Hi pg13,
I have exactly the same speakers (Orb People's choice 5.1) and receiver (Yamaha 663) as yourself, both of which I bought a couple of months ago.
1. Orb website says that I should not drive any speaker level to oustide +/-2db regardless of what the automatic calibration comes up with. My Yamaha YPAO comes up with driving the surrounds at +4db and sets the crossover to 160Hz. I manually changes everything to fit into +/-2db and 120Hz crossover. Cant point to the cause but the whole system sounds good but not great especially at lower volumes (typical listening volume for me is -34db). Why does Orb have that advisory ?
I'm pretty sure that Orb gives this advice because they're worried you might overload (and damage) a particular speaker. For example if you had one speaker set much higher e.g.+10db, then you might accidentally overload that speaker when you have the volume set really high. I wouldn't be too concerned about a setting of +4db though, I think that would be fine, it would be normal for your surrounds to be set louder than your fronts, because your surrounds are Mod1 and your other speakers are Mod2. Maybe check with Orb support just to be sure, their email support is very good, just check on their website for the email address.
Oh, and the 120Hz crossover is what I'm using as well.
2. The sub though nice is not "thumpy" enough. It hardly ever gets loud even in major action sequences. It is already set to +1.5db.
Firstly, double check what the volume setting on the back of your sub is. It should be around half (i.e. 5) but you could always make it a bit higher. And while you're checking those settings, double check that "X-Over" is set to Disabled.
Secondly, you could try putting the sub in the corner of the room (I'm not sure where you've got it at the moment), I think that normally increases how loud the sub seems.
Thirdly, you could always simply increase the level of your subwoofer in the receiver above +1.5db, by going into manual setup. Although you've mentioned Orb advises to stay within +/- 2dB I don't think this is as critical for the sub, I think that's mainly referring to the other speakers.
3. What exactly is the difference between mod2 and mod1 besides volume ? Given that I hardly ever go higher than -20db on my mod2 fronts, do I really need mod2 fronts+center ?
I'm wondering the same thing. I tried turning my front speakers into Mod1 (by disconnecting the wire which connects the lower speaker to the upper speaker). Personally I found that the effect was very slight, except that the volume was a bit lower. I have heard that a Mod2 will give slightly more bass output compared to a Mod1 but I couldn't hear much difference. Apparently its a good idea to leave the centre speaker as Mod2, because that's where most of the dialogue is for movies. So the answer is you probably don't need the Mod2 for your fronts, but I'd keep it for the center. Try it out and see what you like!
4. Any suggestions on receiver setup to get better performance at *low* volumes especially for music ?
You could always try the "ADAPTIVE DRC" feature on the amplifier, see if you like the sound of that. That feature is designed for listening at lower volumes.
Personally I found that my system was not giving enough bass (especially in music), which was especially noticeable at low volume, so I made some changes using the equalizer. In manual setup, under the sound menu, then Equalizer, "Auto PEQ" refers to the settings that were found during the YPAO auto setup. I changed this to "GEQ", which allows you to manually adjust the equalizer. For Front Left and Front Right, I increased the two lowest frequencies (63Hz and 160Hz): 63Hz +4db, and 160Hz +3db.
A few other settings just to double check:
- in manual setup under "Basic Menu", then "Speaker Set", check that all speakers are set to "Small", and that "LFE/BASS OUT" is set to "SWFR". You can also try changing "Subwoofer phase" to whichever value sounds better to you.
- in manual setup under "Basic Menu", then "SP DISTANCE", check that the speaker distances look correct, especially the subwoofer distance, I found this was sometimes inaccurate.
Hope that helps!
Chris