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A tribute to a fabulous recording - Benjamin Britten's 'Peter Grimes'

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  • A tribute to a fabulous recording - Benjamin Britten's 'Peter Grimes'


    I've mentioned a few times this wonderful and pioneering stereophonic recording from 1958, recorded in the second year of the stereophonic era. Even if you know nothing about the format of opera, or don't think you like opera (I'm not a great fan of opera myself) this is the one to have. The performance is conducted by the composer and the recording atmosphere is simply fabulous. These early Decca recordings hooked me on audio in my teens - the first I bought was the 1969 Billy Bud. I wanted to create speakers that would put me right there in the recording venue and make those voices sound as if they really were in front of me, in my listening room. So I'm looking forward to taking you back half a century to north London to the performance conducted by the composer himself. It is absolutely certain that if the same cast, orchestra and composer could be assembled today in the same hall, probably using the same microphones, modern digital recording would offer a technically superior sound. If you know the recording as well as I do, you'll be all too aware of its occasional technical blemishes. Nevertheless, it is what it is and the atmosphere forgives the limitation of the 50s technology. Perhaps we can look at those little foibles later.

    I mentioned recently that Decca records - specifically producer John Culshaw - consciously set about using the possibilities of the then novel idea of the stereophonic L-R width to create on playback at home a really absorbing experience. That was in stark contrast to stereo demonstration disks of the era with their blatant L-R ping-pong effects. We'll cover them another time. We can also hear that by 1961 and Noah's Flood just three years later - there had been a significant improvement in recording quality.

    About twenty years ago when Decca had their analogue tape archive in North London, I visited them and specifically asked to see the original 10.5" Peter Grimes NAB tape reels. We wandered along what seemed like mile after mile of archived tapes all neatly arranged on shelves and eventually found them. I just had to hold one. At the time the only way of editing was to take a razor blade to the master tape (or a second or later generation of it) and once the cut was made, it was permanent. If I recall correctly, there were notes on the box mentioning that there were indeed numerous edits and that some of them, held together with by-then thirty year old sticky tape were very fragile indeed. So the master tape itself, believed to be first generation had been physically spliced with great skill within weeks of the recording. What I had in my hand was a time capsule of a recording venue from the very earliest days of stereo. Many of those involved are no longer alive, so this is my long overdue tribute to them*. (Tape editing and digitisation is another story for another time).

    The original tape to digital transfer was made in 1985, and it wasn't my friend who did that one - but it surely would have been on a Studer A80. I don't recall what digital format it was transferred to: Decca had pioneered the use of digital audio to videotape but having been taken over, probably fell into line with Philips corporation-wide policies and procedures. It really doesn't matter - the fact is the old tapes were transferred to digital before they faded away and we lost this beautiful performance.

    This week I found that Amazon were offering a '96kHz, 24 bit' version of Grimes which has arrived. On a quick listen, I can't hear any difference between than and my original 44kHz, 16 bit version, nor would I expect to: the limiting factor by far is the analogue tapes from half a century ago. The twin CD package doesn't include the libretto, so if you are interested in buying, I'd strongly recommend the original full price if still available just for the libretto. What I'd rather have had for the money is the skilful use of modern digital noise reduction to remove one or two noise artefacts which, when you know the recording well, are audible. They are most likely to be the result of tape storage issues: you have to nurse old analogue tapes which by their very nature, start to self erase from the second they are recorded.

    So that sets the scene. Now to have a look at the layout of the recording stage on the next post ...

    * I've just remembered that I used Peter Grimes as a demo piece at the old Penta/Ramada hi-fi show in London many years ago - probably mid 90s. One member of the audience came over to me and said that he'd actually been present at the recording thirty five years previously and the whole experience was so emotive that he just hadn't been able to bring himself to re-live it on record. We were both lost for words. He said some very kind things about the sound (I think it was either C7ES2s or HL5s) and on he went. I should have asked for his name.
    Alan A. Shaw
    Designer, owner
    Harbeth Audio UK

  • #2
    Trying out the Britten opera CDs

    I bought the 24/96 remastered CD version from Amazon after reading on the HUG how impressed you are with this recording Alan. I also listened to the sound clips of it on the HUG.

    I have it here but have not got round to listening to it yet. Thanks for the reminder.

    All this 24/96 remastering lark seems a bit pointless to me. They do not put it out as a DVD-A disc, so what is the point?

    Anyway, I will give it a listen and also look for the Britten - Noyes Flud you mentioned too. After I finish the Grateful Dead album I am currently listening to that is!


    • #3
      The recording set-up in an ordinary public hall ... London 1958

      London has several well known hall, the most famous being the Royal Albert Hall. But rival record companies Decca and EMI identified far less grand halls which, despite appearances, had excellent acoustics. The late Decca producer John Culshaw wrote in his autobiography about the Kingsway Hall ....

      (to follow)

      and the history of the Kingsway Hall can be found here. As you can see from the photographs here there is absolutely no clue from the outside that the acoustics inside were considered to be one of the very finest in the world. The hall was actually owned by a Christian organisation, and rented out as needed. Another famous hall was the utilitarian Barking Assembly hall - more on that another time.

      "Despite the drawbacks, Kingsway became the most sought-after recording venue for orchestral music in England because of its central location and excellent acoustics, particularly in the 1950s and 1960s when companies were converting from monaural to stereophonic recordings. The London Symphony Orchestra alone made 421 recordings there between 1926-1983; the London Philharmonic Orchestra made 280 recordings there, including its very first sessions (with Malcolm Sargent conducting choral favourites)."

      So, the appearance of the hall and its acoustics can be complete opposites. Decca made their first stereo test recordings in 1955 at Kingsway, but there were other London halls available to hire: Walthamstow Town Hall (also here)was where Grimes was recorded. Another good hall is the Barking Assembly Hall. There is no automatic corrolation between the appearance of the hall and its acoustics: sometimes, by chance, the acoustics 'just work'.

      Although e take it for granted now that stereo offers a life-like experience, in the 50s even amongst record company executives there was almost total apathy - even hostility - to this new fangled invention. The money men at Decca, according to Culshaw, with exceedingly hostile to the stereo concept. The public wouldn't appreciate it, didn't need it and wouldn't pay for it. It would be more complex to record and stamp LPs. A few subversive engineer/producers could see the potential. What was needed was showcase performances, planned down the the smallest detail for the best possible all-embracing stereo effect. That literally meant dividing the stage up into a clearly marked grid, going through the score bar by bar and asking the singers to move, left right, front back. The intention was that this would be captured to tape. And it was.

      Attached first picture of the arrangement at the Walthamstow Town Hall. You can see the composer/conductor Benjamin Britten on the podium, bottom left; the orchestra arranged in front of the stage with the usual left to right arrangement of instruments; the stage, raised about 1.5m above the orchestra with clear line of sight with the conductor; singers arranged across the stage left to right; the chorus far right and to the back. Note how the orchestra is facing the conductor, and for most musicians the singing on the stage is either fully or partially behind them. It's the conductor's skill that keep the entire stage and orchestra performing as one. We'll look at the microphones later.

      Another picture of the stage layout from above, clearly showing the grid matrix. If you look carefully between the radials 7 and 8 you can see producer Erik Smith (glasses, sleeveless jumper, black tie in grid sector 7D) and engineer Kenneth Wilkinson (glasses, toe touching 8B) and performers deciding upon exactly where to position themselves for the intended stereo perspective. This 1958 recording was planned in minute detail.

      Of Kenneth Wilkinson who died in 2004 it was said:

      "Everyone loved and respected Wilkie, but during a session he could be exacting when it came to small details. He would prowl the recording stage with a cigarette half-ash between his lips, making minute adjustments in the mike set-up and in the orchestral seating. Seating arrangement was really one of the keys to Wilkie's approach and he would spend a great deal of time making sure that everyone was located just where he wanted them to be, in order for the mikes to reflect the proper balances. Of course, most musicians had a natural tendency to bend toward the conductor as they played. If such movement became excessive, Wilkie would shoot out onto the stage and chew the erring musician out before reseating him properly. He wanted the musicians to stay exactly where he had put them. He was the steadiest of engineers, the most painstaking and the most imaginative. In all of his sessions, he never did the same thing twice, making small adjustments in mike placement and balances to accord with his sense of the sonic requirements of the piece being played."

      "The most remarkable sonic aspect of a Wilkinson orchestral recording is its rich balance, which gives full measure to the bottom octaves, and a palpable sense of the superior acoustics of the venues he favored, among them London's Walthamstow Assembly Hall and The Kingsway Hall of revered memory"

      Attached Files
      Alan A. Shaw
      Designer, owner
      Harbeth Audio UK


      • #4
        Some of my favorite orchestral recordings are from Kingsway Hall, particularly those engineered by Kenneth Wilkinson. As I recall, you can actually hear the rumble of the subway train (the Tube, as you locals call it!) in quieter passages in many of these. In some, you can actually tell the direction of the train!


        • #5
          I had hoped someone would buy this treasured recording. But without the words ...... can they be found on line somewhere?

          P.S. Found them for you here. Strongly recommend that you have them to hand as you listen; it cements the whole performance in your mind then the first time through. I've attached the libretto for you.

          BTW: In both the attached and the libretto with the original Decca CD I think Swallow (Owen Brannigan) doesn't quite sing what is written:

          Bob Boles started shouting.
          There was a scene in the village street from which you were rescued by our landlady?
          Yes. By Auntie.
          We don't call her that here....You then took to abusing a respectable lady.
          (Peter glares.)
          Answer me....You shouted abuse at a certain person?
          See what you think but don't look for variances - just enjoy the performance from long before you were born!
          Attached Files
          Alan A. Shaw
          Designer, owner
          Harbeth Audio UK


          • #6
            Thanks for the Libretto Alan, much appreciated. Will have to listen tomorrow now though, getting a bit late for a whole opera in one go!


            • #7
              Thanks Alan,

              I ordered my CD yesterday. The Libretto is much appreciated.



              • #8
                The microphones used for the recording

                The microphones

                From the start of the stereo era in the late 1950s, the Decca Record Company and its rival EMI shared several recording venues. EMI were manufacturers of recording equipment and Decca weren't, so Decca used EMI tape recorders. Both made their own mixing desks, and both used bought-in microphones. Decca's uniqueness was their arrangement of microphones which they promoted as creating the 'Decca sound' and which they claimed captured a more life-like sound. There is one very significant strategic difference between 'legacy' recordings and modern ones: at the time of Peter Grimes the very latest studio tape recorder technology had only two tracks, left and right. That implied that the recording engineer was obliged to commit to tape the entire performance of orchestra, musicians, sound effects all correctly balanced for level and L-R pan positioning.

                It's hard to imagine now, in the multi-track, multi-take digital recording world, the pressure on the entire team from the conductor downwards to be note perfect, on cue, on pitch, in position and at the correct level. If any one performer was just a fraction out of step and the entire take would have to be abandoned and everyone prepared again. And sometimes the mistake would only become apparent on playback, which dragged-out the whole recording process, and increased costs and stress. The process is difficult enough for recording just an orchestra, but an opera like Peter Grimes is much more complex: there has to be a take-perfect balance between the very different sonic spectra and acoustic power of the orchestra versus the singers. The orchestra must not be allowed to swamp the singers, yet you can't 'turn down' an orchestra - so the recording engineer has to contrive to balance the orchestra against the singers by manipulation of microphones and distances. And, he had to get it all perfect in one two-channel take.

                Modern multi-track recording was conceived as a way to sonically isolate individual musicians (or groups of musicians), and record them to their own track. This allows their performance to be edited or re-recorded long after the other musicians have packed-up and gone home. It reduces recording costs and stress. But it does need a re-thinking of the microphone arrangement. To isolate performers they need their own dedicated microphone(s), brought close to them so that adjacent musicians are drowned-out. And as we found here, the position of the microphone relative to the musician will change the balance of direct and reverberant sound collected by the microphone: close-miking will dry-out the sound and make it harder and less like what we hear in a good seat in the concert hall - close miking will tend towards positioning us in the orchestra, as the conductor would hear.

                We may be able to learn something from close examination of the Walthamstow Town hall stage (pictures attached). Across the front of the stage there are five mics: 1, 3 and 5 are of one (stick) type; 2 and 4 are of another type. Microphone 4 appears to have flatter side which seems to be perpendicular to radial eight. Note that the vocalists music stands are not only positioned L-R in radials 1-8 across the stereo spread, but front to back. Far left one stands in sector 1A (near Sir Peter Pears); on the right side another in 8B. Are these stands randomly placed there or are they positioned to balance the relative vocal power of the individual voices as seen by the stage-front microphones (which have no ability to isolate and treat individual performers)?

                I've also pointed out (yellow arrow on the left) the wind sound effects machine.

                If we step back we can see the microphones covering the orchestra - only two visible marked A & B, suspended on long booms high over the orchestra and seemingly angled downwards. A and B seem to be of similar shape to microphones 2 and 4 covering the stage.

                > (more later after I refresh my memory about what the mic's were ....)
                Attached Files
                Last edited by A.S.; 27-03-2011, 10:56 PM. Reason: Microphones used for Peter Grimes recording
                Alan A. Shaw
                Designer, owner
                Harbeth Audio UK


                • #9
                  Identifying the microphones used

                  There is no technical information in the liner notes accompanying the original LP boxed set (which I have), nor the original Decca three-set CD. But there is a small note in the '96kHz, 24 bit' remaster. The microphones are identified as the Neumann M50 and KM86. This seems believable as these microphones were in use at that time.

                  Working back through my collection of Wireless World magazines I've scanned the 1953 two-part article 'New High-Grade Condenser Microphones'. These articles introduced the then new Neumann M49 microphone which on page 53 fig.13 is revealed with the gauze cover removed. The exposed sound receiving diaphragm element is sitting atop the tube head amp. Fig 11 shows that the pick-up polar pattern can be varied by moving a slide switch. In fact. the M49 uses twin capsules, back to back and the variable pattern is the result of partially or fully turning on or off the back-side capsule. This article was written by Neumann's UK importer, F.W.O. Bauch, and we must assumes that the frequency response graphs are valid for real-world specimens. The frequency response curves for the M49 (page 53, fig. 11) are basically flat for the solid line cardiod-shaped pattern.

                  On page 111 fig. 16/17 we can see the externally identical M50 with cover removed. This single-capsule is unconventionally mounted in a perspex 'gold-ball' which has the remarkable effect which according to fig.16, starts to lift the output starting at about 2.5kHz and slowly increased to plateau some +5dB higher, around 20kHz. That's roughly a doubling of output over three octaves, on axis. As noted on page 111, 'in a diffuse field of sound the frequency response of the microphone is practically flat.' In other words, when the performers are some distance from the mic, even if not exactly on-axis, the sound will not have the sort of high frequency dullness which are characteristics of microphones and loudspeakers off axis. The use of the M50s in a hall with a well controlled, dry reverberation seems to be a very carefully considered choice - that's how it looks to me anyway. A write-up on the M50 here - also here - note that for use in 1958, the M50s must have been M50A or Bs. A close-up of the M49 and M50 capsules attached. Note that M50s frequency response curves are of a different shape in the Wireless World and website links; I've overplotted the WW curves with it's greatly expanded vertical scale with the web site curve above and another curve found here. Despite small differences, all three confirm the generally rising response - see attached png.

                  There is an excellent write-up on the pencil-shaped KM86 (marked as microphones 1, 3 and 5 on the previous on-stage photo) here. Note: this microphone had a variable pick-up pattern which could be selected by a switch at the bottom of the case near the plug: as shown in the stage picture. Also note that although the microphone is tubular, the capsule, the working part that picks-up sound and hidden under the protective mesh grille, is perpendicular to the tube body. This explains why, in the photo, the microphone seems to point almost (but not exactly) vertically upwards. We do not know which polar pattern was selected by the engineer but we can use some logic.

                  If producer Erik Smith or recording engineer Kenneth Wilkinson has wanted to use the KM86s in omnidirectional mode, he's surely have just used M50s all round in positions A, B, 1 ,2, 3, 4 and 5. But that would be an unusual number of non-directional microphones close together and unlikely to give a really good stereo image - and Peter Grimes has a excellent pin-point stereo. If he'd set the KM86s to figure-of-eight pick-up, then they would have collected the sound from the vocalists and the musicians (but not sound to the side) equally loud. But from the layout in the hall, we see that the orchestra is facing away from the stage towards the conductor, so a a fig-of-eight pattern on any of the stage microphones would collect the sound from behind the orchestra - and that would sound very odd indeed. So that really only leaves the selection of cardiod pick-up pattern for the KM86s in positions 1, 3 and 5.

                  Assuming that to be the case the microphones polar patterns covering the stage from left to right are .... cardiod, omni, cardiod, omni, cardiod. Plus, assuming omnidirectional M50s, the contribution of A and B over the orchestra. In total, four omni microphones and three directional cardiod mics. Using the generic computer rendered frequency response curves from this microphone database (although I think it over-states the KM50s boost 3-7kHz) we can now compare the frequency response from the five microphones across the stage - see curves. But we can see from the stage picture that certainly mic 4, an M50 seems to be pointing to the radial 9 (i.e. 45 degrees off the centre line) and we can assume that mic 2 the other M50 is pointing along radial 3. Looking at microphone 5, we can see that it is angled downwards, and line drawn from the internal capsule seems to intersect the floor long the A arc - ditto mics 1 and 3. So the performers will be significantly off of-axis from mics 1, 3 and 5 (and will have less top) but the rising top of mics 2 and 4 and its lesser droop off axis will probably compensate for that and restore the top end balance.

                  So why did Smith and Wilkinson select five microphones to cover the stage? The primary reason must have been to solidify the stereo image. The selection of these particular microphone characteristics must have then defined the absolute left-right width (with the cardiod KM86s) yet provided a weighty, warm, overall 'omni sound' for the vocalists. As you'll have seen from the comparative plot of the omni M50 v. the cardiod KM86, omni mics have a flat, extended, deep bass. Cardiod microphones with their more directional character have a bass roll-off.

                  P.S. I had assumed that there were only two microphones covering the orchestra as that is all I can clearly see in the picture. But subsequent research has revealed this about the fabled 'Decca tree' microphone arrangement ....

                  "In the early 1950s, together with Roy Wallace (1927–2007) and Haddy, he [Kenneth Wilkinson] developed the Decca tree spaced microphone array used for stereo orchestral recordings.<sup id="cite_ref-indy_0-4" class="reference">[1]</sup> Decca began to use this for recordings in May 1954 at Victoria Hall in Geneva, a venue Wilkinson did not record in."

                  More on Wilkinson and the various experimental 'trees' here.

                  If that is so, then it is most likely that in 1958, the Decca tree was in use recording Peter Grimes. In which case there must be at least one more microphone over the orchestra in addition to my indicated A and B main overhead mics.
                  Attached Files
                  Alan A. Shaw
                  Designer, owner
                  Harbeth Audio UK


                  • #10
                    Some high points from Peter Grimes

                    To enjoy this wonderful spectacle you need the full CD, a dark room and no interruptions. But just one of two clips which showcase the recording and performance. It's interesting, but I've spent some time on this project in the past few days (I'd really like to document this for posterity - I don't know why I've not done it before) the more I look at the monochrome pictures taken at the recording and listen to the music, one ceases to see the pictures in flat, 2D black and white. The performers start to take on a dimensionality, become real people just like us, but frozen in time.

                    I've matched the photo below to the exact point in the recording. Auntie, sung by Jean Watson is in sector 5A nearest the camera, Capt. Balstrode sung by James Pease is at 9A, and Keen, sung by Geraint Evans in far right, in 10A.

                    May I take you back fifty three years, to when I was one year old, to a hall in north London?

                    Sir Geraint Evans passed away in 1992, Sir Peter Pears in 1986, Lord Britten in 1976 and James Pease in 1967. Jean Watson's present status is unknown.
                    Attached Files
                    Alan A. Shaw
                    Designer, owner
                    Harbeth Audio UK


                    • #11
                      The TR90 tape recorder

                      At the time of recording Peter Grimes, there was only one choice of 'portable' stereo reel-to-reel studio quality tape recorder available in the UK. Made by Decca's classical recording rivals, EMI, this heavy multi-box unit represented he very pinnacle of recorder technology, the Rolls Royce of recorders. Before the professional German Studer, Revox and AEG-Telefunken reel-to-reel recorders entered the UK market, EMI was the primary supplier to recording and broadcast users. All the early-mid period Beatles recordings were made at EMI's Abbey Road on EMI mono and stereo recorders (the fixed, non-portable version of the TR90), until the creative need for more tracks and more flexibility forced EMI's management to buy the four-track Studer machine.

                      The 'portable' TR90 comprised the motor and drive unit and two or three additional large boxes of tube electronics. Picture of motor unit.

                      You can have look around the TR90 on this excellent site. Note: As the machine shown is for sale, I've preserved this important page as a PDF. Here is a video of the TR90 recording from a CD. Also spooling tape here. And here you can see the multi-box set that combines to make a complete TR90. And here the complete TR90 playing a tape.

                      Here is a great overview of the TR90 (studio, fixed version).

                      It's hard to believe now, over fifty years after these machines were made, that they were really capable of such superb performance, and so well made that they still record and play.

                      P.S. Here is a TR90 in use at a BBC studio relation to the BBC's Northern Dance Orchestra. By the strangest coincidence, this very week I received a very nice letter from the authorised custodian of the BBC NDO's tape archive asking if we could loan him a pair of P3ESRs to allow him start digitising the tapes.
                      Attached Files
                      Alan A. Shaw
                      Designer, owner
                      Harbeth Audio UK


                      • #12

                        some threads before alan wondered whether peter grimes etc are still available.
                        i bought this and others some time ago here in germany online, and they are all still available:

                        let me add that before i sold my complete classical vinyl collection last year (>3.600 records) i owned 1.100 Decca SXLs/Sets and had nearly everything from the first 1955 stereo opera (nozze di figaro / kleiber) in first pressings till the last SXL from the beginning of the 80s. i have to point out that this records in terms of sound quality are unequalled in the scene. and, more important, very often the performers are outstanding too!

                        meanwhile i have lot of them on CD and they often equal the quality of their vinyl veterans - withou those pops caused by use and/or the poor quality of the very first vinyl mixture(s).

                        to my ears the so called "decca tree" was the most important invention in recording technique: very very very natural sound, dynamics and soundstaging.

                        before you ask why i sold the vinyl: when i used vinyl records i cared more for things like tonearms, cartidges, stylus pressure and all that vinyl realated playgrounds - and forgot to listen sometimes. so i made a cut and do not regret it.

                        Last edited by A.S.; 27-03-2011, 07:19 PM. Reason: typing mistake
                        Harbeth M40.1-Naim NAC52-Supercap-NAP 135-CDS2-XPS


                        • #13
                 the way: if you like britten + beautiful music + great recording technique then buy this:

                          i am referring to tracks 1-3 (schubert, arpeggione). give it a listen - this is music from heaven, performed by rostropovich (cello) and b. britten (piano). the first pressing of the vinyl SXL 6426 ("wide band") is often sold > 100 GBP!

                          Harbeth M40.1-Naim NAC52-Supercap-NAP 135-CDS2-XPS


                          • #14
                            The recording tape

                            The last part of this overview is to consider perhaps the most crucial component in the recording process: the analogue magnetic tape that would have been used to record Peter Grimes. Far inferior to the abilities of the microphones to handle the dynamic range of the music between soft and loud, greatly inferior to the recording amplifiers in the tape machine and the mixing desk, the limitation of fidelity was the master tape itself. Of that there is no doubt.

                            Magnetic tape comprises a film of microscopic 'iron filings' (hopefully) glued onto a (hopefully) non-stretch stable plastic film - what could be simpler? In fact, every detail of the materials and glues proved to be critical. Recovering audio from old tapes is a highly specialist business. Many transfer engineers have found to their horror that even stored in controlled environment , on the very first play through after a long retirement the magnetic layer itself can literally drop-off - leaving a pile of ferrite particles and the clear 1/4 inch backing tape. Read more here. Excellent article identifying various storage problems with analogue tape here.

                            Introduced in the late 1940s, 'modern' analogue tape technology reached a performance plateau in the 1950s, had a little development in the 1960s and advance to its ultimate potential in the 70s and 80s. No further technical progress is possible with current materials nor is there a market for it. It was the invention of the Dolby A noise reduction system in 1968 which transformed the potential quality of the relatively primitive tapes of that era. On record, Dolby allowed the tape to be driven harder for the same or less distortion and compression, and greatly reduced overall hiss. But this advance was to come ten years after Grimes - so just how did they achieve such an astonishingly good sound from such basic tape? I don't know. But we can make some intelligent assumptions.

                            What was the tape? Well, as I recall from inspecting the analogue master tape at Decca's archive, it has a light grey or light blue/green colour. I have a feeling that Decca didn't use -perhaps for political reasons - EMI's blank tape. And if I recall, there were two popular studio blank 1/4 inch tapes available at that time: an Amercican Scotch (3M) tape and a BASF tape. You can read the fascinating history of the invention of magnetic recording tape and the difficulties of making it during WW2 in Germany here. To quote ...

                            Starting in 1948, dozens of American companies joined the race to build the best or the cheapest or the largest or the smallest professional and consumer tape recorders. 3M’s “Scotch 111” audio tape brand became the world sales leader.
                            Attached is a data sheet published by calibration tape experts MRL (very friendly people) which makes a comparison between 3M Type 111 and later formulations. The final analogue tape used in the BBC pre-digital switch-over was their 'Type 200', a specification written around BASF SM468 (= Zonal 675). Without being experts on magnetics, we can take some advice from here about the remanence of the various tape formulations. Comparing 1940s 3M 111 with 1980s 468 we can see that the later tape is nearly twice as 'powerful' as a magnet, and the ultimate tapes formulations such as BASF 900 about two and a half times better - a maxima. Note how much thicker the magnetic layer is on the modern tapes - at least 30% thicker. What this means is that the new tapes are likely to give a better signal-to-noise ratio (possibly being half as hissy) and will hold onto that signal longer. So if the tape is archived, it will have faded less over time.

                            The relatively poor remanence of the 111 tape and the implications for poor signal retention and higher hiss make the early Decca recording even more remarkable. Just how did they achieve such a great sound with such primitive tape without obvious hiss in these pre-Dolby days? I wish I knew! But what tools and techniques did they have available?
                            • The tape recorder would have been periodically cleaned and adjusted during the recording session. We know from the Beatles engineer* that he was employed as a trainee junior to perform just that vital role
                            • The producer and recording/balance engineer would have thoroughly studied the entire 1000 page Peter Grimes score before the recording, annotated it and had it to hand during the recording ...
                            • and would have a comprehensive knowledge of the dynamic range of the music, the soft and loud parts bar by bar ...
                            • and engineer Kenneth Wilkinson would manually raise recording level faders when the sound dropped too low and where the (mainly) tape hiss would become too obvious and conversely ...
                            • he would (attempt to) hastily reduce or 'gain ride' the level when the when the music suddenly flared-up to avoid tape overload due to its limited magnetic capabilities

                            In this last skill, they were less successful. Either they simply couldn't turn down the fader(s) fast enough or even if they were to, they were aware that if the loud passages were reduced in level it would rob some of the impact and drama from the music. The sonic effect of bringing up the record levels during a quiet passage may not be noticeable, but ducking the level during a crescendo would be. So what did they do? We can find evidence in Grimes, and other early analogue recordings of the alternative strategy employed: let the magnetic tape itself do the compression of the loud passages, concentrating on manually bringing-up the quiet ones by operating the recording volume controls. Picture of simple 1960s recording-session mixing desk (actually an EMI one) attached.

                            However, running the tape 'hot' and pushing it into magnetic saturation using this approach as a 'magnetic signal compressor' has unwelcome audible consequences:
                            • If you listen closely during loud climaxes you can hear that the sound is 'crushed' ....
                            • that is, you can sense that the level is restricted and that the signal has run out of steam ...
                            • and the bass has becomes indistinct, fluffy, softened because ...
                            • harmonic distortion has increased to perhaps 50% .... and also
                            • accompanying high-energy high frequency sounds (e.g a cymbal) lose definition, sound soft and
                            • as if a top-cut filter has been briefly applied

                            These tape problems are similar to the problems of LP cutting and playback - they are entirely the consequence of trying to fit a wide dynamic real-world signal into a medium which is completely incapable of handling the signal range without severe distortion.

                            And there is one more issue that bedevils the poor recording engineer (and also LP cutting engineer): print through. The magnetism that we encode onto the tape bleeds out into space either side of the tape, both on the oxide side and through the backing film. It's barely measurable, but it's definitely there. As the virgin tape passes from the left reel past the record head and then on to the right reel, it is wound-on. layer stacked on layer. Unfortunately, every one of those magnetic tape layers casts a shadow if its magnetism onto the adjacent layer, and the next layer and the next with decreasing influence. We know that the strength of the magnetic field is proportional to how loud the signal is ... and that means if there is a particularly loud section, the magnetism in that length of tape will be greater, and it will create more of a magnetic print-through than a quiet passage. So when the tape is then re-wound to the left reel and replayed, we will hear a pre or post echo of the loud passage depending on how the tape was stored (tail in or tail out). And of course, now the tape is on the left spool, the print-through is still occurring.

                            Have you ever noticed pre or post echo on playback?

                            In addition, due to the fact the tape is being dragged across the tape heads there are tape to head contact issues. It's simply not possible to keep the tape pressed tightly and exactly perpendicular at all times. So we can hear a strange burbling effect during some high energy passages.

                            All in all it is nothing short of a miracle that despite these huge and serious technical obstacles such a marvellous recording was achieved. The result was far, far better than examination of the sonic chain would ever expect. It proves to me that getting the best from the technology of the day makes memorable recordings - not chasing ever finer recording equipment.

                            *Jeff Emerick 'Here, There and Everywhere' ISBN 978-1-592-40269-4
                            Attached Files
                            Alan A. Shaw
                            Designer, owner
                            Harbeth Audio UK


                            • #15
                              Tape longevity

                              There is one further, truly important, point of significance when it comes to digitizing any recording from the analogue era, and that is the physical condition of the tape and how well it has been preserved.

                              There is a nice tidy article on Wikipedia about the main problem encountered when pulling a twenty+ year old tape out of the vault. Once treated as described, it is wise to assume that you will get one or two passes of the tape before it becomes a pile of brown dust...