This is a review and detailed measurements of the Yamaha NS-6490 3-way speaker. It was kindly purchased new by a member and drop shipped to me (back in spring no less!). They cost US $130 a pair on Amazon including Prime shipping. I think I found it elsewhere for just US $99 which is quite a low price for a 3-way speaker.
The pair of of NS-6490 come in a giant cardboard box because each speaker itself is far bigger than just about any bookshelf speaker you have seen:
View attachment 89599
Doesn't this look pretty and utterly marketable? Makes you think you are buying the famous Yamaha studio monitors with their white drivers.
Some of your dreams are dashed when you lift the speaker and notice that it is incredibly light especially for its size. Part of that has to do with very thin walls:
View attachment 89600
I must say, it has been decades since I have seen spring terminals on a speaker like this.
Measurements that you are about to see were performed using the
Klippel Near-field Scanner (NFS). This is a robotic measurement system that analyzes the speaker all around and is able (using advanced mathematics and dual scan) to subtract room reflections (so where I measure it doesn't matter). It also measures the speaker at close distance ("near-field") which sharply reduces the impact of room noise.
Both of these factors enable testing in ordinary rooms yet results that can be more accurate than an anechoic chamber. In a nutshell, the measurements show the actual sound coming out of the speaker independent of the room.
I performed over 800 measurement which resulted in error rate of slightly above 1% in the upper treble frequencies.
Temperature was 59 degrees F (yes, it is getting cold here). Measurement location is at sea level so you compute the pressure.
Measurements are compliant with latest speaker research into what can predict the speaker preference and is standardized in CEA/CTA-2034 ANSI specifications. Likewise listening tests are performed per research that shows mono listening is much more revealing of differences between speakers than stereo or multichannel.
With the offset tweeter, it was not convenient to set that as the tweeter axis. So I made the executive decision to pick a point between the mid-range and tweeter for that.
Yamaha NS-6490 Measurements
Acoustic measurements can be grouped in a way that can be perceptually analyzed to determine how good a speaker is and how it can be used in a room. This so called spinorama shows us just about everything we need to know about the speaker with respect to tonality and some flaws:
View attachment 89601
Man, do we have flaws! Have we measured a speaker with this bad of an on-axis response? I don't remember. From what I have read, the woofer is driven direct and only an electrolytic cap is used for each of mid-range and tweeter drivers. So they all bleed into each other's range causing rising amplitude.
Narrow peaking in the response which shows up in all the upper graphs indicates resonances (something having a life of its own when activated) and we have more of them than I have ever seen. It is like having nearly a dozen little speakers turning on and off all the time.
You can see evidence of resonances just the same in impedance and phase response:
View attachment 89602
Early reflections are flatter but not really flat:
View attachment 89603
Predicted in-room response shows the flaws we have already predicted:
View attachment 89604
Beamwidth is highly variable indicative of no control:
View attachment 89605
Looks like my guess with respect to reference axis was correct:
View attachment 89607
View attachment 89609
Distortion is high as well:
View attachment 89606
Yamaha NS-6490 Listening Tests
Youtubers would go crazy if they tested this speaker: "wow, how detailed!" Well, it is detailed because it has hyper elevated response above a few hundred hertz. It sounds just like it measures. I brought down a number of peaks in the response and that made it somewhat reasonable to listen to. But whether it was resonances or distortion, it would still sound bright.
Power handling was good until it catastrophically was not. A loud static was heard as I pushed up the volume. You get no notice up to that point so I suggest not overamplifying this speaker.
Conclusions
If you were to throw away everything we know about how to produce a proper sounding speaker, and amped up the best marketing and industrial design you could get, you would arrive at the Yamaha NS-6490. In a showroom its bright nature will likely sound good for a a minute or two before you pull out the credit card.
Searching I see some mods online. It may be a fun project to mess with it although you won't get rid of the resonances without a lot of work and expense.
It pains me to give the Yamaha NS-6490 as it really looks good to me. But I just can't recommend it.
------------
As always, questions, comments, recommendations, etc. are welcome.
Harvesting fruits and vegetables at the scale we have was always a pain. That all changed when my wife made this lovely basket that has a leather strap you put on your shoulder:
View attachment 89610
You walk and put items in it. When it fills up, we transfer to a larger container. The above is the last of what was on our Apple Tree. Yesterday there was a dozen or more left. Today half were gone with some animal enjoying them instead of us. Fortunately, we have had so much of them that we don't mind sharing. Then again if it was the darn racoon that ate most of our cherries last year, I am not happy!!!
Having our helper come dig some ditches and clean up around the yard. He makes $15/hour which is twice as much as I make doing these reviews. So please help with
donating what you can using:
https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
)
