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Converters for Synths

Discussion in 'Converters / Interfaces' started by otnemem, Jun 29, 2004.

  1. otnemem

    otnemem Guest

    Hi all,


    I´m a musician who is growing into the recording stuff, so I would like to ask for your advice on ADCs.

    Currently I use a Yamaha 02R, but I´m running out of channels and the ADDA extension card gives me level problems all the time : no synth seems to get more than -12 dB out of this card, so I´m pretty much limited to the 24 input channels with gain.

    Since the 02R ADCs are somewhat outdated, I see two ways to go : Either drop the complete unit and do everything in the computer from now on (already got a Hammerfall) or skip the 02R converters and use ADAT cards in all slots plus external ADCs (which could be used with a DAW later on).

    Now here is my problem :

    I use some fine analog gear like the Studio Electronics SE-1 and ATC or Waldorf Pulse, i.e. I would like to preserve that special analog punchiness and warmth as far as possible when using a digital mixing desk. Plus my Nord Modular seems to be a bit low on the level side.

    I´m sure I don´t need some ADC that is designed for microphone work, since this demands yet another level of quality when compared to line signal conversion. However, I don´t trust that a ADA 8000 will give me the result I need, especially when recording my analog babies. High Quality Line Signal Conversion is what I´m after.

    I stumbled across the RME Octamic, which is still affordable and does everything I need. However, 4 of these units are out of this world.

    Is there anything you can recommend in between eh cheapo ADA 8000 and Octamic ? Or do I need to sell my kidney :eek:) ?

    What is imported to me :

    8 channel ADC
    ADAT or TDIF, don´t need both
    single channel gain (that´s why the ADI8 is out)
    gain like in mixing desk, not just a+4 / -10 switch


    Maybe there is something you can recommend ?


    Thanks in advance,

    Oliver
     
  2. AudioGaff

    AudioGaff Well-Known Member

    May not be right for you but on the less expensive side is the M-Audio Octane which has eight mic pre's and ADAT I/O. It can even be used to bypass the mic pre using the line in's. Seems to me to have the best mic pre they have every made.

    Sure your level problem is not inproper gain staging? Or are you using any balanced and unbalanced I/O connections interfacing wthin your signal path? This can often create a 6dB-14dB difference in level.
     
  3. otnemem

    otnemem Guest

    uh, oh, now that you say it....

    I guess almost all synths here have unbalanced outs while I´, pretty sure the ADDA card has balanced - it´s designed with analog multitrack recorders in mind..

    signal path then looks like this :

    unbalanced out - mono cable - balanced patchbay (neutrik) - stereo cable - balanced input

    hm, i will try to connect directly in order to minimize error sources, but maybe something is wrong with the cable.

    what would be the best way to connect ? simply using mono cables all the way and hoping that the ADDA card is handling this well ? or do this between the synth and the patchbay and stay balanced between patchbay and ADDA card ?

    I´ll take a look at the Octane as well, just scanning the market at the moment. From what I´ve heard, the RME Multiface, which is normally used with their PCI or cardbus cards, now works in standalone mode as an analog to ADAT and back converter, another one to look at.


    Thanks again,


    Oliver
     
  4. realdynamix

    realdynamix Well-Known Member

    :D I can't comment on your converters, but I use the analog outs on synths, many of them are at instrument level normally. Even though the specs say +4db, it depends on the sample dynamics vs. the velocity curve and other things. Instrument level is somewhere between -10 and -18 on average.

    I think this was engineered that way to plug into stage amps so as to not overload the inputs. Even on an analog board line in, I have to kick up the gain. A cheap fix would be an 8x8 line level shifter/noise eliminator like EB-Tech which uses tranformers to up -10db levels to +4db, this would provide plenty of gain. I never got one because I can't get the spec sheet on their website to open..??? But other company's make them as well. I have Aphex converters at work, well made. Lietch makes some as well.

    Another thought, if the source is unbalanced, and you use a TRS connector on that end, it must normalize the ring and tie it to sleeve, if not, it will only use one side of your balanced input, leaving it several db down...as much as 20db. The balanced input must be properly unbalanced to keep the level correct.

    Hope this helps,
    --Rick
     
  5. otnemem

    otnemem Guest

    Hi Rick,

    thanks for your advice, I´ll take a closer look at the cabling these days. If nothing is wrong there, then the "booster units" you recommended will be on the list ....

    The transition between unbalanced and balanced should happen in the patchbay, since the patchbay to mixer cabling is completely balanced, just in case there is a balanced source.

    I would have expected neutrik to have some circuit design that recognizes whether you plug in a stereo or mono jack and then do the proper thing... if not, i need to unsolder a lot of mono TRS plugs and replace them by bridged stereo ones. there would be no advantage is using stereo cable from an unbalanced synth to the balanced patchbay, right ?


    Later,

    Oliver
     
  6. realdynamix

    realdynamix Well-Known Member

    :D The only trouble I see there is how the jack is in the synth. This would ONLY apply if you are using TRS cables. If ground only touches sleeve, then your balanced input, post patchbay, will see the low side as open, and you won't get full gain. On my E-mu box, the ring is actually an aux return. Most of my outboard midi stuff is sleeve only ground. If your patchbay recognizes a standard TS plug, and normals your mixer input to unbalanced, then everything should be OK. I don't like to have to gain up a synth, it adds too much noise. The EBtech raises the gain with tranformers only, now...that's why that spec sheet is so important, what effect does it have on the sound? The Aphex units have amps and provide +/- 6db of additional gain control.

    --Rick
     
  7. otnemem

    otnemem Guest

    Hi Rick,

    sorry for this late reply, but I wanted to try some things first and get some facts, it just took some time.... I hope you are willing to help me understand some of the elec-tricks, it´s something I just get started with :)

    Now here are the specs of the mixer inputs (02R) :

    Actual load impedance : 10 kOhm
    For Use with nominal : 600 Ohm lines

    at +4dB
    Sensitivity : -6dB (388mV)
    Nominal : +4 dB (1.23 mV)
    Max before clip : +24 dB (12.3 mV)

    at -10 dB
    Sensitivity : -20 dBV (100 mV)
    Nominal : -10 dBV (316 mV)
    Max. before clip : +10 dBV (3.16V)

    Because of the low level problem, I switched the card to -10 dB.


    I did some tests and came across this :

    When sending a 0dB test tone from the mixer to an SDE-330 and setting the gain of the SDE so that the level just hits the clip indicator, I get between -30 dB an d-18 dB (coarse levelmeter) on the Tape Return inputs of the mixer.

    When going directly from the unit into the mixer, nothing changes, no matter if I use mono (TS) or stereo (TRS) connection. The same is true for all combinations of cables with the Neutrik patchbay in between. So I guess we can sort out the cabling as the source of trouble.

    Next I tried any available output from the various synths I got here and, surprise surprise, there are HUGE differences between the various boxes. What makes me scratch my head : If I use the Elektron Machinedrum, or Studio Electronics analog synth, I get full level on the mixer inputs. So there is nothing wrong here. Again it is no difference if I have the patchbay in between or not. But other gear I thought to be high quality as well (Clavia Nord Modular) gives me very poor level, even with the loudest programs.

    So it seems that most of the synths just don´t have enough power to feed the mixer. On the normal inputs, this is a no brainer, that´s why there are gain pots. On the analog expansion card however, I can´t turn any pot, so I wonder what would be the best way from here : Would mic-preamps be a good choice ? Or are these too sensitive because they were made for mics, not synths ?

    If a mic-preamp is the way to go, would you recommend anything with the special (ab)use I need here ?

    Thanks in advance, best regards,


    Oliver
     
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