A funny thing happend when doing the DS bit perfet test.

Using FPGA 6115 and DAC version 1.1.7 when doing the bit perfect test. I am using the Bridge. The DS screen displays a green tick and says Bit Perfect , then , underneath BitPerfectTest 24 96. All good IMHO. However, when the test is running there is a strange noise coming out of my speakers. The best I can describe the noise is an EE-OR like an emergency vehicle siren only not very load. I tried 1.1.9 with no change. I did this when I first became aware of the BP test. I didn’t hear it then.

Any ideas?

The BitPerfect test description say’s that you might want to mute before you run. The noise is a PRNG superimposed on a very low frequency triangle. Altho we might be able to mute a good bitperfect test after a second or so, if the bit perfect test fails the DS wouldn’t have any idea that you are even trying :slight_smile: If you have a DC coupled system you definitely do want to mute it.

Thanks Ted! I still have that shed out back if you wanna take a holiday Downunder!4_gif

By DC coupled system am I correct in assuming that means direct to amps? I’m kind of like Homer Simpson when it comes to understanding, well, just about anything!

Some preamps and some amps have DC blocking filters. They can protect the devices from horrible thunks and other problems, but on the other hand it’s hard to make a DC blocker that doesn’t somehow affect the sound. You have to check your manual.

On the other hand pressing mute on the DS remote or screen before you run the bit perfect test is easy and safe.