LuisT Posted December 25, 2021 Report Share Posted December 25, 2021 Hello Everybody, i did recently some range tests with a Lectrosonics SSM and an audio LTD A10 with 2 DPA 6060. I appeared after i put the files in Pro Tools that the 2 channels' phase are completely reversed. I swapped both mics and i have still the same result. The SRC and the A10 Rx phases are all positives. SSM compatibility mode is set to DPA. Am i missing something here? I never had to invert phase on similar mics in the past with different transmitters. (Also, same position for the 2 mics of course) Thanks Quote Link to comment Share on other sites More sharing options...
Jim Rillie Posted December 27, 2021 Report Share Posted December 27, 2021 I’m pretty sure with Lectro and COS11 the phase should be reversed. I believe the SSM in COS11 setting is phase reversed. I did it manually with SM transmitters and 411A receivers, usually at the receiver output. Hopefully someone from Lectro can clarify this. Quote Link to comment Share on other sites More sharing options...
LuisT Posted December 27, 2021 Author Report Share Posted December 27, 2021 Hey Jim, thanks for you input but i am not using Sanken Cos 11. Only DPA 6060 on each Tx'. Quote Link to comment Share on other sites More sharing options...
Jim Rillie Posted December 27, 2021 Report Share Posted December 27, 2021 That’s why I am hoping someone from Lectrosonics can clarify. May be the same situation. Quote Link to comment Share on other sites More sharing options...
karlw Posted December 27, 2021 Report Share Posted December 27, 2021 LuisT, what version of firmware is running in your SSMs? If it is v.1.02 or earlier, we corrected that in v.1.03 and all subsequent versions. Quote Link to comment Share on other sites More sharing options...
LuisT Posted December 27, 2021 Author Report Share Posted December 27, 2021 Hey Karl, my ssm's are running 1.08 and into "In DPA" mode. Could it come out of the A10 as well? Someone from Sound Devices? @Paul Isaacsmaybe ? Basically my problem is that the SSM and the A10 Tx are phase reversed with the same mic and same polarity on the Receiver end. I never encountered this before and i try to understand it. Quote Link to comment Share on other sites More sharing options...
rich Posted December 27, 2021 Report Share Posted December 27, 2021 assuming that have you compensated for the different latencies of the two systems (2ms for A10, 3.6ms for lectro), it could be that having the SSM in DPA mode has swapped the phase, but because there isnt a DPA mode for the A10, you'll need to change the output phase in the A10 menu, or at your recorder Quote Link to comment Share on other sites More sharing options...
LuisT Posted December 27, 2021 Author Report Share Posted December 27, 2021 Hey rich, thanks for your input. Does not look like 1.6ms delay beetween the 2 systems but like you say the SSM DPA mode vs the A10 with no mode. But what is still weird is that i shoot many times with A10 from rentals and never had this issue. Quote Link to comment Share on other sites More sharing options...
karlw Posted December 28, 2021 Report Share Posted December 28, 2021 On 12/27/2021 at 11:53 AM, rich said: assuming that have you compensated for the different latencies of the two systems (2ms for A10, 3.6ms for lectro), it could be that having the SSM in DPA mode has swapped the phase, but because there isnt a DPA mode for the A10, you'll need to change the output phase in the A10 menu, or at your recorder The end-to-end latency with the SSM and any 3rd-generation Hybrid receiver (SRc, Venue 2) is about 2.9 ms. Your figure for the A10 is correct, thus the difference between the two should be about 0.9 ms. There are several ways to adjust for the polarity mismatch - first, as you suggest, the output polarity in the A10 receiver can be switched to reverse. This can also be done in the Lectrosonics receiver. Also, instead of "DPA" input setup in the SSM, use a custom setup with the following values: Bias 4, Reistance Lo, Polarity pos (normally it is "neg" in the standard "DPA" setting). 23 hours ago, LuisT said: Hey rich, thanks for your input. Does not look like 1.6ms delay beetween the 2 systems but like you say the SSM DPA mode vs the A10 with no mode. But what is still weird is that i shoot many times with A10 from rentals and never had this issue. It may be that either the A10 system or the Lectrosonics system reverses polarity in an absolute sense. But if you ever only use one of the systems, you would never notice. It's not something you can typically hear on its own. If the two systems are used for different things, i.e. lav and boom, you might not notice it then, either, since the boom mic is usually a couple of feet away from the voice while the lav is a few inches - the natural delay difference means that you wouldn't necessarily hear a phase cancellation from different signal polarity. But, you might be able to see it in the waveforms. Quote Link to comment Share on other sites More sharing options...
karlw Posted December 28, 2021 Report Share Posted December 28, 2021 Update: we dug through the archives from a few years back and found the background info on why we "corrected" the polarity of the DPA input setup for the SSM. We found that the original version reversed absolute polarity. With firmware v1.03 this was corrected so that a positive sound pressure at the mic capsule results in a positive voltage on pin 2 of the receiver output. It may be that the A10 system then is "reversed" in this regard. Quote Link to comment Share on other sites More sharing options...
LuisT Posted December 28, 2021 Author Report Share Posted December 28, 2021 Hey Karl ! Thanks for all this info. Will try the custom setup with Bias 4, Reistance Lo, Polarity pos Quote Link to comment Share on other sites More sharing options...
rich Posted December 28, 2021 Report Share Posted December 28, 2021 2 hours ago, karlw said: The end-to-end latency with the SSM and any 3rd-generation Hybrid receiver (SRc, Venue 2) is about 2.9 ms. Your figure for the A10 is correct, thus the difference between the two should be about 0.9 ms. There are several ways to adjust for the polarity mismatch - first, as you suggest, the output polarity in the A10 receiver can be switched to reverse. This can also be done in the Lectrosonics receiver. Also, instead of "DPA" input setup in the SSM, use a custom setup with the following values: Bias 4, Reistance Lo, Polarity pos (normally it is "neg" in the standard "DPA" setting). It may be that either the A10 system or the Lectrosonics system reverses polarity in an absolute sense. But if you ever only use one of the systems, you would never notice. It's not something you can typically hear on its own. If the two systems are used for different things, i.e. lav and boom, you might not notice it then, either, since the boom mic is usually a couple of feet away from the voice while the lav is a few inches - the natural delay difference means that you wouldn't necessarily hear a phase cancellation from different signal polarity. But, you might be able to see it in the waveforms. thanks for the info Karl. it had been a while since i had checked the specs on the latency of the Lectro systems. and i was either gong from memory from a very old figure, or (which is very 2021) made up a likely sounding number and used that without actually doing any double checking. Quote Link to comment Share on other sites More sharing options...
LuisT Posted December 30, 2021 Author Report Share Posted December 30, 2021 Hello, so from my tests, indeed what seems to solve it is to set the custom IN into the SSM with Bias 4V, Lo res and Phase Pos. The A10 does not have an input adaptation so the phase is positive by default. You can clearly see in Pro tools also the Latency beetween the A10 Rx and the Src. Quote Link to comment Share on other sites More sharing options...
Dejan Ceko Posted March 9, 2022 Report Share Posted March 9, 2022 On 12/28/2021 at 9:58 PM, karlw said: Also, instead of "DPA" input setup in the SSM, use a custom setup with the following values: Bias 4, Reistance Lo, Polarity pos (normally it is "neg" in the standard "DPA" setting). Hi Karl, Bias 4 is maybe to low...or I am missing something..? "The bias voltage available in most transmitters is in the range of 5-7 volts. However, a few brands provide only 2-4 volts. DPA miniature microphones (lavaliers, headsets and instrument mics) need 5-10 volts to work correctly. One exception, however, is the low voltage version DPA 4063 which works down to 3 volts." - https://www.dpamicrophones.com/mic-university/how-to-properly-attach-a-dpa-microphone-to-a-wireless-transmitter Quote Link to comment Share on other sites More sharing options...
karlw Posted March 9, 2022 Report Share Posted March 9, 2022 Dejan, bias of 4v works just fine with the DPA lav mics and 4099s, etc. In fact, I'm doing a setup right now with our SSM and some 4099s, and they sound great together. I do set the load impedance to "0" instead of low, though, for more sensitivity with this particular mic. That is always an option. Quote Link to comment Share on other sites More sharing options...
Dejan Ceko Posted March 10, 2022 Report Share Posted March 10, 2022 15 hours ago, karlw said: I do set the load impedance to "0" instead of low, though, for more sensitivity with this particular mic. That is always an option. I will try the same with 6061 for those "from a whisper to a scream moments"...Thanks. Quote Link to comment Share on other sites More sharing options...
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