Share DP24/32 Equipment Related Tips

Discussion in '2488 and DP-24/32 Digital Portastudios' started by cmaffia, Jan 7, 2019.

  1. cmaffia

    cmaffia Moderator Staff Member

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    Topics geared toward understanding the DP24/32 environment:
    • File Import;
    • Connecting Outboard Gear;
    • Signal Levels;
    • Impedance Matching;
    • Passive Transformers and DI Boxes;
    • Recovering From Software Boot Failure;
    • Recovering From a File Error Message;
    • Selecting a Monitor or Reference Speaker.
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  2. Mark Richards

    Mark Richards Well-Known Member

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    AUDIO DEPOT FILE IMPORT:

    Caveats to keep in mind:

    (a) The name of the file brought into Audio Depot must be no more than 15 characters.wav (e.g. xxxxxxxxxxxxxxx.wav) or the Unit will not even list it for import.

    (b) The Import screen of Audio Depot will truncate long file names to 8 characters.wav (e.g. xxxxxx~1.wav / xxxxxx~2.wav / etc.)

    (c) The sample/bit rate of the file(s) you're importing must be the same as the song to which you're doing the import.

    When importing files via Audio Depot, it's important to remember that the Unit display will truncate long file names to 8 characters. So 'mysong1trk15.wav becomes 'mysong~1.wav'; 'mysong1trk16.wav' becomes 'mysong~2.wav', etc. on the Unit display.

    Knowing this can be important if you are exporting your song to consolidate all the snippets for each Track into a contiguous flow for re-import to the Unit (e.g. so you can free up space on the SD card).

    Audio Depot will export the actual zz000--.wav files as song-name plus the individual Track numbers as the last few characters. But the Unit's display will truncate to eight-places.wav when imported back, removing the Track numbers at the end of the file names.

    So if Track order is important when using the 'Import' function, before making the import to Audio Depot, open Audio Depot on your computer and rename the files on the computer to place the Track number first, e.g ‘T15mysong1trk15.wav’, ‘T16mysong1trk16.wav’, etc. This will make things a lot easier when they are brought back to the unit via the 'Import' function. Just remember that the actual file name must be 15 characters or less.
    Last edited: Jan 7, 2019
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  3. Mark Richards

    Mark Richards Well-Known Member

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    CONNECTING OUTBOARD GEAR (Compressors, Reverbs, Mixers, etc.)

    DP-xx A~H Low Impedance (LowZ) XLR (Balancd) Mic Inputs & DP-xx High Impedance (HiZ) 1/4" TRS (Balanced) Phone Line Inputs
    • TRS and XLR inputs/cables have two hot wires and a ground shield inside. The same signal is carried through both hot wires.
    • Typically one signal is made out-of-phase with the other electronically by the receiving device's input circuitry and only one of the hot wires carries the signal into the receiving input circuitry.
    • The out-of-phase signal cancels out any noise that built up in the signal.
    This is an oversimplification, but the idea is to compensate for signal loss in long cable runs by eliminating noise buildup so a clean signal can be raised up to a usable level at the end of the long cable run.

    You need to pay attention to the input (Load) / output (Source) impedances of the outboard gear and the input (Load) / output (Source) impedances of the DP-xx. The Load Impedance should be at least 5x the Source Impedance, and preferably 10x or better (more on that can be found in the post on “Impedance Matching”).
    • The DP-xx XLR Mic Inputs are Low Impedance – 2.4kOhm (LowZ Load)
    • The DP 1/4" TRS 1/4" Phone Line Inputs are High Impedance - 22kOhm (HiZ Load).
    • The DP-xx TS/RCA and TRS 1/4" Phone Line outputs are all High Impedance – 22kOHM (HiZ Source)
    DP-xx Out (Source) to Outboard Gear In (Load)
    • The DP-xx Send and Stereo outputs are HiZ RCA/TS (unbalanced) jacks out.
    • The DP-xx Monitor phone jacks out are 1/4" TRS (balanced). If connecting via the DP-xx Monitor out, keep in mind the Monitor out circuit puts out significantly more power than the RCA outs since the Monitor out is designed to connect to powered speakers or a power amp.
    • On the outboard gear, the HiZ input could be a TS/RCA unbalanced jack, a TS 1/4" Phone unbalanced jack, or a TRS (balanced) 1/4" phone jack. You need to check the specs of the outboard gear to make sure you are matching the DP-xx and the outboard gear outputs and inputs.
    Outboard Gear Out (Source) to DP-xx In (Load)
    • The outboard gear outputs to use must be HiZ for pairing with the DP-xx HiZ line inputs.
    Warning: The DP-xx XLR LowZ mic inputs are not compatible with HiZ XLR outputs found on some outboard gear. You absolutely do not want to run a HiZ XLR output into a DP-xx XLR mic input. The outboard gear is not a microphone.​
    • If the outboard gear has TS/RCA unbalanced jacks out, then use TS/RCA (unbalanced) to TS 1/4" phone plug (unbalanced) to connect into the DP-xx Inputs (A~H) and set the Trim Pot full left (counterclockwise).
    • If the outboard gear has mono (TS) 1/4" (unbalanced) phone jack out, then use 1/4" mono (unbalanced) phone plugs to connect into the DP-xx Inputs (A~H) and set the Trim Pot full left (counterclockwise).
    • If the outboard gear has TRS 1/4" (balanced) phone jacks, then use TRS 1/4" balanced) phone plugs to connect into the DP-xx Inputs (A~H) and set the Trim Pot full left (counterclockwise).
    The big advantage in using matching connections on each end whenever you can is simplicity and peace of mind (the KISS philosophy).

    IMO the least expensive and most practical method is to keep the entire link High Z/unbalanced if the cable run is short. You can use 1/4" TS male connectors on both ends, even if the outboard gear output jack and the DP input jack are TRS balanced. If the High Z cable run is >12 feet (4 meters) and both devices have TRS jacks, then TRS male connectors should be used. In either case, set the DP-xx trim pot full left at the line level setting, and use the source outboard gear’s signal output control (not the DP’s Trim Knob) to adjust the level coming into the DP.

    If you are dead set on connecting the HiZ outboard gear into the DP-xx LowZ XLR mic Inputs (A~H), you are very strongly urged to use HiZ to LowZ impedance step down transformers. The transformer typically would be TS 1/4" plug on one end for connection to the outboard gear; male XLR on the other end. The transformer connects to the DP-xx using a standard XLR M/F mic cable or XLR M/F short patch cable. The necessary step down transformer and the cable should be available at most pro audio stores (more on that can be found in the post on “Passive Transformers and DI Boxes”).

    Balanced Cable v Unbalance Cable

    The only time a balanced cable is a better option than unbalanced is when the cable run needs to be longer than about 4 meters (or about 12 feet), or if there's a specific problem with R(adio) F(requency) I(nterference) - like florescent lighting may cause, or a computer may cause; or a pesky ground loop exists. Absent any RFI or ground loop problems, there's nothing wrong with using an unbalanced cable and connectors for short cable runs. If the cable run is under 6 feet I would use unbalanced cable.

    Problems can crop up where TS/TRS/XLR type adapters are used, typically when the adapter shorts out the signal due to a mismatch of input/output types.
    Last edited: Jan 8, 2019
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  4. Mark Richards

    Mark Richards Well-Known Member

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    IMPEDENCE MATCHING:

    Think of impedance in terms of water flowing through a pipe. The larger the pipe, the greater the volume of water can pass through the pipe, from minimum flow to maximum flow without backing up. Ideally, you want to match the incoming flow of water to the flow capacity of the pipe to maximize the efficiency of the flow.
    • The XLR mic input jack is low impedance (2.4 kOhm - two thousand four hundred Ohms). This is mic level - all mics with XLR cables are low impedance. Do not connect high impedance sources to this XLR input jack.
    • The 1/4" Phone input jack is high impedance (>22 kOhm - twenty two thousand Ohms). This is line level. Connecting a low impedance mic to the high impedance 1/4" phone jack requires a low to high impedance transformer that is XLR on one end and 1/4" TS phone plug on the other.
    • The Input H "guitar" switch converts the 1/4" phone jack impedance from 22 kOhms to an extremely high 1 mOhm (1 million Ohms). This allows directly plugging in the guitar, which itself is high impedance (typically 40kOhms), but is twice as high as the DP’s line level input impedance, which creates an undesirable impedance mismatch.
    • If using a pre-amp or stomp box in the guitar chain prior to connecting to Input H, do not set the “guitar” switch to the “On” position unless the source's own impedance is greater than 22 kOhm. Typically the 1m Ohm impedance is not needed with a stomp box in the chain and turning on the “guitar” switch may lower the signal, add noise, or introduce some other type of signal degradation.
    It's okay generally to run a low impedance device into a high impedance device. The only downside is lower sound/more noise in the signal level than there would be when pairing the low impedance output device with a low impedance input device.

    It's very bad to run a high impedance output device into a low impedance input device. Distortion and signal degradation is the least of the bad things that can happen. Permanent damage to delicate electronic circuits is the worst case scenario.
    Last edited: Jan 8, 2019
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  5. Mark Richards

    Mark Richards Well-Known Member

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    DP-xx SIGNAL LEVELS:

    (The "Level Diagram" in the Specifications section of the DP-xx owner manual is a good visual reference)

    The dBu numbers (see above reference to the owner manual) are all in reference to the difference between the lowest signal input that can be processed and the maximum signal level the circuit can handle referenced to a standard voltage (OdBu = .775 volts).

    For the DP-xx, OdBFs = +2dBu. The DP-xx can handle a line input level of +20dBu, but that is +18dBu over OdBFs. In the digital world, anything over 0dBFS is distortion, so there is no such thing, for example, as +3dBFS.
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  6. Mark Richards

    Mark Richards Well-Known Member

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    PASSIVE TRANSFORMERS AND DI BOXES

    A passive transformer's main design purpose is to change the XLR microphone's output impedance from LowZ to HiZ, increase the mic signal by about +25dB, and filter out any cable noise at the HiZ input so that the LowZ mic can be used effectively with a HiZ input.
    • But it will also work in reverse, converting an unbalanced High Z line level output to XLR Low Z; and reducing the High Z line level signal by -25dB so it won't overdrive the XLR input.
    • If the High Z line’s output is TRS balanced, at the High Z/transformer connection the transformer (TS on the 1/4" phone plug side) treats the signal as unbalanced TS, turns it back into balanced, and converts the HiZ to LowZ. So TS v TRS has no relevance. The signal arrives as a balanced/LowZ at the XLR LowZ input jack.
    • A typical basic passive direct injection (DI) box is designed to convert an unbalanced HiZ guitar pickup signal to a balanced LowZ signal for connection to a balanced XLR input where a long cable run (>12 feet/4 meters or so) is required. Some advanced design DI boxes may function like a reversed XLR mic transformer.
    Last edited: Jan 7, 2019
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  7. Mark Richards

    Mark Richards Well-Known Member

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    MAKING A UNITY GAIN TEST

    This helps determine that "what goes in" is "what comes out".
    • Feed white noise into a Track. (White noise encompasses the entire audible frequency range. The easiest available source for white noise is FM inter-station noise. Just put a mic in front of an FM radio's speaker.)
    • Keep the Trim Knob full CW-mic (or full CCW-line if your source will be line level)
    • Set the Track Fader to Unity Gain - 0 dBFS position.
    • Set the Stereo Master Fader to Unity Gain (all the way up).
    • Set the Track pan full left. The Stereo Master Meter and the Track Meter should read identically. Monitor/listen to the white noise long enough to familiarize yourself with the sound.
    • Use your mic placement and the FM radio's volume control to bring the Track Meter level to or as close to 0 dBFS with no excursion into red.
    • Record about 15 seconds of the white noise. Rewind and play back. The Stereo Master Fader should read exactly the same as it did before hitting record. The audio should sound exactly the same as it did before hitting record.
    • Play back the recorded sound over your monitors and play the radio's inter-station noise at the same time and at the same level. They should sound identical.
    You can also use a free SPL (sound pressure level) smartphone app to measure the audio level of your source and monitor signals at the speaker to be sure the audio levels are identical. If they aren't, adjust the respective amplifier volume controls until they are.
    Last edited: Jan 7, 2019
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  8. Mark Richards

    Mark Richards Well-Known Member

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    RECOVERING FROM DP-xx SOFTWARE BOOT UP FAILURE

    It appears that the dp-xx.sys file may somehow become corrupted on untested SD cards, making it impossible to boot the DP-24/32.

    This process may make your card usable again, or at least make it readable on your computer so you can recover the music files.
    • After loading a failed DP-xxSD Card to a Windows PC, a pop-up screen will indicate there was a problem with the card and ask to fix it. Pressing “Yes” initiates the needed fix to the SD Card.
    • With the card now accessible on the computer, delete the dp-xx.sys file from the SD card.
    • From your computer’s DP- backup folder copy the dp-xx.sys file over to the SD card.
    • Eject the SD card from the computer; install it on the DP-xx. Turn on the DP-xx and...if the gremlins aren't paying attention and the planets are in alignment...the DP-xx may boot right up with no loss of music files.
    If the DP-xx wants to create the sys file on startup, do it, and once the card loads, transfer the contents to another card, and stop using it, because there's a good chance it's on the way to total failure.
    Last edited: Jan 8, 2019
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  9. Mark Richards

    Mark Richards Well-Known Member

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    RECOVERING FROM A DP-xx “FILE ERROR” MESSAGE

    The Scenario
    During a recording/overdub/bounce session, your DP-xx freezes, and after pulling the plug and restarting, the screen displays a "File Error" message when trying to load the song that you were working on.

    Possible Solution
    The last Track(s) you were working on when your DP-xx froze may have been corrupted and is preventing the song from loading.
    1. Open the SD card in your computer.
    2. Open the music/song folder.
    3. Starting with the highest numbered "zz" .wav file and working backwards from that file, test each file by trying to open it with a media player that plays .wav files.
    If a file doesn't open in your media player, it's been corrupted. Move the corrupted file from the song folder to another location and repeat until you have identified and moved all the corrupted files (typically it will only be the one or two most current Tracks you were working on).

    Remove the SD card from the computer, insert it back into your DP-xx, turn your DP-xx back on, and try to load the problem song.

    If the planets are in alignment and the gremlins aren't paying attention, you might just get the whole song back less the Track(s) you were working on when your DP-xx froze.
    Last edited: Jan 8, 2019
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  10. Mark Richards

    Mark Richards Well-Known Member

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    SELECTING A MONITOR OR REFERENCE SPEAKER:

    Some things to keep in mind when choosing speakers as a recording tool:

    (1) You need to consider whether you want the speakers as a monitoring tool during tracking and overdub; as a reference tool for mixdown/mastering, or both.

    (2) Another thing you need to consider is the instruments and type of music you'll be working with. This chart can help with that (click on thumbnail to enlarge):

    Music Frequency Chart (Color).JPG
    [Source: http://www.independentrecording.net/irn/resources/freqchart/main_display.htm]

    For example, for speakers with a stated Frequency Response (FR) of 80Hz~22kHz (but without a stated +/- x dB variance in relation to the standard 1kHz reference point) it's hard to judge how accurately the speakers will yield a recording that will sound good on other playback systems.

    • 80Hz~22kHz +/- 2 dB referenced to 1kHz is great - this is a flat, neutral response;
    • 80Hz~22kHz +/- 10 dB referenced to 1kHz - not so much - there's wide variation, and that will color unnaturally and in unkown ways your mixing/master recordings.
    Use the above chart to compare various instruments and voices to the stated FR for the speaker in which your are interested.
    • Will the speaker reproduce the lowest notes on a bass instrument, or only reproduce the higher overtones/harmonics of the lowest notes
    • Will the speaker reproduce a guitar and vocals nicely if there's reasonable variation (e.g. +/- 3dB). around the 1kHz reference point.
    Unless you've made a successful effort to acoustically tune your mixing room/listening position, near field monitors will be your best bet to minimize the impact on your mix of the room's acoustic anomalies.
    Last edited: Jan 8, 2019
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  11. David Porter

    David Porter Well-Known Member

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    Once again, Mark. Thank you. Your efforts, knowledge, and organization are invaluable and mucho appreciated. With the sticky's at the top of this forum now - this place has solidified itself as THE online resource for all things DP-24/32(SD).
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  12. Mark Richards

    Mark Richards Well-Known Member

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    David, thanks for your kind words.

    I hope this sticky encourages forum members to look here first for ideas and solutions, and to offer tips of their own (hint, hint).:)
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  13. -mjk-

    -mjk- Moderator Staff Member

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    Yes Mark, what David said.
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  14. -mjk-

    -mjk- Moderator Staff Member

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    I have a TC-Helicon Voicelive Touch 2. It has a Hi-Z guitar input, and a Low-Z mic input. The guitar input is for chord reference and passes through the effects chain in a totally different path. Only the mic input is fully processed by all 9 effects. Not long after I bought the unit, I read that it's possible to use it as an outboard processor by sending line level to it. Thinking that was a mistake, I wrote to TC-Helicon, and they told me to turn the input level knob fully CCW and use the XLR jack to feed the FX send from the console. Ever since then, I've been using it like a line level device and it functions perfectly. Clearly, they designed it this way, otherwise it would blow up the input.

    I'm using this unit as an external effects processor with my DP-32. Works very well.
    Last edited: Jan 7, 2019
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  15. Mark Richards

    Mark Richards Well-Known Member

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    I'll be darned.

    Tried it with my TC-Helicon Voicetone Harmonizer GX-T.

    DP-24 HiZ unbalanced Send 2 out into GX-T's XLR LowZ mic input, set full CCW to minimum input gain, and careful setting of the DP Send Levels.
    • Noting that -mjk- has the VoiceLive Touch 2, a step or two up from the GT-X and perhaps with better circuitry, on the G-XT I'm hearing slight distortion on louder sections even though the GX-T isn't showing any red on the input.
    • Also, to my ears it sounds like the HiZ to LowZ connection compresses the signal and kills the dynamics.
    • I think for the GX-T using a HiZ to LowZ stepdown transformer yields a much cleaner result.
    Turning the GX-T harmony feature off, it makes sense to be able to use the GX-T as outboard gear for its reverb, delay, and doubling effects. I tried out just the reverb & delay effects with an acoustic guitar...it did sound good, but mono only (no stereo spread from the returns using two DP-24 tracks panned L/R).

    So there it is folks...check with the manufacturer first, and take care with the levels, and rely on your ears.;)

    I think this equipment tips sticky thread could become a real treasure trove of information.
    Last edited: Jan 8, 2019
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  16. -mjk-

    -mjk- Moderator Staff Member

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    @Mark Richards why no stereo spread? The VLT2 does have a mono/stereo output menu setting. Might be worth checking for that. Mine sounds awesome, and I can even use the MIDI port for effects timing.

    Also, I had to turn mic boost OFF.

    I haven't done it yet, but you just know I'm going to use a Send from a dry vocal track to the main input, and the other Send for a clean reference guitar track to the guitar input, so the VLT2 can get the chord information from the guitar. Then I can sit back and overdub automatic background vocals.
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  17. Mark Richards

    Mark Richards Well-Known Member

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    mj, I was surprised the reverb wasn't stereo. It was also 2 A.M. when I was testing it...will try again when awake.
    EDIT: User Error.:cry:

    Overdubbing automatic background vocals works really well (see my followup post in this thread):
    http://www.tascamforums.com/threads/share-dp24-32-equipment-related-tips.5817/page-2#post-29671

    I've also programmed in the Major and Minor keys to the pre-sets so I won't have to rely on the guitar feed. I've found this produces much more consistent and accurate harmonies - a sad commentary on my guitar technique.
    Last edited: Jan 12, 2019
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  18. -mjk-

    -mjk- Moderator Staff Member

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    DP-32, | 2A Mixer, A3440
    @Mark Richards nice! Now, to triple-track (Queen style) and introduce the random element.

    All those vocals I did years ago were painstaking sung, 1 track at a time, tripled. Old school, like Brad Delp.
  19. -mjk-

    -mjk- Moderator Staff Member

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    Mark, did you get the outputs to work in stereo?
  20. Mark Richards

    Mark Richards Well-Known Member

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    Yeah, mj - it was just sleep deprived user error.:oops:

    The G-XT delivers a really nice selection of effects and harmonies.

    Almost makes me want to become an A Capella group of one.:D
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