Can I operate D-Class amplifier with disconnected power stage?

[agedhorse]

The studio 40 has DSP in the preamp.

 

[mmon77]

I meant to quote this:



How else are we going to have people interested in engineering and electronics if we discourage folks from tinkering or advise them to just buy another preamp. If I told my son that he just needs to be finance a new car rather than attempting to replace the engine by himself, he would not have acquired new skills. If the OP contacted some of our members who actually have the knowledge it will be more productive than everyone else piling on the bandwagon of discouragement or even ridicule at times.

If you try and fail to replace the engine in your car, short of maybe dropping it on yourself, in the worst case you may end up with a car that doesn't work. Go poking around in an electrical device that is powered by line voltage, and you might die. There is a difference.

No one is saying not to do it at all, but it is obvious to those of us who have some electrical knowledge when someone else is misinformed, uninformed, doesn't understand the risks, etc. An example would be saying that an unplugged device is safe to take apart and play with. That is why, at least I personally, don't encourage some people. To do so would be irresponsible.

 

[sokolasty]

1. The Rumble 40(V3) does not use a class D power amp, therefore the OP's original assumption is simply incorrect.

This is pretty much of a surprise for me. As @seamonkey mentioned, Fender writes D-Class

2. The power amp in the Rumble 40 can be safely operated without a speaker connected.

Thank you for this information

3. The part that the OP is assuming is the power amp is actually the switchmode power supply and not the power amplifier.

Besed on the above, the OP does not have the knowledge or understanding to be modifying this amp IMO.

This is right and this why I asked

BTW: picture isn't wrong, it's actual amp I have. This is Studio 40, not 40. I guess they look different
Perhaps this brings questions

 

[Lava]

Yeehaw!

 

[BlueTalon]

In my previous life as a power plant/drydock mechanic, I used to work with large steam, compressed air and water lines. I knew what they could do to me if I didn't respect them, but they usually would give me a little warning before disaster struck if something wasn't right. I also worked with electricians, many of whom told me about close calls they had had, because electricity, unlike steam, compressed air and water, doesn't usually warn you before it strikes.

Watch your butt, or you won't have one.

That reminds me of a prank I pulled when I was in the Navy. I was an engineer on my ship, so I rarely had reason to go up to the sonar room, but for whatever reason I was up there. I stepped through the hatch, and saw one of the sonar techs working on a pipe. He was a little guy, and the pipe he was working on was up in the corner of the compartment amongst a bunch of other pipes. He didn't have good leverage, so he was struggling -- and as luck would have it, he was facing away from me. I was going to say something to him, but I thought I might startle him, so I just stood there for a minute in silence. Then I had an evil thought.

I drew in a deep breath, and started slowly letting it out, hissing through my teeth, gradually getting louder. He struggled to urgently turn around so see what was happening, what was leaking and where, and then he saw me and about crapped himself. He had a pretty good laugh about it, but not until a few minutes after he managed to get his heart back into his chest.

 

[Tassieviking]

Arc flash injury only hurts while you are conscious. You are very, very fortunate to have survived without even worse injuries imo.

I was very lucky indeed, another electrician had placed a chart recorder in the cabinet earlier and he turned it on even though it was not measuring anything.
The chart paper was conductive and when I brought the second recorder to the cabinet and opened the door the paper moved and shorted the incoming 400mm cables in the terminal block, it melted 3 x 400mm cables and lugs clean off.
We never left those recorders in the cabinets when we were using them but the other electrician was in a hurry to get to the pub after work and did not think clearly.
We got better chart recorder a year later for work, it was in the 1990's and I was working as an industrial maintenance electrician back then. 95% of work was done on live equipment of some sort as the plant was running around the clock.
If things did not go wrong I would never have had that job, and we would have no ambulances or fire brigades and doctors would only deliver babies.

 

[40Hz]

I meant to quote this:



How else are we going to have people interested in engineering and electronics if we discourage folks from tinkering or advise them to just buy another preamp. If I told my son that he just needs to be finance a new car rather than attempting to replace the engine by himself, he would not have acquired new skills. If the OP contacted some of our members who actually have the knowledge it will be more productive than everyone else piling on the bandwagon of discouragement or even ridicule at times.

When dealing with anything that has an AC power cord it’s almost never advisable to “tinker” unless you have some background in what you’re doing and some basic understanding of what you’re “tinkering” with.

There’s also a difference between experimenting, which implies you’re not proceeding blindly, and tinkering or ditzing around with something just to see what happens and maybe figure out how it works assuming nothing gets fried first.
The ability to read a schematic and some degree of education in electronics are all you’d need to analyze and intelligently experiment with virtually any circuit. And while there is an element of art to instrument amplifier design, the theory and basics of audio amplifiers are well documented and readily available for study. So tinkering is an incredibly inefficient approach to learning about amplifiers or repurposing one in this particular scenario.

Or so I think anyway.