You use efficiency incorrectly...sorry but you do. This confuses the discussion because you want to use it your way rather than the accepted definition. dB for 1 watt/1meter is a spec for Sensitivity. They started to twist sensitivity to be dB for 2.83V/1meter to make low impedance speakers seem more sensitive than they are but it is also Sensitivity (2.83V was not pulled out of a hat as it is the voltage of an 8 ohm watt). Efficiency is given in % (as in % electrical power converted to acoustic power). The rest is radiated as heat.
SET amp owners thread
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Efficiency defined as 1 watt/1 meter has been a specification for the measurement of loudspeakers for quite some time- since the 1950s or thereabouts. The sensitivity spec (2.83V/1 meter) came into use during the 1980s, when solid state amps capable of acting as a voltage source became more common. But speaker manufacturers still use the efficiency spec as opposed to the sensitivity spec (and there are a few that use the two interchangeably, as if they don't know the difference).
You are also correct about efficiency but when measuring loudspeakers efficiency is rarely presented as a percentage.
Seems like phase and insertion loss of passive crossover ( if used ) as well as efficiency are the three specs mostly relevant to this thread... Usually you get one at best
No , sorry this is incorrect as I pointed out. Sensitivity is in dB (the unit conditions don’t change this but can be used to confuse people if they don’t know basic electronics) and efficiency is in %..
I see you are using an Elrog 5U4G rectifier in your ATM 300R. What has been you experience with this tube?
Of particular interest is that Air Tight specifies a 5U4GB which adds a slow-start mechanism and as I understand has different electrical specs versus the 5U4G. It was my understanding that Air Tight advised to only use the 5U4GB not to substitute. Obviously, this is not exactly the case as you seem to be happily using the 5U4G.
Well I don't imagine I can change your mind if I provide examples... and since the efficiency spec is rarely used these days its of little consequence.
Klipsch states it clear on their website that speaker efficiency is the wrong way to describe sensitivity...a number of pro sites say the same and there are online calculators for the conversion...not much you show me to convince otherwise I think.
Klipsch simply isn't expecting people to use SETs or other zero feedback tube amplifiers which don't respond to the voltage rules. The Efficiency spec went out years ago (1980s, as I mentioned earlier) about the same time that the industry was really shifting over to the voltage rules instead of the older power-based rules. So the 600 ohms balanced line termination standard went out about that time too.
Back in the 1950s it was MacIntosh and EV that led the move to the voltage rules (which I call the Voltage Paradigm, since anything outside a paradigm is considered blasphemy; at this point the Power Paradigm is such and with it, the efficiency specification). During this period of transition a number of amps were made with variable damping- Fisher made a few and EV as well. The Damping control allowed the amp to be a voltage source at one end of the range (by cutting power in half as impedance is doubled rather than doubling power as impedance is halved- this is part of why tube power is so expensive...) or a current source at the other end of the range (in some case maybe only a power source as the amp might not have employed current feedback), and a power source at noon where the current and voltage feedback were in cancellation (which is the same as zero feedback).
You can tell a loudspeaker that is meant to accommodate amplifiers of the Power Paradigm persuasion. They will have controls and/or switches to change the output at various frequencies, usually a pot connected to the midrange or tweeter. These are common on vintage horn systems (my Classic Audio Loudspeakers have such controls). The controls are not there to adjust the speaker to the room, they are there to adjust the speaker to the voltage response of the amp, which is an unknown. The Voltage Paradigm sought to do away with this idea, to improve 'plug and play'. You can imagine with speaker level controls and variable feedback there was plenty of opportunity to get things wrong
SETs, being zero feedback tube amplifiers, tend to act more as power sources than anything else (no tube amp is a perfect power source BTW). Because they don't double power as impedance is halved (or halve their power as impedance is doubled) you have to be careful to find a speaker that works with them. Every person who has a successful SET system knows this; I'm simply explaining why. With such amps the sensitivity spec can be a bit misleading- a 4 ohm speaker that is rated 96 dB might seem attractive since the SET might have a 4 ohms tap, but the speaker is really 93dB by the old efficiency spec and 93dB really isn't enough efficiency to work with most SETs unless the listening room is pretty small or the playback is entirely nearfield. You can waste a lot of money making mistakes like that!
All very interesting Ralph...and completely beside the point! Again, dB in watt/m or V/m is a measure of SENSITIVITY...conversion of electrical watts to acoustic watts is EFFICIENCY and give in %.Klipsch simply isn't expecting people to use SETs or other zero feedback tube amplifiers which don't respond to the voltage rules. The Efficiency spec went out years ago (1980s, as I mentioned earlier) about the same time that the industry was really shifting over to the voltage rules instead of the older power-based rules. So the 600 ohms balanced line termination standard went out about that time too.
Back in the 1950s it was MacIntosh and EV that led the move to the voltage rules (which I call the Voltage Paradigm, since anything outside a paradigm is considered blasphemy; at this point the Power Paradigm is such and with it, the efficiency specification). During this period of transition a number of amps were made with variable damping- Fisher made a few and EV as well. The Damping control allowed the amp to be a voltage source at one end of the range (by cutting power in half as impedance is doubled rather than doubling power as impedance is halved- this is part of why tube power is so expensive...) or a current source at the other end of the range (in some case maybe only a power source as the amp might not have employed current feedback), and a power source at noon where the current and voltage feedback were in cancellation (which is the same as zero feedback).
You can tell a loudspeaker that is meant to accommodate amplifiers of the Power Paradigm persuasion. They will have controls and/or switches to change the output at various frequencies, usually a pot connected to the midrange or tweeter. These are common on vintage horn systems (my Classic Audio Loudspeakers have such controls). The controls are not there to adjust the speaker to the room, they are there to adjust the speaker to the voltage response of the amp, which is an unknown. The Voltage Paradigm sought to do away with this idea, to improve 'plug and play'. You can imagine with speaker level controls and variable feedback there was plenty of opportunity to get things wrong
SETs, being zero feedback tube amplifiers, tend to act more as power sources than anything else (no tube amp is a perfect power source BTW). Because they don't double power as impedance is halved (or halve their power as impedance is doubled) you have to be careful to find a speaker that works with them. Every person who has a successful SET system knows this; I'm simply explaining why. With such amps the sensitivity spec can be a bit misleading- a 4 ohm speaker that is rated 96 dB might seem attractive since the SET might have a 4 ohms tap, but the speaker is really 93dB by the old efficiency spec and 93dB really isn't enough efficiency to work with most SETs unless the listening room is pretty small or the playback is entirely nearfield. You can waste a lot of money making mistakes like that!
The more important consideration is that information be presented in a way which is USEFUL to the end user. The convention of expressing efficiency in decibels at one meter for a 1 watt input, and sensitivity in decibels at one meter for a 2.83 volt input, provides ALL of the relevant information the end user might need, with the possible exception of some pro audio applications.
For virtually all end users, expressing efficiency as a percentage adds ZERO useful information to the above, but it does add a layer of unnecessary obfuscation.
And since you mentioned Klipsch, the alarming discrepancies between their claims and John Atkinson's measurements indicate that semantic accuracy may be of academic interest only.
In my opinion.
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Apparently others thought exactly the same thing
In the past I encountered one other convinced that the % thing is the only way efficiency has ever been expressed when describing loudspeakers. I had zero success in convincing him of the history as well. But if you dig, you will find it so IMO this is a matter of having the will to cause the hand to move.
When you stop using tubes then the sensitivity expression is more useful. Having your feet in both worlds (Power vs Voltage - in this case being an avid user of SETs but persisting in using sensitivity when looking at loudspeakers) has got to be confusing- so I imagine in such a case the % thing would hold more sway, and its not helpful if the speaker manufacturer were to actually publish the %efficiency numbers since to make any sense of it, you'd have to do the log 20 thing to sort it out and most people don't even know about that! The thing is, the single most common mistake people make when going with SETs is settling for a loudspeaker that simply isn't efficient enough to really show off the amp.
The way I look at it, to convert from sensitivity to efficiency if the load is 8 ohms is no worries. When the load is 4 ohms then you have to subtract 3 dB. This is helpful in understanding if the speaker is going to work with the SET, especially considering that to do so effectively and in the best light, the maximum power of the SET should not be expected to go past 20-25%. That 3dB can make a difference! But IME you really want a higher impedance (16 ohms) when working with zero feedback tube amps as you'll get greater efficiency out of the output transformer and lower distortion at the same time.
If you have a 16 ohm load and the sensitivity is rated at 96dB, the actual efficiency is 99. That 3dB thing again, only this time in your favor.
Sorry Duke but the definition of efficiency for a loudspeaker is what it is and that is a ratio of acoustic power and electrical power in %. Both dB for 1 watt/meter and 2.83V/meter are just slightly different expressions of Sensitivity.
Audio magazines and some manufacturers started using the later to make speakers seem more sensitive than they really were because as we know 2.83V into 4 ohms is more than 1 watt. Plus there was a kind of assumption that amps which increase power into lower impedance would cover the discrepancy. However, by definition a dB rating is Sensitivity.
Efficiency in a gas engine is the ratio of mechanical power generated to chemical power put in and the rest as we know is heat waste. Same with a speaker where electrical power passes through resistance and makes a lot of waste heat (a big problem as we know regarding thermal compression) which reduces the conversion efficiency. It describes the losses involved in transformation from one energy type to another type. Useful for engineers but not consumers. Sensitivity is for consumers to have an idea how loud their speaker will play given X watts.
OK so we get a textbook definition of efficiency from @morricab. Would you please proved 2 or 3 examples of such in the commercial loudspeaker world ( your represented line AC maybe? ) and how we can use them?
I am not proposing to using efficiency for any speaker making decisions...manufacturers give specs in sensitivity either as dB watt/meter or 2.83V/meter.
The ELROG ER5U4G can also replace a 5U4GB. The 5U4GB can handle more current and more load capacitance than older 5U4. It does not have a different start characteristic. Directly heated rectifiers all start very quickly within seconds
Thomas
Thank you Thomas. Replacing the stock EH 5U4GB with a NOS RCA 5U4GB made a significant, positive SQ impact. So, now I think I will give the Elrog 5U4G a try.
Yes, no issues with the Elrog 5U4G in my Air Tight 300R. Between the 300B-Mo, Elrog Recti and NOS tubes I am really enjoying the 300R.
Thomas's customer service is top notch.
Zu Omen Dirty Weekend | Zu Audio | Hi-Fi audio speakers and cables hand built in the USA
Zu Omen Dirty Weekend loudspeaker is our hook, the best that can be done without making regrettable compromises in performance, materials or life-long quality.
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The last statement of your post (although with good intent) is false. The consumer will only get an approximation of sound pressure if the impedance of the speaker is 8 ohms; but if the speaker is 4 or 2 ohms the power they may need might have to be double or 4x more. You can't correct the statement using the word 'voltage' to replace 'watts' as amps are typically rated in watts rather than voltage.
With SET amplifiers this is particularly true since they do not behave as voltage sources!
The second paragraph in your post touches on an interesting topic that I've talked about for many years- the tendency for audio to dive to the bottom in the chase of the almighty dollar. I think the first example of this (anywhere near the hifi era) was when the industry went from field coils to permanent magnet loudspeakers, which are cheaper to produce. The next time was when it moved from tubes to solid state. At that time, amp manufacturers saw that they didn't need to make an output transformer and didn't need a filament circuit, allowing their amplifier to be considerably cheaper (sometimes 50% less) to produce, yet they got to charge 90% of the same money as they did for tubes. As solid state improved and 4 ohms became practical, we saw a big decrease in speaker efficiency, since building high efficiency speakers requires precision gaps and motor assembly (which makes them more expensive). All of a sudden much cheaper drivers (in particular, woofers) was possible. By using the voltage spec and promoting 4 ohm loads, the appearance was that the newer batch of speakers did not sacrifice so much efficiency.
In the old days when tubes were king, efficiency was really important because tube amplifier power is/was expensive. Today where amplifier power is inexpensive (500 watt amps are now common) efficiency is regarded by the industry as unimportant. These days 4 ohm speakers are far more common than 8 ohms. As an amplifier designer, I regard it as a bit of an epidemic, as the simple fact is that no matter what amplifier kind you have (tubes, solid state or class D) the distortion of the amplifier will be audibly higher into lower impedances, for example 4 ohms as opposed to 8 ohms. In high end audio, the goal is to get as close to the music as possible and 4 ohms flies very much in the face of that.
Klipsch, who as you know is one of the long-time horn speaker companies, begs to differ...Just one example but there are many more. ZU uses the 1 watt/1 meter efficiency spec since a lot of their market uses tubes.Zu Omen Dirty Weekend | Zu Audio | Hi-Fi audio speakers and cables hand built in the USA
Zu Omen Dirty Weekend loudspeaker is our hook, the best that can be done without making regrettable compromises in performance, materials or life-long quality.
The last statement of your post (although with good intent) is false. The consumer will only get an approximation of sound pressure if the impedance of the speaker is 8 ohms; but if the speaker is 4 or 2 ohms the power they may need might have to be double or 4x more. You can't correct the statement using the word 'voltage' to replace 'watts' as amps are typically rated in watts rather than voltage.
With SET amplifiers this is particularly true since they do not behave as voltage sources!
The second paragraph in your post touches on an interesting topic that I've talked about for many years- the tendency for audio to dive to the bottom in the chase of the almighty dollar. I think the first example of this (anywhere near the hifi era) was when the industry went from field coils to permanent magnet loudspeakers, which are cheaper to produce. The next time was when it moved from tubes to solid state. At that time, amp manufacturers saw that they didn't need to make an output transformer and didn't need a filament circuit, allowing their amplifier to be considerably cheaper (sometimes 50% less) to produce, yet they got to charge 90% of the same money as they did for tubes. As solid state improved and 4 ohms became practical, we saw a big decrease in speaker efficiency, since building high efficiency speakers requires precision gaps and motor assembly (which makes them more expensive). All of a sudden much cheaper drivers (in particular, woofers) was possible. By using the voltage spec and promoting 4 ohm loads, the appearance was that the newer batch of speakers did not sacrifice so much efficiency.
In the old days when tubes were king, efficiency was really important because tube amplifier power is/was expensive. Today where amplifier power is inexpensive (500 watt amps are now common) efficiency is regarded by the industry as unimportant. These days 4 ohm speakers are far more common than 8 ohms. As an amplifier designer, I regard it as a bit of an epidemic, as the simple fact is that no matter what amplifier kind you have (tubes, solid state or class D) the distortion of the amplifier will be audibly higher into lower impedances, for example 4 ohms as opposed to 8 ohms. In high end audio, the goal is to get as close to the music as possible and 4 ohms flies very much in the face of that.
Speaker Sensitivity
Speaker sensitivity—many times erroneously referred to as speaker efficiency—is used to determine the amount of power necessary to drive or operate a loudspeaker. It is a measurement of the amount ...
support.klipsch.com
Again, of course they do! As I pointed out earlier, even though Klispsch is in the business of higher efficiency speakers, they really don't expect that anyone will be using tubes with their speakers, although they are tolerant if you call them on the phone and admit to suchKlipsch, who as you know is one of the long-time horn speaker companies, begs to differ...
Speaker Sensitivity
Speaker sensitivity—many times erroneously referred to as speaker efficiency—is used to determine the amount of power necessary to drive or operate a loudspeaker. It is a measurement of the amount ...
But Klipsch did use the 1 watt/1 meter spec back about 50-60 years ago when such a thing was far more useful. My aunt owned a Bogen integrated tube amp with Klispch corner horns back in the 1960s and was one of my more formative exposures to what a more upscale system could do. I was interested in the system so she dug out the brochures which she still had on hand so I know this from that experience.
JBL spec'ced their L100 Century (the original, not the reissue) as
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