amp noise?

[guitaristdan103]

hi dudes, i've picked up a roland bolt 60 watt, valve amp. and when trying to record it, there's a fairly strong "humming noise' coming from it, and ruins the recordings. it's an 26 yr old amp, so i dunno if its too old or.. there's something else. could it be a grounding issue?

I know tube amps are supposed to be quite noisy, but i dont think it should be this noisy, so im pretty sure there's somethibng wrong with it, if u got any ideas i'd appreciate it. I also changed the power tubes to mesa boogie ones.

thanks dan

 

[mjbphotos]

Does it hum when no guitar is plugged in? Only when turned up loud? Usually hums are from a grounding problem. Try plugging into a different circuit.

 

[guitaristdan103]

yeah, it doesnt matter what volume or if a guitar is plugged in or not, it just keeps humming, must be a grounding issue then?

 

[Sonixx]

My guess is the power supply filtering caps should be replaced.

Is the power cord a three prong cord? If not, have the tech replace it also.

 

[guitaristdan103]

I think its the speaker cable, where the wires from the 'amplifier section' to the speaker connect. There's two wires in teh cable connecting them. The guy that used to own it changed the speaker from the original roland speaker to a lorenz speaker, i dunno if he could of missed something? Akso when i move the cable slightly, the hum dissapears, so its go to be something with that cable.

 

[ggunn]

I think its the speaker cable, where the wires from the 'amplifier section' to the speaker connect. There's two wires in teh cable connecting them. The guy that used to own it changed the speaker from the original roland speaker to a lorenz speaker, i dunno if he could of missed something? Akso when i move the cable slightly, the hum dissapears, so its go to be something with that cable.

The speaker cable could be bad, but that's not what is causing the hum. If it hums without anything plugged into the input, it's not likely a grounding issue.

The fact that the hum goes away when you jiggle the speaker cable is a bit worrisome, though. It could be that the cable is shorting or opening up; if that happens while you are playing it could severely damage the amp.

My money is on power supply filter capacitors going bad. Adding a three conductor power cable to the amp if it doesn't already have one is an excellent idea whether or not it has anything to do with the hum.

 

[Lt. Bob]

The speaker cable could be bad, but that's not what is causing the hum. If it hums without anything plugged into the input, it's not likely a grounding issue.

The fact that the hum goes away when you jiggle the speaker cable is a bit worrisome, though. It could be that the cable is shorting or opening up; if that happens while you are playing it could severely damage the amp.

My money is on power supply filter capacitors going bad. Adding a three conductor power cable to the amp if it doesn't already have one is an excellent idea whether or not it has anything to do with the hum.

ditto ....... there's no likely way a speaker cable could cause hum.
If the hum goes away when you jiggle it, then it's probably stopping ALL sound and not just the hum.

I suppose it could be remotely possible that when you jiggle the speaker cable it's moving something that's loose in the amp like the speaker jack or something close by and making a ground connection that's otherwise bad thus stopping the hum.
But that's a pretty remote possibility.;

 

[ocnor]

The first thing to do is get a can of Deoxit D5 and spray the crap out of all of the jacks and pots. Once you've eliminated any of those things as the problem then you can begin trouble shooting.

 

[Transcend]

i actually had this problem with my tsl601 when i got it.

and it turned out the amp was biased way too high

it was meant to be 80mv and it was biased to 110 causing hum across all channels because well the tubes were cooking themselves.

so i would say check the bias on it also.

 

[guitaristdan103]

i actually had this problem with my tsl601 when i got it.

and it turned out the amp was biased way too high

it was meant to be 80mv and it was biased to 110 causing hum across all channels because well the tubes were cooking themselves.

so i would say check the bias on it also.

Possibly... i've put new mesa boogie power tubes on it about 3 months ago (use to have groove 6l6 tubes before). I'll put some old tubes on it and see if it goes away. But its going to a tech tommorow, cause i don't want to mess around high voltage stuff!!

 

[Transcend]

also thats another thing certain tubes are noisier than others.

I have never really looked into the mesa ones as i presume theyre just same as the marshall/fender types ones.

Just cheap crap rebadged as the company using them.

Hope you manage to get it sorted out.

 

[guitaristdan103]

got the amp back today from a tech who works next to our factory, and is not as noisy as before, But, there's still a low frequency hum coming from the speaker, constantly. The tech guy (greg) said he cleaned out the dust, and did something to the power supply (capacitors).

Anyone here own a tube amp? Is it common to have a 'hum' coming from speaker?
It's slightly better than before, but it's noticable in my recordings, do you guys normally 'gate' these frequencies out or something?

 

[Lt. Bob]

got the amp back today from a tech who works next to our factory, and is not as noisy as before, But, there's still a low frequency hum coming from the speaker, constantly. The tech guy (greg) said he cleaned out the dust, and did something to the power supply (capacitors).

Anyone here own a tube amp? Is it common to have a 'hum' coming from speaker?
It's slightly better than before, but it's noticable in my recordings, do you guys normally 'gate' these frequencies out or something?

it's hard to know without hearing it but yes, a certain amount of noise is usually normal with most tube amps.

Is it noticable while you're actually playing guitar thru the amp during recording?
The sound of music should overpower the noise to where you can't really hear it over the guitar while actually playing. If it's loud enough that you can still hear the noise while playing then I wouldn't consider that normal.

 

[guitaristdan103]

it's hard to know without hearing it but yes, a certain amount of noise is usually normal with most tube amps.

Is it noticable while you're actually playing guitar thru the amp during recording?
The sound of music should overpower the noise to where you can't really hear it over the guitar while actually playing. If it's loud enough that you can still hear the noise while playing then I wouldn't consider that normal.

when im playing the guitar you cant hear it, but when theres a silent spot or where there no notes being played, but still recording, the hum is there.....probably only noticable to me lol. i'll try and post a sample of it sometime. thanks for your input anyways.

 

[ggunn]

when im playing the guitar you cant hear it, but when theres a silent spot or where there no notes being played, but still recording, the hum is there.....probably only noticable to me lol. i'll try and post a sample of it sometime. thanks for your input anyways.

Well, if you are using a DAW, simply go into your guitar tracks and insert silence in those places.

Every tube amp I have ever owned has produced at least a little bit of hum.

 

[Sonixx]

Is it common to have a 'hum' coming from speaker?

Fairly common, yes but it's an over generalization to assume because it's a tube amp it will hum.

There's different reasons such as power supply filtering is degraded or layout is poor and/or needs adjusting.

Does it hum just as loud with no input and the volume(s) turned down? Does the Hum level change with the Bass control?

Does Australia have 50 or 60Hz Power? Is the hum frequency twice your power frequency?

 

[guitaristdan103]

Well, if you are using a DAW, simply go into your guitar tracks and insert silence in those places.

Every tube amp I have ever owned has produced at least a little bit of hum.

It's a roland br 1600cd DAW. Yeah i'll probably just cut out those silent parts then.

Fairly common, yes but it's an over generalization to assume because it's a tube amp it will hum.

There's different reasons such as power supply filtering is degraded or layout is poor and/or needs adjusting.

Does it hum just as loud with no input and the volume(s) turned down? Does the Hum level change with the Bass control?

Does Australia have 50 or 60Hz Power? Is the hum frequency twice your power frequency?

nah it doesnt matter what volume level it's at, whether the bass is high or low, treble at full or whatever... its just got hum to it. The4 technician said that there's nothing else wrong with it, so i think it's good enough,

Australias frequency is 50hz i think, how can you test to see what frequency its at, what would that mean if it was exactly double, grounding problem?

thanks

 

[ggunn]

nah it doesnt matter what volume level it's at, whether the bass is high or low, treble at full or whatever... its just got hum to it. The4 technician said that there's nothing else wrong with it, so i think it's good enough,

Australias frequency is 50hz i think, how can you test to see what frequency its at, what would that mean if it was exactly double, grounding problem?

thanks

All I think it would establish is that the hum is coming from the AC line, but we're pretty sure of that already. One question I don't think was answered: does your amp have a two or three conductor AC plug? If it's only got two, then changing it to three (adding an earth ground pin) might make the amp hum less. It would certainly make it safer.

 

[Sonixx]

nah it doesnt matter what volume level it's at, whether the bass is high or low, treble at full or whatever... its just got hum to it. The4 technician said that there's nothing else wrong with it, so i think it's good enough,

then it's more than likely in the power section. too bad you have to live with it. you wrote here so it probably does bother you. since I have no clue of the skill level of your tech, I have nothing else to offer without putting it on the bench.

Australias frequency is 50hz i think, how can you test to see what frequency its at, what would that mean if it was exactly double, grounding problem?

thanks

Double because the rectifier flips the negative peak to positive and you will have a 100Hz (double your power frequency) rectified signal that is filtered to DC

 

[guitaristdan103]

All I think it would establish is that the hum is coming from the AC line, but we're pretty sure of that already. One question I don't think was answered: does your amp have a two or three conductor AC plug? If it's only got two, then changing it to three (adding an earth ground pin) might make the amp hum less. It would certainly make it safer.

it's got a three pin plug on it already

then it's more than likely in the power section. too bad you have to live with it. you wrote here so it probably does bother you. since I have no clue of the skill level of your tech, I have nothing else to offer without putting it on the bench.

Double because the rectifier flips the negative peak to positive and you will have a 100Hz (double your power frequency) rectified signal that is filtered to DC

ok, thanks mate, must be in the power section then, i don't know what else to do, the tech' looked at it and all is ok, so it probably is just how that amp is. Its the only valve amp made by roland btw. possibly broken wire, earth, maybe?