50 Caliber + noise

[jerry.adams]

Hey all,
I picked up a 50 Caliber+ chassis at a yard sale for $8. I put tubes in it, hooked up a speaker and it sounds great, however it is very noisy when a guitar is plugged into the input. When nothing is plugged in, there is very little noise. I've swapped tubes, checked for loose grounds, all with no improvement. Any suggestions would be greatly appreciated. Thanks.

 

[tonejam]

you're not having a joke with us, are you? Eight dollars?
Hey, congratulations, what a bargain! I have no advice to offer, except to say, even if you have to pay a tech to fix the problem, you're still gonna come out a winner!

 

[jerry.adams]

Yup no joke, 8 bucks! I agree that even if i take it to a tech I still got a great deal, but I like servicing my gear or at least attempting to. Lol.

 

[Sp3ktral]

check the input/loop/all 1/4" jacks for corrosion/dirt?

contact cleaner!

 

[Blueracer]

Nice score. I am assuming that the noise you are hearing is 60 hertz type of noise (buzz as opposed to static). First thing to try is a different guitar cable or try the cable and guitar into another amp and make sure as a unit they are ok. Next thing you can try is the ground switch on the back of the amp. It has three positions. Usually it should be in the center but try all three positions and see if it makes a difference. If one of the positions kills the noise and it is not in the center position then you have a ground issue at the power plug. Next try disconnecting the guitar but leave the cable plugged into the amp. This should make the noise worse. Take a wire and connect it across the two connections of the cable. This should ground the input and kill the noise. If it doesn't then the ground connection at the input jack at the amp is not grounded and needs to be reconnected. Try these things and post back what you find.

 

[jerry.adams]

Thanks for the responses guys. The only thing that made a difference was shorting the guitar cable. It didn't completely kill the noise, but brought it down to a level that seems normal. What next? I've heard that these amps are noisy by nature, any other suggestions? Thanks for the help, I really appreciate it.

 

[Blueracer]

If shorting the input cable killed the noise it would suggest that the amp is ok. That leaves the guitar as the culpret. Have you tried the guitar and cable in another amp to make sure that one of these items is not the cause of your noise. Also is the noise more of a buzz (60 hertz pickup) or is it more like static (more of a hiss).

 

[jerry.adams]

There is definitely some noise from the pickups (the level of the noise changes relative to the location of the guitar). But there is also a background noise(I would describe it as a hiss) that increases as the gain, master and lead master are turned up. My other amp is a Hot Rod Deville, it is much less noisy with the same guitar(Strat Plus with Gold Lace Sensors). I have new filter caps on the way, although I don't suspect that that is the issue, but I think I'll replace all the electrolytics while I'm at it and touch up all of the solder joints while I'm at it. I gigged with this amp last Friday and everyone in the band commented on how great it sounded, I just wish it was a little less noisy.
I also have Electro-Harmonix 12AX7's in it, I don't know if there is a better tube that would give me less noise.

 

[Blueracer]

Ok a couple of comments here. First having the guitar pick up the more 60 hertz sort of noise (more of the buzz sort of noise) and having it position/location dependent is normal. Single coil pickups (Fender Strats, Teles, etc) are more susceptible than double coil Humbucker pickups (Gibsons). For instance I definately notice the difference in noise level when I am playing my Strat near my computer monitor than away from it. The in between positions of the pickup selection switch helps with Strats as they put coil pairs into the circuit but out of phase which tend to cancel the 60 hertz type noise. I don't have experience with Lace pickups but my impression is that these pickups were designed to decrease this sort of noise pickup. Good grounding and good cables will help with this sort of noise.

Now the other sort of noise, the hiss type, is another matter. This sort of noise is caused by random electron movement in the circuits themselves. This random movement is caused by heat and is a normal and unavoidable process. The more gain you have in the amp the more this sort of noise is amplified and gets to the speakers. That there is more noise as you increase gain is normal. It should be noted also that the tubes earliest in the amplification chain will have the most effect on the total noise developed by the amplifier. So from a noise perspective V1 is the tube that contributes the most V2 next and so on. That being said there is something you can do which is to use low noise tubes and put them in the V1 and V2 positions. For instance 7025 tubes are low noise versions of 12AX7 tubes. I don't know if Electro-Harmonix 12AX7s are noisier by nature however individual tubes will just be more or less noisy as a matter of course. Try swapping the tubes around to lower the overall noise. Also note that turning the volume up will have more effect on noise than the master (but not necessarily the lead master). You will experience more noise in lead mode than rhythm (more gain stages amplify the frontend noise more).

You are right that the filter caps will probably not help with the noise issue however you are doing the proper thing by replacing them if the amp is very old and it doesn't appear that these caps have been replaced. Just a good maintennance thing to do.

One last comment. Mesa Boogie amplifiers are really high gain amplifiers so they will naturally produce more noise than your Hot Rod Deville (I am assuming that the Fender is lower gain). It just goes with the territory. If you really still think that the amp is overly noisy it may be time to consult a tech. It is difficult at best to diagnose and fix these sorts of things using the board as an intermediary. Hope this is helpful.

 

[jerry.adams]

Thanks for the help, I think I'll try swapping some tubes around and see what happens.

 

[Blueracer]

Good luck. Let the group knows how this turns out. It is how we all learn.

 

[Blueracer]

Found this evaluation of 12ax7 tube performance. fyi.

http://thetubestore.com/12ax7review.html

 

[Monsta-Tone]

I would definitely start with a tube swap.
If it's happening in both channels, I would start with V2.
If it's only the lead channel, V1 would be the most likely suspect.

With some of the .50 Cals, there are carbon composition resistors tied to the plates of the preamp tubes.
These sound really good when they are new, but start to introduce hissing sounds as they age.

These are the 100k resistors that feed the high voltage to your preamp tubes.
If the input cable is grounded, or if the guitar is not plugged in, there will be very little noise.
If the guitar is plugged in, then the noise will magically appear.
This noise will occur whether the guitar is turned up or not.

If the noise only occurs when the guitar is turned up, then the issue is one of the following....
Power in your house may be dirty.
Amp may not be grounded properly (either at the wall plug or internally).
Your guitar cord is faulty or noisy.
Your amp is picking up hum from something.

If the problem only happens when the guitar is turned up, try the following.
Different cord.
Different guitar if you have one.
Move the guitar from side to side or farther away from the amp.
Do not face the amp.

If the problem still exists, your best bet is to try the amp at a friends house with his guitar and cable. This will completely rule out everything in your house.

 

[mule#1]

There is definitely some noise from the pickups (the level of the noise changes relative to the location of the guitar). But there is also a background noise(I would describe it as a hiss) that increases as the gain, master and lead master are turned up. My other amp is a Hot Rod Deville, it is much less noisy with the same guitar(Strat Plus with Gold Lace Sensors). I have new filter caps on the way, although I don't suspect that that is the issue, but I think I'll replace all the electrolytics while I'm at it and touch up all of the solder joints while I'm at it. I gigged with this amp last Friday and everyone in the band commented on how great it sounded, I just wish it was a little less noisy.
I also have Electro-Harmonix 12AX7's in it, I don't know if there is a better tube that would give me less noise.

I would definitely try new tubes in V1 and V2

What do filter caps do and what will replacing them do for the amp? Will the tone improve? I've considered sending my C=+ to have it done.

 

[jerry.adams]

So I swapped some more tubes around with no improvement. Then I got some contact cleaner and cleaned all of the jacks, pots, etc. and lo and behold she is as quiet as can be! I guess maybe I should have started with that at the beginning. It's a wonder what a little routine maintenance can do. Thanks for all of the help guys. Now I'm going to put a proper reverb pan in it. Thanks again.

 

[dodger916]

What do filter caps do and what will replacing them do for the amp? Will the tone improve? I've considered sending my C=+ to have it done.

Replacing old filter caps can definitely improve tone. As they age, the caps lose some of their dynamic range, and replacing them can restore that range. For instance, when I had my C+ "blueprinted" by Board member Boogiebabies (Ed), I noticed a definite improvement in the amount and quality of the bass response. It was deeper and more Fenderish. The highs were also more pleasant, which I think also had to do with the bright mod Ed performed.

Rob: I would highly recommend sending your amp to Boogiebabies. He knows these amps as well as anyone, including Mike Bendinelli. He went through my C+ with a fine-toothed comb and completely blueprinted it. It was like having a brother work on the amp. We should chat about this when we meet next in Ithaca, or give me a call to discuss.

 

[mule#1]

Awesome! I'll have to clean mine up now lol.

 

[mule#1]

What do filter caps do and what will replacing them do for the amp? Will the tone improve? I've considered sending my C=+ to have it done.

Replacing old filter caps can definitely improve tone. As they age, the caps lose some of their dynamic range, and replacing them can restore that range. For instance, when I had my C+ "blueprinted" by Board member Boogiebabies (Ed), I noticed a definite improvement in the amount and quality of the bass response. It was deeper and more Fenderish. The highs were also more pleasant, which I think also had to do with the bright mod Ed performed.

Rob: I would highly recommend sending your amp to Boogiebabies. He knows these amps as well as anyone, including Mike Bendinelli. He went through my C+ with a fine-toothed comb and completely blueprinted it. It was like having a brother work on the amp. We should chat about this when we meet next in Ithaca, or give me a call to discuss.

Thanks Frank! We will definitely discuss this.

 

[Sp3ktral]

glad that you were able to get rid of that noise!

what's the chance of getting pics of this $8 amp??