Because valves COMPRESS, and when they start to clip it doesn't sound too bad.
Anyone can see, as the anode current rises, and the anode voltage drops, the thing is just plain non linear.
The amount of anode load and the load impedance (ie. current) is constantly changing.
This is a dynamic load question so it's a bit like shooting at a moving target in the dark.
Add some negative feedback (ie. drop in overall gain, which is also freqency dependent), miller effects caused by triodes, supply rails that may be low impedance or may be a little higher than expected, and you have a recipe for something which is harder to quantify.
In layman's terms if you have a single HT rail of 600V and impose a strong conduction across it into a reactive load, then as the anode voltage approaches zero and the grid goes positive, the gain of the valve flattens off and the grid suddenly goes into current.
Call it what you may but you are introducing changes to the output signal level which it did not have entering the amplifier.
Maybe you can hear it, or in lots of cases imagining it, or it's plain bad design, or all at once?
Anyone can see, as the anode current rises, and the anode voltage drops, the thing is just plain non linear.
The amount of anode load and the load impedance (ie. current) is constantly changing.
This is a dynamic load question so it's a bit like shooting at a moving target in the dark.
Add some negative feedback (ie. drop in overall gain, which is also freqency dependent), miller effects caused by triodes, supply rails that may be low impedance or may be a little higher than expected, and you have a recipe for something which is harder to quantify.
In layman's terms if you have a single HT rail of 600V and impose a strong conduction across it into a reactive load, then as the anode voltage approaches zero and the grid goes positive, the gain of the valve flattens off and the grid suddenly goes into current.
Call it what you may but you are introducing changes to the output signal level which it did not have entering the amplifier.
Maybe you can hear it, or in lots of cases imagining it, or it's plain bad design, or all at once?
For someone who CLAIMS to know as much as you do, it's rather scary to see you writing this tosh.
How do you think the links are made between the transmitters all over a country giving broadcast FM (Digital PCM for at least 40 years).
ie. the entire broadcast feed line is digital.
Read please and look stupid just ONCE OK!
http://www.bbceng.info/Technical Reviews/pcm-nicam/digits-fm.html
You have no idea about dummy head recording which is no suprise as you just confessed to working in studios for 400 years.
Perhaps if you went outside and sniffed the coffee, you would realise learning to record properly comes by coincident techniques in natural acoustics (and people doing multi miking techniques like you presumably must do), have poisoned the entire audio recording industry.
(Again Gerzon on multi miking...)
I can only presume your dummy head recordings never worked out because you didn't have a clue what you are doing.
The French seem to have done marvels with it.
If you read some of the leading research on it from IRCAM instead of sounding out your EE pretensions like a foghorn on a november day, you might learn something.
Oh I forgot Electronic engineers can't learn anything because they know it all already including how to spell HEAR. 🙄
😀
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Ok, so I guess my hope of being able to understand as a layman is a bit of a pipe dream. In any case the affect is not imagined, nor is it minimal, it is dramatic.
I think we are all just guessing.
If you would post schematics of the two amps it might be possible to analyze them and determine exactly what is causing the difference you hear.
If you would post schematics of the two amps it might be possible to analyze them and determine exactly what is causing the difference you hear.
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It was always referred to as Radio Luxembourg amongst the youngsters I was involved with - perhaps it was Caroline but their broadcast frequency showed up on the dial where the text says 'Luxembourg' - old radios had foreign station names written up and down the dial in those days.
listening for differences without controls and blinding will almost always result in perceiving a difference
sometimes it simply is that there are differences in loudness, frequency response or clipping behavior
measurement of V at the speaker terminals lets you see those - and should lead to making changes to bring those behaviors technically closer for the 2 amps - up to their power limits
Too many variables involved to answer: "why does amp A sound different then amp B?"
All we have to go on is one constant, and that is that the two different amps have "almost equal" power rating.
Amplifiers topologies can have sonic attributes, if we could see a schematic then we could make a better assumption of why you hear a difference. I am not sure if you mentioned the speakers you are using but they are a big part of the equation.
All we have to go on is one constant, and that is that the two different amps have "almost equal" power rating.
Amplifiers topologies can have sonic attributes, if we could see a schematic then we could make a better assumption of why you hear a difference. I am not sure if you mentioned the speakers you are using but they are a big part of the equation.
For someone who CLAIMS to know as much as you do, it's rather scary to see you writing this tosh.
How do you think the links are made between the transmitters all over a country giving broadcast FM (Digital PCM for at least 40 years).
ie. the entire broadcast feed line is digital.
Read please and look stupid just ONCE OK!
The BBC PCM / NICAM Story
You have no idea about dummy head recording which is no suprise as you just confessed to working in studios for 400 years.
Perhaps if you went outside and sniffed the coffee, you would realise learning to record properly comes by coincident techniques in natural acoustics (and people doing multi miking techniques like you presumably must do), have poisoned the entire audio recording industry.
(Again Gerzon on multi miking...)
I can only presume your dummy head recordings never worked out because you didn't have a clue what you are doing.
The French seem to have done marvels with it.
If you read some of the leading research on it from IRCAM instead of sounding out your EE pretensions like a foghorn on a november day, you might learn something.
Oh I forgot Electronic engineers can't learn anything because they know it all already including how to spell HEAR. 🙄
😀
Stupid is the one who can't answer a simple question. And attacking typos is the last stand of a person who has no other ammo. Oh and dummy head recordings are complicated, I laugh again. FM radio has been around a lot longer than 40 years, so your comment about it being fed digitally for ever is WRONG. How many people have to tell you your wrong before you listen?
And by the way I have done dozens of stereo mic recordings of small classical ensembles. Your assumption about people you don't know and your attacks on them show your real colours. ( that's not a typo that's how we Canucks spell colour, so don't bother attacking my spelling again.)
You whole antagonistic and demeaning manner shows your immaturity. And the only reason I mentioned my EE was to answer your question if I knew any thing about mic pre workings. Just saying I did would not have been enough for you, I'm sure. Do you know anything about mic pres. Oh yea I'm wasting my time, you don't answer any questions.
I'd rather have an amp that can handle recordings that haven't been compressed and has a wider dynamic range than one that doesn't.
No experience with valve amps myself but dynamics certainly is an issue with chipamps and it seems to be dominated by one thing - power supply impedance.
I fired up a simulator to find out why this might be and it turns out that normal emitter follower output stages don't have as much PSRR as designers tend to assume. Perhaps the same is true for tube output stages?
I'm not an electronics guy but a DIYAudio friend that is explained why Class D amps don't handle dynamic range as well as ClassAB amps.
Sent from my iPad using Tapatalk
Sent from my iPad using Tapatalk
Do please share - sounds very interesting.
In my experience classD amps only lack in the HF region - they're gritty and harsh which can be improved with more caps on the supply. In the bass though they sound like they have more dynamics than classAB. At least to my ears.
In my experience classD amps only lack in the HF region - they're gritty and harsh which can be improved with more caps on the supply. In the bass though they sound like they have more dynamics than classAB. At least to my ears.
It's the interaction of human hearing with the distortion spectra of the heard sound - the ear/brain always tries to make sense of what it hears, and it "mentally" adjusts the relative volume of the sound elements it picks up, for maximum comfort and clarity. This is why high end systems sound dramatically different from each other, most of the time - you're hearing too much of the distortion injected by the playback chain, which varies enormously between the customised rigs. Very few reveal the underlying recording clearly - it may take listening to a finely tuned system to realise what the intrinsic "sound" of a recording is, which then gives one a solid goal to work towards.
Ok, I can follow that distortion will affect perceived loudness. I'll post schematics tomorrow. And low impedance power supplies makes sense in a way, too.
Thanks for the responses. I really do just want to learn through this.
One of my schematics will probably rile people up as the designer and his designs tend to polarize people left and right.
Thanks for the responses. I really do just want to learn through this.
One of my schematics will probably rile people up as the designer and his designs tend to polarize people left and right.
I think a little correction is due here.
Dynamics and resolution in Audio reproduction are 2 sides of the same coin, so an amplifier should at minimum be able to play back from FM stereo radio without clipping or attenuating the originally 13 bit based coding.
This in practice is probably the resolution limit of most "high end speaker" systems.
You didn't read the article?
I didn't specify stereo, which of course is what we were discussing of course.
You can read a lot more here:-
All You Ever Wanted to Know About NICAM but were Afraid to Ask
FM Mono transmission is of no earthly interest to anyone.
You can do that on short wave if you like!
Isn't it sad to see someone who says he has so much to offer, trying to contradict facts?
For your reference:- FM radio has been around for EXACTLY 60 years this year TODAY.
Today it's the 60th birthday.
What a wonderful way you have to celebrate it!
"BBC FM broadcasting officially began on 2nd May 1955 from Wrotham in Kent".
You delightfully forget that the BBC had numerous world firsts and were pioneers to this day in both stereo and surround sound.
To begin with the broadcasts mostly in mono went to the transmitter over dedicated analogue telephone cable.
This is still the case today for numerous local radios throughout Europe.
I like Gerzon was one of the few people in the UK that could actually listen to their surround broadcasts, though sadly not to the proms season in 1976, which according to critics wasn't great anyway.
I remember hearing Shakespeare "The tempest" in surround in 1977 and it was not so bad.
Next year will be the 40th anniversary of that experiment, which so far has not been improved upon on FM radio.
If you read carefully you will find out the BBC, being one of the leading laboratories in the world at the time, were some of the first to do satellite broadcast of concerts in Stereo using their NICAM system.
As far as we are concerned FM stereo radio really only became a national phenomenon throughout the UK with the introduction of digital transmission (which is for a lot of people here slightly before or after they were born), so my comment "FOR EVER" to all intents and purposes is completely correct.
I don't think anyone in the UK remembers FM mono transmissions any more, so analog FM audio to all intents and purposes is pre-history.
"NICAM stands for Near Instantaneously Companded Audio Multiplex"
Here is the digital system the BBC introduced, which was exported to the European continent also.
NICAM's unusual features
NICAM sampling is not standard PCM sampling, as commonly employed with the Compact Disc or at the codec level in MP3, AAC or Ogg audio devices.
NICAM sampling more closely resembles Adaptive Differential Pulse Code Modulation, or A-law companding with an extended, rapidly modifiable dynamic range.
"On the 14th of September 1972 the link from Broadcasting House to the Wrotham transmitter switched to the new BBC PCM (Pulse Code Modulation) system. This produced a dramatic improvement in sound quality – even on the UK link that had already probably been the best performing. Radio 2 from Wrotham also officially started broadcasting in stereo from Wrotham on 4th November 1972"
"by the 4th of August 1973 Sutton Coldfield and Wrotham were both using PCM links to broadcast high quality stereo on Radios 2, 3, and 4. This in turn meant that some of their lower power subsidiary transmitters also then provided improved output, although sometimes degraded by having to pass along a non-PCM section for the last part of their journey to the transmitter. By the end of 1975, PCM stereo links had come into operation for many other UK mainland transmitters. With Divis (Northern Ireland) and Tacolneston joining the party by the middle of 1976. Various other links were converted at later dates reaching into the early part of the 1980".
Using this technology the BBC made the FIRST live stereo international concerts by the end of the 1970s, at which point I imagine you were still walking around in shorts, or drinking from a baby bottle, so quite unable to know much more...
"In the process they achieved some significant historic ‘firsts’ that have since, sadly, largely been forgotten. Yet they represented important technological achievements.
One such event was a live broadcast of a concert given by Elton John in the Rossyia Hall in Moscow on the 28th May 1979. An experimental NICAM 1 system was used to send the audio for this from the concert in Russia back to Broadcasting House"
"The established PCM system multiplexed 13 audio channels into a 6336 kb/sec data stream. However by the early 1980s telecomms providers were starting to offer their own digital connection systems and it made sense to consider using these. One (CCITT standard) system provided 8448 kb/sec."
"
Each PCM channel was based on sampling the input analogue audio waveform at 32k samples/sec and generated 13-bit LPCM (Linear PCM) sample values. The sampling was dithered to suppress quantisation effects. The input to each analogue-to-digital convertor (ADC) was low-pass filtered to reject audio frequencies above 15kHz.
In principle a 13-bit linear PCM system should be able to provide a dynamic range (ratio of maximum clean signal to background noise) of the order of 78dB.
In practice the background noise level will vary depending on the details of how the system is implemented.
These days engineers concerned to totally remove unwanted effects like quantisation distortion or noise modulation would tend to add random ‘dither’ in a way that increases the noise level by around 3dB. The BBC PCM system used a more complex and ingenious approach that added less noise, but did expose the system to some low level effects."
"The system changed again in 2008 when it was “refreshed” and the outsourcing provided by Siemens. However throughout those changes, and up until now, the coding used for audio remains the same BBC-invented NICAM 3 digital coding."
You can read about it in the BBC article I linked above & in a book ISBN: 9780240516431 An introduction to digital audio.
FM stereo radio IS digital not analog, it's just some people believe otherwise.
QED.
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The BBC PCM was ( is ??? ) a very good system. Robust and compromises set by a musically trained listening team. The system selected had pumping effects at - 78 dB hidden by hiss as something they thought OK. The BBC said they were very surprised that Sony Philips never asked the BBC for advice when designing CD.
I am almost convinced the original question is related to negative feedback . To be told I am wrong about this makes me smile. No time served audio engineer would ever say that, not to my face who knows me. I suppose on a purely mathamatical level in some abstratc sense it has a very small validity. If you try hard enough you always find the Elephant in the room and there always are Elephants.
I once asked Michael Gerzon what he thought about negative feedback ( Even said it that way, as Michael's use of English was the best I have ever known it wasn't a good start ) . He laughed out very loudly and said he never had. He then went quiet and said this " Had I have thought of it I might have said this. Some amplifers need a lot and some very little ". Then after a pause of some seconds he burst out laughing and said " You can be sure of one thing. Nearly all have the wrong amount". I will tell you something. Michael was the most gifted person anyone will ever meet. His simple statement holds all the truth this world can know and I chalenge anyone to out say what he said. Peope who speak of Michael seldom say about the laughter and pauses. The quieter moments were I would say moments of great kindness as he had made a big effort to get it in understandable terms. I won an arguement with Michael over analogue and digital. When made a musical arguement Michael said he knew exactly what I was saying. Then he smiled and said all of that can be fixed as the numbers look fine. His last point being he could already live with digital errors and these would become less. Analogue errors he saw no easy answer to. If he had started his final digital work by then I don't remember. What I never said to Michael is BBC 13 bit was fine. It wasn't digital I disliked it was and is CD.
I am almost convinced the original question is related to negative feedback . To be told I am wrong about this makes me smile. No time served audio engineer would ever say that, not to my face who knows me. I suppose on a purely mathamatical level in some abstratc sense it has a very small validity. If you try hard enough you always find the Elephant in the room and there always are Elephants.
I once asked Michael Gerzon what he thought about negative feedback ( Even said it that way, as Michael's use of English was the best I have ever known it wasn't a good start ) . He laughed out very loudly and said he never had. He then went quiet and said this " Had I have thought of it I might have said this. Some amplifers need a lot and some very little ". Then after a pause of some seconds he burst out laughing and said " You can be sure of one thing. Nearly all have the wrong amount". I will tell you something. Michael was the most gifted person anyone will ever meet. His simple statement holds all the truth this world can know and I chalenge anyone to out say what he said. Peope who speak of Michael seldom say about the laughter and pauses. The quieter moments were I would say moments of great kindness as he had made a big effort to get it in understandable terms. I won an arguement with Michael over analogue and digital. When made a musical arguement Michael said he knew exactly what I was saying. Then he smiled and said all of that can be fixed as the numbers look fine. His last point being he could already live with digital errors and these would become less. Analogue errors he saw no easy answer to. If he had started his final digital work by then I don't remember. What I never said to Michael is BBC 13 bit was fine. It wasn't digital I disliked it was and is CD.
A bit OT, but it's BBC FM's birthday, so why not?
I doubt anyone has noticed!
The sad thing is they put the entire BBC research team out to pasture quite recently in the usual "short termism" and "dumbing down the BBC has become a byword for now.
I never met Gerzon, but I know people who have.
His opinions, unacceptable as they often were command tremendous respect to this day.
I imagine he would be stunned and shocked to see what has happened to the BBC today, but there, they allowed Savile & his ilk to roam unchecked for decades...
From what I heard, he didn't understand political correctness, and I'm told his work with the Holywell music room and other intra-uni activities was a learning curve of its own.
(I was in a very different musical world in Oxford in those days.
One of the greatest violinists of the 20th century lived there).
I suppose I've been lucky enough to be mixed up with another of the leading lights of audio, some decades after, but it wasn't in the UK. 🙄
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