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Title: Shure wireless distortion
Post by: Nathan Vanderslice on April 05, 2015, 10:35:07 pm
Okay, I'm using one of the blx series wireless mics and am having problems with distortion and clipping at the mic (singer tends to yell into mic). I'm also getting a "clipping indicator" on the unit. This is definitely where the problem is. I don't know if I can get the performer to change their ways, but I'm wondering if there's another way to solve this problem. There is a gain control on the mic, but will that work? Is the gain for the mic element output to preamp, gain sent to receiver, or what?
Title: Re: Shure wireless distortion
Post by: Jordan Wolf on April 05, 2015, 11:14:09 pm
Nathan, I haven't had a chance to look at that model's specs, but many units have a pad that can be engaged to pad down the signal coming from their element before it reaches the gain stages in the belt pack circuitry. It's typically around -20dB.


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Title: Re: Shure wireless distortion
Post by: Lee Buckalew on April 06, 2015, 05:21:14 am
Okay, I'm using one of the blx series wireless mics and am having problems with distortion and clipping at the mic (singer tends to yell into mic). I'm also getting a "clipping indicator" on the unit. This is definitely where the problem is. I don't know if I can get the performer to change their ways, but I'm wondering if there's another way to solve this problem. There is a gain control on the mic, but will that work? Is the gain for the mic element output to preamp, gain sent to receiver, or what?

Look here on page 5, Adjusting Gain.  Set to -10.  If it still clips and/or distorts then you have the wrong tool for the job.  -10 will almost never take care of yelling directly into the mic in my experience.

http://cdn.shure.com/user_guide/upload/1983/blx-wireless-user-guide-english.pdf

Lee
Title: Re: Shure wireless distortion
Post by: Nathan Vanderslice on April 06, 2015, 05:55:11 am
Nathan, I haven't had a chance to look at that model's specs, but many units have a pad that can be engaged to pad down the signal coming from their element before it reaches the gain stages in the belt pack circuitry. It's typically around -20dB.


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Sorry, I should have specified that it is a handheld mic.
Title: Re: Shure wireless distortion
Post by: Keith Broughton on April 06, 2015, 06:15:44 am
Sorry, I should have specified that it is a handheld mic.
There is also a gain adjustment for the hand held.
Title: Re: Shure wireless distortion
Post by: Lee Buckalew on April 06, 2015, 07:23:44 am
Sorry, I should have specified that it is a handheld mic.

The link, in my previous post, tells you how to adjust the gain on the handheld.  Doubtful it will be enough but it's all that you have to work with on the BLX.

Lee
Title: Re: Shure wireless distortion
Post by: Brian Jojade on April 06, 2015, 11:47:25 am
If you can't get the performer to change their ways, then you either have to change equipment or the performer.

The -10 will help a bit, but if you're yelling into the mic, it's not going to be enough.  It'll still clip.
Title: Re: Shure wireless distortion
Post by: Luke Geis on April 06, 2015, 03:28:22 pm
The lower end mics are just not worth the money. Sennheiser G3 series is about as good of an affordable mic as you can get. The Shure entry level mics are the worst offenders for not having enough adjustment to eliminate clipping. The lowest end ones usually only have a -10db pad, while even the higher end models have an adjuster that doesn't always get low enough. If the singer cannot recognize when the mic is clipping your going to have your hands full. They need to back off a bit to keep the level optimal.
Title: Re: Shure wireless distortion
Post by: Nathan Vanderslice on April 07, 2015, 12:01:43 am
What about using an AKG 535 with the 14 dB pad?
Title: Re: Shure wireless distortion
Post by: Tim McCulloch on April 07, 2015, 12:47:02 am
What about using an AKG 535 with the 14 dB pad?

I love the C535 but it's not a go-to choice for screamers or shouters.  I had one gospel tenor easily overload a 535 with the pad engaged...
Title: Re: Shure wireless distortion
Post by: Nathan Vanderslice on April 07, 2015, 10:17:41 am
I love the C535 but it's not a go-to choice for screamers or shouters.  I had one gospel tenor easily overload a 535 with the pad engaged...

Thanks. Would there be any difference between the wireless sm58 and the wired one in terms of distortion?
Title: Re: Shure wireless distortion
Post by: Mac Kerr on April 07, 2015, 11:21:59 am
Thanks. Would there be any difference between the wireless sm58 and the wired one in terms of distortion?

Yes. The wired one doesn't have a transmitter and receiver between the mic and the mic input.

Mac
Title: Re: Shure wireless distortion
Post by: Lee Buckalew on April 07, 2015, 11:45:12 am
Thanks. Would there be any difference between the wireless sm58 and the wired one in terms of distortion?

Nathan,
You are not seeing distortion caused my the mic capsule of a dynamic mic clipping unless it is from plosives or "P-Pops".  The SM58 at 1kHz can handle around 160dB/SPL before diaphragm excursion causes a problem.  The level required to create this movement would vary with frequency but should be far higher than a vocalist can produce.

You are seeing clipping of the microphone electronics feeding into the RF section of the transmitter. 
This would not be present for a hard wired mic (unless you turn up your mic pre too far).

Lee
Title: Re: Shure wireless distortion
Post by: Kevin Maxwell on April 07, 2015, 11:46:47 am
Thanks. Would there be any difference between the wireless sm58 and the wired one in terms of distortion?

I had a gospel singer once distort a hardwired SM58, not the preamp on the board but the diaphragm of the mic itself. I thought that there was some other problem but then I was told that that is how she sounded. Actually she may have really been distorting her vocal cords.   :o
Title: Re: Shure wireless distortion
Post by: Luke Geis on April 07, 2015, 06:18:16 pm
i think that with many of the lower end RF stuff the biggest problems come from lack of bandwidth. There is only so much information that can get from point A to point B. Thus compression and companding are employed. The lower end mics have less bandwidth therefore higher amounts of compression and companding are employed. The issue could be one of two things when you actually hear distorted sound.

1. The circuit in the mic and or the receiver are actually clipping from a bad gain structure setup. This is probably most common and is the fault of the user for not addressing it.

2. The mic is getting a really hot signal that it must compress highly in order to squeeze the info within the allowed bandwidth. The resultant compression and subsequent companding are heard as crunching and distortion. The peaks of the audio that are highly compressed are not always companded ( Basically expanded ) as well as it went in and the wave form can show signs of distortion. 

Another nasty side effect that some systems do is eliminate the audio spectrum that is deemed worthless. The mic and or receiver will neglect info above and below a certain sonic threshold. Basically lows and highs are cut out of the transmission. This is another reason that RF doesn't always sound like their wired counterparts. The advent of digital RF that is now becoming standard is great. The info is not compressed or companded and is sent with full audio spectrum bandwidth. The only trade off of is a minute amount of latency. This new digital technology brings the RF mics closer if not exactly like their wired counterparts.

If your getting distortion and you have the pad engaged there is only 2 ways to eliminate it. Either a higher quality ( or digital ) RF system, or going back to a wired mic.
Title: Re: Shure wireless distortion
Post by: Nathan Vanderslice on April 07, 2015, 11:59:50 pm
Thank you to all for some great advice and for explaining it all so well. Now to another question. A couple of weeks ago, I was experimenting with different mics for a speaker cab, and with the AKG C3000, I was a bit taken aback as it sounded both a little distorted, and had kind of a bassy ?sp? muffle. Amp was down to almost the lowest setting, and the mic was ~ 2-3" away from the cab. At the same time, we had tried the same mic for vocal and found it actually quite nice. It had a nice presence in the middle to middle high range for a really clear and easy to understand speech. Any thoughts?
Title: Re: Shure wireless distortion
Post by: Tim McCulloch on April 08, 2015, 02:45:02 am
Thank you to all for some great advice and for explaining it all so well. Now to another question. A couple of weeks ago, I was experimenting with different mics for a speaker cab, and with the AKG C3000, I was a bit taken aback as it sounded both a little distorted, and had kind of a bassy ?sp? muffle. Amp was down to almost the lowest setting, and the mic was ~ 2-3" away from the cab. At the same time, we had tried the same mic for vocal and found it actually quite nice. It had a nice presence in the middle to middle high range for a really clear and easy to understand speech. Any thoughts?

The address-side of the mic was facing away from the guitar speaker.  It was backwards.
Title: Re: Shure wireless distortion
Post by: Lee Buckalew on April 08, 2015, 06:54:58 am
i think that with many of the lower end RF stuff the biggest problems come from lack of bandwidth. There is only so much information that can get from point A to point B. Thus compression and companding are employed. The lower end mics have less bandwidth therefore higher amounts of compression and companding are employed. The issue could be one of two things when you actually hear distorted sound.

1. The circuit in the mic and or the receiver are actually clipping from a bad gain structure setup. This is probably most common and is the fault of the user for not addressing it.

2. The mic is getting a really hot signal that it must compress highly in order to squeeze the info within the allowed bandwidth. The resultant compression and subsequent companding are heard as crunching and distortion. The peaks of the audio that are highly compressed are not always companded ( Basically expanded ) as well as it went in and the wave form can show signs of distortion. 

Another nasty side effect that some systems do is eliminate the audio spectrum that is deemed worthless. The mic and or receiver will neglect info above and below a certain sonic threshold. Basically lows and highs are cut out of the transmission. This is another reason that RF doesn't always sound like their wired counterparts. The advent of digital RF that is now becoming standard is great. The info is not compressed or companded and is sent with full audio spectrum bandwidth. The only trade off of is a minute amount of latency. This new digital technology brings the RF mics closer if not exactly like their wired counterparts.

If your getting distortion and you have the pad engaged there is only 2 ways to eliminate it. Either a higher quality ( or digital ) RF system, or going back to a wired mic.


To make a few corrections. 

Companding is a contraction of compressing and expanding.  It is used for noise reduction and to fit a wider dynamic range signal into a smaller dynamic range signal carrier.  It uses a specific fixed compression (not variable based on available signal level) at the transmitter with a corresponding fixed inverse expansion at the receiver.  See http://en.m.wikipedia.org/wiki/Companding
None of the analogue wireless that I am aware of employ a variable compressor.  Some companding circuits do sound better than others.
Not all digital wireless are companding free.  In fact there are only a couple out there that are recommended for use in measurement for this very reason. 

Analogue systems do not "eliminate the audio spectrum that is considered worthless".  That is what many digital audio codecs do.  Analogue systems may have fixed (not variable) limits on their frequency response that are almost always more limited than their digital counterparts.

Digital RF MICS take much more bandwidth per channel to create the same fidelity as their analogue counterparts.  This is one of their drawbacks currently.  Within a given price range there are some digital options now that are far better sonically than their analogue counterparts.  Shure ULX-D is one.  They are even sonically better than Shure UHF-R analogue but not Sennheiser 2000 or 3000 series analogue.  I would say they are sonically equal to or better than Shure Axient although Axient provides many other solutions to reception issues.  Sennheiser 9000 series digital sounds better than all of these.  I have not had a chance to use the digital offerings from Lectrosonics but their systems enjoy a very deserved reputation for high quality both in ruggedness and in audio signal fidelity.  Line 6 falls short in the professional audio world both in sonic quality and in channel count/density.

Lee
Title: Re: Shure wireless distortion
Post by: David Sturzenbecher on April 08, 2015, 08:03:03 am


To make a few corrections. 

Within a given price range there are some digital options now that are far better sonically than their analogue counterparts.  Shure ULX-D is one.  They are even sonically better than Shure UHF-R analogue but not Sennheiser 2000 or 3000 series analogue.  I would say they are sonically equal to or better than Shure Axient although Axient provides many other solutions to reception issues.  .

Lee

Lee,
The Shure UHF-R and the Axient have the exact same RF radios on board. So they should, and in my experience,  sound the same.


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Title: Re: Shure wireless distortion
Post by: Lee Buckalew on April 08, 2015, 08:44:20 am
Lee,
The Shure UHF-R and the Axient have the exact same RF radios on board. So they should, and in my experience,  sound the same.


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Yep, but ULX-D sounds better.  It has some slight shortcomings in RF reception compared to UHF-R and then there is Axient.  Amazing capability in the RF realm, slightly decreased sonic quality compared to ULX-D.

Lee
Title: Re: Shure wireless distortion
Post by: Nathan Vanderslice on April 08, 2015, 11:48:16 pm
The address-side of the mic was facing away from the guitar speaker.  It was backwards.

Thanks! Tim, perhaps you or someone else can clarify something for me on this mic. It is labeled as a "C3000" but is not black, it is the sort of gold/copper color, but it does have all 3 switches - pad, roll off, and cardioid/ hypercardioid. I also have the 3000 b which does not have the dual element.
Title: Re: Shure wireless distortion
Post by: Luke Geis on April 11, 2015, 01:23:19 pm
This is a test that shows basically what I was saying. You will notice that even a decent mid level Shure will have reduced total bandwidth and is not as well performing as one would imagine in comparison to other rf mics. This test was done by another member on this forum. Not my test results.       http://forums.prosoundweb.com/index.php/topic,1373.msg16536.html#msg16536