I need some "Sound" advice at DVinfo.net

Frank Maggi · December 9th, 2005, 11:36 AM

I am not a real accomplished audio person (a little knowledge is a dangerous thing), and I need some knowledgeable advice. My audio set up is Senn G2 lav or ME 66 shotgun, both usually sent wireless (transmitter at -10 db) to a PSC Promix 3 field mixer (receiver sensitivity set to - 24 db), then line level to a Beachtek DXA 4C which is connected via supplied RCAs into Audio one of a Canon XL 1 (not S) at line level.

I’ve been told the mixer spits out pro level +4 dbu signal and I need a 30 or 35 db attenuator before going into the Beachtek/Canon. Currently I’m not doing this. It sounds pretty good to me although peaks seem pretty brittle (despite the mixers limiter). The mics don’t show clipping on the transmitter and the mixer is usually set between 11 and 12 o’clock, trying to keep the 0 db light from ever coming on. The audio meters on the Canon don’t look overly hot. Should I leave well enough alone or should I tone down the signal from mixer to camera? If so, any suggestions on what/where to buy? Jay Rose’s book has a section on how to build one but my hands were not meant for soldering irons. Again, I know just enough to know I don’t know much. I’d appreciate any help from someone who actually understands. Thanks.

Marco Leavitt · December 9th, 2005, 12:03 PM

I believe the RCA inputs are looking for consumer line level of -10dBV. If the PSC mixer is indeed a +4dBu output the difference in decibels is more like 12, not the 14 you would expect because they're different scales.

http://www.dv.com/news/news_item.jht.../2003/rose0303

I was under the impression that you could change the output on that mixer though, so you should check into that. I'm surprised the Beachtek doesn't have an attenuator switch, although it would probably be -54db.

To make things even more confusing, Jay Rose recommends -30 dBV for the RCA inputs to maximize the signal to noise ratio on that camera, but I haven't tried it.

Jay Massengill · December 9th, 2005, 12:55 PM

As Marco mentioned there are several different ways to add some attenuation.
If we work backwards from a goal of using the XL-1 set for Mic ATT and sending it a hot mic signal (approx. -30db), that's pretty easy to do using a mixer and a BeachTek.
A BeachTek set for line-level input doesn't attenuate as much as you might think if you have the rotary controls up full. Using a full line-level mixer output into the BeachTek set for line-level usually gives you what you need to set the XL-1 to Mic ATT and be close to your target. That's what I do often with a friend's XL-1 with my BeachTek DXA-6 and either a SoundDevices MixPre or a Mackie 1202 or 1402.
I have a ProMix 3 but I haven't tried it in this situation. The original versions had a 0db line out but I think they were going to change this to +4db at some point. Do you know which you have?
You can also drop the PSC output to mic level, but I would keep it at line and set the BeachTek to line level and the camera to Mic ATT. Test that out and see if you can get low noise recordings without overloading the input on peaks. Remember that the XL-1 meters won't show that you're overloading the input. They just indicate what level of signal you're recording to tape, not whether you've overdriven the input before the signal gets to the recording controls and meters. You have to listen to the camera to catch this problem. You may want to get a 3-output battery-powered headphone amp from Radio Shack, it's very helpful with the XL-1.
The ProMix 3 inputs aren't nearly as clean as the MixPre or Mackie inputs, but that shouldn't be a surprise given all the features they've crammed in at that price point. Fortunately you have two mics that are capable of hot output. Just make sure you've got the relationship right between your mics and the mixer input switch settings, achieving low noise without overloading before you send the output to the BeachTek.

Frank Maggi · December 9th, 2005, 04:18 PM

Thanks to both of you for the excellent advice. Jay, I believe I have the earlier Promix 3 with the 0db level. I hope this is not too naive, but do I have to monitor through a headphone amp? Can't I monitor from the XL 1 phone jack or through the mixer using tape return? And however I monitor, is what I hear going in a reliable indication of what is going to come out? Again, thanks for the expert advice; I work for an elementary school district and we don't have the personnel to answer these questions nor the budget to bring it in.

Marco Leavitt · December 9th, 2005, 04:30 PM

I have one of those Radio Shack headphone splitter thingys and I'm not crazy about it. Keep the headphone volume at about 50 percent and it should be a pretty reliable indication of what's recording to tape, although supposedly the headphone output on all of these camcorders is pre-AD conversion. It never sounds quite as good when you play it back.

Jay Massengill · December 9th, 2005, 10:00 PM

On his XL-1, even with the headphone volume all the way up and sensitive low-impedence headphones, you can barely hear a signal while recording. It's distinctly lower in volume than when listening to playback.
I find it a necessity to have the amp with his camera. It does plug into the camera's headphone jack and gives 3 amplified outputs. Other than the fact that it creates a much more powerful signal, which could blow your head off if you don't adjust the headphone volume, I haven't noted any problems.
What don't you like about yours Marco?
I don't remember if the mixer's tape return can handle a headphone signal from the camera. I don't think you can use the RCA outs of the XL-1 to monitor during shooting like you can on the DVX-100a because on the Canon they also serve as inputs while in camera mode. On the DVX the RCA's only become inputs during VCR mode.

Marco Leavitt · December 9th, 2005, 10:53 PM

I just don't trust it. If I hear distortion I can't tell if it's coming from the camera's headphone jack or the external booster. It also has a lot of background hiss and it makes me nervous, since I can't be certain that it's not recording to tape. Also, I don't want to encourage the director and DP to listen on headphones. It's a nuisance. :) I did use one on occasion until we got a 302, which has a pretty good monitor input. We also have a SignVideo external meter with a headphone boost that I like quite a lot, but it's obviously a lot more expensive than the Radio Shack doo-dad.

December 9th, 2005, 11:36 AM	#1
Frank Maggi New Boot Join Date: Oct 2005 Location: Valley Center, CA Posts: 14	I need some "Sound" advice I am not a real accomplished audio person (a little knowledge is a dangerous thing), and I need some knowledgeable advice. My audio set up is Senn G2 lav or ME 66 shotgun, both usually sent wireless (transmitter at -10 db) to a PSC Promix 3 field mixer (receiver sensitivity set to - 24 db), then line level to a Beachtek DXA 4C which is connected via supplied RCAs into Audio one of a Canon XL 1 (not S) at line level. I’ve been told the mixer spits out pro level +4 dbu signal and I need a 30 or 35 db attenuator before going into the Beachtek/Canon. Currently I’m not doing this. It sounds pretty good to me although peaks seem pretty brittle (despite the mixers limiter). The mics don’t show clipping on the transmitter and the mixer is usually set between 11 and 12 o’clock, trying to keep the 0 db light from ever coming on. The audio meters on the Canon don’t look overly hot. Should I leave well enough alone or should I tone down the signal from mixer to camera? If so, any suggestions on what/where to buy? Jay Rose’s book has a section on how to build one but my hands were not meant for soldering irons. Again, I know just enough to know I don’t know much. I’d appreciate any help from someone who actually understands. Thanks.

December 9th, 2005, 12:03 PM	#2
Marco Leavitt Inner Circle Join Date: Jul 2002 Location: Albany, NY 12210 Posts: 2,652	I believe the RCA inputs are looking for consumer line level of -10dBV. If the PSC mixer is indeed a +4dBu output the difference in decibels is more like 12, not the 14 you would expect because they're different scales. http://www.dv.com/news/news_item.jht.../2003/rose0303 I was under the impression that you could change the output on that mixer though, so you should check into that. I'm surprised the Beachtek doesn't have an attenuator switch, although it would probably be -54db. To make things even more confusing, Jay Rose recommends -30 dBV for the RCA inputs to maximize the signal to noise ratio on that camera, but I haven't tried it.

December 9th, 2005, 12:55 PM	#3
Jay Massengill Trustee Join Date: Jul 2003 Location: Burlington Posts: 1,976	As Marco mentioned there are several different ways to add some attenuation. If we work backwards from a goal of using the XL-1 set for Mic ATT and sending it a hot mic signal (approx. -30db), that's pretty easy to do using a mixer and a BeachTek. A BeachTek set for line-level input doesn't attenuate as much as you might think if you have the rotary controls up full. Using a full line-level mixer output into the BeachTek set for line-level usually gives you what you need to set the XL-1 to Mic ATT and be close to your target. That's what I do often with a friend's XL-1 with my BeachTek DXA-6 and either a SoundDevices MixPre or a Mackie 1202 or 1402. I have a ProMix 3 but I haven't tried it in this situation. The original versions had a 0db line out but I think they were going to change this to +4db at some point. Do you know which you have? You can also drop the PSC output to mic level, but I would keep it at line and set the BeachTek to line level and the camera to Mic ATT. Test that out and see if you can get low noise recordings without overloading the input on peaks. Remember that the XL-1 meters won't show that you're overloading the input. They just indicate what level of signal you're recording to tape, not whether you've overdriven the input before the signal gets to the recording controls and meters. You have to listen to the camera to catch this problem. You may want to get a 3-output battery-powered headphone amp from Radio Shack, it's very helpful with the XL-1. The ProMix 3 inputs aren't nearly as clean as the MixPre or Mackie inputs, but that shouldn't be a surprise given all the features they've crammed in at that price point. Fortunately you have two mics that are capable of hot output. Just make sure you've got the relationship right between your mics and the mixer input switch settings, achieving low noise without overloading before you send the output to the BeachTek.

December 9th, 2005, 04:18 PM	#4
Frank Maggi New Boot Join Date: Oct 2005 Location: Valley Center, CA Posts: 14	Thanks to both of you for the excellent advice. Jay, I believe I have the earlier Promix 3 with the 0db level. I hope this is not too naive, but do I have to monitor through a headphone amp? Can't I monitor from the XL 1 phone jack or through the mixer using tape return? And however I monitor, is what I hear going in a reliable indication of what is going to come out? Again, thanks for the expert advice; I work for an elementary school district and we don't have the personnel to answer these questions nor the budget to bring it in.

December 9th, 2005, 04:30 PM	#5
Marco Leavitt Inner Circle Join Date: Jul 2002 Location: Albany, NY 12210 Posts: 2,652	I have one of those Radio Shack headphone splitter thingys and I'm not crazy about it. Keep the headphone volume at about 50 percent and it should be a pretty reliable indication of what's recording to tape, although supposedly the headphone output on all of these camcorders is pre-AD conversion. It never sounds quite as good when you play it back.

December 9th, 2005, 10:00 PM	#6
Jay Massengill Trustee Join Date: Jul 2003 Location: Burlington Posts: 1,976	On his XL-1, even with the headphone volume all the way up and sensitive low-impedence headphones, you can barely hear a signal while recording. It's distinctly lower in volume than when listening to playback. I find it a necessity to have the amp with his camera. It does plug into the camera's headphone jack and gives 3 amplified outputs. Other than the fact that it creates a much more powerful signal, which could blow your head off if you don't adjust the headphone volume, I haven't noted any problems. What don't you like about yours Marco? I don't remember if the mixer's tape return can handle a headphone signal from the camera. I don't think you can use the RCA outs of the XL-1 to monitor during shooting like you can on the DVX-100a because on the Canon they also serve as inputs while in camera mode. On the DVX the RCA's only become inputs during VCR mode.

December 9th, 2005, 10:53 PM	#7
Marco Leavitt Inner Circle Join Date: Jul 2002 Location: Albany, NY 12210 Posts: 2,652	I just don't trust it. If I hear distortion I can't tell if it's coming from the camera's headphone jack or the external booster. It also has a lot of background hiss and it makes me nervous, since I can't be certain that it's not recording to tape. Also, I don't want to encourage the director and DP to listen on headphones. It's a nuisance. :) I did use one on occasion until we got a 302, which has a pretty good monitor input. We also have a SignVideo external meter with a headphone boost that I like quite a lot, but it's obviously a lot more expensive than the Radio Shack doo-dad.