Topic: SMPTE Time Code vs. Word Clock

[gratefulphish]

Requesting another education here.  My new R-4 Pro has SMPTE timecode in or out.  Stock V3s have wordclock outputs that look suspiciously similar to the timecode in/outs.  If I am running a matrix, using a V3 to run mics digitally in via AES/EBU to the R-4 Pro, and the board directly in to the other two channels, will using this connection (if in fact it can be used) assure me of matched tracks?

[live2496]

SMPTE is an analog signal that can be recorded onto audio tracks. It is used for synchronization of recorders, but it is not sample accurate.

Word clock is a digital pulse which has the same frequency as the sampling rate.

These two things are not compatible with each other.

Your four tracks will still be synchronized because they are being recorded concurrently. There might be a slight difference in A>D conversion times on the V3 and the R4.

[gratefulphish]

I was hoping to avoid that sync issue between the V3 and the R-4 Pro. Am I going to have sync issues even if I run mics directly into the R-4 on two channels and the board on the other two, just because of the amount of wires and electronics in between?

[wbrisette]

I was hoping to avoid that sync issue between the V3 and the R-4 Pro. Am I going to have sync issues even if I run mics directly into the R-4 on two channels and the board on the other two, just because of the amount of wires and electronics in between?

The issue you're going to run into is the board is a bit ahead of the PA, which makes perfect sense when you think about it. Vocals and instruments on stage have to go back to the board, then get turned around and go back on stage where the PA is. The amount of delay that has to be added varies. With the R-4, you maintain four separate tracks (right?), so you tweak the delay in a multi-channel DAW later. The only problem in doing this is providing a 2-channel feed out. The DEVA allows you to set a delay in the unit. This delay is used for the output, so I still have to tweak shows later in post. However, it really does work out better because you never know exactly how much delay to add and when you're in the field it is very tough to get it exactly right. At festivals depending on location and distance I sometimes don't have enough delay in the DEVA (I only have 40 ms), but usually this isn't a problem because most of the time I can't feed people from the sources I have, or if I am feeding them, it's minus stage mics and the board.

Wayne

[gratefulphish]

Thanks for the response.  Wish I had a Deva.  The R-4 does have four independant channels. Once I determine the delay to line things up, will I still expericence drift, or because the tracks are all on the same machine, should I be okay after that?

[wbrisette]

Thanks for the response.  Wish I had a Deva.  The R-4 does have four independant channels. Once I determine the delay to line things up, will I still expericence drift, or because the tracks are all on the same machine, should I be okay after that?

There won't be any drift since the same PLL circuit is clocking all four channels on the R-4. It will sound odd in the field since things are not aligned correctly, but once you get things into a DAW and get the delay set right, you'll be fine.

Wayne

[gratefulphish]

Thanks again.  +T for the help.

[poorlyconditioned]

I was hoping to avoid that sync issue between the V3 and the R-4 Pro. Am I going to have sync issues even if I run mics directly into the R-4 on two channels and the board on the other two, just because of the amount of wires and electronics in between?

The issue you're going to run into is the board is a bit ahead of the PA, which makes perfect sense when you think about it. Vocals and instruments on stage have to go back to the board, then get turned around and go back on stage where the PA is. The amount of delay that has to be added varies. With the R-4, you maintain four separate tracks (right?), so you tweak the delay in a multi-channel DAW later. The only problem in doing this is providing a 2-channel feed out. The DEVA allows you to set a delay in the unit. This delay is used for the output, so I still have to tweak shows later in post. However, it really does work out better because you never know exactly how much delay to add and when you're in the field it is very tough to get it exactly right. At festivals depending on location and distance I sometimes don't have enough delay in the DEVA (I only have 40 ms), but usually this isn't a problem because most of the time I can't feed people from the sources I have, or if I am feeding them, it's minus stage mics and the board.

Wayne

Let me clarify the delay issue:  There is (virtually) no delay through the wires, it is the sound coming (through air) from the speakers to the audience.  Add 1ms per foot you are from the PA.  So, if you want things to line up, measure your distance from the mics to the PA speakers and delay your soundboard signal by this much (in ms).  The R4 records tracks independently so you can do this in post as well.

My experience is anything up to 10 or 15ms is fine (as long as the delay is constant, not drifting).  After that you start to notice an "echo".  This is why a lot of people can do "on the fly" matrix recording with a mixer + two track recorder.  It works, but only if you are close to the PA and if you an monitor well (good headphones).

  Richard