Most of Tascam high end audio products claim they use Tascam HDDA input amplifier tecnique and 5532 amplifiers (except Dr701)).
I have not seen any diagrams but to me it is interpreted as Tascam input amplifiers has a discrete transistor input stage combined with 5532 opamps which together set input noise levels obtained.
That may explain why it did not change a lot to switch 5532 amplifiers with even less noisy amplifiers as discrete components are still a major part of noise levels.
Anyway I would personally not really care of the present noise as that is hardly the limit for most users compared to microphones used generally.
However i have seen in other forums that people struggle with camera/line out especially camera out which seems to have severe noise problems due to some design flaw with output amplifiers.
Most users referred with this problem has solved this S/N problem by neglecting camera out (which should have been an attenuated line signal) but using the line out signal and purchase a cable with builtin attenuator (25dB in this case).
Camera out was probably intended to be used with DLSR cameraes which have a microphone input with high sensitivity so lineout needs to be attenuated to fit this input signal level.
By using the line out with proper gain settingsfor this it seems to be working but using cameraout it seems to be a degraded lineout signal with lower S/N level that is not of decent quality. That is a pity :-(.
Does anyone in here have any experience on this problem with Tascam line out versus camera out settings and how it could be related to lineout gain settings eventually and why it is better to use an attenuator cable instead of internal gain setting? Again this could be a design flaw similar to camera out.
Well...
I made a few measurements with the DR70 line out, and guess what: I did not recognize the problem that a lot of other people have met when using the lineout signals and found too much hiss with camera out.
Are there any information that the latest version 1.13 should have removed this hiss problem or are we up against some basic operator problems here incl me?
Basic is that hiss should be measureable like any other signal.
Difference of line out and camera out is a level difference of 30db (camera out is line out -30db)
so i made a test of measuring noise at line and camera out and it shows a difference of 30dB as stated and no more or less noise at camera out.
a simple setting is that at monitor you may set lineout to -18dB and camera out to +12 dB and voila you get the same volume output at line/camera out. (measuring AC at output)
So how can this be explained.
Does this problem not exist other than people abusing level settings when connected to DSLR's and similar or am i missing something.
Why would people go out paying for expensive cabling (attenuators) to solve a problem that may not exist?
I just cannot see it, sorry.
This is one of the forums that claim this to be a problem and some reports here say that problem is present at least with ver 1.12:
http://www.dvxuser.com/V6/showthread.php?329630-Tascam-DR-70D-what-do-you-think/page19
I am still puzzled of this problem that some people claim Tascam makes noise out of LINE/CAM output, welll I cannot make it happen, sorry guys.
May be it is because i do not have a GH4 that is part of the problem, but i try to be objective and get some value facts.
Actually no one claims it to be noisy but claim that S/N is worse when CAM Output is used, but my claim is that it is NOT, problem must be elsewhere in the understanding of connecting a second MIC amp (GH4)
As S/N is the clue i do not care of signal levels but try to measure noise levels of Tascam.
my setup is:
Input CH1 is shunted by 150 ohm impedance simulating a low noise microphone at XLR.
GAIN is set at max HIGH PLUS (+63dB)
LINE Output is taken into some recorder, I have used Sony M10 but it could be any lownoise amplifier/recorder but it could also have been a quality AC Voltmeter but we are talking of very levels (uV).
Output at LINEOUT is Input amplifiers selfnoise (amplified 63dB) which is claimed to be better than -120dBu (<1uV)
The picture below is showing noise output at LINE OUTPUT at LINE GAIN settings of +10 dB/0 dB/-10dB/-20dB/-30dB
Same picture can be made for CAM output which is LineOutput -30dB.
These steps on recorded noise show exactly 10 dB attenuation for all steps so no additional noise is added at different attenuator settings nor for CAM Output.
Claim was that noise is increasing on LINE/CAM Output when attenuation is set lower and therefore attenuation cable would make a difference.
Well it is not TASCAM that is producing this noise as you may see at picture which is total noise coming out of LINE OUT with input shorted and displayed with Audition from noise file recorded with M10.
I am not able to conclude what makes GH4 a problem with Tascam, which seems to be a fact as well, but it is not explained by a noisy output of TASCAM unit
Conclusion is that you will have the same noise and S/N whether you use Tascam attenuation on LINE OUT or CAM (-30dB) and it would not normally need any attenuation cable
Maybe others could dig into this problem with GH4 and have a conclusion that is eatable, but I am convinced that it is not caused by TASCAM DR70.
TASCAM DR70 is a fine recorder but have to be used with care as any recorder.
PERIOD.
I hope you forgive me being stubbern on this :-)
a little "googl'ing" gave this, which might explain a lot:
http://suggestionofmotion.com/blog/panasonic-gh4-audio-buzz/