Discuss the hardware aspects of playing music - tape decks, receivers,
CD-players, boomboxes, etc.

65 responses total.

We have seen numerous boomboxes with a switch on the back labelled OSC on/off
or beat cut A B or even A B C.  Does this apply to the tape or radio, and what
exactly does it do?

On some tape decks there is a button or level labelled Memory (on/off).  How
does this work?   And how do you use MPX filter on a tape deck - it is
sometimes associated with Dolby?  Does a Limiter switch limit the peak volume?
What is auto repeat used for?  Some decks have a timer feature - where do you
get a timer to go with it and what would they cost, or can you make one?

On a CD player, what do auto cue and time mode do?  I discovred what hitting
repeat does - it plays the same track over and over and over and over....

Jim asks what happens if you put 3 ohm speakers on a boombox that calls for
4 ohm speakers, will it damage either the speakers or the boombox if you don't
play music loudly?  He is proud to report that he is halfway through replacing
the foam surrounds of a couple of AR woofers with foam surrounds that he
carefully removed from some passive radiators (they look like speakers but
have no magnet or coil).  Today he glued (with carpenter's glue) the foam to
the cones, and tomorrow when it is dry he will glue foam to metal frame.
www.simplyspeakers.com sells new foam surrounds for $27/pair and was kind
enough to tell him old ones could be reused, and emailed instructions.  Remove
the old foam with sharp knife and alcohol.  He also glued the loose copper
coil of another speaker back into its cardboard tube, with superglue, after
carefully slicing off the dust cap (which he will glue back on tomorrow). 
It probably came loose when someone played very loud music.  THe matching
speaker to the pair had a broken wire which probably happened after the coil
came unglued.  Perhaps the glue just dried out first.

The neighbor gave him the superglue, along with a 10" woofer that has a
disintegrating cone.  Anyone have any dead 10" speakers to give away?

     ((( Classical 65  <--->  Music 82 )))

The MPX filter on tape decks is designed to get 
rid of the 19kHz pilot signal ("multiplex carrier"?) 
which is part of the FM radio signal.  That signal can trick the 
Dolby noise-reduction circuitry into misbehaving, and it may cause some
other effects; I've just noticed that in my recent taping of FM radio,
I get a lot of funny effects unless the MPX filter is on.

Someone else needs to explain the theory of how FM Stereo works, 
and how it was desgined to be compatible with monaural FM.
 
MPX filter should theoretically be left off for tapes from other sources
such as records and CDs, though at our age, and with the presumed quality 
of tape decks you are using, it probably wouldn't be a problem to
leave the 19kHz filter on all the time.   Experiment!

For a tape deck designed to work with a timer, any external timer which 
would control an AC power outlet would do.  The "timer" switch 
generally has two choices:  one to start tape playing when the power 
comes on, and one to start tape recording when the power comes on.
 
If you want to use your equipment to record on power-on, 
you have to be VERY, VERY CAREFUL about tape management, 
otherwise eventually you will make the mistake of turning the 
machine on while a valued cassette is in the machine, 
and the machine will merrily erase the recording.

Thanks Ken.  We only listen to FM radio in mono because of the hiss in stereo
when listening to any but strong local stations (none of which we listen to)
so should be safe recording without the MPX filter.
The Beat Cut A B C is for recording from AM if there is a whistle - try out
all three until one works.

We have several timers of the sort where you push little square pins/knobs
to the inside or outside of the timer to set it to go on or off every half
hour which we may experiment with.  Our friend likes to record a particular
radio show and keeps buying VCRs to do it with because they are timed.
These are sold for lamp timers but they are also nice for turning an electric
mattress pad on or off.

The foam surround project and the glue the coil in the tube project were both
complete successes and we are now trying to determine which two of four
woofers sound better together.

The instructions that came with one tape deck had a picture of what looked
like a stereo component, labelled timer, which looked expensive.  I suppose
if we don't mind being within 10 minutes the cheap sort will also work.

There is a little picture of a clock or timer next to the play and record
switches on one tape deck.  I guess you can also set it to work as an alarm
clock but there seems to be no sleep or snooze switch.

Sindi, Jim should have little problem using 3 ohm speakers where 4 ohm 
ones are required.  I don't think you'll blow them out, since I 
*highly* doubt you play music at maximum levels and music which 
strains the whole frequency of the speaker.  Classical music isn't 
known for that.  Modern music recorded in the studio-- say, techno, 
dance, etc., will be harder on them.

My system calls for 8 ohm- 16 ohm speakers, I believe.  I use an 
Optimus dual-coil subwoofer rated at 8 ohms, and two KLH 3-way 
satellites rated at 6 ohms each.  I'm only using the A set of drivers 
(it's a 140W stereo receiver).

The ohm ratings are only one part of the deal with speakers.  
Generally-- you want most of your resistance in the midrange speakers, 
with fairly little in the others, especially subwoofers.  Are we 
talking one-way speakers?  The ohm rating can dip really low for the 
others (you can get 1/2 ohm resistors for subs), so as long as you've 
got your midrange area decently covered, and in this case, it sounds 
like about 4 ohms, you should be perfectly safe.

(hehe, I told you this was a hobby of mine.) 

Those "ohms" are not resistance - they are impedances, and represent
the impedance matching between the source (amplifier) and the
atmosphere (the sound production). A mismatch primarily reduces
the efficiency of power transfer. However, because of other factors
in the component behaviors, a mismatch can also affect frequency
response and distortion.

The 3 ohm speakers that we are talking about are cheap black plastic ones from
a dead boombox that we put RCA plugs on to plug into a slightly less cheap
black plastic cube at Miller Manor.  Hopefully the future owner will not turn
up the volume enough to blow the speakers or damage the amplifier.  The cube
was donated without any speakers and was not selling.

One tape deck not only has MPX filter, but the Dolby is marked on, off or FM.
Would one switch on both FM and MPX filter to tape stereo radio?  Does anyone
actually tape stereo radio nowadays?

That last one is a puzzler; I would have guessed that "Dolby FM" would 
have been a switch position which would also have turned on the 
MPX filter in addition to the Dolby B noise reduction.
 
I still tape "A Prairie Home Companion" and "The Thistle and Shamrock"
(in stereo) on many weekends.

It is plain Dolby, not Dolby B.
We have tape decks with either plain Dolby, or Dolby B and C.  If we tape with
plain Dolby can we play back with C (or B?) and vice versa?  I read somewhere
that Dolby  (original) was more expensive so was dropped in favor of B and
then C is better than B.  Then there is DBX (on one machine)- if we tape with
that how would we play back on other machines?

Tape selector - EX, SX, ZX   ???  Normal (I), II, IV?
How to set bias and equ for the different tape types?
We have one machine that recognizes them automatically, some are labelled I
II III IV, some Fe CrO2 Metal, some just bias and equ.  We have a couple
machines with adjustable bias - what do we do with that, if anything?

I haven't got time to do this justice...  I will have to come back 
and write more later.   

Dolby and dbx Noise Reduction both work by compressing parts of the 
signal on recording and expanding them on playback.  When the signal is
expanded on playback, the volume of the tape hiss, relative 
to the signal, is reduced.   The systems differ in their choice 
of what to compress.

dbx is a straight 2:1 - 1:2 dynamic range compression 
scheme.  This system was very effective 
at nearly elminating tape hiss, but it was so 
aggressive that it sometimes introduced some audible modulation 
of the tape hiss, which was called "pumping" or "breathing."
It was pretty much agreed by everyone that dbx tapes were 
intolerable to listen to on machines which did not have dbx 
decoding.  I never worked with dbx equipment.

In the Dolby techniques, the amount of compression done to 
the signal varies with the audio frequency.  The higher
the frequency -- the more likely the signal is to get lost in tape 
hiss -- the more compression is done.   This is not as effective
as dbx, but it also means that a Dolby-encoded tape can be played
back without decoding, and most people won't object too much to the
resulting sound -- it's a little "bright" because the high frequencies
have been boosted.   This is considerably more complicated than dbx
and to work best, it requires that the tape deck be properly tuned
to the tape being used.

    Dolby A is a professional noise reduction system.  You will not find
    it in home audio equipment.
 
    Dolby B was the first Dolby noise reduction product for home use.
    Any cassette deck you find with a switch marked just "Dolby" 
    is controlling "Dolby B" circuitry.  Dolby B was introduced maybe
    around 1973, for a guess without looking it up. 
    Dolby B gets about 10db of tape hiss reduction -- much less 
    than dbx, but the tapes sound OK if played on equipment without Dolby.

    Dolby C was the second home version, introduced maybe around 1979.
    In a perfectly working system it got 10dB more tape hiss reduction,
    but because it was such an aggressive system it was more audible 
    when there were small tape/machine equalization problems,
    and Dolby C tapes sounded somewhat shrill when played without 
    decoding. 
  
    Dolby S came out after I had stopped paying attention to 
    cassette technology.


Tape selector switches of EX, SX, and ZX tell me you've got your hands
on a Nakamichi brand tape deck, because those were Nakamichi's 
own names for the tape formats.  Some Nakamichi models in good 
working order are quite collectible, selling for hundreds of 
dollars.  Nakamichi was usually regarded as the premier manufacturer
of cassette decks from the early 1970s into the CD era.
However, because Nakamichi and the rest of the world disagreed on 
how equalization was to be done, tapes recorded on Nakamichi machines
sound "dull" on other manufacturer's machines.  I have considerable
experience with this; I lived with or owned three Nakamichi recorders
back in the cassette era.

Tape formulations: roughly equivalent, on each line:
 
 Type I = Normal = Ferric = EX
 Type II = Chrome or Chrome-Equivalent = CrO2 = SX
 Type III = Ferro-Chrome = FeCrO2   <-- this formulation failed in the market
 Type IV = Metal = ZX
           Type IV / Metal tapes can be played back correctly with a 
           switch in the Type II/Chrome position, but they cannot be 
           so recorded.

Actually *explaining* them will have to wait.

Essentially I'm trying to write a complete tutorial on cassette
technology and this may take a while....   :) 
 
For a practical summary on dbx and the various flavors of Dolby:
my suggestion is that you record with Dolby B switched on 
(that's marked as "dolby" on some older decks) and play back with 
either Dolby B or no noise reduction, depending on which your 
ears like best.   That's what I'm doing these days.

Tape bias and equalization: hoo boy, that's gonna take a while to 
explain...   

We have a Kenwood with Bias Preset and Auto Bias that apparently detects the
tape type as that is not a choice. Yes it was Nakamichi with the EX SX ZX.
We have about 20 tape decks, some of which work.  CrO2 is sometimes just
labelled 'high' - high bias?  Some tapes are labelled 120 (I, normal?) and
some 70 (II, IV?) - is this bias or equiv?

We will skip dbx since only one deck has that and take your advice to use
Dolby (B) rather than C.  Don't have any S.  Jim likes to hear things brighter
- perhaps his hearing is shot from too much hammering, but he turns on Dolby
during play for tapes not recorded with it.  

One deck has settings Normal (120 msec), FeCR (70), CrO2 (70) and Metal (70).
Is the FeCr same as FeCrO2 that you mentioned as type III?  Some decks require
you to set both bias and equ and various combinations work for I, II and IV.
For instance both buttons out for I, both in for IV, one in and one out for
II.  A couple of these decks are not understandable.  

If you are interested, Ken, you are welcome to come over and admire and even
play with our tape deck collection.  We are still trying to fix one good one
to the point where it:  plays, records (both channels), and the door works.
We are replacing belts, tires, motors, springs and other bits and pieces.

Were home tape decks first popular around 1973, or even earlier (without
Dolby)?

We have encountered a variety of autoreverse mechanisms.  Usually the head
and tape stay put and the spindles/rollers switch direction, either by some
system of gears, or by acctually reversing motor direction (would this be by
changing polarity to a DC motor?).  One deck swivels the play head, and we
ran across one that actually turned the tape over for you, a very early model.
MCM electronics sells new autoreverse play heads for $2, or the swivelling
type for slightly more (also IEEE printer cables for about $2-3, of the type
that our friend paid $25 for recently).

resp:8  I typed in impedance, but wasn't sure if that was right.  Ok, 
I learned something new now.  Ok, Rane, if a system calls for 8ohm-
16ohm, will there be a match only with 8 or 16?  Or can you have a 
match with impedance in between, as I did?

Ok, Ken-- on the subject of Dolby, where does HX Pro fit in?

and just on a separate note, do noise reduction systems exist for 
TV/VCRs any more that are *separate* units?  I've noticed the really 
huge TVs with surround sound systems often have dbx noise reduction.  
I also remember Radio Shack carrying a separate audio decoder (I 
think) that allowed for stereo hookup and noise reduction, but I 
haven't seen it in years.

Hoo boy.  I can't explain Dolby HX Pro without covering "bias."
And I'm not even sure I can explain that very well; I may go out
and look for a URL to point you to.
 
In brief:  Dolby HX Pro is not a noise reduction system at all.
"HX" stands for Headroom Extension; it is a circuit to reduce
the bias current a bit when there is lots of high frequency
energy present in the musical signal, to try and stop too much total
high-frequency signal from going into the record heads.  Dolby HX Pro 
is only applied in the recording process; no decoding playback 
is required.

My last high-quality cassette deck had HX Pro, but I eventually 
concluded it didn't help the sound and I turned it off.

All right then, if HX Pro is only applied in the recording process, 
why would a deck need that system?

I think I'm somewhat familiar with bias-- many cassette types apply 
most of the bias in the midrange.  It seems to emphasize more of 
that 'warm' sound the cassette medium is known for (as opposed to LPs, 
which generally tend to be 'bright'.)  But I know that's grossly 
oversimplifying things.

The marketing for HX Pro argued that when too much high-energy signal
went into the record heads or tape that there was some "self-erasing"
going on, resulting in less-than-optimal high frequency performance.
So that's why it was called "HX Pro," for Headroom Extension.
Once the system accomplished its goal of getting a hotter high-frequency
signal onto the tape, there is no need for any special processing 
to play it back.
 
You know, the more I write this stuff, the more I remember why
I'm recording stuff digitally these days...

well, that's not a bad thing, actually.  Me, I just got a better 
cassette deck because I was patching a little compact stereo to a 
receiver for the deck.

Having Dolby playback is nice.  And yes, HX Pro sounds fine on just 
about any good deck.

        I still have an outboard Dolby box.  Control knobs on it 
to control things.  Came with a reel to reel tape and as cassette
tape for calibrations.

Tim is there any stereo gadget that you don't have and would like to get?

        I haven't had an eight track recorder for some time.

Does that mean you want to own one again?  I know where to get one, cheap.

Heh.  Watch out, Tim.

        I think even radio shack has stopped selling blank 8-track tapes.

I know where you can get cheap used ones.

What did I say?      8-{)]

  Since this is the "Equipment for Playing [Recorded] Music" item,
  I thought I might mention my recent purchase of an Apple iPod.

  I'll write a longer review of it later, but basically the iPod
  is an amazing device with a couple of annoying omissions and
  restrictions that keep it from being perfect.  Still, I'm quite
  happy with it, and can recommend it with only minor reservations.

We have discovered that the only tape decks with timer switches (you set them
to off, record, or play) are the ones were you cannot press down the regular
play or record switch and have it stay down.  The newer ones are solenoids
(feather-touch) and the timer switch is not needed on the older ones - you
can just push down the pertinent lever, plug the deck into a timer, turn on
power, and when the timer reaches the right time the deck should go on.
This is theory, anyway.

We have one (broken) deck with HXPro which is automatically used, and then
also a choice of Dolby B or C or neither.  It is autoreverse and plays okay
in one direction but superfast in the other.  Pinch roller not pinching.

Jim is fixing small headphones this week.  They come in 20,24, and 32 ohms
and you have to turn the boombox way up to hear them.  Is this to prevent
people from making themselves deaf?  Ordinary speakers are 4-16 ohms.
The larger the headphones, the less you have to turn up the boombox.

I can't find the previous discussion of MP3 portable players, so I'll
use this item.  I broke down today and got a RioVolt CD/MP3 player.
It was stickered at $99.99, scanned for $10 less than that; the sales
clerk waved a 10% coupon under the scanner and the price went down some
more, and *then* there is a $20 rebate which I darn well better send 
in this time.   So, what, $60-$65 final cost?  Yay Best Buy.  Thanks 
to mcnally for encouraging me to keep looking.
 
There were a frustrating ten minutes of trying to figure out the 
folder navigation, and then it all made sense.  
 
Sounds great on these Spanish folk MP3s by a band called Na Lua 
which I've been playing; certainly those files sound better on the 
the Rio than they do on Winamp on the computers I've got around.

I've been thinking about getting one of those for my son.  I figured we 
can take it in the car, too.  With a couple of MP3 CDs, we'll have 
enough music for a weekend trip to my brother's place south of 
Nashville.

I saw one in one of the Sunday circulars for $40, with car kit.  I hope 
that means a cigarette lighter plug-in and not a cassette tape adapter, 
since I don't have a cassette player in my car.

"car kit" generally means a cigarette lighter plug-in for power, and 
a cassette tape adapter to carry the audio from the portable unit
into the car stereo.  Most people's cigarette lighters are not connected
to the car stereo for output, but you might have a special model.  :)

As John doesn't have a cassette tape player, he'll most likely
have to get a small radio transmitter which can be picked up by 
your car's FM radio; I have no experience with those.

We were discussing these toys in another item somewhere recently, 
but where?

I have used such a tape/CD FM transmitter. They  work quite well. Their
only problem is that if you enter an area where there is a regular
FM transmitter, you need to pick another frequency. This doesn't happen
often.

  I've got one of the FM-transmitter doodads that I use with my iPod on
  car trips.  It seemed to work pretty well on my trip from Washington
  down to Utah and around the national parks of the southwest but it was
  a complete failure on a later road-trip from western Michigan to 
  southeastern Minnesota via Chicago.  From about Benton Harbor, MI,
  to Madison, WI, the device wasn't worth using -- about every 20 minutes
  I had to retune to an unused frequency as I came within range of some
  new low-power FM station.

  re #30:  For that price I'm presuming you didn't get the black model with
  the larger display, extra buffer memory, and FM tuner.  That's the only
  Rio/Volt model I'm familiar with, but I liked it.  The lower cost models,
  though much more attractively priced, seemed decidedly not as nice.

When is somebody going to invent the stylusless cartridge for playing 
vinyl?  Maybe not a cartridge, exactly, but some sort of optical device 
for reading the grooves on an analog vinyl recording.  Or has it 
already been done?  The idea of having to run a diamond-tipped needle 
through the grooves every time you want to listen to an old favorite 
seems more and more primitive and destructive of the medium, given 
current technology.  How hard could it be to come up with a simple 
inexpensive device?  

I've wondered about this, too.  But it will take more than just a cartridge,
as the needle controls the inward spiral motion of the cartridge as well as
vibrating.  You'd need something to make the tone arm pivot at the proper rate
to keep the cartridge pointed at the right point on the groove.

I also have to wonder whether something couldn't be designed with a *wide*
cartridge that would read the entire side in one revolution.  Might be
simpler.

My recollection is that the laser turntable *was* done; however, it was 
in the late 1980s, when the market for $10,000 turntables was shrinking
fast.  I will grub around later today; I saw something on the web
about it.
 
Mike in resp:35 :: My RioVolt model is the SP-90, blue case, seems to have
the larger display but no FM tuner, and I'm not sure about the buffer
size.

re #32: Urp.  Thanks for pointing that out, as I'd completely 
overlooked it.

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