxExceptionThrower.ThrowIfFail(IntPtr hr)
en Microsoft.CognitiveServices.Speech.Transcription.ConversationTranscriber.FromConfig(GetTranscriberFromConfigDelegate fromConfig, AudioConfig audioConfig)
en Microsoft.CognitiveServices.Speech.Transcription.ConversationTranscriber..ctor(AudioConfig audioConfig)
en MedConTest.MedConTranscriptor.TranscriptConverstation() en C:\Users\jcastejon\Projects\MedConTest\MedConTranscriptor.cs: línea 31
en Program.<Main>$(String[] args) en C:\Users\jcastejon\Projects\MedConTest\Program.cs: línea 5

The mic is configured as raw with 8 channels:

This is the code snippet:

 var speechConfig = SpeechConfig.FromSubscription(KEY, REGION);  
 speechConfig.SetProperty("DeviceGeometry", "Circular6+1");  
 speechConfig.SetProperty("SelectedGeometry", "Raw");  
 speechConfig.SetProperty(PropertyId.Speech_LogFilename, LOG_FILE);  
 speechConfig.SetProperty("ConversationTranscriptionInRoomAndOnline", "true");  
 var conversationTask = Conversation.CreateConversationAsync(speechConfig, "Test");  
 conversationTask.Wait();  
 var conversation = conversationTask.Result;  
 var audioConfig = AudioConfig.FromMicrophoneInput("{0.0.1.00000000}.{38befb85-146f-48a2-b93c-c07c7bd1abc1}");  
 var transcriber = new ConversationTranscriber(audioConfig);  

Is there anything wrong either in the code or with the mic?

Thanks in advance!