Amps and Recievers- Tonal qualities???

[JAD2]

OK, this one always baffled me as to why its even said.
Amps and recievers sound different!!!!


Now I can understand how a small full range speaker doesnt need much power.
A set of 2 ways would need more.
Based on magnet size, driver size, driver material, number of drivers and so on I can fairly easily understand the power aspect.
So a cheap amp that cant maintain a constant non wavering power and a given volume setting would effect the sound coming out. It seems to me that bass performance and lower midrange is effected first. Those use the larger drivers with heavier magnets etc and if they couldnt run at full power without a dropoff the speakers used would play higher frequencys louder thus creating a bright array.
So based on the speakers sound appearance, size of drivers, number of them would determine how they played according to how the power is applied.

Now there would seem to be a level which this would no longer happen. 50 watts rated as and example used on 2 ways under 6 1/2 inches of woofer size that didnt drop off in power before it clipped should not sound any different between makers. After all the power is being maintained with no dropping off, using the same type and array of internal parts which means everything is equal within reason. WHY?? would anyone say it sounds different?? A reciever/amp should play 20-20,000 and with no dropoff in power levels, no area would be weak creating tonal differences.There not made as crossovers etc, so why!!!


The reason I ask this, is one it really doesnt make much sense.
2 I bought a low to mid entry level receiver and know it. I am thinking of upgrading, but like the tonal qualities of what I have now before it begins to peak. What I mean is I can start out at low volume, sounds OK and raise the level and and sounds the way I like it, but at a point it just seems to go flat, wont go louder in volume and I could stand somewhat more and I know thats a lack of power, its dropping off.
But if I change manufacturers etc, then I could surfice the tonal qualities I have now?? Doesnt make sense, but I'm asking for SOLID reasoning. I can get other brand named receivers for much less than my current make is in a upgrade, that have more power and dont fall off in power according to some ranking testing data thats out. Then theirs others that are much more than I'd like to cap spending on, but also would if a deal can be made, do it!!

 

[tbewick]

Now I can understand how a small full range speaker doesnt need much power.
A set of 2 ways would need more.
Based on magnet size, driver size, driver material, number of drivers and so on I can fairly easily understand the power aspect.

The acoustic power output of a loudspeaker diaphragm is proportional to the size of the diaphragm. A larger diaphragm will radiate more efficiently at lower frequencies. Most domestic speakers are fairly inefficient, and smaller ones probably more so. Using smaller cabinets means that bass output is usually reduced.

The power handling capability of a loudspeaker is a function of the voice coil thermal capacity. You should note that loudspeaker manufacturers often just say a rated power output. The value chosen is purely the decision of the manufacturer. If a power handling figure is given and a standard specified for this measurement, e.g. an EIA standard, then the power handling value can be compared with other similarly specified loudspeakers.

So a cheap amp that cant maintain a constant non wavering power and a given volume setting would effect the sound coming out. It seems to me that bass performance and lower midrange is effected first.

It's difficult to know whether such a reduction in the bass output is a result of a loudspeaker or a power amplifier limitation. If you were to compare the subjective performance of power amplifiers, then it is essential you do so in a properly controlled test.

I've heard that a good rule of thumb is to allow 3 dB of amplifier headroom. This means that you should treat a 100 watt amplifier as a 50 watt one. This helps to compensate for the fact that most speakers don't show an 8 ohm impedance across their entire frequency range. This is especially important with transients that can occur in music and speech, which can require more current than the rated impedance might suggest.

Those use the larger drivers with heavier magnets etc and if they couldnt run at full power without a dropoff the speakers used would play higher frequencys louder thus creating a bright array.
So based on the speakers sound appearance, size of drivers, number of them would determine how they played according to how the power is applied.


Now there would seem to be a level which this would no longer happen. 50 watts rated as and example used on 2 ways under 6 1/2 inches of woofer size that didnt drop off in power before it clipped should not sound any different between makers. After all the power is being maintained with no dropping off, using the same type and array of internal parts which means everything is equal within reason. WHY?? would anyone say it sounds different?? A reciever/amp should play 20-20,000 and with no dropoff in power levels, no area would be weak creating tonal differences.There not made as crossovers etc, so why!!!

The power handling requirements of a typical loudspeaker are very complex, and designing a mathematical model for this behaviour for an individual loudspeaker is difficult. The specifications given for the speaker and amplifier are there to be useful for typical system usage. An amplifier that can maintain a flat frequency response across the full audio spectrum at a high, continuous power output suggests that it is well-designed. The actual measurement does not reflect the real-world requirements called upon the amplifier by the loudspeaker, but serves as a useful, objective comparison between amplifiers.

The reason I ask this, is one it really doesnt make much sense.
2 I bought a low to mid entry level receiver and know it. I am thinking of upgrading, but like the tonal qualities of what I have now before it begins to peak. What I mean is I can start out at low volume, sounds OK and raise the level and and sounds the way I like it, but at a point it just seems to go flat, wont go louder in volume and I could stand somewhat more and I know thats a lack of power, its dropping off.
But if I change manufacturers etc, then I could surfice the tonal qualities I have now?? Doesnt make sense, but I'm asking for SOLID reasoning. I can get other brand named receivers for much less than my current make is in a upgrade, that have more power and dont fall off in power according to some ranking testing data thats out. Then theirs others that are much more than I'd like to cap spending on, but also would if a deal can be made, do it!!

There have been tests done between power amplifiers to find out if they sound different or not. One test by Martin Colloms for Hi-Fi News showed that there were statistically significant differences between units. Another earlier test by Quad showed no differences. Of course, these tests are only useful when the amplifier is not clipping, and at normal listening levels, this should be the case. I would only bother getting a new amplifier if it had a considerably higher power output than your old one - 200 watts instead of 100 watts only gives you 3 dB notches more on your volume control. The continuous power output spec may not relate very well to the real demands placed on the amplifier by the loudspeaker, but it is still a useful objective comparison of amp performance. Peak current capability is meant to be important, but I don't know if this spec has been standardised.

I would say that the reported subjective differences between most modern power amps (not valve ones) are fairly unreliable.

 

[AndrewLyles]

I've heard that a good rule of thumb is to allow 3 dB of amplifier headroom. This means that you should treat a 100 watt amplifier as a 50 watt one.

I would only bother getting a new amplifier if it had a considerably higher power output than your old one - 200 watts instead of 100 watts only gives you 3 dB notches more on your volume control.

Is there some kind of equation/formula that can be used to derive how my db of increase you will get per watt? Or am I over simplifing the matter?

 

[mtrycrafts]

Is there some kind of equation/formula that can be used to derive how my db of increase you will get per watt? Or am I over simplifing the matter?

It is logarithmic. I don't have that formula for you, but with a 100 watt amp, you need 200 watts to increase spl 3 dB. A 1 dB increase would be about 25% over 100 watts. a 2 dB increase would be about 158 watts. So, about a 26% increase for each dB of want.

 

[Buckeyefan 1]

Is there some kind of equation/formula that can be used to derive how my db of increase you will get per watt? Or am I over simplifing the matter?

You are oversimplifying the matter. A 100 watt McIntosh amp is not equivalent to a 100 watt Sony AVR amp. They will sound and perform differently when pushed to their limits. Wattage can react to a speakers impedance like a power band in an internal combustion engine. You'll feel the greatest amount of torque at a certain rpm.

Some highly efficient speakers will reach high dB's quickly, then distort. Other demanding speakers will take every bit of current an amplifier has to sound their best at high output.

To sum it up, the speakers you chose will determine how your amp will perform, not forgetting the size of the listening room as well as the reflectivity/absorption properties of your room.

 

[tbewick]

You are oversimplifying the matter. A 100 watt McIntosh amp is not equivalent to a 100 watt Sony AVR amp. They will sound and perform differently when pushed to their limits.

This is only speculation and is not based on any reliable subjective or objective measurement. Just because it says Quad or Naim or McIntosh on the amplifier's box does not make something a good product. In regard to sound quality, I don't know how much the tonal qualities will differ between amplifiers. Earlier I referred to the Martin Colloms' test in Hi-Fi News, but I haven't actually read this.

If you want another specification for examining the ability of the amplifier under low impedance conditions, look for the continuous power output into 4 ohms. It should be double the value of the power output into 8 ohms. The only amps I've seen that can manage this are usually 200 watts (or more) into 8 ohms.

In most cases I think that the idea of leaving amplifier headroom is sufficient to allow for high peak current demands from the loudspeaker.

Wattage can react to a speakers impedance like a power band in an internal combustion engine. You'll feel the greatest amount of torque at a certain rpm.

Sorry Buckeyefan1, could you explain this analogy further? I remember someone once trying to explain torque to me and I got confused.

Is there some kind of equation/formula that can be used to derive how my db of increase you will get per watt? Or am I over simplifing the matter?

There probably is, but I like to use the dBW method. Start off with your speaker sensitivity, e.g. 89 dB. This is the sound power output produced by the speaker at 1 metre with 1 watt input. For each doubling of watts, you get 3 dB more speaker volume. This will depend on whether the speaker output is linear with regard to input voltage, but it usually is. Therefore-

at 1 metre:

1 watt = 89 dB SPL
2 watts = 92 dB SPL
4 watts = 95 dB SPL
8 watts = 98 dB SPL
16 watts = 101 dB SPL
32 watts = 104 dB SPL
64 watts = 107 dB SPL etc..

The inverse square law tells you the direct sound pressure level fall-off with distance. This of course ignores acoustical effects. I don't know the formula but at 2 metres the sound level is around 6 dB below the level at 1 m, and at 3 metres it's around 10 dB less.

With all this, you can get a rough, conservative estimate as to the maximum sound output from your system, e.g. 100 watt amp, 89 dB sensitivity speakers, 3 metres sitting distance = max. SPL is around 94-97 dB. This is treating the 100 watt amp as a 34 watt/64 watt one to allow for amplifier headroom.

The speaker sensitivity is usually found using pink noise and sound output will varying according to frequency at higher volumes. In other words, the maximum bass output of the loudspeaker will usually hit a maximum before the mid-range and higher frequencies. One other thing worth knowing is that the tweeter power handling capacity is usually much less than that of the woofer, perhaps only 20 watts or so. Modern pop music recordings tend to contain more high frequency energy than old recordings, so it good to keep the volume at a sensible level to protect the speaker's tweeters.

 

[JAD2]

I know its very complex and I tried to simplify the question as much as I could for a generalized answer that would shed some in-site on what we read in posts.
I've seen the charts to DB versus wattage.
I've read where one amp has totally different tonal qualities than others and this doesnt make a whole lot of sense if the playing field was semi level.
What I mean is you have 2 amps, 3, whatever and each doesnt drop off, go into clipping etc until 80% of its rating is used up, so if they were 100 watt rated each would hit 80 watts equally before clipping etc, there is no reason it should sound tonally different using the same speakers. Whats there that would change tonality??
Now like Buckeye had mentioned between a Sony and good name I have seen some specs that offer why, least to me!
I've been poking around looking at specs. No where is there a standard in specs and NO ONE has straight answers to anything on these. All I see is ,dont ever go by specs and if you ask something along whats best for my setup you get a million and one answers, all opinion.

Looking at the likes of Sony, Yamaha, Pioneer and some more NAMES, from whats considered by them there entry to high level stuff I find funny specs.
You see @1hz- that just says stay away from any wattage rating they call out.
I look at wattage useage, total amps used is rare, but 130 watts a channel and it uses 280. I know the receiver itself is going to use at least 40 watts of power just to run and depending on how strong its upconverting, signal processing etc it could run up to 90 watts. Your 130 is right out the window in 2 channels, cause after the initial power useage of the receiver, there isnt enough left at 2 channels to hit 130, and 5 channels, 6, 7 forget it. Thats when you would see 20-20,000 go to @ 1 hz ratings on multi channels. You cant put out more than you take in.
Some might have 600 continuous rated, with 1100 max, but at a much higher THD rating. This tells ME, at lest it seems sensible, that up to 600 it should do good. Take out, since this unit has all kinds of processing, around 80+ watts for the receiver itself, that leaves 74 watts a channel at 7 channels since its a 7.1 system and anything over that, it will begin to distort sounds. 74 wouldnt be double what I have now, but thats what I'll get into in a bit.

Now like Denon, Onkyo, Harmon Kardon, Marantz and others the ratings game plays differently.
20-2000 rated on all channels, some with 10 watts or so more on 2 channel then multi.
X wattage just being on, or doesnt say to max wattage or amps used max, with .0X or so THD. This tells me at the same 1100 watts as above on 7 channels. I got around 145 watts per channel and THD, distortion, noise whatever wont rise and I'll have somewhere near 145 watts of pure sound.

Yes the ratings are confusing, but looking at what I see, some seem to show direction of what you actually could see.

I have a 65 watt per channel setup, it uses 4.2 amps max so I trust I'm getting more power than something that also says 65 watts per channel that only uses 320 watts max. Just before what I would like my ears to take max, mine shows signs of dropping out, I'd like to maximize it.
My example above with 1100 watts max was a Yamaha, $1200 and it seems at 74 watts a channel, not double the current setup, its gonna lack. That just seems steep when a $699 Harmon Kardon, $800 Denon and so on can hit 100 watts + dont have funny call out ratings and appear to be able to hold that power which I think will be double where mine falls out.

Thats where tonal qualities, which was the original question comes in. These seem to hold their power. I'm not a NAME person and I like the sound I have now, but want some more volume to it for those days the kids and wife arent home so I can go deaf!!! If I go from one brand to another, is it really that much different??
Fancy goo gadgets/features like HDMI switching, upconversion for video dont mean anything to me and wont be used all though those features change from one maker to the other. I got RG11 cable to mid point of the house and quad shielded RG6 to 4 TV's from that point. The main TV which the system goes on has DVI, DVI runs from my Oppo thats coming, Samsung for now to the TV and component which looks better for cable than DVI. Optical is used for DVD and digital for cable. I dont need fancy switching and digital connections for audio are just fine for me and dont plan on going to HDMU at all for at least til the TV says goodbye!!! Hopefully thats years dont the road, 10-15 to be exact!!

Sorry for the book, but I think I needed to get it all layed out to get the answer I seek and others might be interested in knowing the scope of it!

Any of this make sense??? Is my thinking alone the right line!! Speakers are new and will be staying also for this time period.

 

[JAD2]

Modern pop music recordings tend to contain more high frequency energy than old recordings, so it good to keep the volume at a sensible level to protect the speaker's tweeters.

One, I dont listen to anything new, its Jazzy related for the most part unless I get into a Pink Floyd moment.
Second the tweeters I upgraded to because I didnt like the originals are rated the same as the main drivers. According to Polk, because I did call on this when I made the upgrade for crossover changes and added a 5 1/4 midrange to my mains that they can handle 60 watts + or minus per driver.

If this makes any difference!! In my case!!

 

[PENG]

If you want another specification for examining the ability of the amplifier under low impedance conditions, look for the continuous power output into 4 ohms. It should be double the value of the power output into 8 ohms. The only amps I've seen that can manage this are usually 200 watts (or more) into 8 ohms.

Since losses increase with current, e.g. voltage drop, I would think that it is easier for a manufacturer to simply under rate their 8 ohm power output in order to show "doubling down" to 4 ohms. Most near high end manufacturers won't bother to play such games, hence very few will reflect the double down numbers in their specifications.


There probably is, but I like to use the dBW method. Start off with your speaker sensitivity, e.g. 89 dB. This is the sound power output produced by the speaker at 1 metre with 1 watt input. For each doubling of watts, you get 3 dB more speaker volume. This will depend on whether the speaker output is linear with regard to input voltage, but it usually is. Therefore-

at 1 metre:

1 watt = 89 dB SPL
2 watts = 92 dB SPL
4 watts = 95 dB SPL
8 watts = 98 dB SPL
16 watts = 101 dB SPL
32 watts = 104 dB SPL
64 watts = 107 dB SPL etc..

The inverse square law tells you the direct sound pressure level fall-off with distance. This of course ignores acoustical effects. (An important point, this law applies to "open field", in a room the SPL typically does not fall off as much with distance). I don't know the formula but at 2 metres the sound level is around 6 dB below the level at 1 m, and at 3 metres it's around 10 dB less.

Sorry, I added my comments in bold italic.

 

[tbewick]

I've seen the charts to DB versus wattage.
I've read where one amp has totally different tonal qualities than others and this doesnt make a whole lot of sense if the playing field was semi level.
What I mean is you have 2 amps, 3, whatever and each doesnt drop off, go into clipping etc until 80% of its rating is used up, so if they were 100 watt rated each would hit 80 watts equally before clipping etc, there is no reason it should sound tonally different using the same speakers. Whats there that would change tonality??

I think that the argument for differences in tonal quality is that the continuous power output measurement does not reflect real-world demands made upon the amplifier by the loudspeaker. As I said, Martin Colloms for Hi-Fi News did find statistically significant subjective audible differences between power amplifiers. Quad did not, neither did a test done in Stereo Review (this article is available through moderator Rip Van Woofer's signature link). The loudspeaker does not behave like an 8 ohm resistor, and a typical musical signal is not at all like a sine wave. It is however still a useful measurement because it allows you to objectively compare the performance of power amplifiers. I still think that the reported subjective differences between amplifiers tend to be exaggerated.

I've been poking around looking at specs. No where is there a standard in specs and NO ONE has straight answers to anything on these. All I see is ,dont ever go by specs and if you ask something along whats best for my setup you get a million and one answers, all opinion.

My impression is that the marketing department will review the specifications of a product and decide which ones look good. Normally the reported continuous power output into 8 ohms is a reliable figure. It should have a THD figure and be across the entire audible bandwidth. www.homecinemachoice.com and other hi-fi review magazines do their own lab checks on power amplifier performance.

Looking at the likes of Sony, Yamaha, Pioneer and some more NAMES, from whats considered by them there entry to high level stuff I find funny specs.
You see @1hz- that just says stay away from any wattage rating they call out.

Performance into 1 kHz is probably less demanding on the amplifier than across the whole audible bandwidth. In some ways, the 20 Hz - 20 kHz test is less realistic, in that distortions in the high and low parts of the spectrum are less audible than at 1 kHz.

I look at wattage useage, total amps used is rare, but 130 watts a channel and it uses 280. I know the receiver itself is going to use at least 40 watts of power just to run and depending on how strong its upconverting, signal processing etc it could run up to 90 watts. Your 130 is right out the window in 2 channels, cause after the initial power useage of the receiver, there isnt enough left at 2 channels to hit 130, and 5 channels, 6, 7 forget it. Thats when you would see 20-20,000 go to @ 1 hz ratings on multi channels. You cant put out more than you take in.

I would ignore the watts figure on the back of the amplifier. Just go on the specifications, as these directly relate to the pre/power amplifier components. Assuming the integrated amplifier is well-designed, then the unit should be able perform sufficiently well in both the pre- and power amp sections.

Some might have 600 continuous rated, with 1100 max, but at a much higher THD rating. This tells ME, at lest it seems sensible, that up to 600 it should do good.

I would only recommend looking at the continuous power output at low THD's. The usefulness of this measurement is in comparing equipment. A mid-range A/V receiver costing £600 might be 100 watts, one costing £2000 might be 160 watts. Usually weight is a good indication of the capability of the power supply.

Now like Denon, Onkyo, Harmon Kardon, Marantz and others the ratings game plays differently.
20-2000 rated on all channels, some with 10 watts or so more on 2 channel then multi.
X wattage just being on, or doesnt say to max wattage or amps used max, with .0X or so THD. This tells me at the same 1100 watts as above on 7 channels. I got around 145 watts per channel and THD, distortion, noise whatever wont rise and I'll have somewhere near 145 watts of pure sound.

The 1100 watts specs quoted by some mid-range A/V receivers are nonsense. Go on the continuous power output into two channels. If you truly want 1000 watts + per channel, then you'll need to buy expensive and heavy monoblock power amps. You really shouldn't need that much power output in a typical home.

I have a 65 watt per channel setup, it uses 4.2 amps max so I trust I'm getting more power than something that also says 65 watts per channel that only uses 320 watts max. Just before what I would like my ears to take max, mine shows signs of dropping out, I'd like to maximize it.
My example above with 1100 watts max was a Yamaha, $1200 and it seems at 74 watts a channel, not double the current setup, its gonna lack. That just seems steep when a $699 Harmon Kardon, $800 Denon and so on can hit 100 watts + dont have funny call out ratings and appear to be able to hold that power which I think will be double where mine falls out.

Manufacturers don't use leave a consistent amount of headroom in their power output specifications. This is why it's worth looking at independent reviews of power amplifiers. The website link I gave earlier states the tested power output at a 'fidelity firewall' with a very low THD into 8 ohms, and the power output at the onset of clipping, ~1 % THD.

Thats where tonal qualities, which was the original question comes in. These seem to hold their power. I'm not a NAME person and I like the sound I have now, but want some more volume to it for those days the kids and wife arent home so I can go deaf!!! If I go from one brand to another, is it really that much different??

I think you'll get more noticeable improvement concentrating on room acoustics than on swapping amplifiers around. That's not to say the amplifier isn't important, but I think that the amplifier should be transparent unless you have the volume too high.

 

[Nick250]

Great thread. Couple of things I think about.

Might not the company that makes amps/receivers/prepro build in a sonic signature to distinguish themselces them from their competitors? And I certainly have the urge to get an exteranl amp to augment my 3806 even though logically, with the data I am aware of, it makes no sense to do so and that my system sounds darned good already. The "what if" syndrome it you will.

Torque is the absolute twisting force usually measured in "foot pounds" for car engines. It varies with the RPMs. For example an engine might have 50 foot pounds of torque at 1000 RPMs, 150 foot pounds of torque at 3000 RPMs, 200 foot pounds of torque at 2500 and 175 at 4000 RPMs.

Nick

 

[enigmasse]

The speakers I have as my mains handle 200w continuous. I am in the market searching for a clean 200w/ch amp. I have heard a doubling rule: Having an amp that can handle twice the power than the speakers will sound best. There is no way I can get these above 30 watts without being abnoxiously loud. Am I safe with a 200w amp? I am sure I am fine though I do not understand this rule.

Also, based on 104 dB sensitivity, 121 dB maximum SPL and 200w continuous:
1 watt = 104 dB SPL
2 watts = 107 dB SPL
4 watts = 110 dB SPL
8 watts = 113 dB SPL
16 watts = 116 dB SPL
32 watts = 119 dB SPL
64 watts = 122 dB SPL
How can these speakers possibly handle 200w? Is the impedance really playing that much of a role?

 

[JAD2]

Great thread. Couple of things I think about.

Might not the company that makes amps/receivers/prepro build in a sonic signature to distinguish themselces them from their competitors? And I certainly have the urge to get an exteranl amp to augment my 3806 even though logically, with the data I am aware of, it makes no sense to do so and that my system sounds darned good already. The "what if" syndrome it you will.

Torque is the absolute twisting force usually measured in "foot pounds" for car engines. It varies with the RPMs. For example an engine might have 50 foot pounds of torque at 1000 RPMs, 150 foot pounds of torque at 3000 RPMs, 200 foot pounds of torque at 2500 and 175 at 4000 RPMs.

Nick

Sonic signature!!!!!!!!! OK, sounds like and answer and a good solid one at that, but how????

And torque!!! Ah now were into something I do understand.

But how would it apply to receivers??

Lets see for simplicity, torque gets the weight to move at X speed, then horsepower comes in to sub stain it. Alot of horsepower with low torque numbers would take longer to get to X speed than a high torque lower horsepower application, but then may have trouble sub-staining it at speed because of the lower horsepower.

OK, I think where at the efficiency of the amp now and where my question comes in. My amp has what it needs to get it up to speed, then dies out before it can be sub-stained where I'd like it to be!!

 

[PENG]

Mechanical Power Forumla:

Power=2πNT, where N is the angular velocity and T is the Torque.

Compare to the Electrical Power Formula:

Power=V*I*cosØ or I square*R, or V square÷R

There is some analogy in that, T is Angular velocity (RPM, or frequency) dependent, whereas I is impedance, hence frequency dependent.

You can have two engines both rated 100 h.p. but one may have a peaky curve, i.e. you get 100 h.p. in a narrow RPM band, while the other one could have a much flatter curve, so you would get that 100 h.p. for a much wider RPM band.

 

[JAD2]

Mechanical Power Forumla:

Power=2πNT, where N is the angular velocity and T is the Torque.

Compare to the Electrical Power Formula:

Power=V*I*cosØ or I square*R, or V square÷R

There is some analogy in that, T is Angular velocity (RPM, or frequency) dependent, whereas I is impedance, hence frequency dependent.

You can have two engines both rated 100 h.p. but one may have a peaky curve, i.e. you get 100 h.p. in a narrow RPM band, while the other one could have a much flatter curve, so you would get that 100 h.p. for a much wider RPM band.

English Please!!
I understand the RPM thing where it applies, but mixed in with audio and my original question, you LOST me!!!
Not completely, but I cant move it over to answer my question!!

 

[tbewick]

The speakers I have as my mains handle 200w continuous. I am in the market searching for a clean 200w/ch amp. I have heard a doubling rule: Having an amp that can handle twice the power than the speakers will sound best. There is no way I can get these above 30 watts without being abnoxiously loud. Am I safe with a 200w amp? I am sure I am fine though I do not understand this rule.

Also, based on 104 dB sensitivity, 121 dB maximum SPL and 200w continuous:
1 watt = 104 dB SPL
2 watts = 107 dB SPL
4 watts = 110 dB SPL
8 watts = 113 dB SPL
16 watts = 116 dB SPL
32 watts = 119 dB SPL
64 watts = 122 dB SPL
How can these speakers possibly handle 200w? Is the impedance really playing that much of a role?

Those must be horn-loaded speakers. Horns can play so loud because they are more efficient than conventional domestic designs. You can find out more about speaker impedance here -

http://www.epanorama.net/documents/audio/speaker_impedance.html

with a quote from the above link -

"...The point being is that a statement like "The higher the impedance, the lower then efficiency," as a generalization has NO basis in physical fact"

I found this link on the Rane Audio website, under 'Amplifier dummy load' -

http://www.rane.com/par-a.html

The sensitivity measurement is usually made using pink noise. This means that at 122 dB SPL the amplitude response versus frequency will probably differ to the response at a lower volume. It will probably be less flat.

I got this link a while back from mtrycrafts and it is also linked to from the Rane web site:

http://www.dself.dsl.pipex.com/ampins/pseudo/subjectv.htm

It's written by an engineer called Doug Self. It's a bit of a rant but it's probably worth looking at. The site has lots of other stuff about power amplifiers.

Might not the company that makes amps/receivers/prepro build in a sonic signature to distinguish themselces them from their competitors? And I certainly have the urge to get an exteranl amp to augment my 3806 even though logically, with the data I am aware of, it makes no sense to do so and that my system sounds darned good already. The "what if" syndrome it you will.

If they do, then I think it bad design, seeing as most people want their power amplifier to amplify the original signal faithfully and do nothing else. Valve amplifiers are meant to have some effect on sound quality, which is something to do with them adding harmonic distortion. The Doug Self website has more about this. If the pre-amplifier is doing anything to the original signal, then it should tell you. The fact that specifications for good pre- and power amplifiers show flat frequency response, low harmonic distortion, etc. would suggest that transparency is the design goal.

 

[mtrycrafts]

The fact that specifications for good pre- and power amplifiers show flat frequency response, low harmonic distortion, etc. would suggest that transparency is the design goal.

Yep. And when transparency is not the goal, it will show up on a test bench.

 

[mtrycrafts]

I've read where one amp has totally different tonal qualities than others and this doesnt make a whole lot of sense if the playing field was semi level.
.

The playing field is rarely level
One has to be skeptical of such stories of unknown quality and questionable reliability

But then, if the playing field was level, there would not be so many still in business as they would not be selling for such high prices as many sell at.

 

[mtrycrafts]

As I said, Martin Colloms for Hi-Fi News did find statistically significant subjective audible differences between power amplifiers..

Which one is this?
In one of his tests 1986, he ignored 25% of the trials. That would certainly alter the results.

I think you will also like this reading:

http://home.att.net/~Wirebnder/articles/article_14.htm

A bit long but most interesting history of the early days, yet, not much has changed

 

[PENG]

English Please!!
I understand the RPM thing where it applies, but mixed in with audio and my original question, you LOST me!!!
Not completely, but I cant move it over to answer my question!!

Let me try again. Combustion produces pressure acting on the piston of the cylinders of an I.C. engine, resulting in force. That force acts on the crank shafts etc., resulting in torque. This torque, if high enough, will overcome the mechanical/air resistance/friction and the inertia of the mass, causing the engine's output shaft to turn at the desired RPM. The higher the torque, the quicker it will accelerate. At a given torque, the lower the mechanical/air resistance/friction and the inertia of the mass (in physics term, moment of inertia), the higher the RPM.

Back to audio amplifiers, it is voltage that causes current to flow into an impedance. So I would say if one wants to compare the two, voltage would be like torque, current would be like speed and impedance would be like the mechanical/air friction and resistance that torque must overcome.

Think of it this way, at a given voltage, lower impedance results in higher current as long as the power suppy/amplifier can handle the current. Likewise, at a given torque, lower mechanical/aero resistance results in higher speed (RPM for angular motion), as long as the fuel supply/internal combustion and the associated mechanical system can handle the RPM (speed).