Frequency emphasis? - Axiom Message Boards

Axiom Home Page

So i have my theatre all setup downstairs now with an M3 mounted above and below the screen.

As I was watching some dvd movies and stuff I noticed that the dialog has a large emphasis sound at certain frequency's in the vocal range. It was getting quite annoying to me. When sitting off axis about 3 feet it was not as noticable when sitting in the sweet spot.

Is this a result of using M3s instead of M2s? or is this simply a room response problem that wouldn't be fixed with the use of an M2? I can say that this problem did not arrise when I had my speakers really far from the wall upstairs, none of the frequencies were really "pronouned", they were all even.

I think the proximity to the wall behind the speakers is having a big impact on the frequency response. And if that is the case, the M2s would be similar in performance would they not?

A part of me is wanting to exchange for the M2s (if Axiom would let me) just to see if that actually IS the problem.

Not really sure what to do about this, my wife would most certainly kill me if I told her that I wanted to exchange some of my speakers for some other ones.

I guess one of my other options would be to use the M3s upstairs, mount the M22s horizontally below and above the screen (sorry JohnK), and buy some M60s for the mains...that would avoid the whole "exchange" problem

.

Any advise would be appreciated greatly, this vocal thing is driving my nutso.

Could the problem arise from the difference in distance from the sweet spot to the top speaker and the distance from the sweet spot to the bottom speaker?

I remember reading your posts before, but why don't you just go with a VP100/V150? I mean, rather than trying to use Axiom bookshelves as centers and being disapointed in their sound, why not just go with a true Axiom center? It sounds like I'm being a smart***, but I really don't mean it that way at all. I'm just curious of your reasons *not* to go with a center-specific speaker.

As if I have room to talk: I'm using M22's as rear surrounds....

To your question, I suspect that an email to Axiom would yield the best results. Perhaps Alan will be along to explain why you're getting exaggerated frequency responses with the M3's. Alan knows all.

why?

specifically because I wanted to mount a speaker above and below the screen with a low end reciever. And I like them bookshelves as a centre channel, for some reason, this problem just arose when I moved my stuff downstairs.

I have also heard mixed opinions regarding the axiom centre channel which is why I went with bookshelves.

My only other option would be 2 VP100s wired in parallel which would give me the 4ohm impedance my 2 M3s are giving. And I didn't want the VP100 (2 VP150s would be 3ohm and something my yammy def couldn't handle).

I do not think it has anything to do with the fact I am using bookshelves as a centre channel, none whatsoever, smarta**

Those are fair enough reasons. Heck, you don't need a reason other than, 'cuz I want to!'. Again, just curious.

Going with the bookshelves also leaves you with a nice pair to do *something* with in the future if you ever upgrade, as opposed to a center that can really only ever be a center.

If you are using a second receiver to power the centers, you could buy a mono-signal splitter to wire between your pre-amp and the second receiver/amp. Split the center signal into two channels (L/R, perhaps) for the 'powering' amp. That would eliminate the problem of dipping the impedance too low with the parallel runs if you were going to try 6 or 4 ohm speakers. You could even adjust top-to-bottom balance by adjusting L/R balance.

I can say that I really like my VP150, and have nothing but positives to say about it.

Good luck!

Hutzal,

High or low end of the frequency?

Also I had to adjust the distances of my M3s. One is 10 and the other about 10.5 away from main listening position.

I'm also curious what frequency range you're hearing as being emphasized. It might be "boundary effect" if you're close to the back wall....

How would you be able to tell the frequency?

Its in the lower range for sure mabey from 100-150, It may be around where the frequency hump in the M3 occurs...

I am going to run some more experiments before I do anything. I'll try the top M3 by itself, then the lower M3 by itself.

THe top M3 is mounted about 5 inches from the ceiling, so its in a corner, it may be enducing the frequency hump I am describing.

I also may try an M22 mounted up there too, to see if it has the same effect...

Quote:

How would you be able to tell the frequency?

Is it the men's voices or the women/children's?

Soprano - Alto - Tenor - Bass. Which irritates you?

By default most men in their later years tune out soprano and alto.

If any of you watch Battle Star Gallactica, President Rosilin's (female) voice was doing it quite a bit.

I noticed it more a quiet talking, than louder talking.

Her voice is fairly low for a woman's voice, as I recall. You don't happen to have equalization turned on, do you? I don't remember if your receiver has it. I doubt that's what it is, but hey...

[Edited] I would think the M3 bass peak is at too low a frequency to affect most vocals. It's around the 100-150 Hz range and not all that big.

If you only notice this with the deepest male vocals then M3 response is a possibility. If it's in the upper vocal frequencies then boundary effects or even comb filtering between the two M3s seem more likely.

First thing to try is to disconnect one of the M3s (you might need to adjust the center channel level) -- if that makes a difference, then comb filtering is your culprit. Since your M3s are vertically separated it would actually be vertical angle that affects the response, but I find it's pretty hard to move a few feet off axis without moving vertically a bit at the same time.

Just don't move around to get a handle on comb filtering effects with anyone in the room or you'll end up getting rude comments about the big solo dance scene in Napoleon Dynamite.

I forget what receiver you have, but cranking the crossover frequency way up (many go to 200 Hz) is an easy way to eliminate the bass peak as a culprit. You'll get a bass hole instead (the sub probably rolls off around 100) but different is good, right ?

Are the M3s definitely "in front of" the TV, not behind the TV or a shelf even 1/2 inch ?

I'm guessing this is what you call v2 of the home theater -- downstairs, but still TV not projector ?

I am using a projector, so the speakers are mounted against the speaker wall, above and below the speaker.

I'll take pics tonite and hopefully be able to show you all what I am dealing with.

Was BG on dvd or TV?

I some times have real problems with broadcast.

Robb, although I'd be inclined to go with the M2s, if whatever the "emphasis" is(you're having trouble targeting it and you're right there; it's even tougher for us)has to do with positioning rather than the M3 "hump", then the M2s wouldn't solve the problem. Since the top speaker is diagonally a foot or so farther from your ears when you're sitting, check if the sound is different when you stand and the distances to the two M3s would be about equal.

My guess is comb filtering as well with the likelihood of phase cancellations and reinforcement at certain frequencies. Its the reason I have always shyed away from dual speakers in the centre channel. I agree substituting a centre for the duals would likely solve the problem.

if you disconnect one of the pair of centers,
does the anomaly lessen, or disappear completely.
try it first with the lower disconnected, then the upper.

this may help you decide if it is an issue of room characteristics , or a issue of phase cancellation.

i just got a regular vp100, maybe one day a vp150.

hth
randy

I watched the Matrix Revolutions last night, the vocals all seemed to be fine, there was no emphasis on any frequency.

Perhaps it could have been the source? BSG on DVD? I'll conduct more experinments, but I am suspecting that the source is the issue.

Hi Hutzal,

If what you were hearing was a combination of boundary effects plus the little M3 bass hump, you'd hear it on all the male voices (or female alto voices) regardless of the source.

Miking does vary quite a bit from one movie to the next, and sometimes microphones that have uneven response (bass output is boosted when the microphone is placed close to the actor) are used for whispered or "sotto voce" dialog. In the latter case, the upper bass coloration is very noticeable and annoying.

But if you didn't hear it from the Matrix Revolutions movie, then it's not the fault of the M3's location or boundary effects from the wall.

Last night, with friends and colleagues, I watched part of a truly terrible movie calle "One Night With the King" (avoid it!) with highly uneven microphone technique that varied from one scene to the next and made for lousy dialog intelligibility.

Regards,

Thanks Alan, after watching The Matrix, this is what I came to realize, that it was probably the source not the speakers. So strange that upstairs I watched alot of Battlestar Gallactica and never really experienced this problem. I will continue to intently listen, I'll report back with updates if I have any.

Thanks for chiming in, I was seriously considering switching up for M2s (which I didn't really want to do).

-Robb.

Robb,

IMHO you have the right speakers for the job.

Switch back and forth between center and phantom center. They should blend very well.