Conference napalm::commusic_v1

    
    Brad,
    
    The multitrack cassettes and small format reels use dbx or Dolby C to
    help out with the crosstalk issue. Make sure that NR is on and
    calibrated. Also, compress the click track from the HR16, and +3dB
    sounds a little hot as well. Try under zero.
    
    FX pre or post...depends on what you're using th channel for. If you're
    using it for an effects send, then set it post fader to control the
    effects with the slider. If you're using it for a normal input, and
    want to control FX via an effects bus, then set it pre fader.
    
    CdH
    

    
    You'll find that pre-fade allows wider control of dry
    to totally-wet....like strings far away in a huge hall, ya know?
    
    The few studio sessions Ive done I noticed that any sync
    stripe or automation control track is put on an EDGE
    track, with AT LEAST ONE guard track (ie, unused) right
    next to it. This is usually track 23,24 (or 31,32?)...but
    the big machines dont have staggered heads...
    
    ron
    

RE: sync

    The 238 has built in features for sync on channel 8 ("tape sync"
    switch, which defeats dbx on 8, and a "filter" switch, which bandpass
    filters all signals except specific midrange/FSK type bands). 

    Funny - trk 8 is an edge, and I had *nothing* on 7.  Hmmm.

    All that stuff was set up properly.  All I can come up with is that the
    drumswere simply being recorded "too hot".  Which brings me to another
    question ... 

    Howcum I record a track at a certain level (say, 0 db) but it plays
    back at -3db?  It's happened on every deck I've ever owned/used. 

RE: pre/post fade EQ

    That's kinda what I thought.  With the QV, I can control the wet/dry
    mix via MIDI CCs, so I usually just use pre-fade.

-b

    
>    Howcum I record a track at a certain level (say, 0 db) but it plays
>    back at -3db?  It's happened on every deck I've ever owned/used. 
    
    This is a calibration issue.  A correctly calibrated deck will adjust
    the record gain so that anything measuring "0" on the (source) meters will
    read "0" on playback.  On some home machines, there are levels for
    "Dolby calibration" and they do just that; Dolby playback level of "0"
    VU is carefully stipulated (a 400 Hz tone is used) and you essentially
    calibrate the tape you are using so that you put the correct amount of
    signal onto the tape to make it meet the playback criteria.  Confused
    yet?
    
    If your tapes always play back low (as you stated) you will get treble
    loss due to miscalibration if you use Dolby, or in the case of dbx, you
    may get exagerated "breathing" effects.
    
    A secondary problem is the question of the effect of EQ on the meters. 
    Tandberg decks read the record signal *after* record EQ is applied
    since this EQ is largely treble boosting and can contribute to tape
    saturation and self-erasure.  Self-erasure is a property of tape such
    that once it is saturated, increasing the signal to the tape causes the
    tape to actually retain *less* signal.
    
    A third problem is head alignment and tape "skewing".  If the track
    doesn't line up perfectly with the playback head, you can get signal
    loss.  This problem is more prevalent with multi-head machines (this is
    why Nak machines with 3 heads have an azimuth adjustment, they actually
    let you move the PB head until it "lines up" with the tape tracks).  On
    machines like Portastudios which use a combined record/playback head,
    this should not be an issue.
    
    Changing from one tape type to another, getting a different batch of
    the same tape, going from C-60 to C-90 lengths, even skipping a head
    cleaning before each session can all cause miscalibration.  I see this
    on my home deck, since I have the capability to calibrate from the
    front panel (all oscillators are built-in), I bias and adjust Dolby
    level for each tape just prior to recording.  Amazing how much I have
    to adjust the controls from one cassette to the next to keep things
    within 1 dB.
    
    							Brian

    Er - okay ... but this thing has no built-in mixer, or EQ or anything
    else to deal with.  The head similarly is dual-function (playback or
    record) so I seriously doubt an azimuth problem. 

    A "brute force" example: I recorded FSK to chan 8, using a direct out
    from the HR16.  Set incoming signal to 0db on VU meters (peak meters,
    if it matters).  It plays back at -3db on the same meters.  Are you
    talking about the same thing?  How in blazes do I calibrate the deck?

    Incidentally, this is the first time it's been used since I got it. I'd
    think that the chances of it arriving (direct from Teac) in an
    uncalibrated state would be minimal ... ?

-b

    
    The EQ I'm referring to is internal adjustments.  All tape decks
    perform record and playback equalization, that's why you have "tape
    type" switches on home decks.
    
    As I said, different tapes require different settings. If Tascam set it
    up for Maxell XLII and you're using TDK SA or whatever, that could
    cause a mismatch, believe me.
    
    							Brian

    I see.  Perhaps I should try using a TDK (I've used only Maxell UDXLIIs
    to this point).  If that doesn't work, looks like I'm going to be
    making my own blasted adjustments.

    At least the M50 sends out several test tones so I *can* calibrate.

-b

    Brad, My 688 is essentially a porta studio versionof the 238. I've
    striped to tape a couple of times and had NO crosstalk or problems with
    any of the tracks...your deck may need an alignment.
    
    dbii

	re .8 

	Does it seem likely that a combined record/playback head can
	shift position between the record pass and the playback passes? 
	Guess it could be possible that the head laminations aren't
	parallel to the tape tracks, which might really lower the
	machines specs, kinda like trying to do helical scan without
	spinning the head... 

	If I had to bet money, I'd say the levels were too hot.  That'll
	definitely cause the bleedover.  Brad, can you strip at a lower
	level?  Maybe the production line miscalibrated your 
	meters...  Time to get your own calibration tape!

	re: .9 

	This question "Brad, can you strip at a lower level?" was subject
	to, uh, transmission errors.  This question should have read
	"Brad, can you stripe at a lower level?"  We regret the
	inconvenience to any readers who may have sprayed tea/coffee into
	their keyboards. 

    I went back and determined that I did indeed have a level problem;
    there's a pot on the rear of the 238 that controls the signal level
    coming in on track 8 in sync mode - the HR was reading -3db, and I
    bumped it up to 0db.  So far, no problem. 

    Here's another weird problem - I have all my gear patched into a Roland
    M160, then into a Tascam M50 which is the tape deck board.  The M160 is
    dead quiet, but I get this annoying hum (sounds like 60 cycle) at the
    M50 in.  This is presumably because the M50 accepts only RCA ins
    (-10db) and the M160 sends a +4db signal out 1/4" or XLRs.  I'm using
    good Roland 1/4" to RCA cables (ones shipped with my MKS70).  I figure
    that either the cords are improperly shielded, that one or both of the
    cords is bad (doubtful), or that I have a line level mismatch. Any
    ideas? 

    Another oddity - I seem to consistently get a "whirring" sound on tape
    (kinda like an electrical motor starting & stopping).  By consistent, I
    mean "inevitably", because I can't reproduce it at will, but it'll show
    up every so often when I have everything powered up.  I don't think I
    have an appliance on the same circuit, much less on that kicks on as
    often as this appears (I can count it at least once every minute).
    Ideas there? 

    Slight aside - I did get rid of some of the residual system noise by
    moving the Kurzweil 1000PX away from the mixer - it originally was
    mounted directly underneath the M160.  I kept getting a strange hum
    until I moved it to the bottom of the rack.  Very strange. 

    Anyone have electrical noise problems associated with wall bugs? 

+b

    Brad,
    I just noticed last night, as a matter of fact, that the whirring of
    the PC disk drive comes in over the metronome cable from my OP-4001
    MIDI interface. Could you be having a similar problem?
    
    I also experienced a noisy hum from my 1000PX apparently related to
    a ground loop, which you may have seen described in a previous note
    a while back.
    
    Good Luck - I hope you solve your whirring problem.
    
    Bill

    
    A "whirring" sound is usually some RF being emanated from something
    with a microprocessor on board, i.e. you're picking up some kind of
    clocking signal. Check your grounding!
    
    							Brian

    Er, grounding? {blush}  We have no grounding in this house.  In fact, I
    had to use a ground lift on the main power strip for this very reason. 

    I checked everything over and am pretty sure that all polarized plugs
    are uniformly "plugged in".  What else can I do?  I can't seem to
    isolate the noise to any single unit. 

    I should know this by know.

+b the embarassed

    If you have no grounding, take any *one* unit and ground it to a water
    pipe.
    
    							Brian

	Another thing you can do is to get some braided ground cable and
	connect all of the components cabinets together.  This helps in
	some situations, but be sure that all of your polarized gear is
	polarized the same way.  To be supercautious, before you put the
	braid in, tie it to one component and use a DVM to measure the
	potential between the braid and each of the other components. 
	You should also take precautions not to juice yourself in the
	process in case one of your components cabinets is accidentally
	energized. This braid essentially duplicates the electrical path
	provided by the shield of your line cords, but with lower
	resistance...so the theory goes. 

    	Sometimes you can get the hum (60Hz) from too much grouding.
    A ground loop can be set up if you have multiple gound paths to
    your central ground point, like your mixer. This happens more if
    the two paths are of different lengths but the jist of it is that
    they work like large antennas, picking up any electro-magnetic 
    interferance. Midi cables will not provide a ground path if properly
    wired, only signal cables. To fix this problem, the shield or ground
    at one end of the offending cables should be cut. This maintains
    the shielding from the other end but breaks the loop. BE SURE THAT
    YOU HAVE AT THE ONE GROUND PATH, because if its unplugged all you
    will get is hum.
    
    	This proceedure may only be required between key pieces of gear
    such as your tape machine(s) and the mixer, processing gear (2 or
    more cables to each). The discovery of which piece(s) are the offender
    is on a trail and error basis, and maintaining which cables are which
    takes some organization.
    
    	re .before_somewhere
    	Ground your central grounding point in your set-up to a good
    ground in your house, like a water pipe. You may want to be able
    to disconnect this easily if you get a lot of lightening in your
    area. In fact disconnect it all from the outside world when not
    in use......
    
    		From The Society For the Prevention of the Premature 
    FRYING of Favourite Gear due to  High Tension Electro Static Discharge 
    between the Earth and the Vapourous Gasses surounding it.

    Here's what I've got, from a kind of top-view perspective.  I have all
    my synth gear plugged into a Roland M160 in a rack. 

	 +----------------<------------<---------<--+  (2 �" to RCA cables)
	 | +-------------<------------<---------<-+ |
         v v                                      | |
	+------------------+	+------------+	+-------------+
	|    Tascam M50    |--->| Tascam 238 |	| Roland M160 | \
	|   12 x 8 mixer   |<---| 8tr casset |	| 16x2 mixer  |  \ *large*
	+------------------+	+------------+	|-------------|  /  rack
                                                |  all other  | /
                                                |  MIDI gear  |/
                                                +-------------+

    One power strips acts as a master, and has 3 things plugged into it:
    the M50, the 238, and the rack (one line to the rack).  Unless there's
    a ground problem between the M50 and the rack, I'm inclined to dismiss
    a ground loop. 

    When I listen to the headphone out of the M160, I get ABSOLUTELY NO
    NOISE AT ALL. 

    The M50 is dead quiet until I plug in the cables coming from the M160.
    Then I get the hum.  Note that these cables are the small ones, kinda
    like "cheap guitar cables".  Could this be the problem? 

    Turning the tape deck on or off has no effect on the signal. 

+b

    Brad, you don't mention what audio gear this is all plugged into.
    I had very similar symptoms and searched for hours to find the cause.
    I eventually traced it to my audio pre-amp. I had one of those adaptors
    that allows you to connect directly to the t.v. cable for FM reception.
    Removing that removed the hummmm completely. 
    
    The lesson I learned was to check the not so obvious as well as
    the obvious.
    
    I doubt whether thee cables are the problem if they are screened.
    Don't be too neat though in your routing, a tangled mess is sometimes
    better than a nice tight bunch.
    
    Ken
    

    Well, I took everything apart and went thru piece by piece.  First off,
    the wiring in this part of the house is about 50 years old, and has no
    grounds whatsoever.  So I tried running a ground strap from the rack
    (from the entire power strip as well).  No dice.  So I disconnected it. 

    Then worked backwards from M50.  When it was the only thing powered up,
    it had 60 cycle noise (!).  A ground lift fixed the problem.  Next,
    connected tape deck.  No noise introduced when running tapes for any
    reason.  Fine - M50 and 238 work together with no noise. 

    Next - power up rack piece by piece.  M160 connected to M50.  Some
    noise, probably due to +4db outs connected to -10db ins ... properly
    attenuated, there seemed to be very little noise.  Power up KX76 and
    Atari ST.  No noise.  Power up Oberheim.  No noise.  Power up MKS70. No
    noise (I'm beginning to appreciate Roland products more and more).
    Power up MIDIverb.  Notice slight hiss, but no noise. Power up HR16. No
    noise.  Power up Proteus.  No noise. 

    Power up Quadraverb (mounted immediately beneath M160 in rack). Argh!
    Lots of low frequency noise.  Power up Kurzweil 1000PX.  AUUUGGGHHH!!
    INCREDIBLE amount of noise.  Power off everything but M50, 238, M160
    and 1000PX.  No help.  It's definitely the Kurzweil.  What gives?

    I moved the Kurzweil to the bottom of the rack (as far away from
    everything as I possibly could) but it didn't help - as soon as stereo
    ins are connected to the M160, here comes the noise.

    Could the 4 wall bugs in the bottom of the rack be causing the
    problems?  Maybe the Kurzweil can't deal with the noise from them? And
    why doesn't the MKS have the same problem? 

    A P330 is starting to look *real* good.  8-(

+b

    Hmmm.  Next steps include trying a filter/surge protector on your
    power lines (if you haven't already).  You might try (carefully) checking 
    line voltage with a meter.  If the rms voltage looks good, try (even
    more carefully) looking at it with a scope.
    
    Steve

    My PX didn't have any noise problems like that.  It did have a large
    problem with my Atari Screen however...
    
    Chad
    
    (the atari screen really had a large problem with it really)

Putting together what Chad said with what Brad said, I would think that
the Kurtweil unit is emitting a fairly hefty low-frequency
electro-magnetic field, perhaps from its power supply transformer. 

In Chad's case, this was picked up by the electron beam in the Atari
monitor, and caused the image to deflect, which caused a visible 10hz
wobble.

This same electro-magnetic field could be easily picked up by any
transformer or even just wires in the proximity of the unit.  So while
the hum comes in and out with power applied to the Kurtweil, it may be
some other device that is actually generating it on the audio.

All just theories, mind you, but something to think about.

    re Kurzweil EM interference and hum issues - mine's in a rack under the
    EMAX and over a TEAC stereo 10 band graphic EQ - never a problem.  If
    you're getting hum thru the AUDIO outputs, you have either a massive
    grounding issue or a failing power supply.  IMHO/INE (I'm No Expert)
    
    karl