Are there some tubes in there? My Axe-Fx II is microphonic!

Patzag

Patzag

Fractal Fanatic
I was doing some tests with my wireless unit to compare noise levels and had the gain cranked on a patch when I noticed that unplugging the cable from the input produced some mechanical noises. I pulled the plug and tapped the case of my Axe II and was shocked at hearing noise coming out of my speaker. In fact, the case unit is microphonic. scratching it or tapping it results in noises in my speaker.
Worse: increasing volume results in feedback! With nothing plugged in but my speaker, the case of the Axe II acts as a microphone and resonates and ultimately feedback.

So here are a few more facts that might help:

Decreasing the AD input level INCREASES the noise level.
Changing to digital input reduces noise to 0
Changing from front to rear input changes character of noise, but not its existence
Output boost/pad changes nothing
Plugging in instrument does not change microphonics

Now that's really strange. So I thought: Ah ah ... that's how Cliff did it: there's a hidden tube in there that's disguised as an IC chip.:mrgreen

But seriously ... Has anyone encountered that or could test this with their units? The last thing I'd like to find out is that my Axe is defective. FWIW, I was using the standard SOLO100 LEAD preset and just cranked the output level, no special anything.
 
Is the input maybe set to L+R Sum,? If yes, try Left Only (I/O).
Also, on my system I turned down the levels of Input 1 and Inoput 2 in I/O.
 
Anything with lots of gain will be microphonic to some degree. If you pull the input cable you exacerbate the microphonics by orders of magnitude since there is no load.
 
FractalAudio said:
Anything with lots of gain will be microphonic to some degree. If you pull the input cable you exacerbate the microphonics by orders of magnitude since there is no load.
Click to expand...

First thanks for letting me know this is apparently not abnormal.

Plugging in a guitar makes no difference whatsoever. The system is just as microphonic. Interestingly enough, I plugged into Logic and examined the signal on the Channel EQ analyzer. With the output turned almost all the way down, (turning it all the way off shuts down the signal going into Logic through USB), and with the gain set just per the preset, nothing added, tapping the case, with a guitar plugged in or not, results in microphonics being picked up and recorded into Logic. This is pretty amazing to me.

Did anyone else try this?

Yek: I tried all that. No change. With input 1 and 2 at 0, the system is just as microphonic. The only thing that reduces the microphonics is INCREASING the Instrument input in I/O !
 
FractalAudio said:
Microphonics are normal. Try cranking up a tube amp and tapping on the chassis.
Click to expand...

I know! And that's what makes me smile about all this rather than freak out. We're talking the ultimate in modeling. I wonder of the S-gear pluggin discussed elsewhere rings out when you tap the computer monitor :lol!
 
Hi everyone, I had the same exact problem at a Live Show.. Back in July, 3 days after I picked up The Axe Fx II in NH, I was using it with the stock Factory presets at a Show with a Full Sound System and very loud stage volume. My set up was a Jackson SL-1 into a AKG SR4000 into the Axe Fx II , from there into a Rocktron Velocity into a Mesa 2-12 Cab. There was no time to tweak anything so I went with the stock presets and during sound check heard the Microphonic Feedback...It sounded exactly like a Pre-amp tube that was about to blow... Sound man was annoyed, I couldn't figure it out in time so I had to deal with it...
During the show The Axe Fx totally blew me away it sounded amazing..I had the Ultra for about 9 months and was happy after all the tweaking but this sounded amazing right out of the box...!! Even my drummer noticed the difference and commented on how much better it sounded... It was all there Touch Dynamics, Sound etc... Amazing ..!!
So when I got home at 1:00am I set-it all up again and started troubleshooting.....

It Turns out that the Chassis from the AKG SR4000 was touching the Axe Fx II Chassis and causing a Ground. I remounted everything in my rack to make sure everything was separated and not touching and it solved the Problem... Microphonic feeback was gone.... !!! You might want to try this...

Good Luck,
Rain
 
Yes it is. I'd like to ask others to test this please. I have no ground issues with my rig. There's only one thing in my rack and that's the Axe II. I'd like to know if anybody else has this issue.
 
I'm having this same issue. The case is very microphonic when I have a higher gain patch on. If I turn the output knob up, I get feedback even with the guitar volume off. The fan is also adding to the problem. On the higher gain presets I can hear a hum through the outputs that is the same frequency as the fans hum. To confirm, I removed the lid and held it a 1/2" or so over the Axe2's chassis. The hum went away. Seems like the fan's vibration affects the Axe2's case and eventually the output signal. Curiously, when I removed the Axe2 from my rack and layed it on the carpeted floor, the humming is reduced quite a bit. To minimize the hum and the internal feedback I ended up reducing the master on my amp blocks. It's much lower than I'd like, but I guess it's what needs to be done.
 
Some of the higher gain patches in the II accentuate the microphonics inherent in the unpotted pickups I have in my semi-homemade Les Paul.

I like it. I can actually speak into the neck pickup and have it come thru the Axe with some settings. Great special effect.

I also find the unpotted pickups are much easier to send into controllable feedback, even thru cans.

In this case, I'm having more fun running with it than fighting it...

YMMV
 
claudel said:
Some of the higher gain patches in the II accentuate the microphonics inherent in the unpotted pickups I have in my semi-homemade Les Paul.

I like it. I can actually speak into the neck pickup and have it come thru the Axe with some settings. Great special effect.

I also find the unpotted pickups are much easier to send into controllable feedback, even thru cans.

In this case, I'm having more fun running with it than fighting it...

YMMV
Click to expand...

100% same here. Swapped pickups on my PRS because of it...
 
al
jmpatrick63 said:
I'm having this same issue. The case is very microphonic when I have a higher gain patch on. If I turn the output knob up, I get feedback even with the guitar volume off. The fan is also adding to the problem. On the higher gain presets I can hear a hum through the outputs that is the same frequency as the fans hum. To confirm, I removed the lid and held it a 1/2" or so over the Axe2's chassis. The hum went away. Seems like the fan's vibration affects the Axe2's case and eventually the output signal. Curiously, when I removed the Axe2 from my rack and layed it on the carpeted floor, the humming is reduced quite a bit. To minimize the hum and the internal feedback I ended up reducing the master on my amp blocks. It's much lower than I'd like, but I guess it's what needs to be done.
Click to expand...

Hmm.. I'll be watching for this when I test my new II. If it goes away when you pull the lid or put the Axe on carpet, then there must be some physical\mechanical way to improve it on the Axe itself. Did you make sure all the screws\bolts holding the board, fan and case together were tight? Maybe some simple fix, like rubber washers under the lid or fan bolts?

This sounds similar to an experience I once had with a handmade 18 watt Marshall clone. It had this mystery amplified microphonic hum at high gain with volume. It took a long time to track down but it turned out to be the way the chassis was physically mounted inside the headshell. Just this weird little vibration from one corner where two metal edges made contact. It was the sort of thing where if you had two identical heads side by side, they would look the same, nothing would appear wrong on either one, but one would be fine while the other vibrated. Just a very minor mechanical fit inconsistency. It drove me crazy until I pinpointed it and fixed it..
 
Robboman said:
al

Hmm.. I'll be watching for this when I test my new II. If it goes away when you pull the lid or put the Axe on carpet, then there must be some physical\mechanical way to improve it on the Axe itself. Did you make sure all the screws\bolts holding the board, fan and case together were tight? Maybe some simple fix, like rubber washers under the lid or fan bolts?
Click to expand...

I tightened the fan, although it was petty tight already. Maybe we need something liquid cooled?
 
claudel said:
Some of the higher gain patches in the II accentuate the microphonics inherent in the unpotted pickups I have in my semi-homemade Les Paul.

I like it. I can actually speak into the neck pickup and have it come thru the Axe with some settings. Great special effect.

I also find the unpotted pickups are much easier to send into controllable feedback, even thru cans.

In this case, I'm having more fun running with it than fighting it...

YMMV
Click to expand...

Scott Peterson said:
100% same here. Swapped pickups on my PRS because of it...
Click to expand...

I'm really digging the unpotted humbuckers I have.

Motor City Pickups is in your neck of the woods, I believe. Wade's great with making a vague description into a great pickup.

They're just shy of uncontrollable but have that extra little something going on that I really love enough to not mind a bit of noise.

I'm gonna try and get some tracks down this fall, so that'll be the test as to if they're too noisy or not
 
I guess I'm re-igniting this thread. Since moving to using my AXE II at live shows, I've unfortunately discovered it is as microphonic as a, well, a goddamm microphone. It howls and moans when I get to stage volume and it is totally unusable. It has caused me severe embarrassment at several gigs where I hit a high gain patch (a preset I created in the studio) only to have the solo drowned out by the unit's feedback through an RCF monitor drown out my solos. I'm absolutely staggered that so few players report this problem.
Are there only bedroom players on this forum?
 
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