Low efficiency vs. high efficiency speakers?

[VinylRob]

><((((º>`·.¸¸.·´¯`·.¸.·´¯`·...¸><((((º>`·.¸¸.·´¯ `· .¸.·´¯`·...¸><((((º>‏

Matching the "right" amp with the "right" speaker is magical, regardless, with that said, my personal favorite tends to be high efficiency speakers and moderate valve amplification. Hi-Ef. just seems to evoke the ambient micro dynamics, dynamics in general, and immediacy and suspend disbelief just long enough to enjoy the experience as that of a real live musical one, better than the other configurations. High Efficiency seems to equate to HiFi. Much old HiFi had it "right" sonically and it appears we have retrogressed to the LoFi point that we need to reinvent the wheel or rediscover the past... just my ears doing some talking.

Happy (HiFi) Listening!

 

[sonix]

From my experience it seems like the lower impedance speakers that require a lot of power, produce the best results. The base is more solid because these speakers can dip low in impedance a powerfull amplifier will bring out the best! Hi efficiency speakers almost always benefit from an additional subwoofer for the low frequencies.

 

[Zeke]

In my experience, the efficiency of the transducer is NOT tied to frequency response. There are many ways to create an efficient, or inefficient, speaker with great frequency response or vice versa.

I'm just saying...

 

[Copa1934]

Based entirely on experience with both types. My Mach One's are very efficient, but at higher volume settings they become harsh. I honestly feel this is not entirely due to design, but in part due to age, however, I have had similar issues with high efficiency. The plus, of course, is driving with lower power systems, for whatever reason, financial, space, whatever.

Lower, not necessarily inefficient, speakers can be driven harder, and I've found don't really deliver the goods till reaching those volumes. They're often smooth, crystal clear, have depth, etc. But if you want to listen at lower volumes you'll also find yourself turning up the bass, using loudness or adding a sub, or even a combination of those.

One thing I have come to appreciate is listening to my Mach One's at lower volumes when it's more about relaxing. They're awesome for HT.

As for the harshness, I attribute that to deterioration of the drivers, that is the mids and tweets. This is one distinction to drivers that are not high end as they will tend to have lower quality parts. This isn't to say bad design, or poor performance, just don't expect the longevity you might from higher end speakers.

I've been doing a head to head with my Mach One's and my JBL L3's. Both have their strengths and each their weaknesses.

As one other person stated, if budget and space allows have at least 2 pair (other than those in an HT system) for different listening requirements.

 

[dnewma04]

In my experience, the efficiency of the transducer is NOT tied to frequency response. There are many ways to create an efficient, or inefficient, speaker with great frequency response or vice versa.

I'm just saying...

There are exceptions, of course, but experience has been quite different. There is a fairly string correlation between flat freq response and low sensitivity. It's the truly special speakers that can pull off both,

 

[bowtie427ss]

Audio pundits throughout history seem to be able to make **** up as they go along, so why can't we do the same?

Looks like that's happened as beginning with the thread title the word "efficiency" is being tossed around generously when the topic seems to be sensitivity. what a great place the world would be if the folks running "audio 101" would teach the unknowing that efficiency and sensitivity are two almost entirely different parameters. ...................... just sayin

 

[dnewma04]

Looks like that's happened as beginning with the thread title the word "efficiency" is being tossed around generously when the topic seems to be sensitivity. what a great place the world would be if the folks running "audio 101" would teach the unknowing that efficiency and sensitivity are two almost entirely different parameters. ...................... just sayin

I think the two terms have been used interchangeably for so long that most people understand what is meant when either is used. Also, I'm really not sure the two terms are that disimilar. In fact, they quite directly correlate with one another. When discussing standard coil in gap motors, high sensitivity drivers have high efficiency, low sensitivity drivers have low efficiency. One is a listed as a percentage, one as an output for a given input. Essentially, they are measuring very similar things.

 

[dnewma04]

From my experience it seems like the lower impedance speakers that require a lot of power, produce the best results. The base is more solid because these speakers can dip low in impedance a powerfull amplifier will bring out the best! Hi efficiency speakers almost always benefit from an additional subwoofer for the low frequencies.

Did you mean lower *sensitivity* speakers rather than lower impedance?

If so, I somewhat agree with a few caveats. If you are a fan of dynamics and power compression free speakers, the route of low sensitivity with a giant amp will probably leave you yearning for more as some of the musical detail will get squashed. Deep bass is easier to get (in reasonable size enclosures) with lower sensitivity drivers. High sensitivity can do it well, but you start needing ridiculously large cabinets to get there. All speakers *always* benefit from additional subwoofers for the low frequencies.

 

[Coytee]

My Mach One's are very efficient, but at higher volume settings they become harsh.

I'm not technical enough to know how to ask this question...

Just like an automobile engine has a torque curve, is it fair to say that their is a "torque curve" for a speaker where the curve represents input voltage verses SPL and identifies a sweet spot for sound reproduction?

If and as you exceed the peak of this curve, you might start to get distortions and some of these negative things??

I know that everyone turns it up every now & then to varying degrees. If I turn my system up so I'm hearing 105 db peaks at my seat, I am probably still on the upswing part of this "bell curve" but, if someone did the same thing with a pair of Cornwalls, Mach Ones, HPM 100's, their speaker would probably be pushing closer (or past) its limits and creating more negative sound issues.

I might add that I've never seen anything labled like what I'm thinking... it's just a thought in the back of my head that again, like an auto engine, there has to be an up-ramp of power going into a speaker where it's going to sound good and then you hit a point where the speaker poops out even though it might absorb more power.

OK...someone come along and put this into techno speak for me

 

[marc mc]

I run both and both sound good. I think like the BR and AS thread is the same argument as this one, and follows what you own or are used to.

In Canada we had lots of speakers come out of the NRC and many were power hogs. The in your face JBL type approach is less popular here. But like anything else it comes down to execusion more than anything else.

I will say that HE Fullrange drivers do certain things with acoustic and percussive music, and rule at low volumes. And a multiamp LE active set up destroys everything I have heard at high volumes. It just never hardens up, it just keeps opening up. So I run both for those reasons.

marc mc

 

[whoaru99]

Based entirely on experience with both types. My Mach One's are very efficient, but at higher volume settings they become harsh. I honestly feel this is not entirely due to design, but in part due to age, however, I have had similar issues with high efficiency. The plus, of course, is driving with lower power systems, for whatever reason, financial, space, whatever.

There are several possibilities for harshness at high volumes. Two prime ones are reaching the speaker limits or nearing the amplifier limits.

One thing that is often misunderstood is flatness of frequency response vs SPL output. A speaker that is (for example) advertised as 30Hz - 20KHz +/-3dB, is typically measured at low power, probably 1 watt. As the power to the speaker is increased it's not unusual for the low end to not be able to keep up with the highs. In other words, say your speaker is 90dB sensitive and you put in 4 watts of power to get about 96dB SPL. The speaker may well put out uniform SPL across the stated frequency +/-3dB, but say you "crank it up" to put 128 watts into the speaker. Now, the volume should be theoretically around 111dB, but the speaker is almost certainly not at +/-3dB anymore across the frequency range.

If you want to see what I'm talking about look at some of the better-documented subwoofer performance curves. As an example, you might see one rated something like 16Hz - 120Hz, +/-3dB, but if you look at the maximum output curves it would not be at all unusual to see that at 30-40Hz the thing can put out 120dB, but at 16-20Hz, maybe only 100dB. Similar type of thing happens with non-subwoofer speakers as well.

 

[bowtie427ss]

One is a listed as a percentage, one as an output for a given input. Essentially, they are measuring very similar things.

One very big difference, distance. Distance is always a factor of sensitivity, it is not a factor of the ratio determining efficiency.

It's just a pet peeve of mine, you won't see a speaker manufacturer worth their salt express efficiency and sensitivity as interchangeable terms.

 

[GordonW]

There are exceptions, of course, but experience has been quite different. There is a fairly string correlation between flat freq response and low sensitivity. It's the truly special speakers that can pull off both,

Well, this can be true.

It's always possible to throw away efficiency, to achieve flat response. In essence, you can just "chop off" the peaks (using notch filters, crossover tricks, etc), to "bring down" everything to the lowest level in the 'unfiltered' response. IMHO, a pretty crappy way to do it. Better to just pick drivers and a crossover topology that doesn't result in a big dip in the response somewhere... so you don't have to go "doctoring" the response as much.

Or, just damp the living hell out of everything (add coatings, and such) in the drivers and cabinet, until the peaks disappear from the drivers themselves... that's another "trap" that many designers seem to fall into, when done to excess. Problem is, you oftentimes damp the "life" out of it (slow the transient response, start to lose low-level information in the same fashion as "gating" the sound might, and such) at the same time...

Regards,
Gordon.

 

[whoaru99]

Yeah, besides, most mfg. don't publish efficiency numbers because they look so bad, as in 0.6% efficient for a 90dB sensitivity speaker. Meaning, of course, that the 100W you put in results in 0.6W of acoustical energy output. The rest, 99.4W, largely goes up in heat, afaik.

 

[dnewma04]

Coytee,

It sounds to me like you are referring to two different situations that could be happening both related to pushing the drivers physical limitations. First, you have the mechanical limitations. When you have smaller speakers trying to produce high SPL at low frequencies, they are going to have to work harder (higher excursion) than larger drivers. (This goes for woofers, tweeters, mids, etc). When you start pushing the physical limitations of a driver (exceeding xmax), distortion will rise dramatically.

The second part could be power compression at play. Standard motors (coil in gap that most of us use) aren't particularly linear as heat increases. For instance, say you take a driver that handles 100w long term and is 85db 1w/1m. Going purely by the book, you'd assume that you are increasing power tenfold, twice, and would gain 20dB by providing that speaker 100w. Therefore, you would be at 105dB 100w/1m. However, that is never the case. You may get 95dB 10/1m but as the heat increases, you may only gain 5dB for that second 10 fold increase in power. Essentially, you can keep doubling power, but the SPL won't increase linearly. When you get to this point, you start to lose the details in the music and it's probably this, as much as anything that attracts people to HE systems. In a typical home setting, a speaker with 95dB+ type sensitivity will rarely ever show any signs of power compression even at high levels. OTOH, a speaker wit 85dB sensitivity trying to keep up will, and in comparison, the sound will fall apart rather nastily.

I've related the story a few times, perhaps even in this thread, but I was an ardent low sensitivity fan and even had it out a couple of times with Brennan in the past. When I finally heard a "good" horn system, I was fairly blown away. It had the clarity of an electrostatic, the dynamics of live music, and a lack of harshness that is easier to acheive with a low sensitivity cone/dome. The frustration I have is that I'm now addicted to dynamic speakers, but only a very small percentage sound good enough to live with. Luckily, I am able to, and enjoy, build speakers that accomplish what i want a speaker to do.

 

[GordonW]

Yeah, besides, most mfg. don't publish efficiency numbers because they look so bad, as in 0.6% efficient for a 90dB sensitivity speaker. Meaning, of course, that the 100W you put in results in 0.6W of acoustical energy output. The rest, 99.4W, largely goes up in heat, afaik.

Yeah, speakers are pretty uniformly s***ty as converters of electrical energy to acoustical energy, from an efficiency standpoint.

To put it in terms of the limit: It would take a speaker, of 112dB/1w into FREE SPACE (i.e, radiating in ALL directions at once), to achieve 100% efficiency. You have to have NO losses... and it also implies that the cabinet would have to be INFINITELY large and the driver MASSLESS to do this...

Someday, someone will figure out a more efficient way to do this. But, until then, we'll live with our "imperfect" technology (no, actually, that should be phrased, "we'll continue to GREATLY ENJOY our "imperfect" technology", I think)...

Regards,
Gordon.

 

[dnewma04]

Well, this can be true.

It's always possible to throw away efficiency, to achieve flat response. In essence, you can just "chop off" the peaks (using notch filters, crossover tricks, etc), to "bring down" everything to the lowest level in the 'unfiltered' response. IMHO, a pretty crappy way to do it. Better to just pick drivers and a crossover topology that doesn't result in a big dip in the response somewhere... so you don't have to go "doctoring" the response as much.

Or, just damp the living hell out of everything (add coatings, and such) in the drivers and cabinet, until the peaks disappear from the drivers themselves... that's another "trap" that many designers seem to fall into, when done to excess. Problem is, you oftentimes damp the "life" out of it (slow the transient response, start to lose low-level information in the same fashion as "gating" the sound might, and such) at the same time...

Regards,
Gordon.

Pretty well what I was getting at. Most of the polypro, sandwich style, and other varieties of well damped materials that are used on various audax, peerless, vifas, etc can be extremely easy to work with because they behave so nicely and don't exhibit the nasty breakup issues that a lot of higher end drivers have that focus on very stiff/light cones. For instance, just about any speaker designer with a little experience can make a speaker using a Peerless CSX midrange and a HDS soft dome tweeter into something with extremely flat frequency response that sounds very good. Give them some Seas Excel and there is a good chance, despite having superior drivers, that they will fail to make something that sounds as good as the Peerless combo. Someone with a lot of experience would be capable of making the Excel components into something that would blow away the peerless.

And I agree about the too much damping thing, it happens in speakers and in peoples homes. I've heard systems in homes where they were going after an anechoic chamber for a room and it sound dull and lifeless, almost eery, and completely unnatural.

 

[MKB1]

Wow, all this speaker design and efficiency type makes my head hurt a bit. I was into designing speakers for my own use for about a decade, until I had an interesting epiphany while borrowing a friend's pair of Klipsch Heresy's.

I was using the Heresy's driven by Mac MC-30's and a very simple 3 stage phono preamp/line stage, and the Heresy's had some real problems. They had a strong overall coloration, the highs were a bit grindy, and did not image at all. I knew it wasn't the amp stage, as this same setup running Audio Concepts Gem's (Focal woofer and Sota dome tweeter IIRC) imaged like crazy.

The epiphany was how exciting the music sounded with the Heresy's. Playing the piano intro on "Year Of The Cat", you could really hear the pianist lean into the chords, and the excitement in the performance came through. I listened to that rig for many hours, one album after another, entranced. It did so much wrong, but it did all the important stuff RIGHT.

I've since moved to single ended tube amps and La Scalas (which image very well and the overall sound is much better, and the excitement of the Heresy is still there). I suspect the magic of horns is in the micro-dynamics; they start the air easier than a larger less well coupled non horn loaded driver. Also, since you can use smaller amps, the signal chain gets much simpler. I strongly suspect you lose information with complicated electronics, the simpler the amplification string the better.

For sure the Klipsch's are extremely unforgiving of amps, but Klipsch's are warm and natural sounding with the right electronics. The MC-30's were very good sounding, but a pair of single ended 211A amps was an even greater step up in warmth and immediacy. You start hearing stuff like every instrument has its own harmonic space, and instruments in the same tonal range can be easily distinguished. IME this information is lost in many of the lower efficiency speakers I've heard.

But in the end, it doesn't matter what you use if it rocks your world and keeps your butt in the seat for hours.

 

[Pyrrho]

Based entirely on experience with both types. My Mach One's are very efficient, but at higher volume settings they become harsh. I honestly feel this is not entirely due to design, but in part due to age, however, I have had similar issues with high efficiency. ...

I doubt it is due to age. I owned a pair of Optimus T-200 speakers in the early 1980's (which were the model above the Mach One's), and as the volume went up, they gradually seemed to distort more and more. You can see them on page 24 of the 1980 catalog (you can also see them in other year's catalogs, as they were the top of the line from Radio Shack for several years):

http://www.radioshackcatalogs.com/catalogs/1980/

It was not due to them being "old", and, in my opinion, they sounded better than the Mach One's (which they should, since they cost more), but could not put out as much bass.

I replaced them with Heybrook HB-2 speakers (unfortunately, Heybrook reused that model number for a different speaker later on, which may lead to confusion for anyone trying to locate the particular model), which are a small two-way speaker with a 6 1/2" woofer, which retailed for about the same price, and they did not have that characteristic at all. They sounded great until one turned up the volume enough to cause the woofer to "bottom out", and then they sounded worse. But since that was louder than I cared to listen to them, they were much better for me. Surprisingly enough, the bass output was comparable to those Optimus T-200 speakers. With speaker design, there is something to be said for putting the money into better drivers than into more of them in a larger cabinet.

Basically, there is a tendency for any speaker to distort more the louder it plays. But how audible that extra distortion is varies greatly from one speaker to the next, just as other characteristics vary greatly from one speaker to the next.

 

[Pyrrho]

Regarding the issue of the sensitivity of speakers, as has already been mentioned, speaker design is a matter of tradeoffs, with low sensitivity not being a goal, but something that is sometimes accepted in exchange for something else.

The best sounding speakers I have ever owned are Apogee Stage speakers, which you can read about at:

http://www.apogeespeakers.com/stage.htm

They are low impedance, low sensitivity speakers that require a high powered amplifier to make them play loud. They are also bothersome in other respects, as they seem more picky about their placement than any other speaker I have ever had (there is good advice in the manual for how to get the most out of them), though they sound good even in less than ideal positions. They sound absolutely fabulous when setup right and one sits in the right position. But Apogee traded away quite a bit to achieve their sound. In my case, I am happy with the tradeoffs, but not everyone would be.

In all cases, it is a question of what qualities matter most to one, and what one can afford and has room for. There is no such thing as a perfect speaker, or anything very close to it.