Why do loadboxes sometimes squeal and oscillate at loud volumes?

[Orvillain]

What's the reason for this?? Is it just a bog-standard feedback loop between the amp and inductor? Even when I use a 1:1 transformer in the signal path, it still does it.

It does it with loads of my amps. Not just one. I have the Suhr Reactive Load IR.

The moment I turn the amp down to "sensible" levels, it goes away.

 

[Devin]

Many amps will do this on their own if just dimed out in to the cab - are you diming the amp going in to the loadbox?

 

[Orvillain]

Many amps will do this on their own if just dimed out in to the cab - are you diming the amp going in to the loadbox?

I wouldn't say diming, no. Turning my Dual Recto up to about noon or 1 o'clock. Yes I understand it is loud. That's the entire point of the loadbox.

It doesn't do it when I connect it to a real cab.

 

[SillyOctpuss]

I'm interested in this too. I had this happen with my JVM into a two notes load box.

 

[fetishfrog]

This might explain it.

 

[Orvillain]

Cool, will check that in a minute, thanks!

 

[gearJunkie]

Magnetic field resonance induced oscillation

 

[laxu]

Other than the phenomenon described in Fryette's video, it could be just loading the amp in a different way from being connected to a cab directly.

The only way I can induce squeel with my Mesa Mark V is if I crank the treble and gain on the ch2 Mk 1 mode. That'll probably come down to preamp tubes too.

Connected to my Fryette PS-100 I don't find any of my amps to have that issue. When the amp is cranked and you are recording silently, you can hear your playing through the load though and that's normal.

You could try if moving the loadbox to a different spot helps. If it's e.g on top of the amp it might be too close to the amp's transformers.