Axiom Home Page Forums General Discussion Home Theater Please weigh in on crossover settings

What would you recommend for this 5.1 setup (70 percent music, 30 percent movies):
Fronts M80 HP
Center VP180 (non-HP)
Rears M22
Sub EP800
Amp Rotel RMB-1575

Rear at 80 is obvious. Question is front array with these possibilities:
80 80 80
60 80 60
60 60 60
40 60 40
Thoughts please? Thanks.

Also, I have “original” EP800. If anyone possibly knows, curious about the subsequent changes? Just amp programming, or actual different amp and/or physical change to drivers?

I have the 800v4. I know the amp is definitely different than the original that Tom Cumberland engineered. Besides the continously adjustable phase control and the lack of a USB port, I don't know what all the differences are. Andrew also got rid of the room gain knob which was nothing but confusing for me. I bet the DSP code is better (lower distortion, etc), the firmware and hardware more robust and reliable and it just plain sounds better than the original. I also think the drivers and cabinet are much improved. I am taking mine to my grave. I lived with the curse of the 600v2 for 11 years and thank Ian that a year ago he let me trade in for an 800v4. The v4 DSP subs are simply amazing. You might want to consider trading yours in for a 600 instead of an 800 if cost is an issue.

Geez, that looks like a nice amp. Congrats! It's tough to make a call on what sounds best for cross-overs because it depends on room, ears and gear. I've found my system sounds best with the 160v4 and QS10HP at 40Hz and M5HP at 80Hz. My Onk's Audyssey XT32 found them all at 40Hz by the way.

without any knowledge of your dimensions, processor or listening level all I can say is that a higher crossover setting will allow greater phase adjustment relative to the main channels.

Higher crossover= shorter wavelength= more possible relative delay (phase rotation)

To better understand your answer did some further reading and came across this:
https://jlaudio.zendesk.com/hc/en-us/art...obile_site=true
A similar situation exists with home theater (e.g. “surround“) setups where the customer thinks that the front speakers are ”full range“. Even so, the best approach is to seal the ports, operate the 5 channels as ”small", crossover at 80 (or even a bit higher, but never lower) and correct the timing issues inherent in all modern subwoofers by setting (in the receiver or processor’s setup menu) all the distances the same, and to a small number such as 7 feet; then set the subwoofer to 12 feet more (i.e. 19 feet) and then use the variable phase control on the subwoofer to fine tune the relationship at the 80 Hertz crossover point.

Bang on!

The only thing I would caution is the phase control knob on the back of a subwoofer isnt really an accurate solution. It is not as granular an adjustment as the actual distance setting in the processor. Also, a phase knob on the subwoofer can only retard its position in time relative to other channels, not advance.

In a 5.1 setup, set all your speakers to 80hz. You would need fantastic bass from the M80's and a really bad sub (not the case for the EP800!) for 40hz to win.

I'm reminded every time at how good the EP's are when I cycle through sound modes and hit direct and my L/R go full-range and the sub is turned off. Let the sub do what it does best.

This is how I solved the problem of standing waves with my M3s and yammie sub in my living room. I stuffed the sphincters of the M3s with foam. All issues disappeared without using any EQ.

I don't understand where he gets the numbers of 7 feet for speaker distance and 19 feet for sub distance. Those must be examples.

You stuffed the gorilla rectums with foam?

Oh hell not me, Phil. I'm scared of those damned things. I had one of my fem friends stick her delicate, little hand in there. She actually quite enjoyed it!

I stuffed the M5s and the 160 with foam in my main room and cut all speakers to 80Hz. I'm even more close now to not needing Audyssey. I have a very narrow band somewhere down low I need to knock down.

Incidentally, even with the sphincters plugged, the Onk found all my speakers at 40Hz which I find very surprising.