Here are the specs... Energy Reference Connoisseur RC-70 Surround Speaker System Specifications | Sound & Vision
You use the acoustics of the room. Nobody lives in an anechoic chamber. The Polk RTIA9 is rated from 18Hz BTW... A good sub will rattle the windows at 10Hz in here (think dual 12" car box, and 400W...)
I don't listen to organ music, but I listen to plenty of drum and bass/jungle/etc. Most of which has LF sine wave bass.
Why don't you try this track out and tell me how well your system reproduces the lowest frequency. Mine hurts my damned head
YouTube
You use the acoustics of the room. Nobody lives in an anechoic chamber. The Polk RTIA9 is rated from 18Hz BTW... A good sub will rattle the windows at 10Hz in here (think dual 12" car box, and 400W...)
I don't listen to organ music, but I listen to plenty of drum and bass/jungle/etc. Most of which has LF sine wave bass.
Why don't you try this track out and tell me how well your system reproduces the lowest frequency. Mine hurts my damned head
YouTube
Oh grief, it's all I needed, a lecture on how to do audio, a load of commercial PR and speel, then some mpeg video from some lame dude on you tube in lo-fi.
I don't need such lectures when I test my own stuff with a DAW, studio microphones, hi res 24bit sound, and went to a lot of trouble to optimise it all, port lengths, stuffing, you name it.
All done in house.
Well no, you don't know how bass works.
It reproduces the REAL frequencies, not some sort of harmonics and doublers, and usually doesn't rattle windows at all.
When I see people talking about 7" woofers I just turn off.
Bass response is directly related to CONE AREA, but of course it's totally impossible to hear true bass notes in a car, because the space is simply NOT BIG ENOUGH.
I see in most Hi-end shops it's exactly the same problem.
Everything in the wrong places, the listening room an acoustic disaster...and so on.
It takes a HUGE speaker to get that cone area and use it properly.
The pair of mine would take up the entire interior of a car, leaving no space and weigh as much as the engine!
In this room where they are, I have to stand in the corridor or I can't hear those frequencies at all.
I listened to the most expensive Tannoys out there..
Westminsters v expensive.
Huge.
Boring, lousy tame sound.
Mine has nearly 3x the cone area of one of those.
Do you have any idea of the wavelength of an organ note...?
well, here's the clue 16ft or on occasions 32ft....
How big is the average big car? about 5m from end to including the engine and lots of bits that are not available. 5m = 15ft....the WHOLE CAR, not the internal space, so it is proveably an impossiblity to reproduce anything but harmonics of the fundamental.
In most rooms it's the same story.
I hear the kind of stuff in that video driving past on the street every day.
BORING.
I don't want this interesting thread turned into a p...ing competition so I will leave it there and unsubscribe.
I read some of the stuff from Polk, Energy this and that, inc the claims.
Seen that, read the macho PR, turned me off properly.
I don't need such lectures when I test my own stuff with a DAW, studio microphones, hi res 24bit sound, and went to a lot of trouble to optimise it all, port lengths, stuffing, you name it.
All done in house.
Well no, you don't know how bass works.
It reproduces the REAL frequencies, not some sort of harmonics and doublers, and usually doesn't rattle windows at all.
When I see people talking about 7" woofers I just turn off.
Bass response is directly related to CONE AREA, but of course it's totally impossible to hear true bass notes in a car, because the space is simply NOT BIG ENOUGH.
I see in most Hi-end shops it's exactly the same problem.
Everything in the wrong places, the listening room an acoustic disaster...and so on.
It takes a HUGE speaker to get that cone area and use it properly.
The pair of mine would take up the entire interior of a car, leaving no space and weigh as much as the engine!
In this room where they are, I have to stand in the corridor or I can't hear those frequencies at all.
I listened to the most expensive Tannoys out there..
Westminsters v expensive.
Huge.
Boring, lousy tame sound.
Mine has nearly 3x the cone area of one of those.
Do you have any idea of the wavelength of an organ note...?
well, here's the clue 16ft or on occasions 32ft....
How big is the average big car? about 5m from end to including the engine and lots of bits that are not available. 5m = 15ft....the WHOLE CAR, not the internal space, so it is proveably an impossiblity to reproduce anything but harmonics of the fundamental.
In most rooms it's the same story.
I hear the kind of stuff in that video driving past on the street every day.
BORING.
I don't want this interesting thread turned into a p...ing competition so I will leave it there and unsubscribe.
I read some of the stuff from Polk, Energy this and that, inc the claims.
Seen that, read the macho PR, turned me off properly.
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Bass response is directly related to SPL in your **** ears. Why can you make a 4" driver shake a house if you use a box the size of an arcade game? Using your logic, I'd need a 2 KM antenna to receive AM radio, and headphones wouldn't products ANY bass whatsoever being 1mm from your ear canal. but whatever you say...
Energy speakers like the RC70 were designed in collaboration with the NRC. If that means something "macho" to you, that's fine...
As far as the test track, it's simply low frequencies in succession. Why would that not be boring musically? Use a **** tone generator if you want to critique "lo-fi" youtube videos. How Hi-Fi do you need the sound to be when you're talking about 10s of Hz?!
The average car has garbage acoustics, and a LOT of noise. You need high power to drown it all out. Also 15ft length translates into 1000's of cubic feet of volume. Simple math man. Your logic is flawed IMHO.
You remind me of someone who told me not to tap floppy discs because the information would fall off (using the logic that screws on a magnet fall off when you hit the magnet hard enough).
Energy speakers like the RC70 were designed in collaboration with the NRC. If that means something "macho" to you, that's fine...
As far as the test track, it's simply low frequencies in succession. Why would that not be boring musically? Use a **** tone generator if you want to critique "lo-fi" youtube videos. How Hi-Fi do you need the sound to be when you're talking about 10s of Hz?!
The average car has garbage acoustics, and a LOT of noise. You need high power to drown it all out. Also 15ft length translates into 1000's of cubic feet of volume. Simple math man. Your logic is flawed IMHO.
You remind me of someone who told me not to tap floppy discs because the information would fall off (using the logic that screws on a magnet fall off when you hit the magnet hard enough).
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Well despite the torrent of uncalled for abuse, lots of ad hominem and all, lets do some physics shall we?
Mpeg Audio is NOT audio it's an even more approximate severe dented approximation of a waveform which has gone thru lots of brick wall filters, algorithms and who knows what to spit back at you an approximation of some far removed analogue original.
It might strike you as strange, but human hearing is entirely analogue, it responds to air pressure, and differences of phase and timing for those of us lucky to have 2 good healthy ears.
It's not linear, but I won't go into that now.
It's highly possible the mpeg audio on that you tube hurts your ears, because that's precisely what it is,- utter crap.
I have a signal generator which generates pure tones, exactly of those frequencies and that doesn't sound even remotely as bad and painful as that piece of rubbish on you tube...but hey that 's what it is.
You TUBE videos with audio samples in are utter crap.
It all makes me look in disbelief when some numpty is trying to post some dreadful audio and video clip of an amp or guitar and then has the nerve to turn around and ask..."can't you tell the difference between this amp and that or this guitar and that...."
Now,-
If somehow you imagined your ears could tune into AM radio. lets's pursue the logic of this shall we say 10mhz?
It would entail having a tuned circuit in your brain which enables you to differentiate accurately the exact WAVELENGTH of that station and can work at RF, which doesn't work at the speed of sound.
It's exactly 29.9792458m, which some people will remember is in the high short wave band.
There's of course a big difference. Radio waves travel at the speed of light.
299,792,458 m/s
Sound waves, well as we all know from lightning and thunder travel at the speed of sound - approx 1 mile every 5 secs at sea level and normal temps.
This does matter, because I really dislike people comparing apples and oranges then saying they are smart.
The way you can tune into that radio station is taking a wacking great long length of wire and coil it up to make a tuning coil.
It's not 2km long, but it's some multiple of a 1/4 wave, then you need an aerial, usually made of ferrite which multiplies the signal quite a bit in a certain freq band.
We then tune it with some capacitance so as we don't select 15 different stations simultaneously.
So yes you do need quite a LONG compact bit of wire to listen to a radio on 10mhz, get it,
I love Sengspiel's site, it expains good stuff simply...
Now the problem with AIR, is it's not really linear, it varies speed with temp, the wavelength of sound in air are a similar wavelength to RF, but much much lower frequency and it changes its speed with Temperature, which is why concert A is now 440hz (or unofficially 442) , whereas decades ago, when concert halls (like in china today are not heated) it used to be 435 or even lower.
(Speed of sound in helium is different again, as in water..but I am diverging more and more)
So let's find how low is a 10m wave? (that's about 30ft!).
Answer about 32hz, so for you to get a half wave length is going to need at least 5m.
Next let's go lower right down to those 18hz your speaker claims it can reproduce?
(we don't know it it really is, or it's just a mass of distortion as most are, and in any case you cannot hear 18hz.).....
Here we have a wavelength nearly twice longer closer to 60ft!
Even if you can hear multiple bounces off the walls, the half wave is hardly gonna register.
The ear is pretty darn good at mistaking harmonics for fundamentals, so that is what you are hearing...
Like the tuning coil in your radio your room is just not tuneable to get enough space in there to hear the fundamental, even if your speakers could actually reproduce it with any accuracy at all.
As for NRC, I don't care what twaddle is being yacked at marketing depts.
Marketing depts are made for telling lies.
Physics is physics and you can't change it.
Now you will understand why the biggest organs in the world are installed in some of the biggest rooms in the world,- places like Notre Dame, before it went up in smoke...
You can hear an organ develop in St Paul's cathedrale London, but sure as anything, unless your room is big enough you won't hear 20hz.
EVER.
I won't even go into the ins and outs of headphones, velocity and pressure sensitivity and the fact headphones are clamped on your ears, whereas speakers are some metres away from your ears....
I also thought this was about tube bias...oh well!
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I don't hear my sub (concrete horn under the floor), I feel it. Wavelength in the room does not matter. It matters in terms of resonances in the room, that's it. What matters, the volume of displaced air. Th bigger is the area of the cone, the shorter it's excursion is needed for the same SPL, and vice verse, for drivers with smaller area of the cone longer it's excursion is needed.
Do not be ashamed to open Feynman's lectures for kids if you forgot something. Neither ads nor popular articles in magazines can replace that.
Do not be ashamed to open Feynman's lectures for kids if you forgot something. Neither ads nor popular articles in magazines can replace that.
Not too enthusiastic about church organs I find myself attracted to the sound produced by double bass. The lowest note of a double bass is an C1 (≈33 Hz), being within about an octave above the lowest frequency that the average human ear can perceive as a distinctive pitch. 33Hz equals a wavelength of circa 9 meter, in a often encountered living that would take a bounce of 1x and a period of 30ms. Helmut Haas discovered that we can discern the sound source despite additional reflections at 10 decibels louder than the original wave front, using the earliest arriving wave front. This principle is known as the Haas effect: the nervous system combines all early reflections into a single perceptual whole allowing the brain to process multiple different sounds at once. The nervous system will combine reflections that are within about 35 milliseconds of each other and that have a similar intensity.
The cathode material is pulled by the plate, which in turn is the plate voltage applied. Higher plate voltage pull more material. As the cathode slowly looses material, the maximum plate current and power handling capacity is reduced.
The tubes were guaranteed for 1000 hours life. If you purchased a industrial tube the life is 10,000 hours. Example ECC81 vs E81CC. E81CC will have better cathode coating.
Lower filament voltage damages cathode more.
In push pull arrangement, the tubes usually age equally.
Class A operation in power tubes removes more cathode material.
All these are user dependent and vary with use.
Considering all these, you can re calibrate cathode bias only to a certain point which is already tubes down hill age., indicating that tube replacement are required
Regards.
The tubes were guaranteed for 1000 hours life. If you purchased a industrial tube the life is 10,000 hours. Example ECC81 vs E81CC. E81CC will have better cathode coating.
Lower filament voltage damages cathode more.
In push pull arrangement, the tubes usually age equally.
Class A operation in power tubes removes more cathode material.
All these are user dependent and vary with use.
Considering all these, you can re calibrate cathode bias only to a certain point which is already tubes down hill age., indicating that tube replacement are required
Regards.
6vHeater
In room or in car bass response is probably less about absolutes like cone area, than it is about ratios of displacement.
I.e. a 15" woofer with (VAS*xmax)= 5 litre in a 50 cubic metre room (5/50000) is a compression ratio smaller than a 4" woofer with (VAS*xmax) = 0.5 litre in a 2.5 cubic metre car cabin (1/5000).
The 4" can compress the air volume twice as easily, and assuming Fs and sensitivity are equal, in a purely hypothetical example, the 4" car speaker would go louder.
Which explains why my eyeballs vibrate in some Bassheads cars, but have never vibrates at a rock concert (at higher SPL), where my liver does!
In room or in car bass response is probably less about absolutes like cone area, than it is about ratios of displacement.
I.e. a 15" woofer with (VAS*xmax)= 5 litre in a 50 cubic metre room (5/50000) is a compression ratio smaller than a 4" woofer with (VAS*xmax) = 0.5 litre in a 2.5 cubic metre car cabin (1/5000).
The 4" can compress the air volume twice as easily, and assuming Fs and sensitivity are equal, in a purely hypothetical example, the 4" car speaker would go louder.
Which explains why my eyeballs vibrate in some Bassheads cars, but have never vibrates at a rock concert (at higher SPL), where my liver does!
I believe the OP picked up this gem of misinformation, from V. Capell book on loudspeaker design
Sorry Mr Wavebourn but on this point you are wrong,
You don't work in recording music or acoustics,
I will give an extreme example.
Put this big cabinet in your toilet, and see if it will reproduce the 30hz note...
IT WON'T. You might hear 60hz , 90hz, 120hz overtones because there is enough space for that, but 30hz NO....you just THINK you hearing the fundamental.
You "think" it is, but in reality all you are hearing is harmonics.
It's got zilch to do with displaced air, everything to do with wavelength.
Even a 1/4 wavelength will not find its space in there, below which the ear cannot hear it.
You can put as much sound pressure and displacement in the toilet as you like, until the walls shake and the toilet door blows off, but you will NOT hear the fundamental.
You have the classic confusion of amp & speaker makers, not knowing the difference between displacement of air, SPL, and development of waveforms.
They require space, exactly as the transmitter aerial requires space and the right length of wire to transmit a radio wave properly.
Put the wrong tuned circuit on there, you have a huge mismatch and nothing comes out!
You can put as much power in as you like, but nothing will transmit at the right frequency,but you might make your neighbours TVs go completely haywire.
A speaker is not a receiver it's a transmitter and exactly the same physics holds.
Doesn't explain anything at all.
A 4"
makes me laugh hearing such a term used.
Have you ever actually MEASURED anything?
I mean, properly with Bruel & Kjaer Microphones using proper calibration, or a proper calibration microphone used to measure SPL.
They are quite expensive toys.
Some of us actually work in the industry.
Actually if you like to know because there are laws in Europe making it illegal willingly to damage the hearing of people permanently by some of the idiotic tests I see discussed here.
Maybe you meant to say 10MHz?6vheater said:
No. You don't need a great long length of wire. It is not some multiple of a 1/4 wave, coiled up.
10mhz yes. 10MHz (which is 29.9792458m wavelength, as you said) only needs a short piece of wire. 2 or 3m will be fine, and you can get away with less.
In most cases the emission wearout mechanism is not the cathode surface having material physically pulled off it by electrostatic forces, but metal ions diffusing back into the oxide material.mandu said:
Not really true. A transmitter antenna needs to be a sufficient size to get a high enough radiation resistance to allow for efficient coupling to it. A smaller antenna will still radiate just fine, but you will lose power in the matching network.6vheater said:
Your point is? In some industries there is poor correlation between experience and understanding. Audio is one such industry.
The OP asked about tubes, and which way the bias would shift over time. There were several posts discussing the decline in emission and Gm over time requiring less negative bias over time to produce the same current. This the normal case with a tube which was manufactured with pure materials and a good vacuum.
Many modern production tubes, and many from the last days of tube manufacturing were not always well manufactured. Dirty materials, and minimum cost manufacturing were often the norm. Some NOS tubes are now 50 to 100 years old. Their vacuum isn't what it once was.
A contaminated vacuum will contain material (including air) which can ionize. This produces the blue / purple glow often seen INSIDE the plate structure on some tubes. A deep blue glow ON THE GLASS itself is a different and totally harmless phenomenon. Running a tube harder (hotter) will INCREASE the rate at which trapped ions are released from the materials inside the tube. Obviously a poorly constructed tube has more junk inside to begin with, so heating them up starts the inevitable march toward a red plate runaway failure.
This ionization will create a path for grid current to flow which will REDUCE the bias on the tube causing an increase in plate current. There is a reason why most tubes have a "minimum grid circuit resistance" spec. That resistance forms the path to bleed off excess grid current before it can start a runaway event. Did Leo Fender and others observe this spec?????? Do old guitar amps eat tubes????
Even in properly constructed amps that are operated within (but close to) the tube manufacturers ratings, some of today's new production tubes will start to exhibit bias creep, a slow but noticeable increase in tube current over time. This is more common in class A amps since their average dissipation is higher than other amps. Once a tube starts exhibiting this phenomenon, it should be replaced, or it will eventually go into a red plate runaway possibly damaging other parts.
As for big bass from small speakers....Yes, crank that small speaker to somewhere near Xmax, and it will distort. Keep it well out of that range and you can produce mostly fundamental tones. Running small speakers in a near field situation can make substantial bass. Can you get 95 db at 1 watt from a 4 inch woofer at 20 Hz, no, the physics won't allow it.
So do I. I started recording live music, mostly rock, in the mid 90's with Cakewalk software and a Pro Audio Spectrum 16 card. Been doing it ever since. My 90's vintage Yamaha NS-10M Studio near field monitors can produce 40 Hz with minimal distortion....at a low level. Yes, the response drops like a rock below 70 Hz, but they are still clean at 40 Hz. My daughter played drums back then and the Yamahas did a better job on faithfully reproducing her drums than all the others I tried, so I bought a pair....still have them.
Today I have a pair of IK Multimedia iLOUD micro monitors on my DAW in addition to the Yamahas. They use tiny 3 INCH woofers that are flat to 45 Hz thanks to modern DSP tricks. No, they are not going to shake the walls, or crank out a 27 Hz organ note, but they do very well despite their size. They DO produce real clean bass at close range. Their specs show a maximum SPL of 88 db at 45 Hz at 10% distortion from a distance of about 2 feet (near field). I have no reason to dispute their data.
I have not tried their new MTM version, which should do much better due to the 4 INCH WOOFERS, nor will I until I can find them for far less than list price.
IK Multimedia - iLoud Micro Monitor
Many modern production tubes, and many from the last days of tube manufacturing were not always well manufactured. Dirty materials, and minimum cost manufacturing were often the norm. Some NOS tubes are now 50 to 100 years old. Their vacuum isn't what it once was.
A contaminated vacuum will contain material (including air) which can ionize. This produces the blue / purple glow often seen INSIDE the plate structure on some tubes. A deep blue glow ON THE GLASS itself is a different and totally harmless phenomenon. Running a tube harder (hotter) will INCREASE the rate at which trapped ions are released from the materials inside the tube. Obviously a poorly constructed tube has more junk inside to begin with, so heating them up starts the inevitable march toward a red plate runaway failure.
This ionization will create a path for grid current to flow which will REDUCE the bias on the tube causing an increase in plate current. There is a reason why most tubes have a "minimum grid circuit resistance" spec. That resistance forms the path to bleed off excess grid current before it can start a runaway event. Did Leo Fender and others observe this spec?????? Do old guitar amps eat tubes????
Even in properly constructed amps that are operated within (but close to) the tube manufacturers ratings, some of today's new production tubes will start to exhibit bias creep, a slow but noticeable increase in tube current over time. This is more common in class A amps since their average dissipation is higher than other amps. Once a tube starts exhibiting this phenomenon, it should be replaced, or it will eventually go into a red plate runaway possibly damaging other parts.
As for big bass from small speakers....Yes, crank that small speaker to somewhere near Xmax, and it will distort. Keep it well out of that range and you can produce mostly fundamental tones. Running small speakers in a near field situation can make substantial bass. Can you get 95 db at 1 watt from a 4 inch woofer at 20 Hz, no, the physics won't allow it.
So do I. I started recording live music, mostly rock, in the mid 90's with Cakewalk software and a Pro Audio Spectrum 16 card. Been doing it ever since. My 90's vintage Yamaha NS-10M Studio near field monitors can produce 40 Hz with minimal distortion....at a low level. Yes, the response drops like a rock below 70 Hz, but they are still clean at 40 Hz. My daughter played drums back then and the Yamahas did a better job on faithfully reproducing her drums than all the others I tried, so I bought a pair....still have them.
Today I have a pair of IK Multimedia iLOUD micro monitors on my DAW in addition to the Yamahas. They use tiny 3 INCH woofers that are flat to 45 Hz thanks to modern DSP tricks. No, they are not going to shake the walls, or crank out a 27 Hz organ note, but they do very well despite their size. They DO produce real clean bass at close range. Their specs show a maximum SPL of 88 db at 45 Hz at 10% distortion from a distance of about 2 feet (near field). I have no reason to dispute their data.
I have not tried their new MTM version, which should do much better due to the 4 INCH WOOFERS, nor will I until I can find them for far less than list price.
IK Multimedia - iLoud Micro Monitor
To throw som figures in this thread :
Sometime ago a replaced a quad of 6550 in my amp, they have been active 4324 hours.
They still kept bias, adjusted about 10%, that still measures useful in maximatcher.
Tubes are kept as proof of evidence.
During this time 2 GZ34 is replaced, 3 12au7 clones ( RCA something) as one of them started
to hum from filament<>cathode leakage.I replced all 3 as "service procedure".
( time measured with a digital hour-meter installed when i built the amp)
Sometime ago a replaced a quad of 6550 in my amp, they have been active 4324 hours.
They still kept bias, adjusted about 10%, that still measures useful in maximatcher.
Tubes are kept as proof of evidence.
During this time 2 GZ34 is replaced, 3 12au7 clones ( RCA something) as one of them started
to hum from filament<>cathode leakage.I replced all 3 as "service procedure".
( time measured with a digital hour-meter installed when i built the amp)
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One of my SSE amps runs Electro Harmonix 6550's. It is usually biased at about 80 ma with 440 volts B+ for about 30 to 32 watts of dissipation.
For nearly 3 years it was the amp that went between my PC and the Yamaha NS-10's, so it got used whenever the PC was on (several hours a day). It's now 12 years old and has been used off and on since then and still has the same tubes in it. The pretty blue glow is gone, but they still work fine.
Some SSE users have had red plate runaway occur in new production Tung Sol KT88's after a couple of years.
These are both New Sensor tubes. Some batches are good, some not so good.
For nearly 3 years it was the amp that went between my PC and the Yamaha NS-10's, so it got used whenever the PC was on (several hours a day). It's now 12 years old and has been used off and on since then and still has the same tubes in it. The pretty blue glow is gone, but they still work fine.
Some SSE users have had red plate runaway occur in new production Tung Sol KT88's after a couple of years.
These are both New Sensor tubes. Some batches are good, some not so good.
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