Does you Express pop when switching power levels?

[tmac]

Hi!

Does you Express amp pop when switching the power level while the amp is on (both power switches up)?

I have heard that this varies among the Lone Star amps (some pop, some dont), and would therefore like to know if this variation occurs also for the Express amps. The reason is that i'm thinking about making the power switching channel assignable like on the Lone Star, but first I need to understand if the Lone Star has any kind of muting circuit in the power amp.

My Express 5:25 makes a pop (the loudest being in the direction 5W -> 25W).

Only answer the poll if you already know if you amp makes such a pop or not. I.e. don't try it because of this poll, since I don't want to cause anyone to damage their amp by doing this while not on standby. I personally don't believe that it is damaging, but some do and I might be wrong. So its OK if nobody responds to the poll

 

[THE TUBENATOR]

tmac, I have not tried switching my 5:50 from 5W to 50W or 50 - 5 while the amp is on. But I'm sure it would make a popping sound if I did. When I ordered my amp and then again later when I received my amp the local Mesa dealer told me many, many times NEVER switch power level settings while the amp is on! He said it has to do with the 5W operating in pure class-A and the 50W operating in class A-B. He explained the entire power circuit is reconfigured therefore switching power modes while the amp is on in not good. I don't even do it on stand-by, I actually turn it completely off before I change power modes.

 

[screamingdaisy]

All of the amps that can go into pure class A mode pop when going in and out of that mode.... for instance, if you have 5w on channel 1 and 25w on channel 2 it'll pop when going back and forth. It's a compromise... either it pops a little bit, or they mute it and there's a momentary sound dropout whenever you switch channels.

Mesa mentions this in both the LSS and Mark V manuals. I haven't read the Express manual.

 

[MrMarkIII]

It's normal, it says so in the manuals, RTM.

 

[EtherealWidow]

tmac, I have not tried switching my 5:50 from 5W to 50W or 50 - 5 while the amp is on. But I'm sure it would make a popping sound if I did. When I ordered my amp and then again later when I received my amp the local Mesa dealer told me many, many times NEVER switch power level settings while the amp is on! He said it has to do with the 5W operating in pure class-A and the 50W operating in class A-B. He explained the entire power circuit is reconfigured therefore switching power modes while the amp is on in not good. I don't even do it on stand-by, I actually turn it completely off before I change power modes.

I know that the Mark V and the Express are totally different amps, but with the Mark V you can set every channel to different power tube operation. The power section has to be reconfigured every time. I imagine it couldn't be so harmful. That being said, I still do turn mine on standby just to be safe that I don't damage my mystical, mysterious amp.

 

[tmac]

I know that the Mark V and the Express are totally different amps, but with the Mark V you can set every channel to different power tube operation. The power section has to be reconfigured every time. I imagine it couldn't be so harmful. That being said, I still do turn mine on standby just to be safe that I don't damage my mystical, mysterious amp.

Yeah, that's why I wanted to determine if there is a difference between the Express on the one hand and e.g. the MarkV/LoneStar on the other. I did hear from one Lone Star user that the amp didn't pop at all, so that lead me to think about muting possibly going on in the Lone Star. But perhaps not.

For all I know it might be less "damaging" to switch the power levels on the Lone Star / Mark V due to some unknown minor circuit differences. I don't have the schematic, so its impossible for me to know. It could be just a case of wear on the switch/relay contacts or similar things.

So six out of six answers have confirmed the pop, which is as I expected.

 

[J.J]

From just general poking around with my Express, the power stage change between 5 and 25 watts ( and 25 to 5) is fairly rude, there appears to be no real attempt to do it nicely. I guess when we finally get a schematic we can tell for sure.

Probably the main cause of the poping is the switching off of one power tube. Each tube pulls about 20ma through its half of the transformer and turning one off suddenly will caue the transformer to "buck" as it is just seeing a rapid current change. A sharp rise on the output will result in the pop.

To stop the pop, the voltage and current change would need to be slowed down, or the output to the speaker muted momentarily. I'd probably try a short circuit on the output first becuase it is easy and will prevent any nasty voltage spikes in the transformer that may damage it.

 

[GoranS]

Of course it pops. You are not supposed to switch that way. The standby is your friend...

 

[Don]

Yep. Mine pops.

When I demoed one before I bought mine the salesman switched to standby before changing power levels.

 

[fridlmhupa]

here´s an interesting extraction of the manual from the new TA-15,
i think it has a similar Power section...

"You will experience more footswitching noise (pop) when switching between Channels when only one is set to the 5W power setting. This is due to the more radical voltage changes that occur when knocking the power section down to the 5W level from one of the higher power modes. (Using both Channels in 5W will not create excess noise as the voltage doesn’t change). May we suggest when configuring your Channels for live performance footswitching applications, try using the 15 and 25W power modes whenever possible as the voltage swings are not as great. This will provide the quietest footswitching performance.
Now that you have an overview of the TA-15, let’s get more specific "

I think it is anyway a good idea using the standby switch
greetz...

 

[Newysurfer]

Hi!

Does you Express amp pop when switching the power level while the amp is on (both power switches up)?

I have heard that this varies among the Lone Star amps (some pop, some dont), and would therefore like to know if this variation occurs also for the Express amps. The reason is that i'm thinking about making the power switching channel assignable like on the Lone Star, but first I need to understand if the Lone Star has any kind of muting circuit in the power amp.

My Express 5:25 makes a pop (the loudest being in the direction 5W -> 25W).

Only answer the poll if you already know if you amp makes such a pop or not. I.e. don't try it because of this poll, since I don't want to cause anyone to damage their amp by doing this while not on standby. I personally don't believe that it is damaging, but some do and I might be wrong. So its OK if nobody responds to the poll

hehhehehe of course the amp will pop if you switch power ratings when its turned fully on.
I'd be surprised if it didn't.
I've never tried it though and don't intend to.
I love the amp too much for that
Switching to standby first takes 5 seconds so I don't think its an issue at all :mrgreen:

 

[sulldog]

Yup mine pops.. I usually keep in it 5 watt mode. If i want to switch i put it in stand by mode first.