TOPIC:

There was a discussion more than a year ago on that subject. Unfortunately I don't find the post any more.

As agreed in that post, my power supply is not the problem. The moderator commented, that the DDRC-24 had a problem at low temperatures which was supposed to be fixed. The team wanted to look at the issue again. But no feedback so far.

Temperatures are now below 5 degree C and it takes minutes for the audio to come up.

Can you help?

I too would appreciate an update on this, and posted in the older thread.

I have around 10 DDRC24s in service and all suffer from this problem to some degree.

Unfortunatley, I never got a reply back from miniDSP regarding my issue.

After about 4 years of living with the issue of audio coming on delayed in my car at temperatures below 15 degrees C, I took a closer look at the design of my miniDSP 2x4 HD which I had upgraded to DDRC-24. The H/W version is R1.2, Jun 06 2016.

Using cooling spray, I could identify a certain transistor, that causes an audio mute when cooled down. The suspicious transistor is shown in the attached overview picture.

I then looked at the circuit around this transistor. See attached detailed view picture.

At room temperature, the voltage at the collector is at about 9.9V and audio is unmuted.The base voltage is at about 0.53V (pretty low to switch on a pnp reliably). When cooling the transistor down, the base voltage does not change, but the collector voltage goes up to about 10.9V and audio mutes. This means that either I have defective component somewhere or the design is flawed. I know that miniDSP changed a resistor somewhere to solve this known issue, but at least in my case without success.

To solve the issue, I connected a 220k pullup resistor from the base of the transistor to the 5 volt of the close by 5V regulator (see overview picture). With that, the collector voltage was not that temperature sensitive any more and did not reach the critical 10.9V. Even with the transistor completely iced, audio did not mute any more.

During my tests with the modified circuit, I could not detect any negative influence of my modification.

I would be interested in miniDSP's comment on my findings.

Another subject not related to the thermal issue:
In my car, I sometimes don't get any audio when starting the car and with that power up the DDRC-24. Powering down and up does not fix the issue.What I found is that if I connect the DDRC app via USB to the DDRC, the Mute icon is 'on' (i.e. red). When I turn mute 'off', audio starts playing.Why does the DDRC come up muted sometimes without being told to do so? Has anyone experienced the same issue? 

martin.hoeer wrote:

In my car, I sometimes don't get any audio when starting the car and with that power up the DDRC-24. Powering down and up does not fix the issue.What I found is that if I connect the DDRC app via USB to the DDRC, the Mute icon is 'on' (i.e. red). When I turn mute 'off', audio starts playing.Why does the DDRC come up muted sometimes without being told to do so? Has anyone experienced the same issue? 

Hi Martin,

Thanks for your post. I have exactly the same issue regarding randomly starting up muted. I use the car every day, and usually the remote will be able to unmute the output, if it comes up muted, but about once every couple of months it will not unmute via the remote and a USB connection to reset the configuration will be required.

Also would welcome any insight into this issue that others might have.