My speakers are time-aligned by design, so tilting would ruin that. I haven’t tried.
But I suspect that unless your speakers were designed that way it might not be the best idea. Perhaps first try to listen (and measure if you have the tools) off-axis by the same angle as you plan to tilt them, to see how that changes the frequency response.
And of course, assuming tweeters are ear-height, by tilting the speaker the angle of the mid moves towards on-axis.
All-in-all I do wonder to what extend it would work if your speakers weren’t designed that way to begin with, but do let us know. It’s an interesting experiment.
I have my Keilidhs tilted back as far as the spikes will adjust front and rear. Helps mitigate the low position of the tweeters. From what I remember when experimenting, the faff all seemed worthwhile.
I design & build my own speakers and I discovered the positives of time aligned baffles a few designs ago, especially so with 3 way floor standers.
It’s a big positive for me as I’m listening fairly close at 2.5m.
But I suspect it becomes less of an issue with greater distanced listening positions.
Always fun to try
For time aligning some manufacturers use stepped baffles, others build time delay into the crossover. When I was tri-amping the active crossover allowed precise timing adjustment between drivers.
As for tilting, when I was first considering the PMC MB2 (then as SE version), i thought about dispensing with the stands that raise the speaker so that ear level is about between mid driver and tweeter, instead lowering and leaning back to point up at the listening position. The intent was purely to lower the speaker top by at least 30cm, so that if in front of the window they’d be less intrusive. No change to time aligning in that case as the distance from each driver to ears would be about the same as when on their supplied stands, so I hoped no change to the speakers’ characteristics.
I don’t think necessarily so, if you aim so that at the listening position ear level the axes pass your ears the same height as if as originally - but would only work with stand mounted speakers with new stands lower (or of course higher for downward tilt, also possible with floorstanders by adding a stand). It would just be as if listening live from a higher (or lower) seat.
If the off axis response is acceptable and you don’t tilt them more than the respobse relative to your listening position can support, it’s not an issue.
You won’t gain any time alignment benefit as this will already be built into the design. Tilting the speaker doesn’t change the drive units’ stop point relative to each other, only relative to you so you may actually introduce smearing. You’d have to change the construction of the cabinet to really change the driver relationship, not merely tilt the speaker.
Some speakers are designed to be forward or tilted. JBLs tend to come with optional flat or leaned back cradle stands. As mentioned already, PMC TwentyX speaker use the slanted cabinet as a bit compromise. It only work for time alignment because they have very wide off axis response and the drivers are high up near an average seated ear level. Let’s them build a simpler crossover and deliver great performance at a price point but with some tradeoffs (hence the higher end models don’t do it).
Ultimately though, unless the listener has their head in a very small bubble in the sweet spot, mucking about with the alignment isn’t going to be a game changer because the listening position deviated more than any potential non alignment ever would.