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

Go Back   DV Info Net > The Tools of DV and HD Production > All Things Audio

All Things Audio
Everything Audio, from acquisition to postproduction.


Reply
 
Thread Tools Search this Thread
Old April 21st, 2006, 11:33 AM   #1
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.
Patricia Lamm is offline   Reply With Quote
Old April 21st, 2006, 02:03 PM   #2
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).
Patricia Lamm is offline   Reply With Quote
Old April 22nd, 2006, 10:32 AM   #3
Inner Circle
 
Join Date: Mar 2005
Location: Hamilton, Ontario, Canada
Posts: 5,742
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.
__________________
Good news, Cousins! This week's chocolate ration is 15 grams!
Steve House is offline   Reply With Quote
Old April 22nd, 2006, 04:27 PM   #4
Regular Crew
 
Join Date: Nov 2005
Location: Okemos, MI
Posts: 174
Thanks, Steve. That's exactly what I'll get.
Patricia Lamm is offline   Reply With Quote
Old April 23rd, 2006, 01:18 PM   #5
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
David Ennis is offline   Reply With Quote
Old April 23rd, 2006, 09:22 PM   #6
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.
Patricia Lamm is offline   Reply With Quote
Old April 23rd, 2006, 10:32 PM   #7
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
David Ennis is offline   Reply With Quote
Old April 23rd, 2006, 11:31 PM   #8
Regular Crew
 
Join Date: Nov 2005
Location: Okemos, MI
Posts: 174
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... ;-)
Patricia Lamm is offline   Reply With Quote
Old April 24th, 2006, 04:36 AM   #9
Inner Circle
 
Join Date: Mar 2005
Location: Hamilton, Ontario, Canada
Posts: 5,742
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.
__________________
Good news, Cousins! This week's chocolate ration is 15 grams!
Steve House is offline   Reply With Quote
Old April 24th, 2006, 09:03 AM   #10
Regular Crew
 
Join Date: Nov 2005
Location: Okemos, MI
Posts: 174
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?)
Patricia Lamm is offline   Reply With Quote
Old April 24th, 2006, 11:23 AM   #11
Inner Circle
 
Join Date: Mar 2005
Location: Hamilton, Ontario, Canada
Posts: 5,742
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.
__________________
Good news, Cousins! This week's chocolate ration is 15 grams!
Steve House is offline   Reply With Quote
Old April 24th, 2006, 11:52 AM   #12
Fred Retread
 
Join Date: Jul 2004
Location: Hartford, CT
Posts: 1,227
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>)
__________________
"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
David Ennis is offline   Reply With Quote
Old April 24th, 2006, 01:20 PM   #13
Inner Circle
 
Join Date: Mar 2005
Location: Hamilton, Ontario, Canada
Posts: 5,742
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.
__________________
Good news, Cousins! This week's chocolate ration is 15 grams!
Steve House is offline   Reply
Reply

DV Info Net refers all where-to-buy and where-to-rent questions exclusively to these trusted full line dealers and rental houses...

Professional Video
(800) 833-4801
Portland, OR

B&H Photo Video
(866) 521-7381
New York, NY

Z.G.C.
(973) 335-4460
Mountain Lakes, NJ

Abel Cine Tech
(888) 700-4416
N.Y. NY & L.A. CA

Precision Camera
(800) 677-1023
Austin, TX

DV Info Net also encourages you to support local businesses and buy from an authorized dealer in your neighborhood.
  You are here: DV Info Net > The Tools of DV and HD Production > All Things Audio

Thread Tools Search this Thread
Search this Thread:

Advanced Search

 



Google
 

All times are GMT -6. The time now is 05:17 AM.


DV Info Net -- Real Names, Real People, Real Info!
1998-2017 The Digital Video Information Network