Axiom Home Page Forums General Discussion Advice from Axiom Owners Help - M60 & VTF-2 bass rollercoaster

sorry, what about two channel? will it sound tinny, or is that what the sub is for?
humbly,
dan

Dan, as far as the sub crossover control goes, if you set all speakers "small" and the low frequencies are assigned to SBWF, not both, the sub crossover is unnecessary. Since the EP350 is one of the subs that doesn't have a switch or input that bypasses its crossover, the next best thing is to set it all the way up around 150hz, where it's out of the way of the 90hz crossover the 1300 does.

The sub level control doesn't necessarily have any good starting point. The idea is to set a proper sub level, either by ear or by meter. Both the control on the sub itself and the provision on the 1300 for changing sub level effect this. Some like to start with the sub control low and the receiver sub level around the middle. Then the sub control would be raised until the level on the meter or by ear is about right. Most subs are set too loud; they shouldn't be so loud that they draw attention to themselves. The idea is to give the impression that the sub is silent, but the other speakers are putting out more bass.

On two-channel, I don't quite follow, but the sub handles the low bass for that, just as it does in 5.1 play.

john, thanks. thought in the past, while watching tv, in 6 channel stereo, which my wife likes, something was lacking. as fot the a and b speakers, that was solved when someone, perhaps you pointed out that i was using the incorrect output on the receiver.
dan

Let me ask a question about the crossover settings for the receiver. When I have the main speakers set to SMALL and their crossover at 80Hz. I'm expecting nothing to be sent to the mains much below 80Hz. I understand there is a gradual rolloff. Is this the correct assumption?

When I ran the LF/sub and RF/sub low frequency sweeps on AVIA with the described setting I was noticing a serious amount of air flow coming from the ports of the M60s in the 40 - 60Hz range. Does this means the internal crossover in the receiver is not working propery?

Toby, my previous reply still stands, but I'll add more comments. "Gradual rolloff" is a correct assumption, "nothing" isn't. The 525 crossover(or filter)rolls off the response below the selected frequency at about 12db per octave. So, set at 80hz, 40hz should be about 12db down, which is a lot, but not to zero.So,it depends how "serious" the air flow at 40hz is. Try temporarily setting the cross on the 525 to 40hz; the air flow should be significantly stronger at 40hz if it's working.

So far as the heavy bass between 60 and 80hz, since you don't have the sub in the corner where it would excite all modes equally, it may be exciting the 70hz floor to ceiling mode(560hz/8')more prominantly. If you want to tinker with this, besides putting the sub into the corner, you can try 80hz and small on the 525, but put the VTF-2 crossover on and try to create a partial hole between 60 and 80hz by setting it at 60hz(if the marking is accurate, which it may not be).

John,

Thanks for the clarification on the crossover. I had no idea of the rate or magnitude of the roll-off.

Actually the sub is in the rear left corner of the room where Dr Hsu had recommended. I'll try your suggestion about creating a hole. Thank you.

Yes, judging from the published impedance curve of the M80, its ports are tuned at around 40-45Hz. So, M60's ports are likely tuned right at around 50Hz. I would expect lots of air velocity to/from the ports when driven near the resonance frequency, even if it is attenuated 8-10dB by the high-pass crossover on the receiver.

If you are still in doubt, just set the M60's as LARGE and see if the air flow further increases.