Axiom Home Page Forums General Discussion Advice from Axiom Owners Low frequencies overloading the M2ti possible?

Hi,

I currently have two M2ti used as front speakers (on bookshelves) in a 6.1 system (including an Outlaw 1050 receiver and a Hsu sub). I really like the clarity and wide soundstage of the Axiom speakers. After tweaking by adding an elliptical neoprene ring around the tweeter, there was even more clarity and the sound stage became deeper (because reflection off the side walls were reduced.). Now, here is the dilema.

Configuring all speakers SMALL and setting my Hsu VTF-3 sub to ON (Xover set at 60Hz), as popularly advised, gave a pretty good performance. However, there seems to be a slight frequency gap in the cross-over region and the sub could sometimes be located. Increasing the Xover to 80Hz did not work well because of irritating sub localization problem (the sub made known it was behind the sofa - the only place where there is room for a sub)

Recently, I changed the configuration as follows:

Front (M2ti) set to LARGE, all other speakers set to SMALL.
Receiver Sub setting: OFF (to direct the LFE to the front speeakers.)
Sub low level inputs were connected to the front right and left preamp-outs, and internal sub cross-over adjusted to approx 60-70Hz.

This configuration provided an audible improvement in soundstaging and speaker/sub integration. The sub localization was also improved (sub was less likely to call attention to itself). I have been happy about the new sound.

What is the problem then? Well, I am afraid that all that low low frequencies at high level may distort the sound or even damage the M2ti small drivers (particularly during the bass-heavy, explosive action movies).

So I recently placed an order for two 400uF capacitors, planning to connect each in series with a M2ti in order to reduce the power level of frequencies below 40Hz reaching the M2ti.

I am not sure how the capacitor would affect signal phase (soundstage) and the frequency response curve above 70Hz.

My question: is it advisable or neccessary to add the capacitors?
Any other comments on my planned set-up?
Thanks.

You can run your M2s in the large mode but the small woofer/cabinet combination will be limited in it’s low frequency output anyway so I am not sure this is a solution. It would seem like the real solution is a steeper x-over on the sub-woofer. Because of the limited low frequency output of the M2s running the receiver on small makes a lot of sense (the speaker is not doing a lot below that anyway). Setting the sub x-over to 80 Hz should not produce any directional frequencies and hence should not be position sensitive. An electronic x-over in the line to the sub seems like the ultimate answer for your system. Other than this, M3s or M22s up front would give you a bit more low frequency information and allow you to run the system on large and lower the x-over frequency setting on your sub.

Imind, since your 1050 also has a variable crossover, in addition to the sub crossover, it wasn't entirely clear to me which one, or both, that you were referring to when you mentioned various crossover frequencies which you tried. I'll give you my opinion. You paid good money for an excellent sub and you should use it in the frequencies where it gives better performance than the M2s. This means up to around 90hz. Yes, it can be localized at this frequency if it remains right next to you behind the couch. Despite what you've said, find some space near the M2s, even if you have to go to the extreme of using the VTF-3 as a stand for one of the M2s(not really recommended).

Next, on the crossovers. I'm not sure where it's been "popularly advised", but if you set speakers "small" the sub crossover on your VTF-3 shouldn't be set at 60hz or anything else. The VTF-3 has a bypass which completely removes its crossover from the picture and this is the setting to use at "small" so that the cross in the 1050 takes care of all the bass management. It's incorrect to think that somehow the sub crossover can improve the "blending" or "integration" which has already been accomplished by the receiver cross. It can only cause harm, that's why the bypass is there.

Considering the bass capabilities of the M2s, the 1050 crossover or filter should be set at 80hz, speakers "small" and sub cross bypassed.

Hello imind,

I agree entirely with JohnK's advice. I suspect what you may be "localizing" is the acoustical/mechanical vibration of the Hsu subwoofer behind your couch. If you use 80 Hz on the OUtlaw's LFE setup menu, there normally should be no localization of frequencies to the subwoofer, unless the low-pass filter in the Outlaw doesn't have a steep enough slope. I doubt that's the problem. One other possibility is you might be running the sub too loud, a common-enough condition among many enthusiasts who feel that if they can't "hear" the sub, then it's not loud enough. ..

But you should definitely be bypassing the Hsu's internal crossover.

Regards,

My 400 uF capacitors arrived last Friday, but I am not going to need them ... thanks to Ian's, John's, and Alan's advices and precise analyses.

If you can spare me a few minutes of your time, I will describe what happened so that Axiom owners in similar situations may possibly benefit from the experiences.

I reset all speakers to SMALL and the sub to ON. Reconnected the sub to the receiver's sub-output. Sub internal crossover by-passed.

I found that a receiver crossover frequency of 80Hz gave a fuller (better) sound than a 60 Hz Xover, apparently because the VTF-3 sub was allowed to handle a more extended frequency range where it was the better performer, as John predicted.

I was happy with the sound, but the occasional localization of the sub behind my sofa led me to tweak further.

I could not relocate my sub as my front wall is lined with buit-in cabinets below and bookshelves above. There is sinply no room up front or on the sides for something as substantial as the Hsu VTF-3, unless I undertook a major room overhaul (which I might still do in the future).

The sub sitting right (or left) behind my back is the situation I have to live with for now.

Worse, as Alan suspected, I tend to set my sub a few db's higher than it should be -- to satisfy my bass-loving taste and to compensate for the low volume level listening environment that I am sometimes subject to.

I flipped the sub crossover by-pass switch IN and OUT several dozen times, leaving the sub internal crossover set at 85-90Hz.

I found that engaging the sub internal crossover (set at 85-90Hz) did not degrade the overall sound noticeably while reduced -- but did not eliminated -- the sub localization problem (as expected). I wish I could implement John's decisive solution to relocate the sub up front at all cost.

I was surprised that the cascading of crossovers (24db/octave for the Outlaw and 24 db/octave for the Hsu) apparently did not do substantial damage to the sound. But then I am far from having audiophile ears, nor true audiophile equipment.

I don't know about other folks, but I find these discussions very enlightening for me. This is a great community of like minds where more knowleadgeable members such as Ian, John, and Alan took the time to participate and help out.

Axiom have done more than simply produce great sounding speakers!
Thank you all.

imind

That's great you have found some working methods to help out your speaker performance.

JohnK's advice on moving the sub up front is well founded.

When i first received my EP350, i had virtually no room at the front of my listening area for this speaker. It originally sat next to my couch to the left side. Unlike your setup, i had anticipated too much bass in having the sub so close to my listening position so i turned down the volume but the sound was still very mixed and not intergrating very well with the rest of the setup. Trying different cross over settings only made things worse.
So, i pushed and pulled and wedged the EP350 in right next to my front left M60 tower.
Without doing anything to the crossover, phase or volume knobs, i experienced a MASSIVE increase in the sound integrity. It really did sound good, a world better than sitting next to the couch. This wasn't really unexpected but more a mild disappointment since the best place for the EP350 (for function and aesthetics) would have been next to the couch.
Of course it is easy to walk through the proper steps to setting up subwoofers at home. Get down on your hands and knees, move the sub around the room until you hear the best sound, etc. However, due to the diverse nature of each listening room, the possibility highly exists that the best sub location will be in an area simply impossible to place permanently.

The moral of the story, sometimes you simply have to get out the crowbar to make it work!
(i think a tv repair man once told me that, oh, no, waitaminute...it was Randyman, now i remember)

Imind, glad to hear of your improving results. Incidentally, your VTF-3, M2s and 1050 are certainly"true audiophile equipment" in my opinion. Remaining placement thoughts : pull the M2s out a few inches over the front edge of the shelves ; would it be acceptable to position the VTF-3 sideways right up against a cabinet with its 15 inch width protruding beyond the cabinet and the driver positioned toward the middle of the room, more or less under one of the M2s.

You folks are truly fanatical perfectionists, I come to believe.
And to a lesser degree, so am I.

Still you realize there are times you do not have it your way. Then if you remain undisturbed, you may have partly discovered the secret meaning of true happiness.

Moving the sub up front is one of those times. John’s and chesseroo’s ideas contained great truth though, and I will try to implement them in a future project which would involve dismantling the built-in cabinets and building new ones. I did not, however, have any problem pulling the M2 almost half way out of the bookshelves. Depth and imaging was great.

My rambling probably gave you the impression that things were much worse than they actually were. In fact, by moving the sub less than two inches this afternoon, I accidentally hit a perfect spot where not only was the bass tight, its quality and quantity at all three seating positions on the sofa suddenly became uniform. Sub localization was noticeable only during rare music passages.

I profess to have compromised unforgivably by using both the receiver’s and the sub’s crossovers for the sake of minimizing sub localization. Since my system in-room frequency response had a bump in the 95-150Hz region, a steeper sub frequency rolloff above 90 Hz would hopefully have a lesser detrimental effect on the smoothness of the overall frequency response than if it were flat to begin with. I have absolutely no idea about the possible effects on distortion and phase shift.
Best regards.
imind