lkc_boot,
I think a small amount of chirp is normal before your DTS decoder detects the bitstream, but in your case perhaps you have a problem. I have an SP1.0 and all channels appear to mute during a switch (of any mode).
I think in general every manufacturer handles the problem of switching between bitstreams somewhat differently. My understanding is that in digital, the incoming SPDIF bitstream is constantly monitored so the decoders will know whether the appropriate decoding is PCM, AC-3 (2.0, 5.1 etc) or DTS of various flavors.
When the processors DSP's first receive or detect a change in the encoded material they immediately mute the volume controllers and the correct bitstream detection routines are enabled. You sure don't want to hear what comes out your speakers while this nonsense is going on - it can be very damaging to the speakers in some cases.
But there's a tradeoff (as there always is in electronics). A manufacturer is perfectly capable of holding the mute long enough and combine it with a soft volume increase, but then everyone would be complaining they had to wait too long until their decoders locked onto the signal. Alternately, if the volume controller is un-muted too quickly you will get a digital chirp. So, while some manufacturers equipment seems to take forever for a "mode" change, others hedge their bets and you get that digital chirp. My SP1.0 appears to take care of it perfectly, in my opinion.
In your case it appears your main left and right channels are muting properly, but not your center or rears. You could check if the muting feature is working by doing the following:
Turn on all 5 channel amplifiers and put your SP1.7 in DVD (digital mode).
Put in a DVD that has a DTS sound track (gladiator etc) and get it playing. You can put the volume on very soft because your ear will be right against your tweeters.
Then press pause. The DVD will pause and the SP1.7 display shows "DETECT" and all your five channels should be muted and the 'hiss' should be zero from all five channels.
Then press play and you'll see the video start, but the audio won't begin right away until the bitstream is detected and the volume controllers are unmuted. When they unmute, the hiss will be back and you should not notice any noise or chirp from
any of the five channels on that transition. You'll need your ear right against the speaker(s) to accomplish this test. If your rear and center are chirping and your mains are not, I believe you've got a problem...
brucek
