Reaper Daw help

Not a Reaper user, but the pan law/s implemented within DAW's differ. All should have an option to choose your preferred pan law, but unfortunately most (IIRC) don't.

So, I'm speculating that the one you're using, whether it's the default / changeable or whatever in Reaper, is one where level is reduced at hard-pan settings; the amount deducted is scaled up as you pan harder. I've not heard of such a law as the convention is to reduce level as you approach the centre 'cause the signal is now coming from 2 speakers, but if the laws in Reaper are customisable it's possible someone (you, by accident?) has inverted the normal behaviour.

Here's what Wikipedia has to say about it; it's instructive even if it turns out not to be the issue:

Pan law, or pan rule, is a recording and mixing principle that states that any signal of equal amplitude and phase that is played in both channels of a stereo system will increase in loudnessup to 6.02 dBSPL, provided there is perfect response in the loudspeaker system and perfect acoustics in the room.

Often, the acoustic summing of a room and system are much inferior to the ideal, so the specific relative level will change from −3 dB to 0 dB as the mono signal is panned from center to hard left or right, and this sounds natural. The idea is that when one directs signals left and right with the pan pot, the perceived loudness will stay the same, regardless of latitude.

However, both the direction of attenuation throughout the panoramic sweep and the amount by which the signal is attenuated vary according to pan rule. For example, the Yamaha digital consoles employ a typical (compromise) 3 dB pan rule, however, the signal is at full level at 12:00 and becomes progressively louder (up to + 3 dB) as it is panned to the right or left.

The 3 dB pan rule is a commonly applied compromise to comply with the mediocre acoustic summing capabilities of most control rooms. However, the console manufacturer SSL used to employ a 4.5 dB pan rule, because it was believed that their expensive consoles would normally be used in tuned rooms that had acoustic summing capabilities closer to the ideal.

Many consoles that have only one pan rule employ one such that a signal panned hard left or right is at full level and becomes progressively lower in level as the pan is directed to the center.

According to mastering engineer Glenn Meadows, the Kinoshita-Hidley rooms at Masterfonics (Nashville, Tennessee), produce close to 5.9 dB acoustic summing when both loudspeakers are presented with the same in-phase signal.

Crumpets! Even I am amazed by the accuracy of my guess, mate. The mojo is with me today.

So glad you're now sorted. Maybe you can set your preferred pan law for a "template" project, save that, and use that from now on?

If you're on Mac there's a trick:

Command-I or "get info" for your project file.

You should see two checkboxes near the top of the pop-up window - "Stationary pad" and "Locked".

Clicking the "Stationary pad" box will mean that when you load your project, Reaper will work from a copy of the file, not the original.

Quick video explaining "Stationary pad" and "Locked":

Quote from Rapidfire

With Reaper you have to set the pan law for every project. Just in case someone else has this issue

What setting did you end up using for the pan law?

If you mean -3dB when centred / + 3dB when panned-hard, that one's the way to go IMHO.

I didn't know anyting about Pan Law!

I've just discoverd that Cakewalk has 6 different options to choose, but expecially that Kemper ''Panorama'' knob in Rig Settings add +3db if you hard pan L or R (+5 or -5 values)

thanks Monkey_Man