Mesa Bass 400+ Noise??

nsh50a · #1 03-17-2011, 01:09 PM

I have an older 400+ that i've used for the past 8 years. I absolutely love it's tone but it has one thing that has annoyed me for years. Every time you switch it off of standby it makes a series of low volume pops as well as some hiss/hum. After about 5 minutes of being on it no longer makes the pops so it's not a huge issue. It is mainly used in a church setting however and therefore I can't turn it onto standby during the sermon as when We go back up to play the last song if i switch it off of standby it pops for the next 5 minutes. I just replaced all the tubes Pre/Post with a set of JJ's from eurotubes hoping it would solve the problem (it needed new tubes anyway) however the sound is still there. The sound is not affected by either the master or pre-amp volumes and will will occur even when everything is set to 0. I made a short video showing what it does at YouTube - Mesa Bass 400+. Any body got any ideas on what it could be? I'm pretty handy with a soldering iron (have made several pedal on my own etc) and unfortunately there is not tech in my state (Missouri) I'd trust with a tube amp like this.

Caca de Kick · #2 03-17-2011, 01:20 PM

If you can't switch it to standby because of the noise being annoying, then use a tuner pedal as a mute.

My 400 has always made a quiet pop when switching on from standby, but I never used it in a church setting so it didn't matter.

CDweller · #3 03-17-2011, 01:26 PM

Quote:

Originally Posted by nsh50a

I have an older 400+ that i've used for the past 8 years. I absolutely love it's tone but it has one thing that has annoyed me for years. Every time you switch it off of standby it makes a series of low volume pops as well as some hiss/hum. After about 5 minutes of being on it no longer makes the pops so it's not a huge issue. It is mainly used in a church setting however and therefore I can't turn it onto standby during the sermon as when We go back up to play the last song if i switch it off of standby it pops for the next 5 minutes. I just replaced all the tubes Pre/Post with a set of JJ's from eurotubes hoping it would solve the problem (it needed new tubes anyway) however the sound is still there. The sound is not affected by either the master or pre-amp volumes and will will occur even when everything is set to 0. I made a short video showing what it does at YouTube - Mesa Bass 400+. Any body got any ideas on what it could be? I'm pretty handy with a soldering iron (have made several pedal on my own etc) and unfortunately there is not tech in my state (Missouri) I'd trust with a tube amp like this.

Mine does the same thing, and it's pretty much brand new. I bought it new in the box in January of '10, and haven't used it very much at all. I'm in contact with Mesa, and they want me to do so testing on the amp, which I will when I get some free time next week. The tech said it might be a bad tube or resister. Whatever it is, the popping and hiss out of this amp is so bad that I wouldn't consider using it on stage. Mine actually hisses and pops a lot louder than yours did in the YouTube vid, but that might be because I have it hooked up to four GK 112 Neo ll cabs stacked one on top of the other, ie more speaker area than in your vid. Great sounding amp, but at this point it's useless because it's too noisy.

nsh50a · #4 03-17-2011, 02:15 PM

Right now I am using a volume pedal at the end of my pedal board. The only problem is that by not being able to switch it to standby, it adds a good 3 hours a week of "on-time". Just looking out to keep the glass as poppin fresh as possible. I am glad to hear that it is not this amp alone. I've loved the tone and always thought it was due to it being an older amp (this one is a late 80's model). In the video I had it hooked to a lone 1x15. On stage it is paired with an ampeg 810 and is considerably louder. The pops only last the first few minutes that it is turned on however. After being on for 5 minutes its as quiet as i would expect a tube amp to be.

Caca de Kick · #5 03-17-2011, 02:27 PM

It's still "on" either way.

The only thing the standby is doing is no output to the speakers. But the tubes are being heated and being 'used'. It's not preserving them any less.

runmikeyrun · #6 03-17-2011, 03:13 PM

if it's older and never had a cap job it could be bad caps popping.

anderbass · #7 03-17-2011, 03:39 PM

Something really easy you could try is patching your effects send/return jacks with a short guitar cord. (try this with both the front and back fx-loops, one loop at a time)

Might as well try exercising your effects blend knob back and forth a few times, and then make sure you leave it set back to 0 (unless your using fx's in the loop) too.

It doesn't sound like these are your issue but they're free/easy things to try and you just never know...

nsh50a · #8 03-17-2011, 08:42 PM

That's a good thought. I had previously ran the back effects out to an Avalon D5 DI and still had the problems then but it's worth a try bypassing both the front and back loops. Tonight I ran the DI from the slave output and it did seem like the pops were less however it was also hooked up to a power conditioner tonight (it is normally hooked up to one and was making the pops previosly though). I had also considered the caps but figured the amp would need to be 40-50 years old before the caps start going