Axiom Home Page Forums General Discussion Home Theater Just got the spl meter. Need help.

Honestly I think Alan should read up on Audyssey, it is a totally different technology than past years setup routines in receivers, and blows Trinnov out of the water if you read the reviews by many. Speaking highly of the THX founder on other issues, but not this creation, is not fair. It made a HUGE difference for my room and made my Axiom great speakers sound even better, as it factors in the rooms characteristics in the time/space domain.


When I cycle between it off/on it is night and day better.

OK...here are a few randomly related thoughts.

Imagine this scenario...

We work very hard to turn out an absolutely gorgeous pair of speakers. The owner, wanting to get the best performance possible out of them, rushes out and purchases a Radio Shack SPL meter. He locates a table of calibration corrections on the internet and carefully makes measurements, applies the corrections and plots a graph. It looks terrible. He thought the speakers sounded great when they arrived, but the measurements indicate something is terribly amiss. He contacts us in panic. His speakers are certainly defective and he has the graphs to prove it.

"How do they sound?", I ask? "They sound fine," he responds.

If he had just avoided that Radio Shack purchase, he could blissfully enjoy his speakers. The problem isn't with his speakers. The problem is with his measurements. But at least on a temporary basis, it ruins his listening experience.

Unfortunately, this is a common occurrence and one we have had to deal with far more often than we would like.

Here's another...

A person uses a speaker measuring system to measure his speakers. The bass response is terrible! It falls off early and there are ugly peaks and valleys in the response. There must be something dramatically wrong.

So I ask how the measurement was done. He indicates it was done at the listening position. He goes on to say that no matter where in the room he takes the measurements, the graphs vary somewhat, but not that much. There is clearly a problem.

I explain to him that he was measuring the room. Unless you take near field measurements at the driver, there is no way to obtain accurate measurements below about 200Hz. If the measurement times are long enough to measure the bass response from the listening position, you are also measuring the room.

Room measurement tools like REW (and even a Radio Shack SPL meter) can be very useful in terms of optimizing your room. But they will not provide an accurate indication of the performance of a speaker. For that you need a quality speaker measurement system and a well-calibrated measurement microphone. And you also need a good bit of time to learn proper techniques for using these tools.

Too often, these tools do more harm than good. Improper measurement technique and a failure to understand how these tools work can cause you to needlessly lose confidence in your audio equipment.

As long as I am on a roll, I might mention reservations I have with all the new room EQ functions in receivers these days. I can't tell you how many times I have asked customers to turn off the EQ function and just use the speakers as they are. In almost every case, they reported a dramatic improvement in performance.

This would not seem to make sense. Here we have a magic electronic gadget that can correct for any flaw in the speakers/room and do it at the listening position. But all too often, it simply doesn't work.

On quite a few occasions, I have used DEQX (a very powerful and capable system) to apply a simple correction to a single loudspeaker. In other words, I was not using it as a crossover, just using it to measure and correct for anomalies in the speaker performance. In almost every case, the speaker performed far better without the corrections.

IMO, the only thing an automated receiver EQ system should be used for is to deal with room modes. It should not touch the signal above, say, 100Hz. The only thing it can do at higher frequencies is screw things up. I am very confident that the speakers we produce have absolutely no need for correction. There simply isn't anything to correct.

Any issue that does require correction is room-related. Changing speaker performance in order to deal with poor room acoustics is, plain and simple, a very bad idea.

The right technology, applied correctly, can be extremely beneficial in achieving great system performance. But sometimes technology can be a curse. It seems like every major receiver manufacturer today is offering an auto-EQ function. This may be great marketing, but in many cases, it is a terrible use of technology. Others may disagree with this advice, but if you have a function such as this on your receiver, please turn it off. In most cases, you will be a lot happier.

End of diatribe.

- Jim

Honestly I think Alan should read up on Audyssey, it is a totally different technology than past years setup routines in receivers, and blows Trinnov out of the water if you read the reviews by many.