Percussa micro super signal processor

A single-cable solution for connecting guitar via USB, as Brian Moore
Guitars began shipping this week in the form of their custom
iGuitar.USB axe, has a lot of appeal. But how practical would it be
to use a USB guitar onstage or in the studio? I talked to Robin at
the iGuitar factory headquarters to get some details.

CDM: What’s the resolution of the USB audio connection? Mono? Stereo?

Robin: It’s 16 bit, 48k sampling rate. [Apple] GarageBand maxes out
at 44.1, so that’s what it runs at there.

The audio stream is mono for a regular guitar, and stereo if the
guitar has the piezo acoustic pickups (guitar pickups on channel 1,
acoustic piezo on channel 2).

CDM: What’s the latency like using class-compliant USB drivers?

Latency is very good. I use a G5 iMac running Tiger and GarageBand, it’s not
noticeable, the spec is 3 ms. I have one tester running a XP/Guitar
Rig setup and got it down to 3ms also. So it’s VERY low latency, although
that number can depend on your system and applications.

If the class compliant drivers aren’t ideal for your system, or needs
more support, we’ve had some great results with the ASIO4ALL 2.0 DRIVERS,
www.ASIO4ALL.com
. But they aren’t necessary in most cases, and definitely
not on a Tiger platform.

CDM: What about the USB cable? The cable doesn’t lock in, so does it
slip out?

Robin: The cable does stay in pretty well, there’s no *locking*
mechanism but the jack is snug fitting and certainly wouldn’t just
fall out, you’d have to pull it out.

Keep in mind also, regular 1/4″ guitar cables do not lock either.
The amount of force needed to pull out a 1/4″ cable is about the same
as the USB cable, the USB cable may be just a little bit less snug,
but it’s close. The danger of a regular 1/4″ cable coming out during
a gig a very real, any player who knows this “locks” a cable in place
by twisting it around their strap – not high tech by any means. So,
this question could be asked of any guitar with a regular 1/4″ jack,
which is all of them.

CDM: Is this something people might use onstage, or is it really
intended for studio use only?

Robin: Our data so far definitely shows that the iGuitar will most
likely find the most use in studio/home studio settings.

It is certainly useable live, but the most limiting factor for live
use is the fact that the current USB cable length spec (universally,
not our spec) is about 18′ of cable. After 18′, you lose signal, and
after about 20′–25′, it’s no longer useable at all. 18′ is
generally not enough for most stage setups, when I play live, I am
sometimes using upwards of 30′ of cable. And this is in tiny clubs!
Forget about big stages.

But many people are using setups like this on stage with a laptop, most
notable right now is John Maclaughlin. If you’ve seen any pics of him, he
plays on
stage with his PowerBook right next to him. So in that case, 18′
of cable would be plenty. Also, I have many users and artists using
laptop setups for gigs, again, mostly small places, jazz clubs,
coffehouses, small clubs, and they have no problems, since their
laptop setup is generally no more than 5′ away, let alone 20′.

But, if we’re talking a punk band jumping all over the place, point taken, a
USB cable may not do . . .


Thanks, Robin! Readers, if you have more questions, fire away. I can say the pickups on these instruments are great; combined with the RMC jack for converting to MIDI (see our previous story), they’re also terrific for playing MIDI live. -PK