People have been talking about this on the "Obnoxious Tail End Distortion" thread, however, this seems to be a very popular and growing concern that is different than the tail-end distortion. Just to quickly bring everyone up to speed, it is the following sound that user "polishbroadcast" posted on the other thread:

http://snd.sc/iSNmTr

EDIT: Here is another recording that I made (explained later in the thread)
http://soundcloud.com/user4316001/musta ... range-fizz


Forums all over the internet are posting about this sound, calling it:

Sitar-Like
Phaser Sound
Bad MP3 sound
Strange Fizz
Etc.

There are even some reviews on big online retailers starting to pop up.

Here is my research:

The sound is called "Digital Aliasing." Some think it is a firmware issure, some thing it's a power issue. Fender is going to have to be the one to tell us. I was convinced to send mine back until I heard that many people have and gotten the same problem. I went to my local music store (I bought mine online) and found that the demo model there had the same problem. Funny enough, the guy working at the store said he couldn't hear it, although he has been playing clubs for 40 years.

Here is everything that I have tried:

Updating Firmware
Attaching different speaker (very broken-in speaker)
Changing advanced amp settings in fuse
Tried mustang I and II amps (Both did not have the problem, from what I hear, IV and V don't either)

It sounds like there are a lot of these amps out there with many people complaining about this noise. It makes it embarrassing to bring to rehearsals, unbearable to practice with (if using clean tones), and impossible to practice with. All three things I bought this amp for and I am sure that many other people did also.

I really hope fender gets on this and fixes this problem. Please post anything else that you have found regarding this noise. I think this amp is amazing, I am a professional guitarist, and if fixed, this amp is going to be just simply amazing. I held on to it fender, I have trust it you.

Great post. Thanks for clarifying. It just started to be clear that the issues were different, and the aliasing was a new beast. Glad you started this thread.

It seemed to me with the aliasing problem on the III, it only happens on the speaker output for most people. Can anyone confirm or deny? I don't hear it on headphones and haven't tested the USB.

My mustang III manufacture date is 11/2010

I have the same issues. I wrote about them in the Obnoxious Tail End Distortion thread.

I do not have this issue when listening via head phones. Using the speaker they are on every model and make the amp unplayable.

I've sent an email to fender support earlier in the week, and a PM this morning to Loren pointing out the recent posts in the Obnoxious Tail End distortion thread plus my own tests and mentioned that there were a number of people waiting to hear an official response from Fender.

I'll be returning the amp soon if Fender remains silent. I really hope I don't have to and there is a fix available.

I can confirm that there is no "Strange Fizz Sound" with headphones. Also using studio-quality AKG K240 headphones too. Even when turned all the way up. I also notice the the phasing of the sound changes with the turn of the volume knob. And I can also get a chopping noise related to the fizz when turning the volume knob in lower positions.

The problem exists in the Mustang V as well as described in my post in the "obnoxious tail end..." thread.Please peruse all the posts before making statements that could be misleading.
We wait and hope in Fender

My apologies. I spent 4 hours last night researching this and might have missed your post among the 17 pages on the other thread. I am glad that we are honing in on the symptoms and I would like to urge more people with the problem (such as you) to weigh-in and get involved in the discussion. The more apparent that the problem is affecting a great number of consumers, the more likely Fender will make it a priority to fix.

With that said, if Fender can acknowledge the problem, even if they don't have a fix yet, it would put many of us at ease. The silence is a bit troubling.

Also, is there anyone out there with a Mustang III, IV, or V that doesn't have this problem? If it is all III, IV, and V, then it might be noted that I and II have a higher Firmware.

Which part was misleading?

I said that "From what I heard, Mustang IV and V don't have problems." I admit, that the leading fact was incorrect. I didn't know, I am glad that I know now. In fact, this is affecting more people than it seems and we need to get these people on the thread to voice their findings.

Sorry guys but I don't think that's Digital Aliasing. Digital Aliasing is caused by frequencies that are beyond half of a device's sampling rate. I'm not sure what the Mustang's sampling rate is but let's say for the sake of argument that it's 48k. That would mean that anything beyond 24Khz would not be represented accurately because the vibrations (Hz) are faster than the A/D converter can properly convert. Most modern A/D converters employ a very steep low pass filter to prevent frequencies beyond the sampling rate's ability to capture from getting to the converter. Here's an excellent example from Wikipedia - http://en.wikipedia.org/wiki/File:Sawtooth-aliasingdemo.ogg

Still, even if Fender didn't employ that filter, and I can't see a reason why they would do that, the effect shouldn't sound like that "fizz" in the end. If there is aliasing you would hear it while the guitar is sustaining and as it decays. I think this is something else entirely. Could it be a Dithering/Bit Rate issue?

The weird thing is that I seem to remember my old '70s Fender Twin making very similar noises at the very tail end of a sustaining note.

O.

I dunno, I wish I knew more about this stuff. Dithering/Bit Rate could be the issue. I defiently hear it as it decays, too, though. It sounds like a phaser. And the tonal quality of the effect changes according to the volume of the note being played. That's why the noise changes as the volume know is turned. The "fizz" is always the same "note." It just changes it's (i don't know what the word is... timbre?). Like a wah opening and closing with just noise going through it. Or like a didgeridoo.

But anyways, the noise is there from the beginning to the end of the note, at least on my amp. It's just less noticeable on quicker notes, because, well, it's just not there as long.

Orcatraz, I had what you are describing with your old Twin. It was a bad pre-amp tube. If I remember correctly, it was in the piece of junk Route 101 amp I had. That thing wound up in the garbage. Bob

Why not edit the first post?

I have heard from people with Mustang V that this problem exists

I decided that I can't wait for the fix (Damn GAS) and I picked up the Mustang I

tested in store --- sounds perfect......no note decay issues at all.....maybe if they fix the mustang III, IV, V --- i will trade up, but for now as a small practice amp/toy this is all i need.

The Mustang III is the best value, as the $100 jump from the II to the III gets you a lot, the jump from the I to the II is not worth my $100

overall it does seem that the I and II do not have the same problems as the newer models....could be something in the manufacturing, or speaker design...i have no idea, I am not an engineer or tech wizard, but I do know the problem is wide spread with the newer designed III, IV and V

Fender? any idea if it is fixable?
the longer the silence from them on the matter leads me to believe that it is not fixable in this product run, and might be with a new model

i sure hope not, because I would love to get the III

I had this same sound in my ..... mp3 player .....
Turned out the interference came from the display and what's the main difference between the III,IV & V and the I & II Mustang amps, yes the display.
Just a hunch

Yes, probably so. That would be me mis-using the term. It is definitely digital and sounds like the low bit-rate files i would record on SoundEdit 16, or find on the internet before MP3's existed: basically a squaring-off of the waveform. You can hear the sound clip above, what do you think? Hoorah dithering!