Archon 50 high frequency hiss/noise

[TroyBaer]

Hi all,

I've recently noticed that my Archon 50 (SN 140556) has a pronounced high frequency noise or hiss. It's present on both channels, although it's far more noticable on the lead channel. Having a noise gate in front of the amp doesn't seem to help. It also seems to be invariant of whether the loop is engaged or not. I took the following FFT with an app on my phone last night with the clean channel dimed, all pedals off, and the volume of my guitar turned all the way down:

In particular, notice the spikes around 10kHz, 12kHz, and 20kHz.

(BTW, the signal chain for this is guitar -> Korg Pitch Black Tuner -> Mooer Rumble Drive -> Joyo American Dream -> Archon 50 -> PRS SE 2x12 cab on the clean channel with TC Mimiq, Corona, and Flashback pedals in the Archon's loop. All pedals were off and the loop disengaged.)

Is this the infamous Archon loop problem rearing its ugly head (mine is in about the right SN range...), a bad tube, or just bad building power?

 

[elvis]

I would recommend checking this with no pedals connected. If it gets noticeably better, add one pedal at a time to see how they affect noise.

How are you powering the pedals? Many power supplies are VERY noisy and may have ground loops.

The peaks are not a particular concern. They would not hiss, but would sound like tones if they were significant. Likely they are due to interference in your phone or in the room (cell phones have lots of EMI).

What is the difference between red and green?

 

[TroyBaer]

I would recommend checking this with no pedals connected. If it gets noticeably better, add one pedal at a time to see how they affect noise.

I'd meant to do that before rehearsal last night but ran out of time. I'll try it on Sunday if I get a chance. (This rig is currently located at my church, so I can only get at it once or twice a week without making special arrangements.)

How are you powering the pedals? Many power supplies are VERY noisy and may have ground loops.

It's a One-Spot with their 8-plug extender.

What is the difference between red and green?

AFAICT, the green is the instantaneous spectrum and the red is the maximum over the entire time the app is run. (The "Spectrum Analyze" app I have on my phone is, shall we say, a bit light on documentation.)

 

[elvis]

Interesting. I'm thinking that you may have a pedal or pedals that are sensitive to the switching noise from the One Spot. If your pedals are all True Bypass, you can set them in bypass and pull out the plug and see what you get.

 

[László]

One spots are pretty notorious power supplies in terms of adding noise of all kinds. Try unplugging your pedals and going straight in from the guitar.

The best power supplies have isolated, regulated outlets. In addition, most switching power supplies like the One Spot are inherently noisy and problematic. The exception is the new Strymon power stuff that utilizes a better design.

 

[Kred]

Most guitar speakers significantly roll off their high frequency response above 6-8KHz (a Celestion V30 is down 25dB by 7KHz), so you may be hearing the noise below 8KHz. Does the sound/spectrum change when you isolate the amp (input unplugged)? Try to determine which noise is inside versus outside the amp.

 

[TroyBaer]

I worked on this a little more before church this morning and narrowed it down to one of the three pedals in front of the amp. I brought my pedal board home to try to narrow it down further.

 

[TroyBaer]

This has taken a turn for the weird. - it turns out to be a combination of things. As far as I can tell, this is caused by having the TC Corona and Flashback on the same One-Spot 9V supply as the US Dream. Other pedal power supplies don't seem to do it.

I have a 9/12/18V pedal power supply with isolated outputs that I'm not using, so I foresee an pedalboard rewiring in my future...

 

[dkilpatrick]

This has taken a turn for the weird. - it turns out to be a combination of things. As far as I can tell, this is caused by having the TC Corona and Flashback on the same One-Spot 9V supply as the US Dream. Other pedal power supplies don't seem to do it.

I have a 9/12/18V pedal power supply with isolated outputs that I'm not using, so I foresee an pedalboard rewiring in my future...

You definitely need to have digital pedals isolated from analog pedals, if not then it causes a feedback in the power circuit.
Sounds like this might be what you are dealing with.

 

[Deleted member 5962]

It just hit me! This is a 50 watt Archon. The noise you are hearing is the little demons in the amp. They are very high pitched voices, but if you isolate them, you'll be able to hear them clearly. What they are saying is "Send me to DTR! Send me to DTR!"

Do you need my address?

 

[elvis]

Yup, power crosstalk is a pain. I only ever use isolated pedal power.

 

[Boogie]

Power problems are an elusive gremlin that you learn to despise. That's why so may players pay top dollar for high quality power supplies. It's one of those rare problems that you can simply throw money at and it disappears, forever. Which one? That will start a lively discussion.

 

[TroyBaer]

I put things back together last night, and while I still get some noise on the gain channel, it's clearly coming from the guitar (i.e. it goes away when I turn the guitar volume down), which was not the case before.

 

[László]

One Spots are noise magnets. They're not the right power supplies for grown-ups with good equipment.

 

[HANGAR18]

I hear an AM radio Christian station whenever I crank the volume up on most of my amps. Very Spinal Tap. I'm near the summit of one of the local famously tall hills and am apparently not using a shielded instrument cable.

 

[Deleted member 5962]

Amen!