Hydrogen drum kits, audio latency, jack crashing

I've been recording a bit in Ubuntu 8.04 (Hardy) using Ardour and Hydrogen, a splendid drum machine / sequencer. The audio interface is, as I have mentioned, an Edirol FA-66.

Hydrogen drum kits
It's been a while since I last checked the list of Hydrogen drum kits, so I was pleased to see that there are more than the few I knew of. You can find them here:

Officially distributed drumkits
A blog post with a bunch of different kits
Asma Davul, a turkish drum

The blog post above actually links to a drum kit I made called Aqoustic. It was a first attempt, using samples of a friend's drums. Not very high quality. The blogger calls it "another homemade jobby". Urban Dictionary tells me "jobby" is scottish for poo. Fair enough!

Audio latency
I have been using jack in real time mode with a buffer size of 512kb.

One thing I've noticed that's different from when I recorded with a mere SoundBlaster Live card on my desktop computer is that the latency between different programs seems to be gone. When syncinc Ardour and Hydrogen for recording drums, I don't have to trim the resulting audio region, which I needed to do before because of the lag.

When recording from an external source - in this case: electric guitar through a Boss ME-50 - the latency varies. Sometimes I seem to get minimal latency, again with no need to trim the recorded audio. Curiously, when I turn up the monitor mix knob on the FA-66 to hear what I play while I record, there is a noticeable latency.

Jack server crashing
After a while of doing takes on several tracks, the jack server crashed. Not with a bang, but with a whimper. Qjackctl froze and Ardour reported that the connection to jack was lost. When trying to restart it, I got an error message (which I will paste here later). This latter error was resolved by resetting the firewire bus using a program called gscanbus and then starting jack. However, it didn't take long before jack crashed again. I will have to find out what causes this problem. I have yet to try different buffer settings, maybe that will give me something.

I hope it's not a hardware issue. I have decided to buy the FA-66, although I haven't been able to test it first as much as I had hoped to. I have done little recording with Ableton Live in Windows, and I didn't notice any anomalies then. This should mean that my problems in Linux are solvable.