[Bartstar]

In my days from long ago, when I was in the purchasing mode for stereo speakers, I'd take a select set of CDs with me as I went from one store to another. I would listen to the same music selections when demoing speakers at different stores in hopes of have some chance of a fair comparison (assuming I could remember what I heard from one store to another). Now I'm getting ready to evaluate speakers for my first Home Theater. I would assume that a similar method should be used. I would also assume that when demoing HT speakers, DVD's would be more appropriate source material then music. So, what type of demoing source material do you like to use? I'm looking for suggestions.


Thanks

Bart

 

[John Desmond]

Me, I'd probably still stick mostly with music that I'm familiar with. The music is more important to me than the effects. Besides, I've found that if a system will play music well, it will also do the special effects well. I think I'd start with comparing left-right speakers in simple stereo mode. Seems much easier than trying to compare whole, multi-channel systems. Find the mains you want and build around that. I'd be looking for a system with a center channel that was designed very much like the left-right. Just a couple of ideas.

 

[Drew Eckhardt]

1. Skip the DVDs. If a speaker does justice to loud, complex music (symphonic) it'll work great for home theater and not be fatiguing (a forward sounding speaker is more impressive when first listened to). The converse is not true - the exagerations of some "home theater" speakers butcher music and become less pleasant after extended listening sessions. Even in a pure film environment, music is very important because the theatrical score plays a big role in emotional impact.


2. Use a wide variety of music. Different recordings should be different - if they all play back with the same character, the speaker is getting in the way by imposing its coloration on them.


3. Reference _live_ sound, NOT your current system. You get used to a certain set of inaccuracies, so different sound is wrong in comparison.


4. Nothing in the sound should stand out. The speakers shouldn't sound detailed (this may be excessive treble/upper midrange); although if you listen carefully inner detail should be present. You shouldn't immediately notice the bass - although the double and electric bass will be articulate and musical.

 

[WanMan]

1.) Determine what function the speakers will have.

2.) Determine what budget you cannot afford to break.

3a.) For music, bring music to the showroom, close eyes, and listen.

3b.) For movies, bring DVD's to showroom and keep eyes open and continue to listen.

4.) Determine which speakers that sound the best to YOUR ears that meet the above criteria.


Things to keep in mind that a speaker rated by everyone else as 'the best' may sound crappy to you, and recognizing that only you can hear the way you hear because they are your ears. Of course, being human means your ears may not be the best they ever were, and will probably degrade over time.

 

[TheMadMilkman]

Take Notes! I don't know why nobody seems to do this. Write down what you liked about the speakers, what you didn't like, how certain tracks sounded... It will give you a better reference than just trying to remember how the sound was on another set of speakers.

 

[blw]

I found that I needed to turn OFF the video display whilst evaluating speakers, at least at first. For me, the video far too distracting while doing something like evaluating speakers. Once I'd narrowed it down to the last two (or maybe three) choices, I went back and turned the video back on, to make sure that the sound matched the video. Perhaps this last step wasn't necessary; both of my choices matched.


Incidently, I agree about the taking notes bit. I have a reputation for remembering everything, yet I'm amazed at what I find in my notes that I've forgotten...

 

[hometheaterguy]

My dog is my speaker evaluator.

 

[Swampfox]

Quote:

Originally posted by hometheaterguy My dog is my speaker evaluator.

My adult male dog is very discriminating and seldom gets fooled by recorded sounds. Sometimes he is an interesting test. My ***** puppy on the other hand gets fooled easily, but I'm guessing she'll grow out of it. Dogs have amazing ears.

 

[hometheaterguy]

LoL! Got 20KHz?

 

[Bartstar]

Thanks everyone. Some very good advice. It seems that my understanding of how to evaluate speakers from 20 years ago hasn't changed due to the new application to which they shall be applied. I must admit, I hadn't though of bringing my dog. If I could only get my boxer to tell me what he likes best, I'd take him along for the evaluations. Alas, I don't think he's up to the job as of yet.

 

[fasteddielv]

I will add that an understanding dealer is also important. Will they let you take home and listen. Returning if not happy. Just as speakers have different sound, so do rooms (which is the biggest component you have). In effect you are putting a speaker inside a speaker. So how they sound at the store may be much different than at home.

 

[Chronosphere]

Quote:

Originally posted by Drew Eckhardt 1. Skip the DVDs. If a speaker does justice to loud, complex music (symphonic) it'll work great for home theater and not be fatiguing (a forward sounding speaker is more impressive when first listened to). The converse is not true - the exagerations of some "home theater" speakers butcher music and become less pleasant after extended listening sessions. Even in a pure film environment, music is very important because the theatrical score plays a big role in emotional impact. 2. Use a wide variety of music. Different recordings should be different - if they all play back with the same character, the speaker is getting in the way by imposing its coloration on them. 3. Reference _live_ sound, NOT your current system. You get used to a certain set of inaccuracies, so different sound is wrong in comparison. 4. Nothing in the sound should stand out. The speakers shouldn't sound detailed (this may be excessive treble/upper midrange); although if you listen carefully inner detail should be present. You shouldn't immediately notice the bass - although the double and electric bass will be articulate and musical.

Good advice here. I just want to comment that if the reference is live sound (I assume that in the case of listening to symphonic music this means an entire orchestra in a concert hall) then "detailed" speakers are revealing more of the truth than laid back speakers. In fact I feel that people normally choose laid back, mellow speakers when their main reference to decide what is "good sound" and what is not is that they are comparing what they are listening to the performance of other speakers, laid back speakers of course.


Just a piano and a violin can make an incredible amount of noise. Nothing soft or laid back here... except if they are playing pianissimo.

 

[thomaspf]

There is a notable roll-off of high frequencies with distance. Many recordings are close miked which creates an unrealistic representation of what a performance sounds from a normal listening position in the audience.


This combined with the fact that many speakers in the the North American market are voiced to exagerate the high frequency output makes them hard to endure.


When you look up Stereophile measurements which independent on their overall merit have the benefit of comparing equipment with equal and standard test conditions you will find that raising higher frequencies by 3-6db is considered flat these days....

http://www.stereophile.com/showarchives.cgi?663:4
http://www.stereophile.com/showarchives.cgi?302:7


There is a difference between detailed and just equalizing the frequency curve to output more high frequency energy.


Interestingly enough the sense of being at a live venue seems to be much more impacted by the midrange which is nicely demonstrated if you compare a Harbeth Radial with a Spendor Polypropylene driver. A lot of people would consider either speaker as being laid back but personally I believe the Harbeth has the edge on creating a sense of being at a live event.


Reproduction of human voice is essential for Home Theaters unless you only want to listen to concert DVDs. The dog test is actually a really good one. If you can fool your dog with a set of speakers, the sense of recreating a realisitic experience is pretty high.


There are of course speakers that label themselves laid back which are simply dull.


Cheers


Thomas

 

[hometheaterguy]

Got Kevlar?

 

[Brucer]

Having an understanding of some of the physics behind the sound for various instruments and vocals can help to distinguish varying traits of different speakers reproduction in a side by side comparison. To do this, one must become familiar with specifics of certain passages of various recordings, then compare the same with the auditioned speakers.


Here is just one example.


Below is a link to a great site that explains "Formants" (among many other things). Understanding how this relates to certain instruments (woodwinds) and vocals can help one to determine which speakers are trying to "over-define" certain narrow or limited range(s) of frequencies. Formant frequencies are fairly constant, regardless of what the fundamental frequency note is.


So, if a speakers voicing has been tuned to exaggerate (for example) 3 to 4khz to portray more 'detail', a recording with some clarinet passages might be a good way to verify that is the case. Overall, single instruments should not stand out as sounding better (or worse) than other instruments.


IMO, to often is the case 'nowadays', that people want to HEAR 'bright' (calling it 'detailed', 'articulate', or even 'accurate'), but SEE 'Flat' on paper.


http://hyperphysics.phy-astr.gsu.edu...rchins.html#c2

 

[thomaspf]

From what I understand, Kevlar while light and rigid is not necessarily a good material for speaker cones despite many manufacturers liking for it.


Independent of the excitement by the coil every cone is a resonator by itself and it takes a great amount of care and experimentation to dampen these resonances. Kevlar might shift those to higher frequencies but often adds a certain snappy coloration.


Cheers


Thomas


P.S. I agree with Brucer's statement.

 

[hometheaterguy]

I have heard the same of Kevlar. In spite of this B&W continues to exalt the superiority of Kevlar.

 

[Brucer]

Over-generalizing about a material can lead to untruths. Dick explains some of the points of interest here:

http://groups.google.com/groups?q=ri...enn.edu&rnum=1


"Kevlar (polayamide fiber) was first used in the midrange of the B&W DM-6 way back in 1975 or so. THe advantage to Kevlar is it has a very high tensile strength, it's hard to stretch, for its density. Thus very light supporting structures with high capacity can be manufactured using kevlar.


Now, by itself, a woven net of kevlar is pretty useless as a cone material or a bullet-proof vest or as a helmet. Look how a bullet proof vest is constructed: it is made of layers of kevlar interleaved with a light but fairly stiff matrix whose primary job is to keep two alternate layers of kevlar a constant distance apart.


Along comes a bullet and hits the middle of the vest perpendicularly. What's going to happen? Well, the forward momentum of the bullet is going to attempt to push the kevlar in-wards. But the layers separating the kevlar are essentially going to transform the bending component, which the kevlar is not very good at resisting, into a stretching component, against which it is quit effective. This conversion distributes the initial forward momentum into an attempt to shrink the linear dimension of the vest, which the kevlar is going to do its damnedest to resist. Now what happens if that the effect is to tighten the vest around the torso, distributing the rather large amount of kinetic energy (1/2 mv^2) over a much larger area. It's still gonna hurt like a sonuvabitch, and you might even break a rib or two, but that's better thah the alternative where that same energy is concentrated in a fraction of a square centimeter.

In a loudspeaker, where the cone has decided it's time to go into a breakup mode, the motion is a bending motion, one which kevlar is not very good at resisting. There are two ways of combating this.

The first is the method used by people such as Eton, where the drivers are actually two layers of kevlar separated by a light matrix material. Here, bending motions are turned into stretching components, and the Kevlar resists that, effectively increasing the stiffness of the cone rather substantially with but a slight weight penalty. The problem often associate with these drivers is that while they are generally very wide band, the internal losses are low, and once they do start to break up (albeit at higher frequencies), they do so with a vengence. I have seen kevlar drivers costing hundreds of dollars with high frequency responses that were indeed extended, but there exists $0.75 public address speakers with markedly smoother response.

The second way is to use the kevlar as a carrier for a high-loss material, in the way B&W did in the DM-6 and DM-7. Here, they weren't going for the ultimate in bandwidth, but the stability and reproducibility and consistency of the material was used to its advantage, and the resonances were controlled because of the high-loss dopant applied. They did not have the impressive wide-band response of later kevlar drivers, they were arguably smoother and better controlled. And there are some resonances that force a stretching mode, and the kevlar was good at controlling that.



--

| Dick Pierce |"


Edit: Corrected for spelling errors.

 

[hometheaterguy]

Thanks Bruce, maybe this is why Lucus likes the 802s in the Ranch.

 

[thomaspf]

Very nice summary.


Yes, it takes great care to turn Kevlar into a decent material for cones. Calculating the material properties of sandwiched structures and manufacturing them cost effective at reproducable quality is dramatically more complex than optimizing a homogenous single layer of the same material.


It reminds me of the Spendor Bextrene cones that were hand painted with glue as the lossy layer. Then they spend time matching pairs of them that were similar in frequency response. Kevlar cones is the same idea applied to space age materials....


Cheers


Thomas