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

Again...I personally felt that setting the crossover at 80hz with the M60's was too high. 40-60 was best for me. MAYBE 80hz for a movie, but for music, I'd keep it lower.

i have my 60's set to large, lfe to sub + mains on my yammi rxv1300. i have the volume on sub about 8 o'clock, and the x-over all the way clockwise. sounds good to me. is there a better way, or just preference?
dan

twodan,
I'm surprised that you haven't complained about 'muddy' sounding bass with your setup.
The idea about using one crossover is to blend the sound frequencies played by each driver. Since the crossovers form a declining curve, you would typically set the crossovers at the points where drivers 'interfere' with each other's sound frequencies the least and yet create as flat a frequency line as possible once the curves do collide. This is to eliminate any holes in the frequencies played back as well as eliminate or reduce the amount of material played by more than one driver.

In your case, by turning the M60s to large, they are allowed to play their full range of frequencies which according to the Axiom specs goes as low as 37Hz (+/-). By turning UP the crossover on your subwoofer, you are allowing it to play these low end frequencies right up to about the 120Hz mark overlapping the same notes the M60s are playing. Usually this makes the bass sound muddy, heavy or overbearing and not particularly defined.

Here's a suggestion to test, keep your receiver settings the same and try turning the sub crossover down to about the 80Hz mark. Compare this to the max value you are using now. Then turn the sub crossover down to 70Hz, then 60Hz then 50Hz mark and so on and listen to some music each time. Get an idea for how the effect sounds.
Pick the sub crossover setting that sounds good to you.

I have found with my room, system, that the ep350 crossover of around 50-55Hz works great with the M60s. According to the NRC graphs for the M80s (about as similar a comparison as possible), this appears to be the range in which the lower end of the speaker starts to dropoff so it all makes sense. You want the subwoofer to pick up the low end sound from the M60s as they begin to trail off due to their driver limitations.

The other method described for setting up a system is to set your speakers to 'small' in your receiver. This sets up the receiver's built in crossover (typically around 80Hz) for your speakers. Since the M60s and the subwoofer are now 'controlled' at the 80Hz mark it is often recommended you now turn up the crossover dial on your subwoofer to 'get it out of the way' of the receivers duties. Some subwoofers, as i have recently learned, have a switch to actually circumvent the subs' internal crossover completely.

Toby,

Those are room modes -- plus/minus 10dB swings are nothing rare, and unfortunately you have them. What are the approximate peak and valley frequencies, as judged with AVIA's low-frequency sweeps? Anyway, in order to simplify the trouble-shooting, I would do the following:

1) Set all speakers as SMALL; bypass the crossover on the VTF-2.
2) Set the subwoofer crossover on the receiver at 80Hz.
3) Try several feasible locations for the sub, testing it with the AVIA sweeps after basic calibration.
4) In each location, try both "max extension" and "max output" modes on the VTF-2 (one vs. two ports open) -- the sub has to be recalibrated after changing the setting.
5) In each location, try both positions of the sub's phase switch.
6) In each location, try several different sub crossover frequencies on the receiver.

I also second the suggestion that you FAX a diagram/measurements of your room to Dr. Hsu (see their web site).

Good luck!

i didn't think i could adjust the yammi rxv1300,; thought it was fixed around 90. am i wrong?
dan

First off, thanks again to one and all for the suggestions.

I spent some more time last night experimenting with various settings - M60s set to SMALL with several crossovers, M60s LARGE with sub set to varying crossovers and just LFE. With my HK 525 I can set the mains to SMALL and specify individual crossovers for mains and sub. With the mains set to LARGE I can set the sub to be SUB, SUB (LFE), or SUB + L/R, the latter having a synchronized crossover with the mains.

I am wondering if the crossover on my receiver is working correctly. With the M60s set to small and both the speakers and sub crossed at 80Hz (these can be set independently), a low freqency sweep produces a significant amount of air flow from the ports of the M60s below 40Hz. Could this be the M60 drivers responding to the air moved by the sub output?

Taking the advice from an earlier post I took a different approach to lowering the crossover - M60s set to LARGE and the sub set to 'SUB + L/R' with a 60Hz crossover - Holy S***! - serious difference in sound (very different with than having the M60s set to small with the same crossover)- much more transparent blend, much less localiztion, and MUCH more low end support. It was pretty late and at that point I just wanted to relish the new sound. I need to get AVIA back out and check the output.

Sushi,

I had submitted a diagram of my room to Dr Hsu prior to buying it and it's currently in the location he'd suggested. I've tried Alan's crawling method and tried a couple other locations and found this location produced the best output, but it could also be exaggerating the room nodes.

The nodes seem to differ between LF and RF, with a LF+SUB sweep, the big node come about between 70Hz and 80Hz, which lead me to believe it was a crossover problem. But with a RF+SUB sweep, the big node was up in the 90Hz to 100Hz. Then with both I seem to have a pretty significant (+10dB)dip between 40Hz and 50Hz.

I'll try moving the sub and further experiment with the output mode and phase options now that I've found a better speaker/sub configuration and see if that tames the nodes.

Thanks!

Dan,
There are 2 crossovers at work here, one is located on your Ep350 and the other is on your receiver.
When the main speakers are set to large, the receivers crossover is shut off.
When the main speakers are set to small, your Yamaha may have a fixed crossover, usually around 80Hz. My Onkyo 797 uses 80Hz but others can vary and higher priced models sometimes allow for a selection of 3 or 4 frequencies.

My suggestion was to set your main speakers to large (which is how i believe you already have them set), then play some music and change the crossover dial on your EP350 from higher to lower. This should give you a better idea as to how this dial changes the sound integration between your sub and your M60s.

Toby,

Your description of what happened when you set the M60s to "large" (with the sub supplementing below 60Hz) does make sense. It seems that, by driving the room from three separate locations (FR, FL, and Sub), you are canceling out the big room-mode dip at 40-50Hz to some degrees. So, maybe this is a good starting point for you for further tweaks.

The different peak frequencies you observed between the FL+Sub and FR+Sub sweeps are nothing surprising. Are these peaks seen with the M60s set to "large" and the sub added below 60Hz? Anyway, this strongly suggests that it is worth playing around further with the placement of the M60s as well, since your major room-mode peaks are above the sub frequencies.

Dan, this was also discussed about a month ago in connection with your "B" speakers hookup problem. As chess pointed out, you're still not getting proper bass management. You've made three settings which can be good, but not with each other. If you turn the sub crossover all the way up, and then you've also set the M60s "large" and the low frequencies "both" that means that both the sub and the mains are playing the bass all the way up from the bottom to about 150hz. Again, as I previously suggested, set the M60s "small" which sends the bass below the 90hz fixed 1300 cross to the sub. The low frequencies should not be "both" but just SBWF. Then, the sub crossover is correctly set all the way up to get it out of the way.

john, thanks, i'll set them to small, but where do you suggest i start with settings on the ep350?
dan