JuicedLink or 40dB pad? at DVinfo.net

David Trayers · March 14th, 2009, 01:40 PM

I shoot mostly dance recitals. I shoot with a GL2 and use a JuicedLink 211 to get a feed from the mixer board to the camera. It worked well knocking down the line level to mic levels.

I've had a couple of mishaps in the past with board techs changing the mix or not being able to mix a house and stage mic into my feed, so I got a small mixer to add my own house and stage mics. So now I just get the music feed from the board on one of the subs and do my own mixing. I have the board tech set his feed to unity and I control the rest from my board.

My question is, since I'm still going through the preamps on the camera, is there any advantage in using the JuicedLink? Wouldn't a 40dB or 50dB pad between the mix board and the camera do the same? I was thinking that with a 40dB pad, I could adjust the feed from my mixer board to be a little hotter than normal mic levels and set the manual audio gains on the camera to a low level to reduce noise from the camera's preamps. That's basically how I set the GL2 up with the JuicedLink.

Jay Massengill · March 14th, 2009, 02:46 PM

Theoretically yes, a pad would serve the same function. But in practice, isn't it easier to make the physical connection using the JuicedLink and allow longer balanced cable runs and locking connectors with a box that's securely attached to the camera?

Marco Leavitt · March 14th, 2009, 07:36 PM

I haven't used the Juicedlink, but in practice I'd say it's best to eliminate extra electronics between the board and the camera. I'd just get a passive mixer and either use the line input switch, or add a 40 dB pad as you suggest. That's assuming you're getting a genuine line level signal from the board. My experience with those is that the operator often has no idea what he/she is feeding you.

Brian Boyko · March 15th, 2009, 03:56 AM

It may depend on the camera, but the preamps I've used in the HV20 and the HG20 have been very "noisy," and turning them up introduced a lot of hiss. The main reason I use the Juicedlink is so that I can turn down the preamp volume in the camera.

This may not be a problem with prosumer cameras, but they mostly have their own XLR inputs anyway.

Marco Leavitt · March 15th, 2009, 06:52 AM

Well, you would normally use a 54 dB pad when going from line level to mic level, so using a 40 dB pad would give you a very hot mic level signal that should allow you to keep the camera gain down to a decent level. Adding a pre-amp to the chain in this situation won't buy you anything, as you can't feed the camera a much hotter signal without risking distortion because of the impedance mismatch. That's why some people use an external pad with their XLR adapters rather than just flipping the line input switch. But, as I said, it can be difficult to know what signal they are feeding you from the board. The hardest thing to deal with is an unbalanced consumer line level signal.

Chris Rackauckas · March 15th, 2009, 02:22 PM

Just try it out. I have one of the 40db pads from this guy and they work great for me. $12 each.

Naiant Studio Store - Clever Devices

David Trayers · March 15th, 2009, 06:43 PM

Thanks for the thoughtful replies. I'm not so concerned about cables pulling out as I tape everything in place with gaffer tape (leaving the appropriate slack).

I agree, many times the board tech doesn't know how to give me a proper feed. That's why I bring my own mixer now. I shoot mostly in high schools where the board tech is usually a student. Luckily, I'm somewhat familar with the general operation of analog mixers and can usually coach them in how to send the music to an empty sub channel and adjust it to around to 0dB. I send that to my board and add a mic for the house and sometimes I run a wireless to the edge of the stage if there will be tap dancing.

I did a little experimenting over the weekend. I tried a couple of setups using classical music (Tchaikovsky, "Swan Lake") from a CD as the audio source and recorded it to tape. I adjusted the gain so the resulting feed to the board peaked at 0dB and kept the main out at unity. I ran it several times and the pulled the video from the tape into the computer.

Indeed, a feed from my board's XLR out with a 40dB pad works nicely. I can set the manual audio controls on the camera to about 25% of full range and on the camera's meter the signal is just at -12dB. The loudest passages just go into the yellow. At one point during the recording I muted the channel so I recorded silence. When listening to the recording on the computer there is just the hint of hiss when I turn up the volume on my headphones.

However, the comments about balanced vs. unbalanced brings up another question. I would think that I would enjoy the benefits of a balanced run if I ran XLR from the board to the camera, then added the pad, then a short (2') XLR to 1/8 mini-plug for the camera mic input?

In other words, does having part of the run unbalanced make the whole thing unbalanced, or just the non-XLR part?

Marco Leavitt · March 15th, 2009, 07:29 PM

You are correct that you don't want to unbalance the connection at the beginning of the run. You do it at the camera. Also, you want the attenuator at the camera end as well so that you have a line level signal for most of the length of the run. It's much safer from RF interference that way. You have to be careful about which adapter you use, as some of the cheaper ones will leave the entire line unbalanced, as you suspect. A quality transformer balanced adapter should keep the signal balanced up to the point that you unbalance it.

Steve House · March 16th, 2009, 07:39 AM

Adding an FYI note to Marco's comments ... notice he said "transformer balanced adapter" to convert a balanced feed to unbalanced for input to the camera. That would be an adapter like a Beachtek or an inline impedance matching transformer such as those from Shure. One often sees people try to save money by unbalancing the XLR line by wiring up a simple adapter cable that connects XLR-2 (signal +) to TRS or TS tip (hot) and both XLR-3 (signal -) and XLR-1 (ground) to the TRS/TS sleeve (ground). That works, but careful if you try that approach since unbalancing by simply grounding the signal cold (at either end) unbalances the entire system and you lose the noise immunity advantages that one would expect to have using a balanced XLR cable as well as introducing a 6dB loss of signal level.

March 14th, 2009, 01:40 PM	#1
David Trayers Regular Crew Join Date: Feb 2007 Location: Hastings, MN Posts: 51	JuicedLink or 40dB pad? I shoot mostly dance recitals. I shoot with a GL2 and use a JuicedLink 211 to get a feed from the mixer board to the camera. It worked well knocking down the line level to mic levels. I've had a couple of mishaps in the past with board techs changing the mix or not being able to mix a house and stage mic into my feed, so I got a small mixer to add my own house and stage mics. So now I just get the music feed from the board on one of the subs and do my own mixing. I have the board tech set his feed to unity and I control the rest from my board. My question is, since I'm still going through the preamps on the camera, is there any advantage in using the JuicedLink? Wouldn't a 40dB or 50dB pad between the mix board and the camera do the same? I was thinking that with a 40dB pad, I could adjust the feed from my mixer board to be a little hotter than normal mic levels and set the manual audio gains on the camera to a low level to reduce noise from the camera's preamps. That's basically how I set the GL2 up with the JuicedLink.

March 15th, 2009, 03:56 AM	#4
Brian Boyko Major Player Join Date: Dec 2006 Location: Austin, TX Posts: 773	It may depend on the camera, but the preamps I've used in the HV20 and the HG20 have been very "noisy," and turning them up introduced a lot of hiss. The main reason I use the Juicedlink is so that I can turn down the preamp volume in the camera. This may not be a problem with prosumer cameras, but they mostly have their own XLR inputs anyway. __________________ Equip: Panny GH1, Canon HG20, Juicedlink, AT897, Sennh. EW/GW100, Zoom H2, Vegas 8.1

March 16th, 2009, 07:39 AM	#9
Steve House Inner Circle Join Date: Mar 2005 Location: Hamilton, Ontario, Canada Posts: 5,742	Adding an FYI note to Marco's comments ... notice he said "transformer balanced adapter" to convert a balanced feed to unbalanced for input to the camera. That would be an adapter like a Beachtek or an inline impedance matching transformer such as those from Shure. One often sees people try to save money by unbalancing the XLR line by wiring up a simple adapter cable that connects XLR-2 (signal +) to TRS or TS tip (hot) and both XLR-3 (signal -) and XLR-1 (ground) to the TRS/TS sleeve (ground). That works, but careful if you try that approach since unbalancing by simply grounding the signal cold (at either end) unbalances the entire system and you lose the noise immunity advantages that one would expect to have using a balanced XLR cable as well as introducing a 6dB loss of signal level. __________________ Good news, Cousins! This week's chocolate ration is 15 grams!

March 14th, 2009, 02:46 PM	#2
Jay Massengill Trustee Join Date: Jul 2003 Location: Burlington Posts: 1,976	Theoretically yes, a pad would serve the same function. But in practice, isn't it easier to make the physical connection using the JuicedLink and allow longer balanced cable runs and locking connectors with a box that's securely attached to the camera?

March 14th, 2009, 07:36 PM	#3
Marco Leavitt Inner Circle Join Date: Jul 2002 Location: Albany, NY 12210 Posts: 2,652	I haven't used the Juicedlink, but in practice I'd say it's best to eliminate extra electronics between the board and the camera. I'd just get a passive mixer and either use the line input switch, or add a 40 dB pad as you suggest. That's assuming you're getting a genuine line level signal from the board. My experience with those is that the operator often has no idea what he/she is feeding you.

March 15th, 2009, 06:52 AM	#5
Marco Leavitt Inner Circle Join Date: Jul 2002 Location: Albany, NY 12210 Posts: 2,652	Well, you would normally use a 54 dB pad when going from line level to mic level, so using a 40 dB pad would give you a very hot mic level signal that should allow you to keep the camera gain down to a decent level. Adding a pre-amp to the chain in this situation won't buy you anything, as you can't feed the camera a much hotter signal without risking distortion because of the impedance mismatch. That's why some people use an external pad with their XLR adapters rather than just flipping the line input switch. But, as I said, it can be difficult to know what signal they are feeding you from the board. The hardest thing to deal with is an unbalanced consumer line level signal.

March 15th, 2009, 02:22 PM	#6
Chris Rackauckas Regular Crew Join Date: Feb 2009 Location: USA Posts: 113	Just try it out. I have one of the 40db pads from this guy and they work great for me. $12 each. Naiant Studio Store - Clever Devices

March 15th, 2009, 06:43 PM	#7
David Trayers Regular Crew Join Date: Feb 2007 Location: Hastings, MN Posts: 51	Thanks for the thoughtful replies. I'm not so concerned about cables pulling out as I tape everything in place with gaffer tape (leaving the appropriate slack). I agree, many times the board tech doesn't know how to give me a proper feed. That's why I bring my own mixer now. I shoot mostly in high schools where the board tech is usually a student. Luckily, I'm somewhat familar with the general operation of analog mixers and can usually coach them in how to send the music to an empty sub channel and adjust it to around to 0dB. I send that to my board and add a mic for the house and sometimes I run a wireless to the edge of the stage if there will be tap dancing. I did a little experimenting over the weekend. I tried a couple of setups using classical music (Tchaikovsky, "Swan Lake") from a CD as the audio source and recorded it to tape. I adjusted the gain so the resulting feed to the board peaked at 0dB and kept the main out at unity. I ran it several times and the pulled the video from the tape into the computer. Indeed, a feed from my board's XLR out with a 40dB pad works nicely. I can set the manual audio controls on the camera to about 25% of full range and on the camera's meter the signal is just at -12dB. The loudest passages just go into the yellow. At one point during the recording I muted the channel so I recorded silence. When listening to the recording on the computer there is just the hint of hiss when I turn up the volume on my headphones. However, the comments about balanced vs. unbalanced brings up another question. I would think that I would enjoy the benefits of a balanced run if I ran XLR from the board to the camera, then added the pad, then a short (2') XLR to 1/8 mini-plug for the camera mic input? In other words, does having part of the run unbalanced make the whole thing unbalanced, or just the non-XLR part?

March 15th, 2009, 07:29 PM	#8
Marco Leavitt Inner Circle Join Date: Jul 2002 Location: Albany, NY 12210 Posts: 2,652	You are correct that you don't want to unbalance the connection at the beginning of the run. You do it at the camera. Also, you want the attenuator at the camera end as well so that you have a line level signal for most of the length of the run. It's much safer from RF interference that way. You have to be careful about which adapter you use, as some of the cheaper ones will leave the entire line unbalanced, as you suspect. A quality transformer balanced adapter should keep the signal balanced up to the point that you unbalance it.