Jump to content

Mixpre-10t - Talkback mic


roubi

Recommended Posts

Hi,

 

The SD MixPre-10t is a great machine, but I missed a mic to talk with the boomop.

 

As the inputs 9-10 can provide pip, I built a small talkback box.

I used one of the stock microphone I got with sony uwp d-11 (I am using Sanken cos-11), a switch I got from an old cheap solder iron and a 3d printer. It is pluged on inupt 9.

It works well, I haven't tried it in a live situation yet. It is then sent on output 2 with the boom to the boomop.

 

On the downside :

- you can't send input 9 or 10 in prefader mode (as there's no fader for it), so I have to route it on the right channel. It means I can't send anything else on the right channel and my mix has to be on the left channel only (booms + lavs ; usually, I send booms on left, and lavs on right). It is not a big issue as post will be done with isos most probably but still, I would love to have the possibility to send inputs 9 and 10 prefade.

-there's a "pop" when pressing and releasing the switch. I guess a capacitor could help but my electronic knowledge is not good enough to work on this without the fear to break something in the mixpre.

 

Hoping it could inspire some people...

 

 

 

 

IMG_20190208_094346.jpg

IMG_20190208_094431.jpg

IMG_20190208_101340.jpg

Link to comment
Share on other sites

24 minutes ago, daniel said:

+1

How are you finding the USB controller for mixing of dialogue?

 

I just got it so I haven't tested it yet in a shoot situation but I am pretty sure it is not that great for mixing : the faders are very small and the 0 position is like at 1/3 from the top. My next shoot will be more mixing for director and reference sound. The post will be using isos ; so not a big problem for me at the moment.

Other than the size of the faders, the others controls are great. It is responsive, stable, plug and play.

It's also very light and small.

Link to comment
Share on other sites

On 2/8/2019 at 5:39 AM, roubi said:

-there's a "pop" when pressing and releasing the switch. I guess a capacitor could help but my electronic knowledge is not good enough to work on this without the fear to break something in the mixpre.

 

Cool!

 

I'm assuming that is a powered electret mic capsule, so the switch is connecting and disconnecting power from the MixPre-10t, and there's not a simple way to get power to the mic AND disconnect audio.  You could change to a dynamic element. You could battery power the existing within the box, isolate the audio line to the MixPre-10t with a series capacitor, and have the on/off switch after the capacitor on the way to the MixPre-10t.

 

Link to comment
Share on other sites

  • 2 weeks later...
On 2/9/2019 at 8:19 PM, EmRR said:

 

Cool!

 

I'm assuming that is a powered electret mic capsule, so the switch is connecting and disconnecting power from the MixPre-10t, and there's not a simple way to get power to the mic AND disconnect audio.  You could change to a dynamic element. You could battery power the existing within the box, isolate the audio line to the MixPre-10t with a series capacitor, and have the on/off switch after the capacitor on the way to the MixPre-10t.

 

 

Hi,

 

Sorry for the late answer, I missed the notification. Indeed, it is a powered mic capsule ; it is the stock mic I got with the Sony UWP-D11 pack.

I don't want to care about another battery to change/charge so I don't want to a battery powered box. 

A dynamic mic would be a good option, but I like to use what I already have : those several stock UWP mics.

So that leaves the capacitor thing ; I just do not know enough about electronics to calculate this. If you know a bit about it, I'm all ears...

Thanks.

Link to comment
Share on other sites

6 hours ago, Vincent R. said:

@roubi Often it's done by wiring a LED in combination with the switch; if the switch is off, a red LED turns on, powered by the bias power, if it's off, the mic turns on. The load will stay constant then, so the pop will not occur. 

 

That sounds like a good idea. But it would need a switch with 3 positions, wouldn't it?

Link to comment
Share on other sites

  • 4 years later...

I know I'm necro-bumping this thread, but I think I have a few ideas to share on this topic 🙂

 

Below you'll find a simple schematic for a passive, popless mic mute circuit. It's a very simple design needing only a resistor, a capacitor and a switch. This circuit is a mute switch, but can be transformed easily into a push-to-talk circuit by swapping the switch with an ON-(OFF) pushbutton. I replaced the 100uF C1 capacitor with a 470uF capacitor which gives better attenuation. This circuit has already been mentioned here, with a nice comment from Larry Fisher:

 

As for using an Aux Input of the Mixpre-10T to provide plug-in power and a preamp for an external talkback electret mic, I discovered that there's actually no need to assign the Aux Input to a track (track 9 or 10) of the Mixpre to use it as a talkback mic. When the Aux Input is configured as a Mic level input, it can be assigned to any L, R, X1 or X2 output and combined with the prefader boom ISO track to send a feed to the boom operator. With this simple hack, there's no gain setting available, but the default Aux Mic Input gain seems to be just about right for this purpose. And you won't lose one of your mix tracks.

 

Another, perhaps more complex but also more powerful setup would be to use a cheap and tiny electret mic preamp such as this one https://www.adafruit.com/product/1063 to power and amplify the talkback mic in order to feed it directly at line level into the Mixpre Aux Input configured as a camera return, which provides a gain setting. And there's an adjustable gain trim pot on the electret mic preamp as well. Or mix the line level talkback signal directly into the boom monitoring transmitter through a simple passive mixer circuit needing only two resistors. Of course, the talkback box would not be passive anymore, as the little electret mic preamp wants 2.4-5.5V which could be provided by three AA batteries.

electret mute switch.png

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...