That the idea that dynamic range is improved or noise floor is changed due to speaker efficiency alone is simply not true?
@lonemountain In a word, No. The physics of how voice coils work is the problem.
While there may be examples that support this idea, there are far too many exceptions to make this speaker efficiency issue a universal need?
There really aren't that many exceptions! ESLs are the only speaker that might not be all that efficient but do not suffer thermal compression because they do not use voice coils.
There are attempts to get around the thermal compression problem with lower efficiency speakers, such as vented pole pieces and the like. The incentive is high because lower efficiency speakers are a lot cheaper to make.
For me, I prefer no negative feedback and appreciate the delicacy, dynamics, tone and texture that many find in single ended amplification and the speakers that showcase that.
@ghasley Many amplifiers have troubles with how their feedback is applied (I can explain what the issues are if you're interested). If you get to hear an amp were its done properly, you might have occasion to rethink this.
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Nothing sterile, tonally lean, mechanical or bright sounding about the Brit, I can tell you that, or whatever you’re implying about high power amps sonics.
@phusis The issue is that most amps made using feedback, which includes high power solid state amps, is that the output transistors usually limit the design's Gain Bandwidth Product, resulting in a loss of feedback at high frequencies (depending on how much loop gain is asked of the design). The result is distortion rising with frequency, which seems to be more audible than the actual distortion spectra created by the amp. Class D offers a way around this problem.
Another generality, indeed this one is a myth that has gone on forever.
The issue here is that a lot of higher efficiency speakers are designed for amps with a higher output impedance. Such amps try to make constant power rather than constant voltage; this is not a myth. The Power Paradigm is what was around before MacIntosh and EV started promoting higher feedback in the mid 1950s so as to cause their amps to behave as a Voltage source, allowing plug and play. You might want to read this article for more information.
Flea watt SET tubes produce a lousy loose wet noodle bass, sounds like a sloppy fart. It's not a myth.
@deep_333 You might want to read the article at the link above as well. This is not a myth; its a matter of whether the speaker designer meant for the speaker to be driven by an amp of high output impedance. If so, the bass will not be as described (although SETs in general do tend to have less impact on account of phase shift above their cutoff frequency, which tends to be quite high due to their output transformers).
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Example: even its inherent importance of speaker impedance phase no one name it and this is something to take care when we are choosing an amp
@rauliruegas Actually this has been brought up in this thread.
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If a speaker requires an amp/ arc welder up front to drive it, then IMO, there is a problem with the speaker design. YMMV.
Exactly! Such speakers border on criminal as there simply aren't amps that sound like music that can drive them nor would they be all that musical due to thermal compression.
I look at it this way- if you can't drive it well with 100 Watts (in most rooms), its a problem. That is because the ear hears sound pressure on a logarithmic scale. So to get twice as loud (perceptually) that you can get with 100 Watt, you need 10x more- and 1000 Watt amps that sound like music don't seem to exist although class D is getting close with amps that can make 600 Watts or so.
The problem (again) is getting enough Gain Bandwidth Product in the design such that it can support the gain of the amp along with the feedback it has (together, known as 'loop gain'). If not, and this applies to almost all amplifiers ever made prior to about 2000 or so, you get distortion rising with frequency with its attendant unpleasantness- this is a good portion of the reason feedback has gotten a bad rap in high end audio.
Its not feedback's fault so much as poor execution of feedback.
Plus a 1000 Watt amp would not be able to make up for the thermal compression that would be present- as I mentioned before, as you try to turn it up to get around the problem, it just gets worse.
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I suggest since you are such a big fan of the Parasound JC1+'s sound that you go out and immediately buy a pair, if you haven't already...That's what I am talking about...;0)
@daveyf :)
Distortion vs frequency is a better measure of how musical the amp might be. It must not rise in the audio band else higher ordered harmonics can become more audible than THD values (usually measured at a pretty low frequency) would suggest. You can see this is a problem with the JC1. This is caused by a low Gain Bandwidth Product value, where the feedback ceases to be supported at a certain frequency and so decreases, initially at 6dB/octave. Distortion thus rises on a complementary curve. This is a very important reason why do many solid state amps of the past have sounded bright and harsh- its literally what has kept tubes in business the last 6 decades.
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The physics of the speaker is a balancing act: if you want more efficiency you give up other advantages. Im not saying this is wrong, it’s simply a choice. A moderate efficiency speaker (86dB 1w/1m) is not a mistake either as it is just a different choice that enables other performance features that high efficiency cannot offer. You cannot have it all.
@lonemountain Unless you can. I have a set of Classic Audio Loudspeakers (model T-3.3) which are some of the most revealing speakers I've heard, even compared to the best ESLs. They are flat to 20Hz, are 98dB, field coil powered and 16 Ohms. So fast, revealing, full bandwidth and actually work quite nicely in a smaller room since you can back them up against the wall behind them without making them boomy or losing any sound stage palpability. Put another way I don't know of a speaker at any price that works better, although its probably out there.
They are not cheap; IMO your comment would be more accurate if price were part of the equation.
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Problem is that they also require a very large ss amp upstream to drive them. Something that can push a lot of current, which pretty much rules out most low-mid ( maybe even high) powered tube amps. When I mentioned this to the person doing the demo, i was basically belittled, as he felt that the efficiency of a speaker is pretty much irrelevant ( well he would, as he is trying to sell these speakers). The speaker line is fairly well known to drop down to a very low impedance level in the bass regions. This requires an amp that is going to be $$$, as it has to not be bothered by the lowest impedances.
Low impedance and low efficiency is a bad combination if you want the best out of your amplifier, regardless of the amplifier type.
@ditusa has put his finger on a serious problem with lower efficiency speakers, one that isn't overcome by higher amplifier power, in fact makes it worse.
But you also have the problem of distortion from the amp. With any amplifier, the harder it has to work the more distortion it will make. So 4 Ohm distortion is always going to be higher than 8 Ohm distortion. You might think that small increase isn't audible but that would be ignoring how the ear perceives sound and in particular, tone color and sound pressure.
Sound pressure is perceived through the higher ordered harmonics, If you increase them by even tiny amounts its audible as greater loudness (BTW this is easy to demonstrate through simple test equipment).
Distortion modifies the tone color of instruments by adding harmonics. IOW the ear perceives harmonics as a tonality. So adding even a slight amount of distortion will color the sound and very likely in the direction of 'harsher' and 'brighter'.
Put yet another way, if a speaker could be made to be 8 Ohms instead of 4 without changing anything else, the perception would be that the speaker became smoother and more detailed simply because any amplifier driving it would have less distortion.
So efficiency and impedance are both important!!
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Btw, I remember listened 4-5 times in the past the original Wilson Watt and this is a fantastic true monitor not high efficiency as a horn but measured 91db and this Watt has a problem for any amplifier ( tubes forbidden with ) at 1khz its impedance surve measures 1ohm and near 2khz 0.32 ohm . IN those times the preffered amps for it were Krell and Spectral.
This is mostly incorrect.
At the time this speaker was made, the national sales manager of Wilson was using Atma-Sphere OTLs in his home system. The Watt was an easy load for any tube amp (David designed his speakers using ARC amps and often showed with them; my first exposure to Wilson was at the ARC factory).
That 1 (or 2) Ohm load was at about 2KHz where there wasn't a lot of energy. The tweeter had a resonance problem and so there was a 2KHz trap that presented the amp with a low impedance, thus knocking out the resonance pretty well. This worked great with tube amps! Not so much solid state, as solid state amps would often make more power into a lower impedance rather than less.
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You’re referring to a boutique element of high efficiency drivers that aren’t representative of this segment. Low eff. drivers have their expensive iterations as well, and when you count in the typically larger size of high eff. drivers, bigger voice coils and more magnet material, not least from the more widely accessible pro sector, their pricing compared to low eff. "hi-fi" dittos is actually very fair. Most of these very expensive high eff. drivers are vintage designs of limited production, btw., and it’s not that the production tolerances here are somehow magically "tighter" to reflect and account for the higher pricing.
Tidbit: just going by specs the EV woofers of my main speakers share the 97dB and 22Hz Fs TAD numbers of yours (Fs 21Hz, "broken in"), and I’m guessing they’d have retailed for about 1/10 of $4,000.
@phusis I think the power handling might also be part of the difference in price. My speakers also use a set of field coil powered 15" units, hand made by Classic Audio Loudspeakers that seem well north of the $4k of the 1602s.
Being few of these designs are vintage, or so I suspect, it hardly reflects a strict need for a particular driver-amp type adherence. My guess is many like for horn-based designs to be "toned down" a bit (tubes generally would seem to do just that) so to likely please a former habitual exposition to less dynamically/transiently capable direct radiating and lower efficiency designs.
Horns were used in the old days because tube amplifier power has always been expensive so you had to get the most out of the power you had. The use of controls on these older speakers clearly places them in the Power Paradigm.
I merely implied that context is paramount, and moreover suggested that what you advocate design-wise could as well end up being refuted (i.e.: the ears being the most important and last "judge" of things), not necessarily to say some people wouldn’t like the sound of your amps, but that they may prefer a speaker-amp combo that goes contrary to what you recommend :)
FWIW I'm one of the few that see a direct line between what we measure and what we hear. I'm of the opinion that the implications of what the measurements are telling us are not well understood so people still trot out the old saw of our ears being able to hear things we can't measure. So I'm of the same camp as Daniel vonRecklinghausen.
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@lonemountain You are inferring something I did not say with this statement:
The idea that lower efficiency is always done as a cost saving excercise is clearly not true.
I don't need to repeat myself here. But it may interest you to know that high efficiency drivers, in particular woofers can be 10x more expensive than drivers of similar bandwidth and power handling that are not efficient. As an example the TAD 1602s (15", 97dB, Fs 22Hz) are typically $4000.00 each. Put a field coil into the mix and the driver gets even more expensive.
What I said when you quoted me is correct.
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Dependency and "seems to be" - as a technical observation I don't see how it holds an absolute correlation with regard the sonic outcome of SS amps in each and every case and high efficiency speaker combination, and to which degree?
@phusis Rising distortion with frequency can cause an amp to sound harsh and bright. A typical example would be if the distortion begins to rise at 1KHz which is quite common; the 7th harmonic is at the upper end of the Fletcher Munson curve, so due to the extra sensitivity of the ear at this frequency, the fact that the ear uses higher orders to sense sound pressure, and the emphasis added by the rise in distortion, you get brightness and harshness. As you know, harmonics are what the ear uses to distinguish the difference between a trumpet and a clarinet; if harmonics are added with emphasis in this manner it causes instruments to sound harsher and brighter. The degree to which this occurs has nothing to do with the speaker and everything to do with at what frequency the distortion begins to rise (the point where the loop gain exceeds the GBP).
Wouldn't the design of high efficiency drivers reflect more than a limited range of amp designs of their day?
For vintage speakers, no. For speakers made since the Voltage rules were adapted, yes. But you'll find, if you look, that most producers of higher efficiency speakers tend to use tube amps. At any rate the kind of amp used has nothing to do with the phenomena of thermal compression. My speakers were designed for amps of higher output impedance, but owing to level controls for the mids and highs (which are there even on vintage designs to allow the speaker to be adjusted to the Voltage response of the amplifier) they work fine with my class D amps.
Interesting, and informative article. Offering technical insight it must also come to acknowledge that what is advocated here can as well be counteracted perceptively, if nothing else by the myriad intricacies of a context:
What are you trying say here? If we didn't have ears, its unlikely that we would be playing around with audio equipment :)
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