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Help Digitizing Cassettes (Phase Reveresed)

Discussion in 'Recording' started by westy, Mar 19, 2008.

  1. westy

    westy Guest

    whats up guys im new here and just though Id ask you knowledgeable folk for some information and help digitizing cassettes. I am using a tascam 122 MKIII cassette deck and a RME HDSP 9632 ADC to convert. the cassettes are not your average off the shelf type they're mainly demos and in house record label references etc. when digitized the rips are good but when played in mono most of the center information disappears
    I sent a cassette off to a studio some months back and it also had the same problem, heres what the guy said..

    the left and right sides were out of phase! When listened to in mono much of the center information would disappear. So I have phase reversed one side and Im digitizing it like that

    when he sent back the cassette rips they were amazing, much better then the original unphased. could someone explain to me in layman's terms how I would accomplish this at home using my equipment and what software etc Id need, really appreciated
  2. JoeH

    JoeH Distinguished Member

    Jun 22, 2004
    Philadelphia, PA/ Greenville, DE
    Home Page:
    i've seen this happen before, although it is rare, esp with cassette decks.

    First, I'm assuming you're talking true phase-reversal, and not just heads that are badly out of alignment. (With that phenomenom, you lose high ends and get all kinds of 'swishy" phasey sounds when stereo signals are combined to mono. Different animal entirely....)

    What you're talking about sounds like truely phase-reversed signals from one channel relative to the other.

    What probably happened was that during the dub, somone had an XLR cable with a mis-wired connection - pins 2 and 3 were likely reversed. (Most of the Tascam Pro Cassette decks - includin the MKIIs have balanced, XLR inputs and outputs, yes?) You'd still hear signal through this line, but it would be in fact out of phase with the other channel. Perhaps the original dupe/copy room didn't have very good monitoring - if at all - or perhaps this was a one-off copy that somene just threw together.

    In any case, the music got printed onto the tape with one channel completely phase-reversed from the other. Anything in common was positive-going on one channel, and negative-going on the other. Hence the "Cancelling" effect when combined to mono.

    Once he identified the problem, your guy may have fixed it the old fashioned way, with his own BALANCED, reverse-wired cable going into his A/D convereter. (Pin 1 ground, pins 2 and 3 are the actual audio +/- signal). (Take a moment and read up on Balanced vs. Unbalanced audio lines, including something called "common mode rejection" and why it's used in pro audio.)

    You could do this yourself, with two XLR (mic) cables; one of them should have pins 2&3 reversed on ONE CONNECTOR only. (Assuming you have a Tascam machine with balanced ins/outs - XLR connectors. Take a look in the back; are there RCA jacks AND XLR jacks there? If so, you're good to go. You CANNOT do this with just the unbalanced RCA jacks alone).

    Mark this new XLR connector so you won't forget it's been altered, and remember to undo it aftewards, or keep it around for future use, as long as it's clearly tagged. (I have one 3-foot XLR on my rack of special cables for just this sort of thing....)

    If you don't have XLR outputs on the deck, you'll need to convert the RCA (unbalanced) outputs to a direct box or unbal/balanced converter before you go into your (XLR/line level) A/D inputs.

    If you don't have any of that, your software MIGHT have a phase reversal toggle/switch for one of the channels. Import the (out of phase) Left and Right channels from the cassette deck as separate, mono channels, and work from there. Depending on your software, you may be able to pull it off that way as well with something as simple as phase-reverse.

    As you know by now: always sum to mono to check your work!

    Good luck with it. :cool:
  3. basilbowman

    basilbowman Guest

    REAPER has a real easy phase reversal toggle, and stereo splitting, etc. If it's only for one home project, I'm sure Justin wouldn't mind you using it. It's got a 30 day trial period after all.
  4. westy

    westy Guest

    Wow, thanks for taking time out of your day to explain that to me
    Yes my tascam has in and out XLR double ports, the inputs can be switched from balanced to unbalanced

    u say to be able to correctly do this at home I would need two XLR (mic) cables; one of them should have pins 2&3 reversed on ONE CONNECTOR only.
    could you perhaps link me to those to buy on ebay etc? ive looked on the net and I am unsure as to what they are as I am a novice in this field
    Will these leads be XLR to RCA, so they go straight into my line ins on my soundcard?

    Again apology's for my lack of knowledge, The cassette I am currently digitizing when it is saved on my harddrive is played as ''surround sound'' for some reason? this RME HDSP soundcard is new and very complexed for me to understand it features a global record feature so I can monitor levels and allows me to set the sample and bit rates, but it dosent allow the change to mono stereo etc, what am I doing wrong here? when Its finished recording and I go to save it give me several option ie: save all channels, save multi file, 2 channel files etc..

    should cassette & vinyl be digitized to mono? and then changed to stereo when dithering down?
    I have no pre-amp in my setup, the cassette goes into my soundcard and the monitors out for playback

    would relaly appreciate some understanding to this, thanks so much thus far, this is a woinderful forum
  5. basilbowman

    basilbowman Guest

    I know the quick fix, I don't know the pro audio version, I think Joe has laid it out enough that it's doable and will turn out nicer his way, but if you want a quick and dirty bit, I can get you started... Hit Radio shack, pick up a cheap RCA-1/8' adapter, or a nice one, but no sense in putting too much money into it, wire that into the output jacks of your tape deck, then from that into the *LINE* in on your soundcard - NOT THE MICROPHONE IN. Pull up whichever program you're using to record, audacity or kristal or reaper will work fine for this. Start recording off your line in jack, punch play, dub it over to your computer, and go to town digitally, splitting it from stereo to two panned mono tracks, flip the phase, and put them back together. You might lose a lot of quality, but it'll get you started at least. Good luck!

  6. bent

    bent No Bad Vibes! Well-Known Member

    Oct 26, 2007
    Cocoa, FL
    No, Joe stated that one might have the polarity flipped in your setup currently - that's the problem. Both cables should be identical (not phase flipped).

    Neither should be flipped (or reversed, depending on your nomenclature).

    Edit> OK, Joe did say to flip one of them - as a test.
    (Sorry Joe). Anyway, I'm guessing that one is already flipped - or whatever method you used to interconnect the gear is the problem.

    Could be a balanced / unbalanced mismatch, in that case use the exact same cables and adapters on both channels as I mention below and you should be right as rain.
  7. bent

    bent No Bad Vibes! Well-Known Member

    Oct 26, 2007
    Cocoa, FL
    For further info:
  8. bent

    bent No Bad Vibes! Well-Known Member

    Oct 26, 2007
    Cocoa, FL
    No, record them in as either discreet (separate) L/R tracks or a stereo track.

    Go out of the XLR line outs on the back of the player into the main L/R inputs of the sound card - you may need an XLR to RCA adapter (or 1/8" stereo adapter as stated above).

    Depending on your setup, along with the XLR cables, you'll need two of the following:

    RCA Inputs:
    link removed


    1/8" Inputs:
    link removed
  9. westy

    westy Guest

    my sound card has L/R Line ins so i take it this would be ok? XLR female - RCA male
    btw I never made these cassettes they are from interscope & priority records etc, official demos and samplers

    really appreciate that bent & basilbowman, so always record as stereo (got it)
    this particular cassette is turning out to be a nightmare, i had noticed changes in the sound quality from time to time and didnt realise what it was, but discovered that on my tascam cassette deck dispaly its changing every 5 minutes or so to cr02 and then back to normal cassette, normal being the setting it should be set at and the best sound quality for, any ideas what this might be?
    many thanks
  10. RemyRAD

    RemyRAD Guest

    Sep 26, 2005
    I think you guys are all confused?

    Back in the day, because head azimuth was difficult to maintain, especially for cassette decks. Another company out West, called Pacific Recorders, or something like that decided to MS multiplex the left and right signals for their NAB cartridge machines. This solved the problem with mono compatibility and poor phasing. It was probably also utilized for cassette archives to maintain proper phase alignment. So what you have there is an MS encoded cassette.

    Poor azimuth then becomes wondering stereo with solid phase & mono compatibility. So try decoding these tapes as if they were recorded MS. Left will most likely be Middle. Right will most likely be Side. If you don't get a solid sense of center, try reversing your left and right prior to matrix decoding.

    If you have any further questions, don't hesitate to ask me.

    MS girl
    Ms. Remy Ann David
  11. Kev

    Kev Well-Known Member

    Nov 13, 2001
    this could be a very good call from Remy

    these cassettes
    " ... mainly demos and in house record label references etc ... "

    what sort of program material is this ?
    pop music
    or acoustic classical sort of stuff ?

    if this is an MS recording
    then qudos to a very wise Remy for seeing past the too obvious
  12. basilbowman

    basilbowman Guest

    Ya be makin' too much sense, Remy :)
  13. Boswell

    Boswell Distinguished Moderator Resource Member

    Apr 19, 2006
    Home Page:
    The MS-encoded theory is a nice idea but it doesn't quite fit the reported symptoms. The OP said when he sums the channels to get mono, "most of the center information disappears". MS-encoding when summed to mono gives 2L if the encoded tracks were in phase or 2R if they were out of phase, never L-R, which is what you get from summing conventional LR with a phase inversion on one channel. Now it may be that the monoed sound actually is 2L or 2R, and the OP got the impression that the original centre image was missing rather than a whole L or R channel. I think I would try a phase reversal on one replay channel first to see if that restores the correct sound image.

    The second thing that worries me is the recommendation to feed the Tascam 122 XLR outs directly into a computer sound card. The +6dBu level at these outputs is likely to overwhelm a standard sound card, irrespective of the balanced/unbalanced question. My memory of when I last used a Tascam 122 is that it has additional outputs at -10dBV on RCA (phono) connectors, so I would say the best thing to do is to use a simple stereo RCA-RCA lead into the soundcard, digitize the tapes as they are and then perform the phase flip or whatever is required as a post-processing operation. It doesn't take sophisticated software - even Audacity will do the job.
  14. westy

    westy Guest

    Hip Hop from 1993-1994

    thanks remy and boswell, much obliged
    I dont want to do much post processing on these recording as im trying to get the very best sound
    their is no harm trying all ways to see exactly what the problem with this cassette is, great advice..

    their is a breakout cable for my RME soundcard that I can purchase that feature XLR input, also in my soundcard setting I am able to choose +4db to compensate for the stronger signal

    question: will using XLR from cassette to soundcard yield better results for digitizing rather then RCA?

    also if anyone has any ideas why this cassette is changing the tape type from Normal to Cr02 on my tascam display? Cr02 being the incorrect setting and it makes the sound awful. I would be very grateful. thanks guys you're wonderfull
  15. bent

    bent No Bad Vibes! Well-Known Member

    Oct 26, 2007
    Cocoa, FL
    It's probably a dirty contact on the tape-selector switch inside the door of the player.

    Do your tapes have an extra bit of gap next to the record protect knock outs on top?

    If you use the XLR outs that I recommended, select +4 on your soundcard - and thank Boswell for catching that faux pas on my part.
  16. basilbowman

    basilbowman Guest

  17. westy

    westy Guest

    ^^ Thanks for the confirmation Basilbowman. and there I was using RCA the whole time, not knowing that XLR would give a better signal for digitizing cassettes. I suppose all the crap printed on the internet is misleading telling people to digitize with RCA, but if your card or cassette deck dosent have XLR ports then I suppose youve no choice
    I better buy the breakout cable for my soundcard that has XLR ports, that way I'll get the best volume and signal from these cassettes

  18. basilbowman

    basilbowman Guest

    Just remember to flip phase on one side if you're going to use standard XLR cables, otherwise you're no better off than when you started.

  19. Kev

    Kev Well-Known Member

    Nov 13, 2001
    gut feeling tells me that this is probably not an MS recording

    get another cassette deck for a test

    get a real test cassette to check the deck you have
    these test tones can then be transfered to the DAW
    allowing you to check frequency and phase (and polarity)
    and levels for both the XLR and RCA outputs

    if you don't have equipment
    zoom in on the wave form to see the alignment of the start of the tone and the polarity etc
    there may be a plug-in to show actual frequency of the tones
    the DAW level meters should give a good representation of the levels of the tones
    might also give you a chance to check wow and flutter
  20. westy

    westy Guest


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