#1
So after much searching, I bought a Mesa Express 5:50 (non plus). Its a head and 1x12 cabinet. Got a great deal on, so I'm pumped.

It sounds amazing, everything I wanted in an amp: great cleans, great mid gain, and a higher gain that I could only reach with a distortion pedal on my old amp.

I love it.

But, it has this nasty hiss on all the channels. I don't notice it in a band setting, or when playing loud, but when I play soft at home, it's kind of annoying.
Some google searches have lead me to believe that new tubes gets rid of the hiss, but it appeared that this only worked about half of the time.

A second option I ran into was using a noise gate or suppressor. I have no working knowledge of these things and was told that they only gated sounds that come before your amplified signal, so the amp's hiss wouldn't be gated. Is that true? If it is, could I just put a gate/suppressor in the effects loop then? Which would suit my needs better in this situation? A gate or a suppressor? I just want to get rid of the hissing.

Anyone have a third option/fix I could use?

Thanks in advance.
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#2
You will need back up tubes anyway so start with getting a few 12AX7s and swap them around to see what's what. I recommend JJs.

Hiss can come from lots of things really though and 'some' hiss is normal.

Gate should really be a last resort.
#3
This is beyond normal hiss though. Its more than I'd like though.

So new preamps? Alright, I've heard JJs sound to dark in this amp. I'll try em out though. I run a strat and a p90 equipped SG, so its hard to make them sound dark.
Quote by JD Close
Piano dick had some good parts, but should have said "As the business man slowly gets boned", would have accented the whole dick feeling of the album
#4
If you want to experiment further maybe get a JJ, a Tung Sol and then something like a JAN 5751 (drop in replacement for phase inverter slot).

I like:
www.dougstubes.com
www.valvequeen.com
www.eurotubes.com
www.tubedepot.com
www.kcanostubes.com


Also, before doing that, try swapping some existing tubes around to see if there is a difference. If you happen to have a good electronics contact cleaner (like Dioxit) you can spray the tube pins (not sockets) and work them in and out real good to clean.
Last edited by 311ZOSOVHJH at Jul 10, 2015,
#5
Some amount of noise and hiss is expected in any amplifier (usually I see it more in transistor amplifiers).

I have a good noise gate design (I designed it in university), but even with that I would not use it unless I absolutely needed it when using a high-gain distortion unit. Threshold settings and other artifacts from it make other playing styles difficult to keep it transparent.


A compressor is exactly what you do *not* need. It will amplify your quieter playing and increase the hiss a lot. What would help is an expander (exact opposite of a compressor), and a noise gate is like a crude form of expansion ("all" or "nothing", as opposed to varying the gain with the signal level).
Last edited by Blademaster2 at Jul 22, 2015,
#6
Hmmm, looks like its off to the tube experiments for me!
Quote by JD Close
Piano dick had some good parts, but should have said "As the business man slowly gets boned", would have accented the whole dick feeling of the album
#7
You could try the noise gate in the effects loop, and if the hiss cuts off there then it's something in the preamp. If it doesn't cut then it's something in the power amp.

Also, filter caps can hiss when they get worn out iirc. If your amp is squeaky clean and it's noticeably hissing, that's no fun. I would say if when micing the amp if the hiss is noticeable then you want to get it checked out.
#8
So this happens only at home but not elsewhere? Is it constant or does it vary as you move around?

I have a similar issue with a SS amp. So not sure if this applies to your situation. In my case I get static at work but not at home. From folks here I learned that it's electromagnetic interference. So it's not really a problem with the amp. It's a though thing to deal with. Have you tried playing in different rooms at your place?
#9
Try a JJ ECC803 in V1.
And clean all the phono sockets.
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#10
In my opinion, you shouldn't need a noisegate to fix this, especially for your clean channels. A clip to hear what the hiss sounds like and its volume would be helpful. Also, just want to make sure it is actually a hiss and not more of a buzz.

By the way- what kind of settings are you using? I'm not familiar with the express 5:50, but I notice from some photos that it looks like it has a global presence knob. If you are cranking the presence, that could give you hiss on all channels. Check your treble/presence settings. You may love your tone with the presence cranked, but you may have to compensate somewhere between gain/treble/presence.

I would start there before getting into the tubes (not that swapping tubes is that hard or a big deal); just to be thorough. While you're at it, it may be worth turning each knob down, one at a time, and see if it is associated with a particular knob. Its worth seeing if it hisses even with the master volume on 0. That type of shit-
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#11
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So this happens only at home but not elsewhere? Is it constant or does it vary as you move around?

I have a similar issue with a SS amp. So not sure if this applies to your situation. In my case I get static at work but not at home. From folks here I learned that it's electromagnetic interference. So it's not really a problem with the amp. It's a though thing to deal with. Have you tried playing in different rooms at your place?


that would be my guess. lights and TV's and computers, microwave ovens, etc. all can make even a perfectly good amp noisy. i would see if that was the issue and get a power conditioner.
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