Axiom CC questions? (1 Viewer)

[Rick Radford]

I feel I should clarify my "weakest" comment regarding the Axiom VP100 I made in another thread.

I've not had any other CC with which to compare. My complaint is that occasionally, I think the CC is a bit on the nasal side.. but that could be because of the location (on top of a 32" TV inside an entertainment center) or maybe the source is just nasal (like Dick VanDyke). It's not that way all the time.. just occasionally.

I probably won't know for sure how to regard the VP100 until I've had some other CCs in for a test run. But first I'm gonna try one of my surrounds (M3Ti) as a CC and see if I can get some idea of the differences involved.

Otherwise, I'm completely satisfied with the M60/M3 series speakers.

 

[Brian Bunge]

Rick,

Are you going to stand up the surround speaker like your mains? This is the proper way to evaluate it as a center channel. No speaker, IMHO, should be lying on it's side. Not even a center channel.

Brian

 

[Rick Radford]

yes, Brian. I plan to run it upright for my test.
However, aesthetics sometimes are a larger (WAF) concern.

 

[Brian Bunge]

However, aesthetics sometimes are a larger (WAF) concern.

That's where I got lucky! I've got dual 12" sub enclosures (25"H x 15"W x 22"D) with ACI Emeralds on top of each and an Emerald standing upright on top of my Pioneer Elite 53" TV. The center channel is the only one with a grill. That's because I bought it complete but I built all the others. My wife never even mentioned it!

Up next is an 18" sub with a 2500W amp. When I told her about it she just shook her head but didn't shoot down the idea!

Let us all know what you think!

Brian

 

[Ron Reda]

I've not had any other CC with which to compare. My complaint is that occasionally, I think the CC is a bit on the nasal side.. but that could be because of the location (on top of a 32" TV inside an entertainment center) or maybe the source is just nasal (like Dick VanDyke). It's not that way all the time.. just occasionally.

The only CC I've had to compare the VP100 to is the JBL N-Center, which I feel is not a fair comparison. Granted, the JBL N-Center was used in a significantly different system at the time (a LOT more low-fi than what I'm running now) and I'm sure my ears have matured some since those days, but I think that the N-Center may have sounded a tad better. Specifically, the sound it threw was more "open" and robust sounding. Maybe it could be due to the fact that the JBL was a ported speaker and the VP100 is a sealed enclosure? I'm not sure. While perhaps Rick's CC positioning may not optimal, I hear the same sound characteristic emanating from my VP100 from time to time depending on the source. BTW, my VP100 is located on the edge of my entertainment center above my 32" TV.
Again, I'm not at all bashing the VP100...I like it a lot. In a room of small to moderate size, I think it would do a great job. However, I just feel that the VP150 would better serve my listening environment and HT tastes a bit better.
Regards,
Ron

 

[Jedd]

This question was posten on the axiomaudio forum:
horizontal MTM arrangement is in general just a bad design for a horizontal centre channel...
Here the answer from their chief engineer Ian Colquhoun:
trade off here is how to maintain a balanced left to right response while keeping the output from the speaker as close as possible to the screen

 

[Dustin B]

Well, I guess I'll defend myself a little here
I'd think Dr. Joseph D’Appolito would disagree. He is the guy who invented the vertical MTM layout, and even he doesn't use the horizontal MTM layout in the center channel he designed for a DIY Audax speaker set (if you have some basic woodworking skills and some tools, it will cost your $600 + enclosure materials to build the full 5 speaker set).
Here is a quote from his write up on his design:

The center channel speaker forms the heart of a home theater system. It defines the focal point for all cinematic action. The center channel speaker must have uniform horizontal polar response over the viewing region both to preserve the spectral balance of spoken dialog and to center the action for off-axis viewers. It should also be essentially a full range system.
To this end, the center channel is a 3-way vented speaker. A Micro Series™ tweeter and 5.25" mid-bass driver are vertically aligned and placed on the centerline of the speaker baffle to handle the high frequencies and the midrange. A pair of 6.5" woofers flanks the tweeter and midrange drivers. Crossovers occur at 400Hz and 3.5kHz. On-axis frequency response is within +1.6dB from 100Hz to 20kHz. The low frequency -3dB point is 55Hz and sensitivity is 87.5dB/2.83v/1m. At typical viewing angles within +15o off the on-axis position, response changes less than 1dB over the full frequency range.

And here is a link to the full article:
http://www.audax.com/doit/us_ht01.shtml
I still haven't a clue how the layout of the VP150 would address the lobing issues of a horizontial MTM layout from the second link. The only thing I can see putting a pair of tweeters that far apart doing is making the problem worse.

 

[Steve WC]

Maybe future and present Axiom owners not happy with their VP100's could get together via Marc H And purchase a bunch of M3ti pairs, with each person taking one for their center.

 

[Dustin B]

Quote from Axiom's website:

At your request, we have made the M3 available as a single speaker, so that you can add just one to your home theater. A great option for 6.1 speaker systems.

 

[Steve WC]

So, would the M3ti be a better choice than the VP100???

 

[Brian Bunge]

Steve,

I would take a two-way bookshelf speaker standing upright over an MTM speaker lying on it's side as a center channel every time.

Brian

 

[Derek_O]

I've been pretty happy running my M60s phantom center but if I was looking for a center channel I'd be keen on one built like that 3 way design Dustin pointed out, matching drivers and all. I wonder how hard it would be (if I was a DIY'er and needed a CC) to build one along those lines, strip down a M60 for parts and put em in a DIY cabinet. Something I'll have to think about down the road because I've been having trouble seeing how either the VP100 or VP150 would match up with the M60's because of the mix of the drivers.

Looking forward Rick, to hearing how you like the M3 as a center.

 

[Dustin B]

It would be very hard to strip down an M60 and just build a speaker like the one I linked to. Drivers, enclosures and crossovers are all very closely linked. You can't just drop a driver into another enclosure. Without the T/S specs of the drivers and a good knowledge of crossover design it would not be just hard, it would be impossible.

It is possible to make some very cheap drivers sound very good with a well designed crossover. I'm talking tweeters and midwoofers in the $10-$20 each range. Done well you could probably match or beat out anything in the sub $500 commercial range. It's also possible to take extremely capable drivers and make them sound like crap using just a cheap generic crossover.

 

[Rick Radford]

>Looking forward Rick, to hearing how you like the M3 as a center.<
Hope you're not holding your breath, Derek. I'm sorta slow getting around to this test.
It's no big deal to do it.. just gotta make the time.
Frankly, i don't envision using the M3 as a center other than for test purposes. I don't think the aesthetics make for a permanent fix (for me), regardless how good it may be. But I may well try a VP150 as it will fit where the Vp100 does right now.

 

[Derek_O]

Dustin said:

It would be very hard to strip down an M60 and just build a speaker like the one I linked to. Drivers, enclosures and crossovers are all very closely linked. You can't just drop a driver into another enclosure. Without the T/S specs of the drivers and a good knowledge of crossover design it would not be just hard, it would be impossible.

Forgive my lack of knowledge from a DIY standpoint but by stripping down an M60 you already have the crossover and ports and by doing some measuring you have the enclosure sizes and an idea of how Axiom shapes it box. Doesn't that get you something? I didn't mean it would be easy and it would take some work (mental and physical) and some trial and error but I think it might be an interesting experiment if a person had the time and money to work at it. I don't at the moment but that's a different story.
Rick,
I'm in no rush at all. With a sub to get yet, upgrading my surrounds, adding an RPTV etc........center channel stuff is way on the back burner. It'll just be some good information to have to refer back to.

 

[Dustin B]

What you are missing is the crossover is designed for the current baffel layout. You have to change the position of all the drivers and the shape and size of the baffel to do what you propose. This will require changes to the crossover to get optimum performance. It may work, but $800 for parts to build this center with an unoptimised crossover seems like a bit much to me.

 

[Ron Reda]

Using an M3 as a CC is not aesthetically feasible in my application, so my answer is pretty obvious...VP150 all the way!

Anyone want to buy a used, but babied (6 months old) VP100???

 

[Derek_O]

Dustin said:

What you are missing is the crossover is designed for the current baffel layout. You have to change the position of all the drivers and the shape and size of the baffel to do what you propose. This will require changes to the crossover to get optimum performance.

Ok. I was under the impression the crossover had to do with the drivers alone and had no idea you'd want to change the crossovers based on changes to the cabinet (keeping the internal volumes the same). My mistake.

 

[Dustin B]

I had no idea how important and complicated a crossover was when I started. I still wouldn't even dream of attempting a crossover design at the present time. You should have seen me a year ago when I was throwing together combinations of drivers and asking if this would make a good 3way DIY option, but I did eventually learn :p)

 

[Derek_O]

If dustin catches this thread again this would be for him.
I guess this is what you were talking about the drop in mid-low range frequencies as you approach the side of the cabinet.
http://www.speakerbuilder.net/web_fi...es/BSC/bsc.htm
http://www.trueaudio.com/st_diff1.htm
Since I don't think you'd be able to stack the tweeter and mid-range in the present M60 cabinet width you'd have to have a wider cabinet. Then all drivers would be dealing with a wider cabinet and the mid and tweet would be off the center of the cabinet thus having a smaller baffle on one side. I can see then why you might end up with a different response from the original M60. Plus cross-over design isn't just about selecting the cross-over points but compensating for the difference in raw output levels between the different drivers. That hadn't occured to me.
It's an interesting problem though and one I may look into some more through some of the free and demo speaker software out there. Just to pass the time.