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General preamp question....

Discussion in 'Preamps / Channel Strips' started by therecordingart, Jun 15, 2005.

  1. therecordingart

    therecordingart Well-Known Member

    I want to make sure that I understand this correctly.....this might sound dumb....

    Let's say that I were to mic an ok sounding snare with an SM57 and run it into an average consumer pre. Now without changing the mic, distance, or snare I then unplug it from the average pre and into a great pre. I know that I won't be waving a magic wand, but would the overall snare sound better, just more detailed, different frequencies brought out? I'm having a hard time coming up with what I'm trying to ask. So nevermind...next question....

    I have a GT Brick and want to mic a snare. Now...will I screw up the Brick since there isn't a pad or does the pad just attenuate the output? I've mic'd a kick successfully once, but every other time the output was way too high for the insert on my board...clip city! Is there a decent pad you can recommend? (not maxi smart-ass!)
  2. Kurt Foster

    Kurt Foster Distinguished Member

    The answer to all three questions is yes. It will sound better, more detailed and different frequencies will be accentuated.

    As for the second question, what kind of mixer are you using? The Brick shouldn't be clipping it ...

    ... and second, why are you running The Brick into the mixer in the first place? The whole idea of outboard pres is to bypass the mixer and go directly into the recorder.
  3. stickers

    stickers Active Member

    secretly, he asks this to validate purchasing the API 3124..its ok man i understand..hehe
  4. Reggie

    Reggie Well-Known Member

    Actually........On snare I had level problems too. So I got one of these: http://www.shure.com/accessories/a15as.asp
    For some reason kick is no problem, but close mic snare gives my A/D a bit too much volume. The Brick doesn't care though.

    Funny thing though, clipping my RME converters didn't sound terribly bad at least on a quick snare hit. It seemed to just tame transients without getting into that crazy digital distortion. I still probably prefer having unclipped signal, but it wasn't the end of the world! :?
    I'm guessing clipping converters on input is even bolder than EQing signal on input.
  5. Kurt Foster

    Kurt Foster Distinguished Member

    What is the sensitivity of your converters inputs?
    The Brick wants to see at least +4dB input sensitivity.

    Possibly some converters have a little extra headroom built in? I heard this about the old Alesis ADATs but I don't know if it's true.

    With analog (tape) the onset of distortion is gradual. With digital, once you go over the limit, full distortion occurs immeadiatly and "it ain't pretty" ... you do not want to clip digital :!:

    Whether digital clips are audible or not can depend on how many samples are clipped ...if it's very short duration, it's not so audible ... maby ok when tracking (I still discourage it though) but an absolute no-no at mix (it drives the MEs nuts!).
  6. Reggie

    Reggie Well-Known Member

    ha ha If that is the case, maybe you should also look into the Seventh Circle Audio stuff. I hear they sit with API pretty well, and it will save you about $1000 I think on 4 channels with room to expand (about $330/channel after that; less than a Brick!). I have 2 channels coming to me now, so I will report how they sound and how much of a pain it was to build. I'm hoping I might learn something useful about electronics troubleshooting and repair in the process too. And I will have a valuable job skill so I can go work in a Chinese factory when they take over.
  7. RAIN0707

    RAIN0707 Guest

    Do you have to take your shoes off before entering the factory? Or is that custom Japanese? I forget, haha
  8. therecordingart

    therecordingart Well-Known Member

    Kurt, I hooked it up the way you told me to. I plugged the output of the Brick into one of the inserts on my FW1884. That was the only way to bypass the preamp.
  9. Kurt Foster

    Kurt Foster Distinguished Member

    Can you pull down the fader on the channel strip to attenuate the signal?

    If you're thinking API, I believe the OCA or Seventh Circle stuff are direct clones ... and should have the same characteristics.

    Another pre that has that API flavor but is a bit different is the JLM TMP8 ... at $2100 (depending on the exchange rate) the TMP8 is the most affordable (on a per channel basis) of the bunch. I have one of the newest versions of it here right now for evaluation ... JLM has added direct inputs to all channels and a new power supply connector. The first unit I had here a year and a half ago had the soft limiters bypassed at my request. I loved that pre but JLM needed it back for a client. I was sad to see it go. I was happy to hear from Joe when he contacted me and told me he was sending me a second updated unit for assessment. I am not letting go of this one. I waited too long to get a replacement :!:

    The new TMP8 I received has the soft limiters engaged. Normally the limiters are set to engage at +29dBM indicating the mic pre is about to clip at +30dBM. There are 3.5 mm mini plugs that are inserted under each channel that custom tailor the settings for the limiters to your DAWs inputs.

    Remove the plugs on any or all channels and essentially the limiters are bypassed ... insert them and you can drive the snot out of these pres, making them very "Neve-ish" sounding.

    Somewhere between a Focusrite Red and an API in terms of sonic signature, the TMP8 is killer.
  10. Reggie

    Reggie Well-Known Member

    Yeah, clipping the main fader on mixdown is big nasty. But for some reason it sounds OK clipping the snare into the A/D. Not great, not bad. Looks retarded when you zoom in on the graphic display and see the chopped peaks, though; but I guess it is another case of using your ears!

    If I wasn't getting into this whole DIY thing so much right now, I would probably get the JLM TMP. Pretty killer deal, and I am a wuss, so I would like having the safety net of the limiters.
  11. AudioGaff

    AudioGaff Well-Known Member

    Partly true. The original ADAT's had the meters calibrated so that when you hit the red (0dBFS) you still had 3-4 dB of headroom left. They knew all to well that people would be pushing the limits like they were used to on analog tape decks.
  12. Reggie

    Reggie Well-Known Member

    I checked the Multiface manual and it says this:
    "Analog headroom prior to AD conversion: 13 db"

    Don't really know how that works, but it sounds like it does have some headroom built in. I heard someone say that they preferred the sound of running their final mixes out and back in through their RME converters clipping off 2-3 db, to the sound of their L2. Still haven't gotten around to trying that myself, but I might for giggles when I get a chance.

    Weird stuff.

    PS: sorry to sidetrack the thread :oops:
  13. Kurt Foster

    Kurt Foster Distinguished Member

    Reggie, That's the headroom of the analog stage before the converter. Converters have NO HEADROOM over 0 dB on the digital scale. 0 dB is IT! Nada! NO more .... Who said they "preferred the sound of running their final mixes out and back in through their RME converters clipping off 2-3 db, to the sound of their L2" ??? :shock:

    That seems very silly to meeeeeeeee ...

    If you try to send a CDr or a file to a pressing plant that has one single "over" on it, they will most likely reject it saying it has errors. Perhaps that technique works for someone who is burning their own CDrs at home after they have performed some"bullsh*t mastering" but it will not fly with an ME or a duplicator.
  14. Reggie

    Reggie Well-Known Member

    Ahh, yeah I obviously don't understand the tech specs, but could you explain how the analog headroom works on a AD converter? I don't understand why there would be headroom past what the converter can pass. :? :oops:

    It will be a miracle if I can find that thread I was talking about, but I think it was in the Mastering forum and some guys were tossing around their thoughts on the L2. Maybe someone over there knows what I'm talking about?

    And I don't believe a master will get rejected at replication just because all the audio isn't under 0. It is still data, just a different number. 00000000 0000000 00000000 00000000 However some CD players may have trouble with not reading this as a clip and it might just sound a little distorted at its crappy DA.
    I have heard quite a few other converter clipping stories. I know you can't go past 0, but a good converter can sort of act like a brickwall limiter if you go easy (and you really like pushing the limits of volume).

    But by all means, don't take my word for it.
  15. Kurt Foster

    Kurt Foster Distinguished Member

    The headroom in the analog end is so the electronics have a bit of room to "breath" and not sound strained ... it helps preserve liniarity .. etc. The idea is to allow the signal to not sound "strained" or "stressed out", you don't want the analog circut and the digital one to be approaching clip point both at the same time.

    As far as 00000 0000, that's all fine but if the pressing plant sees something over 00000 0000, it will appear as a clipped waveform / error they will reject it. If you don't believe me ask one of the MEs who know what they're talking about over there in the Mastering Forums ...

    You do not want to intentionally clip digital to compress ... that's just not a good idea.
  16. Reggie

    Reggie Well-Known Member

    Ahha I guess that makes sense, I'm just not entirely clear how the 13db analog headroom relates to the 0db digital headroom. Anywho....

    I don't think there is a way to make a master with anything over 0000...... I may be wrong here but I thought the errors that cause a master to be rejected have more to do with the burning process and the media used. I don't think they have a clue if they are replicating something that has clipped audio unless you are having it mastered at the plant also.

    I don't know that I said anything about that. I was just talking about using it to bring in a few stray transients that are robbing digital headroom to begin with. Remember, louder is always better, heh heh. (edit: BTW to avoid any confusion if there is any, you can't do this within software. You have to go out of the box and back into the converter.)

    Oh, and I'll be danged if I didn't find that post I was talking about. I don't know the guy Lagerfeldt or if he knows what is what, but here is the thread if interested:
    (Dead Link Removed)

    Can't wait for the next kid with a Soundblaster card to start asking about clipping his converters for mastering. :lol:

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