Axiom Home Page Forums General Discussion Home Theater M60s playing LFE channel

I've been playing around with various settings on my receiver, particularly experimenting with different options for subwoofer calibration. Out of curiousity, I set my M60 speakers to large, all other speakers to small and set the subwoofer to off. I'm using an Outlaw 990 receiver (and 7125 amp) and the net effect of these settings is to send the full range signal to the M60s, along with the bass from the center/surrounds and the LFE channel in DD/DTS recordings. To test it out I played a couple of bass intensive scenes - Finding Nemo (Darla taps tank) and Star Wars: Attack of the Clones (opening scene where ship explodes).

WOW - I was not ready for the results. For some reason, the LFE effects are significantly magnified through the M60. The output levels are extremely high. I took some measurements using a SPL meter. Playing these scenes with the LFE routed to the M60 (and no sub) hit peaks of 105-110 dB when playing -20 dB from reference levels whereas they hit peaks of 90-95 dB when the LFE is routed to the subwoofer. I did not expect this.

Is this normal? I did not expect the LFE channel to play so loudly through the M60. I don't plan on keeping the system configured this way but I thought it interesting nonetheless. It does confirm that the M60s can play reasonably low at fairly high SPL levels. But I'm surprised the Outlaw 990 sends such a strong LFE signal to the front mains when configured as such.

Any thoughts?

It may be that the volume knob on the subwoofer is not turned up all the way so no matter how strong a signal the receiver is sending it volume level set on it’s internal amp is limiting the spl. I’m assuming here that it’s a powered subwoofer.

It may also be that the M60s are “corner loaded” and receiving a bass boost from room reinforcement.

Just a couple possibilities,

Dean

P.S. Still it’s a nice demonstration how powerful Axiom speakers are.

Should I cancel my sub?

Yes.

in fact cancel your entire order, AV123 is calling your name.

Oh, snap!

HMMmmmm No smiley face. HMMmmmm

I can see the gears turning in your mind as if it were a steampunk computer.

I've always wanted to say "Steampunk".

Sound like a beer.

I've been thinking a bit on this one after my original post. One reason might be that the LFE channel on my receiver (Outlaw 990) runs at a fairly high level compared to the other 5 channels. The receiver's front channels are trimmed by -3 dB whereas the subwoofer's channel is trimmed to -10 dB to level match the speakers to 75 dB. Additionally, the EP500 amp's volume control isn't fully amplifying the LFE signal (the volume control is only at 7:00) whereas my Outlaw amp is fully amplifying the front channels. Therefore, when sending the LFE signal to the subwoofer, it is being attenuated by -10 dB at the receiver and further reduced by the subwoofer's amplifier. Whereas sending the LFE signal to the front mains, the signal is being attenuated -3 dB at the receiver and fully amplified by the Outlaw amp. This might help to explain why the LFE signal is much stronger through the front mains than through the subwoofer.

Does this make sense? I'm not an expert and this is my simple, layman's reasoning. I also agree with the post above that the positioning of my mains relative to my subwoofer might be causing some room reinforcement of the bass.

Is it normal that the LFE signal is much stronger than the other channels?

Thanks!

Doesn't make much sense, no. The receiver is acting as the amp for all channels but the sub. The sub has its own amp, which the receiver doesn't control; that's the volume knob on the amp.

It's not uncommon at all for different channels to have different level settings--especially the subwoofer.

Makes sense to me.

FWIW, I have a separate pre-pro receiver (Outlaw 990) and amplifer (Outlaw 7125).

Why then, would the LFE signal play so much louder on my front mains than my subwoofer, when both channels (front mains and subwoofer) have been level-matched?

Keep in mind, I'm not talking about the frequency response. I'm pretty sure the subwoofer is still playing the lower frequencies whereas my M60s aren't - but the SPL level of the LFE signal through the M60s is almost 10-15 dB higher than through the subwoofer. How is this possible when the speakers have been level matched through calibration with an SPL meter and the receiver's test tones?

fredk - I didn't see your post before posting my reply. You seem to agree with my analysis - correct? It does seem to make sense to me - but I'm no expert in these matters

ICE, With my old 500 and original 600 amp that I got replaced, I had the same situation with my Denon. The sub was on about 6-7 o'clock, and the levels on the receiver had to be around -10 to achieve the same levels as my m80's. Some of it has to do with placement in the room. Moving the sub from the various corners, or trying the side wall changed this somewhat. A smaller room may be different.

Currently I have my 600 in the back corner, and at 6 o'clock, the receiver is at -2dB. The mains are around +1dB. As long as they all read the same on the SPL meter, that is what is important. Also, try calibrating to something like 78dB's, 75 is hard to read on the meter as it falls at the high end of the 70dB scale, and the low end of the 80dB scale, using the analog meter.

I think the Axiom sub amps need a flat/-20dB in/out button ahead of the rotary level knob. Whats the point of having a knob that rotates 270° when the first 30° gives anyone all the gain they could need?

It's like the el-cheapo HTIBs that have volume controls that give you full output with a 20° turn so it feels powerful, but offers no range to the control. No one wants a knob that you have to rotate far to get volume, even if the end volume is the same anyway!

Hey Mark

I remember some NAD integrated amplifiers used to have this feature. I think that would be great addition to the Axiom subs.

paul