Hi everyone.

Two days ago, I installed jack on my mac, and since that, pd crashes regularly, stops reacting or just doesn't input/output anything: I guess I must have done something wrong in the setup.

So, if someone could tell me how to best configure jack and pd to work together (or point me to a link where that is discussed), I would be very grateful.

by the way, I also updated pd-extended to the current version just before installing jack, so it might even be a pd-alone-problem. But I can't tell, because I'm rather new to these digital audio issues.

The reason I installed jack in the first place was that I wanted to play around with my old electric guitar, using wavetables for distortion; it turned out that latency without jack was quite abominable; I then installed jack, and indeed latency decreased audibly. But for some reason, while yesterday everything worked, today it won't. (I admit I did play around with the audio settings of both programs, mainly sample rate and block size, to see how it would sound. Must have messed up something in the process.)

Another thing I noticed is that when I started up pd the first few times (yesterday, when it still worked) without having activated the jackserver, I got this message saying "you should start jackpilot now" or something like that, and it would allow me to start the jackserver directly from the pd window, more or less.
But if I start pd now without jackpilot activated, this message doesn't show up. This wouldn't be a big problem in itself, since I can activate it manually, but maybe it is a clue to somebody as to why pd now does not work anymore.

Well, I hope I could make myself understood, even if my post may sound a bit confused... anyway, thanks in advance for any help.

Just to be shure: are your audio settings consistent between jack and pd? I had problems when sampling rates, for instance, didn't match.

Yes, sample rate is consistent, but what else should I pay attention to?
Do buffer size (Jack) and block size (pd) mean the same? Should callback be activated?
By the way, although I still fail to see any clear pattern to pd's crashes or freezes, they seem to happen quite frequently when I open the audio settings and click any of the three buttons (apply, ok, cancel)... even withouth actually having changed any of the settings.
I also tried turning off the "hog mode" in jack, didn't seem to help; but I'll restart my computer now, maybe then something will have changed.

EDIT: That didn't really help, but I think I found a reliable way to get it running: The first time I startup pd-extended (jackserver already activated), it will stop reacting without even showing me the pd main window. However, in about two of three cases, in jack's connection manager, pd_extended_0 will then be listed in the receive ports (not in the send ports, strangely); if I shut down pd-extended (not pd!) via the osx activity monitor, the port will stay there as long as I do not shut down pd itself (which does also, strangely, not happen automatically); When I now start another instance of pd-extended, the jack connection manager will recognise pd_extended_1 as send and receive ports, and most notably, pd does react. (Yippie-ka-yeh, mezzoforte!)
And as long as I leave the pd's audio settings alone now, I can work with it.

Although it is quite a hassle, and I still don't figure what's wrong.

i had better results with "callbacks" checked, but that's on linux.

Just when I thought I had it working... it does crash again. So, since I want my stable pd back, I will now uninstall jack and pd and reinstall just pd, and see if these weirdnesses reoccur. Maybe it isn't jack after all.