Axiom Home Page Forums General Discussion Home Theater Oppo 103 audio processing

Brendo, you dont need to have your subs placed the same distance to your mains, but you would need to be able to delay (advance them stricktly speaking) them independently to align them properly. The newer Denons allow different settings for delay and trim for 2 subwoofers for example. You are really only able to do this for one point in space, and over a narrow band when aligning to mains.

Without independent delay the subs can be aligned to eachother physically by placing them equidistant to your position AND the mains. Otherwise cancellation with one channel or another. Symmetrical setup is really the best to deal with this.

The newer subs probably have less lag than my older svs subs. It would be interesting to see how the Axiom subs behave. It wouldn't surprise me if they were a little better, but probably all powered subs are 20ms or so behind their smaller passive speaker counterparts. If your AVR auto cal sets the sub distance wierd (long) this is likely whats its trying to correct for.

In case that read confusing here is how you would do it without independent delay. I even found an Axiom example.

The delay in the EP800v4 appears to be about 7 or 8 msec at 80 Hz. As Trevor said, the time delay, polarity and phase settings are critical. A difference of 5 msec results in 10 dB of attenuation at my MLP. Ditto with incorrect polarity and phase.

My mistake...the processing delay in the EP800v4 is about 5 msec at 80 Hz.

Thank you for all your knowledge on these REW type details guys.

Having an Anthem Mrx720 I'm still not sure how they deal with subs.
Followed their instructions {set subs SPL to 71 for dual EP500\SVS PB1000} should get them to 75DB. paired. Though I don't think they are treated separately as Denon does.

To Trevor would the Phase adjusting method you explained to us around a year or so ago, Raising the sub distance to the highest SPL. Still be effective in this situation? Or would it just add more delay?

Mojo is finding the 1/4 wave pattern. Guaranteed the latency is greater than 5msec. The reason I know this is he is quoting a frequency. But he is spot on anyway.

The sine wave vs spl test will get you perfectly time aligned but wont account for phase alignment. Strictly speaking, phase alignment requires transfer function measurements, smaart live or equivalent. I dont know if REW does it. I use audiotools. Phase alignment is both onset of transient and cycle alignment. Uber aligned.

Dont despair! Getting a max spl at the low pass setting is dang great! I messed with some stuff today, but the full show and tell needs a little more time. I just got the 2x4 but still boxed up. Tomorrow maybe. Libations for now!

The oppo 103 has severe clipping problems when you set the speakers to small and implement subwoofer bass management. When a strong input signal is sent out the channels distort horribly, even at low listening levels. This is a problem on oppo's end that they didn't seem to be able to resolve I guess. Not good!!

set speakers small
crossover 60hz
debussy invocation off stereophile test disc as example. clipping more than a barber shop.

I had initially thought it was the introduction of the minidsp2x4, but the issue persisted when I removed it from the chain. Resorting back to letting the AVR send signal to the outboard amp from preouts solved the issue. Thank goodness it wasnt the amp!!

-1 for oppo. Not very good guys. frownie face! I was a pretty big fan. Little disappointed now.

And it seems the 2x4 drops the input signal enough that without reducing trim it causes a net loss of 7db in room! Cough..... How the heck is this not something people mention?!

So, maybe for subwoofer eq? Would be fine if you didnt need to reference it to other channels. Dont expect a write up on this one.

Edit: yep. Insertion loss in signal path. So both the oppo and 2x4 have gremlins.....

https://www.minidsp.com/forum/hardware-support/1338-re-minidsp-output-volume-voltage

pulling it apart to change the jumpers now....

It's unfortunate (or fortunate depending on your perspective) you found these problems. I wonder now what my Onk's pre-outs are like.

I don't know what you mean by the quarter wave pattern. I wanted to make sure I minimized a null in SPL at my MLP at the 80 Hz crossover. In my Onk, I set the distance between my sub and the MLP, secured the meter at my MLP, and established the correct polarity by playing an 80 Hz sine tone. I set the polarity such that it resulted in the highest SPL. Then I increased the distance setting until the SPL went to a maximum. Finally I adjusted the phase to ensure a maximum SPL. My phase is set to about 60 degrees. I saw no difference in SPL between 0 to 60 degrees. After 60, it started to dip. Coincidentally, one of my fundamental room modes is at ~80 Hz due to my ceiling.

My sub is 9 feet away from my MLP. The distance setting that resulted in the highest SPL was 14 feet. I thetherefore had to add 5 feet to account for DSP processing delay. This is about 5 msec at 80 Hz.