VMPS vs Green Mountain Audio...

Audiobudha · « **on:** 23 Jan 2004, 08:11 pm »

Has anyone here heard the VMPS RM-40, Elixir and also the GMA C-3's? I'd love to see these in a shoot out. VMPS owners rave about their speakers and so do GMA owners. It is really a difficult comparison because one is a hybrid (VMPS cones & ribbon) and the GMA's are a phase and time correct cone design.

Anyone have any thoughts or opinions?

JoshK · « **Reply #1 on:** 23 Jan 2004, 08:14 pm »

Quote

GMA's are a phase and time correct cone design

I am sorry I have to say but time coherency is marketing propaganda.

maxwalrath · « **Reply #2 on:** 23 Jan 2004, 08:19 pm »

I don't know, JoshK. I had a pair of Kestral Hotrods that sounded REALLY good, and they don't exactly use expensive drivers.

meilankev · « **Reply #3 on:** 23 Jan 2004, 08:27 pm »

AudioBudha,

I own RM40s, and have had the opportunity to listen to a pair of GMA speakers on three occasions (4 hour seesions each). Unfortunately, the GMAs my friend owns are the smaller Europas, which he drives with a Cary tube integrated amp. He also supplements the Europas with subwoofers.

His previous speakers (which I also had extended sessions with) were Kosalas (by Adire Audio). On my first two exposures to the Europas, I felt they were a step backwards from the Kosalas. But the third time, they sounded much better. While my friend had tweaked his system some, I feel the main difference was that the speakers had finally broken in fully. the high-end glare had disappeared, and the imaging/soundstaging was much improved.

All in all, they were very nice, and a great deal at their price. Alas, I have never heard their big brothers.

For what it's worth, another friend of mine here (listening buddy) has hear them, and he didn't care for them. But from what I can extrapolate from my time with the Europas, I would venture that the entire family line can sound wonderful in the right system. Perhaps the C-3s my friend heard had not broken in yet.

I apologize that I don't have the exact info you are looking for.

Kevin

mattybumpkin · « **Reply #4 on:** 23 Jan 2004, 08:31 pm »

Joshk,

And I suppose you have adequate technical information to support your claim?

I guess Roy of GM and Richard of Vandersteen and Jim of Thiel don't know there stuff....

"M"

Tyson · « **Reply #5 on:** 23 Jan 2004, 08:51 pm »

martybumpkin,
I'm not taking sides here, but your argument holds no weight simply on formal logic terms. It commits a falacy known as argumentum ad verecundiam, or appeal to authority.

Sometimes the appeal (or reliance on authority) can be a valid argument, when there are 2 factors - 1, you and your audience are ignorant of the specific knowledge you are relying upon the authorities for, and 2, there is a general agreement or consensus among authorities about the issue being discussed.

You may or may not be meeting point 1 (depends on the knowledge of the audience), but I can say for certain that you do not meet point 2, as there are MANY well respected designers that don't use time/phase coherency.

You may agree or disagree with them, that is not the point. The point is that a general consensus does NOT exist among the "experts", so therefore you cannot use the "experts" to bolster your point.

Just pointing this out for what it is worth.

Redbone · « **Reply #6 on:** 23 Jan 2004, 08:58 pm »

Man it has been a bad week, and man did you make me smile Tyson. Very basic logic, philosophy 102 or something. How about the A implies B stuff ? "It is always cloudy when it rains. It is cloudy. Therefore it must be raining".

BTW, the dog in my avatar is real, alive and named Tyson.

JoshK · « **Reply #7 on:** 23 Jan 2004, 09:03 pm »

Tyson,

Very well said, actually I was going to say that in science you don't disprove a claim and assume it is correct until it is disproven but rather the other way around. I am not the one making the claim in this instance. It is up to those that believe in time coherency to prove its worth, not the naysayers.

All that said, correcting for time can be done for exactly one point in three dimensional space. Move a little off that point and it all goes to hell. So then how is the designer suppose to correct for a point that will work for all peoples, both farfield and nearfield setups?

Marbles · « **Reply #8 on:** 23 Jan 2004, 09:09 pm »

Quote from: Redbone

the dog in my avatar is real, alive and named Tyson.

Most of us have known for a long time that Tyson is a dog.

Q · « **Reply #9 on:** 23 Jan 2004, 09:30 pm »

It is now painfully obvious that Tyson is a lawyer...(or wants to be).

While true that time coherence cannot be fulfulled by multiple drivers in more than one point in space, designers do properly go to great lengths to ensure that drivers, especially near the crossover points, are moving in phase, and coherent in time. By this I mean that with an improperly designed crossover, the drivers could be in phase, but delayed with respect to each other by 1/4, 1/2, or 3/4 cycle, or more.

For example, Lets say you have a crossover that delays a signal by 180 degrees. One could simply swap the +/- leads to the driver and call it "in phase" with the main signal. BUT, the drivers would not be time aligned. Moving one driver 1/2 wavelength( at crossover freq ) back from the other would tend to put you back "in time", but not at other frequencies.

JoshK · « **Reply #10 on:** 23 Jan 2004, 09:51 pm »

Q,

I do agree with this assertion....I was mostly picking on the blanket statement.

Tyson · « **Reply #11 on:** 23 Jan 2004, 10:00 pm »

Tyson is, or wants to be, a lawyer.
All lawyers are dogs.
Therefore, Tyson is a dog.

Actually a valid argment. I really am a dog

PS - I'm not really a lawyer, nor do I want to be one. Won't argue the dog point though

Audiobudha · « **Reply #12 on:** 23 Jan 2004, 11:57 pm »

I wanted to avoid a debate about time correctness and phase coherency. I was merely interested in a subjective review based on listening experiences.

If you really want to understand the issues surrounding time correctness and phase coherency within speaker designs I highly recommend everyone on this board take the time to read this AudiogoN thread. I've read it three times and picked out many good nuggets of information.

My biggest question regarding time correctness is this: On a stage the performers are situated at different depths; therefore, in most set-ups the sound waves of the guitar, bass and vocals are going to reach the listeners ears before the percussion instruments (drums, bongos, cymbols etc.), and keyboards. So, if this isn't a concern at a concert, why should it be a conern in your listening environment? Having said that, based on what I've read I think phase shifts are much more important in speaker design.

Check it out:
http://www.foodnetwork.com/food/recipes/recipe/0,,FOOD_9936_9361,00.html

Marbles · « **Reply #13 on:** 24 Jan 2004, 12:15 am »

The Stew looks very nice, and the "Fear and Loathing" quote is cool, the drugs must be kicking in for one of us, unfortuneatly they are not kicking in for me

What does stew have to do with this thread????

PeteG · « **Reply #14 on:** 24 Jan 2004, 12:28 am »

Quote from: Marbles

What does stew have to do with this thread????

I don't know but I'm hungry now.

WerTicus · « **Reply #15 on:** 25 Jan 2004, 12:09 pm »

Quote from: Audiobudha

...On a stage the performers are situated at different depths; therefore, in most set-ups the sound waves of the guitar, bass and vocals are going to reach the listeners ears before the percussion instruments...

Well... from a stage does the higher frequencies reach you before the midrange ones? i dont think so - all the 'bits' that go with each instrument come at the right time to the listener at once... so it wont sound truely real if your tweeter info is getting there before your woofer info from whatever instrument. one reason why single driver speakers sound so good... probably 'the reason'

audiot_savant · « **Reply #16 on:** 25 Jan 2004, 08:40 pm »

Audiobudha--In simple terms, the answer is that the placement of the live musicians has no bearing on this question. The sound of the instrument is being 'produced' by the single instrument entity, all frequencies of that (direct--not reflected) sound arriving at your ears at the same time .

However, in 'reproduction' the sound of the instrument is usually being divided amongst two or more drivers not occupying the same physical space and location, causing lack of coherence. Additional delays can be caused by the crossover components and the slope of the x-over.[/quote]

Audiobudha · « **Reply #17 on:** 26 Jan 2004, 04:11 pm »

audiot-savant & Werticus -

The different frequencies arriving at the same time makes sense in theory. I guess if I could see them it would be easier.

So based on your comments it would appear that time correct and phase coherent designs are important to you because they do a better job of reproducing "realism".

I guess I'll just have to audition both brands and see which one comes out on top in my own mind.

Dunedain · « **Reply #18 on:** 26 Jan 2004, 06:40 pm »

LOL! You've got to like that bizarre stew link.

Audiobudha: Good idea. I've never heard GMA speakers, so I can't comment on them. But
my money is on VMPS, just because they sound so fantastic.

It will be fun to see which
you pick and what made you like one over the other. Let us know what you decide to get.

brj · « **Reply #19 on:** 26 Jan 2004, 07:01 pm »

The speed of sound is constant for a given medium, regardless of frequency. For a given medium, however, the speed of sound will increase with temperature. (The speed of sound for a medium varies with the square root of temperature.)

However, could you imagine a really exacting orchestra conductor? "Tubas, you sit 12 feet behind the clarinets, so I need you to anticipate their tempo by 1.2 nanoseconds to ensure the audience enjoys a perfectly time-coherent performance!"

-Brian