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

[rabies]

is any of the following really true?? that would mean my marshall dual monobloc could potentially put out 400 watts!

Most amps are rated at the onset of clipping, and when pushed into distortion (or as we like to say: Cranked!) can put out twice that rated power. So a 100-watt amp will put out up to 200 watts when wound up.

Take a 50-watt JMP Marshall for example. 50 watts, right? But its already putting out well over that by the time you even get the volume halfway up.

So what's the first we do when we hook up an attenuator? Dime it, of course, which means the attenuator better be rated double the amp.

And it does get confusing. The Richter says "100 Watts Max" on the back, and they mean an amp capable of producing 100 watts of power, which is just about any 50-watt amp out there.

http://forum.grailtone.com/viewtopic.php?f=4&t=31631

[stokes]

Depends on the amp.Most amps are rated as "50 watts RMS".This means it is rated to put out 50 "clean" watts.As stated in the quote,when cranked will put out roughly 2X that.I have a 100 watt Showman that peaks at about 180 or so.For the record,I've not measured any amp that actually put out twice the rated wattage,not to say it isnt possible,just have'nt had the occasion to see more than the mentioned Showman.

[Robert M. Martinelli]

I agree there's a lot of confusing info around....
I'd say if you really need to measure a certain amp's output power, the conditions should be always stated, and, possibly, standardized....
( RMS, not peak to peak, on a dummy load; though not a "real world" method, this method is the most widely used and the closest to the "truth" ).

This said, I think the actual power it's not so important after all....doubling the power only increases the sound level by a sheer +3dB ( the accepted standard for the lowest variation in sound intensity the human ear can perceive ).

Does it make sense to stress tubes operating them at ( or beyond ) their limits to get a mere +3dB ? In my humble opinion...absolutely not.

You could get the same loudness increase by simply using a speaker with an efficiency of 96 dB/1W/1m instead a speaker having an efficiency of 93dB/1W/1m, all the other factors being the same ( including power consumption )

Hope this helps

Best regards

Bob

[rabies]

You could get the same loudness increase by simply using a speaker with an efficiency of 96 dB/1W/1m instead a speaker having an efficiency of 93dB/1W/1m, all the other factors being the same ( including power consumption )

Hope this helps

Best regards

Bob

sorry but what does 96 db/1W/1m mean? decibels, watt, m=?

[Chris / CMW amps]

sorry but what does 96 db/1W/1m mean? decibels, watt, m=?

at 1 metre (about 3 ft.) distance

if you put 1 Watt into that speaker and do measure the sound-pressure at that distance you'll get 96 dBs.

[loudthud]

If we connect a 20V DC power supply to an 8 ohm resistor, the resistor is said to dissipate 50W. If an amp near clipping can produce a sine wave (we have to allow some distortion) of sufficient voltage (called 20V RMS) to cause the resistor to dissipate 50W, we can say the amp is rated at 50W. The same amp can produce a Square Wave that will cause the resistive load to dissipate roughly 100W (if it's power supply can handle it). The 0.707 RMS conversion rule only applies to pure sine waves. When a sine wave and a square wave have the same peak voltage, the square wave has more area "under the curve" and thus is more efficient at producing heat (measured in watts) than a sine wave.

[booj]

When an amp is "pushed hard" the clipping can be so bad that the output turns into a square wave. It's the most you can get and is about 1.4 x the clean power. So a 100 watt amp can put out 140 watts of speaker destroying power, but that's a different subject.

[teemuk]

When an amp is "pushed hard" the clipping can be so bad that the output turns into a square wave. It's the most you can get and is about 1.4 x the clean power. So a 100 watt amp can put out 140 watts of speaker destroying power, but that's a different subject.

Actually, the peak value derived from average power rating is approximately 2x. An amp rated for 100W at the onset of clipping and at low % of THD will produce about 200 watts of peak power, and for square waves the average ratio is same as the peak power.

And that is for amps that "brick wall" clip after average rating of power is achieved. Amps that "soft clip" may easily pump out even more output power. But of course with plenty of distortion in the output signal.

..Oh, your math (if done properly) would tell that as well:
Peak voltage of sine wave is RMS value times 1.414. So is peak current. Multiply them (for power, which is V*I) we get "2". So if average power (derived from V RMS or I RMS) is, say, 1W, the peak is 2W.

But since this rating is derived with very high % of THD (as said, we're talking about sine waves clipped to square waves) it's more or less useless...

At best you can estimate the peak power pushing the speaker load, but since the speaker power rating is merely for thermal power dissipation - excluding other vital details like power vs. cone excursion - there's really not too much benefit from that either. In the end you still need to -listen- if you're a) too loud b) pushing way too much power for the speaker load to stay in the reliable zone.


Edit: Wow, what "Zombie thread"! Well, posted anyway so...

[Pedro Vecino]

This said, I think the actual power it's not so important after all....doubling the power only increases the sound level by a sheer +3dB ( the accepted standard for the lowest variation in sound intensity the human ear can perceive ).

Did this statement is referred to the full frequency response of an instrument? Raise or lower a program 3 dB. to identify a volume change?
Or it´s also applicable to a part of a program (for example: the area between 200 and 500Hz)?
I have no posibility to measure decibels, but my music equipment handle progressive steps of +2/-2 dB. in the eq. (bass and treble separately) and when I apply a step up in the treble starting from 0dB. many times I wish it were just of 1dB because 2dB. interval is excessive.
It´s difficult to understand that distinguishing 1 dB. with the equalization are 3dB. necessary to observe a change in the volume of a complete program. I mention this as curiosity and from my ignorance of that statement.

[tedmich]

depends how you measure it!

[J M Fahey]

FWIW all these new fancy switching power amp switching supply digital waveform pre processing etc. "12kW in a 1 U rack" ampos use a "new" spec called EIAJ , apparently EIA (which is a reasonably serious institution) but the Japan branch, which has looser standards.

And yes, it's somewhat similar to what tedmich posted above
FWIW none of those amps can put out continuous power because their supplies protection turn them off
Typically max continuous power is 2kW or thereabouts.

Legalized PMPO?

[nashvillebill]

I have difficulty with the ratings on the new switching amps too. I still can't see how an amp that pulls at most 2.4kW from a nominal 120 volt, 20 amp circuit...can be rated at 5kW (or more) output???

I guess I can claim my car will do 200 mph too--if it were thrown with a catapult.

[g1]

If you can make 5KW from a 2.4KW outlet, you should be able to put 60hz into the input and get into the power generation business.

[Leo_Gnardo]

FWIW all these new fancy switching power amp switching supply digital waveform pre processing etc. "12kW in a 1 U rack" ampos use a "new" spec called EIAJ , apparently EIA (which is a reasonably serious institution) but the Japan branch, which has looser standards.

Yes I've seen those amps, in the fine print 12kW pulse for 1 cycle at 1000Hz, so what's that good for? (The excess "surprise' energy stored in the magnetic fields of those golf-ball size transformers, are you kidding me?) Do these amp manufacturers have some sort of advance idea what "music" will sound like in the future? If it's going to be a series of 1 KHz single pulses, I'm stocking up on earplugs NOW.

Then there's the guy you were trying to help with that goofy kit a couple weeks ago, turns 50W amp into 100W. My conclusion: if it were all that and a bag of chips, then WHY isn't everybody doing it? Good luck to him. I'm working on a circuit that will turn $50 into $100, now that's a lot more useful.

[Jazz P Bass]

I worked on a boom box that put out some pretty impressive volume.
Most of it was bass due to the speaker enclosures.

It had a label that stated: '300 Watts'.

Smirk.

The amp pulled 28 watts max from the mains.

Kirk:" Scottie, I need more power!".
Scottie:" "I've given it all she's got, Cap'n."
Aah: dilithium crystals