How does this sound? 2 speakers in series (now 16 ohms) another 2 in series (16 ohms) and parallel both pairs (back to 8 ohms). Each should share the 100W equally.

 

No audio power amplifier is 100% efficient. If it is electrically or thermally overloaded then it blows up or it protects itself by shutting down. Most IC audio power amplifiers protect themselves from abuse.

Class D comes pretty friggin close to 100%... some minor switching losses is about it.

 

A class-D amplifier output circuit is made small because it does not get too hot when it is not overloaded. Like any other amplifier, it has a rated minimum impedance load.

 

A class-D amplifier output circuit is made small because it does not get too hot when it is not overloaded. Like any other amplifier, it has a rated minimum impedance load.

The TS is not asking about another amplifier, but about how to connect the four speakers safely.

 

Series parallel. Power handing goes up x4, impedance stays the same as one speaker. Assuming all speakers are identical and uncoupled from each other.

 

can I use 4 25 watt speakers behind a 100 watt amp without damaging the voice coils? would they have to be wired a certain way?

Thanks everyone for all the replies! I have decided to go with a 12" speaker at 100 watts . the amp in question is a Rod Elliot guitar amp ,Elliot sound products. 100 watts into 4 ohm. Again thank you all. I certainly know now where to get answers.

 

So with 4 8m ohm speakers 4 ohms is not achievable, so you would get a bit less power and the speakers would be safe.

 

a bit less power and the speakers would be safe

it's not about heating up the speakers but to filter the sound so that it sounds good even at moderate volume levels
. . . if you start hearing distortion --or-- notice (hear) the relative spectral power change in between instruments --and/or-- in single instrument spectral components (although your speakers can handle more without breaking) it's a good point to draw the volume a bit back from and accept the "linear" region of your speakers end there . . .
my settings : not a standard - must be matched to combination of devices and the source sound
2.0 Speaker system Defender AURORA M35 36W, wooden box (treble ~90% bass ~60%) & i don't think the boom box would much add up to this

 

Any guitar amplifier that is even close to a "HiFi" amplifier is very rare. Neither flat frequency response nor low distortion are goals that I have seen. It is like comparing fork-lift trucks and speed boats. The main similarity is that they are both audio frequency amplifiers.

 

Rod Elliot has many amplifier designs on his website but none is called a "100W into 4 ohms guitar" amplifier.
100W into 4 ohms is 20V RMS which is 56.6V p-p. Then a power supply of about +/-35V is needed.
Into 8 ohms the power is about 60W, but you might not hear that it is less than 100W.

 

Incorrect operation? The amplifier and speakers are for an electric guitar. They want the sound to be BAAAAD, really BAD.
Tons of awful distortion and maybe the boomy effect caused by speakers in series.

Most rock groups replace the vacuum tubes for each gig, because they are abused badly.

Yes...but the distortion isn’t created by the speakers and amp. It’s created by effect units..

eT

 

but none is called a "100W into 4 ohms guitar" amplifier.

? that sounds close enough 100W Guitar Amplifier Mk II "The amp is rated at 100W into a 4 Ohms load, as this is typical of a 'combo' type amp with two 8 Ohm speakers in parallel."

 

Yes...but the distortion isn’t created by the speakers and amp. It’s created by effect units..

eT

The distortion is an attempt to reproduce the distortion produced by tube amps back in the sixties, among other things also the overdriven transistor amps. And if some of the ditortion is from the amp then who cares. These are not audiophiles with golden ears who can clearly hear 0.001% harmonic distortion on orchestra music.

 

Yes...but the distortion isn’t created by the speakers and amp. It’s created by effect units..
eT

Electric geetar amplifiers are always clipping like crazy because the effects produce so much distortion that the player cannot hear when the amplifier is clipping or not.

 

typical waveform for the 60's fuzz face was built on a germanium transistor: assymetrical hard clipping to add overtones and then compression to induce long drawn out tones... think of Pink Floyd solo from Comfortably Numb... and Hendrix. Distortion is color way beyond tube distortion which is very mild.

 

Electric guitar players are deafened by the loudness and high levels of high frequency "fuzz" and "overdrive" distortion which is why they use too much of it since they can barely hear it.
At my age of 74, I cannot hear the smoke detector or telephone ringing in my bedroom due to normal-for-my-age high frequency hearing loss and electric guitars sound pretty good until I put my hearing aids on, then I can hear that there is way too much distortion.

 

Electric guitar players are deafened by the loudness and high levels of high frequency "fuzz" and "overdrive" distortion which is why they use too much of it since they can barely hear it.
At my age of 74, I cannot hear the smoke detector or telephone ringing in my bedroom due to normal-for-my-age high frequency hearing loss and electric guitars sound pretty good until I put my hearing aids on, then I can hear that there is way too much distortion.

"Way too much distortion?" That is like saying an AAA class fuel dragster is accelerating too fast.

 

Distortion is color palate as much as intentional phasing and other tricks.... some of the best pre-amps out there add coloration to the signal. I worked in classical and rock pro-audio. Classical is pretty boring to record and produce. The engineering aspect in rock goes up exponentially. It's fun to gate a low frequency tone using a peak detector from a kick drum then put an envelope... So many cool things you can do to "enhance" sound... then put it through a couple 1176 limiters to really put some edge on it... anyhow, fun stuff. Tube stuff is nice but the the noise floor can get quite high and the effect is very subtle.

 

The distortion is an attempt to reproduce the distortion produced by tube amps back in the sixties, among other things also the overdriven transistor amps. And if some of the ditortion is from the amp then who cares. These are not audiophiles with golden ears who can clearly hear 0.001% harmonic distortion on orchestra music.

Guitarist care about amp distortion. Just not as much as an audiophile. And most do not play using distortion 100% of the time. That’s why they use effect units.

eT

 

The distortion produced by the effects unit masks amplifier overload distortion. The musicians are deaf to the many high frequency harmonics produced by the amplifier's clipping. At a gig, the musicians could not see the clipping indicator on the amplifier but I saw it blinking all the time.