back to article Decks and plugs and rock and roll: Tascam CD-A750 cassette and CD combo

The recent El Reg feature on the Compact Cassette's 50th birthday had many a reader commenting on some of the format's former glories. Names mentioned among the dewy-eyed included Aiwa (a favourite in UK studios) and the audiophiles’ choice, Nakamichi, with both producing state-of-the-art recorders with three heads and a lot …


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  1. Anonymous Coward
    Anonymous Coward

    Tascam kit

    Used alot of their kit in studios. Spec is usually good but am I the only one who finds their stuff fiddly?

    In a radio studio environment I used many competing products and the Denon and Sony's were always nice to use.

    Although it was to be said we often ended up with Tascam kit when rivals had given up on formats. Minidisc being one of them. About 9 years ago I wanted to order a Sony and although at that stage not discontinued, couldn't get one for love nor money so ended up with a Tascam. It did the job but wasn't as sleek or sexy as the 1U Sony, the Tascam instead managing the dual combination of being larger yet with smaller buttons.

  2. AndrueC Silver badge
    Thumb Up

    Ah brings back memories of the 80s when I was an audiophile(*). One of the last tape deck reviews I read featured a unit with a cute track following feature. It compared the phase of the left and right channels and somehow used that to adjust the head alignment. I also seem to recall there was one that required you to break off the tabs on the front so that it could pull the tape out and wrap it round a helical head like VCRs do/did.

    (*)Happy days. I had no money do anything with it though. These days I've got the money but have lost the inclination - mainly because the lousy production standards on modern recordings make it pointless.

    1. Lallabalalla

      Buy old records


      1. Lallabalalla

        Re: Buy old records

        Thumbs down for that? You clearly have no appreciation of sound quality. Buy vinyl - japanese pressings - masters - put them on your Rega3/Linn Sonndeck and turn it up - preferably through a Leak amp and a massive pair of old Tannoys.

    2. Gio Ciampa

      " I had no money do anything with it though"

      Most of my friends - being students at the time - funded their kit by investing their student grants in the privatisations of BT et al, then flogging off the shares a week later... (as presumably a lot of others did also)

  3. Justin Stringfellow

    "it’s funny how quickly old habits start to kick in, as I wound back a slightly slack pre-recorded tape with my little finger pressed against the sprocket, without giving it a second thought"

    I don't know whether anyone else found this, but the classic BIC pen is a perfect fit for the spools. For those of us who were unwilling to spend precious battery life rewinding tapes in their personal stereo, you could simply skewer the cassette with the hexagonal pen and whirl it round for a minute or so until you'd manually rewound the tape.

    I don't understand the current compact cassette nostalgia wave. I hated the damn things, I can only assume those who like them never had to really use them back in the day. Thank $deity for digital music players.

    1. MacroRodent


      "I don't know whether anyone else found this, but the classic BIC pen is a perfect fit for the spools. "

      Now that you mention it, I too recall using it for that purpose, mainly because I always had some BICs at hand when a schoolboy.

      (All these C-cassette anniversary articles have give me the itch to go rummage Helsinki fleamarkets to see if I could still find a good deck cheaply, before they become collectibles...)

    2. graeme leggett

      A hexagonal pencil did the job too but you were more likely to find an ancient Bic in the glove compartment (or even the parcel shelf under the dashboard) of the car

    3. Peter Gathercole Silver badge

      @Justin re:"don't understand..."

      As a student, I bought a JVC KD-720 deck to go with my budget Hi-Fi. Now, 35 years later, it is the last original component of my system, and still works pretty well.

      It was at the time the "Best Buy" budget (~£100) cassette desk, and (IMHO) did a thoroughly good job of recording and replaying music. The main problem was that it did not have a 'proper' FeCr setting, and pre-dated metal tapes, so could not use them (the Cr02) setting was also not really calibrated for psudo-chrome tapes like the TDK SA). It also only had a 'normal' tape head (not a Sen-Alloy one), so I was always expecting the head to wear, but even now, it's not too bad (apparently, early generation chrome and metal tapes were very abrasive, I guess that missing these tapes out prolonged the life of my deck).

      Even this budget deck had a wow and flutter of 0.2% DIN, and a frequency response of 40-14000Hz with ferric tapes, and 40-15000Hz on chrome dioxide tapes.

      I nearly always used TDK AD-90 ferric tapes to record, because they were the sweat-spot of the TDK range, providing good frequency balance (although slightly bright), good frequency extension (the brightness extended the upper ranges while minimising tape hiss) at an affordable price. They also used to be about 47 minutes long (useful for both sides of a long album) and very well made with friction reducing embossed teflon sheets either side of the spools. The Audio Society used to buy them by the case-full, and sell them at near cost to the members. TDK SA tapes were better but much more expensive, although I believe that the calibrated tape brand for JVC decks was supposed to be Maxell.

      Anyway, my deck always gave exemplary performance. You could tell it was a tape from the hiss if you listened hard, but otherwise it sounded very good and I had very few tape jams or mangled tape in this deck. The sound of it persuaded several of my friends who had the "cassette tape is no good" attitude to change their mind and invest in a decent deck. It also helped having a reasonable music source to record from (turntable in the day).

      To prevent jams, always wind the tape from end-to-end in a single operation and leave them on the leader before storing them. This prevents 'ridges' which increase the drag, especially on the take-up spool. If the take-up spool cannot be turned by the motor (remember it has a slip clutch so that it can cope with the varying diameter of the spool as the tape is wound on), then the capstan and roller will continue to feed tape in until it loops back on itself, and gets mangled. This was a common problem on C120 cassettes, because the nearly full spool was very heavy.

      If it does look like this is happening, immediately re-wind the tape as best as you can before attempting to eject the tape. If you just eject the tape, you are absolutely guaranteed to break or stretch it, and will end up fishing out short lengths of broken tape forever.

      I still keep iso-propyl alcohol around as a general cleaning fluid after using it for so long to clean the tape heads with cotton buds.

      1. RobHib

        @Peter Gathercole - Re: @Justin re:"don't understand..."

        Bloody hell, see what El Reg has done with this anniversary. They've made the worms, en mass, crawl out of the woodwork from everywhere. I couldn't help it either--the comment about the XLR connectors and balanced inputs was too much to stand and I've gone to 'print' about it hereunder.

        Incidentally, I've a 20 litre drum of iso-propyl alcohol in my shed and I use it for everything except drinking (a hangover from the old days of cleaning both audio and video machines (the 1" and 2" variety). [Duh, sorry about the pun.]

        Spirited away, I've still a coupe of bottles of that truly magic cleaner: 3M's iso-propyl alcohol and freon mixture. It's wonderful stuff and the world's worse off without it despite the ozone hole.


    4. RobHib

      @Justin Stringfellow

      "I don't understand the current compact cassette nostalgia wave. I hated the damn things,"

      Justin, I reckon the nostalgia is simply explained. Even though I still have a Nakamichi 680 ZX, close to the best ever unit ever made, I always treated cassettes as a joke professionally. Even the Naka 680 can't be sensibly compared with a good 1/4" (or their bigger brethren 1/2", 1" multitrack) recorder running a good master tape at 15 ips--that's a no-brainer.

      However, there's four things really going for the cassette that clinches it.

      1. The cassette's ubiquity and cheapness (everyone had a recorder).

      2. Sheer convenience (drop in and push record, 1/4" tape never self-threaded like a good 16mm projector).

      3. Portability, you never needed to take the recorder with you as there was one at the destination--even if you went camping you could the one in the car.

      4. Early on, even by the late 1960s, the cassette had been adapted from a recorder of voice to HiFi and music (let's correctly call it medium Fi). At its best, the cassette was good enough to provide music entertainment for the masses. Audiophiles like me used both: cassettes for taping something off AM radio (convenience) and reel-to-reel and LPs for music.

      Frankly, when the cassette first came out I considered it junk, but it's actually turned out to be a phenomenon. And that's what everyone remembers.

  4. Nick


    After reading this article I just had to go and find a clip of the RX202 in action:

    It might be trying to make a silk purse out of a sow's ear, but what a way to do it!

  5. john loader

    Cassettes still needed

    Nobody ever invented an easy to use small CD player for the blind so my transcription service, whilst producing CDs and MP3s, still uses hundreds of cassettes annually which luckily I can still get. With 6 Teac W600R double decks, a Telex 1:1 and 1:7 high speed copier and a manual cassette eraser in my office nostalgia is a glance away

    1. stu 4

      Re: Cassettes still needed

      yes they have.

      my grandfather is blind and uses it every day. provided by the RNIB.

      primarly for their incredibly extensive range of talking books, it also plays audio CDs and its large buttons and audio feedback make it easy for him to use.

      And it's about the size of a large (you know the big old cheap ones) portable compact disc player .

      1. RobHib

        @stu 4 - Re: Cassettes still needed

        That's new.

        It's a while now, but when my father had difficulty seeing he got one of those cassette players with big chunky buttons for talking books. I always liked it because it was strong and rugged, thus I've always kept an eye out for a combo player like you've described but I've never seen one.

        Similarly, I've been on the lookout for a small AM/FM radio, perhaps a bit bigger than handheld, that also had a slot for a USB memory stick, but I've never seen one. Still reckon there's a market for such a device.

  6. Neil Barnes Silver badge

    Aye, them days is gone...

    It's been a while since the Studer/Revox reel-to-reel was a standard part of every BBC installation, along with a 'just in case' cassette player (Denons were popular).

    But the cassette players were generally used only for playing things the listener/hopeful band might have sent in, or for making legal copies of the transmission. The quality was always considered rubbish by the engineers (and rightly so, but given that it was intended as a dictation machine, not a music player...)

    As Dr Johnson might have said: the wonder is not that it worked so well but that it worked at all!

    1. Pristine Audio

      Re: Aye, them days is gone...

      Studer A710 cassette decks were the standard BBC installation for radio studios, certainly in the main London broadcast centres in the 90s. Studer and Telefunken reel to reel machines were found in studios, but not Revox - these were the "domestic" products (most commonly the PR-99) that radio producers got to play with in their offices, alongside domestic hi-fi equipment (from the usual suspects).

      Personally I prefer the sound of my Nakamichi DR-2 to anything I ever heard from the Studer decks, but they were reliable workhorses, required to make two copies of everything we broadcast for legal back-up and archiving, so the decks in the main studios in Broadcasting House certainly put in a lot of hours.

    2. Anonymous Coward

      Re: Aye, them days is gone...

      The biggest reason cassettes never took off for broadcast use is that are impossible to accurately cue. It is impossible to accuracy or quickly cue them up even compared to reel to reel. You still have all the winding around with open reel but cueing is a doddle.

      You can get excellent quality out of cassette tape with the right media and recorder/player. I picked up a load of metal formulation tapes in the Tandy closing sale. Playing around with these tapes in a good quality Sony recorder, I found I was hard pushed to tell the difference between them and the CD I had just dubbed from. Pity the tapes cost so much and never really took off.

      1. Pristine Audio

        Re: Aye, them days is gone...

        Certainly potential sound quality was better from cassette than it was from the awful cartridges we used to use for jingles and so on - but they could be cued up and were designed for broadcasting, unlike the cassette. Horses for courses - the jingles had ended up largely on MiniDisc by the late 90s; quicker to cue and much better sound quality, but lacking the quick-fire one-jingle-in-a-big-plastic-box appeal of the cart. Steve Wright (in the Afternoon) was a brilliant cart operator!

    3. RobHib

      @Neil Barnes - Re: Aye, them days is gone...

      Yuh forgot to mention Nagras. Now that's a sin.

      Correct about cassettes, they were always considered toys. Nevertheless, there was a time when every recording studio, radio and TV station had at least one 'pro' unit (often many more).

      1. Anonymous Coward
        Anonymous Coward

        Re: @Neil Barnes - Aye, them days is gone...

        One of the biggest uses for cassettes in the studio was to create "ROT's" which stands for "Record On Transmission".

        These were sometimes requirements of companies providing prizes to prove you had given the prize away. They'd include a tape and a SAE with the prize and you'd have to tape the competition being run and send it back.

        Of course nobody ever faked these and kept the prizes for themselves especially not our breakfast jock who took a liking to a Sodastream and decided to keep it.

  7. Paul Westerman
    Thumb Up

    My recommendation for tape transfers

    Get a Philips DCC deck - about £20 on eBay these days. They play cassette tapes as well as DCC, sound pretty good and have a digital output. Much better than those crappy USB gadgets.

  8. Roger Greenwood

    Tape still demanded sometimes

    At many synchronised swimming competitions here in UK, the rules still demand 2 x CDs and a backup cassette tape for the music. No one bothers of course, because no one has a working recorder, but if the CD player fails you may be disqualified.

    1. Eradicate all BB entrants

      Re: Tape still demanded sometimes

      An image of a 50+ year old, full bearded bunch of DB admins as a synchronised swimming team just popped into my head.

      Now make it happen.

  9. Annihilator
    Paris Hilton

    "I was pleased that the CD player lived up to its billing and handled non-CD audio discs without complaint."

    Am I being stupid? What's a "non-CD audio disc"?

    1. A J Stiles

      That would be a CD-ROM disc containing MP3, WAV or OGG files, as opposed to "red book" CD Digital Audio which would be playable even on the earliest CD players.

      Mine's the one with all the various coloured books in the pocket .....

    2. Pristine Audio

      CD data discs, such as those with MP3s on them.

    3. TheOtherHobbes

      A disk with WAV or MP3 files stored as data, without the full Red Book formatting used for audio CDs.

      Most players won't play audio from files. A few will play audio from files as a horrible speaker-exploding ear-destroying digital noise.

    4. Steve Foster


      In this context, CD refers to the Red Book spec that defines the format of the content of an optical disc containing just audio recordings. Subsequent Books (primarily Yellow and Orange) define computer storage on optical media formats.

      So a non-CD audio disc is a CD-R or CD-RW containing audio files (MP3/WMA/AAC/FLA, etc).

      1. Annihilator
        Paris Hilton

        Re: @Annihilator

        Just me though or is that a clunky way of saying it - it's still a CD. A "non-CD-DA disc" might make more sense.

        The funny copyrighted ones weren't allowed to say CD-DA, they were still allowed to say CD though.

        :edit: @Vladimir, exactly what I was thinking :-)

        1. MJI Silver badge

          Re: @Annihilator

          Non CD-DA = nightmare

          My previous DVD player worked well with CD-DA but I got fed up with exchanging non playing CDs, I think I had three copies of one CD (to be returned to supplier), eventually found out - non CD-DA due to some data CD nonsense.

          At least I cost them a few copies!

    5. Anonymous Coward
      Anonymous Coward

      Re: What's a "non-CD audio disc"?

      ... or, I suppose, one of those "copy-protected" disks with deliberate errors to foil simple attempts at ripping, but which cd players just interpolated over. I've got a couple at home; one even claiming to be a proper CD.

      Not that that's the kind of "non-CD audio disc" that was meant :-)

      1. Vladimir Plouzhnikov

        Re: What's a "non-CD audio disc"?

        Strictly speaking, a "non-CD audio disc" may be a MiniDisc, a vinyl LP, DVD-A or any other disc-shaped object with an audio recording on it. ;-)

        I have a suspicion that the author meant to refer to a "non-audio CD" or "non-CDDA disc" or "non-CD-audio disc".

  10. Vladimir Plouzhnikov


    As far as I can recall Dolby C was just two Dolby B stages in sequence and it wasn't that good, actually. Between B and C I would choose B but from a deck at such price I would expect Dolby S.

    1. jason 7

      Re: Dolby

      Yes I always felt Dolby C was awful. Like listening to music with cotton wool in your ears.

      Dolby S however, with decent chrome/metal tapes, proper bias/levels was a revelation. That really worked a treat.

      Too little too late though. About 18 months after I got my Sony Dolby S deck I traded it in for a Sharp portable Mini-disc recorder. Direct toslink copies from my Meridian 506 (then a 507) CD player.

      Now that was fantastic! Even had a six MD changer fitted in the car.

    2. bygjohn

      Re: Dolby

      Actually, the problem with Dolby C was that to work properly it needed the deck to be set up properly.

      I was lucky enough to have a local hi-fi shop run by a man with all the right test gear, who'd do a set up for £25: even a cheap deck on cheap ferric tape was transformed. He later has the boss of Aiwa visit after showing a rep how badly their machines were set up out of the box and convinced him by making a set up sub-£100 deck sound better than an out of the box flagship model. Said boss went back to Japan, tightened up the quality control, and when I bought a posh 3-head Aiwa a couple of years later it didn't need setting up as they were doing a proper job at the factory.

      NB this was when Aiwa were Aiwa, and not just a badge for cheap Sony kit.

      Dolby C on such a machine was waaaaay better than B, and HX (which was some sort of sliding bias thing) helped even more. I never heard S in action, but I think C is much-maligned due to poorly set up hardware.

  11. stu 4


    Don't forget they are still the ONLY form of evidence used for recording taped interviews by Plod too.

    1. Pristine Audio

      Re: Interviews

      Hard to edit, aren't they! Especially when recorded on both sides...

    2. Annihilator

      Re: Interviews

      *Some* Plod constabularies would be more accurate. Most (if not all?) moved to CD or DVD years ago.

    3. Anonymous Coward
      Anonymous Coward

      Re: Interviews

      Out here in the US of A, our local police force use portable voice recorders for field interviews and DVDs and WMV files for little chats down the cop shop. The police department still use cassettes to make copies of 911 calls from the master, though. At work I use an awful Telex tape duplicator connected via USB to make digital copies: the drivers are XP only, and we can't connect the PC to the network because the drivers don't play nice with antivirus and firewall software. I'll be glad when they finally go digital.

      About the deck in the article, I wish I had one of these about 6 or 7 years ago. I lived in the UK but was preparing to emigrate to the USA, and couldn't take the shedload of cassettes I had, so I had to convert them using an ancient Yamaha deck connected to the analogue audio in on the sound card.

  12. uncle sjohie

    Pioneer CT-W606DR

    How about an Pioneer CT-W606DR cassette player with AD/DA converters?

    Maybe one can be found on Ebay?

  13. Michael Strorm Silver badge

    Ion R&D?

    "Who is busy doing R&D on cassette recorders these days? If you’re thinking of Ion Audio, these products are aimed at format transfer convenience rather a serious effort for archivists"

    To be fair, I suspect that most El Reg readers (and certainly those interested enough to be reading this article) know it's unlikely that Ion are doing anything that could be described as "R&D" beyond sticking a USB ADC or digitiser onto a low-end generic mechanism and bundling it with Audacity or whatever.

    Nor that they generally have a lot going for them beyond convenience- even I (a non-audiophile) have heard enough that I'd go for something better if I still had anything left to digitise!

  14. Stevie


    Bolting on budget tape kit to CD-equipped, er, equipment started the minute manufatcurers realized they needed to dump all their good but not stellar range of tape transport chasses.

    I bought a boom box in 1984. It has servo-driven heads and track search built in, along with all tapes made compatibility and Dolby II noise reduction (which was standard buy then). Cost about $150 if I remember right.

    Fast forward ten years and I get a similarly priced box from the same manufacturer featuring two tape decks (woo!) and a CD player. The tape decks feature metal/FeO2 compatibility but not the proper capability to deal with Super Avalyn type coatings. There is no Dolby noise reduction whatsoever. Head movement is by levers under the buttons. In short, old cheap tat.

    I would like to add that while I had tape decks go belly up, they were universally the portable ones I strapped to my hip that got well bashed and smashed in a given day, and it was always the door latch that went, *not* the tape transport itself. All my non-portable cassette gear is as good as the day it was bought, practically. I tell a lie, I had a cheap in-car unit eat its own drive belt so I tossed it.

    In the same time period I've gone through three mollycoddled CD players due to various failures, usually chip/CB related or read head servo failures that required no bashing or smashing at all.

  15. Anonymous Coward
    Anonymous Coward

    I keep my Philips DCC deck for converting analog tapes to digital as it outputs the sound to optical out.

    You're best switching off all the dolby crap and using some decent noise reduction plugins on your computer. You can at least tune and refine the effect unlike a dolby switch which is just on or off.

  16. RobHib

    Just checked the specs of my Nakamichi 680 ZX

    "For chromium dioxide tapes, the frequency response figures in the manual quote 50Hz~12.5kHz +/- 3dB."

    You're correct about the specifications of the CD-A750, and the fact that gear isn't just the same as it once was.

    The manual of my Nakamichi 680 ZX reads as follows:

    Freq response: 10 - 22,000 Hz +-3dB (@ -20dB rec. level)

    S/N ratio: 66dB (IHF - A weighted, ref. 400Hz @ 3% THD with Dolby NR, ZX tape, 70 usec equalization)

    Total Harmonic Distortion: 0.8% @ 400Hz, 0dB rec level, on ZX tape (1.0% with SX & EX11 tapes)

    Wow & Flutter: 0.08% weighted peak, 0.04% weighted RMS

    Erasure: better than 60db @ 1kHz, saturation level.

    There's a half speed 15/16" too:

    Freq response: 10-15,000Hz +- 3dB ( (@ -20dB rec. level with ZX tape)

    (That'll do, the rest of the 15/16" specs are similarly degraded over 1 7/8" but still excellent.)

    Funny, but this Naka 680 ZX has better specs at half speed, 15/16", than does the CD-A750.

  17. RobHib

    XLR Balanced inputs look the part but are they?

    "This model looks the part with its rack mounting ears and a peek around the back reveals XLR connectors for +4dBu professional balanced line level interfacing."

    XLR Balanced inputs look the part but are they? Correctly balanced 600/150Ω inputs are great as they balance out the crosstalk through CMR (common mode rejection). Traditionally, very high quality transformers were used for this purpose in HiFi applications. They usually used high B/H (high permeability) steel for the laminations and it was usually sourced from Sweden. (Incidentally, the old POTS (analogue) telephone industry had the balanced transformer design down to a tee, their world revolved around balanced 600/150Ω circuits. The audio industry essentially adopted the telephone standards and improved them for HiFi.)

    In recent times, people have taken an irrational dislike to audio transformers and wherever possible they eliminate them, which, in most cases, is a silly decision. Eliminating them for unbalanced circuits is usually OK but it can be quite problematic for balanced circuits (i.e: the XLR/600/150Ω inputs/outputs).

    The problem comes from the fact that it's difficult to get a true balance with respect to Earth, that is one side of the balanced circuit has both a different impedance and capacitance to earth than the other side and thus the crosstalk suffers, also hum loops can occur (usually these effects are a non-event with a good mu-metal-shielded audio transformer).

    When transformers are eliminated on balanced circuits, special circuits, such as a 'long-tailed pair' (differential amplifier), are employed and fancy impedance matching is used to create a 'virtual' Earth. In essence, the Earth pin on the XLR is often terminated in this virtual earth rather than connected directly to the chassis earth (please electronics guys, I know this is an over-simplification, we don't need a thesis here). Also, by default, such circuits are usually high impedance (>10kΩ) and some fancy work is done to lower the impedance to ~600Ω. All up, a low-noise, properly-balanced, transformer-less input (or even output stage) is quite a complicated and sophisticated design. And more often or not, its design becomes a fudge--a half-baked kludge that's all too often seen, even on quite sophisticated designs such as used in [some] professional audio desks.

    It would be interesting to know how the CD-A750 tackles the problem. I'd guess with less than exemplary specifications it'd be a kludge.

    Anyone know?

    1. A J Stiles

      Re: XLR Balanced inputs look the part but are they?

      I'm convinced that balanced lines are now a bigger problem than the problem they were originally intended to solve; which was noise pickup on small signals.

      Balanced lines are sound if you're dealing with tiny, noise-prone signals that have to be routed along long cables to an amplifier. And because you have to use a transformer anyway to match the low output impedance of a dynamic microphone to the high input impedance of a valve amplifier, there's very little cost increase from having the low-impedance winding centre-tapped.

      But we can do wideband, low-noise, low output impedance amplification nowadays, and with gain to throw away. In confined spaces, even.

      There is no need even to match impedances at the sending and receiving end anymore; in audio, upstream of the power amplifier at any rate, we're more concerned with keeping the shape of the waveform than with getting as much energy transferred as possible. It's not a problem to amplify the tiny signal coming from a microphone or an instrument pick-up right next to the source, if needed; and its output can be at a sufficient level, coming from a sufficiently low impedance, to be essentially noise-free, even on an unbalanced cable.

      The balancing and unbalancing stages are probably making things worse, even.

      1. RobHib

        @A J Stiles -- Re: XLR Balanced inputs look the part but are they?

        "I'm convinced that balanced lines are now a bigger problem than the problem they were originally intended to solve; which was noise pickup on small signals."

        You're of course correct. Balanced lines are best confined for use with dynamic mikes and specialized instrumentation that use sensors which have very low-level outputs. I actively discourage the use balanced circuits; it usually complicates things to no real benefit. (Balanced audio became popular in HiFi as it was hangover from both telephony and the days when valves predominated. Not only were audio circuits balanced but also so were AC valve heater circuits to minimise induced hum (here, a humdinger potentiometer would ground heaters at a minimum hum point). With solid-state, balancing is usually unnecessary as there's less noise pickup: heaters are gone, so is the very high input Z of valves and shielding is easier.)

        I also agree with you about the impedance matching. Except for very small noise-limited circuits, RF receiver inputs etc., baseband video over coax and in transmitter-antenna power coupling and such, Z-matching is a waste of time. The once common bridging/terminating switch that chucked a terminating load across the input of audio lines [and which screwed levels up] is, thankfully, mostly gone (as S/N is now normally limited by other factors).

        There is, however, one audio application where +4 or +8dBm line levels should be balanced and that's where the lines are long such as in radio and TV stations and concert halls etc. I recall an installation where about 17kms* of audio cable were used and it would not have been possible to run unbalanced line-level audio. Here, only the best shielded balanced cable could be used (Belden Belfoil 8761 albeit now superseded), and the cables terminated in patch panels using gold-plated LEMO connectors where the cable earth looped through the panel rather than to it (for source or destination earthing)—all to stop hum and crosstalk. Through necessity, both microphone and line-level audio (and sometimes unbalanced 75Ω video) would run in the same ducts (unfortunately a common practice, but often unavoidable).

        * Of course, each cable was only some hundreds of meters in length.

        Maintaining the noise to within a few dB of the theoretical thermal noise for 150/600Ω on the mike lines in such installations is a tall ask and it's essential that not only the terminating equipment's (recorders, audio desks etc.) circuits are well designed but also the lines are well balanced. Thus the quality of the cable construction is of paramount importance, both with respect to overall shielding and the balance (close tolerances on the capacitance between cable and shield etc.)

        It's in environments such as this that CD-A750 cassette/CD combo would require properly balanced inputs and outputs. Moreover, I'm strictly of the view that XLR connectors should never be wired as unbalanced. Unbalancing XLRs not only causes confusion but it can introduce crosstalk and noise into an otherwise clean audio network. (Hum loops are a notorious problem when two of the three pins of an XLR connecter are grounded, it's a common problem with breakout boxes).

        One of the annoying problems when equipment with electronic rather than transformer balancing is used in such installations is that longitudinal hum and noise often becomes a problem. RF detection (RF noise from mobile phones, radio stations, clicks from electric motor switching etc.) is much more likely to be induced into such circuits than when a transformer is used. Audio operators also exacerbate the problem of crosstalk, hum and noise by using unbalanced breakout boxes and such (which they love and won't part with on threat of death—as sometimes threatened by annoyed techies).

        Furthermore, in these complex environments, high-level audio from power amplifier outputs (speaker feeds) are also often balanced to reduce both the crosstalk induced into low level mike circuits and to overcome the I^2 R losses in the long cable runs. Here, the so-called '100V line' feeds are fed by low-to-hi-Z transformers. In installations where hundreds of power amplifiers feed from central control rooms to distant locations, there's little other choice.

  18. Fihart

    Self defeating Disc Tax

    "Audio CD-R" discs are hard to find and retail for much more than data CD-R which became a cheap commodity while Audio version remained a tiny niche market. In reality the only difference between the Audio CD-R and a regular data CD-R is some code on the Audio disc which the recorder recognises.

    The idea of the "tax" (actually a small amount before the above market factors came into play) was to compensate record companies (and musicians ?) for anticipated losses due to pirating of albums using such machines. But the recorders were expensive and unreliable. And they didn't sell because it's quicker to rip CD albums and copy them on a computer.

    So the main buyers of CD recorders were musicians recording their own work. Thus, the Audio CD-R price premium penalised only those it was supposed to protect -- but that's tax for you !

    I have Philips CD and Sony recorders which I use for transcribing vinyl to CD. I use Audio CD-Rs bought very cheap in flea markets or occasional end-of-line offers at stores. It's possible to use data CD-Rs on a recorder, with a little ingenuity. Involves leaving the recorder's case open and some deft swapping of discs once the Audio CD-R has been recognised. Simpler method is to use Audio CD-RW disc in the recorder but then copy the RW onto regular data discs on a computer. A quick wipe and the Audio CD-RW can be reused ad infinitum. So, as usual, tax avoidance or evasion wins.

  19. darklord

    still got my deck

    still got my yamaha deck from 25years ago. admitted its in the loft with a whole load of cassettes.

    but loathe to get rid god knows why ill never use it again, Also got two vcrs up there again which dont get used.

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