Does anybody have an idea what this hum might be?

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Random Hero

Random Hero

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I have a low level hum on my Shiva. I've tried different outlets in the house and it seems to be the same/similar. Can't recall hearing it at gigs but then everywhere else is louder and it's pretty quiet here!

Happens on every channel, whether something is plugged in or not, and no matter where the volume is. It doesn't change with the volume up or down, is what I mean. Also tried different power tubes and it didn't seem to change.

To give you an idea of how quiet it is, once the amp gets up to about 10 o'clock on the master volume, the hiss pretty much drowns it out, though you can still detect the frequency of the buzz if you listen.

Any thoughts?

You can hear it here...
 
So I've been reading up on this stuff most of the day.. One of the things I read was that if I remove the PI, it stops anything getting to the power section, meaning if you hear no hum/buzz, then the problem is before that? Well, I pulled the PI, and it was silent. I've swapped out all of the preamp tubes, and it's made no difference.

It makes sense to me - effectively a layman - that the preamp is amplifying something but this happens with the volume on 0, with nothing plugged in and on both channels. If you turn the master up, the hiss of the amp sort of drowns the buzz out but you can still hear it in there if you listen.

Is it possible it's just the power in my apartment? Maybe a neighbour has plugged something in that's messing with my power?

Anybody have any ideas what else it could be?
 
Try spraying the shit out of the input jack with Deoxit, and then run the cord in and out of the input. Respray, and repeat... Spray all the 1/4" female sockets and tube sockets while you're at it.
 
This happens with nothing in the jack though? Still do it?
 
Random Hero":9cpuasl4 said:
This happens with nothing in the jack though? Still do it?
Click to expand...
Yes.

Does the Shiva use a series loop? If yes, try plugging directly into the effects return... Does the hum stop?
 
TrueTone500":1hw2vwbf said:
Random Hero":1hw2vwbf said:
This happens with nothing in the jack though? Still do it?
Click to expand...
Yes.

Does the Shiva use a series loop? If yes, try plugging directly into the effects return... Does the hum stop?
Click to expand...

Nope.

Basically the only way I can get it to stop is to remove the PI tube. I've tried every other preamp tube out of the circuit, as well as all of them out at once. No luck.
 
You don't need to remove the PI valve. If the hum increases when you advance the MV, then the problem is in the preamp section. If the hum does not increase when you advance the MV, it's in the power section. I suspect it's a grounding issue. First clean all connectors, inputs, and sockets with Deoxit silver.
 
Cleaning with deoxit is a good idea.I would Try some different preamp tubes
 
With every preamp tube but the PI out, it hums. With the PI out and every other tube in, it's dead silent. I'm guessing it has to be something to do with the PI area?
 
I have to admit... I have my speakers turned up all the way, with my ear to the speaker and I don't hear anything but the normal hiss of an amp.
 
I just had a similar issue , turned out to be the first position preamp tube. It is a touchy spot with some amps.
 
FourT6and2":1id8g7tv said:
I have to admit... I have my speakers turned up all the way, with my ear to the speaker and I don't hear anything but the normal hiss of an amp.
Click to expand...

I agree
 
Random Hero":2h167xt1 said:
I have a low level hum on my Shiva. I've tried different outlets in the house and it seems to be the same/similar. Can't recall hearing it at gigs but then everywhere else is louder and it's pretty quiet here!

Happens on every channel, whether something is plugged in or not, and no matter where the volume is. It doesn't change with the volume up or down, is what I mean. Also tried different power tubes and it didn't seem to change.

To give you an idea of how quiet it is, once the amp gets up to about 10 o'clock on the master volume, the hiss pretty much drowns it out, though you can still detect the frequency of the buzz if you listen.

Any thoughts?

You can hear it here...
Click to expand...
I owned a 20th Shiva as well. Mine had a buzz at idle with or without the jack. I isoalted the issue if you want to call it that. It can be annoying but it's really not that bad. We sometimes wind up focusing on these types of noises. On my amp it was EMF that was being picked up by two specific large ceramic caps near the power section. If I would put my finger in certain areas around the caps without touching anything my body would act as a ground and the hum would get much less. I even did a few other troubleshoot experiments. It is probably the same thing. If it is I can probably help you make it much less. It will always be there but I would consider it normal for this amp. It has to do with the way the power area is designed and laid out. Some Shivas will have it as others will not. Before I was able to figure out what was going on I sent my amp to Bogner under warranty. They rewired the power section with tighter twists,etc.. on the high voltage leads to try and cancel it out. It came back with the same hum and then I found the issue. If you can make it a little quieter I would not worry about. Let me know if you want to know what I did after you try what I did with your finger. Oh, and I cannot hear it from your video as well but I know what you are talking about.
 
glip22":30hu8o98 said:
Random Hero":30hu8o98 said:
I have a low level hum on my Shiva. I've tried different outlets in the house and it seems to be the same/similar. Can't recall hearing it at gigs but then everywhere else is louder and it's pretty quiet here!

Happens on every channel, whether something is plugged in or not, and no matter where the volume is. It doesn't change with the volume up or down, is what I mean. Also tried different power tubes and it didn't seem to change.

To give you an idea of how quiet it is, once the amp gets up to about 10 o'clock on the master volume, the hiss pretty much drowns it out, though you can still detect the frequency of the buzz if you listen.

Any thoughts?

You can hear it here...
Click to expand...
I owned a 20th Shiva as well. Mine had a buzz at idle with or without the jack. I isoalted the issue if you want to call it that. It can be annoying but it's really not that bad. We sometimes wind up focusing on these types of noises. On my amp it was EMF that was being picked up by two specific large ceramic caps near the power section. If I would put my finger in certain areas around the caps without touching anything my body would act as a ground and the hum would get much less. I even did a few other troubleshoot experiments. It is probably the same thing. If it is I can probably help you make it much less. It will always be there but I would consider it normal for this amp. It has to do with the way the power area is designed and laid out. Some Shivas will have it as others will not. Before I was able to figure out what was going on I sent my amp to Bogner under warranty. They rewired the power section with tighter twists,etc.. on the high voltage leads to try and cancel it out. It came back with the same hum and then I found the issue. If you can make it a little quieter I would not worry about. Let me know if you want to know what I did after you try what I did with your finger. Oh, and I cannot hear it from your video as well but I know what you are talking about.
Click to expand...

Hey man. I took it to a tech last week, and it came back a little less buzzy but it is still there. He re-set the bias (apparently it was way too hot) and it did decrease it ever so slightly. He was stumped about the hiss/buzz/hum/whatever you wanna call it and is waiting for a schematic from Bogner to take another look.

Curious to know what you did?
 
Before you start thinking its caps and other weird things, think two things right away. First, EMI. Refrigerators, televisions, cell phones, appliances, and other electronics can cause EMI and interfere with our guitar's pickups. If you notice that the sound is different at certain parts of the day, or with your guitar facing a certain direction from the amp, chances are EMI is to blame. Lastly, preamp tubes in my experience sometimes need to be reseated, more often than not, in order to get things sounding right at times. I always do the tapping glass trick with my preamp tubes in V1 (and sometimes, depending on the amp, V2) to make sure it isn't microphonic in that crucial spot with the amp's volume quite high. If I hear strange clanking/oscillations coming through the speakers, I know that the tube is either bad or may not be best suited to be in the V1 position.

Those two things are what I'd spend time toying with first and foremost. Then move on to other solutions. Don't get me wrong, things do happen that aren't always tube or EMI related (just recently I found out that I had two bad caps in my Twinolux which caused the tremolo to be nonexistent), but more often than not my issues are always EMI or preamp tube related. It's been my experience that most preamp tubes that are sold are horrible. Conversely, some amps are also more finicky than others when it comes to preamp tubes. My Twinolux and my Ventura are like that. My Twinolux is especially finicky to what tube I put into V1, where past amps I've had (Roadster and Royal Atlantic) are less so.

Anyways, just thought I'd throw out my experiences as my own .02 cents. Clearly, from what I've read, you and your tech have a more mysterious and elusive issue in the amp. Perhaps there's a bad ground somewhere?

Good luck!
 
guitarrhino":1xxms85d said:
Before you start thinking its caps and other weird things, think two things right away. First, EMI. Refrigerators, televisions, cell phones, appliances, and other electronics can cause EMI and interfere with our guitar's pickups. If you notice that the sound is different at certain parts of the day, or with your guitar facing a certain direction from the amp, chances are EMI is to blame. Lastly, preamp tubes in my experience sometimes need to be reseated, more often than not, in order to get things sounding right at times. I always do the tapping glass trick with my preamp tubes in V1 (and sometimes, depending on the amp, V2) to make sure it isn't microphonic in that crucial spot with the amp's volume quite high. If I hear strange clanking/oscillations coming through the speakers, I know that the tube is either bad or may not be best suited to be in the V1 position.

Those two things are what I'd spend time toying with first and foremost. Then move on to other solutions. Don't get me wrong, things do happen that aren't always tube or EMI related (just recently I found out that I had two bad caps in my Twinolux which caused the tremolo to be nonexistent), but more often than not my issues are always EMI or preamp tube related. It's been my experience that most preamp tubes that are sold are horrible. Conversely, some amps are also more finicky than others when it comes to preamp tubes. My Twinolux and my Ventura are like that. My Twinolux is especially finicky to what tube I put into V1, where past amps I've had (Roadster and Royal Atlantic) are less so.

Anyways, just thought I'd throw out my experiences as my own .02 cents. Clearly, from what I've read, you and your tech have a more mysterious and elusive issue in the amp. Perhaps there's a bad ground somewhere?

Good luck!
Click to expand...

Except he's getting the noise without anything plugged into the amp. So that will rule out EM/RF being picked up by the guitar.
 
Try taking a small patch cable and jump your effects loop. Plug in to your send and the other end in return. Change anything?
 
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