let me know if there is another thread for this, but I am wondering why plugging into my QC changes the sound (level and eq/character) SOO much even when I don’t have any effects on vs going directly into my amp. I have tried various input and impedance levels.
Definitely want to love the QC but this is currently driving my small brain very mad
how do you compare the QC to the amp? Do you place the QC directly in front of your amp, do you send the QCs output to your amps FX-Return oder do you use a dedicated power-amp between your QC and your cab (using the amp not at all)? There are many variables to “problems” like this, and it’s pretty hard to help without knowing them.
Hi David,
Thanks for your response. When I am comparing I have tried both the QC directly in front of my amp (a Supro Keely 1970 RK) and the 4 cable method. I don’t use a dedicated power amp.
I think the gain staging in the QC is perhaps not very well explained in the manual by Neural.
The consensus appears to be that it’s advised to have a strong an input signal as possible without clipping (i.e -10 to -12dB) aka consumer line level. This ‘seems’ to work well with all the amp ‘models’ and native effects (i.e. Facial Fuzz will not act like a normal fuzz face unless IN 1 LEVEL is set so the meter shows around this optimal level.)
However, when doing a capture, the IN 1 LEVEL has zero effect on the actual signal sent from the CAPTURE OUT socket. What I believe the IN 1 LEVEL is really doing is acting like an ‘audition’ control so you can match it to your IN 1 LEVEL on the main I/O screen. This will let you hear/audition you how your capture will sound in a preset. I’ve tested the signal from the CAPTURE OUT with a DMM (Digital Multi-Meter) and it stays the same no matter what the IN 1 LEVEL is set to. The reading I had was 1.774v (peak)/+4.979dB
Take a standard strat, for example. Plug it in to the QC and the IN 1 LEVEL meter on the I/O screen will show instrument level signal around -20 to -30dB (depending on the output of the pickups). To get this to the ‘optimal’ line level signal -10 to -12dB I’d need to stick up to 20dB of gain. So, say my IN 1 LEVEL is now set to +20dB. Then I go and capture my favourite amp/pedal and try to use it in a preset. The signal hitting the capture block in the preset is now way hotter than it would normally be just going guitar direct to the real amp. The capture GAIN control allows me 24dB of gain reduction so I’d need to use almost all of this reduction to get the same response as guitar to real amp.
It might just be me but I think when users are presented with the control set for a capture (Gain, Bass, Middle, Treble etc) it gives the impression it’s like the real amp’s controls as opposed to Gain staging and post-eq controls; or at least it’s not mentioned in the manual as such.
1 Like
I agree with this take. I was having huge noise issues with the QC on any high gain amps which was causing me a lot of grief. After trying all of the obvious things, cables, different guitars, gain staging throughout the preset etc i finally tried lowering the input gain. I only had it at 5dB (which raises the signal up to just below the red) but it was enough to add the noise I was looking to get rid of. I just keep it at 0dB and build the preset around that now. No more unwanted noise. Maybe obvious in heinsight.
2 Likes
So finally … what do you keep your input gain as ? 0 db or +20 db
I also use a strat
Input gain should be 0db. Otherwise you are altering the natural output of the guitar pickups to be different than if you plugged straight into an amp.
2 Likes
I typically keep it at unity and keep the volume at unity as well. I set my impedance one level lower than 1M (470k?) which works well with my setup/guitars. Essentially, you want your input to be high enough but lust lower than clipping. With impendence, it’s subjective. The lower you set the impedance level the end result tone wise will likely be loss of treble frequencies etc. Most set everything at default (unity) and are fine as well 
1 Like
This. If you want the models to react to your guitars signal as they are intended / designed to (i.e. like the real life counterpart) then let the input gain alone (at ±0db). If you want the models to be cleaner you can lower the input gain and if you want to drive the models hotter (like using a boost pedal before an amp in real life) then raise the input gain. But at 0db its like plugging your guitar into the real life counterpart of the models in your virtual signal chain.
I was having to apply +8db to get my already hot bass up to the suggested threshold for input. When using external pedals in the FX loop, I had to drop the send by -8db again or they’d just clip and distort like crazy.
Now I just leave everything at 0, and I’ve found that external pedals and captures just seem to work better all-round.
1 Like
Initially I boosted the input,
Then, I set the input to ± 0 dB, and my life changed
I’d like to say this was my experience as well.
I applied audio engineering ideas to the input and then realized NDSP engineers built the models with unity gain in mind, and that I shouldn’t boost or cut before the model unless I realize it changes what the model would do in a real-world scenario.
To make this a reality though, I had to make new presets in sets for all of my basses to accommodate one super hot bass I have, but this had other benefits as well (like optimizing amp settings and cab on a bass-by-bass basis)
1 Like
That’s the thing I feel NDSP could clarify…other pro audio digital gear has markings on the meter to suggest a nominal level of -18 or -20db (so you build in -18 or -20 of headroom)
And the QC input meter has a thin line that suggests a target they want you to be at.
But I think that thin line is a not exceed so you have headroom, but the devices (amp models, etc) are built for a nominal level 18db below that line.
Removing that line and then stating “amp models and captures are designed for 0db unity gain at QC input stage” might be a good idea. Maybe they already say that somewhere and I missed it.
2 Likes
I always had it at gain 0.
But after reading (probably here) that it should be set so when hitting hard, the signal gets around 0 in the bar, I’ve tried that setting a few times. I get more distortion in the same presets.
So I really don’t know what’s the correct setting, but I tend to thing it should be set closer to the line. I think I’ll make Copy of my main preset, which I did with the gain pot at 0, and will try to adjust it so it has the same level of distortion and see what’s the feeling.
Of course you get more distortion after boosting the input signal, as you would get from a real world amp after putting a boost pedal set to +XY dB between your guitar and the amp.
1 Like
I’ve watched some of those plugin input videos and leaving it at 0 makes sense but my tele barely registers on the graphic even when playing hard and my other humbucker guitar with a super distortion doesn’t do much better and both get cut off a bit prematurely by noise gates, no idea what people are using to get a signal near clipping without some kind of boost.
2 Likes
Curious if you ever found a solution to this?
Maybe your pickups are too far away from the strings.
1 Like
I’ve tried a bunch of things but something I noticed is weird input behavior after powering on when it has been left off for a while, really low input even when set high but adjusting the input kind of resets it, Maybe it has something to do with what is connected when it powers on, I’ll see if I can reproduce it. 
New video dropped on this subject
The TLDR is set interface gain to near clipping then reduce plugin input gain by the same amount you added so it’s unity.
Would the same thing apply to modelers? and if so should the QC/nano/plugins have some feature that automates this process? I know some plugin suites can automatically set an “optimal” level but it would be handy if you use different guitars.
3 Likes
Principally, this applies to the QC as well.
If you want to optimize the signal to noise ratio at the input, you can adjust (increase) the input gain (IO page) as far as you can without clipping. And then reduce it accordingly in the preset, for example by using a gain block in front of the amp model or the “In” gain in the preset.
However, with the standard gain on the IO page I never had noise problems with my guitars, so at least for me it’s not worth the hazzle.
3 Likes