Are 60's tape recorders an important part of the "60's sound?

[Welsh Anorak]

Hi
And I think that last comment of Tim's has exactly hit the nail on the head - just transpose it to sixties recorded music.
Glyn

[brenellic2000]

Getting back to the original question about 60s 'analogue' sound....

Can I ask a 'daft question'?

I can understand the need to improve signal to noise ratios on tape, but if the best of the 1960s studio ribbon microphones had a response range of up to 16,000Hz (I believe AKG claimed 20,000Hz on one model) and most studio sessions used accoustic instruments with microphones placed close by - and that about the only directly connected 1960s electric instrument was a Fender guitar - clearly, as microphones can't record air-borne harmonics beyond their capability - (ie. beyond say 16,000Hz), why was there a need for tape deck heads/pre-amp specifications to record harmonics beyond 18,000Hz?

Was it purely for "electric guitars" or for scientific/instrument recording outside of the music spectrum? Ipso facto, a qood quality 'hi-fi' domestic tape recorder of the 1960s is perfectly 'adequate' to satisfy the recreation of that 60's sound?

Barry

[neon indicator]

16kHz or 15kHz or whatever is the 3dB point.
The attenuation above the -3dB for most microphone is gradual.

Tape frequency response is related to smallest size "magnet" you can create on tape. If the tape is faster, you can do more "magnets" ion same time.

If the head gap is smaller then you can make shorter magnets for a given speed. This is why video uses a transverse head or a helical wrap on a spinning drum.

Unlike the microphone which is a 1st or 2nd order mechanical filter, above a certain frequency you can't create reversed "magnets" at all on the tape, due to speed and head gap. There are all kinds of problems with narrower head gap.

So unlike many other audio equipment (Microphone, Loudspeaker, Amplifier, phonograph, gramaphone and transformers), the frequency response drops like a cliff at the "extinction frequency" defined by head gap and tape speed. Basically double tape speed practically doubles the upper frequency response limit.

This very sharp "knee" to the frequency response wants to be above the 3dB limit of the rest of the system. It's no surprise that cheap cassette players could barely manage 10kHz.(1 &7/8th ips). With same head gap you would get nearly 30kHz at 7.5" ips.

Older machines with wider head gap (3.5 times wider!) used 15ips (38cm ps) to get 16kHz.

[neon indicator]

Another thought.

An amplifier overdriven clips quite nasty. The tape magnetic response has two problems:
1) At low signal levels it doesn't magnetise properly and has hysteresis. This is solved by super-imposing an ultrasonic signal on the audio, the bias. A stronger version of this is used with a wider gap head to erase the tape as it will be then above the extinction frequency. Without bias it sounds like cross-over distortion

2) At higher levels the transfer curve is less sensitive. This is a gentle compression that in electronics would need a specially selected array of diodes or valves (easily done in digital signals by a lookup table).

So by manipulating record signal level and bias level you can adjust low level distortion, SNR/dynamic range and have a variable degree of smooth compression without harsh clipping at higher signal levels as the magnet material starts to "saturate".

Of course "proper" studio engineers and BBC etc adjusted bias and signal levels so that the playback sounded identical to the live signal

Here is some background
http://www.soundonsound.com/sos/1997...ganalogue.html

The size of the gap in the replay head has a critical effect at high audio frequencies. When the recorded signal on the tape has a wavelength equal to the width of the head gap, there will be no net magnetic flux, so the electrical output from the head will be zero. This is called the extinction frequency, and the frequency response of the head falls rapidly as the extinction frequency is approached (see Figure 2). Clearly it's desirable to design the head such that the extinction frequency is well above the highest required audio frequency, so a very narrow head gap is used. While this was difficult to achieve in early tape machines, modern engineering has allowed the sub-micron sized gap. [edit: hence the 15ips instead of 1&7/8ths)]

Note that if a lower tape speed is used, the recorded wavelengths will be correspondingly shorter, so the extinction frequency will fall, potentially reducing the frequency range on replay -- a common problem with cheaper cassette machines, for example. The dichotomy between the head gap requirements for recording and replay functions also explains the preference for three separate heads in professional machines!

An interesting point related to the reduction in replay head gap sizes over recent years is that modern machines can extract a far better frequency response from old archive tapes than was ever possible at the time of their recording. As the recording process is largely independent of the record head's construction, recordings made in the late '50s and early '60s are frequently found to be of extremely good technical quality when replayed on modern machines. The quality limitations of early tape recorders were generally related to their large-gap replay heads and antiquated amplifier circuitry; the recordings themselves were often to a far higher standard than could be replayed at the time!

[veffreak]

Thanks for the very informative posts and explanations - i feel a bit less and more retarded than before - all at once
Micheal, this is what i mean and what i'm after - Dark side of the moon is id say in some ways a "hi-fi" record - when listening it on good equipment you get a wonderfully detailed "stage" and can identify each instruments and effects position. The cash-machine sound on money can be heard somewhere on the left BEHIND you even on a stereo setup - it's very spacial. And this is one of the best signs for a top-notch recording, post processing and what not. There's no such example in any of the better 60's recordings to my knowledge at least.
So i'm still wondering what is it that gives the 60's recordings their "olschoolness"? - a high end roll off and some loss of some details in the upper mid range, as a few examples? i always wished i could hear Hendrix on a recording doen with the 70's equipment that Pink Floyd used , but also find it interesting how one could approach the "lo-fi"ness of the 60's recordings. What i understand from the technical explanations of what 60's recorders were capable of, it seems like it might not be the place to look. Getting a flat response up to 16khz should make sound anything pretty much without any loss, except for dogs and EJ Also mikes seem to be up to the task then too. Is it what has been done in post-processing or something else?

veffreak

[neon indicator]

I'd not agree about 60's being "lo-fi"

Certain labels and genres had particular styles. Some of it was playing, some choice of amplifiers and microphones and also maybe various analogue effects and over driving. I can definitely hear some distinctive spring line reverbs and fuzz boxes (easy to physically make and easy to digitally simulate).

There is a huge variation between Peter Paul & Mary, Beatles, Shadows + Cliff Richard, Mowtown, Simon & Garfunkel's Wednesday* Morning 3AM, Elvis Wooden Heart, Monkees, Fortunes, Johnny Cash, The Seekers, Beach boys, Tremoloes, Hollies, Nancy Sinatra, Gene Pitney, Roy Orbison or Sandy Posey.

I've personally never been that fussed on Jimi Hendrix (Eric Clapton is not to bad on the guitar) or Pink Floyd. (I only bought Relics, but my friends subjected me to Dark side of the moon).

(* The second hand LP I got in the 1970s likely the 1966 re-release. I now have CD and it sounds similar)

[Antlong]

Hello all,

I don't think any time considered itself to be "lo-fi!" Even in clockwork gramophone days some people strived as best they could for best reproduction!

My Dad's friend Johnny Morgan in the 1950s went to considerable lengths to increase the quality of his record and tape equipment - my first tape recorder was his Truvox, it played 3 3/4ips and 7 1/2ips, top track but right-to-left which was a bit of a pain when I upgraded... He built himself at least one ultra-linear Mullard 5-10 I'm sure.

Regards Ant

[dave walsh]

I like that tech rating you are now after VF ie "old schoolness". Although, from using the term "grail" it appeared at first, that you were after the best technical spec ie the A77 or a Nagra [as used to get Dylan at the Free Trade Hall 66] it actually seems to be a "sound" [obviously]. I think the Floyd album is a bit of a "pink" herring as it was all multitrack and flared trousers by then and "HI-FI" ambitions! It's good but too slick-like stereo demo records from earlier times. Even the A77 Mk1 seems to be very late in the day [68]. Most of the stuff you admire will have been done on "inferior?" relatively antique gear but of quality and driven [overdriven] by people who were prepared to experiment. I think it's a combination of technology and enviroment creating something extraordinary up to circa 1969. Use of the the gear was re-invented in a way. Things were done that shouldn't have happened in theory. I doubt it would have been the same with seventies new kit-just like the trendy new studios sounded flat. Sixties stuff had a Jukebox sound without needing a robot in the corner to play it and produced singles that sprang out through your post war valve woodie [9khz tops/best Radiogram/TV or tinny Tranny like a physical shock. Quite an achievement really!

Dave W

[P.Pilcher]

In the mid 1960's I was at university and like some of my fellow electronics undergraduates a "Hi Fi nut." I had my Goodmans Maxim speakers, my Wireless World transistor 10W per channel amplifier, my Goldring-Lenco turntable, Shure M55E in an SME arm and my trusty Brenell STB2 tape unit. About 20 years ago I could eventually afford to to upgrade to my lovely Quad electrostatic speakers, amplifier and cassette, DAT and CD players. Through this system the Brenell sounds even better when it plays some of the recordings I made in the 60's on it.
In 1966 the legendary technical director of Pye Records, Bob Auger visited my University to record a student operatic society performance for us and to give us electronic lot a lecture on professional recording techniques.
Apparently, we were informed, the big problem with the recording of classical music was the background hiss produced by the master tape. (Bob demonstrated an Ampex machine using .25" two track tape.) The problem was that this hiss was so bad that professional machines had to use 32" per second to minimise it - the first movement of a symphony taking eight 15" NAB spools of tape! Of course we were coming to the end of the period when just about every classical work was being re-recorded due to the introduction of Stereo. At this time, a new tape type was becoming available to professional users - Scotch Dynarange. It needed a slightly higher bias level to make good recordings on it but cut the noise level significantly. I still have some discs purchased at the time on which some of the recordings were made pre-dynarange and others were post dynarange and my kit could easily show up the difference! (A good anti-hiss treatment of the digital copies of these pre-dynarange recordings can work wonders!)
A day in the company of this man as he made his recording of our opera taught me much of the technique of a professional recording engineer, knowledge which I have used ever since. For his recording he used Beyer large, dual diaphragm capacitor units which could be switched to cardioid, omni and figure of eight responses. Although these cost well over £1000 a pop (yes - in the 1960's) I was delighted to discover, about 12 years ago that similar units could be acquired for a couple of hundred quid. The standard of my own live recordings (on modern digital kit) went through the roof when I acquired some of these. This type of capacitor unit has set the standard for recording studio work ever since they were developed, so are certainly capable of producing the "authentic 60's sound" if you can define what that is. What it is worth mentioning is the dismal expression on Bob's face when he was lecturing us on the recording of pop groups. He explained, mournfully that he was obliged to place one of his £1000+ microphones close to the tatty loudspeakers of each of the overloaded and heavily distorting guitar amps, and another close to the drum kit. It is THIS which produced the "1960's sound!"
Of course, the other problem was the recording level of the record cut. In those days the average teenager had a one valve amplified Dansette record player. Naturally the maximum possible sound level was required and this could only be achieved by getting the ceramic (or piezeo electric) cartridge to generate a huge signal - hence a very large amplitude cut of the vinyl disc was needed. Each recording company was always checking on the products of their competitors, because if their latest disc did not sound as loud (or louder) than their competitors then market share could be affected!
Conversations about "Hey have you tried so-and-so's latest E.P? They are at least 1.5 dB up on our last release - we'll have to do something!" Were rife at the time. It was of course a careful balancing act as to what a simple cheap ceramic cartridge could track without excessive distortion. Sometimes they jumped right out of the grove - without a full box of Swan Vestas resting on the pickup arm.
My Shure M55E never got anywhere near such records!

A year later, Bob returned to deliver another lecture - for some reason he liked us - or was it the Snowdonia scenery where we were located? This time, using the same equipment as before he gave us a startling demonstration of his latest toy: the Dolby A noise reduction system. He told us that his company could only afford a couple of these units - but Decca had acquired ten! I hate to think what they cost.

P.P.

[TIMTAPE]

Originally Posted by veffreak

Dark side of the moon is id say in some ways a "hi-fi" record - when listening it on good equipment you get a wonderfully detailed "stage" and can identify each instruments and effects position. The cash-machine sound on money can be heard somewhere on the left BEHIND you even on a stereo setup - it's very spacial. .... veffreak

I think Pink Floyd and similar bands used pretty fancy arrangements and production techniques for their time, hence the later Punk rock revolt some years later where much cruder production was the go.

The Beatles only had limited tape tracks which meant limited ability to "pan" each track (voice, instrument) into different points in a stereo field from left to right. Many tracks meant you had no such limitations. Perhaps what you are hearing between 60's and 70's records is partly this more natural and sophisticated stereo stage with the latter, courtesy of more tape tracks.

Still, even with full use of the stereo field, it's not possible to make a sound appear to come from BEHIND you. Way off to the left or right, yes, but not behind. Stereo cant do that, whereas surround sound can. I think you just imagine it is coming from behind.

Tim

[veffreak]

Yes, that may have been exaggerated a bit - but very very very very far to the left would be precise
Might be that what i'm after isn't so much in the equipment, but the "philosophy" of the engineers behind the sounds and the corresponding trends of different eras.

Veffreak

[TIMTAPE]

Originally Posted by brenellic2000

..., why was there a need for tape deck heads/pre-amp specifications to record harmonics beyond 18,000Hz? ...


Barry

Barry,
I'll add my take on your question.

The real limitation on frequency response of microphones, amps, recorders etc is normally that humans cant hear much above about 15khz anyway and so it could be an expensive and pointless exercise to design gear to cover those frequencies much above that.

But with tapes the situation is not quite straightforward. You could design a machine and tape that was essentially flat out to 15khz but the tape noise was worse at the higher frequencies than it was at a mid or low frequency , hence the problem of "tape hiss".

Failing better tapes, you could just double the tape speed. This meant lower hiss. As a sort of unexpected bonus, the high frequency response got higher too.
But also, professional machines used high tape speeds for better, more precise editing performance. Using the slower tape speed you might get the same frequency response (and deal with noise using Dolby) but editing would be more sloppy.

Actually machines running at 15ips or higher had potentially an upper limit way beyond 15khz, but of course with audio there was no practical use for it. It was just a by product of high tape speeds used professionally.

This explains why cassette tapes running at an eighth of the tape speed of pro reel to reel machines could have about the same upper frequency limit, say 15khz. In fact the pro machine's much faster speed could potentially record a tone way above 15khz but there was no point in designing it like that for audio applications. There are other complications here but I wont go into them now.

Interestingly though, these days in the world of professional tape restoration this phenomenon is sometimes exploited to help restore poorly recorded reel to reel recordings. A professional recorder might have had some wow and flutter (speed instability) which was not noticed by the techs before the machine was used to make an important live recording. As a result the recording when played back would have sounded sub standard and possibly unuseable.
These days a technique has been developed which can sometimes deal with this problem. As mentioned, high speed reel to reel machines could often record frequencies way above audibility. Sometimes this was so high that even the supersonic bias tone was actually recorded on the tape and years later can be played back via special equipment.
Being a stable tone, it can sometimes be used as a speed reference by which to digitally realign and smooth out the speed fluctuations in the recording. But that's an aside.

Hope the explanation helps. Tim

[Michael Maurice]

Originally Posted by brenellic2000

..., why was there a need for tape deck heads/pre-amp specifications to record harmonics beyond 18,000Hz? ...


Barry

When we talk about machines with the capability of recording beyond 18KHz, we're talking about recording sine waves for testing purposes, but of course we dont listen to sine waves.

Music is very very complex and what makes an instrument unique is its harmonics.

Take for example a snare drum, or perhaps a cymbal. If you were to analyse the sound you'll find that it made up of harmonics that go well above 18K, if you limit the frequency response, you'll still get the sound of the drum or the cymbal, but it will have lost something, humans cant generally hear above 16KHz but those frequencies still play a very important part.

On a rather different subject, I noticed that some people are discussing the merits of different bands / pop groups from that era, this is somewhat OT considering the thread is about tape recorders. Could you kindly please stay on topic.

[brenellic2000]

Thanks Tim, Maurice and Neon Indicator,

Sorry, I know the theory behind head-gap width and frequency response...

... but what I was trying to get at is that: if the microphone itself was only sensitive up to 16,000Hz and it was only recording acoustic sound waves (as opposed to plugged in Fenders and amplifiers) then surely it could only 'pass' up to 16,000Hz to the tape heads, which could only record that signal onto tape - ie: surely it can't record harmonics beyond 16,000Hz limit of mike onto the tape? So...

... does the output amplifier and the speaker cone therefore 'add' harmonics above and below the microphone's capabilities - ie: do these extreme harmonics actually exist on the tape?

I'll give you an example: a 'good, well recorded tape' replayed on my 1955 Brenell Mk.2 deck (Brenell heads, bog standard Mullard type valve amp, 8" Goodmans speaker in an Elpico Impessario wooden acoustic cabinet) sounds infinitely better than when replayed on a later Brenell Mk.6 with 'techincally superior' heads, superior Papst motors and transistor amp!

So, is the "60s sound" more to with the loudspeaker than the technical aspects of a microphone's response, and signal to noise ratio - ie: the sound engineer recorded to the limits and capabilties of late 50s/60s audio replay equipment and speakers?

Barry

[dave walsh]

Interesting what you say about the LS contibution during recording "adding value" Barry. VF talks about a philosophy. This is what I was getting at [I think]. Seems more relevant than the individual specs of the equipment to me. I believe some people did mono playback through a small domestic speaker, as well as the Studio Monitors, to check that the "punch" would still be there.

During a recent Bank Holiday I happened to hear the 40 Years of Radio One tribute on various small radios as I moved around the house. The sixties segment sounded so different [in mono] that it really caught my attention and I checked it on the big system as well. It's all subjective but it had me wondering what the source was and was something different in the studio that day? Things seemed to really stand out on [mono portables] more than usual during that program and one featuring M Jagger that followed. Maybe that's the sound. Maybe it's just me.

The added harmonics you mention-would these be 180 out of phase?
I have tried "Quad" vinyl by putting two extra speakers across the output
[in series +L to +R and it does seem to recover reflected sound. During Surf's Up you can hear water behind you [honest] but it's a seventies record and needs 4 speakers not one. Not tried it with a tape though.

[dseymo1]

Dark side of the moon is id say in some ways a "hi-fi" record

Yes, but it was also a hi-fi performance!
I saw Floyd play DSOTM at Knebworth*, and even at a venue of that size, the live sound quality was way in advance of what one usually heard. It helped that they owned one of the largest and most advanced PA rigs of the day (quadraphonic, at that!), which was often hired out in sections to other bands.
The point of this is, how do those 60s recordings compare with the live sound of the artists? I suspect that in many cases, we hear a clean(ish) recording of a live sound 'with character' - which is really just re-stating that it's a production decision, even if one forced on some performers of the time by financial and other circumstances.
There's a parallel in classical recordings from different eras - they often have an overall sound which is distinct and somewhat generic for their age, and very different from modern performances, but this is largely a reflection of the tastes of the audiences and conductors of the time - the instruments haven't changed, and some of the old recordings are remarkably good by any standards.
*Ironically, in a way, their stage set featured a large bank of running ReVoxes - whether these were actually involved in producing the backing tracks, or were just for show, I'm not sure.

[veffreak]

brenellic2000, i think you described much better than i did exactly what i was thinking about when dropping the word "philosophy" of the engineers, which, of course, includes an awful amount of things, among them they also have to bear in mind on what the nedproduct is being listened to and this again involves the question to approach the higher or lower end playback machines as a priority. While the lower end, of course, is the majority (in any era i suppose). And Dave gave a nice example to that.
I have to rethink the whole thing, as the points that were noted here are very interesting and steer my considerations in other directions.

Thank you very much for the very helpful input guys - i was really surprised by the avalanche of great posts!

All the best,

veffreak

[brenellic2000]

In a nutshell, the 50s/60s was an acoustic or live sound - of both instruments and the ambience in the recording hall. The best sounding recorded session, out of say 10 tiring sessions, was then pressed as a record - to be played back on the trannie or Garrard 301/Quad/Tannoy in the cluttered lounge, with is herring-bone floors and scattered carpets, or the school theatre auditorium.

Any well set-up tape-deck which could produce near perfect A-B comparison was thus surely a true "hi-fi" deck.

The 70s introduced a revolution through home-studio multi-channel decks, mixers, track to track transfers, sel-synch... graphic equalisers... ad nausem, often of individually recorded instruments in anechoic chambers, all brought together to ceate an artificially perfect sound that the musician/songwriter/mixer was after - often impossible to recreate live on stage! Today, we have artifically created/edited digital recordings which can lack natural ambience.

"Fidelity" is truthfulness - so 60s recording was surely 'hi-fidelity', whereas 70s/modern digital is not hi-fi at all, but "artistic noise"?

I rest my case, M'Lud!! and will prompty duck my streamlined bald head below the parapet!

Barry

[P.Pilcher]

Brenellic 2000: your mention of the acoustics of the recording environment has reminded me of another of Bob Auger's stories: Apparently, we were told, the place with the best acoustic for recording symphony orchestras at the time was Walthamstow Town Hall. All the recording companies had it booked for months ahead. The hall itself was usually set up with sufficient chairs for two orchestras to be recorded each day; one in the morning and the other in the afternoon. This facilitated a quick change over when time was tight. Apparently, Bob was recording there one morning and just managed to finish in time. As soon as his orchestra was released, the members of the afternoon's orchestra hurried in to take their places and set up their instruments in the set of chairs facing in the opposite direction. Except one player. He promptly stood up and walked over to a chair on the other side of the hall as he was a member of both orchestras and doubtless received double fees for a long day's work!

I bet the Musician's Union never got to hear of it.

P.P.

[brenellic2000]

What I imagine would have truly upset the Union was when the BBC used multiple images of Charlie Drake playing different instruments to make up one orchestra in the BBC TV's 'Our World' broadcast - late 1960s?

Barry