Amp doesn't detect EX signal


Standard Member
I've just recieved my new Pioneer VSA AX10 amp and have been trying out DVDs with different sound formats.

All sound formats worked and were detected in auto mode apart from DOLBY DIGITAL EX. The amps instructions say that when the amps in THX auto mode it will automatically select THX EX mode when a DOLBY DIGITAL EX signal is detected.

DOLBY's web site states that all titles released after late 2001 have the flag signal to switch amps to EX mode.

Pioneer says that my DVD player (747A) will output DOLBY DIGITAL EX and DTS ES matrix/discrete signals.

The films I have tried with DOLBY DIGITAL EX are R1 Cast Away, R1 Blade II, R1 Monsters Inc.

Does anybody know why I am having this problem


Distinguished Member

Unfortunately most discs don´t have the EX flag encoded on them. It´s best to leave the Auto Flag Detect mode OFF and just manually switch on the Surround Backs when you watch an EX/ES film.

R1 Blade 2 is in DTS Discrete 6.1 so you want to be watching that rather than the Dolby EX track, its much better.;)

Quite a few DTS ES (Discrete & Matrix) tracks have the flag though.


Active Member
Hi Keif,

I have the same amp and problem. I have tried to set up the signal manually. It says on the display Thx Surround EX but there is no signal that the back speaker is working.
So I tried it on DTS-Es on gladiator, again the display says DTS-ES but there is no back speaker signal.
Thanks for Jase,s help but still cant crack the best format that I couldnt wait to hear.
Tomorrow I will disconnect one of the back speakers and try with one only. The display has never come up with DD-EX, cant get that at all. Perhaps it is looking for THX only because of the 2 back speakers.
I will have another go tomorrow to see that wonderful light saying back surround speakers are there.
I have got 747 as well.
If you have any ideas Kief let me know and I will tell you my finding,s.


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