#1
Hey guys, just thought I would ask this question that really I have been dealing with for a really long time. My Shenandoah acoustic amp has a pre amp volume control as well as effects volume control. I have read the manual numerous times to ensure that I didn't miss something. Anyway I am kind of unsure where is the best place to set the pre amp volume or even what it does really. With an electric obviously you can push the amp and get distorted tones. So, maybe if someone on here has a similar amp you could shed some light on these controls for me and help me out.

By the way with the effects level I don't really see the purpose since there is a level for the effects next to the effect selector. And I have experimented with the amp but I just wanted to make sure I wasn't missing something.

Thanks in advance
Raconteurs Fan Guy
Last edited by COREYTAYLOR721 at Oct 17, 2015,
#2
The main point of having an onboard preamp in a guitar is to raise the signal above the noise floor. Assuming you want clean output, the guitar preamp should be somewhere between 11:00 and 2:00 o'clock, or about 50% to 70% on a linear slider. Otherwise, you can "clip" the preamp, leading to distortion.

On any amp with pre and post gain, you're going to turn the pre-gain down, and the post-gain up. And yes, that's exactly the opposite of what you'd be doing if you were playing an electric into the same amp. Plus, an active acoustic preamp, has a higher output than a simple magnetic pickup, hence it's easier to overdrive the inputs with your acoustic, than it would be with an electric.

As for the two different effects levels, I suspect one level may control the amp's onboard effects (1), while the other controls the level of the "effects send and return", (2).

I'm not familiar with your exact amp, but that's the way most of them operate


(1) You turn the amp's chorus on and set its level with that control.

(2) you would nook up your pedal board to the "send/return" loop, and control the overall level with the 2nd level.

OK, a lot of that is guesswork, predicated on the amps I have personally dealt with.

If you like, (and one is available), you could link us to your amp's online manual so we can sort out the particulars.

Part of the level adjustment parameters, is still going to depend on your ears. You need to be able to detect distortion thresholds, at least if you want to derive a clean acoustic sound.

Another point is, in amps with a clean and drive channel, you can set a low level grunge output in the dirty channel, and not have your acoustic feed back, yet sound like an electric rhythm guitar. An effect I like to play with doing Who tunes. Townshend uses clean to dirty (electric), quite a bit, in songs like "Behind Blue Eyes" on stage. I suspect that song was recorded using his J-200 and Les Paul, not one single guitar.

My point here is, you can accomplish the same thing, but reverse engineered, ,using just an acoustic at home.
Last edited by Captaincranky at Oct 17, 2015,
#3
Okay, so my amp is an acoustic amp both channels are clean. I just don't really see why there is a master and pre amp levels. So typically I put it at noon about. If you search "Genz Benz Shenandoah Jr LT manual" there is a PDF.
Raconteurs Fan Guy
#4
Quote by COREYTAYLOR721
Okay, so my amp is an acoustic amp both channels are clean. I just don't really see why there is a master and pre amp levels. So typically I put it at noon about. If you search "Genz Benz Shenandoah Jr LT manual" there is a PDF.
The pre-gain compensates for differential input volumes, for example an unamplified guitar pickup, and allows you to add a "bit of chug", should the mood or need arise.

Acoustic amps tend to have more in common with PA systems than electric guitar amps, and your amp is no different. So, try and think about the control system in that manner. It's like a mini mixing board.

The separate effects levels allow perhaps more reverb in the vocal channel than the guitar channel, or vice versa.

There is a pre-amp control for each channel, I'm not sure if there's any mystery to be found. So you plug your mic into one channel, and the guitar into the other. (Like a PA).