Tascam Model 12 Midrange noise problem

[Glen Dietz]

Hello,
Just bought a brand new MODEL 12. Turned it on and found a problem that hopefully is unique to me and not to all Model 12s.

Does anyone have an issue with the MID knob controls creating a noise? Basically, if I adjust the MID GAIN higher or lower than 0 (zero), a noise kicks in... you need to have your MAIN or SUB outs jacked up fairly loud to hear it, but it's noticeable enough even at normal gain levels. No instruments need to be plugged in either.

The noise changes by adjusting the MID FREQUENCY knob after the GAIN is set higher or lower than in the middle. It's pretty bad the lower you go with the FREQUENCY knob. The sound completely disappears once I set my MID GAIN back to zero, which makes me think something is wrong with my mixer, or this is normal. I don't know... I updated the firmware. That's about all I can think to do.

I can set it to 400hz, for example, then sweep the gain high or low and I get what sounds like a white noise with a low cutoff filter. It's constant at whatever gain I set. It sucks and could possibly make the midrange eq unusable, since I'm typically cutting the lower mid frequencies.

 

[JSchmo_Bass]

The mid EQ on all channels or just one channel in particular?

Or are you referring to the Main output EQ (upper right section)?

 

[Glen Dietz]

The EQ on all channels, not the Master EQ, which is flat/off.
The noise is present on all channels. If I hit the 100hz cut button, the noise is mostly canceled, so the noise in the lower frequencies. I think the maybe because the eq is digital and it may be throwing an algorithmic type of effect over the adjustable mid frequency, whereas the hi and low are more like analog? I don’t know.

 

[-mjk-]

Is this happening with the unit not connected to anything except monitors or headphones?

 

[JSchmo_Bass]

I just put mine through the paces.

-Nothing connected to the inputs.
-Channel pre amp gains at noon (i’ve never needed more that a hair over and usually set to 0/11:00 for a loud band using mostly SM57’s)
-Channel faders 0db
-Master fader at 0db
-Headphones volume at 75% / 3/4 up

If I were to “hit play” on a set of receded tracks or even line level Bluetooth inputs at this point the playback is waaay too loud and the master meter is flirting with yellow and red. In practice my working levels are lose and my headphones level is usually set at 30-50% depending on which set of cans. So the above settings are seriously “cranked” in order to hear the noise.

With channels on MTR- the unit is pretty silent- a very very low level of buzz if i crank master fader up past 0 to its max range. I am guessing this is 60hz noise or RF from nearby stuff.

Setting a channel to LIVE brings in an audible level of white noise, present equally each channel and that rises or falls in proportion to the either the pre amp gains OR the channel fader position. Channels 1-6 have a low roar and the two stereo channels have a higher pitched hiss. I assume this is the self noise level of each of the pre amps. More channels on =more white noise in the master bus. The levels can actually improve or worsen if you connect things to the channels. Overall never an issue in real use, but it does exist if you push it.

On my unit, Moving any channel EQ in either of the above modes does absolutely nothing other that change the EQ of the white noise. everything works as it should.

 

[Glen Dietz]

Thanks for running a test on your unit. Yeah, you do need to crank the volume loud to hear it. It’s present on all outputs, including headphones, including LIVE or MONITOR mode, with or without any instruments plugged in.
Basically, one expects static/white noise an any audio equipment when boosting volume. I just think it’s weird that an ADDITIONAL noise is added when adjusting the mid range knobs. It’s thicker than the typical static, and you can immediately cancel it by turning MID gain back to zero. This makes me think it’s an internal issue or design flaw. Obviously, the first thing i did was go through all ground loop diagnostics to no avail. This mid range noise could be a real issue outside of the studio in a live setting.
A work around is engaging the 100 hz cut button to filter the noise on channels where mid range adjustment is needed, however, on a bass track or kick drum, i need those lower frequencies, so it’s still problematic.

 

[JSchmo_Bass]

Yeah, shouldn’t happen. And doesn’t’ happen on my unit.

the Model 12 is really quiet (it’s quieter than the Model 16 in head to head comparison with same settings)

You should contact Tascam (or if you just bought it, contact seller return and ask them to send you a replacement).

 

[Glen Dietz]

Thanks for checking yours...
I contacted tech support at Sweetwater. They have not encountered this issue with any other customers as of yet, so they’re sending a replacement today. I’ll update this thread when I test the new one.

 

[JSchmo_Bass]

Sweetwater is good with at that sort of thing.

definitely let us know how it comes out.

I did pick up slight noise issues in both of my units as follows:

M12 - when rapidly adjusting headphone volume, a slight digital glitch sound in the headphones.

M16 - when loading/saving/renaming a file, a slight digital chirp sound (like an old modem) in headphones while the “processing” icon is on screen

Neither of these are loud and neither interfere with main operation in any way. Not really an issues in my book. I was chalking it up to the design - headphone amp circuit being close to the MTR circuit.

 

[Glen Dietz]

Got the new mixer. Same problem. To avoid any confusion or misinterpretation, all I need to do to experience this noise is:

1. Leave everything unplugged from unit (mainly for safety on your headphones or speakers incase you accidentally hit a note on something)
2. Pick ANY channel and leave PRE all the way down. It will have no effect for this issue.
3. Pick ANY channel and push fader all the way up.
4. Push MASTER fader all the way up.
5. Set MID to 100Hz to 500Hz... anywhere in that region.
6. Adjust MID gain up or down from zero.

You should hear a pop once the MID gain is engaged ( up or down from zero ).
You should hear a low frequency noise that's thicker than the white noise you're already hearing.

My guess is this has to do with the digital nature of the board... The EQ is like an effect more than it is like a filter, if that makes sense, so there's a digital-related artifact in the audio for this particular parameter. I'm not an expert, this is just guessing based on years of using digital FX and so on. This is also why digital is sucky.

Now, either I'm extremely unlucky to receive 2 Model 12s with the same noise, or there's some strange electro voodoo in my studio, or you guys work for Tascam and that's why you can't hear it

You can argue that these gains are unrealistic, or that one would never need to push these levels, but I can hear that damn noise every so subtly at normal volumes.

 

[JSchmo_Bass]

I am going to try exactly that later tonight

mean tome... One more quick question have you updated the firmware of these units to the latest version which is dated December 15, 2020?

 

[Glen Dietz]

Yeah, firmware is fully up to date. V1.21

 

[JSchmo_Bass]

Dude! I set mine exactly as you said, and YES I get the noise. Exactly as you describe.

So in fairness those are very extreme settings ... I don’t know if I would have ever hit on that combo.

I rarely have faders past unity gain. But annoying none the less.

Next step - let’s see if that noise “prints to tape” while mixing down and making a live adjustment to the mix. I will try an experiment tomorrow.

arguably if it is only in the headphone mix, and at such extreme levels, it matters not.

 

[Morgelec]

Yes, I hear it, especially when I adjust the gain up from zero. I'm not noticing at normal levels but my ears are getting old. I will listen a little closer to hear if I can pick it up at normal levels.

 

[Glen Dietz]

Thanks for running that diagnostic, guys. At least I can feel better than I'm not going crazy!

 

[-mjk-]

OK, I have been following this thread and I think I see what's happening here. This it not an uncommon phenomenon actually. I've done this myself with some gear just to see what would happen. In order to create the situation you described, the following conditions must exist:

1. Leave everything unplugged from unit (mainly for safety on your headphones or speakers incase you accidentally hit a note on something)
2. Pick ANY channel and leave PRE all the way down. It will have no effect for this issue.
3. Pick ANY channel and push fader all the way up.
4. Push MASTER fader all the way up.
5. Set MID to 100Hz to 500Hz... anywhere in that region.
6. Adjust MID gain up or down from zero.

Please note:

These are impossible conditions for creating music on the Model 12.

The Model 12 was not designed to do anything useful under theses conditions.

First of all, putting the Master fader and the channel fader all the way up would never be a real-world condition unless something was seriously wrong with your input levels. And if your input levels were normal, having both those faders maxed would totally destroy the audio with distortion and probably blow your monitor speakers in the process.

Audio devices are designed to be loaded, that is they are designed to have things connected to them that present a load on them at specific impedances. We already know that improper impedance matching can cause serious audio degradation, but who knows what might happen with a device that is completely disconnected to the outside world and maxed out. And, truthfully, who cares what it does with nothing plugged into it? You can't use it that way. When measuring the noise floor of a device, normally the device under test would have the inputs shorted. That prevents bad things from happening (like oscillation) that would affect the noise floor measurement.

You can take almost any device that you can think of and find some combination of extreme settings that create a situation that would appear to indicate a malfunction, but it's simply a matter of pushing the device into a condition that is unintended by design. The combination of settings that are required to achieve this abnormal condition would never be applied in a normal setting.

Plug all your stuff into it. Play some notes on a keyboard or some other instrument. Adjust the levels for normal and adjust the monitor speaker level to a normal level. Now, see if it makes any strange noise. Seriously, who cares what it sounds like dunked under water, run over by a car, with a cup of coffee spilled on it, or nothing plugged into it with everything maxed out because you cannot possibly expect the unit to function as a musical device when none of those above situations have anything to do with it's primary function: recording music.

With everything turned up you are hearing the unit's shot noise. So, certainly adding the EQ circuit into the signal path is going to affect that noise too.

I feel bad reading this thread because apparently this "malfunction" has prevented you from trying to record with it. The fact that @JSchmo_Bass can also reproduce the noisy condition with "very extreme settings" (his words) and yet has never experienced problems (and didn't notice it until duplicating those extreme settings) when recording music is because using the Model 12 with normal settings works well.

So, I say get on with cutting tracks! That's what we're here for!

 

[Glen Dietz]

Fair enough. Try this... with or without anything plugged in.

You don't need to set your gains all the way up on the channel and master faders... Just set to zero (I wanted you to hear it first so there was no mistake). You will find the noise is still audible at zero. That being said, those are the EXACT conditions in which this mixer is meant to be used, which makes that noise hard to swallow based on 3 points:

1. Tascam's reputation
2. The price tag
3. A mixer that's less than half the price doesn't have this noise problem

And for the record, I didn't force these conditions through ill-conceived methods of use. I heard a noise while setting up the first day just running synths thru the mixer, thought it was a ground loop at first, and then I went through all kinds of tests to figure out where the sound was coming from, which brought me to the conclusion that is now documented and confirmed by other Model 12 owners.

There's no justification for the noise just because someone else didn't notice it until it was pointed out to them. A seasoned mechanic would know when something seems off with the transmission of an automobile, so just because someone else might not notice, is the car still okay to drive indefinitely? * the answer is no

Now maybe I'm totally mistaken about this forum... maybe it's just for guys who are on the Tascam payroll or bandwagon or whatever. If anything, this type of thread is exactly what these forums are good for. So the next guy who hears this noise will have a shot at searching the internet for a solution rather than go through the tedious and frustrating ends I went through to figure it out.

Don't feel bad I didn't record with the Model 12 because I thought it had a problem. Feel bad for Sweetwater who's dealing with a second return.

 

[JSchmo_Bass]

I confirm the noise will be recorded if you record a blank track with no signal while tweaking the EQ.

however I have yet to perceive that noise when a signal is flowing down the channel strip, either from a Live source or from a digital source (PC, MTR).

Now may be simply my ears (I am 52). But surely it’s also a function of how I tend to be setting levels; as MJK says, under actual use conditions are we really pushing the faders nearly that high? (I certainly am not, I unless I inadvertently record something very low level). I am usually working between -15 and -5 for a given channel, occasionally up to 0.

Between that, and the relative rarity of making a mid-play adjust to the EQ for a “good” recording take, to me this is pretty much non issue.

I find the Model 12 noise floor to be very quiet overall, with good signal/noise characteristics. You can really get dynamics to pop on this thing if you get the tracking set up right (I respect the mid line on the meter!)

I may experiment tomorrow with some very low level tracks to see if the noise occurs when the channel is loaded ith signal. Easy to avoid it even if it does, but indeed worth knowing it’s there.

 

[JSchmo_Bass]

So I add 2 further comments

- I only hear the issue on channels 4 and 9/10

- i tried putting plugging mic in to channel 4 and recording very faint sounds in the top
while twirling the knobs.

No way is this an issue in practice : the levels that this noise occurs are WAY boosted vs any reasonable levels of recording ... I cannot hear it at all over the faint room ambient noise captured by a condenser mic plus the mic’s self noise.

of course the EQ is shifting as one twirls the knobs.... and that does make a big impact on sound including the room. To me it’s not a common “move” to change EQ in mid recording on purpose... only during preliminary mixes for the most part.

So in conclusion, my personal opinion is this a small thing, something they at Tascam might tidy up at next iteration, but otherwise a NON issue for users.

 

[Arjan P]

So in conclusion, my personal opinion is this a small thing, something they at Tascam might tidy up at next iteration, but otherwise a NON issue for users.

It might not be an issue for you, but apparently it bothers the OP and he hears it also at lower gain levels - and the issue may not be the same on every unit..