Dual DPA 4098 + Zaxcom TRX742 Car Rig

[Ze Frias]

I've been experimenting with the DPA 4098s for car mounting, and after some tinkering, I've made this dual 4098 mic setup going into the Zaxcom TRX742 wireless plug-on transmitter.

It's proven very useful for recording the driver and passenger simultaneously, and very flexible as I'm using the "stereo" cone on the TRX742, allowing me to transmit two discrete tracks within the same transmitting frequency, as well as record a two track MARF backup to the built-in MicroSD card.

The mics and transmitters are rigged using a stereo mount that I've made up with pieces I had around. I'm using a dinkum arm to grip it to the cup holder divider in between the driver and passenger seats in the photos below.

I'm already working on a different "upgraded" version of this that will use a heavy duty suction cup to attach the rig to the windshield, and with an actionable arm to keep it flush against the roof of the car. Then I can bend the gooseneck to the ideal mic'ing position.

 

[Matthias Richter]

looks good! You might wanna get a 90`antenna to keep it low profile.

 

How is the 742 playing with the DPA in close distance? Any RFI problems?

 

Just used my 742 with a CMC6MK41 in a car that got out of reception. That part was missing on the card?! It might have been a close Teradek transmitter on the camera that confused the 742 ... Have switched off the IFB function since then if I needed to rely on the card recording.

[Ze Frias]

Thanks! No RFI issues at all whatsoever. I'm very happy with this rig so far. Still experimenting with other ideas to improve on it. 

Regarding the missing card recording, did you have remote transport control active on the 742? I typically turn it off, and manually set the transmitter to record. Hasn't failed me yet.

Edited July 11, 2015 by Jose Frias

[Glen Deakin]

hows the run time using the stereo cone?  

[RadoStefanov]

Jose can you mount it somewhere else where it is not in the way of the driver?

[Ze Frias]

Jose can you mount it somewhere else where it is not in the way of the driver?

Yup, that's one of the things I'm trying to improve. As I mentioned in the OP, I'm modifying this to use a suction cup with an actionable arm instead of the Dinkum arm to mount it on the windshield and keep it flush against the roof to be completely out of the way.

[Ze Frias]

hows the run time using the stereo cone?  

Not 100% sure. I'll test it out and get back to you on that.

[Glen Deakin]

Not 100% sure. I'll test it out and get back to you on that.

 

Thanks.  Question though. Does the 742 provides 48V for both microphones?  Im curious to know how long the batteries last while using.  

Edited July 13, 2015 by Glen Deakin

[Matthias Richter]

Regarding the missing card recording, did you have remote transport control active on the 742? I typically turn it off, and manually set the transmitter to record. Hasn't failed me yet.

it´s been in loop record all the time. A parallel TRX900 had the recordings but with completely TC-offset. Everything before and after was ok on both transmitters.

[Matthias Richter]

 

Thanks.  Question though. Does the 742 provides 48V for both microphones?  96V total.  Im curious rot know how long the batteries last while using.  

96V?? It´s still 48V but draws more current than a single mic

[Ze Frias]

 

Thanks.  Question though. Does the 742 provides 48V for both microphones?  96V total.  Im curious to know how long the batteries last while using.  

I understand your question. It indeed powers both microphones simultaneously at the same phantom power level, but with a higher current draw. So battery life will likely be shorter.

Like I said, I'll have to test it out to see how long the batteries last, as I haven't tested it to its limit.

Edited July 11, 2015 by Jose Frias

[Glen Deakin]

Well say i wanted to use my MS setup MKH30/8040 can i do that with a 742?

[Ze Frias]

96V?? It´s still 48V but draws more current than a single mic

Just realized you beat me to the punch.

[Glen Deakin]

Correct not sure what i was thinking with the 96v thing.  

[Ze Frias]

Well say i wanted to use my MS setup MKH30/8040 can i do that with a 742?

Yes you can. You need only the proper Y-cable to end on the XLR5M.

Edited July 11, 2015 by Jose Frias

[Glen Deakin]

Well planning to use with my Pianissimo so cabling is not a problem.  Just wanted to confirm that it can do it before i go ordering a stereo cone.  

[Jack Norflus]

That's a great car rig - quick and easy to deploy. 

[Ze Frias]

Well planning to use with my Pianissimo so cabling is not a problem.  Just wanted to confirm that it can do it before i go ordering a stereo cone.  

It definitely can. I just couldn't tell you how long the battery life will be for sure.

[Glen Deakin]

Sweet thanks

 

 

[Solid Goldberger]

Jose,

Could you briefly compare the sound of the 4098's using the TRX742 vs TRXLA2s?  I'm wondering how much of a difference the 48v power makes sonically. 

E. 

[Ze Frias]

Jose,

Could you briefly compare the sound of the 4098's using the TRX742 vs TRXLA2s?  I'm wondering how much of a difference the 48v power makes sonically. 

E. 

Gladly, I still need to do some more tests and recordings before I can say for sure.

But theoretically, since these mics on spec require 5v, they would have lower sensitivity and a higher noise floor when being powered w/ TRXLA2s. In practice, from the very early tests I've been doing so far, this lower sensitivity / added noise floor has been negligible in comparison to the set-up described above, from what I can hear based on the program content I'm recording (reality). I imagine in narratives where you may go from whispers to screams, this may be more noticeable, but I couldn't tell you for sure, yet.

I'll report back once I've had these for a bit, but I think that even just with the TRXLA2s, with a good mic position, you can get great recordings despite the lower sensitivity and higher noise floor. For sure much better than you could with the Omnigoose or InstaStash IMO.

[Jason A]

Very timely post Jose! I have both mics and the 742 on the way. Was already brainstorming how to get a similar set up. Thanks for the info!

[Wandering Ear]

Nice rig Jose.  I've used similar center console rigs using schoeps with gvc's, having the gooseneck would be more flexible. 

I used these mics last year on a movie with my trx900la's and didn't notice any more noise than with a 742.  It could've had a higher noise floor,  but not enough for me to care. 

[John Blankenship]

When I've tried 5 volt DPAs with Zaxcom TRXs, I've not noticed any increase in noise floor unless it was digital RF related.

By all accounts thus far, these mics don't exhibit such tendencies.

[Jeff Wexler]

I echo what John, Jan and Jose have said regarding 5 v. DPAs and Zaxcom transmitters. I know the published spec for these mics is a supply voltage of 5 volts (which the Zaxcom transmitters do not provide) and I know as well how this could affect performance, but it seems to be almost a non-issue in real world usage. The noise floor and overall incredible dynamic range of the Zaxcom wireless may be a factor working in our favor, I don't know. In any case, for me (and evidently for those who have already had a lot more experience with these mics and Zaxcom), the 3 volt vs. 5 volt spec should not deter anyone from using these mics.