Tascam 48 Issues

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Mischmaschine9000

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Hi, i recently got a tascam 48. Everything is working fine, but there are two things im not wuite sure about:
1. the noise level in repro on the xlr outs is approx -45db which seems a bit high to me..could it just be a tape calibration issue?
2. I have very audible wow and flutter going on. The left tape tension arm is bobbing up and down while running the tape.. could this be the cause?
Thanks!!
 
1. Lots of questions. I don’t know if it is a tape calibration issue because you’ve provided very little detail. Please answer all of the questions. Is it also noisy on the RCA outs, but maybe, like, -57dB? Is the noise the same whether the monitor source is set to INPUT, SYNC or REPRO? Is the noise present the same across all outputs 1-8? Is the noise present regardless of the transport mode (like can you hear the noise when the tape is moving and when the tape is stopped)?

2. I have no way to know if #1 is related to #2 without more detail, and may not even with more detail. What tape are you using?
 
Are you using new tape? Also, the XLR in/outs on this machine have no bearing on the signal that get recorded on the tape. They are an added feature for easy compatibility with equipment operating @ +4. In short, it's a built-in bump box.
 
1. Lots of questions. I don’t know if it is a tape calibration issue because you’ve provided very little detail. Please answer all of the questions. Is it also noisy on the RCA outs, but maybe, like, -57dB? Is the noise the same whether the monitor source is set to INPUT, SYNC or REPRO? Is the noise present the same across all outputs 1-8? Is the noise present regardless of the transport mode (like can you hear the noise when the tape is moving and when the tape is stopped)?

2. I have no way to know if #1 is related to #2 without more detail, and may not even with more detail. What tape are you using?
Hi,
thanks for answering - i try to provide the answers as clear as possible:
1. Noise while running tape in repro and sync mode is - between -57 to -47 across the channels (XLR out)
2. Noise on input mode while running and not running is around -72 to -80 across the channels (XLR out)
3. The machine does not generate noise on sync and repro when its not running tape. -72 to -80 across the channels (XLR out)
4. With RCA outs its around -60 to -65 across the tracks with tape running in repro and sync. With no tape running its around -80 to -90
5. Im using a fresh reel of RTM SM911
6. The machine got a service and was supposedly calibrated for the 911. Frequency-wise it measures reasonably flat with a little bit of headbump.
7. Today while recording through the whole reel and listening on repro there was a sudden high frequency loss halfway through the tape. After a few seconds everything was normal again. On a second recording session i noticed it around the same time (halfway through the tape. I thought maybe that could be interesting to know..
 
Can you describe your entire signal chain from source to monitor? What is your source - music or a tone or tones?
 
Can you describe your entire signal chain from source to monitor? What is your source - music or a tone or tones?
I tried with music and tones.
The chain is orion32+ 8channels output to tascam 48 input and the the tascam outputs back to the orion 32+ inputs. The cables and interface work flawless.
 
Are you using any noise reduction? If not then your noise levels are within spec.
 
It’s still the same level of noise relative to the signal level. The RCA jacks are -10dBv nominal, the XLR jacks are +4dBu level standard; about 12dB difference. The noise is quieter…so is your signal.
 
It’s still the same level of noise relative to the signal level. The RCA jacks are -10dBv nominal, the XLR jacks are +4dBu level standard; about 12dB difference. The noise is quieter…so is your signal
Ok it seems i have to live with the noise or get a noise reduction system.
 
Yes, that is one option…it is part of the nature of recording using analog tape, and the 1/2” 8-track format is not free from this nature…more susceptible than some other formats depending on the machine.

Noise is noise. On a tape machine it is the product of the base noise floor of the power supply and electronics in the signal path, as well as the tape noise itself which is largely a product of the mechanical activity of the tape gliding across the heads. In a “vintage” machine like the 48, if it’s not been addressed, often times a recap of the power supply might lower the noise stemming from the electronics a measurable amount (but not substantially compared to the innate tape noise). Otherwise the noise is the noise. But there are a couple ways to address it; to improve dynamic range.

Dynamic range is the amount of sound level difference between the noise floor, and at the other end your signal. If the dynamic range is relatively small, then the noise can be more frequently heard amidst your program signal. We perceive this as the noise being “louder.” The other way to think of it is the dynamic range is too small. So how do we increase the dynamic range? Either make your program signal louder on tape (which can also be perceived as your noise being quieter), or employ processing that reduces the noise (noise reduction)…or do some of both, though there are limits to this because making your signal too hot on tape can mess with some noise reduction processing causing unwanted artifacts.

Making the signal on tape “louder” is easy…just record hotter. And if recording hotter is undesirably saturating (distorting) your tape, then get tape that can handle hotter signals before saturating than your SM911, like SM900 for instance. But understand that will require re-biasing and ideally recalibrating the machine. And also be aware if getting tape that can handle hotter signal before saturating, and printing “louder”, is still not bringing satisfactory results as far as improvements in dynamic range, and you reach a point you are driving things so hard you are clipping the signal electronics, then your only solution is either tone down how hot you are printing to tape and bring noise reduction processing into the picture, or…get a tape machine with more robust signal electronics that have higher headroom…can drive signal to higher levels than the 48 before clipping.

Welcome to tape.

Let me know what questions you have.
 
Yes, that is one option…it is part of the nature of recording using analog tape, and the 1/2” 8-track format is not free from this nature…more susceptible than some other formats depending on the machine.

Noise is noise. On a tape machine it is the product of the base noise floor of the power supply and electronics in the signal path, as well as the tape noise itself which is largely a product of the mechanical activity of the tape gliding across the heads. In a “vintage” machine like the 48, if it’s not been addressed, often times a recap of the power supply might lower the noise stemming from the electronics a measurable amount (but not substantially compared to the innate tape noise). Otherwise the noise is the noise. But there are a couple ways to address it; to improve dynamic range.

Dynamic range is the amount of sound level difference between the noise floor, and at the other end your signal. If the dynamic range is relatively small, then the noise can be more frequently heard amidst your program signal. We perceive this as the noise being “louder.” The other way to think of it is the dynamic range is too small. So how do we increase the dynamic range? Either make your program signal louder on tape (which can also be perceived as your noise being quieter), or employ processing that reduces the noise (noise reduction)…or do some of both, though there are limits to this because making your signal too hot on tape can mess with some noise reduction processing causing unwanted artifacts.

Making the signal on tape “louder” is easy…just record hotter. And if recording hotter is undesirably saturating (distorting) your tape, then get tape that can handle hotter signals before saturating than your SM911, like SM900 for instance. But understand that will require re-biasing and ideally recalibrating the machine. And also be aware if getting tape that can handle hotter signal before saturating, and printing “louder”, is still not bringing satisfactory results as far as improvements in dynamic range, and you reach a point you are driving things so hard you are clipping the signal electronics, then your only solution is either tone down how hot you are printing to tape and bring noise reduction processing into the picture, or…get a tape machine with more robust signal electronics that have higher headroom…can drive signal to higher levels than the 48 before clipping.

Welcome to tape.

Let me know what questions you have.
Hey,
thanks so much, this was very helpful. Did a lot of recording and testing with the 48 the last days and the noise is not a problem with proper gainstaging.
The wow and flutter issue suddenly disappeared, which is a bit strange but good for now. The remaining issues now are high end and level loss for a few seconds on three channels. I can bring the machine back to the tech who serviced it for me, he will take a second look at it - will report back how it went.
 
Diminished high frequency and level performance on three tracks for a few seconds? You mean, like, you hit play and it takes a bit for those three tracks to perform properly?

Are the three tracks adjacent to each other (like 6, 7 & 8 vs something like 2, 5 & 7)

Does it do it when playing back a known good recording or and only happens on something you recorded in the 48, or does that not matter?
 
Diminished high frequency and level performance on three tracks for a few seconds? You mean, like, you hit play and it takes a bit for those three tracks to perform properly?

Are the three tracks adjacent to each other (like 6, 7 & 8 vs something like 2, 5 & 7)

Does it do it when playing back a known good recording or and only happens on something you recorded in the 48, or does that not matter?
Its on tracks 1-3 it happens randomly when i am monitoring in repro while recording. I send from my mac and record the repro signals back to the mac, so i have to check if the loss is there when i rewind and play back the same part.
 
So it happens when recording…playback only is fine? Like does it ever do it when you are playing back? And I don’t mean when you’re monitoring the repro head during record…the reason I’m asking this is if the issue occurs during record and also during reproduce, and it’s across three adjacent tracks, the first thing would look at is tape tension. If it only does it in record it’s something related to the signal electronics. These are my hunches. But clarifying in what modes the issue occurs is important. At least relative to my hunches.
 
So it happens when recording…playback only is fine? Like does it ever do it when you are playing back? And I don’t mean when you’re monitoring the repro head during record…the reason I’m asking this is if the issue occurs during record and also during reproduce, and it’s across three adjacent tracks, the first thing would look at is tape tension. If it only does it in record it’s something related to the signal electronics. These are my hunches. But clarifying in what modes the issue occurs is important. At least relative to my hunches.
Hey, i had the machine at the tech for a second time now, wow and flutter are fixed abd the calibration is fine. The sudden volume and high frequency loss are still there..according to the tech everything is working.. Its most apparent on channel 1,2 and sometimes lighter on the remaining channels but not as worse as on 1 and 2. when i record a signal and play it back its reproduced exactly as in the recording with the volume drops and everything. I do not have a prerecorded tape to check if it is in repro only, maybe i can find one in town. Also whats new is a fast mechanical rattling when rewinding tape for the first few seconds, there seem no loose parts, but only from the outside. The rattling is quieter when i am halfway through the tape and rewind.
 
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