SL-2 RF issues...anyone else?

[thenannymoh]

I was pretty happy to get my SL-2 to go along with the 888.  But  I've noticed much more RF hits and hyper-sensitivity to my LT hop transmitter (which rests outside the bag) with my SRc receivers in the slots.  It triggers the yellow LED antenna load lights all the time, and creating audible hits at times.  Odd...since my other bag is TINY with a MixPre3, the same LT hop and the same SRc unit/s in close quarters with zero problems.  Same frequencies used.  B1 for both the hop tx and the SRc units.

 

Anyone else having issues like this with the SL-2?  

 

Thanks!

[Peter Mega]

Have a look at your antenna filter options in your SL2 menu in the 888. 
 

You will surely need to select the correct band. 

[Paul Katzman]

Lots of discussion on the Facebook group. Tldr, I think the filters are not steep enough, this seems to be an issue for lots of people. 

[rich]

i have started using my Audio Wireless DADM226-DT in my bag rig in place of the antenna distro on the SL2, and i feel a lot happier with how it is performing.

whislt i havent had opportunity to use it a great deal, i could at least see that if i keyed a walkie near to the antennas, the receivers wouldnt lose signal.

[thenannymoh]

1 hour ago, rich said:

i have started using my Audio Wireless DADM226-DT in my bag rig in place of the antenna distro on the SL2, and i feel a lot happier with how it is performing.

whislt i havent had opportunity to use it a great deal, i could at least see that if i keyed a walkie near to the antennas, the receivers wouldnt lose signal.

 

I have that same distro on my cart...is your SL2 still attached, but you are running antenna to the DADM from the SL2 (front or side outs)?

[rich]

I’m not using any of the RF bits of the SL2. 

[IronFilm]

Has Sound Devices responded at all to these reports of issues? (perhaps released a minorly tweaked hardware revision with steeper filters?)

[RScottATL]

This is a problem with you causing your SRc to become overloaded with excessive energy from the wideband inputs.

Wideband recievers by design rarely include very effective filtering, and your RF inputs need to account for that, a fact wideband manufacturers rarely educate their customers about, instead focusing on the obvious benefit of flexible tuning.

The whip antennas you have been using with the units act as a bandpass with their inherent frequency response.

So the door is open for interference with your SRc's, what has to happen then, is that the units will perform just fine under most circumstances, and when enough RF garbage is allowed to come into your SRc's, your threshold of performance shrinks, and at some point you can't perform basic operation with tolerable performance until you deal with the problems your receivers are struggling with.

Two places this happens frequently with users of distribution equipment is A. letting stronger RF levels into the system using wideband antennas with wider passbands and antenna gain  and  B. Introducing wideband active stages to the system without any additional consideration. These two things are tag-teaming your SRc and your SRc is losing the fight.

Intermodulation distortion products are included in the amplifiers output when ANY two frequencies mix in an amplifier system at any level, and this happens For EVERY frequency against every other frequency, from one end of the spectrum to the other. The LEVEL of these products can range from very very low, to very very high. 3rd order IMD products, which are the nasty ones, rise exponentially with rising amplitude of the input signal.

There are two places this is manifests itself -- higher noise floor across the entire passband of the system, caused by the summation of all the cumulative intermodulation distortion noise of the entire passband of the system -- and secondly, from overload happening when very strong RF inputs within your passband create excessive IMD products within your system. The first problem is dealt with by filtering an input that is too wide and forcing your distribution amplifier to output distortion from unnecessary input energy. The second problem can be solved by level control (lower output, wider spacing from your TX antenna, attenuators to your RX inputs) or else by insuring your filters control the levels for you by designing a system that does not include the transmit frequency in the passband for your RF amplifier stage or your receiver inputs.

The short term solution is get the SRc's out of the distribution device, or get rid of the TX on the same band, until you understand and can address the problems with your RF setup. You've not set the system up correctly for your application, and have added equipment in the way of your signal that buys you worse performance than the $10 whips you started with. (part of the blame should fall on manufacturers who sell these systems with little to no education on proper setup).

To make the distribution amplifier and receivers you have produce any positive results for you or hell, just to perform on par, make the TX energy exist OUTSIDE the passband of your distribution amplifier -- filtering is required after the antennas and before the distribution amplifier.

 

[Michael Capulli]

What freq is your LT and your SRCs tuned to? It would be better to have an A1 LT transmitting next to your receivers.