Axiom Home Page Forums General Discussion Stereo So NOW I'm a real Axiom owner...

The 8033 user's manual doesn't go into very great detail about how it works. From what I've read online, it attenuates the peak frequency (one or more?) without doing any valley boosting. Therefore, the overall effect is to reduce the signal strength (across the sub's spectrum). To compensate, you may have to slightly increase the sub's volume to balance the "corrected" sub with the main speakers.

You have the choice of equalizing a specific "sweet spot" (what I did) or running multiple calibrations across a wider area & letting the box average them.

Alas, I have no spectrum analyzer other than my iPhone, which is notoriously uneven in the deep bass. There should be a plethora of good information (and professional reviews) of the 8033 around on the internet. Feel free to investigate. My comments are but my own (very initial) impressions.

I must agree with you, though, this device does sound VERY cool!

I'll have to check it out. Thanks for the speedy reply! In theory, if you have a problem centered on 60hz room treatments and seating position is the only cure. This device has me curious what tricks they employ to acheive near flat response without losing too much sub headroom. They gotta be masking the fundamental standing frequency somehow. How they replace it has me baffled. The device does apparently introduce sub audio lag. Have you noticed this?

No lag that I can tell. I could easily adjust via the "phase" dial on the sub if needed, but the easiest way (for movies) is to add a foot of distance to the sub from the listener electronically. This would force my Oppo to delay the other channels by an equivalent time to keep the whole thing in phase.

As to "replacing" a peak, that's NOT what the 8033 does. It instead reduces the amplitude of the peak to match the mean (average) volume. Note that valleys are NOT boosted to the mean - this would require LOTS more power from the sub amp (possibly clipping the amp and damaging the sub). So any valleys in the response are left alone. Only peaks are attenuated.

You'd think that this would be only "half-effective," but the actual result is significant. I was contemplating an additional subwoofer to smooth my response (and may yet go that route), but the 8033 alone has improved the bass so much that I plan to live with this for awhile before spending another thin dime. The 8033 is that good.

I'd also say that my room is MUCH better than average for bass to start with. It's a large room with a "vent" in all four corners to other areas of the house (hallway, foyer, stairwell, and large opening to another room). Therefore, the room was "non-boomy" by design. Nevertheless, the 8033 made a huge difference for me. If it helped MY room that much, I'd think it would be even more effective for rooms with corner problems.

I'd also contend that you don't lose sub "headroom" by attenuating acoustic peaks. The sub placement and the room already add huge (but frequency-specific) efficiency at the peaks. Therefore, if the sub amp must play at 50 watts of output at 40 Hz, the equal-amplitude output at a 60 Hz peak may require only 5 watts. By amplitude-equalizing the peaks, the sub's amp actually works less hard to maintain a flat response. So if you want to think of it that way, you actually GAIN headroom by attenuating room peaks.

Cheers - Boom

I'm replying just to keep you talking now. Excellent information Boom.

When you say reducing peak frequency are you meaning bumps in the in room response? (like 20db spikes or so?). I know one method is to reduce the ouptut at those peaks to reduce the significance if the null vs the mean. But increasing the sub gain to compensate usually just reinforces the null.

My fascination is how the standing frequency, the one responsible for the massive null in most rooms, is handled. This is dimension and placement dependant. No matter how much power you apply to a standing frequency the null will never be filled. This is why I speculate it must be masked out and replaced by some blending of harmonics and perhaps time (phase) shifting.

At both AVS and Hometheatershack, they have tested and shown before and after graphs. Quite impressive. The fellow behind REW ran some tests and it seems like a very good sub "set it and forget it" device. When he's impressed, its the real deal.

Nope - the 8033 does NOT "mask" or "fill" any nulls in the frequency response. As you say, "No matter how much power you apply...the null will never be filled." You are exactly correct. The 8033, therefore, does not even attempt to fill any nulls.

However, "for every null, there is a peak." The 8033 DOES attenuate these peaks to the average SPL. The equalizer must be variable in both amplitude and frequency-range to do so. Some peaks will be broad & shallow - others narrow & steep. The 8033 adapts, apparently, to both, and thus, must be parametric in nature.

I agree with AVS & Hometheatershack in their evaluations. This is the most effective EQ I've ever heard for bass. The "set it and forget it" nature is also appealing - especially since it's so accurate.

Fun, fun, fun!

I am with you Boomzilla the 8033 is a great little unit,I use one in my bedroom with a pair of 8" Yamaha subs and it does wonders. The bass is much tighter = less boomy. In my main room I have a XMC-1 from Emotiva with Dirac and use a Minidsp for phase alignment. Something I have found is that using dual subs that are not positioned correctly can have all kinds of phase issue, in the end I put one at the front right and one at the front left. May build a pair of 18's this summer.

And I ordered a second subwoofer yesterday. I plan to leave the first of the two in the front left corner, and to place the second against the front wall about four or five feet from the first. I'll then run the 8033 calibration again & see what I get.

I hope this wasn't a waste of money, but I do have 30 days to return the sub if I doesn't work out. With the second sub providing headroom, I plan to use the 25 Hz. EQ on the 8033 for a tad more extension.

I'll report on the results.

OK - The second sub is installed, calibrated, and working. Initial impressions = yawn.

Did I really spend $700 for THIS? Actually, I think that the single sub in the corner sounded better than the two of them along the equipment wall.

Potential issues: The subs may do better closer together OR the subs may do better in the same corner?

Here's what I've got at the moment:



Don't get me wrong - the pair of subs are better than a single sub in the corner (without DSP). But the single sub in the corner WITH DSP sounded every bit as good as the two subs currently do with DSP.

I think that my next move will be to put the pair of them in the corner.

If that doesn't work, then it's time to call the vendor & ask for their assistance, but I'm hoping that youse guys can pitch some good advice my way?

Thanks in advance - Boom

Boom, did you check the phasing between the 2 subs.
from 0 to 180 degrees, there could be a difference in total output of 6 dB or more.
if i remember right, this is done before syst. calibration, using a SPL meter at the MLP, (right between the 2 ears).

There is a pretty good chance there's a better spot in the room for them....
It might be awkward and it might not look that great but moving each sub to its sweet spot in the room will (regardless of the sub) satisfy your need. 2 good subs playing nice together should be felt more than heard. Your smile will hurt, then you know.