Axiom Home Page Forums General Discussion Stereo Out with the new and in with the newer

Mojo, I know this. Running the jumpers from the speakers to the sub ensures you are getting proper phase easily.

In fact, doing so with the subs next to the actives, driver facing the same direction as the triple 6.5's, will make for a full range, flat to 17 Hz, phase correct system.

A great disc to demonstrate what the EP can add would be on Steely Dan's 2 Against Nature CD.

The 2nd track has a 16 Hz synthesized kick drum that hits both 16 and 32 Hz.

With the EP800 in the system, the deep bass ripples through you. Take the sub out, and you still get the 32 Hz hit, bit without that ripple effect that 16 Hz adds.

You are experiencing what you are due to a lack of content below the mid 30's.

A properly dialed in sub should be unnoticeable until the rare time you get bass in the 15 to 30 Hz range.

Your content and upstream equipment may have you in a position in which a subwoofer doesn't add much.

Craig, very valuable input. Thank you.

Even if the sub is jumpered as you say, the sub's DSP will add a delay relative to the LFR's woofers. How do I compensate for that?

In a receiver with full subwoofer management, complete alignment can be achieved via the distance setting on the receiver and phase and polarity settings on the sub. My receiver is 2.0 with pre-outs so the only subwoofer management I have is the DSP crossover, and the sub's gain, phase and polarity controls.

I imagine the subwoofer output goes through the DSP as well rather than being hard-wired... in fact I think it has to since it needs to combine inputs from the L and R channels.

There could still be different path lengths as a consequence of not going through any filter logic, but it's also possible the subwoofer signal goes through a delay of approximately the same length as the filter stages. Don't know.

Hold on, I answered the opposite question from the one you were asking... and it's too late to delete the post... and I have to go out and try to get ready for the next big dump of snow... today looks to be the last snow-free day of the year... and I obviously haven't had anywhere near enough coffee yet.

So ignore this post other than as a potential source of amusement.

And no, I haven't had time to set up the LFR1100's yet, but at least they are finally in the right part of the house with the strapping taken off the boxes.

John, you're hilarious. Lol!

Mojo ... Start by setting it up as listed above. Then spend a few weeks with trial and error.

You may never need the subs. Personally, I look for material with bass below 20 Hz.

You don't. This means you are sane.

Actually, I don't look for anything in particular other than music I like. If it has content below 20Hz, I want to hear it.

I don't mind experimenting and trial and error but I do like to start as close to the finish line as possible with some science.

So here's what I've fingered out:

1. My LFRs are 10.7' away. My subs are 10.25' away. I can't get them any closer because of heat vents.

2. In time, the LFRs are 9.5 msec away. The subs are 9.1 msec away. So this means the sound from the subs will arrive at my ears 0.4 msec earlier than the LFRs.

3. At 40 Hz, 0.4 msec is 5.8 degrees. This is because a full cycle of 360 degrees is 25 msec at 40Hz so 0.4*360/25 = 5.8.

4. So I should be able to slightly advance the sub's phase control by 5.8 degrees and have complete alignment.

So far so good. The million dollar question in all this is,"What delay do the LFR and sub DSPs add"? That's a question for Axiom.

Note then that if any delay beyond 0.4 msec is added by the DSPs, the only way, for my set-up, to align the sub and LFR would be by setting the sub's switch to invert and then advancing the phase control. This off-set will still miss the portion of the waveform equal to the delay through the DSPs.

It appears that it's impossible to achieve complete alignment in time and phase without a distance control if the subs are closer to the MLP than the LFRs by the transit delay of the DSP.

Craig, on that second track from Steely Dan (What a shame about me), I have to turn the 800 or the 500s up a lot from reference to feel the infrasonics. Is that also the case on your end?

Mojo - no. I am running the system with subs and mains calibrated to 75 dB.

The only two variables left are sources and rooms. Both are cursed. LOL!

Oh...and me!And I've been cursed at a lot.