Help? Mixpre into Beachtek DXA-8 into Sony HC1 at DVinfo.net

Patricia Lamm · April 21st, 2006, 10:33 AM

I'm having some problems with my audio configuration. The following works very well:

2 Sony wireless (805 series) mics going into a Beachtek DXA-8 (stereo setting), then going into a Sony HC1. I have the camera audio set on manual with 1/4 gain set, meters going to a max of -12 dB.

But when I try the following I get too much room noise and crackling on voices:

2 Sony wireless mics going into a Mixpre (set to Center output), with two cables then going into Beachtek, then going into a Sony HC1. I have the Mixpre gain at middle settings with limiters on, the Beachtek gains set at a low setting (a high setting makes too much noise) with limiters set to off, and the camera audio on manual, 1/4 gain setting, with meters going max of -12 dB. I calibrated using a tone from the Mixpre and all the settings seemed fine.

What am I doing wrong?

Eventually I want to mix the two wireless mics to send into one of the Beachtek inputs, and have a 3rd mic going into the second Beacktek input for ambient noise. Any help would be appreciated.

Patricia Lamm · April 21st, 2006, 01:03 PM

So I just partially answered my own question -- I gather that I need an in-line attenuator going from the mixpre to the Beachtek. I tried this and the results were much better. So my new questions are;

(1) is it OK to have the Beachtek volume down to nearly zero when the mixpre is going through it? That's what seems to be needed to get good results.

(2) Also, I used a 30 dB attenuator from the mixpre to the Beachtek, but felt like I could have used more. Would 40 dB be overkill? (I don't have a 40 dB attenuator to try).

Steve House · April 22nd, 2006, 09:32 AM

Quote:

Originally Posted by Patricia Lamm

So I just partially answered my own question -- I gather that I need an in-line attenuator going from the mixpre to the Beachtek. I tried this and the results were much better. So my new questions are;

(1) is it OK to have the Beachtek volume down to nearly zero when the mixpre is going through it? That's what seems to be needed to get good results.

(2) Also, I used a 30 dB attenuator from the mixpre to the Beachtek, but felt like I could have used more. Would 40 dB be overkill? (I don't have a 40 dB attenuator to try).

You're on the right track. The MixPre is putting out a professional line level (+4dB) signal while your Beachtek/Camera combo is expecting a mic level input that will be about 55 db BELOW the level you're sending it. If the camera had a line input you'd be sitting prety - just plug the Mixpre tape output (-10dB) into it through an adapter and you'd be in business. Unfortunately your camera doesn't appear to have anything except an external mic jack to you're stuck using attentuating pads. Take a look at the Shure A15LA Line Adapter that provides 50db attentuation. List @ $40 each and you'll need two.

Patricia Lamm · April 22nd, 2006, 03:27 PM

Thanks, Steve. That's exactly what I'll get.

David Ennis · April 23rd, 2006, 12:18 PM

Steve is right, but didn't mention that the MixPre also expects mic level input. Wireless systems oftern output line level, which the MixPre does not like at all. The DXA-8 will tolerate higher input levels than the MixPre, which is consistent with your experience. The MixPre clearly indicates input clipping with an amber/red LED, but you didn't mention that.

There is no harm in running the DXA-8 with the trim knob all the way down--that's actually -10 dB. Together with - 30 dB of external attenuation, that should bring the + 4dB signal from the MixPre under control, but another 10 dB of attenuation would give you more breathing room. I also don't see any reason not to use the Beach's limiters. Limiting in the MixPre doesn't prevent clipping in the camera's input.

The camera's input is oblivious to what has been done to the signal; it only cares that the size of the signal is appropriate, and the DXA-8's limited output range is appropriate for camcorder external mic inputs.

Patricia Lamm · April 23rd, 2006, 08:22 PM

Thanks for the additional information, Fred. I checked and my SONY WRR 805a is outputting mic level, so that part at least is working correctly. All these differences in levels and the need for inline pads has made me start looking at other mixers (since I just got the mixpre), ones which have both line/mic input/output levels (such as the Wendt X3 and the Sound Devices 302) andwhich would also add a 3rd channel if I needed it one day. But I think the portability of the mixpre will probably just keep me where I am for now.

David Ennis · April 23rd, 2006, 09:32 PM

The MixPre is a great little unit--I want one, and wouldn't mind using a -40 dB pad with it.

I'd just use a splitter to combine the two wireless signals and free up the the other DXA-8 input. If you decide do that, send me the MixPre, okay? 8>)

Patricia Lamm · April 23rd, 2006, 10:31 PM

Quote:

Originally Posted by Fred Retread

The MixPre is a great little unit--I want one, and wouldn't mind using a -40 dB pad with it.

I'd just use a splitter to combine the two wireless signals and free up the the other DXA-8 input. If you decide do that, send me the MixPre, okay? 8>)

Well, actually the whole reason I bought the MixPre is because I was told I shouldn't combine the two wireless signals into one input of the Beachtek using a splitter unless I wanted to get lousy results:

http://www.dvinfo.net/conf/showthread.php?t=64060

So I guess the MixPre will be staying at my house... ;-)

Steve House · April 24th, 2006, 03:36 AM

Quote:

Originally Posted by Patricia Lamm

Thanks for the additional information, Fred. I checked and my SONY WRR 805a is outputting mic level, so that part at least is working correctly. All these differences in levels and the need for inline pads has made me start looking at other mixers (since I just got the mixpre), ones which have both line/mic input/output levels (such as the Wendt X3 and the Sound Devices 302) andwhich would also add a 3rd channel if I needed it one day. But I think the portability of the mixpre will probably just keep me where I am for now.

You'll find the 302 is not much larger than the MixPre so you wouldn't sacrifice any portability by going to it. Actually, even if you go to a 302 I'd suggest hanging on to your MixPre because many SD mixers can be "daisy chained" and I believe the MixPre/302 can be connected together like that to give you a total of 5 mic inputs if you needed them.

I'm gonna stick to my guns regarding the inadvisability of using a simple "Y" adapter to combine two mono audio signals onto 1 mono channel. Two mono signals to a single stereo channel, yes, but not two mono feeds into a single mono channel. Combining your two wireless receivers to feed one mono input requires more than merely connecting them together in parallel.

Patricia Lamm · April 24th, 2006, 08:03 AM

Quote:

Originally Posted by Steve House

I'm gonna stick to my guns regarding the inadvisability of using a simple "Y" adapter to combine two mono audio signals onto 1 mono channel. Two mono signals to a single stereo channel, yes, but not two mono feeds into a single mono channel. Combining your two wireless receivers to feed one mono input requires more than merely connecting them together in parallel.

Actually, if a nifty little splitter were announced at NAB today which would solve all my problems, it wouldn't matter now. After hearing the quality of the MixPre I can't go back to using anything less. (This stuff is like crack, isn't it?)

Steve House · April 24th, 2006, 10:23 AM

Quote:

Originally Posted by Patricia Lamm

Actually, if a nifty little splitter were announced at NAB today which would solve all my problems, it wouldn't matter now. After hearing the quality of the MixPre I can't go back to using anything less. (This stuff is like crack, isn't it?)

Except unlike your friendly neighborhood dope dealer, the first taste ISN'T free! <grin> Sound Devices isn't only manufacturer of professional quality equipment but they are indisputably one of the serious players.

David Ennis · April 24th, 2006, 10:52 AM

Quote:

Originally Posted by Steve House

...I'm gonna stick to my guns regarding the inadvisability of using a simple "Y" adapter to combine two mono audio signals onto 1 mono channel. Two mono signals to a single stereo channel, yes, but not two mono feeds into a single mono channel...

Unless I miss my guess, I think we're both in the "theorist" category on this one, Steve 8>)

Steve House · April 24th, 2006, 12:20 PM

Quote:

Originally Posted by Fred Retread

Unless I miss my guess, I think we're both in the "theorist" category on this one, Steve 8>)

Haven't tried it with the hardware in question, true.

April 21st, 2006, 10:33 AM	#1
Patricia Lamm Regular Crew Join Date: Nov 2005 Location: Okemos, MI Posts: 174	Help? Mixpre into Beachtek DXA-8 into Sony HC1 I'm having some problems with my audio configuration. The following works very well: 2 Sony wireless (805 series) mics going into a Beachtek DXA-8 (stereo setting), then going into a Sony HC1. I have the camera audio set on manual with 1/4 gain set, meters going to a max of -12 dB. But when I try the following I get too much room noise and crackling on voices: 2 Sony wireless mics going into a Mixpre (set to Center output), with two cables then going into Beachtek, then going into a Sony HC1. I have the Mixpre gain at middle settings with limiters on, the Beachtek gains set at a low setting (a high setting makes too much noise) with limiters set to off, and the camera audio on manual, 1/4 gain setting, with meters going max of -12 dB. I calibrated using a tone from the Mixpre and all the settings seemed fine. What am I doing wrong? Eventually I want to mix the two wireless mics to send into one of the Beachtek inputs, and have a 3rd mic going into the second Beacktek input for ambient noise. Any help would be appreciated.

April 23rd, 2006, 12:18 PM	#5
David Ennis Fred Retread Join Date: Jul 2004 Location: Hartford, CT Posts: 1,227	Steve is right, but didn't mention that the MixPre also expects mic level input. Wireless systems oftern output line level, which the MixPre does not like at all. The DXA-8 will tolerate higher input levels than the MixPre, which is consistent with your experience. The MixPre clearly indicates input clipping with an amber/red LED, but you didn't mention that. There is no harm in running the DXA-8 with the trim knob all the way down--that's actually -10 dB. Together with - 30 dB of external attenuation, that should bring the + 4dB signal from the MixPre under control, but another 10 dB of attenuation would give you more breathing room. I also don't see any reason not to use the Beach's limiters. Limiting in the MixPre doesn't prevent clipping in the camera's input. The camera's input is oblivious to what has been done to the signal; it only cares that the size of the signal is appropriate, and the DXA-8's limited output range is appropriate for camcorder external mic inputs. __________________ "Nothing in the world can take the place of persistence..." - Calvin Coolidge "My brain is wired to want to know how other things are wired." - Me

April 23rd, 2006, 09:32 PM	#7
David Ennis Fred Retread Join Date: Jul 2004 Location: Hartford, CT Posts: 1,227	The MixPre is a great little unit--I want one, and wouldn't mind using a -40 dB pad with it. I'd just use a splitter to combine the two wireless signals and free up the the other DXA-8 input. If you decide do that, send me the MixPre, okay? 8>) __________________ "Nothing in the world can take the place of persistence..." - Calvin Coolidge "My brain is wired to want to know how other things are wired." - Me

April 21st, 2006, 01:03 PM	#2
Patricia Lamm Regular Crew Join Date: Nov 2005 Location: Okemos, MI Posts: 174	So I just partially answered my own question -- I gather that I need an in-line attenuator going from the mixpre to the Beachtek. I tried this and the results were much better. So my new questions are; (1) is it OK to have the Beachtek volume down to nearly zero when the mixpre is going through it? That's what seems to be needed to get good results. (2) Also, I used a 30 dB attenuator from the mixpre to the Beachtek, but felt like I could have used more. Would 40 dB be overkill? (I don't have a 40 dB attenuator to try).

April 22nd, 2006, 03:27 PM	#4
Patricia Lamm Regular Crew Join Date: Nov 2005 Location: Okemos, MI Posts: 174	Thanks, Steve. That's exactly what I'll get.

April 23rd, 2006, 08:22 PM	#6
Patricia Lamm Regular Crew Join Date: Nov 2005 Location: Okemos, MI Posts: 174	Thanks for the additional information, Fred. I checked and my SONY WRR 805a is outputting mic level, so that part at least is working correctly. All these differences in levels and the need for inline pads has made me start looking at other mixers (since I just got the mixpre), ones which have both line/mic input/output levels (such as the Wendt X3 and the Sound Devices 302) andwhich would also add a 3rd channel if I needed it one day. But I think the portability of the mixpre will probably just keep me where I am for now.