DI question (irig acoustic stage)

davecg321

New member
Hi

I've recently just bought one of these

IK Multimedia | iRig Acoustic Stage - Advanced digital microphone system for acoustic guitar

Its basically a clip on microphone (sound hole)

When I connect the output to a line channel on my interface the signal is significantly low, even with the volume maxed out on the 'acoustic stage' and the gain on my interface. However, if I plug into an instrument channel on the preamp I get a 'normal' healthy signal.

I read somewhere that you don't need a DI box when using an instrument channel on an interface/mixer. What confuses me is that from what I can fathom a Di box attenuates the signal rather than boosting it. So why the disparities on my line channel and instrument channel?

When using the irig acoustic stage in a live setup would I need a DI box or a separate preamp?

Regards

D
 
An instrument input generally has more gain than a line input, and it has higher impedance to cope with high impedance sources like magnetic and piezoelectric pickups.

Most DIs do attenuate, but since they have XLR output they are typically connected to mic preamps that have much more available gain than a line input.

For live use you might want a DI so you can connect to the system via XLR. Probably a decent quality passive DI would work just fine. There are exceptions, but the rule of thumb for DIs is use a passive DI for an active source and an active DI for a passive source.
 
Can't you just use the instrument input which appears matched to the device? The specs are a little bland - but although it says line level, it's probably instrument level as the pictures show it plugged in to guitar amps. The gizmo appears to be designed to be connected like a guitar? If your line level is expecting g +4dB it's going to be quiet.
 
Can't you just use the instrument input which appears matched to the device? The specs are a little bland - but although it says line level, it's probably instrument level as the pictures show it plugged in to guitar amps. The gizmo appears to be designed to be connected like a guitar? If your line level is expecting g +4dB it's going to be quiet.
I think of D/I's as impedance matching devices- not in terms of gain correction.
From IK spec..
Analog Output Connector : 6.3mm / 1/4" TS mono jack, line-level, low impedance
Analog Output Impedance: 50 Ohms (can drive long cables without any loss)
'Line level' ..you say. But no numbers. Hmm.
Pretty anemic for line level then given these problems?
Yet they portray them is ready to feed directly to mixer/pa systems?

What gives here?

Attacking from the other side, what interface (has no instrument level in presumably?
 
This makes more sense now. I had always planned to use the instrument input on my interface (presonus firestudio project) but was basically wondering why it was lower on the line inputs. From the tech spec it should be perfectly adequate with line level inputs right? (but clearly isn't)

Most gigs I play have a DI box of some sort. Although I guess it might be worth investing in something that may improve the tone. Any suggestions?

D
 
Most gigs I play have a DI box of some sort. Although I guess it might be worth investing in something that may improve the tone. Any suggestions?

I wouldn't worry about the tone unless the box they use is super cheap. I would do it so you always have one when you need it.
 
DI certainly are impedance changing devices, but the real reason for them is to sniff a range of inputs at varying levels, and output them as a microphone balanced output with similar output levels to a microphone. Most have extra cut options, but they're a device to reduce output, after all. Instrument level, as in guitar level instrument is a bodge really - now we've gone up in the typical line levels to +4dB, guitars are a long way down on that, after all. Most interfaces with instrument input also need the gain raised a fair way - so not the quietest things. I'm a stick in the mud kind of person - I don't include DI boxes in my list of sound altering devices. I know that transformers are favoured components - and us UK folk like Sowter, while the American enthusiasts have others like Jensen, and of course others like Lundahl. Me, however - I can't hear the difference. The Behringers I have sound the same as the BSS ones I have - to my ears.

My double bass pickup is way to feeble for a line input, but being high impedance, doesn't like a mic input - I get the impedance matching issue, but in my head - DI boxes are level matching devices first. A high impedance input is simply handy for not loading the source instrument, and of course bridging a pass through for a sniff connection.
 
Well, what I use them for is to take a high impedance unbalanced source and convert it to low impedance balanced output so I can run it down a long XLR cable without loss of tone or getting noise into the signal. The level change is a useful side effect that I could survive without as long as the input it's feeding has the gain range and/or a pad.
 
Poked around a little earlier as I never really paid much attention to the levels aspect.
The ones I've dealt with have input selection options -i.e. called a 'pad, or named for input type.
The one I pulled up w/o input options..
IMP 2 - Catalog - Whirlwind
indicated a -20dB 'level change'.
Just now noticed however this a transformer rather the active I'm more familiar with.
 
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