Question about W/P/C

[Johnny Vinyl]

In the specifications it says that my Marantz PM-KI-Pearl Integrated Amplifier has a rated output of 90 w/p/c into 8 ohms or 140w/p/c into 4 ohms. In Michael Fremer's 2010 review of this IA it says and I quote below:

Ishiwata claims that the Pearl's power ratings are conservative, and that it delivers a linear 110Wpc into 8 ohms or 180Wpc into 4 ohms.

Why rate this IA officially at 90w/pc/ when it is clearly capable of more?
Is there is specific rationale for doing so?

MF's review

[mep]

Under promise and over deliver.

[Johnny Vinyl]

Pretty standard line, but not sure if that's quite it.

[Alrainbow]

Many companies under rate products that's good
also some over rate as in same rating but peak and not RMS
many years ago Amps were made with a peak to peak rating meaning peak from each side of the sign wave so 100 is now 200 but really 100x .707 = 70 RMS
GLAD it measured more but how good it sounds really matters more lol

[Joe Pittman]

You can never have enough power in my opinion however, the first watt is the most important. The perceived power of the amplifier is directly related to the impedance of the loudspeakers. Ultra low impedance dips in the frequency band can suck the power supply dry. The best amps are load invariant, doubling down in power with each doubling of impedance.

[tom_hankins]

Damping factor plays a big role too.

[Alrainbow]

Do clads D Amps also have this doubling feature
my older Aragon's mono amos do my speakrkers dip to just below 2 ohms as well.
Maybe a post for another thread is pure class a and a/b
as most have in solid state. I have read that the first few watts on most are class a amd sound better and some claim they can hear when the bios changes to class a/b or b as some call it.
Shiuid I post another thread on this ?

[jonathanb]

My class D Merrill Thor Amps are 200 w/p/c at 8 ohms and 400 at 4 ohms.

[Rob]

My class D Merrill Thor Amps are 200 w/p/c at 8 ohms and 400 at 4 ohms.

what's the rated output at 2 ohms and do the amps like it

[jonathanb]

I've no idea as 2 ohm spec is not listed but since my speakers are Evolution Acoustic MicroOnes--nominally 6 ohm--I've had no issues.

[mep]

My Krell KSA-250 that I used to own was good down to .5 ohms.

[Alrainbow]

Yes one of things krells did well. I don't remenr what model krells I had years ago they were two large boxes for each c,ahnnel a d meter in the middle black . Truth is I like my cheap Aragone just as much perhaps a bit better on the highend . Low end has its own amps each side

[atmasphere]

You can never have enough power in my opinion however, the first watt is the most important. The perceived power of the amplifier is directly related to the impedance of the loudspeakers. Ultra low impedance dips in the frequency band can suck the power supply dry. The best amps are load invariant, doubling down in power with each doubling of impedance.

I agree with the first sentence. The remaining sentences are false.

2nd sentence: perceived power has a lot more to do with distortion than the impedance of the speaker! If the amp is making higher ordered harmonic distortion, it will be perceived as louder and therefore more powerful. Its very common for a small amp to sound loud while a much more powerful amp with less distortion does not seem to sound as loud even though its actually louder.

3rd: Ultra low impedance likely does not affect the power supply all that much. It affects the output section of the amp quite a lot!

4th: this is like saying that only solid state amps are the best, and at the very least the jury is still out on that one. You don't have to know anything technical to understand this, all you have to understand is that tubes (which can't double power like that) are still very much around despite being declared 'obsolete' 70 years ago. If that were really true, tubes would be long-gone. But they are still very much with us and the tubes/transistors debate is older than the Internet. This suggests that the best amplifier (whatever 'best' must mean) could well be a tube amp that does not double power. In fact the doubling power thing is a pretty weak argument- how about how it sounds? That might be more important...

[MylesBAstor]

I agree with the first sentence. The remaining sentences are false.

2nd sentence: perceived power has a lot more to do with distortion than the impedance of the speaker! If the amp is making higher ordered harmonic distortion, it will be perceived as louder and therefore more powerful. Its very common for a small amp to sound loud while a much more powerful amp with less distortion does not seem to sound as loud even though its actually louder.

3rd: Ultra low impedance likely does not affect the power supply all that much. It affects the output section of the amp quite a lot!

4th: this is like saying that only solid state amps are the best, and at the very least the jury is still out on that one. You don't have to know anything technical to understand this, all you have to understand is that tubes (which can't double power like that) are still very much around despite being declared 'obsolete' 70 years ago. If that were really true, tubes would be long-gone. But they are still very much with us and the tubes/transistors debate is older than the Internet. This suggests that the best amplifier (whatever 'best' must mean) could well be a tube amp that does not double power. In fact the doubling power thing is a pretty weak argument- how about how it sounds? That might be more important...

How much of why we like tubes is due to the technologies ability to swing voltages?

[atmasphere]

^^ I don't think that has much to do with it.

As far as I can tell, its all about distortion. All amps distort and if they make higher ordered (and especially odd ordered) harmonics they simply aren't going to sound as pleasant. Many tube amps (not all!) make a bit of the 2nd harmonic which gives the amp a lush quality. While this is fun to listen to, its not neutral by any means. Many solid state amps are considered neutral as they don't make the lower ordered harmonics. But they do make the higher orders, which the ear interprets as brightness and hardness. That's not neutral either although many audiophiles give that a pass.

Back in the 1970s, Sony introduced the VFET (also known as Static Induction Transistor or SIT). These had triode linearity curves and more importantly, soft clipping. If Sony had continued down this road (instead of their usual MO which is to shoot themselves in the foot: Elcasette, Beta, minidisk...) we might have been able to leave tubes behind. But they didn't (for example the SITs were power devices but there really weren't any driver or voltage amplifier examples) and that's that. SITs don't handle a lot of voltage; despite that they do sound really good. Nelson Pass has a thread on DIYAudio with a revamped circuit using SITs. Sounds like most of the devices he obtained are sold out; to his credit Nelson also had a semiconductor house make some SITs for him but the house folded. IMO this is an area that is at the leading edge of audio (unless Class D somehow brings home on the promise...).

The funny thing is tubes can be really linear and so should not be making that much in the way of distortion. But they often do, simply due to topography of the circuit in which they reside. We avoided the typical 2nd harmonic thing simply by designing our amps to be fully differential- which incidentally is a common trait in solid state designs. Back in the 1970s Sunn (a guitar amp manufacturer) built a series of solid state amps that were renowned for their lush character. These amps used FETs in the preamp operating single-ended and zero feedback; the power amp section was single-ended right to the output transistors where are rather substantial transformer did the conversion from single-ended to push pull. So these amps make a lot of lower ordered harmonics much like tube amps (but still had the solid state harsh clipping otherwise). As long as you didn't drive them too hard they gave a lot to tube guitar amps a run for the money.

So topology and its effect on distortion plays a role as well has the characteristics of the devices themselves. Like you might expect, its not any one thing.

[MylesBAstor]

^^ I don't think that has much to do with it.

As far as I can tell, its all about distortion. All amps distort and if they make higher ordered (and especially odd ordered) harmonics they simply aren't going to sound as pleasant. Many tube amps (not all!) make a bit of the 2nd harmonic which gives the amp a lush quality. While this is fun to listen to, its not neutral by any means. Many solid state amps are considered neutral as they don't make the lower ordered harmonics. But they do make the higher orders, which the ear interprets as brightness and hardness. That's not neutral either although many audiophiles give that a pass.

Back in the 1970s, Sony introduced the VFET (also known as Static Induction Transistor or SIT). These had triode linearity curves and more importantly, soft clipping. If Sony had continued down this road (instead of their usual MO which is to shoot themselves in the foot: Elcasette, Beta, minidisk...) we might have been able to leave tubes behind. But they didn't (for example the SITs were power devices but there really weren't any driver or voltage amplifier examples) and that's that. SITs don't handle a lot of voltage; despite that they do sound really good. Nelson Pass has a thread on DIYAudio with a revamped circuit using SITs. Sounds like most of the devices he obtained are sold out; to his credit Nelson also had a semiconductor house make some SITs for him but the house folded. IMO this is an area that is at the leading edge of audio (unless Class D somehow brings home on the promise...).

The funny thing is tubes can be really linear and so should not be making that much in the way of distortion. But they often do, simply due to topography of the circuit in which they reside. We avoided the typical 2nd harmonic thing simply by designing our amps to be fully differential- which incidentally is a common trait in solid state designs. Back in the 1970s Sunn (a guitar amp manufacturer) built a series of solid state amps that were renowned for their lush character. These amps used FETs in the preamp operating single-ended and zero feedback; the power amp section was single-ended right to the output transistors where are rather substantial transformer did the conversion from single-ended to push pull. So these amps make a lot of lower ordered harmonics much like tube amps (but still had the solid state harsh clipping otherwise). As long as you didn't drive them too hard they gave a lot to tube guitar amps a run for the money.

So topology and its effect on distortion plays a role as well has the characteristics of the devices themselves. Like you might expect, its not any one thing.

Yes Sony has shown at a couple of shows lately the V-Fet amplifiers driving their speakers. I want to say there are two or three pairs of these amplifiers using V-Fets in existence. AFAIK, Nelson had the last of the V-Fets and they have officially gone the way of the dinosaur.

[Alrainbow]

Atmosphere may I ask what Amos you make ?
preamp , Amps , headphone or speakers.