Tascam Model 12 Midrange noise problem

[Remi Lacroix]

https://www.tascamforums.com/members/mjk.8288/
Hi MJK, You put a like on my post, but do you have any clue upon what's going on with my problem ? ... I mean, what do you think it is ? ... Dust ! (Everything is very clean). bad wires, (I have all new wires) ... I had a problem when trying to plug into, input G, track 7 ... I admit, I forced it in a little ... But still, everything was A one, ... Now I'm getting really bad distortion or white noise ( sorry if I'm loosing my english ) Now with nothing plugged in I get very loud distortion noise, witch I never had before ( I did some test when I bought my Tascam Dp 24) Everything was WOW ! ... No white noise or hiss or any distortion at all. My question is : What happened ? What do you think it may be ? ... Please, ( sorry if I am not chatting in the right room, I search all I could through the forum and this one was the closest I could find ... I am new here and kind of feel like an imposter, all you guys are pros compare to me ) ... I can't believe I had this Tascam for 10 years now and only starting to learn about it. Well I guess what being retired means. Try new stuff, explore new ways to find another passion into life... Well I said enough now, only one more word ... Thank you

 

[Remi Lacroix]

https://www.tascamforums.com/members/shredd.9904/
Thanks shredd, the problem is that everything was perfectly set, then I took a little coffee brake and when I got back I could here that distortion white noise. What happened meanwhile ? ... Thanks for your time I appreciate even if it does not resolve my problem ... So ... in return if I find out about it, I will surely share what the problem was ... I really do not feel like taking it all apart to find out ... I know how much patience it takes with all them mini small parts, I'm not in good physical shape ( I shake quite a bit ) That comes with age and lots of pain ... Better laugh at it ... Thank you

 

[shredd]

Hm. Sorry to hear that - it's very strange that everything is set as you wish, sounds good, THEN later has horrible noise when you haven't done anything. The only thing that makes sense is that something is going wrong as it sits - overheats/overloads, something like that.

I've read here n there that sometimes this is a power-supply issue (gets noisy as it gets hot, overloaded, whatever?). This is something that the Smart-ysh Doods here that have a clue about electronics tech could address...I'm clueless. I spend the first 10 minutes of every session trying to remember which way the pointy end of the guitar goes. Brain Death is SO sad, don't you think?!?

Good luck!!

 

[Mark Richards]

DP-24...white noise...track 7...Got new cables, still the same...factory reset track and unplugged everything...still ear that noise...every track...same white noise...turned the trim/ gain knob all the way up, leave all tracks down...lift up the master level...white noise...high enough so I can see it...on the output lights...still hear white noise when the trim/gain knob is at the lowest...Everything is OFF, EQ, Dynamics, Effets everything is set on !Factory reset

Shredd's gain staging idea is a possibility. But as the noise presents with all controls set to minimum or off, and still is visible on the Stereo Master Bus meters at unity gain, there's something more basic going on if you're absolutely certain your factory reset has turned everything back to the original, out of the box, condition.

So shredd's comment on possibly being power supply related may be something worth considering (for example, is the unit connected directly to the mains; what else is on the power circuit; is your DP-24 connected via USB to your computer, etc.)

Also look through all the "2488, DP24/32/SD" forum sticky thread indexes; and if still no joy, try a general search of that forum for white noise threads or power supply threads.

If still no joy after searching that forum, I'm guessing the only real option for you is systematic, methodical testing. There are many variables involved, requiring a lot more precise information using exact TASCAM descriptive terminology, before we might be able to offer an informed, educated guess.

Yours is a specific DP-24 digital portastudio question. In the future, when you have a question, posting in the "2488 and DP-24/32/SD" forum rather than posting in this "Model 12/16/24" forum could also help another portastudio owner who may experience the same thing.

 

[Remi Lacroix]

Thanks Shredd and Mark Richards... I did some search into the forum hopping posting at the wright place (thanks) ... I may have a ground problem, I live in a old house, and yess many things plugged into only one outlet. Thanks again. I think I found the wright place to post so I will copy my problem and post it into the 2488 / dp24 /dp32

 

[-mjk-]

@Remi Lacroix said:

Hi MJK, You put a like on my post, but do you have any clue upon what's going on with my problem ? ... I mean, what do you think it is ? ..

I am not certain. The others have given you some excellent things to check. In such cases I normally disconnect all outboard devices except the monitors and I try to establish what the nominal noise floor is for the unit itself. You may have a dirty preamp or track for some reason. If the unit is noisy on it's own at high gain you can try to raise the output gain of the devices that you put into the DP-24 so you don't have to add the gain in the DP. Honestly though there are so many variables that without methodical testing it is very hard to say what the exact problem may be. Do you have the Tascam test song for the DP-24? That is a good place to start with testing.

 

[Remi Lacroix]

Hi again, *thanks everyone* yes there is so many variables to check into. I had some recordings done just before the problem appeared, the sound is good, just has the demo song too is good. I did a little more test, I think the problem is within the inputs, or the pre-amp. Has soon as I raise the inputs trim gain the noise gets in and that is without anything plugged into it. (I do only a little work at the time 'cause I have lots of pains in my body and that affects my patience, better to laugh at it)
I'm an (old school) electrotechnician, it looks like a bad filter (capacitor) into the pre-amp. or a bad ground, I really don't feel like taking it apart to fix it. Has I know that now days there ain't much we can do to fix things beside replacing a module or so, and there is no more electrotechnician around (all retired) and I don't have any equipment to test things out.
One step at a time, I always figure out some ways to fix things, but this time it is a real challenge. The most frustrating thing is ... I was into a creative mood ... (It maybe hard to follow me on this issue, I posted at the wrong place, and did a copy/past into the 2488 / DP 24/32 forum) sorry.

 

[Tommayallday]

@remi did you happen to solve this issue? I am currently experiencing the same thing, except I sent the unit in to be serviced under warranty. They are telling me they can’t hear the hiss and sent a video, but they sent a video with all of the faders of the tracks and the master fader set way down low below unity.

 

[Mark Richards]

Remi hasn't returned since May 2023.

Remi's issue was with a DP-24 portastudio but got mixed in with this Model 12 thread (itself misposted in the wrong forum by the OP, Glen Dietz, MIA since March 2021). Glen's issue was mid-range adjustment noise that TASCAM corrected with a firmware update.

The DP-24/32/SD portastudio has been a very stable platform for over 12 years, so the problem Remi reported with his DP-24 Portastudio was likely a one-off (only 1 Input & virtually instantaneous).

A search on Remi's name didn't turn up a posted solution. It's likely, being an electronics technician, he either fixed whatever the problem was (he thought a bad cap or ground); or as he indicated in his last post (#47), decided not to investigate further and moved on.

 

[MistahKurt]

Just bought my model 12 this month and am also noticing a pretty substantial noise floor on live mode with no inputs plugged in, all preamps set to 0, and any amount of fader gain (below unity). Each channel with faders above 0 adds to the noise level. Firmware is on 1.42. Exists on both headphone and main outs, goes completely away when all channels are muted or faders go all the way down. I haven't tested in a different area of the house or on direct/PC mode yet as it's in a little jam setup, but will do very soon. Unsure how to measure the noise floor until I can record it but it's really bad. Feels noisier than my old Behringer ADA8200, but I haven't compared them head to head

Had anyone had any luck contacting tascam? Wondering what I can do here.

 

[Tommayallday]

mistahkurt,

I had the same problem. Floor was so loud that I couldn’t record dialogue. Paid something like 75 bucks to ship it out to them. They sent me some low quality cell phone videos of them “testing” it that were quite frankly bizarre. Went back and forth over and over arguing and they admitted that they could hear it but that it wasn’t enough to replace, and that “some varying noise floor in different units was expected and acceptable”. I sent so many different audio examples. They continued to just sent cell phone videos claiming it was fine. They shipped it back without being fixed or replaced. To be honest it was a nightmare.

 

[MistahKurt]

I read your previous post earlier and was thinking about how awful it was lol. Luckily I have a repair center 10 minutes from me, so I should be able to work it out a little better hopefully. Tommay, did Tascam provide a way to measure the SNR effectively?

 

[Tommayallday]

Oh that’s great that you are so close! Hopefully you can work it out with them in person. No, they did not provide a way to measure the SNR effectively. IIRC it is a subcontractor that did the testing? But yeah they sent a video with the faders down and argued with me over the noise floor, and I sent my own video and recordings and the kid that was the middle man was basically like “sorry we’re not doing anything”. I would imagine they wouldn’t be able to pull some shit like that if you are standing there watching them haha.

 

[MistahKurt]

New development, I can cut the noise with the onboard high pass filter. So it's definitely a problem with either the preamps, the first stage of ADC, or the power circuit. I guess I shouldn't be doing anything high frequency if I want to maintain my sanity lol

Yeah that experience really sounds terrible. I wonder how they get paid and why they wouldn't want to try and help I think I could prob charm them or pressure them into wanting to help me in person at the very least

 

[MistahKurt]

Okay I have one last thing to say. And for my use cases it works well enough for me (I have a separate transparent interface if I need it)

I took a look at the block diagram and noticed we have inserts on channel 1-2. When I used them, the noise was still present. I was assuming this whole time that the preamps were the issue, but it's actually the ADCs.

So the solution/patch is really just gain staging (Putting the most amount of gain up front [clarification edit: because this is the last and only clean amplification stage from this point on in the signal chain] ). Unsure how much of this is the "my first mixer" experience, but if my posts are just realizations of a noob, I'm a little embarrassed lol. I will say that I think the ADCs (at least on my unit) are pretty exceptionally bad or have bad integration. I don't think that they would make a compression/eq stage that you're not meant to use.

Here is my setup now:

1. Crank the pres to the max, have the signal go in as hot as possible. (Edit: without clipping)
2. Avoid boosting with EQ and just avoid the compression knob altogether.
3. Use channel faders as normal. Bring your typical loud sound to unity so you can have a lot of room to dial in your channel volume
4. Keep your main fader really really low, adjusting to your speakers/headphones as needed (like -25db for my setup)

 

[Mark Richards]

Sorry, @MistahKurt, but that's bad practice and bad advice.

Gain staging is not "Putting the most amount of gain up front". Gain staging is about balancing throughput to capture and optimize the nature, characteristics, volume, and clarity of the recorded signal, to include balancing the audio signal in the monitoring system (headphones and speakers).

When gain staging is executed properly, the recorded and monitored signal will be substantially above the already very low, virtually silent, noise floor of the mixer (a 103dB Signal to Noise ratio and an Equivilent Input Noise of -128 dB).

A good place to start learning about gain staging is the link in my signature to "Information on Impedence Matching, Gain Staging, Signal Routing [et.al.]". Pro sites like Sweetwater usually have in-depth articles on various audio engineering topics like gain staging.

Once you understand the basics, searching this site using terms like "gain staging", "unity gain", "low volume", "noise", "hiss", etc. will turn up authoritative and informative community discussions on proper ways to establish high quality signal throughput.

 

[MistahKurt]

@Mark Richards,

I think that link is to another post of yours about manuals, is it misplaced?

Yeah poorly worded on my part; enough gain to get over the noise and enough headroom for not getting distortion (by maxing the pres, I meant enough to not clip). I wish I could figure out exactly how much headroom I'm leaving before the ADC stage, but I can only see the LED it provides, so I've just been using my ears . The problem is that I'm definitely not experiencing the 103dB SNR rating. My unit has such a high noise floor from the ADC stage that the incoming signal has to be at the maximum non-clipped level to hop over that noise. Couldn't that still be called gain staging given the undesirable circumstances?

It's not optimal in general but in my case, I don't see how I'm supposed to make my experienced SNR better, considering that anything amplified after my ADCs also amplifies a ton of noise. EQ cuts can work, but then it's also cutting the content I'm putting through.

Thanks for your post though! It was not my intention to come off as argumentative and I hope I haven't!