Leedh Processing- Unity Gain Settlng

Why would you want to pass the signal through the PASS preamp? My first instinct would be to turn the volume up to 100 on the PASS and adjust the volume with the Lumin

dznutz said:

Why would you want to pass the signal through the PASS preamp? My first instinct would be to turn the volume up to 100 on the PASS and adjust the volume with the Lumin

Click to expand...

Per Lumin’s instructions for scenario 2 (bypassing preamp volume control):

Scenario 2
Bypassing your pre-amp volume control
Scenario 2 diagram
Set your pre-amp to unity gain (refer to your amplifier's manual or ask the manufacturer about this - some have it labelled) and leave it there. Use LUMIN App volume to adjust your listening levels.

Leedh Processing is the default choice in this scenario.

I can only assume that this method exists for convenience sake, allowing you to sample the difference in sound between the two while not having to physically remove/disconnect your standalone preamp from the chain. I would think that optimal performance would be achieved by completely disconnecting your physical preamp when using Lumins Leedh volume control feature. Curious to hear if I am correct in my assumption.

Here are the 3 scenarios described by Lumin:

LUMIN - Leedh Processing

Appears I was correct... set your preamp at 100%

That’s option no. 1.

one of the reasons to run Leedh thru the preamp is to utilize it's extra outputs to subs.
Another is to add the "flavor" of the preamp. (possibly tubes)

Incorrect... In option 1 the Lumin is set at 100%... in option 2 your preamp is set at “unity gain”, essentially meaning 100% output in relation to input (as far as I understand it to be)

Hopefully Peter will step In to explain the various options including all Leedh and a combination of Leedh and preamp.

The idea of setting the amplifier's volume at 'Unity Gain' is to ensure that no volume adjustment is happening inside the amp - leaving Leedh as the only volume processing in the system.
There are many ways of doing this. Some are specific to the amplifier, but here are some general tips.
- If the volume display has positive and negative values and a '0' position, that is more likely 'Unity Gain'.
- If the amplifier has an AV-specific input and on that input volume cannot be adjusted, that is likley 'Unity Gain'.
- If the amplifier has a 'pass through' option and when this is activated, the volume control has no function, that is likely 'Unity Gain'.

Unfortunately not all amps have these and I've struggled on my own amp to find a position that is true unity gain. According to my manufacturer, it's when the knob is vertical, but this hasn't given me the confidence that it is truly unity.

Edit: See Peter's response below

For Pass XP-20.

Unity Gain: "You may also set any input to unity (0 dB) by setting the volume at step 75 from the remote or front panel control."

Pass Thru:
"
Input 5 is unique in that it is linked with the PASS THRU (Home Theatre) function

The theater “Pass Thru” function bears special attention, this function is only available as direct access through the hand held remote control.

[remote] PASS THRU: Pushing this button twice, sets the pre-amplifier to volume step 75 (0 dB) and input 5. As an added precaution when “pass through” is selected the volume ramps upto 75. This is to prevent nasty surprises when “pass thru” is selected accidentally. The ramp up sequence can be stopped at any time by hitting any button on the remote"

The advantage of having a preamp at unity gain is that it acts as a unity buffer. If it offers a higher output current it may be beneficial in some ways for some amps. (On the other hand, the native Lumin analog XLR outputs actually have lower output impedance than the XP-20 (1000 ohm).)