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Vintage Tape (Audio), Cassette, Wire and Magnetic Disc Recorders and Players Open-reel tape recorders, cassette recorders, 8-track players etc.

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Old 28th Feb 2015, 4:46 pm   #81
jjl
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Default Re: HOORAY for the continued use of analogue recording techniques

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Analogue recording techniques may have a slight advantage when dealing with quiet passages over raw digital methods. This is by not having the curious intermodulation effect you get when a signal that on its own is weak enough not to even exceed the first digital quantization level suddenly has a slightly stronger signal added (strong enough to be quantized). If you are listening to the result then suddenly the first signal can be heard in addition to the second signal. One way around this rather disconcerting effect can be to 'dither' the input by adding low level analogue noise at about the first quantization level, so that the low level wanted signal's presence can always register.
In practice, all but the lowest quality audio analogue to digital conversion systems will add analogue dither at around 1/2 LSB amplitude to the input signal. Certainly all pro audio converters will do this.

John
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Old 28th Feb 2015, 5:11 pm   #82
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Default Re: HOORAY for the continued use of analogue recording techniques

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My experience of live recording - concerts - so no re-take, taught me that analogue recorders have their work cut out recording pianos. This is because of a short lived transient as the piano hammer hits the strings.
Not just pianos: Xylophones, marimbas and drums and cymbals and and Tubular Bells[1] and other percussion instruments all make the recording engineer's life hell with their ' Suddenly - it's +90dB !!' attack.

[1] Church-bells are, I'm told, rather less of a problem.
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Old 28th Feb 2015, 5:52 pm   #83
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Default Re: HOORAY for the continued use of analogue recording techniques

The more I read the thread originating article [signposted by Andy and linked through by Nick p5*-thanks] the more interesting it is although the main conclusion ie that using vintage equipment is not just a matter of nostalgia or self delusion-doesn't surprise me even though there is clearly a psychological component at work as well. The famous Sun Studio in Memphis is still in working order [as opposed to those described in the article that had to be "new builds"] and has featured in BBC4 programs illustrating vividly that it is a combination of technology, circumstance and the recording enviroment that can produce that particular outcome eg Abbey Road.

We can't be conclusive about analogue/digital but it's what works in the end.
Non-the- less it is interesting to read the technical comments re both modes on here and in the [perhaps spin off] thread "Objective Comparisons of Analogue and Digital Recording Techniques". The white coated expert EMI engineers were horrified at first in the sixties when overloading or "modifying" broke the rules but it changed a lot of things!.

Not so directly related perhaps but I've been listening to an Incredible String Band recording recently [1968 Live On Stage]. They are using a primitive electronic keyboard that would have been easily eclipsed by something cheaper and stable from Dixons [there's nostagia for you] a few years later but it's wavering wobbly sound adds so much to the overall effect.
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Old 28th Feb 2015, 7:29 pm   #84
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Default Re: HOORAY for the continued use of analogue recording techniques

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The white coated expert EMI engineers were horrified at first in the sixties when overloading or "modifying" broke the rules but it changed a lot of things!.
Indeed - this was the time when people finally grasped how to use the entire audio-chain - from performer through mics/instruments to recorder to producer to presser to record-player [or perhaps record-player-to-AM-modulator-to-RF-and-transmit-through-the-ether-then-receive-detect-and-reconstitute-the-audio] as part of the overall 'performance'.

The "White-coated EMI engineers" needed to learn that they were just a part of this chain and should be subservient to the musicians/producers in their search for a particular sound.
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Old 28th Feb 2015, 9:30 pm   #85
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Default Re: HOORAY for the continued use of analogue recording techniques

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Not just pianos: Xylophones, marimbas and drums and cymbals and and Tubular Bells[1] and other percussion instruments all make the recording engineer's life hell with their ' Suddenly - it's +90dB !!' attack
Agreed and it depends on the dynamics of the material being recorded, not just the musical instrument. In the 1980's we recorded live voice to reel to reel analogue tape for Talking Books. Evenly modulated voices could be OK but the more dramatic readers could easily exceed the capacities of the tape. If we lowered the record level to accommodate the loud bursts, the overall tape noise became unacceptably high. In the end, careful compression/limiting was the only way to get a good overall result.

Before digital audio recording was available, recording engineers used either compression/limiting or noise reduction systems like Dolby to help analog tape cope with dynamics. With digital recording such techniques are not needed.
I suspect those who still think analog methods could faithfully capture a dynamic performance unaided, never had to actually do it as a job and deliver acceptable results.
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Old 28th Feb 2015, 10:50 pm   #86
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Default Re: HOORAY for the continued use of analogue recording techniques

Coincidentally Ep 2 " Songs of the South" is on BBC2 [not BBC4 for once] at the moment. There was some interesting vintage footage re Aretha Franklin recording but the Studio Owner was even more impressive with his non predjudcial stance! Overall it did illustrate quite nicely the random factors that often come together in the production of a great piece of music-especially "patches".
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Old 1st Mar 2015, 12:14 pm   #87
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Default Re: HOORAY for the continued use of analogue recording techniques

I have a good collection of Direct Cut discs, (mics, mixing desk, cutting machine) these would have been a nightmare for the cutting engineer, one mistake and the whole thing would have to be cut again, but the end results are staggering at times, drums, pianos, orchestras, vocals everything.

The other thing I have not said is about how analogue holds onto harmonics which are lost on CD etc, I can listen to analogue for hours and be drawn into the music so it becomes a journey, I cannot achieve this with CD, the harmonics on acoustic instruments are lost and a bit like the valve versus transistor debates you get the edge of the note but little if any of decay etc that goes to make up the sound of that instrument, I know our brains are very good at making up for that so that we recognise what instrument it is, but it is not the same and after a while of listening to a CD I am too aware of parts of the sound are missing or just wrong.
Deluded I know I am not, my father was musician by trade (jazz mainly) and I am very used to hearing live bands and orchestras as he played in both, I know when a sound is right and when it isn't, analogue with all its faults brings me music where as digital gives me just sound.

Gary
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Old 1st Mar 2015, 5:34 pm   #88
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Default Re: HOORAY for the continued use of analogue recording techniques

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Coincidentally Ep 2 " Songs of the South" is on BBC2 [not BBC4 for once] at the moment
There was a film/documentary on a while back about Rick Hall and Muscle Shoals, he had a tough early life, twice the man a lot of folks would ever be.

I've still got most of the records they played in the first part of the BBC2 documentary (Songs of The South" all a bit scratched over the years, the first LP I bought was Otis Blue by Otis Redding, when I was a teenager I tried to get a job with Atlantic Records and also Stax to be amongst my musical hero's, just a dreaming I guess, nothing came of it.

Lawrence.
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Old 1st Mar 2015, 10:07 pm   #89
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Default Re: HOORAY for the continued use of analogue recording techniques

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with CD, the harmonics on acoustic instruments are lost and a bit like the valve versus transistor debates you get the edge of the note but little if any of decay etc that goes to make up the sound of that instrument,
Certainly lower quality mp3 is notorious for reducing or removing quiet sounds and instrument "decay". That's the tradeoff in reducing file size.
It's also true that so called denoising can easily remove the "decay" from instruments just as does lower quality mp3. In both cases too the higher harmonics are the first to be lost. Yes this can be very tiring and even exasperating to listen to.

But with a standard CD , the only harmonics lost are supersonics which humans cant hear. With proper dither applied the quiet sounds are progressively masked by the dither noise, just as quiet sounds are progressively masked by analog noise in an analog recording.

Tim

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Old 2nd Mar 2015, 11:00 am   #90
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Default Re: HOORAY for the continued use of analogue recording techniques

If we are considering CDs as part of the reproduction chain in a digital recording environment then we need to be aware of the consequences of the differing sampling rates involved between a CD's 44,100 samples per second rate and a digital recording's 48,000 samples per second (or a multiple thereof). The transfer between the digital recording to the CD requires either interpolation, or (just as likely in the early days of CDs) the selective throwing away of some samples. This process can introduce artifacts.

So it would be interesting to compare a CD of a session made using analogue mixing and recording, with a final A/D conversion at 41,000 sample rate to a CD, with a CD made from a 48,000 (or multiple) sample rate mixing and recording set-up.

I suspect the difference may only be discernable on quality classical music perfomances - but am happy to be proved wrong !
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Old 4th Mar 2015, 1:24 am   #91
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Default Re: HOORAY for the continued use of analogue recording techniques

Digital sample rate conversion for audio is a relatively straightforward process, although always subject to some small error if the higher sample rate is not an "easy" multiple of the lower rate.
When I worked in professional audio in the late '80s, conversion between 44.1 and 48kHz rates at 20 bit or better precision could be performed in real time with software running on commercial DSP devices or in hardware built from a handful of PALs, some RAM and an ALU or two. These days, such processing doesn't raise much of a sweat on a mobile phone CPU, let alone a PC.

There is no compelling reason to use 48kHz or multiples of for a multi-track recording that will ultimately be destined to produce a stereo CD. All of the computer based music recording I've been involved with has used either 44.1kHz or 88.2kHz sample rates and either 16 or 24 bits per sample.

John
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Old 4th Mar 2015, 2:03 am   #92
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Default Re: HOORAY for the continued use of analogue recording techniques

Professional recording or archiving of analogue masters doesn't generally use 44.1 though. Part of the explanation may go back to the early Sony pro kit which used 48, and DAT also used 48. Modern hardware means that there's almost no extra cost in sampling at 96 or 192, though the practical benefits of doing this are highly debatable. Almost nobody will listen to these recordings without them being resampled, usually down to 44.1.
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Old 4th Mar 2015, 5:07 am   #93
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Default Re: HOORAY for the continued use of analogue recording techniques

There is a small but growing band of folks who do download and listen at 192k.

Don't know if it will ever become mainstream, though?

Where do we go from CD ?
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Old 4th Mar 2015, 8:40 am   #94
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Default Re: HOORAY for the continued use of analogue recording techniques

I believe relatively few people are listening directly at 44.1 kilosamples/sec because the majority of digital music devices use high-oversampling delta-sigma single-bit DACs, where a data flow of 16/18/24/etc bits that once was at the word sampling rate is up-sampled to a single-bit word at a much higher multiple of that sampling rate.

This has several benefits:

There is no issue about getting the weightings of multiple bits accurate enough.
The unwanted artefacts and aliases are scaled up to much higher frequencies and so lowpass reconstruction filter on the output can be moved somewhat higher than 20kHz, and can have a less abrupt transition band.
It's cheaper.

There are two issues. Does 44.1 kilosample/sec produce a real impairment in hearable audio quality? and does the very sharp 20kHz filter needed by a true multibit DAC running at 44.1kS/s produce a real impairment in hearable audio quality?

Delta-sigma converters perform scrambling and high-order noise shaping which are not intuitively understandable processes.

Sony have taken up the idea of running several delta sigma DACs with the same audio inputs, and their outputs summed together. These are NOT weighted, so they add simply and there is no issue of weighting errors causing non-linearity and non-monotonicity the trick is that the noise scrambling processes in the multiple channels are deliberately de-correlated. This pushes the noise even further out and can make it more 'smoothly random' for want of a better description. I was involved professionally in this principle, though in fractional-N frequency synthesisers about seventeen years ago. Frac-N synthesisers are delta-sigma machines too, and though weighting isn't an issue, the benefit of pushing their essential noise further out and making it more random is valuable. It turned into US patent 6509800.

Digital signal processing and now computation is now unbelievably cheap, so we routinely throw immense amounts of it at a task if it makes the analogue side of things even a little better or cheaper.

David
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Old 4th Mar 2015, 8:46 am   #95
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Default Re: HOORAY for the continued use of analogue recording techniques

For their first generation of CD players, Philips couldn't get a good 16 bit DAC to work. They were limited to 14 bits, but their DAC was a good bit faster than 44.1kS/s required, so they traded speed for resolution and oversampled it.

This chipset wound up under many brand names of player... Marantz, B&O etc. It certainly got around. My first CD player was a Sony ES one using a rather expensive Burr Brown 16 bit DAC. Its replacement is one of the Sony DACs with multiple unweighted decorrelated bits.

If you come across 'MASH' it's one particular way of implementing the structure of a noise shaper.

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Old 4th Mar 2015, 10:23 am   #96
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Default Re: HOORAY for the continued use of analogue recording techniques

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Professional recording or archiving of analogue masters doesn't generally use 44.1 though. Part of the explanation may go back to the early Sony pro kit which used 48, and DAT also used 48. Modern hardware means that there's almost no extra cost in sampling at 96 or 192, though the practical benefits of doing this are highly debatable. Almost nobody will listen to these recordings without them being resampled, usually down to 44.1.
It's true that 48kHz was the preferred professional sample rate in the '80s. However, by the mid '80s, the then current state of the art Sony PCM3324 and Mitsubishi X-850 digital multitrack recorders supported both 48kHz and 44.1kHz sample rates. I suspect that many recordings made with these machines used 44.1kHz.
Domestic DAT recorders tended to be limited to 48kHz in order to prevent direct digital copying of CDs. Pro and semi-pro DAT machines supported 48kHz and 44.1kHz.

John
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Old 4th Mar 2015, 12:28 pm   #97
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Default Re: HOORAY for the continued use of analogue recording techniques

I suppose listening to the BBC's Radio 3 digital service on Freeview TV may be the closest we get to hearing music digital recorded and distributed at 48 Ksamples/sec (or multiple) when a BBC recorded concert is being replayed.

But I do remember that making a live concert recording at 15 ips produced some recordings with what I can only describe as great 'presence'. Of course, one needs a youth's hearing to fully appreciate that!
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Old 4th Mar 2015, 1:00 pm   #98
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Default Re: HOORAY for the continued use of analogue recording techniques

Unfortunately R3 on Freeview is 192kb MP2, and this will be by far the limiting factor on sound quality rather than very subtle changes caused by the sampling frequency or resampling.
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Old 4th Mar 2015, 1:02 pm   #99
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Ah, thank you for that Paul - In my ignorance I had thought it was a 'direct' sampled feed.
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