Amp Noise Problems!

[Ghostman]

That's why every studio, touring show, legit venue, professional sound system, etc. all have power conditioners. It's not snake oil.

But there is a limit to how much they can fix the issue. But power conditioners should be used in every single setup. Period.

Glad the Jet City is working out for you Chromeboy! I'm going to check out that same head at a local GC this weekend. Never played through one and I'm curious.

 

[EndGame00]

Aluminum chassis is bad, mmmkay?

 

[chromeboy]

Hey guys, I got the amp noise down to a very reasonable level. Now I have a question. With my guitar plugged in the normal hiss I get now seems to cut in and out but when I play I do not notice any change in volume and doesn't seem to cut out when playing.
Is this a sign of maybe a bad tube ? I mean the tubes are chinese tubes and even the guy at jet city said that changing out the tubes to better ones could help with the noise. So what do you think? My head is new only about month old. Should it go back for service ?
This is my second head and I love the way it sounds. I don't want to get rid of it.

 

[ampmadscientist]

That's why every studio, touring show, legit venue, professional sound system, etc. all have power conditioners. It's not snake oil.

But there is a limit to how much they can fix the issue. But power conditioners should be used in every single setup. Period.

Glad the Jet City is working out for you Chromeboy! I'm going to check out that same head at a local GC this weekend. Never played through one and I'm curious.

You do not need a power conditioner.

If the electricity is bad, it should be fixed correctly - because power conditioner does not fix bad wiring, or bad grounding, etc...
If an unsafe condition exists, the power conditioner does not fix it.

People who tell you this:
"...power conditioners should be used in every single setup. Period."

are playing on your fears...and are not what you could call "experts."

But I'm sure it does quite a lot...for the sales of power conditioners.

"...But there is a limit to how much they can fix the issue..."

That's the point: they do not fix "any" issue.
Electricians fix electrical issues...not power conditioners.
That's why we have "electrical codes."
If your electricity is bad, get it fixed the right way.

"That's why every studio, touring show, legit venue, professional sound system, etc. all have power conditioners. It's not snake oil."

Every studio I have worked in...every touring show, every legit venue, professional sound system..etc...I have worked on:
DID NOT have a power conditioner.
Nor did they need one.

I have seen the "most" severe power surge problems imaginable....
(12,000 volts leaking into a building...)
But a conditioner would do absolutely nothing to solve that.

This is real "power conditioning."
It takes bad power...and RE-generates it...from scratch.
(generates a completely new sine wave.)
For a venue that uses 100-200 KW (sound system and lighting) it's going to cost over $20,000, just for a "basic" set-up.

I would know this: because I have installed it myself.

That's what professionals REALLY use....it's called: "re-generation."
You cannot buy that at a music store....Nor does it fit...in a 19 inch rack.

 

[ampmadscientist]

Aluminum chassis is bad, mmmkay?

Aluminum chassis can be used:
If the special precautions for grounding aluminum are followed.

A. The chassis cannot be used as a current path. (cathodes of power tubes do not use the chassis as a circuit path, etc...) Circuit paths are hard-wired instead.

B. Dissimilar metals cannot be used to attach ground to the aluminum chassis. (oxide must be prevented from forming between aluminum chassis and copper / steel ground conductors)

C. This is a code requirement, it's the law. The codes were created to prevent injuries.

But: this has nothing to do with the circuit / layout noise in a tube amp.
Noise : comes from several sources, and adds together.

 

[Ghostman]

So much wrong in these two posts.... I can't even begin.

Moving on...

 

[chromeboy]

Well ok, if you must be right. I have worked on a few tours and they ALWAYS used them but hey what do I know? Was only looking for some advice. Not an argument. So we can just leave it at that ok? Don't really appreciate all the caps.

 

[John DeVries]

There's a known problem with the JCAs where the tube heater PCB traces in the amp pick up noise. It results in a loud hum.

There's a link here about how to mod the amp for lower noise:
http://www.guitarampboard.com/forum/viewtopic.php?t=1615

I did the mod to my JCA50 head and it worked well. Before the mod I used an an MXR Noise Clamp with the amp's preamp section in the noise gate loop to reduce the noise.

Dead link, any other info or pics on this mod?

 

[ampmadscientist]

Dead link, any other info or pics on this mod?

You disconnect the filament power from the circuit board and run it with wires instead.
The wires hook to pins 4/5 and 9 on the preamp tube sockets V1 V2.
You route the wires away from the circuit board, avoiding pins 2 and 7 of the preamp tube sockets.
That will clean up the buzzing noise.
Another method is to use DC to power the filaments of the first 2 preamp tubes...

 

[Len]

Dead link, any other info or pics on this mod?

Here's the text from that other, now dead, forum:

From the factory, the amp is too noisy.

Removed all knobs, nuts, & washers on all the pots and jacks front and back, and the PCB screws that hold it to the stand-offs. Get the speaker/footswitch/fx-loop jacks loose and out of the way to make the flip possible, as well as snipping the zip ties...

The long traces that go from preamp tube to preamp tube are the target. They attach at the top and bottom of each socket...

While the PCB is flipped, took the opportunity to de-solder the blue/black jumper wire on the front of the PCB that goes from the power tubes to the preamp tubes (JP5-JP5).

I used a $7 spool of doorbell wire from Home Depot; 22g solid core. The wire itself is fine, but the insulation shrinks damn fast if you park the soldering iron on it. Gotta be quick with the heat...

First leg to put in is the jumper that goes from the power tubes to the preamp tubes (JP5). This is just old school bending/trimming/dry-fitting/repeat.

 

[ampmadscientist]

Here's the text from that other, now dead, forum:

From the factory, the amp is too noisy.

Removed all knobs, nuts, & washers on all the pots and jacks front and back, and the PCB screws that hold it to the stand-offs. Get the speaker/footswitch/fx-loop jacks loose and out of the way to make the flip possible, as well as snipping the zip ties...

The long traces that go from preamp tube to preamp tube are the target. They attach at the top and bottom of each socket...

While the PCB is flipped, took the opportunity to de-solder the blue/black jumper wire on the front of the PCB that goes from the power tubes to the preamp tubes (JP5-JP5).

I used a $7 spool of doorbell wire from Home Depot; 22g solid core. The wire itself is fine, but the insulation shrinks damn fast if you park the soldering iron on it. Gotta be quick with the heat...

First leg to put in is the jumper that goes from the power tubes to the preamp tubes (JP5). This is just old school bending/trimming/dry-fitting/repeat.

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Yeah I figured it was a filament noise issue (usually is).
And a power conditioner will not fix that in any way.

It's a really common problem in high gain amps....which is why many manufacturers use DC filaments instead.

 

[ampmadscientist]

Aluminum chassis is bad, mmmkay?

"Aluminum chassis is bad, mmmkay?"

Well in home made amps, the builders imagine it is OK.
But in amps that need to pass UL safety tests, certain precautions need to be followed.
After all we do have safety rules, even if some home made amps don't follow them...

Amps that are actually tested for safety:
Are required to follow the rules.
which means all appliances sold to the public need to comply with safety codes.
(even when you do not follow safety codes)

 

[ampmadscientist]

That's why every studio, touring show, legit venue, professional sound system, etc. all have power conditioners. It's not snake oil.

But there is a limit to how much they can fix the issue. But power conditioners should be used in every single setup. Period.

Glad the Jet City is working out for you Chromeboy! I'm going to check out that same head at a local GC this weekend. Never played through one and I'm curious.

"That's why every studio, touring show, legit venue, professional sound system, etc. all have power conditioners."

They don't all have them.
It's just something that people have been led to believe they need...but don't really need most of the time.
No, you don't need to use them in every single setup.
Most of the time you don't need anything like that.

Power conditioners are generally for: the very gullible.