Mic Trim Noise?

[David Bleistein]

Hello out there? Has anyone had trouble with noise being added when you turn up the trim for a mic in channel A?

I have a an AT4033a that is perfectly quiet using a Blue Icicle XLR-USB adapter with my laptop. When I plug it into channel A of the DP-24SD, with 48v on, and turn trim up about 90%, I get between -36 and -3odB of white noise that sounds like AC or heater wind, but it is not. I know I can use Noise Suppressor, but the noise is still added when the gate opens.

Does that sound like a defect, or is that the way it's supposed to be? I'm pretty much ruling out room noise, as I have reduced all noise, AND see my laptop test above.

 

[Phil Tipping]

Hi David. My dp-32sd inputs all have a small amount of hiss at high trim settings, but it's the same across all channels. Haven't measured the levels though. Have you compared the actual gain amount with the other channels? It may just be a case that channel A has more gain so you're getting more apparent hiss. If not, then guess it must be a faulty pre-amp.

 

[David Bleistein]

Thank you, Phil. I will try that. I have also sent mp3 samples to Tascam on this. I'm waiting on their response.

 

[Phil Tipping]

One more possibility... which depends on how you are monitoring the inputs. If you are doing it by routing them to the stereo bus, there's an additional trim control level in the path which is only accessible in the mixer screen. It's normally set to 0, but it may have been set higher for input A. The control has no effect if you are routing the inputs to tracks (see block diagram)... just a thought.

 

[David Bleistein]

Thanks again, Phil. I think I've actually seen that control. Will check it out. I bought the unit in late July, 2016, so I have a lot to learn.