Axiom Home Page Forums General Discussion Technical Questions Ian (or Alan), question about VP150 design/layout

Hello,

I was wondering if you could comment on some concerns raised about the VP150's layout that were posted in the following two threads on another forum:

http://www.hometheaterforum.com/htforum/showthread.php?s=&postid=760710
http://www.hometheaterforum.com/htforum/showthread.php?s=&threadid=73607

Some people seem to be arguing that the TMMMT layout of the VP150 would improve off-axis performance of the woofers, but at the expense of poor performance of the tweeters.

Given Axiom's reputation for building excellent speakers I wouldn't expect your top of the line center to have a serious design flaw, so I'm guessing maybe there's a little more to it than those threads would indicate? Would appreciate any clarification or explanation you could offer.

Well i'm not Alan or Ian but just offhand i would tend not to listen to a guy who says the design of the speakers are flawed when he himself uses JBL speakers bought from A&B sound and was thinking about 'upgrading' to PSB Image2s from A&B sound (chek out their profiles and webpages). I won't even get into his atrocious grammer and spelling (e.g. His quote: "My enough knowledge to be dangerous tells me this layout is a bad idea.").

Another guy quotes:
"Remember I built an almost identical sub to theirs? [axiom] I think it could mate well with some little full range drivers for a Bose-Buster system. But for what they're [axiom] charging for them I'd agree that they're pathetic. [axiom subs] They don't even use 3/4" MDF"
Correct me if i'm wrong but i thought the Axiom speakers WERE all 3/4" MDF (info taken from a recent Ian post on the composition of the new M22s and extrapolated it to all the Axiom models).

Secondly, this guy actually refers to Bose in the same sentence as if Bose were actually a decent speaker.
Oh please, you cannot compare those brand names to Axioms. Bose spends more money on marketing their product than they do on R&D which says it all.

If these kids are going to doubt the speaker design then they should at least LISTEN to the speaker first before criticizing it since it sounded as if none of them have actually heard the VP150. They should also be comparing the Axiom designs to other equally 'reputable' speaker companies (e.g. Monitor Audio and B&W) and not Future Shop specials.

This third guy only quotes specs and then says: "What a weak center. I'd aviod this like the plague just from these alone."
Again another non-listening opinion.

Then this dope chimes in with:
"And don't forget the cheap cabinet materials!"
Once again, apparently has never even seen the Axiom speaker. As far as i can tell the cabinet material is the same stuff (and good heavy material) that makes a solid cabinet.
I REALLY hate uninformed, illogical, unexperienced opinions. SHOW ME THE PROOF!

This last guy was a bit weird though and quoted some jargon about speakers.
"WRT the Konar vs D'Appolito view of MTM lobing, a high res TDS plot tells the tale doesn't it, so what's to debate? ?
Does that really mean anything?

Well, I wouldn't immediately dismiss all JBL speakers as garbage...

I agree there's some "noise" in those threads from opinionated people who may not know what they're talking about.

But there are one or two people in the second, older thread who sound somewhat knowledgeable. And now that I think about it, if having too much distance between the woofers can hurt off-axis performance, why wouldn't the same thing be true for the tweeters?

The TMMMT design provides better imaging with the two tweeters in the outboard positions, and reduces suckouts common with the MTM d'Appolito design.

The overall presentation of Axiom's design is more open and natural than the d'Appolito design, providing a more realistic and dynamic listening experience.

And for the record, I don't own Axioms yet. I have heard them and very much enjoy them, and as soon as I can sell my Paradigm Monitor 11 based HT system I will make the move to Axiom.

Yes i normally would not lump all of one brand into a category and make a summary decision on their quality but from the JBL 've heard i think they are pretty low brow.
They make speakers for the masses, not for quality, in my humble opinion.

I personally feel that PSB and Paradigm have also moved into this 'make for the masses' category although they both started as very good companies, years ago, and i would buy PSB and Paradigm over Bose, JBL and some other select names.

Its the little things that make the differences that show quality still survives with some companies while others try to cut costs by using cheaper materials (e.g. felt surrounds vs. rubber, polypropylene cones vs. real metals).
I have alot of confidence that Axiom is still producing quality speakers. I'm sure Ian's design of the VP150 has some merit and was not just an idea that popped into his head one day without more extensive thought or testing.

In any case, you still can't dog a speaker design until you've heard the speaker. It just doesn't make sense.

johnk

if you are going to listen to anything not from Alan or Ian, please, listen to this.

I have the VP150 and it's one of the best centers I have ever heard. I have the Fifth Element superbit, and that Opera scene at 'full blast' is @(^($@ incredible! Her voice, even at the highest frequencies, just sail across my living so gently and swiftly, never hitting a foul note, never sounding fatiguing or annoying. Trust me, I am EXTREMELY picky about sound. My receiver also has a 5 channel stereo option, and classical music with this on definitely sounds great out of the center. Off axis performance is also amazing. I have M22's, M3's, and VP150, and I think the VP150 has the best off axis performance of the three.

It may exist, but i haven't seen one yet. A bad review of an Axiom speaker from a reputable source (i.e. sound & vision, goodsound, soundstage, etc.), and i dont want to hear that CNET crap, they had nothing but good things to say about the speakers, but inexplicably (sp?) gave it a low rating. Thats where the real test is, not some uninformed self-appointed expert.
sorry about the rant but i am uterly impressed with my speakers.

Kore

Hey chesseroo,

I took a look at that forum (link) and I just gotta say, that is one hell of a brain trust going on over there. Scary, isn't it?

CAV104

Well some of them appear to be trusting on something affecting the brain.
Geez that one guy spouted so much jargon and unknown abbreviations i swear he's a couple of marbles short of a bag.

I am awaiting the day that some knob puts out a forum thread stating that leaving a toenail clipping on the top of their speaker drastically improves the sound.

Wait a minute, I thought a toenail clipping DID improve the sound. Reduces clipping, don't you know.

That's on top of the amplifier, not the speaker.

In reply to:

---

I have the VP150 and it's one of the best centers I have ever heard. I have the Fifth Element superbit, and that Opera scene at 'full blast' is @(^($@ incredible! Her voice, even at the highest frequencies, just sail across my living so gently and swiftly, never hitting a foul note, never sounding fatiguing or annoying. Trust me, I am EXTREMELY picky about sound.

---

I also recently purchased a VP150, along with a pair of M60ti's, M3ti's, and a single QS8. Part of the reason that discussion caught my attention is because the VP150 hasn't quite lived up to my expectations. Sound from the center channel sometimes seems to have a slightly hollow or "boxy" sound to it, and maybe a slight rolloff in the upper freqencies. Dialog also seems strained at times, sometimes even to the point of slight distortion that sounds like crackling or static. Note I'm not even talking about off-axis performance here, this is from the sweet spot. The other speakers are very impressive, particularly the M60's which have given a new life to 2-channel music; so I don't think this is just a matter of me expecting too much from the Axiom speakers. The way I see it, there are three likely explanations for my disappointment:

1) My VP150 is somehow defective. Thing is, it's not obviously broken, so I don't know if it's possible for the speaker to have a defect that hurts performance without making the speaker inoperable. Also, I really don't know of any technical test or diagnostic I could use to determine this.

2) The VP150 just doesn't perform up to my expectations. On the other hand, given the price of this top center from the Axiom lineup and the fact that I'm very happy with my other Axiom speakers it seems like this center should suit my needs well. That's why when the discussion about the design of the VP150 came up on the other board it caught my attention.

3) Source Material. I suppose this is possible given that sometimes the VP150 seems to sound better than others. I would even expect this if I were just getting disappointing from analog cable TV. But that's not the case, as I'm seeing these problems with DVD's that I would consider to be reference material. You mention 5th Element Superbit; the scene where Leloo escapes from the lab and jumps off the building has always been demo material for me, as well as the scene where Gary Oldman's character demonstrates the new gun. Both of these scenes exhibit the problems I mentioned above. And the other night when we were watching Mothman prophecies there's a scene towards the end where it's totally silent except for a phone ring coming from the center channel, which had noticeable distortion/crackling. But then last night watching Disney's Atlantis the sound was very good. So I don't know if Atlantis is just a less-challenging soundtrack for the center, or do the recordings on the other two movies contain distortion?

The one thing I am sure is that this is not an issue of inadequate amplification or clipping. I'm using an Outlaw 770 amp with 200W/channel @ 8ohms (300W @ 4ohms), so it should be plenty of power considering I watch movies at 6-10db below reference level (usually 10).

In reply to:

---

My receiver also has a 5 channel stereo option, and classical music with this on definitely sounds great out of the center. Off axis performance is also amazing. I have M22's, M3's, and VP150, and I think the VP150 has the best off axis performance of the three

---

Interesting, my old Denon had 5-channel stereo, and my Rotel 1066 has 7-channel stereo. About the only thing good I can say about these modes is that they're loud. I much prefer plain old 2-channel or maybe ProLogic-2 for classical music, both of which do a better job of preservering the soundstage and imaging of the recording.

A very interesting quandry indeed.
I guess the only way to sort out the potential problem is to poll some other users with dvds and the same videos (with the same hookups as well, rca vs digital) to clarify whether these sounds can be heard with anyone else's setup.
You could also possibly switch out your Outlaw with something else to remove the receiver as a possible source of the distortion.
Of course there is always returning it to Axiom for a look see but offhand most broken drivers are relatively easy to hear and determine that a replacement driver is needed.

Can you isolate the distortion to any one particular driver or 'area' of the speaker? Or is the distortion actually 'in' the sound?

I'm planning on buying a VP150 in the next month myself and stories like this make me a tad nervous (obviously due to the $$ spent more than anything).
Let me know how things turn out.

I recently set up my new VP150. Listening to Diana Krall's DVD for the first time, I heard definite buzzing and distortion from the center channel. I took off the grill and listened, and I could isolate the sound to the right-most woofer, which was buzzing on each note from the string bass. I hadn't heard this on other DVDs but the soundtracks hadn't been as detailed.

I assumed that it was defective, and I could still send it back in my 30 days. I replaced it with my old cheap center, but after listening for a while, wanted to compare again to the VP150 - and the buzz was gone. Don't know if it was a short in the cable connection or what, but I can't hear it anymore. I think the 30 days is ending soon; hopefully the buzz won't return.

ChrisR

Chris, your experience sounds similar to mine, and I think your description of "buzzing" may be a better term for what I'm talking about when I say "crackling". Maybe it's a questionable wire connection, I'll check that when I get home.

BTW, I don't want to paint too negative a picture about this speaker, because it is better than my previous center. The occasional boxiness/boominess I mentioned is somewhat subtle, and I have a feeling that it is related to the source material, because it only seems that way occasionally. It's the distortion/crackling/buzzing that concerns me most.

PS - What's this Diana Krall DVD you mention, I've heard her name come up several times when people discuss reference/test material. Searching amazon.com I see "Live in Paris" - is this the DVD you're referring to?

jkohn,

Live in Paris is indeed the Diana Krall DVD concert, and it's excellent. The DTS mix puts you literally right on the stage... the piano is played in the surrounds, and the guitar is so ridiculously forward in the left/center you'd swear YOU were playing it.

jkohn & Chris,

I had (what I think is) the exact same symptom in my VP 100 that you describe for your 150's. It wasn't noticeable during the movies or music I had played up to that point, but was very evident during the subwoofer crossover check calibration on the S&V disc. I thought I'd broken something within my first week, but while talking with Joe V, I was able to localize the "giant mosquito buzz" to one of the woofers. He had me check for dust on the cone, and while gently pushing on the rubber "boot" surrounding the woofer, the sound miraculously went away. I was thinking it could be a short of some kind since I was able to recreate the buzz by pushing again on the boot. I pushed on the boot one final time to make the buzz go away, and all has been good for over a month now. Joe shipped me a new woofer, but I haven't installed it yet because the "buzz" hasn't returned. Somewhere online (this forum or HTF), a poster mentioned tightening the hex screws around the woofer/tweeter on his Axiom speakers as they were a bit loose. I checked mine and the screws on my center were a bit loose. I tightened them up "just to be sure", and haven't had any problems.

I'm no speaker expert, but your symptoms sounded exactly like what I experienced. I don't know if I have (or had) a short or a loose connection, but things worked out great in my case, and I continue to be blown away by the performance of my system. Good luck, and give Joe a shout if you still have problems.

lando

Lando, thanks for the little snippet of info.
After all this hubbub about buzzing, i went downstairs and played with my M60s for a bit.
Since i'm still in the auditioning stage i'm being extraordinarily thorough about scrutinizing any odd sounds before committing the actual purchase to a permanent one.

I played 2 songs, "I can see clearly now" by Holly Cole Trio and "New Age" by Tori Amos (first couple of seconds of each song has bass tones to push the lower end, esp. the Tori Amos song).
Lo and behold, there is a mild buzzing radiating from the lower woofer at each beat. It only goes away when i turn down the volume but the woofer should be able to handle that sound without any problem at the volume i was using (around 65%-75% max volume). Both woofers on the left and right speakers make the noise although the right speaker is more noticeable.
I will read through your post again and see if there is a simple fix as you mentioned but so far i'm not impressed by having to fix anything at all.
For several grand for an entire system, buzzing is NOT acceptable. I'm hoping i don't have to return these M60s before the 30 days is up because i do like alot of things about them so far.

An addendum to my last post:

I just did the screw tightening, lint looking and touch rubber tests but to no avail.
It seems after the screw tightening the buzz decreased a bit but i could not get it to go away. It only comes around with certain frequencies of lower range sound (as in the 2 previous songs mentioned).
After very gently pushing on the dust caps (not while music was playing) i did notice that the woofer cone sounds like it is hitting something behind it. The woofer cone in the left speaker did not have that same sound when gently pushed and its buzzing sound was also noticeably less (as previously mentioned in prior post).

During my close inspections I also just noticed a small flaw in the vinyl near one of the woofer edges. It almost appears as if the woofer was replaced once already, or perhaps someone had a bit of trouble getting the original woofer in there in the first place. A small chip of vinyl about an inch long around the edge of the woofer inset on the cabinet has lifted away a touch from the underlying MDF.

I'm very unhappy.

Chesseroo,

I saw your posts and feel for you about your buzzing. Again, I have little speaker knowledge so please don't take my earlier post as the best solution for anything. In my situation, the buzz in my VP100 hasn't returned, and I remain confident that I have the best system for my money. Good luck!

lando

I think it is important to remember when listening for buzzing and crackling noises that the speaker is going to reproduce whatever information or noise may exist in your entire system right back to the original recording. This goes to every wire connection, solder joint, antenna hook up, ground wire, and electrical component through the whole system. If the speaker is the culprit then the noise will be mechanical in nature, which generally means that crackling type sounds are not the speaker. A mechanical noise will generally seem to add an overall distortion to the sound at volume levels that are definitely below clipping. This is usually pretty easy to notice when listening to music. For jkohn's particular issue with the VP150, there seems to be something wrong here for sure. We would be happy to bring your VP150 back to our lab for a thorough test and either fix your problem or least be able eliminate the VP150 as the source of the problem. There is absolutely no way with the power you have that there should be any distortion from the center channel, unless of course you are running into clipping. The VP150 can take the 200 - 300 watts you are powering it with no problem. In fact I run my own with more power than 300 watts and our power tests are done on the VP150 with a 620-watt amplifier. Please contact us directly at the toll free number 866-294-6688 or at advice@axiomaudio.com and we will look after all the details for you.

Going to the original post that started this thread. There seems to be quite a bit of confusion over how identical parts interact with each other (the two tweeters) in a room environment. The comment about comb filtering is a red herring. This effect can be measured in anechoic environments but it is not an audible reality in the room. If it were we would have all dumped stereo a long time ago and would be listening to mono again. The off-axis lobing effect of the tweeter and woofer is a reality in the down-axis measurement of all speakers that use a tweeter above the woofer, and does create an interesting dilemma with center-channel design because this phenomena now exists in the right and left off axis in a WTW layout. As to how big an issue this is in the real world is best determined by double blind listening tests. It is audible, especially when seated far off axis from the TV, but always surprised me as to the how slight the effect in the room is when compared to the measurements. A testament to the importance of the family of measurements as opposed to the single axis you are directly seated in. The VP150 driver layout does eliminate this issue altogether by effectively not having this particular axis no matter your seating position. The result is excellent, and it has been proved out in our double-blind listening tests. In fact it was so impressive we actually changed the VP150’s driver array to this layout mid-stream from a WTWTW layout.

I'm having a similar problem with my M30s. I would occasionally notice a buzzing sound out of my right speaker. I tightened down the wire connectors and also tightened the screws, but the sound is still there. While listening to a Peter Gabriel CD, there was a particular song that kept causing the buzziness. The sound was most noticeable from the back, coming out of the port. I eventually found that as I was turning the speaker, to hear where the sound was coming from, it would actually quiet down and even go away as I would turn the speaker over. Tapping on the sides of the enclosure seemed to have quieted it down, but it is still there when upright. It definitely sounds like there is something in the enclosure that is vibrating at certain frequencies. I have both speakers upside down now and that seems to have temporarily fixed the problem.

Other than the occasional vibration sound, the speakers do sound good, especially with high quality recordings with a nice dynamic range. I hate to have to go through the trouble of returning them, but if the sound continues after I put them upright, I'll have no choice.

This is my concern, that the noise sounds mechanical, a definite buzzing right after a musical note. It is not an electrical type crackle or anything that sounds wire related.

I figured that the speakers should easily take the power my receiver feeds it so i know that the volume thing should not be the issue esp. not at 75% of max. I am well away from the clipping zone.

I will give Joe a call today i guess and see if he can hear it through the phone. After listening again last night, i'm positive that 2 of the woofers (low one on the left and mid one on the right) both make the noise.
A friend is coming over today who knows a bit more and can confirm for me it is definitely a mechanical issue or not.

Thanks Ian. I hope this all works out. I really do like the speakers a whole ton.

So here's a whole new question, perhaps a new thread, who does these double blind test at the lab?
People off the street?
University students hired for a day?
Because i think it would be really fun to visit Ottawa someday, drop into Axiom and sign up for an afternoon of blind listening testing.
Can just anyone do that or do you have to be a certain height to get on the ride?

here's my reply on everything in this thread:

1) I have the Diana Krall DVD in DTS, and I do NOT hear a crackling/buzzing sound out of the center.

2)I have occaisionally heard strange sounds out of all my speakers, but they were only repeated by playing the exact source material, therefore, the source is at fault

3) your Outlaw, what ohm switch do you have it at? 8 or 4? According to Outlaw, a 6 ohm speaker should have it at 8, I believe, but I'm not sure.

4)Fifth Element - Superbit is good for reference, as is the Nine Inch Nails live DVD in DTS, and that crappy Star Wars movie. The pod race scene is just excellent in audio.

5) 5 channel audio is loud, I only like it when not critically listening, and just listening for loudness. Otherwise 2 channel beats it anyday. I'm not the biggest fan of DPL2, maybe i need to get used to it.

6) do NOT try to make your VP150 play any deep bass. Mine's cut off at 80 and it sounds better like that. Set to Large, it distorted, especially at loud volumes.

Good luck with your difficulties with your centers

Well, last night I re-did the cable connections and also checked the screws on the center woofers and tweeters. For every driver there was at least one screw that could stand to be tightened. However on one of the tweeters two of the screws would not tighten down at all no matter how much you turned them, apparently the threads are stripped which concerns me somewhat.

By the time I did all this my wife was in bed so I didn't get to re-check for the sound issues. I'll do some more listening tomorrow and if the problem persists I'll contact Axiom to see what we can do.

Ian,
Just curious about the lobing you (and other reviewers) refer to. Can you either describe what this effect sounds like or give a short (astrophysics type dissertation) description on what is happening with the frequency interaction?

Thanks!

Randyman