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Pre-amp Gainstaging

Discussion in 'Pro Audio Equipment' started by apstrong, Jun 21, 2009.

  1. apstrong

    apstrong Active Member

    Alright, I took the plunge. I'm trying out a UA Solo 610 tube preamp. So far I have only been trying it out as a bass DI, and I'm not that impressed, so I'm looking for some advice. I've been playing with it for hours, but there's a good chance the problem is user error, so feel free to point me in a better direction. Here's what I've been doing to A/B it with the built in DI in my board:

    1. Rickenbacker 4003 into the 610, 610 output to a channel on my Mackie Onyx 1640. Mackie channel gain varies depending on how much signal I'm putting out from the 610 at the time. The meters on the mackie hover in the green/yellow range and occasionally hit the red very briefly, depending on how much 610 level there is (and I can only turn the mackie gain down so much).

    2. At the same time, I take a bypass signal out from the 610 into a second channel on the Mackie that allows direct input for guitars/basses, etc. Channel gain remains constant, since the bypass signal is always the same level. The meters on the mackie hover in the green-yellow range.

    So presumably I'm getting one channel coloured by the 610 primarily (with a little bit of Mackie influence) and one channel is pure Mackie. The performance on the two channels is identical. I play for a while, I adjust the 610 gain and level controls everywhere from way down to say 9 oclock maximum, first one, then the other, then both. I have to adjust the gain on the mackie as I go along so that the channel that is taking the signal from the 610 doesn't clip much of course, but other than that I'm not changing anything. Then I listen to the two tracks in my DAW, switching back and forth after setting their levels so they're equally loud on playback.

    After all that, I can hear a difference, but it is a very, very small difference. The 610 channel is slightly warmer, and I mean very slightly. No matter how much gain/level I push through the 610, the difference between the two tracks is so subtle that either (a) my ears suck, (b) I'm doing something wrong, or (c) the built in DI functionality on the Mackie is actually very good. Or (d) none of the above. By the time I get enough gain from the 610 to cause some distortion and make a real difference between the two channels, the Mackie meters are pinned in the red and the gain on the mackie is as far down as it can go on that channel. Although strangely, even when the mackie says it's clipping, the signal in my DAW is nowhere near clipping, and I don't hear clipping on playback (and I have turned up the mackie firewire output level control to close to maximum - but that's a separate problem, maybe).

    Anyone have any ideas what's up here?
  2. hueseph

    hueseph Well-Known Member

    Signal from the 610 needs to be XLR to TRS to go into line level input on the Mackie. Alternatively you could go into an insert. Gain on the Mackie should be set to unity. How are your monitors? The difference should be subtle. Don't expect it to do any magic. That's not going to happen.
  3. apstrong

    apstrong Active Member

    Hueseph wins the prize!* I was using XLR out from the 610 to into a XLR input on the Mackie. Why? I don't know. Best not to ask. Switched to an XLR to TRS and now the levels are much more manageable and I can dial in as much 610 gain as I need. You're right though, the difference is still subtle - a little warmth, a little clarity, more noticeable than when I was using the wrong cable, but not huge. I have to admit that for that price, I wanted some magic. Still, it's a nice difference, and if it makes mixing a little easier, I'm all for it. I'll hang on to it for now and try it out with some other instruments, vocals, snare, kick, etc., and see how it works out overall.

    *There is no prize. But he still wins.
  4. hueseph

    hueseph Well-Known Member

    You'll notice it more in the mix. Not such a big deal by itself but when you start stacking tracks, it'll make all the difference in the world.

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