Two Basic Amplifier Questions

[Henryk]

I'm embarrassed to ask such seemingly simple questions, but I can't seem to find the answer on my own!

1) An amplifier is rated for 60W @ 8ohm and 100W @ 4ohm. The speaker is rated as having 6ohm impedance.
Will the amplifier automatically run at 6ohm and provide power between 60 and 100W? Say, around 80W?

2) Say that a speaker is rated for handling between 100 and 200W RMS. Say that the listening volume is held constant at 70db.
Will a speaker powered by 200W, have any better sound quality than if powered by 100W, at the same 70db volume?
I'm aware that more power will enable higher volumes, but at the same volume does a speaker 'work' and sound better with more watts (within RMS)?

 

[fpitas]

1) Yes
2) It depends. A speaker will need a certain average power to output 70db: let's say it's 1 watt just for this discussion. Music can have 20dB peaks, so now you need 100W if you intend to faithfully recreate those.

In reality you probably don't need even 1 watt at 70dB.

 

[Henryk]

1) Yes
2) It depends. A speaker will need a certain average power to output 70db: let's say it's 1 watt just for this discussion. Music can have 20dB peaks, so now you need 100W if you intend to faithfully recreate those.

In reality you probably don't need even 1 watt at 70dB.

Ah, okay!
So let's say you provide enough wattage to hit your max listening volume, will applying more wattage have any impact on sound quality?
...or is wattage purely for hitting volume targets, and has no impact after that is met?

 

[fpitas]

Ah, okay!
So let's say you provide enough wattage to hit your max listening volume, will applying more wattage have any impact on sound quality?
...or is wattage purely for hitting volume targets, and has no impact after that is met?

It's mainly for peaks. Most people listen with maybe 0.5W average.

 

[suttondesign]

Ah, okay!
So let's say you provide enough wattage to hit your max listening volume, will applying more wattage have any impact on sound quality?
...or is wattage purely for hitting volume targets, and has no impact after that is met?

A well-behaved amp performs and sounds the same at all volume levels. Your ears do not have the same response at all volume levels, however. There are published curves which show your hearing response at different levels.

 

[Henryk]

It's mainly for peaks. Most people listen with maybe 0.5W average.

And if there is enough wattage to cover peaks? Will adding more wattage enhance sound quality?

What I'm getting at, is that I was under the assumption that speakers are 'happy' and work best with certain wattages.
I'm now wondering if that is true, if sound quality and wattage is related. Again, assuming enough power to meet required db levels.

 

[Doodski]

say you provide enough wattage to hit your max listening volume, will applying more wattage have any impact on sound quality?

More power to the speakers results in more dynamic peaks and better dynamic range.

 

[fpitas]

And if there is enough wattage to cover peaks? Will adding more wattage enhance sound quality?

What I'm getting at, is that I was under the assumption that speakers are 'happy' and work best with certain wattages.
I'm now wondering if that is true, if sound quality and wattage is related. Again, assuming enough power to meet required db levels.

Once you have enough for peaks, you're set. More available doesn't hurt, but like suttondesign said, good amps sound the same at all levels.

 

[peng]

I'm embarrassed to ask such seemingly simple questions, but I can't seem to find the answer on my own!

1) An amplifier is rated for 60W @ 8ohm and 100W @ 4ohm. The speaker is rated as having 6ohm impedance.
Will the amplifier automatically run at 6ohm and provide power between 60 and 100W? Say, around 80W?

2) Say that a speaker is rated for handling between 100 and 200W RMS. Say that the listening volume is held constant at 70db.
Will a speaker powered by 200W, have any better sound quality than if powered by 100W, at the same 70db volume?
I'm aware that more power will enable higher volumes, but at the same volume does a speaker 'work' and sound better with more watts (within RMS)?

1) No, amps don't run at 4,6,8 or any ohms as such, amps just amplifly the input signal voltage, and therefore output higher voltage that will deliver current to the speaker. The magnitude of the current will vary with the impedance of the speakers, and that in turn will vary with the music signal.

2) It depends, how much power your speakers need depend on several things, such as your distance, how loud you listen to, sensitivity and impedance of your speakers etc. If you do need 200 W maximum, then yes an amp that can output 200 W max will do better than an amp that can output 70 W max. If you only need 50 W maximum, then a 70 W rate amp will do just as good.

Amps that can output more voltage/current than needed is good, but if the extra output is not needed, then it will just be there doing nothing, until you need it.

 

[voodooless]

More power to the speakers results in more dynamic peaks and better dynamic range.

But only if you actually turn up the amp.

It does nothing if you listen at low volume and your previous amp already handles all the peak just fine.


There is no correlation between power and sound quality.

 

[Doodski]

But only if you actually turn up the amp.

It does nothing if you listen at low volume and your previous amp already handles all the peak just fine.


There is no correlation between power and sound quality.

Amplifier linearity improvements result in more dynamic peaks and that includes enough power to manage peaks. I've found about a 130 W RMS power amp to be a good number for most speakers and anything beyond that is gravy but I am a firm believer of the more the merrier when it comes to bigger amps but I tend to crank the volume loud.

 

[restorer-john]

People have underestimated how much power they think they need forever.

I would estimate there are perhaps one or two members on ASR who might just have enough power on tap to cover the full audible dynamic range of 16 bit audio in their systems.

 

[Steven Holt]

I would estimate there are perhaps one or two members on ASR who might just have enough power on tap to cover the full audible dynamic range of 16 bit audio in their systems.

So, John, a question : Are you saying that you need to listen at full volume in a concert hall - like setting to get the full audible dynamic range?

 

[voodooless]

I would estimate there are perhaps one or two members on ASR who might just have enough power on tap to cover the full audible dynamic range of 16 bit audio in their systems.

And how many of those two people don’t have hearing damage by now ?

 

[Barrelhouse Solly]

I remember reading a guitar amp site about 20 years ago on the subject of how much amp do you need. One thing I remember is that a 5 watt guitar amp running at max can get as loud as a trumpet at max volume. While I think most people who follow this site regularly know that the relationship between power and perceived volume is not linear I'm thinking that a lot of audio manufacturers would prefer that they didn't.

 

[RayDunzl]

would estimate there are perhaps one or two members on ASR who might just have enough power on tap to cover the full audible dynamic range of 16 bit audio in their systems.

If you mean that you have to hear the quantization noise, or the dither noise, on the CD...

Where would that put the peaks in SPL?

 

[Deleted member 21219]

And if there is enough wattage to cover peaks? Will adding more wattage enhance sound quality?

No. OTOH, as @restorer-john insinuated, "enough wattage" might be more than you suspect.

I'm now wondering if that is true, if sound quality and wattage is related .....

Not in the simplest of terms, no. You need enough wattage (see above again), but high quality sound doesn't come from poor quality amplifiers, regardless of how much wattage they put out. Yes, you need adequate power, but you also need decent quality design.

Jim

 

[radix]

Really, the main thing to look at are the speaker distortion and compression at different SPL. The manufacturer rated "watts" is really pretty meaningless. I don't think they are required to measure THD vs watts, they just pick something. You need to look at the speakers distortion and compression to understand how loud it can go. For your use case of 70 dB SPL (I assume at 1m?) most any decent speaker should be OK. its when you get up to around 85-100 that you start seeing problems or reaonances.

Here's a recent speaker review: https://www.audiosciencereview.com/forum/index.php?threads/jbl-studio-590-speaker-review.47269/

Amir will put in THD graphs, like these:

These are the 86 dB SPL at 1m and 96 dB at 1m. He usually puts a line for acceptable distortion. You can see this JBL is so-so at 86 dB and bad at 96. So that is really the limiting factor for it, not really amplifier power. (this is a powered speaker, not passive, so maybe not the best example here).

Erin's Audio Corner has reviews like this one: https://www.erinsaudiocorner.com/loudspeakers/arendal_1723_thx_monitor/

In addition to the THD @ SPL graphs like Amir does, he includes a compression graph like this. This Arendal is a beautiful speaker it really performs well to at least 102dB SPL @ 1m.

If you look at the Linton (https://www.erinsaudiocorner.com/loudspeakers/wharfedale_linton_85/), it's a mess compared to the Arendal. The 86dB is good, but the 96 starts showing issues and the 102 get bad. This is why in your other thread, I said the Linton's are great if you don't need to go too loud.

 

[restorer-john]

So, John, a question : Are you saying that you need to listen at full volume in a concert hall - like setting to get the full audible dynamic range?

The voltage range between the threshold of audibility in your system (whatever that is) to full level is over 63,000 times for 16 bit audio. Do you have enough power (voltage swing) to cover that?

If just 1uW@8R (0.000001W or 2.83mV. That's less than the output of a MM cartridge!) was the threshold of audibility on your system into speakers in room, you'd need more than 63,000 times that voltage to reproduce the dynamic range of compact disc. Consider that level is roughly the hiss in a typical integrated amplifier if you press your ear to the tweeter. You will not hear that in your listening chair, letalone be able to discern anything intelligible.

Your 'amplifier' would need internal supply rails approaching +/-250V and a power output of 3.9kW per channel. Hence my guesstimate of only a few ASR members having enough power...

But let's go the other way:

Say a Topping LA-90 with so-called "SOTA" test results. I'll be generous and take the 1% (clipping) THD point as 55W RMS@8R (as per Amir's test). That's 21V RMS. 21V divided by 2.83mV (1uW) is 7424 times, or just 77.4dB dynamic range. Not so impressive now is it?

 

[Steven Holt]

Thanks for the reply, appreciate it. While I can't argue with your logic -- seems very good -- I can't help but wonder why Amir includes dynamic range specs in his testing. If you're correct, it has pretty much nothing to do with real world listening. Any thoughts?