1/8" audio

omnikron

omnikron

Well-known member
Hey guys,

I've got a GH3 and I'm wanting to make a super-light setup that allows me to use the Rode Videomic pro AND a Sennheiser G2 unit.

For interviews, I currently use my Mix Pre and send line level signal through XLR to my Tascam DRMKII. Then from my Tascam, I have a Sescom line level to mic level cable that I run from the Tascam into my GH3 and it sounds perfect. In fact, it sounds good enough to me that I'd like to have multiple options for recording to the GH3 depending on the situation.

I'd like to bypass the Tascam and go directly to the GH3. I think I can do that but I just need to get a stereo female 1/8" coupler to go from my Hosa XLR to 1/8" cable so I can then put the Sescom cable into the line. http://www.fullcompass.com/product/448596.html

What I would LIKE to do that I don't know how is to bypass using that Hosa adapter completely (http://www.fullcompass.com/product/448596.html), because it's big & clunky and I want to have the lightest rig I can for the Rode Videomic Pro and Sennheiser G2. I'd like to just use the 1/8" out from each of those devices into a Y adapter that then plugs into the mic in on my GH3. I've done it successfully with the XLR to 1/8" cable and the levels were perfect.

But I have tried 2 of my 1/8" stereo Y adapters and they only work on one channel. It seems they are wired to go the other direction, taking a stereo signal and splitting it into 2 channels rather than taking 2 mono channels and putting them into a stereo 1/8" cable where one channel is on the left and one is on the right.

Does anyone know if there is such a cable?
 
Doesn't your MixPre have a "Tape Out" connector? You should be able to use a common 3.5mm Stereo to 3.5mm Stereo cable (Radio Shack has several models of different colors and lengths).

350-MixPre_LeftSide.jpg
 
It does, but it doesn't work with my Sescom cable for some reason... forgot to mention that. It works from the Tascam just fine.
 
Good idea... any idea on finding a 1/8" y-adapter for converting 2 mono channels into a stereo channel?
 
I've never seen a mono to stereo 3.5mm splitter/combiner. If you must have a small adaptor, you can get 3.5mm to two phono(RCA) sockets - and if you were prepared to chop off the 3.5mm plugs and swap them for phonos, that would work.
 
If you are using the "TAPE OUT" connector on your MixPre, then you do not need a Y-cable of any kind.
You need only a simple TRS 3.5mm to TRS 3.5mm cable wired straight-across 1-to-1.
 
Richard: Maybe I wasn't clear in my first post or you just missed it but I'm trying to set up multiple configurations. The mix pre is only one configuration. I don't want to use the mix pre for run & gun. Thanks to you, I figured out that I was using the tape return and not the tape out from my mix pre, so now that configuration works perfectly, although it could just be me but I think the line out of the mixpre is slightly hotter than the line out from the Tascam DR100mkII
 
" I think the line out of the mixpre is slightly hotter than the line out from the Tascam DR100mkII"
-- That's quite possible, most SD 'Tape out' connection are -14dB (nominal), don't know about the MixPre, the Tascam could be less or hotter. Depends on the input. You could look up the specs to see exactly.
This is typical for difference manufacturers. Nothing wrong with either way.
 
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Those cables will do the trick, but I thought the idea was to go direct, cutting out as much extra kit as you could - as even an XLR was deemed too big. The gain structure looks a little odd with the mix-pre. The G2 is going to have to be dropped down to match the mic input, and gain is then applied, to this and the Rode mic, then the record output will have to be dropped down again to match the camera mic input. I'm not familiar with the camera. Does it allow independent control to handle the radio and Rode?
 
Well the Rode and Sennheiser G2 both have 1/8" male outputs, adapting to RCA and then using the RCA y-adapter to 1/8" into the GH3 seems to be a much lighter solution than the XLR cables, and the distance is mere inches. Once I try it, I'll post my results.

The GH3 does not allow independent control of the audio channels, however this is not a problem as both the Sennheiser G2 and Rode Videomic both operated perfectly when I used the XLR cables. I use a Countryman B3 with the Sennheiser and the levels I'm getting were just in the sweet spot for dialogue. The Rode Videomic runs a little louder than ideal at the +20db level but it's fine for most ambient. It should be turned down to 0 for loud environments, or ideally, a 5-10db inline pad could be inserted between it and the camera.

The results are what matters. I'll have to do more field testing once I get those cables. Thanks for the idea of the RCA adapter.
 
I must be unclear on what you are trying to do. The Rode Videomic Pro and Sennheiser G2 can both send out a mic level signal. So why not send one into the left and one into the right channel? Finding or wiring such a cable is pretty easy.
 
That is exactly what I was trying to do. But you must have missed my post about how you cannot use an 1/8 stereo y-splitter cable to do that. Paul's suggestion of going from 1/8" to rca back to 1/8" worked
 
Okay, so I received the cables and did some informal testing with several mics.

Regarding the Sennheiser G2 wireless system with a Countryman B3 mic:

#1 Directly into the GH3 using the 1/8" to XLR adapter sounded identical to using the 1/8" to RCA to 1/8" adapter (I did test it at the same time as the Rode Videomic and it properly splits the L&R channels).

#2 Into the Tascam, and then from the Tascam into the GH3 using the Sescom able. Audio has less noise in the Tascam than in the GH3. The Tascam sounds more 'full' whereas the GH3 feels a bit tinny.


My conclusions as a whole after testing many different mics:


#1 - My Sennheiser G2 wireless system is noisier for my Countryman B3 lavelier than when I go directly hard-wired to XLR using the Sennheiser MZA900P to connect to my B3. The noise floor is noticeably louder, even when going through my SD Mix Pre. I heard no advantage going through the Mix Pre vs. the Tascam when using the wireless. (is this common for these wireless units when there is no interference?)

#2 - Any mic requiring phantom power sounds MUCH cleaner going through the Mix Pre and then recorded onto the Tascam. Sending the audio then from the Tascam or the Mixpre introduces noise as the GH3's noise floor is higher. If you have the time to properly record through the SD and record onto a Tascam, the noise floor much better than the noise floor of the GH3.

#3 - If I need to go light and I'm recording in an already noisy environment, going directly into the GH3 with the Sennheiser G2 and Rode Videomic Pro using either an XLR to 1/8" or the 1/8" to RCA to 1/8" adapter is sufficient to get good, undistorted sound. The only difference being that the noise floor is higher and the audio spectrum does not sound as full as it does when recording using the Tascam. I feel that the Tascam captures more of the bass, however to my untrained eye, looking on the multimeter in Sound Track Pro, I couldn't really visually see any difference
 
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I suspect the increased noise floor with the radio channel is simply bad gain structure - dropping down to mic level, then back up again in the camera - which has less than sonically perfect preamps (it doesn't pretend to have excellent audio specs). If you back the gain down on the camera and up it on the receiver, I bet the problem gets much better - BUT with ganged L&R controls, this is not practical as you will lose the other channel!
 
No, that's not the issue. It happens also from the Mix Pre directly into the Tascam, and it's with the Sennheiser received at +12db selected for AF Out. It obviously sounds slightly better when recorded into the Tascam but the gain is still much worse than when not using the radio.
 
If your running the G2 receiver's 'AF out' setting @ +12dB into a mic level input, you must have the transmitter's 'Sensitivity' set very low. That could account for the high noise floor. I frequently run the G2's AF out set to +12 into line level.
 
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