Problem with AB box and Y box

Hello,
I want to plug my aeros in a quite strange way and I need help to understand why is it not working.

Here is the signal chain :
Guitare → AB box
A → looper → Y box → Amp
B → Y box → Amp

When the AB box is in the A position : no problem, it’s the normal way to use a looper. The guitar signal go to the looper, and then go to the Amp. I record a loop and it plays normally.
The Y box (between the looper and the Amp) receive only one signal from one of its inputs (from the looper). The input linked to the B of the AB box is unconnected from the guitar (because the AB box is on A position)

But when I swith to the B position, THE GUITAR LEVEL BECOME LOWER, while the LOOP level is still the same. Strange no?

And even stranger : when i add some effect pedals between the guitar and the looper, it’s not the GUITAR level that become lower but the LOOP level !!

It shouldn’t change because in the B position, the Y box receive 2 inputs : the loop previously recorded on the looper, and the direct sound of the guitar (without passing through the looper)

How can the guitar, when going directly to the Y without passing through the looper, can affect the level of the loop signal that is already recorded in the looper?

Anybody have a clue?

Thank you!

Hi Olivier,

Thank you for providing all those details! To help me understand the setup better, could you please record a short video showing the devices, the connections, and the signal chain? This would be really helpful. You can send it to support@singularsound.com, and I’ll do my best to resolve the issue for you.

Please also include this reference in your message: Problem with AB box and Y box.

Thank you!

It sounds like the problem comes from the passive Y box. When your guitar signal goes through the Aeros looper (path A), the looper’s buffered, low-impedance output keeps the signal strong. However, when you switch to path B and bypass the looper, the guitar’s high-impedance signal goes directly into the Y box, which can cause a noticeable drop in volume when summed with the looper’s low-impedance signal. Passive Y boxes don’t provide the necessary buffering or isolation, which is why the guitar signal gets attenuated.

To solve this, you could either add a buffer between the guitar and the Y box in path B or switch to an active Y box, which would maintain both signals at their proper levels without causing volume loss.

Somebody more knowledgeable may chime in with more precise info, but I wanted to point you to look into active Y boxes (such as the JHS Summing Amp), although I don’t understand why you would want to bypass going into the Aeros as I think your signal will benefit from its buffers and low impedance output.

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