Shure UC wireless mic's to much gain (mod) - Page 1
Forum section: electronics / beginners

author: Remy007
author_rank: Newbie
timestamp: April 13, 2016, 08:34:46 am
content: I hope you guys may help me with a problem.I have 2 wireless microphones and 2 receivers both have the same problem.First I think there is nothing wrong with the devices, just a problem for my kind off use.The gain on the transmitter is all the way down, but still the mic is to loud coming into the receiver.I mean, the signal is clipping on the receiver when I shout into it. (I hear then a distortion)So, or the signal is receiving to loud ( I cannot change this on the receiver)Or the signal is transmitting to loud, I think this is the problem.Its possible to change the mic heads to another type like Beta58a, Beta87a, SM58, ...so there are some difference in gain is think.I have the Beta58a heads.On the receiver I have leds indicating the signal is to HOT.So want to make the audio about 6dB weaker then SHURE intended to be.(the gain trimmer on the transmitter is all the way down, and still a little to load)I tried something but it is not working.I replaced the trimmer for audio gain (100K ohm) with a 250k ohm trimmer, but the result is axactly the same!Then with 2 100K resistors (200k total) still the same output volume.So I think the audio gain is controlled by a chip and not simply routed true the audio gain trimmer.The trimmer controls the chip.I am thinking to put a resistor in de mic head itself between the positive wire (maybe 40 ohm and see what happens)So the incoming signal will be weaker before its going into the transmitter (or is this not a good idea?)The head and transmitter are different parts. You can put other heads on there for different sound carasteristics.Is there another way to lower the output volume for the transmitter you think ?Shure UC2 (transmitter) service manual:http://bmamps.com/Schematics/Microphones/Shure_UC2_Wireless_Transmitter_Service_Manual.pdfNormal manual UC2 transmitter:http://cdn.shure.com/user_guide/upload/2006/UC_Wireless_User_Guide.pdfThere are some pictures attached.Thanks!From Belgium.

author: lincoln
author_rank: Regular Contributor
timestamp: April 14, 2016, 06:43:32 am
content: Hold on their chef, did you try poting the level down on the receiver?

author: Richard Crowley
author_rank: Super Contributor
timestamp: April 14, 2016, 07:12:10 am
content: Quote from: Remy007 on April 13, 2016, 08:34:46 amSo that means the attenuator is set for "-20dB", can you confirm that?AND you have the "Transmitter Gain Level" control all the way DOWN (counter-clockwise).QuoteYes that is exactly as we would expect. A potentiometer selects a RATIO of the input signal. The absolute resistance of the pot from end-to-end will make essentially no difference in the adjustment levels.If you put a resistor between the "high side" of the adjustment pot and the incoming signal, that would give you better range of low-level adjustment on the pot. But it seems very odd that even with 20dB of attenuation AND the pot all the way down, the signal is still too hot.And, as @lincoln observes, the level adjustment at the receiver also plays it's part of the gain-structure.

author: Remy007
author_rank: Newbie
timestamp: April 16, 2016, 08:58:31 pm
content: Quote from: lincoln on April 14, 2016, 06:43:32 amThe gain on the receiver is only for output signal to XLR or JACK.Has nothing to do with the signal coming in from the mic.

author: Remy007
author_rank: Newbie
timestamp: April 16, 2016, 09:05:16 pm
content: There is no 20dB of attenuation button on the mic! (its the UC2 not the UC1 belt pack)Only a gain potmeter, all the way down.I have 2 mics and 2 receivers both to hot coming into the receiver.The problem is the people using it!They shout into the mic from to close and then the signal is to hot.I hear it, its distorted.The VU meter on the receiver is for signal coming in, when it hits red, I hear it instant.I also have different Sennheiser wireless mics (Like ew500 g3)And they are at -18db for basic operation, sometimes even at -25db for some singers.from the moment the Shure UC goes into clipping i hear it instantly!I have made a film with the problem:https://youtu.be/MvP6-XMxpO0