Does anyone use the Guitarjack 2 with MultitrackDAW?

[fgplayerx]

Does anyone use the Guitarjack 2 with MultitrackDAW?

I have some questions about the Mic/Line input and I can't find answers on their forums.

[dominicperry]

Yup, I use one occasionally. What do you want to know?

Dominic

[fgplayerx]

Hi Dominic, nice to read from you

As you might already have read in the Auria forums, I opened my Guitarjack 2 to look inside and found a AKM 4556vt chip inside. Which gave me a bit more confidence about the quality of the interface after reading the documentation.

But after testing it a while, some doubts started to come to mind. The first one was: is the mic/line automatic? Rodneybrown in the Guitarjack forums answered already YES. In my tests it is not. It does not detect a Line Level between a Mic Level signal and adapts. So, now I consider the PAD option in the control panel as LINE IN. And I adjust it. Between the PAD -12 and PAD -9 markings I achieve my best sounds using microphone INSERTS as SENDS from a Behringer mixer as source of the LINE IN.

So, I basically need the Guitarjack 2 as LineIn-AD-DA-LineOut converter. And it works quite well. Latency is not an issue for me when using the mixer to monitor. And my iPad 4 becomes a simple multitrack recorder during the recording phase.

I use Fourtrack to access the Guitarjack 2 control panel by the way.

But now, while testing and comparing Multitrack DAW vs Auria, I detected the next issue:
-If the control panel is set to Boost -12dB, both Auria and Multitrack DAW, respect it and use it like that.
-If the control panel is set to Normal -12dB, both Auria and Multitrack DAW respect it and use it like that.
-BUT, if the control panel is set to PAD -12dB, Auria respects it and uses it like that. BUT, Multitrack DAW resets it to PAD -0dB. Making me unsure which is the correct PAD setting being used. I have tried this on an iPad 4 with iOS 7. And with an iPhone 4S with iOS 8.

So, second doubt, does Multitrack DAW have a different handling of the GJ2? If you adjust the input levels in Multitrack DAW, is it hardware input gain or software simulated gain?

[pwnified]

Hmm, weird. About the only control we have as developers is checking if a hardware volume exists, and changing that hardware volume if it exists. MultiTrack will use the hardware volume if it's settable, and if it's not settable will fallback to software control. Here is the interface (from AVAudioSession.h):

/* A value defined over the range [0.0, 1.0], with 0.0 corresponding to the lowest analog
gain setting and 1.0 corresponding to the highest analog gain setting. Attempting to set values
outside of the defined range will result in the value being "clamped" to a valid input. This is
a global input gain setting that applies to the current input source for the entire system.
When no applications are using the input gain control, the system will restore the default input
gain setting for the input source. Note that some audio accessories, such as USB devices, may
not have a default value. This property is only valid if inputGainSettable
is true. Note: inputGain is key-value observable */
- (BOOL)setInputGain:(float)gain error:(NSError **)outError NS_AVAILABLE_IOS(6_0);
@property(readonly) float inputGain NS_AVAILABLE_IOS(6_0); /* value in range [0.0, 1.0] */

/* True when audio input gain is available. Some input ports may not provide the ability to set the
input gain, so check this value before attempting to set input gain. */
@property(readonly, getter=isInputGainSettable) BOOL inputGainSettable NS_AVAILABLE_IOS(6_0);

[fgplayerx]

I don't know if I can word this out. I'll try to explain how it works on both my iPhone 4S with iOS 8 and my iPad 4 still with iOS 7.

Ok.
So, to keep it simple, the Control Panel for the Guitarjack 2 will be set to BOOST mode at roughly 80% gain. And as reference, when you change the gain with the slider, you can hear faint "clicks" for every unit of gain that is changed. When the slider is moved towards 100%, the clicks get louder and vice versa.

When you are in Multitrack DAW. You have the option to adjust the line input gain. So, remember that we have the Guitarjack 2 at BOOST 80%.

So, again, inside Multitrack DAW, the default input gain is defaulted at 0.0 -which corresponds to BOOST 80% in this case-. If you attenuate the input gain, you can hear the hardware clicks for every unit of attenuation. You can hear them fainter and fainter while you attenuate more. That means that Multitrack DAW is modifying the gain directly to hardware. When you move the input gain back towards 0.0, you can hear the hardware gain "clicks" from fainter to a bit louder.

BUT, BUT, BUT, if at 0.0 input gain, you decide to add more gain, you don't hear any "clicks" at all. There is no added hardware gain. The BOOST mode stays at 80%. And the extra gain above 0.0 is simulated software gain.

I hope I could clarify this well.

[pwnified]

Sorry for the delay fgplayerx, I must have missed this post. I think I know what your talking about now. MultiTrack will control the hardware gain, if it exists, but the acceptable values for hardware gain are in the range (0.0 to 1.0), which correspond to (-inf to 0.0) in dB. So multitrack adds software gain to any value above that (0.0 to 12.0).