Axiom EP500 volume trim and SPL meter.

[darthkringle]

I have spent much time in the setup of my new axioms (M60, VP150, QS8, EP500), and have finally found what appears to be the best spot for placement (relative to my options). Now my problems:

I can find sub/tower blending/5.1 nirvana at specific overall volumes only. What I mean is that, if I turn the master volume on the Yamaha RXV2400 up or down from a certain point it affect the bass smoothness/response. What seems weirdest is If my master volume is at -18 on the Yamaha w/the EP500 db trim at -10, it sounds AMAZING. If I simply turn up the overall volume to -15 to get more overall volume, I appear to actually LOSE BASS???? What is happening here?? It's like the volume from other channels is cancelling out some of the EP500.

Second question- Can I remedy w/my SPL meter and DVE test tones? I used it to get to this point, but what I don't know is what MASTER VOLUME setting should I use to start? I used 0 on all channels and 0 on the master volume as a starting point and calibrated all channels to 75db from there. Is that why I'm messed up? Should I have set the volumes differently during the test?

VERY happy w/my axioms, but really want to find the right channel volume settings here regardless of overall volume.

Thanks as always for you all's help.

 

[MDS]

You did the calibration correctly. The sub is problematic to get right in any event and the Radio Shack SPL meter reads too high for low bass.

SV Subwoofers has a compensation chart if you really want to dial it in exactly: http://www.svsubwoofers.com/faq_rscomp.htm

I think the real problem though is setting the subwoofer itself to -10. Try setting it to zero and rely only on the receiver's subwoofer level trim.

 

[darthkringle]

Actually, what I meant was the sub trim on the receiver is at -10. The strangest thing is that w/the sub(on the receiver) at -10 and the overall receiver volume for all channels at -20, it SOUNDS AMAZING. When I bump the overall receiver volume up though, I seem to lose bass........very confused.

 

[MDS]

Ok...my mistake.

I still don't like the sub level on the receiver set so low. I suspect that the volume dial on the sub is pretty high if you had to turn down the receiver level so much to get a 75dB reading on the meter. Mine is at zero with the sub volume about half-way. It's probably about 2-3dB too hot due to the inaccuracy of the meter at low frequencies but it seems to blend well so I leave it.

The receiver sends a line-level signal to the sub and the sub amp probably needs a certain voltage to produce its maximum power, just like amps often say something like '2V rms for rated power'. At low volumes it probably sounds fine because our ears are not so sensitive to low frequencies and it takes a large jump in power to be able to distinguish a loudness difference between bass frequencies. But when you turn it up, the sub isn't getting a hot enough signal to amplify and just can't produce the higher SPL required for you to actually perceive the increase in loudness. It's also possible that the problem is entirely due to room modes and you have a giant suck-out at some frequency that is more noticeable when the volume is turned up.

I've never seen nor heard of this problem before and my theory could be all wrong, but one thing is for sure. The sub's auto-on feature won't work too reliably with its input signal attenuated by 10dB. Try to do the calibration again with the receiver sub level at or near zero and only vary the sub's volume control. I would be curious to know how that changes things, if at all.