unity gain

tayholliday

Hi! I'm trying to use my G2 Engine as a guitar effects processor (in the effects loop of my amp). Only problem is when I switch in the G2, the volume level decreases considerably, even when the input and output modules are at +6 dB and the patch level is set to 0dB. Is there something I'm missing?

I would think 0db for both input and output modules and 0db on the patch level would mean unity gain. As a test, I've just wired an input to an output in the VA section.

thanks!
- Taylor

varice · Posted: Thu Feb 28, 2013 10:50 am Post subject:

I believe the G2 system has some built in headroom on the audio output buss. This helps to prevent clipping the output when you have more than one slot producing sound at the same time.

One way to boost the output level of a single patch is to add more than one output module with the same signal connected. The signal will be summed on the output buss, just as multiple patches would be. This should be enough to get unity gain.

varice · Posted: Thu Feb 28, 2013 11:48 am Post subject:

Well, after a closer look, my suggestion of adding more than one output module does not really help. If you drive a single output module set to +6dB with a signal that pushes the VU meter to red, then you are pushing the output jack to the max.

Are you getting a good signal level indication on the input and output VU meters?

tayholliday · Posted: Thu Feb 28, 2013 1:35 pm Post subject:

varice, thanks for your help! That extra headroom makes sense.

I achieved approximate unity gain by adding in a Level Amp module. Now I must turn to the (probably harder) problem of determining why adding the G2 in the loop results in a somewhat unpleasant change to the tone.

varice · Posted: Thu Feb 28, 2013 6:55 pm Post subject:

Hmm… I haven’t noticed any problem using my G2X for processing audio input, but I haven’t tried it in a guitar amp FX loop. Does your amp have a buffer on the loop send? The G2 inputs are designed for line level instead of instrument level signals, and would probably not work well if the guitar amp FX send isn’t buffered. I use a Tech 21 SansAmp pedal as a guitar preamp to boost and buffer the signal for my G2X and that works very well.

tayholliday · Posted: Fri Mar 01, 2013 8:36 pm Post subject:

Yep, that was it. Thanks! I put a buffer at the beginning of the loop and all is well Smile

. Fortunately the GCX switcher I'm using has a buffered input.

Any idea why they build amps with hi-z effects sends? By the time you run the signal to a pedalboard and back its already lost of a lot of highs, assuming you're using true bypass pedals.

varice · Posted: Sat Mar 02, 2013 1:40 pm Post subject:

Apparently some guitarists argue that some pedals (I’ve seen fuzz pedals mentioned) sound better with a hi-z guitar signal. It looks like that philosophy spilled over into the design of the loop switch in your guitar amp. The amp designers maybe just decided to leave it up to the player to add a buffer if desired.

But, I agree with you. I think that the benefits of buffering outweigh any downside, especially for something like an FX send.