ARTEC QTB Onboard Booster投稿日: 3月 25, 2013
The idea of a battery dying or going dead in the middle of a performance is enough of a reason that most guitarist think active electronics are a terrible idea. Besides the impractical logistics of unscrewing your pickguard in the the middle of a gig, the conventional wisdom is that the guitar gods of the 60s didn’t have active electronics, than we don’t either. Elder pickup guru Bill Lawrence was quoted as saying “Batteries belong in flashlights.” However the reality is that bassists and acoustic guitarists use active systems all the time, and so do heros like Eric Clapton, David Gilmour and BB King, not to mention lords of metal like Metallica and Zack Wylde. So why do we electric guitarist still shy from them?
Some time ago, I became interested in the idea of an on-board buffer to save space on my pedal board. There is really no way to easy way to mount such a device inside my GB-10, and I never really felt it was necessary with my G&L Legacy’s control circuit. So I got a Dan Armstrong Orange Squeezer. However in my search, I found the Guitar Fetish website. After months of browsing, and finally I decided that I needed a solo boost for jam session where setting up pedals on stage is awkward and kind of embarrassing. However when I tried ordering, they wanted me to fax a copy of my credit card an ID. Not wanting to be bothered, I found the same part here in Japan sold under the Artec brand for the same price.
The circuit I ordered is the QTB, which is a rotary switch providing +3, +14 or +20db of clean boost, which is enough to overdrive any amp. They also make an onboard distortion circuit for which I had zero expectations, but how I would have wished for one of those on the first electric guitar I got when I was 11 years old. The mid-boost circuits the make I imagined would just make the sound muddy and inarticulate. The QTB also colors the tone slightly. There seem to be a little less highs and lows, kind of like a tube-screamer. Rumors that these cheap Chinese preamps are noisy are exaggerated. In the buffer setting (no boost), there is no additional noise. At the 20db setting, extra noise is inevitable.
Installing it was a bit of a challenge, but I took my time and completed the procedure in about 3 hours with only one mistake which I noticed early on fortunately. I was afraid there would not be room for the battery and had to put it in between the neck and middle pickups with some tape to hold in in place. Also, the stereo jack required for operation is a bit of a squeeze in the jack cavity, but it doesn’t make any popping noises when plugging in and turning on. The biggest challenge was mounting the control pot. The shaft was slightly narrower than standard sized pots, and the normal nuts didn’t fit but I used one anyway to secure it snuggly onto the pickguard.
My only complaint about this circuit is that I loose the tone control for the bridge pickup. I was using different values for each: 47nf for the neck and 10nf for the bridge. Since I now only have single tone control, I decided to compromise and use a 22nf cap which doesn’t really sound good on any of the pickups. So I may just try the 10nf instead. Also, I noticed that the bass cut has hardly seems to have any effect with the booster engaged. So spent the weekend messing with the wiring, mostly failing. However, at least I have a more palatable treble-bleed now with a 1000pf ceramic cap in parallel with a 150k resistor. Right now the guitar sound mellower, but the tone control does not seem work at all.
It’s also possible that the harshness is just because the pickups are too close to the strings, but if I lower them, the high-E will be weak. So I’m actually considering swapping the Keystones with a $21 set of no-name Chinese pickups with 50mm spacing and about the same impedance as the original Duncans. As for the QTB booster, I like what it does for the sound, but the operation is a bit awkward and redundant. That’s what pedals are for, right? A better strategy would be just to play the guitar with the volume rolled off slightly, and then dime it for solos. This would also capitalize on the treble-bleed’s bass cutting properties. Likewise a good TS-style pedal should do that for solos, as well.