New amp, dumb question

[lefty1979]

Just picked up a new to me WT800. Unpacked it, set it up and it sounds pretty great. One thing I noticed though, when I power it on the lights in my room flicker. Only briefly, and just when you power the amp up. I've had other amps plugged into the same wall jack (some as powerful as the WT800) and don't remember noticing the lights flickering before. Does the WT800 really pull that much juice?

 

[MattZilla]

I’ve lived some places where simply turning on the toaster flickers the lights, and others where friends and I can fire up multiple old tube amps and a PA and everything stays steady.

I think it has more to do with how your home is wired, the power grid your home is plugged into, and/or how many neighbours are already pushing the grid near its limit.

 

[Bonsist]

"Sathan was then cast out of Eden like a lightning bolt descended from heaven"
I think it's just that man. *shrugs*

On a serious note though, most times the fan or bathroom lights tuning off do the same thing with the entire studio flickering out just once before I'm back.

Makes a clicking sound in my monitors as well. Never knew why, just thought it was some grounding issue, but I'm not an electrician.

 

[Wasnex]

It's an old school amp with a big transformer and a fairly large bank of capacitors.

I couldn't say for sure, but I would not be surprised if there is a pretty large inrush of current when you first turn it on.

One of the bands I worked in years ago had a pair of medium sized Crest Power amps tied in with an Apogee speaker processor. I believe they were setup so you only had to turn on the speaker processor. In other words one switch turned on everything. But if you turned on both power amps at the same time it tended to pull the circuit breaker. So better to turn all three on and off separately.

 

[lefty1979]

It's an old school amp with a big transformer and a fairly large bank of capacitors.

View attachment 4216294

I couldn't say for sure, but I would not be surprised if there is a pretty large inrush of current when you first turn it on.

One of the bands I worked in years ago had a pair of medium sized Crest Power amps tied in with an Apogee speaker processor. I believe they were setup so you only had to turn on the speaker processor. In other words one switch turned on everything. But if you turned on both power amps at the same time it tended to pull the circuit breaker. So better to turn all three on and off separately.

Yeah, that’s pretty much what I was thinking. Big iron and big caps soaking up all that current.

 

[BasturdBlaster]

The 4 pro I used for many years did that same thing

 

[agedhorse]

That's not uncommon on older power amps, especially those with a toroidal transformer or switch mode power supply because the inrush current is very high because the core can partially saturate at power-up which reduces the primary inductance. (unlike an EI transformer that is naturally more current limited because of the additional primary copper and core structure)

Inrush current is now required to be managed through both the IEC safety regulations (both directly and indirectly via associated parts limits) and in some ways indirectly through the IEC EMC regulations that govern power supply harmonic limits.

Virtually all amps that need inrush current limiting (sometimes called soft start circuitry) now contain it, and for the most part this phenomenon that you are experiencing is becoming very rare. Every once in a while I will build a test bench power supply and forget to install the ICL components, on a big supply I can open a circuit breaker or supply primary fuse at power-up. Good reminder

 

[lefty1979]

That's not uncommon on older power amps, especially those with a toroidal transformer or switch mode power supply because the inrush current is very high because the core can partially saturate at power-up which reduces the primary inductance. (unlike an EI transformer that is naturally more current limited because of the additional primary copper and core structure)

Inrush current is now required to be managed through both the IEC safety regulations (both directly and indirectly via associated parts limits) and in some ways indirectly through the IEC EMC regulations that govern power supply harmonic limits.

Virtually all amps that need inrush current limiting (sometimes called soft start circuitry) now contain it, and for the most part this phenomenon that you are experiencing is becoming very rare. Every once in a while I will build a test bench power supply and forget to install the ICL components, on a big supply I can open a circuit breaker or supply primary fuse at power-up. Good reminder

Good to know. Pretty much follows what I was thinking and explains why I didn't see the same behavior with a Quilter Bass Block (same power, but modern class D. completely different design). Just wanted to make sure I wasn't going to burn the house down while practicing.

 

[Andy Marshman]

If it doesn't blow the amp's fuse, yes the current inrush is high at start up. If the fuse or breaker in your house doesn't open, no worries.