Diagnostic assistance needed


#1

I had an event happen recently that I wanted to get some assistance with. I have a DirectStream DAC and Memory Player. The DAC goes into a Linear Tube Audio MZ2 preamplifier that drives a Linear Tube Audio Ultralinear amplifier. I was playing an SACD of Mahler’s 2nd symphony. This is a very dynamic sacd. Near the end of the symphony right at the climax, the music stopped and instead I got a very high pitched siren sound coming from the speakers-it sounded as if my alarm had gone off in the house-it was scary cause I was afraid this siren like sound would blow my speakers, though they appeared okay after this incident-the sound went away when I turned down the volume knob on the preamplifier. I have played that cd since, only on my headphone system to see if I could duplicate the sound-the cd has played without this happening again. I also have played other cds on my primary system without incident. My assumption is that the preamplifier got overloaded-it does not have a protection circuit, though the amplifier does. The only other new variable was that I did install a new interconnect prior to playing that cd. The other odd thing about this is that right after I turned down the sound on the preamplifier I tried to open the drawer on the memory player and it would not open-it had frozen up-I had to push the reset button on the back before the drawer would open.

Obviously I would like to not have this happen again-any recommendations and advise would be appreciated.


#2

Try turning the volume down on the DAC; the output level may have saturated the preamp’s input and caused it to go into overload. So drop the output of the DAC from wherever it is (default is 100, I think) to, say 80, play the passage, and see if it trips into overload again at the same volume level you had set on the preamp the last time.

If not, the incrementally raise the volume of the preamp in small steps until you get it to the level you like. If it ever trips into overload, it means the ouput of the preamp is overloading into the amp (or the amp is overloading)

Anyway, try that first and report back.

Best of luck.

–SSW


#3

The fact that your Memory Player’s operation was frozen after this occurrence would lead me to suspect that it somehow malfunctioned and that its digital output to the DAC may have caused the erroneous signal output you heard. Just speculation on my part but if your MP has not similarly locked up otherwise I think it may be a valid hypothesis for further investigation. If it only happened once with that disc and you can’t replicate the problem it’s likely nothing to be concerned about and may have just been a rare glitch in operation as digital components can sometimes have.