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How does a tube's need for bias change with age?
How does a tube's need for bias change with age?
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Old 20th November 2019, 05:18 PM   #21
kodabmx is offline kodabmx  Canada
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How does a tube's need for bias change with age?
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
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Old 20th November 2019, 06:08 PM   #22
6vheater is online now 6vheater
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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.

Quote:
Originally Posted by kodabmx View Post
A good sub will rattle the windows
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.

Last edited by 6vheater; 20th November 2019 at 06:17 PM.
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Old 20th November 2019, 06:44 PM   #23
kodabmx is offline kodabmx  Canada
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How does a tube's need for bias change with age?
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).

Last edited by wintermute; 21st November 2019 at 09:57 AM. Reason: profanity
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Old 20th November 2019, 07:47 PM   #24
6vheater is online now 6vheater
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Quote:
Originally Posted by kodabmx View Post
Bass response is directly related to SPL in your **** ears.

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.

How Hi-Fi do you need the sound to be when you're talking about 10s of Hz?!
Your logic is flawed.
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...

Click the image to open in full size.

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.

Click the image to open in full size.

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!

Last edited by wintermute; 21st November 2019 at 09:56 AM. Reason: profanity in quote
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Old 20th November 2019, 11:58 PM   #25
kodabmx is offline kodabmx  Canada
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How does a tube's need for bias change with age?
As soon as you said "audio is not audio" I lost interest. Audio is any sound at all so we'll have to agree to disagree.
Have a nice day, sir.

Last edited by kodabmx; 21st November 2019 at 12:20 AM.
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Old 21st November 2019, 12:23 AM   #26
Chris Hornbeck is offline Chris Hornbeck  United States
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Quote:
Originally Posted by 6vheater View Post
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.

Actually, this isn't even remotely true.


All good fortune,

Chris
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Old 21st November 2019, 07:40 AM   #27
Wavebourn is offline Wavebourn  United States
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How does a tube's need for bias change with age?
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.
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Old 21st November 2019, 08:12 AM   #28
disco is offline disco  Netherlands
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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.
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Old 21st November 2019, 08:32 AM   #29
mandu is offline mandu  Singapore
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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
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Old 21st November 2019, 12:24 PM   #30
mondogenerator is offline mondogenerator  England
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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!
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