can a 50 watt amp put out 100 watts???

[Justin Thomas]

That's very tempting to use as a signature line...

Justin

[Chuck H]

That's very tempting to use as a signature line...

Justin

It might lose it's kick without the setup.

[mhuss]

Are we listening to continuous sine waves or musical signals that largely consist of transients and where crest factors can be moderately high?

If you're listening to current popular music, you're listening to (approximately) soft-clipped pink noise. Load any current hit into an app like Audacity and see what the waveform looks like. Like as not, it looks like a black horizontal bar instead of a waveform! Load it into a DAW with an app that measures crest factor, and you'll see low single digits.

Classical and jazz records are not like this, but who sells the most? There was a time (say, back when class-H amps first came out) when this argument carried some weight, but not in the 2010s.

[Chuck H]

And just to add... Many audio programs are apt to include some sort of very large, sustained tone for it's artistic affect. And now I'm recalling some threads started here about the time switch mode power supplies started making their way into instrument amps. Some bass players were having a hell of a time getting a satisfactory punch out of them.

[teemuk]

There's actually some pretty interesting discussion about thse kinds of topics at Talkbass.com amp section; some very talented amp designers hang around there.

Anyway, as far as I know, switch mode power supplies are not inherently "less punchy" since inherently they have built-in self-regulation and should theoretically outperform generic power supplies with inhently higher losses and no inherent self-regulation built in.

That is, theoretically.

I assume there are many SMPS designs out there that kick in to some sort of protection or current limiting mode if current draw remains escessive continuously. So, we are essentially again discussing same topic as with amps: how these things are designed, how the designs are eventually rated and in what terms. Just because its SMPs doesn't mean its inherently inferior. SMPS is pretty much improvement from the older stuff but there's nothing particularly new in "designing to certain price category". Sometimes designs must be "cheapened out" in order to make them competitive.

There's a different aspect to this discussion too: I recall at least one patent about designing in "sagging" characteristics to SMPS. There's a regulator in a SMPS, and while most employ a servo feedback loop to keep output voltage at constant fixed level there is by no means an absolute rule that the output voltage of a SMPS must remain fixed. In fact, you can make it track the audio signal dynamically just like any other regulator.

[Chuck H]

...there is by no means an absolute rule that the output voltage of a SMPS must remain fixed. In fact, you can make it track the audio signal dynamically just like any other regulator.

And this might reduce the onset of limiting by protection circuits, and so make a SMPS behave more like the older designs. If that were preferred by players.

I'm guessing the variable regulation would be done with something like a signal controlled MOSFET? I'm pretty much illiterate here, but I see this sort of thing discussed here often enough. I wonder though, how might such regulator circuit do with a control signal that moves in and out of clipping? As might be the case with a guitar amp. Maybe some with a bass amp too?

[TimmyP1955]

Measurements on some modern power amplifiers.

Comparative Performance - SpeakerPower

[teemuk]

If I recall, Fender and parsek (Markbass, etc.) had some patents (or pending patents) regarding more advanced ways to utilise switched mode power supplies in things like guitar amps.

Overall, there were some efficiency benefits from using higher frequencies and some other stuff releated to SMPS in general but to tell the truth, knowing rudimentary basics of operation excluded, all that high frequency + switching stuff related to both SMPS and switching amp classes goes way beyond my knowledge. I'm not the one who can in great detail explain, for example, how negative feedback loop of a self-regulating switched mode power supply works, but I do understand the concept that such loop doesn't have to restrict into use of "fixed" references but can have dynamic characteristics designed in. Engaging a protection / current limiting mode, for example, is probably following conceptually similar principles than, say, mimicking various "sag" characteristics of different kinds of power supplies. It's just a matter of application.

I'm also not the one to explain in great detail why operating power supplies is more efficient the higher their cycle rate is. But it is. Think of aviation applications; they use cycle rate of 400 Hz and save substantially in both size, weight and cost of transformers. Now let's pump that cycle rate ludicrously higher. That's modern SMPS. I think it's pretty clever idea all in all.

But as said, I'm complete n00b in knowing any detailed stuff about their operation / design than the conceptual level.

But I know there are members on this forum who know plenty about the topic. Let's hope they join in discussion.

[Chuck H]

I'm going to go off a little on this subject. Not the tech, I couldn't hold up that end. More the ideology of modern designs...

I know Peavey and Roland have done a little work in the arena of simulating tube amp sound with SS. Probably by simulating power and freq/impedance anomalies characteristic of tubes. And here we've started discussing how it's possible to control, with some detail, the specific characteristics of the most modern power supply designs. Maybe I'm an old fart, but doesn't it seem a shame that with all the new understanding of any real difference between tube and SS, old vs. new power supplies, the trend continues toward digital modeling OR uber gain tube 100+W metal monsters.?. After years of watching different ideas and some reasonable success WRT "simulating" tube tone it seems that most commercial amps that ever attempted it have only gone halfway there with what's possible. Which is sort of crazy to me when you consider that going all the way there would still be less expensive than a real tube amp. Well, excepting the R&D I suppose. It's true enough that I got into tube amp circuitry because I wanted better sounding amps. And since becoming familiar with the expense of producing and maintaining the circuits I've been heard to say that "If they ever make a SS amp that really sounds like a tube amp I'll buy it and never look back." I still think a SS amp that sounded like a tube amp, and not just mostly, but actually, would be an exciting development. Tastes are all relative, of course. "I" think tube amps sound better than solid state amps. Obviously and especially when clipping is involved. The possibility that in ten years "tone" will mean either an uber gain tube preamp (with almost none of that whole amp mojo) or the least bad digital simulator is disheartening for me. Especially when the technology to make a tube sounding SS amp is right here and now. Maybe the market demographic is too small for that kind of thing. You've got jazzers and blues men that want a "tube amp" period. And then you've got the uber gain metal guys that'll buy whatever their favorite player uses. And then you've got working class musicians that do fine anything versatile and reliable that doesn't sound straight up bad. That may be the nature of the market. With no reason to develop an amp that sounds (and feels) like a real tube amp at an affordable price.

[Gingertube]

I'll give you an analogy for PMPO (Peak Music Power Out).

In the day job I build airborne survey equipment using a pulsed laser.
The laser power output is approximately 10 Watts (Average Power).
However, each laser pulse has a peak power of 10 Million Watts but those laser pulses last for 5 nano seconds.

So do I have a 10 Watt laser or a 10 Million Watt laser? - Answer is YES

Cheers,
Ian

[Chuck H]

I'll give you an analogy for PMPO (Peak Music Power Out).

In the day job I build airborne survey equipment using a pulsed laser.
The laser power output is approximately 10 Watts (Average Power).
However, each laser pulse has a peak power of 10 Million Watts but those laser pulses last for 5 nano seconds.

So do I have a 10 Watt laser or a 10 Million Watt laser? - Answer is YES

Cheers,
Ian

What I want to know is... How come "I" don't have a 10 million watt laser Oh the things I might do.

[J M Fahey]

What I want to know is... How come "I" don't have a 10 million watt laser Oh the things I might do.

Oh, it would be great for collecting unpaid bills :

[Chuck H]

One of my favorite Bond film lines:

Bond) Do you expect me to talk?

GF) No Mr. Bond. I expect you to die.

[Amp Kat]

There's actually some pretty interesting discussion about thse kinds of topics at Talkbass.com amp section; some very talented amp designers hang around there.

Anyway, as far as I know, switch mode power supplies are not inherently "less punchy" since inherently they have built-in self-regulation and should theoretically outperform generic power supplies with inhently higher losses and no inherent self-regulation built in.

That is, theoretically.

I assume there are many SMPS designs out there that kick in to some sort of protection or current limiting mode if current draw remains escessive continuously. So, we are essentially again discussing same topic as with amps: how these things are designed, how the designs are eventually rated and in what terms. Just because its SMPs doesn't mean its inherently inferior. SMPS is pretty much improvement from the older stuff but there's nothing particularly new in "designing to certain price category". Sometimes designs must be "cheapened out" in order to make them competitive.

There's a different aspect to this discussion too: I recall at least one patent about designing in "sagging" characteristics to SMPS. There's a regulator in a SMPS, and while most employ a servo feedback loop to keep output voltage at constant fixed level there is by no means an absolute rule that the output voltage of a SMPS must remain fixed. In fact, you can make it track the audio signal dynamically just like any other regulator.

True but without monitoring current it's really hard to say what it's doing under load but I highly doubt it would sag as much as a linear supply. There could be some benefits in the preamp circuit though.