SRa gain staging/metering

[Josh Tucker]

Hey guys. I recently purchased a Lectro SRa for use as a camera hop, and took it out for the first time a few days ago. It was fed by 2 SMQV's, which in turn were fed by the line level outs of my 788. I left the gain of the 788 output at -4dB and set both the tx's and rx gain to zero. When I did this, I noticed that the metering on the SRa seemed really hot, while the meters on the tx's were barely hitting above -20. Did I get something mixed up with the gain staging here, or am I just misreading meters on the SRa (I haven't found anything in the manual about the meter scale)? Seems like the metering on the tx's should be more or less identical to the rx, assuming that there's no additional gain applied to the rx. Right?

[VASI]

I left the gain of the 788 output at -4dB and set both the tx's and rx gain to zero.

When I did this, I noticed that the metering on the SRa seemed really hot, while the meters on the tx's were barely hitting above -20.

Of course you didn't found anything in manual because the manual is not the manual

for the sound mixer job.

Thirst of all. Why to left the gain from 788T to -4dB?

My two questions is about your "red" line.

And my third question is about "what camera".

Help me to answer you.

[Josh Tucker]

Sorry if I was unclear. I wasn't trying to consult a manual on how to do my job. I was merely referring to the lack of markings for the meters on the SRa. For comparison, when I run -20dB tone through a tx and to a 411a, I can clearly see whether the meter is hitting the -20 mark on the outer rim of the display. The SRa has no such markings.

Regarding the -4dB output on the 788: I generally attenuate my output to camera by a few dB to avoid hitting the cameras limiters when things get loud. I find that any limiting that may occur is best left to the 788.

Not sure what you meant by my "red line". Were you referring to how hot I'm mixing to the tx's? Or how I'm judging what's "too hot" on the SRa?

As for the camera, it doesn't really enter into this equation, as my issues are happening before I hit camera. If you must know though, it was a Sony FX100.

Thanks for responding. Any help is greatly appreciated. I'm working with the same client next week and want to make sure I've got this sorted beforehand.

[LarryF]

The SRa (or UCR411a) can never be set to high in the sense that it always runs at full level internally and you then attenuate the signal with the SRa "gain" to match to whatever device you are going into. There is no downside whatsoever to running the SRa wide open and adjusting the mixer or recorder to match the wide open level. Or attenuate the SRa signal if necessary to match a high gain input keeping in mind that weak signals are asking for ground loops. The audio meter on the SRa indicates the modulation level in the transmitter and has nothing, nada, and/or zero to do with attenuation (gain) settings at the SRa.

Read the manual on how to set the gain of the transmitter. Ninety-nine percent of the time it is set too low. The reason that even 1% set the gain correctly is that they read JW Sound.

Best Regards,

Larry Fisher

Lectrosonics

[RadoStefanov]

I run +5 line level on all my Lectrosonics.

Line level servo 20K to pin 5 hop cable.

-10 output level.

[Marc Wielage]

I just use a line level input cable and pad it down so it doesn't overload the SMQV transmitter. I'll let the peaks hit the red a little bit (as per the manual). Once I do that, I just adjust the output of the SRa receiver so that -20dBfs is about in the middle of the range of the camera's audio level meter. 90% of the time, I worry much more about overloading the camera input stage than I worry about what the Lectro is doing. Some of those analog camera stages are really prone to distortion.

[VM]

Read the manual on how to set the gain of the transmitter. Ninety-nine percent of the time it is set too low.

I wonder what is the led correspondance to dBfs. For example if I send a -20 dBfs tone from the 788 to the SMQV, should I hit the red led a little bit ? Is it 20 dB before clipping ? That would be so simple and precise to set the transmitter with tone.

[Jon Gilbert]

The reason that even 1% set the gain correctly is that they read JW Sound.

Best Regards,

Larry Fisher

Lectrosonics

Brilliant Larry, just made me spit Flying Dog IPA all over the laptop!

[VASI]

Sorry if I was unclear. I wasn't trying to consult a manual on how to do my job. I was merely referring to the lack of markings for the meters on the SRa. For comparison, when I run -20dB tone through a tx and to a 411a, I can clearly see whether the meter is hitting the -20 mark on the outer rim of the display. The SRa has no such markings.

Regarding the -4dB output on the 788: I generally attenuate my output to camera by a few dB to avoid hitting the cameras limiters when things get loud. I find that any limiting that may occur is best left to the 788.

Not sure what you meant by my "red line". Were you referring to how hot I'm mixing to the tx's? Or how I'm judging what's "too hot" on the SRa?

As for the camera, it doesn't really enter into this equation, as my issues are happening before I hit camera. If you must know though, it was a Sony FX100.

Thanks for responding. Any help is greatly appreciated. I'm working with the same client next week and want to make sure I've got this sorted beforehand.

1: http://www.bhphotovideo.com/lit_files/1563.pdf (page 73). Must see about Audio Limit.

2: What output type use for Tx? Unbalanced (5/6 output) or the TA3 (1,2,3,4 output)?

3: I believe cover me the Larry F, Rado Stefanov and Marc Wielage.

Sorry for late response.

[Wyatt Tuzo]

What input cable are you using for your transmitters? If you're feeding a line level signal, you should be using an MC35. If you are using an MC40 or 41, you'd have to feed it mic level for it to modulate properly.

Double check your input cable wiring... It sounds to me that that is likely your issue

[Josh Tucker]

What input cable are you using for your transmitters? If you're feeding a line level signal, you should be using an MC35. If you are using an MC40 or 41, you'd have to feed it mic level for it to modulate properly.

Double check your input cable wiring... It sounds to me that that is likely your issue

I'm definitely using line level cables. Had the guys at Pro Sound put them together for me, and I checked them yesterday to make extra sure.

It seems that my main problem was that I misinterpreted the meters on the SRa, and didn't give the tx's or rx enough gain. I've since run tone through the system and adjusted settings accordingly. I'm pretty sure I've got everything set, but will know for sure when I'm back with the same client this Friday. Thanks for all the help guys!

[RadoStefanov]

Run -10 output and -20 tone to the TX. volume up to where both green lights are on. Then just volume down till one of the green lights stops lighting . I use this setup and it gives me plenty of headroom

[Jason A]

This is the exact same workflow I use and it has served me well, but I think it is still a bit conservative according to the SMQv manual recommendation.

Run -10 output and -20 tone to the TX. volume up to where both green lights are on. Then just volume down till one of the green lights stops lighting . I use this setup and it gives me plenty of headroom

[RadoStefanov]

It works well for me. Picks on camera are -10.

Sent from my HD7 T9292 using Board Express

[VM]

-20 tone to the TX. volume up to where both green lights are on. Then just volume down till one of the green lights stops lighting .

So is it the -20 dBfs of the TX ?

[Josh Tucker]

-20 tone to the TX. volume up to where both green lights are on. Then just volume down till one of the green lights stops lighting .

So is it the -20 dBfs of the TX ?

You would be at -20dB. NOT "dBfs", as you're still in the analog domain.

[RadoStefanov]