Onkyo SR600 rear center channel problem (1 Viewer)

[GregBe]

I know saw this topic in the past, but through extensive searching, I can't seem to relocate it. I have an Onkyo SR600, and finally will be upgrading the 6th speaker for the rear center channel. I am pretty sure that I saw that there was some specific problems with that channel on some of these units, and the thread listed a test to see if your receiver had this problem.
Any help with this info would be much appreciated

 

[Jeremy Anderson]

It was my post 'cause I discovered the problem, so I guess I might as well answer your question!

On some of the 600's (and apparently some other models), there was a problem with the EX decoding in which out-of-phase sound which should be sent to the left and right surrounds was just thrown out by the decoder. It's a minor problem that perhaps most people wouldn't notice, and I just stumbled upon it while running through some test tones.

To test for it:
1. Force EX mode to ON, not Auto. You can run this test without actually having a center surround speaker connected if you want by simply enabling it in the receiver's setup (so that the EX mode option becomes available).
2. Using any disc with THX Optimode test signals or a calibration disc such as Avia, play the phase test tones for the surrounds. This alternates in-phase sound and out-of-phase sound to the left and right surrounds.
3. What's SUPPOSED to happen in EX mode is that the in-phase sound should come from the center surround ONLY and the out-of-phase sound should come from the left and right surrounds ONLY. If, during the out-of-phase portion, your left and right surrounds are silent or only emit a slight hiss, then your unit has the EX phase bug. Call Onkyo and they should be able to instruct you on how to get it serviced.
4. If you're doing this with no center surround attached, run the phase test once with EX turned OFF so you can hear the level of sound that is supposed to come from the surrounds. Then run it again with EX turned ON. It will be pretty obvious if your unit has the bug.

Though it sounds like a very minor problem, it actually does make a big difference in the cohesiveness of the rear soundstage. Newer models shouldn't be affected by this problem since Onkyo now knows how to test for it, but it never hurts to check!

 

[GregBe]

Jeremy,

I was curious if you knew what the out of phase information that is being thrown out actually is. Is it something that is being directed to the wrong speaker, or is there a lot of info that is just not there.

The reason that I ask, is that I have been going around and around with this issue for 2 months now. First, the part that came in to the local service center did not work. The part was reordered and it did not work again. The 3rd time an entire board was ordered, and was repaired and I picked up the 600. I tested the unit, and it had the same exact problem.

Now Onkyo wants me to send it to a regional service center in Utah with a 2-3 week turnaround time. I am wondering if it is even worth it at this point. I believe Dolby said it wasn't a big deal, but you had mentioned that it is.

Thanks
Greg

 

[Jeremy Anderson]

Well, it essentially throws out any sound that is exactly opposite between the left and right surrounds (i.e. out of phase). This sound should be left in the left and right surrounds when EX decoding is engaged (whereas in-phase sound goes to the center surround), but units with the phase bug are cancelling that sound out for some reason. While Dolby told me that it wouldn't be noticable, my personal experience (and that of others) is that there IS a notable difference in the rear soundstage once this problem is fixed. Could I tell you exactly HOW it's different? No... but I can tell you that the overall sound of my system sounded WAY more coherent with the properly working unit. I had both a working and non-working unit simultaneously, so I was able to alternate between them for comparison.

Is it a MAJOR problem? For most, probably not. For people without a center surround attached, DEFINITELY not (because the problem is only in EX mode). But to me, if I pay that much for a receiver, I want it to work 100% to specs. It's ridiculous that they've kept you without a receiver for that long.

 

[GregBe]

Thanks Jeremy,

As much as I just want to move on, it is driving me nuts that my receiver isn't 100% what I paid for. I guess I will send it off and get it repaired. Thanks for your help in bringing this problem to my attention.

Greg