Axiom Home Page Forums General Discussion Advice from Axiom Owners M80 and VP150 Testing over at Sking Ninja Forum

I'm sure it's their overactive protect circuit. It's only in the amps people have reported problems with, and the ones that don't have it, M80 owners seem quite satisfied with.

I couldn't swear to it Peter since it's been a while but my recollection is that with the XPA2 and M80s with an 80 hz crossover setting the protect circuit did not trip, the results are probably in the thread I started on that topic but the point is probably moot, because I did not test the crossover issue extensively since at that time I was waiting for an 800 to be built and was not that intrigued by the possibility of discarding the LFEs entirely, and the prevailing opinion at that time was that the supposed dip below 4 ohms question was not a real issue, e.g., Alan stated that the 80s were a nominal 4 ohm design with no dip below 4 ohms across the audible range, I suppose it did not occur to me at that time that the audible range is typically defined as 20 Hz - 20KHz and that the problem might be in the range of 10-20 Hz.

“The real alarming part though is that the mids have no high pass filter at all. They are only crossed over to the tweeter and allowed to play as low as the lower end roll off allows. Not only does this mean that they will easily reach exertion limits with low frequency information but that they also contribute to making the impedance in the lower range even lower.”

Can anyone verify this? It can’t be accurate!

I'm sure the design information could be accurate. However, his analysis could be completely wrong.

Axiom didn't stay in business this long (lacking the marketing power of Bose) or get this dedicated a following by not knowing how to design a speaker.

I really didn't pay attention to the M80 graphs since I don't own any. I did look at the VP150 graphs and was concerned.

I have previuosly stated on this board that the VP150 had not lived up to my expectations. Of course that is in comparison to my M22s and QS8s; both of which I am completely happy with. On another thread I recently mentioned that I have the VP150 on a shelf below my LCD TV and had recently turned it over so that it angled up toward ear level. That has made a positive difference and movie dialog is now generally better and satisfactory.

Still the graphs did concern me. If the graphs were accurate then no placement of the VP150 would give satisfactory performance off axis in the normal home environment. There are too many satisfied VP150 owners for that to be likely.

I am a retired engineer (BSEE, MSEE) but mostly computer background and don't own expensive audio test equipment. Still my old Pioneer VSX-45 does have MCACC so I decided to make use of it. It's an older generation MCACC and takes equalization measurements at 63Hz, 125Hz, 250Hz, 4kHz, and 11.3 kHz. Since I have crossover set at 80Hz the 63Hz does not apply.

I made equalization measurements at 5 different room seating locations from dead center front up to 45 degrees off axis. What I found was no more than 4 db difference across each set of frequency measurements. Correcting for trim level the 125Hz ranged from -5.0 to -4.0, the 250Hz from -5.0 to -4.0, the 4kHz from -2.5 to +1.5, and 11kHz from -1.5 to +1.5.

My results were very different from the ninja graphs which show ranges of over 15 db difference off axis. My results can be explained by room variations even if the VP150 were a point source and had perfect 360 degree dispersion. I don't know how to explain the ninja graphs; but something seems very wrong.

In the text with the ninja graphs was the statement " What the listener will really hear can vary greatly even from one ear to the next." Again there are too many satisfied VP150 owners for there to be any truth in that statement. Bottom line is I have to totally discount the ninja information about the VP150; and believe my experience and my ears.

Did he do the graphs in an anechoic chamber, or did he just use a room in his office or something?

I was curious about that, too.

In the M80 section of the ninja report it says:

"All measurements were made by Danny Richie at GR Research. Danny has been contracted as an outside party for measurements before and has an established reputation in the community for high quality work that is beyond reproach."

Of course my concern is how speakers perform in my home and the VP150 performs well. It would perform even better if I could place it in the center of my TV screen, but then I would miss an important part of the picture.

I really don't care how the ninja graphs were arrived at. I have done enough to allay my concerns about the VP150 in my home.

Bill

If someone is looking for a specific "result", the tests can be made to accomodate the result.