SOLVED - Out of tune when using JACK

[Mr. Lumbergh]

I'm having an odd issue with JACK. If I use ALSA as the backend for LMMS, notes play at their expected values when I'm using MIDI input or simply playing back a recorded track within the DAW but if I use JACK, the pitch is sharp by roughly a half step + 50 cents. For example, if I'm using ALSA as the sound server for the DAW D4 registers as a D on my guitar tuner, but with JACK it registers as an Eb sharp by enough to make the tuner almost register it as a flat F.
I'm unsure what could be causing this, is there some setting that may be misconfigured to cause this?

[Kott]

Wrong samplerate?

[merlyn]

Yes, a semitone and a half is what happens when a 44.1kHz stream is played back at 48kHz.

It's a difference of ~147 cents. I worked this out with the formula :

cents = 1200 * log2(f1 / f2)

[Mr. Lumbergh]

Good call, I didn't think of that. LMMS defaults to 44.1 kHz, but JACK was set for 48. Adjusted to 44.1 and playback sounds right.
Thank you both.