I am looking for a versatile, hardware sound module to play with my Roland GK-enabled guitar. I want to be able to play my synth guitar, hear it without latency, and record it in Logic so I can use the same patches for editing.
Editor In Chief Paul White replies: I'm not quite sure what you mean by a sound module with no latency, as the very small triggering delay within MIDI sound modules isn't usually a problem. Guitar-to-MIDI converters inevitably introduce some delay because they take a fraction of a second to measure the pitch of the guitar string. But these days even those work so quickly that delay isn't an issue, unless you play at shredder-type speeds — in which case the thing probably won't track anyway! Some of the most responsive units on the market are Terratec's Axon products, which are compatible with Roland's 13-pin 'GK' pickup system. Having said this, I've had no problems with Roland's MIDI guitar synths (the GR33, GR20 and so on) when it comes to tracking speed. What's more of an issue with all these devices is the risk of finger noise triggering unwanted notes. You can usually avoid these if you play really cleanly.
Assuming the MIDI guitar interface has sounds built in, you can connect it to your computer's MIDI interface and hear sounds during recording and playback. Make sure you switch the synth module to 'local off' and connect both its MIDI input and output to your computer's MIDI interface. If you want to experiment with some of the soft synths or the EXS24 sampler in Logic, there will be some latency depending on the buffer size. (This can be set in Logic 's Audio Hardware and Devices menu.) If you can set the buffer to 128 samples without the system losing stability, then the latency should be too small to worry you, and if you are playing sounds that have a slow attack, you can get away with an even bigger buffer size before you notice any delay.