Axiom Home Page Forums General Discussion Technical Questions getting more bottom end from sub

When I was listening to a Reggae CD (one song in particular) that I'm very familiar with and has a lot of bass. The bottom end was virtually nonexistent at one point in the song where it's just bass. I'm comparing my EP500 to my previous paradigm which had far less output but I noticed the bottom end. On Saturday I will be calibrating my system using a calibration DVD. Aside from the DVD calibration settings, what else can I do to improve the bottom end?

My Denon AVR3801 doesn't have a adjustable Hz setting on it. My front speakers are set to "small" which defaults the receiver to 80 Hz.

Going from memory the settings on my sub are as follows:

crossover-bypass
volume-between 8 and 9 o'clock
phase- 0
trim-flat

Try the fronts set to large and run the cd in direct mode. I noticed a little more low end running like this on my 1804, in stereo mode some of the low end disappeared.

With my fronts set to large won't it take more base away from my subwoofer?

Just going through my manual. On my denon should I have my LFE setting set to just LFE, or LFE + Main? It says when LFE + Main mode is selected, the low-frequency signal range of channels set to "large" are produced simultaneously from those channels and the subwoofer channel.

This sounds like the optimal setting. Can anyone else clarify this?

Thanks

You are getting the LFE channel plus all bass to your speakers set to large and the sub. This setting helps to even out the LFE in the room, IMO.

Thanks for your help Jason. In the manual it says exactly that. It was suggested by a Axiom representative to set my left/right channels to small. I think I will try setting them to large as you suggested and changing the LFE to LFE + Main.

Any other input would be greatly appreciated.

You got it right. With the fronts set to large and the sub set to LFE+Main, you've got all the front bass going to both the fronts and the sub.

I am running my M80s as large and LFE as norm which means the LFE channel and all signals below the xover of speakers set to small is being sent to the sub but everything except that in the LFE channel is sent to the mains.

Welcome to the world of peaks/nulls in a room. Most likely your dealing with sub placement a room acoustic issues. Personally, I still would recommend using the small settings and let the sub do the work it should be doing as it can move more air.

Sub placement, especially with only one sub, can be a long life struggle. Room treatments, correct sub placement, room dimensions, etc. are just a few links in the chain.

I'll have to look at your pictures again to see if I can come up with any further suggestions.

Thanks for the help. I don't really know where else to place my subwoofer.

For your convenience, here's the link to the pictures of my room.

[url=]my room[/url]

The 500 can definitely pressurize that room. In my space, it makes no difference whether I have LFE or LFE+main. Try this however. Dial your 500 to about 7 o'clock and 40Hz. Set your trim to full. Set the Denon's cross-over to 40Hz (the 3801 should have this...I have the 2105 and it has it). Then set the Denon LFE gain to +3. Set the sub's distance to 5 feet greater than actual. And don't forget to experiment with the phase switch. I have a whopping 14dB difference in my room that is phase switch dependent. Use and SPL meter to judge this. Let us know how it sounds. Also check to see that the straps on the back of the 80s bridge the woofers too.

I would also try the sub crawl to check for the best placement but with your room setup you will most likely end up up where it is unless you rearrange the room.

Wow...

I have just left the phase switch on my 500 set to 0.. largely because I don't know exactly what it does. Maybe I should experiment with that too.

Mojo, I am not sure about other denons but on my 3808 the LFE channel can only be adjusted from -10db to 0db... ?

My Denon 3801 doesn't have a adjustable cross-over. When the speakers are set to "small" the receiver cross-over is set to a 80 Hz default. I also just looked in the manual and it doesn't say anything about adjusting the LFE. I am assuming you mean setting the subwoofer to + 3 dB when I run my "test tones"? The only adjustments I have for bass output are my "test tone" settings, and the "tone control" which adjusts bass and treble.

Here is a link to Denon's web site where you can download the manual for my receiver. I assume it will help with suggestions on setup because it's an older model and everyone is different.

manual

Thanks again for everyone's time.

Axiom probably recommend you to keep your front speakers at small to keep the demaning load off your Denon and transfer it over the EP500.

It takes a lot more energy to produce low frequencies than high ones. If you set your fronts to large and LFE to both main and sub, your Denon amp will have to work that much harder to reproduce low frequencies to your main's (M80’s). That seems silly when you have a 500 watt amp in your EP500. It’s all about adding headroom for your amp to prevent clipping.

When you go to a monster receiver or separates and have 150w/c or more to play with, then there is more headroom for your amp, and you can set the mains to Large and LFE to both.

Your M80’s are capable of handling tremendous levels of low frequencies, but you amp may not. It’s all about headroom and not clipping!

Paul

the 3808 has 130wpc and I have my my m80's set to large with the the sub set to LFE +main. I have not had a problem with dynamically demanding scenes or music yet. IF I do, I will change the mains to small and the sub to LFE only.

for now, I like having the low end comming from both the m80's and the 500.

I agree 100%, I bought the M80's because I wanted a full range speaker. If I was going to set main speakers to small, I should/would have bought the M22's.

130 watts is lots of power depending on the size of room and how loud you like to listen to music. You should have lots of headroom to play with.

I like having the LFE comming out of both too.

Paul

There's no worries of clipping. My RPA-1 powers my M80s.

Here's my attempt at explaining phase. Look at this simple waveform:



The horizontal line represents the speaker cone when it is at rest. Anything above the line tells the speaker cone to move outward. Anything below the line tells the speaker cone to move inward. As we all know, speaker cones move back and forth creating varying pressure waves that radiate out into the room and eventually reach our ears.

The phase characteristic of sound is basically the position or orientation of the waveform with respect to some point in time. In these examples, the reference point is the vertical amplitude axis. Now, with only a single sound source, the phase makes no difference. You can move it 90 degrees:



or 180 degrees:



and it will make no detectable difference in the sound you hear. Where phase starts to matter is when you have more than one sound source in your room. Watch what happens when you have two sound waves and one of them is 180 degrees out-of-phase with the other:



Notice that there is an equal amount of signal above and below the line. When you add them up (as your ear would do), the result is absolutely no sound. Keep in mind that this is an idealized situation and rarely do you ever get a complete canceling out of sound in the real world. Usually you only get partial canceling, as would happen if we were 90 degrees out of phase in this example:



But how does this all apply to the phase switch, and why would you ever want to use the 180 setting? The answer is that it all depends on the arrangmeent of your speakers. The reason you don't have to worry about adjusting the phase of your two main speakers is that most people arrange them so they are both the same distance from their ears. The sub is often placed somewhere else, often much further or closer to the listener's ears than the main speakers. The phase switch allows you to compensate for the unpleasant sound cancellations or reinforcements that may occur in the bass range that exists within the crossover thresshold between the sub and the main channels.

I probably could have worded this better, but it's lunch time now and I'm hungry.

Wow, that's pretty good, Peter! I've always liked subs that have a variable phase knob rather than a switch.

Your pictures really help explain what's going on.

Thanks for the explanation.

I ignored most of the AC circuit 'phasor' stuff we talked about in my ENG physics II and circuits class. It was my opinion at the time that all of that mumbo jumbo should be left ot the Electrical Engineer.

Being that my subwoofer is up front with my mains, a 180 phase adjustment may not be what I need. I will still experiment with it though.

Thanks. Photoshop is good for more than messing with photos.

Yes, I still need to get you back for that one. In all fairness, the angle wasn't right and my bride's natural beauty was somewhat diminished.

Cam,

I looked at your manual. It really sucks that you can't change the x-over frequency. I would suggest you experiment with setting LFE+main and then dialing the sub to 60Hz and 40Hz. Also, "play" with the phase switch. And remember that the bass you heard with the Paradigms may not even really exist because the Paradigms may not have been flat.

I'm sorry, you know I'm new to this. What you mean by "dialing the sub to 60 Hz and 40 Hz" and how to why accomplish this? I'm really trying to get as many suggestions before tomorrow. Mojo knows, that I am bedridden the majority of the time and can only get up periodically, so that's obviously when I like to enjoy my home theater.

Thanks everyone

Mojo is talking about setting the dial on the back of the sub to 60 or 40hz while the LFE + main is selected this way you can adjust when the sub comes on using the subs built in cross over. I don't think the phase switch you need to worry about right now.

That's exactly what I'm talkin' about. Unfortunately the Axiom subs are not "wheelz-friendly". A remote control would have been a necessity in your case. Too bad one of us didn't live closer to help you out.

He's just a short drive and it is the weekend. Ok not so short a drive but if I was heading even remotely that way I would be there.