Advice about noise from acoustic guitar amp - Nux Stageman AC50

[S_Bodi]

Dear all

I purchased the Nux Stageman AC-50 in February this year as a way to experiment at home with various sounds/loops/mics (https://www.nuxefx.com/stageman-ac50.html). Overall it's a nice amp with nice tones - I like it's tonal options more than similarly priced Fishman and Fender products. It's main problem at first was a sensitivity to powerline feedback but I've managed to improve this (and tolerate it).

One thing I noticed a while back (and I'm starting to wonder if it's becoming more obvious) is that bass notes give off a sort of subtle electrical tapping noise as they fade. For example if I strike the low E string, I'll get a nice clean sound but as the note fades I can hear a superimposed regular soft tapping noise (which is louder with higher gain or volume) and this very abruptly stops as the note dies off.

I found this on three separate guitars (two acoustic and one electric) and with two different cables.

The sound happens whether I have the amp on a carpeted floor or up on a higher surface - it's definitely not a cabinet rattle.

I can't hear the noise once I'm at about A# on the low string.

Interestingly I don't get any extra noises if I send the signal via DI out to my audio interface - so it's a problem with the amp's speaker system.

This amp has a 6.5 inch woofer and a 1 inch tweeter.

I'll likely send it back to seller to have a look but that involves shipping it out of town, and since I have limited amp experience (I've really only got into amplification this year) I thought I'd ask you guys to gauge how common these issues are and whether anyone knows of a fix.

Cheers

[jseth]

That amp has a rhythm circuit, right? Plays a variety of drum patterns... if that's "on" (even if you aren't using it), you could get a "pulse" from that effect that could bleed into the normal signal... same thing for vibrato, chorus, possibly even the looping function.

Make sure everything's "off" and see if you still get that odd noise... maybe try it without the wireless pedal board in the chain.

I've messed around with a few of those Stageman 50's and they seem like nice little amps; none of the ones I've played through (three or four of 'em) have had the issue you describe, although there's SO many features going on with that amp that it's easy to lose track of what is actually engaged and "in" the signal path...

[S_Bodi]

Thanks for the reply.

I've tried with everything turned off - I don't have the pedal but I can use the bluetooth app. It doesn't matter whether anything is on or off, or if the bluetooth app is connected or not.

I think I might have a dud unit. Even though there are few professional reviews of the amp, what I have found has been universally in praise and no mention of interference issues etc. Our house has modern wiring and nothing else picks up interference including a couple of amps my friend has loaned me and our AV equipment.

Since you've used a few - did you notice a flashing orange light within the unit whenever it's turned on? I asked NUX about this and they didn't get back to me, so I assumed it's normal behaviour.

In any case I think I'll get it back to the shop. I find these sorts of problems annoying because they are subtle but noticeable and sometimes vendors disagree that there's a problem, but I'll bite the bullet and send back.

[jseth]

Sounds like the way to go, this time... let us know how it all resolves for you.

[S_Bodi]

Took it to the supplier who is more local - agreed there is a noise. Will update when I hear back..

[S_Bodi]

Update - retailer called me saying he opened a new one and tested it and found no problems, so sent this to me. I can still hear it. It's like the unit does not handle bass sounds well at all. I can even get the problem to sound if I pick up with a Shure sm57 rather than a guitar pickup. I got two friends of mine to listen - they have more amp experience and they can hear it. I will ask for a refund I think.

I don't know but it seems that this thing bothers me more than others. I have to point it out to people but once I do it's unmistakable. It's not a cabling or location issue as I've tried it in a different location and with different cables and guitars. I'd be interested to know if anyone else has had such an experience with this or other amps.

[S_Bodi]

Final update - sent a recording of the sound to the retailer. They have offered a refund or store credit. They’ve been super cool about it, as I think they feel the sounds are acceptable for an amp.

I think the amp is overall good and good value for money, with nice tones, nice chorus and acceptable reverb (good for vocals and separate for each channel). It has great features - effects loop, DI and line out, separate three band EQ for each channel. I only briefly tried the looper and drum machine.

I guess for the price some quality has to be sacrificed and I think that’s what I experienced. I’m perhaps a bit sensitive to extra noises but I expect an acoustic amp not to have these issues. I went back and tried a bunch of other brands in a local shop and couldn’t reproduce the issue.

I wouldn’t tell anyone not to consider this amp but do demo it well in store.

Thanks for reading and I hope this is useful to others in the future.

[Johnhadleygrant]

Hi Guys
I have just purchased a Stageman AC-50 Guitar amplifyer and was shocked to hear the background noise coming from the speaker just as reported by your member S. Bodi.
I have tried Jazz bass guitar and a 6 string acoustic guitar with bridge piezo pickup. Both generate the same unwanted noise.
The ‘beating’ noise is much more noticeable in the bass frequencies, so that the noise when using the 6 string guitar is much more muted, but, its still there.
I have tried the following set ups to find where the noise is coming from..
Using D.I. Output to secondary mixer/amp NO NOISE
Using Send Output to secondary mixer/amp NO NOISE
Using Line Out to secondary mixer/amp NO NOISE
Same result on both channels.
Using or muting the chorus or reverb effects, colour or phase makes no difference.
Conclusion: The internal power amp is creating the unwanted noise.
TOTALLY unacceptable!
There is a serious design problem here.
Has anybody solved this issue?
Thanks for any feedback!