Proper level for input?

Started by Petros_k, February 21, 2024, 05:06:13 PM

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Petros_k

Roland/Boss offers very little info on the proper level you should be getting to record in. Bottom of page 8 in the manual only shows a vague illustration suggesting where the meter should be. Leaves lots of questions. For example, is that input level peak, RMS, or what?

 
I wanted to share how I worked this out but got odd results. To start, with no looper connected, I set up my pedal board (which includes a Digitech RP360 digital effects unit) so that master volume had some headroom (up only about 70%) and most importantly, the audible volume when effects were engaged was about the same as when the effects were bypassed. That roughly got me unity gain for a baseline without the looper involved (to be sure my effects were not creating too much gain).

There are two options available on the RC-600 for the 2 instrument inputs, line level and instrument level. After going through the above procedure and connecting the RC-600, I found the line level option on the RC-600 input setup was much lower in audible volume while the inst. level was about the same. That tells me with input set to instr the device is likely working in the neighborhood of -10 dBu for an unbalanced signal, which would be appropriate if plugging into the front end of an amplifier as I do with guitar.

Problem with this is despite my attention to unity gain, the input level on the looper is showing me not enough level for recording purposes, and I barely get the meter to register at all. But the question is: Does it really matter? It still sounds great. I hear no evidence of a poor signal to noise ratio. Still, it bugs me that the RC-600 input meters suggest something is wrong.

If anyone knows the meters need to be registering somewhere closer to the 100 mark like the manual illustration suggests, please share. I have yet to consult Roland on this.

gumtown

I don't have that particular device, but in general for Boss devices, I set the input level so the peaks are at 75~80%
The Boss gear has quite a large amount of headroom at 24bit, so it is not too fussy on levels.
Free "GR-55 FloorBoard" editor software from https://sourceforge.net/projects/grfloorboard/

Petros_k

The Boss RC-600 is doing 32-bit AD/DA conversion, not 24-bit.

What I can't believe is right is when I increase my master volume to the point I get maybe a 50 - 75% input meter level on the RC-600 it's insanely loud. It sounds like it's on the verge of clipping, or maybe already clipping. And I can't just switch from an instrument level (which has the most gain) to a line level for input on the RC-600 because that of course drastically lowers the input level.

Again, trying to go with what sounds right after paying close attention to unity gain. I might try going into a DAW with the looper and place a meter before and after it to see if I can detect clipping when the input level meter on the RC-600 is registering about 75%.

Petros_k

Here's the response I got from Roland customer support:


Sorry to hear you're having issues.
When having input and output volume issues, we recommend removing as many variables as possible. Please use ONLY Instrument into RC-600 and RC-600 output to a clear amp, PA system OR Headphones.
 
If the input signal is distorted, please check your input signal before connecting to the RC-600 to determine the source of the issue. This is AFTER you've already used ONLY GUITAR OUT > RC-600 INPUT and Headphones.
 
We do not have an answer to any of WHY the control is set to turn to 200. We support only operational issues with your unit. Furthermore, we do not build or create the GUI of these units, as you're speaking with the Product Support/Customer Service team.
 
We do not have a procedure dedicated specifically to input and output level because the output and input device can vary from user to user.
When adjusting input and output level, we recommend leaving the output volume low, setting the input level to the default minimum from the factory (usually 100) and then slowing bring up the OUTPUT level slowly until the desired volume is reached.
 
The number correlated to max and minimum output/input levels allows users to flexibly mix their instruments. This depends on the instruments connected.
We would say to not have the volume at the absolute maximum but somewhere in the middle.
You can quickly navigate to the MIXER window by pressing the ENTER button when looking at the home screen.



That's the second response I got from the same person, and I can't exactly make heads or tails out of it. It's as if the person is intentionally not giving me a clear answer. Even this statement:

We do not have a procedure dedicated specifically to input and output level because the output and input device can vary from user to user.

That suggests there is no "proper" input level despite what the manual attempts to show on pg. 8

Elantric

#4
Find the I/O  settings to obtain unity gain on any device

Get two passive A/B switches
One at Input, one at Output
A/B switch both input and output

Compare the unit under test vs  a straight 1/4" guitar cable -

Adjust the input and output of device under test to achieve identical signal level as the straight cable.

IMH1234

How are the output levels set? I am not particularly familiar with the RC600 but assuming there is not a fault in the device then what you describe sounds like the output level is maxed out and you might get better results setting input level higher but attenuating at output?

Another possibility is that the looper is outputting line level into an input expecting instrument level.

Petros_k

#6
Quote from: Elantric on April 09, 2024, 03:33:55 PMFind the I/O  settings to obtain unity gain on any device

Get two passive A/B switches
One at Input, one at Output
A/B switch both input and output

Compare the unit under test vs  a straight 1/4" guitar cable -

Adjust the input and output of device under test to achieve identical signal level as the straight cable.

I actually tried something like this, but not using an A/B switch and instead pulling out the cable into the RC-600 and just sending it to my amp. There are some fundamental problems with this too:

1. Where should the main output of the RC-600 be? --100, assuming that means 100 percent output? The Roland rep answering my questions above said he could not explain why does the main output go to 200. ("We do not have an answer to any of WHY the control is set to turn to 200.")

2. When I tried doing this assuming I could put the RC-600 main output at 100, I used the gain on a Digitech RP360 effects unit to get the output of the RC-600 through the amp the same as when I just go from the effects unit to the amp. Sounds fine. But again, input meter for the RC-600 is not registering as if the input level is too low. 

Is it safe to say simply if it sounds okay then just ignore if the input meter is registering or not? What I'm risking is the input level is too low, which means potentially bad signal-to-noise ratio at higher amp volumes and also potentially less output volume available. 

Petros_k

Try to understand what I did today to check this again:

I ran a guitar cable straight from my guitar to my amp and noted the level. I then connected the guitar to an RP360 effects unit and set the master volume to get me about the same level. The master volume goes to 99. I achieved what sounded close to unity gain at 70.

Then I connected the effects unit to the RC-600, setting the input for "instr" (not line). I then put the main output knob at 12 o'clock, which the display shows is 100 (if all the way up it goes to 200). 

At this point, what I hear out of the RC-600 is the same as what I hear from just going out of the effects unit into the amp. That should mean I've got unity gain with the RC-600.

-BUT, when I look at the input meter on the RC-600 I don't get it registering at about half the length of the meter until I turn it up to 130, which obviously now makes it also sound much louder. It doesn't quite sound distorted, just louder as expected. Of course, I now need to turn down the main output knob below 100, but that shouldn't be an issue like getting an input level so that the meter registers.

Is that it? Should I stop there? Just leave input level at 130?

My question to Roland was basically: Is this what I should be doing so that the input meter registers as it shows on pg. 8 of the manual? Because following my procedure I'm not sure why I need to turn up the input level to 130. The answer from Roland was that there is no "proper" way to set the input level, which kind of contradicts pg. 8 of the manual and leaves me guessing am I making a mistake.

Ultimately, what I'm trying to avoid here is recording a whole bunch of loops at a poor input level and then needing to re-record everything again. When I was using the RC-500 I had no concern for this because that unit does not have a meter display, only a color-coded LED indicator (green=low, orange=suitable, red=high) and you are supposed to set input level so that the indicator is occasionally going into the red. With other loopers I've used in the past made by Digitech I also had no concern for proper input level. But with the RC-600 I was under the impression there is a proper input level to get the best recording onto a track.

And there's also one more meter on the RC-600 if you go to the mixer display: a "loop out" meter, and you can see that as you add tracks the level gets closer to 100. This level can also be adjusted, but default is 100. What I discovered is when the main output is at 100 and loop output is at 100, the level meters indicate main out equals loop out. But again, this doesn't concern me like what should be the proper input level to record onto a track. I can turn down the main output knob below 100.

It appears that the lower your input level when recording the tracks the more headroom you'll have at the loop output meter. But is the loop output meter "overloaded" if it exceeds 100? So far that's not a problem with me but I guess you could just turn down the loop output level.

IMH1234

Quote from: Petros_k on April 11, 2024, 04:31:13 PMIt appears that the lower your input level when recording the tracks the more headroom you'll have at the loop output meter. But is the loop output meter "overloaded" if it exceeds 100? So far that's not a problem with me but I guess you could just turn down the loop output level.

Sounds like you have your answer right here. A simple rule of thumb for proper gain staging - use input gain to get an optimum signal inside the unit and output gain to set the level going into the next device. Do this and 95%+ of the time you will get the right answer

Petros_k

#9
Quote from: IMH1234 on April 11, 2024, 10:11:05 PMA simple rule of thumb for proper gain staging - use input gain to get an optimum signal inside the unit and output gain to set the level going into the next device. Do this and 95%+ of the time you will get the right answer

I hope you're right. But why didn't the rep from Roland say something like this? Instead, he said:

When adjusting input and output level, we recommend leaving the output volume low, setting the input level to the default minimum from the factory (usually 100) and then slowing bring up the OUTPUT level slowly until the desired volume is reached.

That's not what the manual says on pg.8, which directs the person to look at the input meter and try getting a similar level. Moreover, they are showing the level at 90, which suggests you should be turning down the input level not leaving at the default 100. He also called it the default minimum.

In general I think it's probably not as critical as I thought to get a "proper" input level beyond making sure you see the input meter is registering about halfway up the meter length and then checking the loop output meter if you run multiple loops at the same time just to be sure it's not peaking. Then adjust the main output for a comfortable listening level.

I still say anyone using a pedal board needs to be careful if your signal chain places the RC-600 last right before your amp. After you record 3 or 4 loops you could be unaware you're overloading the loop output.