Tascam Model 12/16/24 Metering and Levels

[au4reel]

Hi, I recently acquired a Tascam Model 12 recorder/mixer and am trying to figure out how gain staging and levels work on it e.g. what units and metering do the LCD meter and LED meters read in. Side note, all of this was realizing that the values on the LCD and LED meters did not match 1:1 when gain and faders were set at unity.

A few things to note:

-Tascam makes a point that the line on the LCD meter represents a value of -12db in the manual. I wish they would have discussed more how the meters/levels work.

-There are several great videos on YouTube on using the Tascam Model 12 and they make the point that the -12db on the LCD meter is a good level to hit when adjusting the input (preamp gain); Tascam never explicitly says this (unless I missed something) but it makes sense since that’s generally a good level to aim for when recording.

-Those same videos also suggest that the LCD meter is a digital peak meter ranging from approximately -40db to 0db, again the line represents -12db. They also point out that the LED meter is basically a VU meter. These also seem to be fair assessments.

-Lastly, I read on a forum (in response to someone who was also confused with the meters and levels on the Tascam Model 12) that 0db on the LED (VU) meter equates to -15dBFS

After studying these points, I’ve made a few assumptions but am not sure if they are correct:

1. The LCD meter is a (digital) dBFS meter and the LED meter is a VU meter (units can be equated to analog dBu/dBv units, so 0 VU is about +4dBu—assuming that these are the actual units)
2. This would suggest that the -15dBFS value on the LCD meter would be the nominal level and -12dBFS is good for setting levels when recording and provides decent headroom; note that the VU meter would read about +3dBu (again assuming those are the units)
3. If my above “conclusions” are correct than it seems that Tascam is breaking a bit from standard reference levels between meter types i.e. +4dBU (analog) = 0VU (analog) = -18dBFS (digital) and instead using there own where +4dBu (analog) = 0VU (analog) = -15dBFS

Lastly, I did reach out to Tascam Support and they wrote this, which confused me a bit more: “
That information is not in the owner's manual or the specifications. What I would advise you do in order to achieve the best signal to noise ratio into each of your channels when you record, is to use the gain knob and make adjustments by turning it up until you see the green LED start turning RED as this indicates the point in which distortion starts to occur.

You don't want to use the line in the middle as a reference point to just reach as this is the nominal gain (0dB) point and there is still headroom to be used above that line. Use the SIG LED at the top of the channel strip as your reference to know where the point of distortion starts to occur. You will get much louder recording levels as a result.”

I am not sure how to support team member can say the LCD meter line is 0db when the manual says that it is -12db (likely dBFS), I do wonder if they were referring to the LED (VU) meter since they suggest that the 0db value is a nominal level which is usually understand as being 0VU (not 0db). I still think that the -12db (likely dBFS) is a good target to hit on the LCD meter as this typically good recording practice and this typically reads as 0VU if everything is set for unity gain (channel gain/faders).

I tried to study the levels block diagram in the back of the manual but quickly got a bit confused and I don’t believe it does elucidate much or any on my questions.

Am I remotely correct or up in the night, thoughts and opinions appreciated!

 

[Mark Richards]

Welcome to the community, @au4reel.

I'm not an owner or user of the Model series, but it seems to me you're overthinking this.

Looking at the Block Diagram, the Model 12 operates completely in the digital domain. That means no VU meters, which are applicable only to analog circuits.

So everything on the Model 12 is measured in dBFS. There is no analog equivalent.

-12 dBFS throughput is an optimum level for recording so long as the input circuit isn't overdriven (that pesky red overload light). The OM addresses that in a very straight forward way, from what I saw.

There are sticky posts (Equipment Tips thread; Production Tips thread) in the 2488, DP-24/32/SD digital portastudio forum that may help clarify analog v digital metering, signal flow, etc.

 

[au4reel]

I can see your point but it does seem like Tascam possibly intended the LED meter to be used like a VU meter given that it’s range goes from -30db to +15db (not counting the labeled “OL” level) as one would expect for a VU unlike a digital meter where 0db is the max (distortion level) such as the case with the LCD meter, so it appears. Also from what I understand, the Model 12 has analog preamps after which the signal is converted to digital.

 

[Bravin Neff]

Tascam are likely being inconsistent by having the LED meters have a "0VU" level (-15dB from peak) different from recording nominal level (where the line is at -12dbFS). It is better to ignore Tascam and just record "properly," but that has a little grey area...

Proper level settings is something that is lost on, frankly, most people. But to their favor, 24 bit recording allows so much flexibility and dynamic range that you can have levels (and many people do) wildly off from "proper level" and it still comes out totally fine.

I'm not saying this out of thin air. This confusion is so widespread it even permeats the multitrack manufacturers themselves. How do I know this? Because I have many manuals from the late 90s and early 2000s of multitrack recorders, where *the manuals themselves* explicitly tell you to "record as hot as possible without clipping" as a level-setting procedure. Here is a direct quote from the Yamaha AW16G recorder: "For the best audio quality, adjust the level as high as possible without allowing the meter to clip when the loudest volume occurs" (page 34 of AW16G Owner's Manual). This would imply level setting as hot as, say, -6 dB, or even hotter, depending on the source.

There is also dispute on "proper level." In the analog domain, 0VU was "the proper level," and most analog equipment peaked (distorted) at +22 dBU, which implies -18 dB from peak as "the proper level." This is literally where VU meters were calibrated (and still are). Since 0 dBFS is the digital equivalent of the analog peak, many people, including myself, still adhere to "-18 dB" from top, and that means -18dBFS in digital. But this is an RMS level, not a peak level. Peak is a spike, RMS is the average. That's what a VU meter measures: the average.

Some people record with the average at -16 dBFS or even -14dBFS. Is that "wrong"? It just means that when it comes to mix time, all your faders will be slightly lower in their range compared to (my) scenario where my nominal average was -18dBFS. I am uncomfortable going as hot as -14 dBFS, but that is because I have OCD with gain staging and "0VU is the law" is burnt into my brain. But again, as mentioned before, 24bit recording has so much dynamic range (144 dB theoretical) that these small ~4 dB differences do not amount to anything anyone can hear. They literally do not.

The "-12 dB" level setting is also a peak meter, and for example, if you were recording distorted electric guitars with peaks hitting -12, your RMS value is likely more like -16 dBFS. Totally fine.