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SD Mixpre-6 Time Code Input


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Hi-

 

(For a friend)

 

He has never used time code before because he normally records music without any video component.  But he has been asked to record some pieces with three cameras shooting for video distribution and must now concern himself with TC.  He ask me, and I will confess that although I am super-familiar with time code, I have no idea how he can feed time code into his Mixpre-6 (am I right in thinking that there is no TC generator in this box?).  I see the HDMI TC input in the manual but how can he get that input from what I would consider a "standard" time code generator like a Denecke TC SB box?  Can speak to what cameras will be used, but I could find out if that was necessary.

 

Thanks for any quick thoughts.

 

D.

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I believe you input the timecode through the Aux/Mic In 3.5mm input. The MixPre 6i doesn't have a generator but I think the Mixpre-6ii does. So, you would need to leave a timecode box attached to the first generation. This is how I recall it being but I could be wrong.

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Thanks so much.  Yes, I think this is a v.1 Mixpre-6.  Lemo pin #1 to mini-TRS sleeve, Lemo pin #5 to miniTRS tip.  Now to find out who's supplying  master sync and what the cameras' T/C inputs are.

 

And Joshua.  Why is that?  Four mics in and an outboard T/C generator.  I think it will work just fine.

 

D.

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No need to rent a bigger mixer. The mixpre6 is a beutiful machine.

 

You need to set the mixpre TC to EXT on Aux1 and use a TC cable that outputs on a 3.5mm cable for the aux input, simple as that. It is intelligent enough to autodetect the fps from the generator. It also accepts varying levels of signal, but think line is generally preferred if there is an option for volume on the TC box.

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Oh, dude.  This is the most respected classical music recordist in this city.  He has his closet full of top-rated gear.  He is choosing the Mixpre-6 for a specific reason; small and time-code capable bit-bucket.  I suspect that he will use Millennia or Grace pres for the front end.  He need a machine that will record four inputs and print time-code.  Seems like there is no need to use any other device.

 

FFIW, he almost never does jobs that have a camera involved.  So while my many years in the motion picture business imparted the necessary time-code schooling, he has almost no reason to concern himself with it up to now.  He just wants to know how to get TC on his tracks because the client requested it.  I'm helping him figure it out.

 

D.

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Thanks Chris.  Good thought and I'll ask.  I suspect that if the program looks like others, and with three cameras, it would be easy and done without thought to cut back to the wide shot to regain "lip" ("bow"?) sync.  I also think that this won't be done in any super hi-budg manor and that cameras will be lo-end pro or prosumer. So the whole project may be a typical sloppy mess.  I am just trying to help my friend do what is in his control to make it better.

 

D.

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Puts on pedants hat.......

 

As I understand it - the v1 Mix Pre does not 'clock itsself to the field rate of the incoming TC' at all. Remember that we are talking about a digital recorder, that makes a .bwav file, and that a .bwav file has a TC sync value in the file header.

 

As I think we are all aware... the TC sync value is calculated as the amount of 'samples after midnight' (00:00:00:00) counted at whatever your sample rate is (probably 44,1k or 48k in this case). This value then gets calculated back to a TC value (using the TC rate of the shoot) when the file is played back, or used in post production.

 

So - in the case of a v1 MixPre6, it will look at the incoming TC, and at the moment that the new record file starts, it will take the TC number, calculate what that value is in frames since midnight, and record that value in the file header. At no point in all of the above is the recorder clocking itsself to the incoming TC.

 

The recorder is clocked to an internal clock, from which it derives its own 44.1 or 48k sampling rate. In post production the DAW or video edit software will be deriving its own clock from somewhere. It will, say, 48k of audio samples into a similar 48k of timeline space.

 

So - in practice.... the clock on the mix pre will easily be 'accurate enough' that over even a long take (2hrs or more) any 'drift' will be entirely irrelevant. 

 

In truth the cameras are not locked to some sort of clock then they are more likely to drift with respect to each other than with respect to the sound. So long as the TC shows on the display then you are in business. I seem to remember that you might have to tell the mix pre what the TC rate is, simply so that it puts that value in the file header, and things work out best then in post.

 

You can send analogue TC into the Aux5/6 3.5mm jack socket on the mix pre. You will have to tell it that the aux in is going to be the source of the TC and it will look for it and show it on the display.

 

Agree that there is absolutely no need whatsoever to have a better or posher or more grand machine. 

 

Hope that this helps.

 

Simon B

 

 

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On 6/18/2020 at 8:56 PM, Philip Perkins said:

And clocks itself to the field rate of the incoming TC, right?

 

No they don't "clock" to timecode.

They clock internally, the timecode is only a position locator.

 

Ive tested the Mixpre 6, and they drift.

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1 hour ago, TVPostSound said:

Ive tested the Mixpre 6, and they drift.

 

Just to be clear, since there is no T/C generator in the MixPre6 v.1, whatever T/C generator that was plugged into the MixPre6 drifted?  Can I assume that any top-shelf generator would present accurate code to the file headers on the recorder?   Perhaps the cameras' internal (read "crappy") generators drifted?

 

Thanks.

 

D.

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1 hour ago, tourtelot said:

 

Just to be clear, since there is no T/C generator in the MixPre6 v.1, whatever T/C generator that was plugged into the MixPre6 drifted?  Can I assume that any top-shelf generator would present accurate code to the file headers on the recorder?   Perhaps the cameras' internal (read "crappy") generators drifted?

 

Thanks.

 

D.

 

 

Time code does not equate to speed, its only a positioning marker.

Reference (black) (word clock) keeps speed.

 

Time code locks to a position, then freewheels unless a common reference clock addresses both units to be synched.

HDMI TC in on the Mixpre 3 carries both clock and timecode, from the camera.

Think Pilot tone before we had time code.

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But he is not planning on taking T/C from the cameras (and who know what those cameras even are and he doesn't care) but from a T/C generator, a Denecke GR1.

 

The cameras will need to take care of themselves via a jammed SB1.

 

D.

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Yeah in a real world scenario it should be fine. Never had a single issue using tentacle and MP6.

 

Apart from once but that was the issue of a RED "accepting" a different TC than it was actually shooting. So in  this single case I would not blame the MP6/F8 it was recorded on either. And it was easy enough to batch change the tc header from 24 to 23.97 in waveagent once I figured out where the problem was.

 

 

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