Do high efficiency loudspeakers harm sound? 

Paul’s a very knowledgeable, no nonsense sort of guy. Be great to talk to him.

Regarding high efficiency speakers, one thing to consider is that lower efficiency speakers generate lower relative amounts of harmonic distortion. Speakers that are hugely efficient tend to generate sounds other than the incoming signal alone. We want speakers with very stiff, rigid, well damped cones that operate only in a pure pistonic manner. Part of making a high efficiency speaker is to reduce the moving mass of the cone which means compromising the stiffness, damping, and rigidity of it, thus allowing it to generate higher harmonic distortion products.

Fly by wire in aircraft or electronic/digital vs “old school” potentiometer volume control aside, Paul hit the nail on the head by saying system matching is a requisite for an ideal marriage and effective use of a HiFi amp and speaker. A 250 watt amp will drive virtually any speaker, high efficiency or otherwise. It may not, however, be the best match for high efficiency speakers as Paul aptly stated. Know your system and what you want to achieve when matching individual HiFi components is key. Caveat emptor.

Great question and brilliant answer Paul, I truly loved the older Yamaha amps and stereo receivers

4:25 The Boeing 747 and 737 still use cables to actuate the control surfaces. They are boosted by hydraulics, not unlike power steering in a car (although power steering is becoming more and more powered by electric motors). Fly By Wire is a somewhat recent development in the grand scheme of things.

I dunno Paul. A pair of Klipsch Forte IIIs with your stellar stack and a rel sub is pretty amazing. The 600m coupled to some dense stands run by a sprout would be a nice little setup.

Great question! Many sensitive speaker's are often driven by low output valve amps. Most of those l guess still use potts even if there modern

We had VCA'S in the early 80's Some high end mixing consoles had them even earlier Vca is voltage controlled amplifier

Potentiometers and mechanical rotary switches are still often used in analogue/passive audio equipment as far as I know. For example: I have an SPL Phonitor 2, which utilizes a motorized potentiometer to control the volume by hand and remote. However, most digital audio equipment use quadrature rotary switches, which are indeed not controlling audio levels directly, but by means of graycode or something similar. These signals like graycode are recorded by a microcontroller. This microcontroller controls the amplification circuit accordingly to the recorded codes. It just depends on the type of audio equipment: analogue or digital. So it has nothing to do with equipment being 'outdated' or something.

Paul McGowan! I am in trouble with other RU-vidrs for not being in touch because I have been watching your videos instead!

I enjoy listening to classical music, particularly symphonic music. The "voice" or timbre of the symphony is predominantly from the horn section. This is because horns project the sound into the room much more efficiently than any other instrument class. They also radiate in frequency ranges to which the human ear is more sensitive. Another benefit of horn transducers is their ability to play at very low volume levels and still allow you to pick out the separate voices in the group without disturbing the neighbors or other member of your family. Bell Labs determined horns to be the most intelligible means of sound propagation way back in the 1920s. Critics of horn-loaded speakers say they sound "honky", when they are referring to listening at too close a proximity to a speaker designed for a very large listening room or hall. Yes. When your face is practically inside a big diffraction horn you will get spurious reflective sounds and echoic beaming. The engineer who designed the speaker never intended the audience to be seated on the stage with performers, in effect. The remedy, if you have giant theater speakers or other highly-efficient equipment in a small room is to turn down the volume or sit farther away. Each speaker class is designed for a certain optimal listening distance. Folks who throw big parties in large living areas or even out of doors use high-efficient horn-driven equipment most often. So do rock concerts. An added benefit is distortion rises as gain goes up. So the lowest gain commensurate with adequate sound pressure levels reduces distortion. I recreate the sound of a musical group in my listening room at concert sound pressure levels (98 dB @3') with a 20-watt per channel amp running at 1 watt! Friends, most of whom are hardly audiophiles, say my system sounds more realistic than anything they've heard. Or maybe it's the free drinks and snacks!

Volume control can be done on an analog signal or digital signal. Low volume can also cause harm when using digital signal volume control. For example, if you run a volume setting of -36dB of a 16 bit digital signal, you actually reduce the bit resolution to 10 bits (16-36/6) and only 60dB (96-36) dynamic range. Nowadays digital gear using 24 bits through a digital volume control can greatly help reducing this issue.

I have this exact problem. Gonna put bigger resistors in the amplifier input section to tame it. I can barely touch my volume the gain from the 2.3v outputs on modern gear is ridiculous.

Back when I was a kid........... I still miss those old Zenith all in one counsel TVs with record and 8 track. Those things rocked. From a fairy step to a dinosaur roar on sound scale.

The only thing on the market now, that I know of that uses a pot for Volume is an Electric Guitar, and some people get so touchy about the volume pot taking away there tone they solder on something call a treble bleed or as you know it a high pass filter right on to the pot.

Hate to be pedant, but the almost 50 year old 747 uses all hydraulic control systems. The first fly by wire Boeing passenger jet was the 777 introduced some 25 years later.

i finally figured out why this guy likes sub-woofers, he likes high-efficiency speakers....

Interesting topic, anyway here's my input- Efficient speakers tend to have thinner cones for lower moving mass, and can have cone distortions as a result. Larger boxes are more efficient, though leave the driver under damped, more distortion Though arraying speakers also increases efficiency, and as long as it can mimic a point source can sound better and be more efficient As long as horns are crossed over properly they shouldn't decrease in sound quality, as they act similar to bandpasses, they must be constructed well though And then there's portable bluetooth audio- drains power like crazy, sounds like crap I believe this stems from valve amps sounding best, though being inefficient, and class D being the opposite, so the idea of a trade-off

Back when I was a teenager, and we would get into these car stereo wars. I was poor, but knew a thing or two. So these rich kids are getting these 500w speaker systems and 500w amplifiers to drive them, while I stuck with a little 140w amp... but I bought the highest efficiency home speakers I could afford. So while I'm pumping out 101db @1w, they're having to pump 20w to match because their high powered speakers totally suck at efficiency. You can see where this is heading. At 114db, they're already struggling to keep up. At 118db, their amp is clipping, overheating, and sounds terrible, while mine is still only pumping out 51w. So I turn it up just a little bit more and beat them. I never told them how I did it, just sent them off to blow another $1000.

I use a Music First preamp (transformer coupled), Fi X and Volti modded Klipschorn speakers...and I love it! My future purchase will be a PS Audio AC power interface.

My stereo speakers are pretty high efficiency, but living in a condo unit, I never crank them. I have an old Sony receiver that is 100 watts per channel, but easily drives the speakers, and gives a good "emersion" effect with the sound. For what I use it for, it sounds really good. There are better speakers and amps out there, but I don't need them for my stereo right now. It's very different than my 100 watt guitar amp on a 4x12 half stack, or my 800 watt bass amp with a vented 4x10 with tweeter an top of a vented 1x15 with a tweeter, but I use them for very different things.When I play live, I need to be heard, but on my home stereo, I almost never turn it up loud. I do most of my critical listening with headphones or on a couple of JBL LSR308 near-field. I favor the headphones. I practice bass and guitar with a Sans Amp and a pedal board through headphones.

Paul decided to film in a Costco for this one

My upside down 15 in pa drivers in less two cubic foot boxes, at 101db efficiency rating, plays at levels all day long that make you want to shake your head afterwards. Right around 50wpc+, the speakers have a force to be recognized. So yes, efficient speakers are very nice.

somewhat do , beacuse you have to use some L=pad or different resistor networks to put them in order.

Ryad where do you buy LPs? Vai Kothari? Ganer Dali?

one point you did not mention is the trade off between efficiency and bass response for a given cabinet size. And yes Airbus came up with fly by wire, the 747 is based on the technology of it’s time and is mechanical & hydraulic, still the explanation was a good one even though the choice of airplane was not the right choice 😀

Yes and no. Efficiency is just part of the properties a speaker might have. And then again,part of the answer depends on what you consider high efficiency. PA speakers are built to fill large ares with sound and sound quality if most often traded for efficiency. While some highly accurate speakers are extremely inefficient. But if you choose the right drivers, and built the right cabinet for them you can get pretty efficient speakers that sound very good.

I trust all that you say I am an audiophile since I was born I'm waiting to purchase those servo speakers truly interested from Toronto I text ****twice I had custom built speakers made by people who know Canada make great gear but I luv my USA audio

As long as the resistance value of the pot is double the resistor on the signal path right after it, and half the value of resistance to ground/neutral, with pre/power amps properly impedance matched, you SHOULD, in a perfect world, have a volume knob that is same volume as source at noon, and no tonal balance shifts either. If your design calls for an input capacitor between the volume knob and following resistor, as with most class A preamps, it can be very difficult to avoid that high end roll off because your essentially creating a filter that slowly boosts the low end response as you turn the volume knob down. Its very subtle, but still there, even when done right. As you turn the volume down you are raising the impedance of the incoming signal, allowing the following cap value to pass more frequencies closer to DC then otherwise. Many modern designs have been able to remove the input capacitor handling this issue effectively though, and On class A tube preamps, i dont notice any high end roll off though turning volume down. This is probably due to a tubes higher impedance when driving low frequencies id assume. It's a case of an imperfection in a component solving an issue created elsewhere, and a big part of why when i play with a preamp, it's a class A tube preamp, perfectly imperfect. If your preamp doesnt quite drive your power amp hard enough, you can actually end up with the opposite problem when turning down the volume, a LOSS of bass lol. If the impedance mismatch is bad enough, youll straight up create a high pass filter that completely destroys your low end response no matter how hard you push the preamp.

I think this is a difficult issue. The low output phono cartridges sound better in most applications and the reason is something most audio reviewers seem to NOT discuss much - WHY ? The wound coil in speakers plays a role in the efficiency of the speaker, more turns translates to bigger fields in play with the magnets. Using the formula for impedance Z=2piFL tells us that the inductance of the coil in efficient speakers would typically be higher. That also translates to rise time differences and residual field issues - again why do simple low output cartridges sound better ?

High efficiency speakers can hurt the bass extension. EX: the L100 re-release is massive, by struggles to produce as much bass as speakers 1/3 the size. Also: power is cheap and mostly irrelevent. For dynamic peaks we have amplifiers that can deliver thousands of watch with high power capacitors. If you need high sensitivity, you're probably into lower powered vacuum tubes in which case you probably don't care about fidelity or extension anyway, so don't worry about it.

"Horns are bad" Like Klipsch horn tweeters and midranges on the Fortelll? Like tapped horn cabinets for subwoofers? Waveguides are a bad thing? Sorry I got confused at that part.

Hey Paul! I always wanted to ask you this: Do potmeters have the same effect in class D amps as well? I'm not in audio engineering so pardon me if I say something absurd. If I understand correctly in a class A amp you basically put a resistor in the line to controll the voltage. However in a class D amp the whole output tied to the volume anyway. So does a potmeter have the same effect? I have a class D headphone amp with a pot, also a 90's Marantz with a pot, so that's why I'm interested.

Hey Paul - I guess you are not a big fan of vintage Klipsch speakers then... I have a "mostly" Klipsch speaker system with a pair of Cornwall's (1978) as my main front left and right speakers in a Home Theatre setup. As you mention, they have huge dynamic range, with an airy "New England" sound. I am currently driving them with a Denon AVR-X4400H, and have amazing sound. Would you care to comment on this set-up? Thanks!

dynamic range is dependent solely on the recording. don't confuse it with dynamic headroom, they're totally different things.

I like the ALPS RK50 analog volume pot.

I always wonder if a speaker could be created that doesn’t have a spider behind it, as surely this must cause a lot of sound being reflected back onto the cone, and therefore creating noise. Could a large magnet 🧲 actually be put all around the outermost part of the speaker, therefore leaving the cone without a spider at the back? Just a thought!

Lol yes I was going to chirp in as well on that I think he meant fly by wire airbus series stuff lol. But yeah we get what he means. He’s mr hi-fi not Dr plane lol

been a huge fan for a long time ! i'm a maitence worker in decent sized automobile factory in Kentucky Montaplast and I was wondering why these a.c components amps/integrated amps don't have a.c. to d.c power the d.c. power is stronger and you have more control right?

Paul still never really addressed the real issue of gain matching a system. Given the same 100w amp, the difference between an 85dB pair of minimonitors, or 95dB Tannoys is 10dB on your volume pot.... and yes the last new NAD preamp I purchased just a few years ago has a motorized POT. It is a real issue sometimes, and you need to put a system together intelligently. If it were a big enough problem, I'd put a 5 or 10dB attenuator pad between my preamp and amp, so that the volume knob is around 2 o'clock at "full volume". The source also matters greatly... what's the output level of the CD player or Phono preamp? These will play into the gain equation. Too many small details for Paul to get into here though.

the F15 A and B models use cables and still flown today, no fly by wire on those and tremendous forces at 2.5 Mach + :)

Perhaps the person was meaning to ask about low ohm speakers vs standard ohm speakers (i.e 8ohm), instead of high efficiency vs low efficiency. Low ohm and high efficiency are not mutually exclusive. Low ohm also does not mean that you'll get higher maximum db for the same size/type driver vs. standard ohm rating. Low ohm usually does imply that your amp will strain much more to produce it's maximum db vs 8ohm. Low ohm pulls more current, generates more heat, etc on the amp. Many older designs using 8ohm drivers with horns, could achieve well over 100db/watt. Low ohm speakers tend to be more reactive and as such are great for subwoofer application and movie sound effects playback. Other than that, a 4 ohm speaker has little to no advantage over an 8ohm speaker when it comes to frequency range from 30hz to 20Khz.

100-600 watts is AVERAGE? No wonder neighbors parties are so loud!

Wow this was f* interesting ! What Paul & his team are doing on the BHK preamp is actually using a potentiometer (no signal is going through it of course, right?) and via this pot we can change the first amplification stage's gain, right ? So in general, there're 2 steps doing it right, can somebody confirm ? Step1: equalize output stage gains according to speaker sensitivities, when possible also through the same trick, when not possible, then via a pot probably (attenuating instead of gain changing). 2. When gain levels are corrected according to speaker SPL-s and system is flat, use a preamp with a pot which alters the overall gain of the individual ways on their input stages (we're after the active crossover already) or better said: do the gain-changing trick on the preamp's output stages via this pot. Or am I misunderstanding the concept ?

Never had an issue with pots, just feed them into a proper buffer stage and your done. I mean how can you stuff up the sound going through a pair of resistors - amplifiers are full of them (admittedly many just pass DC, not the signal as such), Where you can go wrong is feeding a speaker via a fader, as the speaker looses all the damping factor from the amp. It gets worse with complex loads where the speaker impedance varies wildly with frequency, where as the fader kind of assumes a constant load - ouch. If you have a volume pot on a pre-amp that then goes straight to an output socket, then it's feeding a shielded interconnect that have capacitance, Ouch, you've just created an R-C filter - probably not what you intended. A volume pot should feed a relatively high impedance, near zero capacitance stage and you'll be right. On the other hand, what's going on inside those volume control IC's - many are just a ladder network of resistors, so you have basically the same thing as an old school pot, the only advantage, apart from easy remote control, is it won't get scratchy with age, dust is no where a big an enemy as it used to be - especially with open slider pots. For me a nice plastic film pot is the best, no non-linear bits to worry about - just load it properly. With the other side of this story - high efficiency speakers - well high efficiency drivers, what are they primarily designed for, as many I see are more intended for sound reinforcement and sacrifice linearality for sheer punch. great in a pub, not much use otherwise. If we're talking respectable brands like Klipsch etc. well now you can get decent sound levels from small boutique valve & other amplifiers - why use a system that needs over a hundred watts to sing, as you then limit yourself in amplifier selection.

Lol. We won't let you hear the end of the 747 physical cable system. Lol Yes, you point stands still though, because there is mechanical assistance.

Why/how are POTs bad? I don't understand.

I'm interested in your opinion and view upon some mid/high end studio monitors like the Eve SC307's or the Adam S3XV's ? Are they comparable with the systems you create at PS audio? Thanks in advance

Most systems have too much gain.. It can be more apparent with high efficiency speakers. So one needs to adjust the gain structure of the system - so it won’t “harm the sound” by limiting the range of the volume pot and starts ‘shouting’ early on.. JMO.

average power amplifier 500W? what?

Holy shit! I thought this cat was pretty knowledgeable but now he’s dogging horn loaded speakers. I’ll tell ya something for an absolute 1000% fact and that’s that my Klipschorns will make any speakers these guy’s ever produce sound like fisher price in comparison. No one has ever been able to disprove the fact that horns are far more effective and efficient at accurately reproducing sound. It’s like trying to disprove gravity. Never going to happen

Paul, what about adding a 4ohm fix resistor to a 4ohm tweeter to match a 8 ohm woofer in a diy speaker. Does that have sound?

PAUL please talk about the difference between High feedback and Low feedback Amplifiers!!! I saw a carver amp and it said it was low feedback but I thought amps needed alot of feedback to work correctly! what gives?

There are other potential problems with high efficiency loudspeakers. If there is any crossover notch distortion in a class AB amplifier it will be a higher percentage of the signal at any loudness level. If there is any residual noise when the amplifier is at zero volume, it will be louder. Tube amplifiers are more prone to these problems than solid state but transistors are not immune. One problem with output stages of tube amplifiers is performance drift. The best bass design is acoustic suspension but that is inherently inefficient design. Higher efficiency woofers are generally ported or horn designs. The acoustic suspension design wastes power by using aerodynamic drag pushing and pulling air between the fibers in the stuffing. This dampens resonances. The cones are generally heavier as well to keep the free air resonance frequency low and the system F3 low.

Anyone wanna tackle transformer based volume controls?

How long a speaker is usable, if no damage done through rough handling?

The best sounding speakers I've ever owned were high-efficiency speakers and horn loaded speakers. A pair of Altec Lansing Voice Of The Theater speakers which I had back in the 1970s. Nowadays I don't think they are as important as they used to be. Since we have almost an unlimited power available to choose from for power amps. Whereas back in the 1970s you rarely ever saw a hi-fi amplifier rated at over 200 or 250 watts RMS @ 8 Ohms per channel. Most were 100 watts or less.

Two things are constant. A nay for horns and a yea for subwoofers.

Oh fuck great, I have a stupid Pre amp from the 86 (Yamaha C-65) and High-efficiency speakers on the way... just too late.

That didn't really tell us why most speaker manufactures build speakers with low efficiency ratings!

He doesn't like klipsch speakers, because it's using horn

I don’t know any audiophiles (granted I don’t know many people in general) who like high efficiency speakers. HE speakers are good for budget-minded consumers with small amps. AFAIK, efficiency and damping are inversely correlated. Not so good.

Not a fan of horns? Waaaaaaaaaaaaaaat?!

Paul, maybe you don't like horns because you reached that conclusion years ago and it's stuck. Biases stick. You should check out some modern speakers with horns. I think that you will reconsider.

Sound cannot be "harmed".

I suppose if you are using high power solid state amplifiers it might be an issue since you are close to the crossover distortion but with a decent SET absolutely no problem.

Amusing when someone talks about 'horn' drivers. as if all horns, every one ever made, by anyone, anywhere at anytime .. Are All the Same?!?! .. lol These folks always like to hold their hands cupped next to their mouth as they inform us all, that all horn drivers sound like this - and they are all the same. Come on man...

Diddorol......Diddorol......Diddorol....... My next set up is going to consist of a high quality mixing console and a power amp. All sorted, no more issues.

I personally prefer high efficiency, but not too much, 100 is already too much, constipated British are 84 or less, and you can hear it from the sound, constipated, no thanks.

If the sound is bad at low volume levels, the amplifier design is bad. The problem is that impedance sensitive inputs which BJTs (FET and tube inputs do much better because the input impedances are extremely high and does not affect the internal function of the device) tend to alter their overall linearity and response for reasons I do not have the time and space to explain here. If any know the physics of BJTs, think "base width modulation". Any way, the main problem with resistor potentiometers is noise. In partial support of this, I read an article where a tube amp and a solid state amp of the same power (about 300 watts per channel) and specs were compared. The solid state amp had a sweet spot in volume level (again due to bwm) which was a loud setting, where the tube amp sounded the same at low level as well as loud. As the engineer doing the test said, the tube amp, when it got louder, sounded more and more live.

Second like :)