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Lower than expected line levels from my audio interface.

Discussion in 'Recording' started by jmm22, Nov 4, 2010.

  1. jmm22

    jmm22 Guest

    I was unsure of where to post this question, because it could have fallen in a few different categories. In any event, I have a new Saffire USB 6 audio interface. It sounds very good, but it is significantly quieter than other equipment. I have it hooked up to my Carver preamp, and from there into my Bryston 2B. The computer is the source for the Saffire. I make sure all settings in the chain are up to full, including monitor controls on the Saffire, however, when I toggle my main CD player with the Saffire, it is much quieter. Is this normal? Could my Saffire merely output lower line levels than my CD player? The quality seems fine, with a very good noise floor, and if I adjust my preamp, I can compensate, but it is a bit disconserting.
     
  2. hueseph

    hueseph Well-Known Member

    Have you checked the volume settings in your computer?
     
  3. dvdhawk

    dvdhawk Well-Known Member

    That sounds like a nice audiophile grade amp and pre for hi-fi, but it just sounds like you've got an input sensitivity mismatch.

    Which Carver?, Which Bryston 2B? [2B, 2B-LP, 2B-SST]
    Ableton that came with the Saffire, something else?

    Are you using the -10dB RCA outputs from the Saffire to the Carver?
    Some Brystons have balanced inputs, some don't.

    I'm not sure what you mean by, "The computer is the source for the Saffire."

    Can you provide some more details on the models and exactly which connections you're using?
     
  4. Boswell

    Boswell Moderator Distinguished Member

    I think the levels are what you would expect from the Saffire's specifications. The TRS balanced jack outputs are rated at +9dBuFS, but the unbalanced RCA outputs are only -3.5dBuFS (about -5.7dBVFS). This is low for an output that you would normally expect to have at least 12dB of headroom on a nominal -10dBV level.

    If you need to be able to switch the input of your hi-fi amp between your CD player and the Saffire outputs without experiencing gross changes of level at the amp, you may need to put attenuators (e.g. 12dB) in the CD player output leads.
     
  5. jmm22

    jmm22 Guest

    Thanks for the interesting and helpful replies. I did check all the volume settings in the computer. A few were down on the first pass, and I did net a bit more volume by bringing them up, but it's still shy. When I said the computer is the source for the Saffire, I meant that it is my DAW, and if I play a song that is on my computer, it goes through the Saffire and then into my monitoring system, i.e., the Carver and then the 2B.

    dvdhawk, the preamp is a Carver C-3. The amp is a Bryston 2B, one of the very earliest 2 rack sized units (1975 I believe), which of course initiated the appreciation for Bryston amps. I live 30 minutes away from Bryston (they are in Peterborough On) and was lucky enough to have them completely recap and refurbish it (rectifiers and all) and also add left and right level controls on the front, not long after I bought it, and for a very respectable price. The 2B does not have balanced inputs. My stand alone CD player is an Arcam Alpha 6, which is an older UK player that was highly regarded in its day.

    I guess I could run the Saffire interface into the Bryston, but to be honest, I like the switching capability of the Carver. It is actually a very clean and nice sounding preamp, so I do not worry about any possible minor coloration with it. It also has a direct CD switch that bypasses the internal electronics and thus plays the CD direct to the amp. dvdhawk, You did not ask about monitors, and I feel a little sheepish about boasting a touch, but given that the recording side of my hardware is so wanting for better gear (in the way of mics, DAW, plug ins, etc.) perhaps I can be forgiven for mentioning them. I have a pair of Tannoy GRF Windsor's, with 15" Dual concentric monitor golds. These are very large folded horns, and of course Tannoy's were used in many high end studios in the heyday of recording.

    I am using the RCA outs from the Saffire. I have Abelton Live Lite, but am using Cubase LE4 at the moment.

    Boswell, I am somewhat relieved to learn that the lower levels might be "normal" with respect to the lower output in this Saffire unit. I really do not need to be able to switch back and forth, so attenuators will not be necessary (at least right now). It looks like I might just have to overcome the weird feeling one gets from turning the volume knob up more than usual, unless there is a way to take advantage of the balanced outputs by somehow connecting them to unbalanced inputs?
     
  6. RemyRAD

    RemyRAD Well-Known Member

    There is also a situation with active balanced outputs that when unbalanced actually lose half of their drive capabilities & output levels. This generally occurs because one half of the active output is tied to ground in an unbalanced input to your preamp/power amp. This could also interfere with your level mismatch. I find it strange that the Sapphire's output level would be rated as low as Boswell indicates? WTF? For years we have had outputs standards that in the professional world have been +4dbm nominal level with headroom to at least +24dbm into 600 ohms. And on the consumer side it has frequently been -10 dbu into 10,000 ohms with a reference to a 1 volt 0db standard in comparison to a .775 V 0 reference standard into 600 ohms. So there levels are truly goofy. I just don't take much thought went into that? Go figure? And people keep barking about standards. Well that's not a standard. Perhaps standard in its confusion factor?

    What relationship to your differences in level, that is unfortunately a common occurrence when dealing with consumer grade materials/equipment. It can be incredibly frustrating when trying to evaluate differences in equipment. And it also makes it nearly impossible to interchange properly between pro-consumer & professional equipment with expected results.

    The differences make the differences
    Mx. Remy Ann David
     
  7. jmm22

    jmm22 Guest

    Hmmm... Something just occured to me. Maybe it has something to do with the fact that the Saffire USB 6 is solely USB powered. Maybe USB ports on computers cannot provide sufficient power, or maybe sufficient power draw causes problems (for the computer) that Focusrite wished to avoid. Then again, how does that square with the fact that the balanced out levels are higher?

    So, in practical terms, is this a nuisance issue (of having to crank up my volume level) or am I apt to find a real problem with the power defficiency? And is there any way to connect the balanced outs (that are rated higher) to unbalanced ins?
     
  8. jmm22

    jmm22 Guest

    "There is also a situation with active balanced outputs that when unbalanced actually lose half of their drive capabilities & output levels. This generally occurs because one half of the active output is tied to ground in an unbalanced input to your preamp/power amp"

    You lost me on this part. Are you saying this is a defect of sorts? How would I diagnose this as the cause, and is there a solution?
     
  9. Boswell

    Boswell Moderator Distinguished Member

    It's not a defect. That condition can occur when you are trying to feed a balanced output into an unbalanced input, and so it would only apply in your case if you were taking a lead from your balanced TRS jack outputs on the Saffire into the unbalanced RCA inputs on the amplifier.

    It you wanted to use the Saffire TRS jack outputs instead of the RCA outputs, you would get a level of +3dBuFS (you lose 6dB of the +9dBuFS because of unbalancing). This is still about twice the level available at the RCA outputs, but to get it to work you would need either to use a pair of jack-RCA insert leads, taking the "send" lead only of each channel into your amp, or, alternatively, wire yourself some TRS jack plug to RCA leads. Make sure you leave the "return" RCA plug on each lead or the ring terminals on your wired TRS jacks unconnected.
     
  10. RemyRAD

    RemyRAD Well-Known Member

    With my comment regarding the output amplifiers of balanced outputs without Transformers:
    Many modern day balanced outputs create the balancing act utilizing 2 Op-Amps. They work in a push pull like fashion when plugged into balanced inputs. When unbalanced, 1 Op-Amp output is simply tied to ground effectively removing it from the circuit. And with that, goes half of your potential drive capabilities. So output level is less. Headroom is less since it cannot drive its output level to its specifications since it is not loaded properly into the correct input source. And some balanced outputs by certain manufacturers indicate that one should NOT tie the "-" Op-Amp to ground but rather to not connect it at all. This scenario is not applicable to balanced transformer outputs as they suffer no level nor output loss when unbalanced. So active balanced outputs can actually be a mixed bag since all are not created equal. You must check with your equipment manufacturer if tying the inverting Op-Amp to ground when unbalancing into unbalanced inputs. Certain pieces of equipment can be damaged or produce absolutely disastrous sounding results if care isn't taken when you go from active balanced outputs to unbalanced inputs. Utilizing the insert scheme that Boswell indicates can be a viable option. Unfortunately, most inserts on most inexpensive common consoles are frequently lower in level & headroom than their output program bus brethren. Not true in my Neve which left no holds barred. That console is over engineered along with similar others like them. This cannot be said for most when it comes to utilizing inserts. You generally have to expect less output level from your inserts which could potentially cause you other gain staging errors in the process. But heck, most of the time it works out all right with most run-of-the-mill prosumer types of equipment. Lucky is the one who's inserts are potentially identical to the direct outputs which is not usually the case.

    I like to insert foot into mouth quite frequently
    Mx. Remy Ann David
     
  11. jmm22

    jmm22 Guest

    Thanks for the warning, and for all the other replies. I decided to solve this particular problem very pragmatically. I am ignoring it. Sure, I could fuss around trying to adapt the balanced outs to gain some power output, but wiring is not my forte. And truth be told, other than having to move my preamp volume more than usual, I do not sense any problems. The noise floor is respectably low (an order of magnitude lower than the brutally awful Firebox it replaced, which curiously had much more output) and I am happy with the quality of sound.
     

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