When to Add External Amplification to an A/V Receiver

[AcuDefTechGuy]

I could take those Revels off your hands if you need some extra scratch.

I wish there were a crazy audiophile willing to buy all my speakers locally.

Like back then when I was a crazy audiophile buying all the speakers.

 

[JohnnieB]

I demo'd the f208's. What a great speaker. Dealer gave me 1000 off retail. Really wanted them but I had to draw a line somewhere in the budget in order to get everything.

 

[Irvrobinson]

...I had to draw a line somewhere...

What a quaint concept! I wish I would have learned such wisdom. Really.

 

[JohnnieB]

Not sure it was wisdom so much as the reality of it. I felt bad too because the owner was a great guy. We talked for a couple hours about gear and sound. He gave me a great price on a McIntosh triple too. Oh well, maybe someday.

 

[Josuah]

I'm not sure I know how to calculate my score.

Listening: headbanging (105dB peaks at the listening seat to match movies; 115dB peaks for subs at 5Hz)
Room Size: >3000ft^3
Speaker Load: 6 ohms < 90dB efficiency
Bass Management: Crossover with dedicated subs
Score ? Max ?

As far as I can tell that's probably a +6 so I don't know how you can get up to +10?

 

[herbu]

I'm not sure I know how to calculate my score.
As far as I can tell that's probably a +6 so I don't know how you can get up to +10?

In each category you can get: 0 or 1 or 2... not 0 + 1 + 2
The magic number is 5

There is no "+10"

 

[RichB]

In each category you can get: 0 or 1 or 2... not 0 + 1 + 2
The magic number is 5

There is no "+10"

Oh crap, I got an 11

- Rich

 

[gene]

Here is a video Hugo and I shot discussing the heated topic of "Do All Amplifiers Sound the Same?"

 

[alienmuppet]

The effect of psycho-acoustics is amazing. I bought a new expensive cartridge for my turntable recently. I was loving the sound so sat listening to records all evening. Eventually I put a record on I hadn't played before (it was on my house-mate's pile of used records she'd bought but never played). Suddenly I heard a strange thudding sound every second or so. There was a "speed bump" on the record that was causing the needle to pretty much leave the surface of the vinyl and then land again. I was so convinced this had ruined my new cartridge and needle that everything after that sounded thin and not like before. I just couldn't enjoy listening anymore for the rest of the evening, thinking I'd have to replace it.

I eventually compared the sound to some high quality vinyl recordings of the same tracks. They sounded practically identical, no problem at all - certainly nothing lacking at the bottom end like I thought it was. I also posted to a vinyl forum and they said it was extremely unlikely it would have caused any problem. When I calmed down I also could see the "speed-bump" in the record was very small, but I won't be playing it again!

In a past life I used to do live sound engineering. Quiet often I'd get a fairly bogus request from the stage to reduce a certain frequency band. I turned the DFA knob so they could see me doing it until I got an eventual thumbs up. DFA stands for "does f*** all"... The funny thing is I could also confuse myself. Sometimes I would turn the EQ knob on the fully parametric equalizer, changing the frequency range and level, and be convinced it was making a small difference only to discover the EQ bypass for that channel was engaged.

Similarly, I was also into studio recording. Numerous times when tweaking the EQ on cubase I would be convinced it was making a subtle difference, only to again find I had that particular plug-in bypassed, but because I was activity changing a setting that I thought was making a difference, I thought I could hear a difference.

This to me proves that without a blind test, any test is completely invalid. How our minds affect what we are hearing is incredible, but I guess it makes sense since our minds are the squishy organic things that are converting the vibrations to what we perceive as sound.

Also I've stumbled across articles in the past that say a single blind test is often also invalid because of unconscious signals given off by the person doing the testing. They do say that most communication between humans is non-verbal, so I can see how that makes sense.

We also have extremely short "acoustic memory". I'm fairly convinced that unless an A/B test (in double blind conditions) is done so the switching is *immediate*, that you can't possibly be sure of the differences unless they really are obvious (due to faulty equipment or bad tone-matching). So any talk of switching wires or connectors manually rather than via a switch box completely invalidates a test in my eyes at least; it just takes too long - the switch has to be instantaneous and without any "clicking" sound of the switching.

I'm not going to say if I think amps sound different or not as I've never done a double blind test for such a thing. If there is any I suspect the difference is small between well designed amps (when not being over-driven), but that is just pure speculation on my part. If the difference is not small, then how can both amps be well designed since the purpose of an amp is to make the signal coming in bigger than the signal coming out? I suppose the question then would be: which has an output signal closest to the input signal (baring the obvious difference in amplitude) ? If the waveform is faithfully reproduced then it perhaps just comes down to the distortion characteristics as other posts have alluded to.

I'd be interested to see the difference between amps given the same speakers - can't we use a measuring device on the speaker to compare the produced waveforms?

I also found this which I thought was interesting:

Testing audiophile claims and myths

I started investigating this topic (hence I found this thread) when trying to decide in what way to upgrade my A/V receiver. I'm becoming more and more convinced that I just would not notice any meaningful difference between a well priced Yamaha, Denon or Sony, or an outrageously priced Arcam or NAD. I currently have an old NAD 752 that has served me well for 10 years and still sounds good. I'm mainly thinking of upgrading it for functionality reasons rather than sound (i.e. I cannot plug my HDMI cables into the NAD).

 

[JohnnieB]

Oh crap, I got an 11

- Rich

Thanks Rich, LMAO

 

[Goliath]

Gene, I watched your video, but you appear to be misrepresenting the objectivist position. No one claims that all amplifiers sound the same when driven within their linear limits. That is a straw man argument and a false claim.

What evidence shows is that amplifiers working within their linear limits (not clipping), with a low output impedance, level-matched, tend to sound very, very similar to any other non-clipping amplifier with a low output impedance. Just about all solid-state amplifiers cut the mustard. Switch-mode and tube amps? Not so much.

Just to reiterate this important point, all amplifiers would consist of solid-state, switch-mode and tube/valve amplifiers, and again, no one claims all amplifiers sound the same. Just because an amplifier measures differently means they sound differently? Really? So a microscopic change in output impedance is enough to result in an audible change? What about distortion? Is there a such a thing as the known thresholds of hearing?

You also go on to say that no amplifiers have a zero output impedance. There is no evidence that any modern solid-state amplifier can audibly alter the frequency response based on its output impedance, which tends to be very, very low on the average. We don't need perfection in order to attain sonically blameless sound.

How do we know if an amplifier is still within its linear range? By listening to music perhaps? Steadily increasing/decreasing the volume and noticing any changes to the overall character of sound is a common game plan.

The second issue I have with your video is that you seem to think that amplifiers amplifying musical signals and driving real loudspeaker loads are somehow more stressed out than on the test bench.

If your power amplifier was a car, test bench conditions are like driving uphill on a very steep grade for 20 minutes to a half hour at a time while pulling a heavy trailer. Music is like driving across a rolling plain, which is rarely flat, but also never steadily uphill. A resistive load is like a very heavy trailer, while speakers act more like a light load, on the average.

Barring a few poorly designed loads, modern speakers just don't need boatloads of power and if an amplifier can deliver power into a resistive load, driving pure tones, then in reality, driving real audio and drama, with real loudspeaker loads whose impedance varies with the frequency, the task is much, much, much easier in general.

Back to the power amp topic, I could be wrong, but to me, you seem to be of the opinion that power amplifiers are like delicate little flowers that need care and feeding to work well. In fact modern power amplifiers are like turbocharged cars. If you doddle around town and don't press the gas pedal down very far, they are mild-mannered.

If you floorboard them, they have a lot of reserves to pleasure you with. But if you keep an AVR within non-clipping limits, the power delivery would be the same if you had a bigger power amp driving the same load to the same level. Same voltage swings, same current draw - nothing changes, but the available headroom - headroom the speaker can't use, or 'see' or ...

Having a big power amp can be a good thing in some conditions and I won't deny that. All depends how the system is used. Speaking of big power amps, you have some stonking power amps in your own personal system don't you? Do you feel that because your system presumably benefits from this power, that all other systems would benefit by default?

 

[RichB]

If you floorboard them, they have a lot of reserves to pleasure you with. But if you keep an AVR within non-clipping limits, the power delivery would be the same if you had a bigger power amp driving the same load to the same level. Same voltage swings, same current draw - nothing changes, but the available headroom - headroom the speaker can't use, or 'see' or ...

Having a big power amp can be a good thing in some conditions and I won't deny that. All depends how the system is used. Speaking of big power amps, you have some stonking power amps in your own personal system don't you? Do you feel that because your system presumably benefits from this power, that all other systems would benefit by default?

The real trick is figuring out when an AVR would clip.
It is not really that easy to do, thus the guidelines.

- Rich

 

[AcuDefTechGuy]

The real trick is figuring out when an AVR would clip.
It is not really that easy to do, thus the guidelines.

- Rich

Just don't play too loudly and the AVR won't clip. That's the trick.

The best guideline is to buy an AVR with pre-outs for external amp. Chances are people won't need an amp, but if they do need an amp, the option is always there. No need to worry about any scores.

 

[RichB]

Just don't play too loudly and the AVR won't clip. That's the trick.

The best guideline is to buy an AVR with pre-outs for external amp. Chances are people won't need an amp, but if they do need an amp, the option is always there. No need to worry about any scores.

For civilized people:
Amp size = Min(normal Listening Level, Max Speaker Power)

For occasionally uncivilized people:
Amp size = Max(abnormal Listening Level, Max Speaker Power)



- Rich

 

[AcuDefTechGuy]

For civilized people:
Amp size = Min(normal Listening Level, Max Speaker Power)

For occasionally uncivilized people:
Amp size = Max(abnormal Listening Level, Max Speaker Power)



- Rich

For most people:
Amp size = Who cares, just let me watch my movies, TV-series, and music.

Too many good shows and movies to watch, no time to worry about something that will most likely never apply to most people.

Get an AVR with pre-outs. Done. Go watch.

Oh, so you worry about the "too little power will harm your speaker" myth? Don't be. It's nonsense. Your system will either sound good or it will sound bad. Your speakers will be fine either way. If it sounds good, you are done. Don't worry about power amps and scores. Just enjoy your movies, shows, and music.

 

[RichB]

For most people:
Amp size = Who cares, just let me watch my movies, TV-series, and music.

Too many good shows and movies to watch, no time to worry about something that will most likely never apply to most people.

Get an AVR with pre-outs. Done. Go watch.

Oh, so you worry about the "too little power will harm your speaker" myth? Don't be. It's nonsense. Your system will either sound good or it will sound bad. Your speakers will be fine either way.

No, I am not worried. You could connect a 50 watt receiver play it into you Salon2's full range for 30 minutes at reference volume. Are you willing to do that?

I am pretty sure I could use an AVR for movies provided they had sufficient power to drive the Salons full range.
We rarely watch a movie at higher than -20. Last night, we watched THOR and the A51 driving all speakers at full range was only warm to the touch.

Since Revels can handle the power, why use an under-powered amp?

- Rich

 

[AcuDefTechGuy]

No, I am not worried. You could connect a 50 watt receiver play it into you Salon2's full range for 30 minutes at reference volume. Are you willing to do that?

I am pretty sure I could use an AVR for movies provided they had sufficient power to drive the Salons full range.
We rarely watch a movie at higher than -20. Last night, we watched THOR and the A51 driving all speakers at full range was only warm to the touch.

Since Revels can handle the power, why use an under-powered amp?

- Rich

Did I recommend using a 50WPC amp for Salon2?

I always recommend using a 120W-300W amp for more dynamically capable speakers and 60W-120WPC amps for less dynamically capable speakers. It depends on the amps too. ATI amps are known to be stable down to 1 ohms. So I would feel a lot better with a 60W ATI than a 100W AVR.

I sure would not recommend a 300W amp for any speaker (Revel or not) that has a max power rating of 200W because of the risk of mechanical and thermal damage.

But if the question is, if I had only 2 choices for my Salon2 and the 2 choices are a 50W amp or a 2,000W amp, I would pick the 50W amp because I know that too little power will not damage my speakers, but too much power could damage my speakers if accidents and malfunction occur.

 

[RichB]

Did I recommend using a 50WPC amp for Salon2?

I always recommend using a 120W-300W amp for more dynamically capable speakers and 60W-120WPC amps for less dynamically capable speakers. It depends on the amps too. ATI amps are known to be stable down to 1 ohms. So I would feel a lot better with a 60W ATI than a 100W AVR.

I sure would not recommend a 300W amp for any speaker (Revel or not) that has a max power rating of 200W because of the risk of mechanical and thermal damage.

For me that depends.
My brother-in-law is using an A21 with his F206's (max recommended at 200) and he plays music loud.
Revel like ATI builds a robust product, so I am not worried.

But if the question is, if I had only 2 choices for my Salon2 and the 2 choices are a 50W amp or a 2,000W amp, I would pick the 50W amp because I know that too little power will not damage my speakers, but too much power could damage my speakers if accidents and malfunction occur.

There are measurements showing compression with moderate clipping, which contributes to the thermal load.
So I would pick the 2000W amp and configure the Preamp/AVR to a volume limit of reference or -10.
There is no published maximum recommended power for Salons(2)'s, so they must be able to handle 2kw.

Anyway, I do not see evidence of rampant speaker destruction.
Perhaps, the types of folks you find here are a bit more careful then the average user and may also buy more robust speakers.

- Rich

 

[Irvrobinson]

What evidence shows is that amplifiers working within their linear limits (not clipping), with a low output impedance, level-matched, tend to sound very, very similar to any other non-clipping amplifier with a low output impedance. Just about all solid-state amplifiers cut the mustard. Switch-mode and tube amps? Not so much.

I agree, mostly, and in my listening tests that includes tube amps with push-pull output sections.

You also go on to say that no amplifiers have a zero output impedance. There is no evidence that any modern solid-state amplifier can audibly alter the frequency response based on its output impedance, which tends to be very, very low on the average. We don't need perfection in order to attain sonically blameless sound.

John Atkinson of Stereophile has been measuring frequency response anomalies of amplifiers into a simulated speaker load for years, and he has revealed some interesting differences, mostly because output impedance varies by frequency. Whether or not the differences are audible is subject to debate, and is of course speaker-dependent. It is common these days for some speakers to have impedance measurements in the 2 ohm range in the bass, and some amps have rising output impedance below 100Hz, so one could conceive of audible bass response differences, especially considering that deep bass is as much feel as hearing sensitive, and our sense of feel isn't logarithmic like hearing is. So I suppose differences in perception due to output impedance are possible.

The second issue I have with your video is that you seem to think that amplifiers amplifying musical signals and driving real loudspeaker loads are somehow more stressed out than on the test bench.

If your power amplifier was a car, test bench conditions are like driving uphill on a very steep grade for 20 minutes to a half hour at a time while pulling a heavy trailer. Music is like driving across a rolling plain, which is rarely flat, but also never steadily uphill. A resistive load is like a very heavy trailer, while speakers act more like a light load, on the average.

Barring a few poorly designed loads, modern speakers just don't need boatloads of power and if an amplifier can deliver power into a resistive load, driving pure tones, then in reality, driving real audio and drama, with real loudspeaker loads whose impedance varies with the frequency, the task is much, much, much easier in general.

Now I think you're on technically shaky ground. While what you're saying is true for thermal stress, you are incorrect when it comes to signal complexity. Music consists of many frequencies being reproduced simultaneously, and loudspeakers present different electrical characteristics to amplifiers based on frequency, so a music load is electrically far more complex as seen by an amplifier driving a real-world speaker (especially a complex multi-driver speaker with a passive crossover) than just driving a frequency sweep into a test resistor. I believe this is Gene's point, and I think it is valid, and I think that Gene's FFT measurements occasionally show some interesting broad-spectrum effects.

Analogies between electrical circuit behavior and mechanical systems tend to be valid only on the most simplistic level. Water pressure and voltage comparisons are useful, but water under pressure doesn't have impedance and the resulting phase angle effects that are interesting.

Back to the power amp topic, I could be wrong, but to me, you seem to be of the opinion that power amplifiers are like delicate little flowers that need care and feeding to work well. In fact modern power amplifiers are like turbocharged cars. If you doddle around town and don't press the gas pedal down very far, they are mild-mannered.

If you floorboard them, they have a lot of reserves to pleasure you with. But if you keep an AVR within non-clipping limits, the power delivery would be the same if you had a bigger power amp driving the same load to the same level. Same voltage swings, same current draw - nothing changes, but the available headroom - headroom the speaker can't use, or 'see' or ...

I think you've misinterpreted what Gene is saying, and I think an analogy to turbocharged cars is simply incorrect. Nonetheless, I think you are correct, as are many others here, that for many systems with many average usage models AVR amps will work just fine, and that the measured differences are not discernible by most listeners. The issue is that for some systems in some rooms with some listeners some of us, and I'm in this camp, think there are differences in amplifiers that affect our ultimate satisfaction on a system level. I think Gene has the right attitude in looking for reasons why that may be true.

 

[gene]

Gene, I watched your video, but you appear to be misrepresenting the objectivist position. No one claims that all amplifiers sound the same when driven within their linear limits. That is a straw man argument and a false claim.

What evidence shows is that amplifiers working within their linear limits (not clipping), with a low output impedance, level-matched, tend to sound very, very similar to any other non-clipping amplifier with a low output impedance. Just about all solid-state amplifiers cut the mustard. Switch-mode and tube amps? Not so much.

Just to reiterate this important point, all amplifiers would consist of solid-state, switch-mode and tube/valve amplifiers, and again, no one claims all amplifiers sound the same. Just because an amplifier measures differently means they sound differently? Really? So a microscopic change in output impedance is enough to result in an audible change? What about distortion? Is there a such a thing as the known thresholds of hearing?

You also go on to say that no amplifiers have a zero output impedance. There is no evidence that any modern solid-state amplifier can audibly alter the frequency response based on its output impedance, which tends to be very, very low on the average. We don't need perfection in order to attain sonically blameless sound.

How do we know if an amplifier is still within its linear range? By listening to music perhaps? Steadily increasing/decreasing the volume and noticing any changes to the overall character of sound is a common game plan.

The second issue I have with your video is that you seem to think that amplifiers amplifying musical signals and driving real loudspeaker loads are somehow more stressed out than on the test bench.

If your power amplifier was a car, test bench conditions are like driving uphill on a very steep grade for 20 minutes to a half hour at a time while pulling a heavy trailer. Music is like driving across a rolling plain, which is rarely flat, but also never steadily uphill. A resistive load is like a very heavy trailer, while speakers act more like a light load, on the average.

Barring a few poorly designed loads, modern speakers just don't need boatloads of power and if an amplifier can deliver power into a resistive load, driving pure tones, then in reality, driving real audio and drama, with real loudspeaker loads whose impedance varies with the frequency, the task is much, much, much easier in general.

Back to the power amp topic, I could be wrong, but to me, you seem to be of the opinion that power amplifiers are like delicate little flowers that need care and feeding to work well. In fact modern power amplifiers are like turbocharged cars. If you doddle around town and don't press the gas pedal down very far, they are mild-mannered.

If you floorboard them, they have a lot of reserves to pleasure you with. But if you keep an AVR within non-clipping limits, the power delivery would be the same if you had a bigger power amp driving the same load to the same level. Same voltage swings, same current draw - nothing changes, but the available headroom - headroom the speaker can't use, or 'see' or ...

Having a big power amp can be a good thing in some conditions and I won't deny that. All depends how the system is used. Speaking of big power amps, you have some stonking power amps in your own personal system don't you? Do you feel that because your system presumably benefits from this power, that all other systems would benefit by default?

Actually most claims I've seen from people that believe ALL amplifiers sound the same are from those that claim "within linear range". I've never seen anyone qualify that statement based on amp topology. This is in fact a finer point that you are now bringing to the table.

Modern speakers don't need boatloads of power? Really, which speakers? Have you tested very large speakers that have low impedance demands at bass frequencies? What size room would you make this qualification? at what SPL? Again over generalizing....

I never said modern amplifiers are like delicate flowers so in that respect yes you are wrong.

I have BIG power amps in my system b/c my speakers demand them and sound BETTER with them. Not even an $11k Pass Labs amp could properly drive my speakers like the Emotiva Monoblocs especially when listening to Blu-ray audio with no compression. My situation isn't the norm. I am running my speakers full range with ALL LFE routed to them.

I understand your argument and you are welcome to believe what makes you happy. Continue using your receiver amp, I am not asking you to upgrade, nor am I even implying that you should. I have my own beliefs based on: designing amps for a living, testing amps for a living, testing large amounts of speakers and electronics for over a 15 year period and most importantly, doing controlled listening tests to make determinations.