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post #451 of 637 Old 02-18-2014, 11:21 AM
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I just want to thank you for this thread cause I've read through some of your posts and it certainly solves some of my past and present problems!
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post #452 of 637 Old 02-18-2014, 11:40 AM
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Originally Posted by spkr View Post

When I worked as a salesman, my duty was to make the consumers spend as much as possible and I had to say anything to make them feel that they need to. By "anything", it includes lies. Not long after, my humanity got the better of me and I decided to get out of that line of work.

Keep my explanation of "anything" in mind whenever you listen to or read what salesman says.

Very unusual. You apparently worked for a two bit outfit. During my life I've been a salesman, sales trainer, sales manager, national sales manager, regional sales manager, vice president of sales, president of a sales company and a few other sales related positions. I've never lied to a customer or taught someone to lie to customers or even heard of successful sales people lying to customers. It is not a way to run a business. If I were asked to lie to customers I would do what you did.
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post #453 of 637 Old 02-18-2014, 11:51 AM
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Originally Posted by UndersAVS View Post

Your advice sounds like sales advice, not an exact model. You suggested that he "buy as much power" as he can afford.

I think some of the power levels in consumer gear these days is ridiculous. It's done because we can. In the 1970s it was quite an accomplishment to build a 200wpc amp. Remember the Dynaco 400, the Marantz 250, the Phase Linears, Ampzilla. These products were on the cutting edge power semiconductor wise and literally on the edge of instant failure - as many did taking speakers along on the ride to hell.

Today reliable power semiconductors are common place and cheap. Designs are optimized by computer at a very low cost. The only expensive component really left is the power transformer. And by using a switch mode power supply we can fix that expense too. Above all high power sells. Never mind the realistic requirements. So we have AVR that tout 200wpc x 5 or 7 channels.

I am currently building some pure class A amps for my LCR tweeters. I was auditioning them this past weekend driving my Boston full range music speakers. I gotta tell you, 20 watts was more than enough. There was no clipping, I was watching a scope across the output. I see no reason these could not be used as a full range amplifier.

Bottom line is clean mid to low power is a much better choice for sonic clarity than brute force. I do acknowledge that some speakers need high power but aren't they more or less obsolete designs from the 70s? Modern computer aided speaker designs seem to be much more efficient.

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post #454 of 637 Old 02-18-2014, 11:56 AM
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Originally Posted by FMW View Post

Very unusual. You apparently worked for a two bit outfit. During my life I've been a salesman, sales trainer, sales manager, national sales manager, regional sales manager, vice president of sales, president of a sales company and a few other sales related positions. I've never lied to a customer or taught someone to lie to customers or even heard of successful sales people lying to customers. It is not a way to run a business. If I were asked to lie to customers I would do what you did.
It depends on which industry you are in. Plus, there's a difference between sales rep, floor salesman, door to door salesman ...etc. Also, there are different severity of lies and deception is one form of lie. Not unusual at all.
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post #455 of 637 Old 02-18-2014, 12:19 PM
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Originally Posted by kgallerie View Post

So what you're saying is that its ok to use the SPL calculator as a data point, but make sure you understand the limitations when determining what amp to buy.
No. There are things one has to understand not only with the calculator but the numbers you plug into it. Please read my original post a page or so back.
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But to go along with that, we have several people here all saying that they found the calculators to be quite conservative. That is also information that can be taken into account.
First let set aside any claims where data is not provided. Folks are just selling an opinion however way they can. Recall my first question of how one knows that almost all people have enough amplification. I asked for details on that and there is sound of crickets smile.gif. For the ones that have data like Arny, I explained how it is important to test at multiple frequencies and angles. I have not seen any data related to that. Think of measuring at 50 Hz for example. What if there is a resonance at that point in your room? That could be as high as 10 to 20 db. The calculator did not take that into account. So if it happens that the the data agrees with the calculator, then it is actually the wrong results by 10 db!

Here is a set of measurements for another purpose but does help in this area:

i-H8n7Nfp-L.png

The measurements are the critical distance or the point at which the direct sound = reflected sounds. Notice how it is highly frequency specific. Another way to read this is that as you move back from the speaker the amount that the level drops is frequency specific.

I did see Wayne express his experience for the equipment he has tested and I accept that as data point. As I said you can build up experience with one set of speakers and amps and develop a feel for what they do in real rooms.
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Have you ever heard of someone who used an SPL calculator, bought an amp based on the result, and found the amp not to be adequate? I haven't.
No, but then again I have not seen anyone buy elephants either. biggrin.gif I don't keep track of who is buying an amp using what. As I explained above, the measurement of SPL relative to the calculator is very complex and subject to many parameters. Your speaker manufacturer may have been honest salesman and given you the right number. Or he could have been like member spkr and lied to you by gaming the sensitivity value to get numbers that throw off your power computations by a factor of 2 or more. Such cheating is common. So if folks are seeing agreement across the board, or more conservative value, then they are measuring things wrong.
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So basically, as a professional you are using an empirical design, then if it doesn't work trial and error? Most consumers don't have those options. But on top of that, the size and orientation of the room plays so much into the required power, if you're using similar systems in most of your applications, I would be willing to bet a lot of people are spending a lot more than they need to.
No, that is not what I said. I said that professionals build up experience and use that rather than some calculator online with numbers plugged into it that are meaningless often. My builder for example built me a shed. He did not need you to tell him what to use for the walls. From experience he knows the framing he needs for that kind of structure. The Pros can use sophisticated methods like I mentioned (e.g. clip detection) but just like my builder, they have sufficient experience to get the answer much more conveniently.

As to what consumers need to do, first of all they could get equipment returned. Any retailer here will accept returns. Even Amazon does, sans shipping. So that is not the problem. The problem seems to me that the fact that I point out problems in the methodology, it is my responsibility now to solve the user problem. It is not smile.gif. As I said, the science doesn't owe us simple answers. The only correct answer is to instrument the amplifier to see if it is clipping. That is the right answer and it requires tools and knowledge. Once you move away from that, you are into guessing game and guesses could be wrong. I provided a perfectly good solution: listen to your system with the right material. If you can't hear a distortion then keep what you have. If you do hear the sound change as you increase the volume then you may need a more powerful amp. Can I know or be held responsible for how good your ears are in detecting this? No. For this reason I said you can just buy a powerful amp. If someone wants to make a case that any amplifier is good enough and will not clip, let's see the data on that. I asked for that but nothing has come back

Really, I don't understand this push to sell this formula to everyone when after my first post folks agreed with the issues in it. You can't wave your hands on such things with "it is not 100% so what." These are debating tactics and have no place in a technical discussion. You either know how much it can misfire or not. I have explained in detail. If folks want to put their heads in the sand and use the calculator, be my guest smile.gif. Just don't say you are following "science" when the formula has restrictions and parameters that are exaggerated by marketing departments aiming to sell more speakers.

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post #456 of 637 Old 02-18-2014, 01:15 PM
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Originally Posted by amirm View Post

No. There are things one has to understand not only with the calculator but the numbers you plug into it. Please read my original post a page or so back.

Thats what I mean by "having its limitations". I was referring to the limitations of the whole process and people need to understand them when applying it to what they purchase.

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Originally Posted by amirm View Post

First let set aside any claims where data is not provided. Folks are just selling an opinion however way they can. Recall my first question of how one knows that almost all people have enough amplification. I asked for details on that and there is sound of crickets smile.gif.

You probably received crickets because most in this discussion agree with that opinion based on their own experience and what they've read and researched, including myself.

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Originally Posted by amirm View Post

For the ones that have data like Arny, I explained how it is important to test at multiple frequencies and angles. I have not seen any data related to that. Think of measuring at 50 Hz for example. What if there is a resonance at that point in your room? That could be as high as 10 to 20 db. The calculator did not take that into account. So if it happens that the the data agrees with the calculator, then it is actually the wrong results by 10 db!

If there is a resonance point at the position, there will be a resonance point at that position no matter how much power you put through the speakers. In addition, most speakers have dips in their response at certain frequencies up to 10db so you could use your argument towards most speakers. See the response curves of 8 pretty highly regarded speakers in this thread. Just about all of them have dips close to 10 db at some point in their response curve.
http://www.hometheatershack.com/forums/two-channel-audio/69421-official-1-000-speaker-evaluation-home-audition-event-results.html

More so, the people who have issues with room related issues would be much better served spending their money on some room treatments than additional watts for their amplifier.

But again, this goes back to understanding the types of measurements you put in and the number of data points you take, etc. Which I agree with you on.
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Originally Posted by amirm View Post

Here is a set of measurements for another purpose but does help in this area:

i-H8n7Nfp-L.png

The measurements are the critical distance or the point at which the direct sound = reflected sounds. Notice how it is highly frequency specific. Another way to read this is that as you move back from the speaker the amount that the level drops is frequency specific.

True.....but this phenomenon will not change not matter how many watts you have running through the speaker, so I don't know what your point is.
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Originally Posted by amirm View Post

I did see Wayne express his experience for the equipment he has tested and I accept that as data point. As I said you can build up experience with one set of speakers and amps and develop a feel for what they do in real rooms.
No, but then again I have not seen anyone buy elephants either. biggrin.gif I don't keep track of who is buying an amp using what. As I explained above, the measurement of SPL relative to the calculator is very complex and subject to many parameters. Your speaker manufacturer may have been honest salesman and given you the right number. Or he could have been like member spkr and lied to you by gaming the sensitivity value to get numbers that throw off your power computations by a factor of 2 or more. Such cheating is common. So if folks are seeing agreement across the board, or more conservative value, then they are measuring things wrong.

So you've never tried the SPL calculator method yourself, or observed anyone use it, yet you come here saying it's not a reliable method? There are several reputable people here who have tried it, and witnessed others try it, and they say that its never failed them. Hmmm........now I see why you brought up something as irrelevant to the conversation as "buying elephants".

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Originally Posted by amirm View Post

No, that is not what I said. I said that professionals build up experience and use that rather than some calculator online with numbers plugged into it that are meaningless often. My builder for example built me a shed. He did not need you to tell him what to use for the walls. From experience he knows the framing he needs for that kind of structure. The Pros can use sophisticated methods like I mentioned (e.g. clip detection) but just like my builder, they have sufficient experience to get the answer much more conveniently.

You know you just basically defined the term "empirical design", right? http://www.merriam-webster.com/dictionary/empirical
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Originally Posted by amirm View Post

As to what consumers need to do, first of all they could get equipment returned. Any retailer here will accept returns. Even Amazon does, sans shipping. So that is not the problem. The problem seems to me that the fact that I point out problems in the methodology, it is my responsibility now to solve the user problem. It is not smile.gif. As I said, the science doesn't owe us simple answers. The only correct answer is to instrument the amplifier to see if it is clipping. That is the right answer and it requires tools and knowledge. Once you move away from that, you are into guessing game and guesses could be wrong. I provided a perfectly good solution: listen to your system with the right material. If you can't hear a distortion then keep what you have. If you do hear the sound change as you increase the volume then you may need a more powerful amp. Can I know or be held responsible for how good your ears are in detecting this? No. For this reason I said you can just buy a powerful amp. If someone wants to make a case that any amplifier is good enough and will not clip, let's see the data on that. I asked for that but nothing has come back

Really, I don't understand this push to sell this formula to everyone when after my first post folks agreed with the issues in it. You can't wave your hands on such things with "it is not 100% so what." These are debating tactics and have no place in a technical discussion. You either know how much it can misfire or not. I have explained in detail. If folks want to put their heads in the sand and use the calculator, be my guest smile.gif. Just don't say you are following "science" when the formula has restrictions and parameters that are exaggerated by marketing departments aiming to sell more speakers.

The push is so that people don't get caught up in the hype of "buy as much power as you can afford" because for 95% of people thats a complete waste of money. It gives people a starting point of how much they should spend on amplification so they can allocate more money for speakers, room treatments, speaker mounts that pass the WAF factor, etc. These types of things are all much better bang for the buck purchases than extra watts per channel that will never be used.
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post #457 of 637 Old 02-18-2014, 01:33 PM
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I suspect that the use of SPL calculators that has been encouraged around here has disappointed more salesmen then audiophiles!
Indeed, the primary value of these calculators is that they give you some other data point besides what some #$%^&%$ audio salesman tells you.

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post #458 of 637 Old 02-18-2014, 01:47 PM
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Originally Posted by kgallerie View Post

Thats what I mean by "having its limitations". I was referring to the limitations of the whole process and people need to understand them when applying it to what they purchase.
Yes people need to understand. And that is what I provided: what those limitations are. You seem to be implying that everyone knew this. On what basis are you saying that? Can you explain how the sensitivity number can be gamed for example by speaker manufacturers?
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You probably received crickets because most in this discussion agree with that opinion based on their own experience and what they've read and researched, including myself.
It would be great if the answers were based on research, what they have read, experience, etc. But I highly doubt they are more than repeating company lines. Here is a question that remains unanswered that I referred to:
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Originally Posted by mcnarus View Post

Well, I can tell you where it leaves this consumer—perfectly happy to ignore the whole question. Granted, there are always cases where a particular amplifier won't be able to drive a particular set of speakers at a particular level desired by the consumer. But this situation is extremely rare today.

I asked for data on this. None has come back. You honestly want to vouch for the person making this wide ranging statement to have had the experience and research in this area? On what basis?
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If there is a resonance point at the position, there will be a resonance point at that position no matter how much power you put through the speakers.
I will say it again since the point is missed. The room response in bass is highly variable. You could have +- 15 db of response variations. Anyone who says they have tested these frequencies and managed to match it to a calculator which assumes flat response could not have arrived at the right data.
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So you've never tried the SPL calculator method yourself, or observed anyone use it, yet you come here saying it's not a reliable method? There are several reputable people here who have tried it, and witnessed others try it, and they say that its never failed them.
I am a data driven guy. And I expect tests to be precise before claims are accepted. There are folks who say speaker cables sound different. If I respect them, you are going to believe that statement? Explain the science. Provide data. Provide research. I am the only one providing that. I am not saying the few data points that people may have is wrong. If you want to believe them, fine. But that is not convincing to me. Again, you show me how the sensitivity number can be gamed and we can continue.
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The push is so that people don't get caught up in the hype of "buy as much power as you can afford" because for 95% of people thats a complete waste of money. It gives people a starting point of how much they should spend on amplification so they can allocate more money for speakers, room treatments, speaker mounts that pass the WAF factor, etc. These types of things are all much better bang for the buck purchases than extra watts per channel that will never be used.
Now you are making that claim: please show me data that led you to believe it is 95%, not 90%, not 80%, not 50%. As I said, it is none of your or my business what these things cost. I am here to explain the engineering and science transparently and let the reader decide what to do. If they want to use their coffee money to buy a better amp they can. Or they can keep drinking fancy coffee biggrin.gif. It is a hobby and you can decide what it is worth to you. If you have data that shows the power "will never get used" then let's see that. Otherwise it reads like a campaign line to convert someone to a religion. Be specific with your statements please.

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post #459 of 637 Old 02-18-2014, 01:55 PM
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Originally Posted by mcnarus View Post

Indeed, the primary value of these calculators is that they give you some other data point besides what some #$%^&%$ audio salesman tells you.
Not really. The calculators are used by folks like yourself to make paper arguments, not realizing how the system really works and the fallibility of the data plugged into it. Either you know the problems with it and didn't volunteer them. Or didn't know them and now prefer to block your ears. Neither puts you in good light and makes you look like someone trying to sell a message at all costs. This is how science gets a bad name and people just ignore everything to do with it. We lack transparency. And even when transparency is provided, we resort to off-topic posts like what you are saying. Which salesman have you run into that has explained what I have explained? And if so, what makes you smarter than them?

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post #460 of 637 Old 02-18-2014, 02:07 PM
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Originally Posted by amirm View Post

Yes people need to understand. And that is what I provided: what those limitations are. You seem to be implying that everyone knew this. On what basis are you saying that? Can you explain how the sensitivity number can be gamed for example by speaker manufacturers?
It would be great if the answers were based on research, what they have read, experience, etc. But I highly doubt they are more than repeating company lines. Here is a question that remains unanswered that I referred to:
I asked for data on this. None has come back. You honestly want to vouch for the person making this wide ranging statement to have had the experience and research in this area? On what basis?
I will say it again since the point is missed. The room response in bass is highly variable. You could have +- 15 db of response variations. Anyone who says they have tested these frequencies and managed to match it to a calculator which assumes flat response could not have arrived at the right data.
I am a data driven guy. And I expect tests to be precise before claims are accepted. There are folks who say speaker cables sound different. If I respect them, you are going to believe that statement? Explain the science. Provide data. Provide research. I am the only one providing that. I am not saying the few data points that people may have is wrong. If you want to believe them, fine. But that is not convincing to me. Again, you show me how the sensitivity number can be gamed and we can continue.

Now you are making that claim: please show me data that led you to believe it is 95%, not 90%, not 80%, not 50%. As I said, it is none of your or my business what these things cost. I am here to explain the engineering and science transparently and let the reader decide what to do. If they want to use their coffee money to buy a better amp they can. Or they can keep drinking fancy coffee biggrin.gif. It is a hobby and you can decide what it is worth to you. If you have data that shows the power "will never get used" then let's see that. Otherwise it reads like a campaign line to convert someone to a religion. Be specific with your statements please.

This whole conversation is going no where. As an engineer, I am 1000% for data. In fact, I am the one typically in your shoes in some political threads I occasionally participate in on another forum where I use numbers and data to portray my points. However, on this topic, we have established in this thread that the general consumer has 3 methods to choose the wattage of their amps: 1) spend 5 minutes using an SPL calculator to get an estimated wattage, purchase an amp based on those recommendations or even bump them up a little, then listen and confirm that the calculator was correct or not and increase wattage as required 2) Choose a wattage at random, buy and amp, and then listen and confirm whether the random choice was correct or not, and increase wattage as required or 3) Automatically spend a buttload of $ on the biggest amp you can afford.

Of those 3 options, I'll pick 1 every time.

You are great at throwing stones at the SPL calculator, but your other suggestions are no better.

edit: and to make you happy I will rephrase my statement..........The push is so that people don't get caught up in the hype of "buy as much power as you can afford". From what I have read and my own personal experience, its my opinion that for about 95% of people, that method of choosing an amp a complete waste of money.
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post #461 of 637 Old 02-18-2014, 02:09 PM
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Not really.
No, really.

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post #462 of 637 Old 02-18-2014, 02:11 PM
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However, on this topic, we have established in this thread that the general consumer has 3 methods to choose the wattage of their amps: 1) use an SPL calculator to get an estimated wattage, purchase an amp based on those recommendation, then listen and confirm that the calculator was correct or not and increase wattage as required 2) Choose a wattage at random, buy and amp, and then listen and confirm whether the random choice was correct or not, and increase wattage as required or 3) Automatically spend a buttload of $ on the biggest amp you can afford.

Of those 3 options, I'll pick 1 every time.
I kinda like option 2. smile.gif

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post #463 of 637 Old 02-18-2014, 02:36 PM
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Originally Posted by kgallerie View Post

This whole conversation is going no where. As an engineer, I am 1000% for data. In fact, I am the one typically in your shoes in some political threads I occasionally participate in on another forum where I use numbers and data to portray my points. However, on this topic, we have established in this thread that the general consumer has 3 methods to choose the wattage of their amps: 1) spend 5 minutes using an SPL calculator to get an estimated wattage, purchase an amp based on those recommendations or even bump them up a little, then listen and confirm that the calculator was correct or not and increase wattage as required 2) Choose a wattage at random, buy and amp, and then listen and confirm whether the random choice was correct or not, and increase wattage as required or 3) Automatically spend a buttload of $ on the biggest amp you can afford.
The conversation does not get anywhere because you keep modifying what I have said. Here it is again in the original post:
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Originally Posted by amirm View Post

Answering your larger question, I think i mentioned my philosophy before. You can do two things:

1. Play a very dynamic track, e.g. something with heavy bass notes. I have this CD that I got from the speaker company Usher that has these oriental drums in it that make fantastic test track. Unfortunately it is not a commercial CD and they only give it away at shows. But maybe you can find something similar. Start at low volume and keep turning it up. Listen to the balance of the bass notes vs the rest. Does the bass weaken at some point? If so, and this is still not as loud as you can tolerate, then you lack sufficient amplification in your current system.

2. Buy as much amplification as you can afford and be done with it smile.gif.

Where is option #1 in mine in your list? Instead you rather trust a formula that you don't know its basis and whose data is faulty?

You say as an engineer you are 1000% for data but your posts don't provide any. I asked you to explain the key parameter used in that calculator: speaker efficiency. Do you know how that is computed? Changing that number by 3 will change the power requirement by a factor of 2. No small amount. But really, I have said all of this before and the only counter is back to "I don't want to see people spend money on electronics." I keep providing technical explanations and data and you keep providing layman arguments.

So let's do a layman argument. Assume you are in a forum that is about structural engineering -- your expertise and profession. I come there with no work experience or degree in that regard. But I have read stuff online and someone says I design this truss using a formula. I mention that in a thread and you come back and say, "wait a minute...that formula can easily give you the wrong answer because of X, Y and Z reasons." It could happen right? Surely me as a forum reader would never have the depth of your experience and knowledge to do what you do. You explain your reasoning with data, science, etc. And that I likely need a stronger truss than I think. How do you feel about me coming back and accusing of wanting to make members spend more money? And that the formula is good enough. How many rounds would you go with me in that regard? Can you answer that?
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Of those 3 options, I'll pick 1 every time.
No problem.
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You are great at throwing stones at the SPL calculator, but your other suggestions are no better.
No, my suggestion of doing a listening test is far better than a dumb calculator used with marketing numbers as its key parameter. Or buy a scope on ebay, learn how an amplifier works and instrument whether it is reaching its maximum power. Failing either, no I would not tell you to use a calculator that can give you numbers that can be off by a factor of 2 or more. Per my question above, would you suggest that I use a formula that gives me that kind of accuracy error in your line of work?
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edit: and to make you happy I will rephrase my statement..........The push is so that people don't get caught up in the hype of "buy as much power as you can afford". From what I have read and my own personal experience, its my opinion that for about 95% of people, that method of choosing an amp a complete waste of money.
What makes me happy is if you listen to explanation of this technology and not keep twisting my position as to convince people your opinion is right wink.gifsmile.gif.

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post #464 of 637 Old 02-18-2014, 02:52 PM
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The conversation does not get anywhere because you keep modifying what I have said. Here it is again in the original post:
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Originally Posted by amirm

Answering your larger question, I think i mentioned my philosophy before. You can do two things:

1. Play a very dynamic track, e.g. something with heavy bass notes. I have this CD that I got from the speaker company Usher that has these oriental drums in it that make fantastic test track. Unfortunately it is not a commercial CD and they only give it away at shows. But maybe you can find something similar. Start at low volume and keep turning it up. Listen to the balance of the bass notes vs the rest. Does the bass weaken at some point? If so, and this is still not as loud as you can tolerate, then you lack sufficient amplification in your current system.
Right. So that's essentially option 2. The only purpose of an SPL calculator is to give one a place to start.

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post #465 of 637 Old 02-18-2014, 02:53 PM
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The conversation does not get anywhere because you keep modifying what I have said. Here it is again in the original post:
Where is option #1 in mine in your list? Instead you rather trust a formula that you don't know its basis and whose data is faulty?

That option you provided in #2 in my list. How will someone listen to an amp in their own home prior to purchasing? Like I said, using the SPL calculator is a 5 minute exercise to give you a starting point. Then once you purchase an amp, your option #1 is a great way to test it out once you purchase an amp.

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Originally Posted by amirm View Post

You say as an engineer you are 1000% for data but your posts don't provide any. I asked you to explain the key parameter used in that calculator: speaker efficiency. Do you know how that is computed? Changing that number by 3 will change the power requirement by a factor of 2. No small amount. But really, I have said all of this before and the only counter is back to "I don't want to see people spend money on electronics." I keep providing technical explanations and data and you keep providing layman arguments.

So let's do a layman argument. Assume you are in a forum that is about structural engineering -- your expertise and profession. I come there with no work experience or degree in that regard. But I have read stuff online and someone says I design this truss using a formula. I mention that in a thread and you come back and say, "wait a minute...that formula can easily give you the wrong answer because of X, Y and Z reasons." It could happen right? Surely me as a forum reader would never have the depth of your experience and knowledge to do what you do. You explain your reasoning with data, science, etc. And that I likely need a stronger truss than I think. How do you feel about me coming back and accusing of wanting to make members spend more money? And that the formula is good enough. How many rounds would you go with me in that regard? Can you answer that?

No problem.

No, my suggestion of doing a listening test is far better than a dumb calculator used with marketing numbers as its key parameter. Or buy a scope on ebay, learn how an amplifier works and instrument whether it is reaching its maximum power. Failing either, no I would not tell you to use a calculator that can give you numbers that can be off by a factor of 2 or more. Per my question above, would you suggest that I use a formula that gives me that kind of accuracy error in your line of work?
What makes me happy is if you listen to explanation of this technology and not keep twisting my position as to convince people your opinion is right wink.gifsmile.gif.

Your suggestion of doing a listening test is useless if you don't have an amp yet to listen too. Since you can't listen to an amp you don't have, your next suggestion is to buy as many watts as possible, which I don't agree with. I'll spend 5 minutes plugging a few numbers into a calculator that many people have used successfully with positive results to avoid spending all that I can afford if I don't need it. Worst case, I then do your listening test to determine if its enough power and may need to upgrade. But based on my empirical judgement of all of those who have been happy with the results of the SPL calculator, it seems like an effective tool to find a starting place.

Just to humor you with your structural engineering forum question, I would show them why the formulas they have is incorrect. Then I would proceed to tell them the correct formula and the correct procedure to solve their problem. If they aren't capable of following and understanding the full technical solution, I would direct them to a shorter, simpler, and more practical way to estimate the answer. Being a common guy who's likely doing DIY house work, an estimate is likely enough detail for what he is doing.
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post #466 of 637 Old 02-18-2014, 03:14 PM
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Right. So that's essentially option 2. The only purpose of an SPL calculator is to give one a place to start.
No, the option is exactly as I listed it. It didn't require rewrite using words like "random." There was nothing random about it. It was a thought out process based on experience and what ultimately matters: whether you hear distortion or not.

If you have an existing system which I assume anyone here already does, then you start with that. If it has no distortion then you are done and didnt' waste time with any make-belief calculator. If it has distortion, then you go shopping for a higher power unit. If you are shopping for a premium system see if the dealer will let you take the gear home prior to purchasing. Many will let you do that. If so, take it home and do your test again. If the distortion is gone then the job is done. If they don't loan you gear, buy it on credit card, listen and if it doesn't perform yet, then take it back. If the store does not take returns, shop elsewhere.

If you don't have a system right now, then you can listen in the store and run the same test. That gives you a far better "starting point" than any dumb calculator.

Any chance you would answer the questions I asked you?

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post #467 of 637 Old 02-18-2014, 03:20 PM
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Originally Posted by kgallerie View Post

Just to humor you with your structural engineering forum question, I would show them why the formulas they have is incorrect. Then I would proceed to tell them the correct formula and the correct procedure to solve their problem. If they aren't capable of following and understanding the full technical solution, I would direct them to a shorter, simpler, and more practical way to estimate the answer. Being a common guy who's likely doing DIY house work, an estimate is likely enough detail for what he is doing.
And if they keep arguing with you in post after post that your redirected answer is wrong and they were right because "the people they trust use it and say it works" then what? Are you right or are they?

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post #468 of 637 Old 02-18-2014, 03:21 PM
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No, the option is exactly as I listed it. It didn't require rewrite using words like "random." There was nothing random about it. It was a thought out process based on experience and what ultimately matters: whether you hear distortion or not.

If you have an existing system which I assume anyone here already does, then you start with that. If it has no distortion then you are done and didnt' waste time with any make-belief calculator. If it has distortion, then you go shopping for a higher power unit. If you are shopping for a premium system see if the dealer will let you take the gear home prior to purchasing. Many will let you do that. If so, take it home and do your test again. If the distortion is gone then the job is done. If they don't loan you gear, buy it on credit card, listen and if it doesn't perform yet, then take it back. If the store does not take returns, shop elsewhere.

If you don't have a system right now, then you can listen in the store and run the same test. That gives you a far better "starting point" than any dumb calculator.

Any chance you would answer the questions I asked you?

Ok.....so say I perform your listening test to my existing 50w/channel receiver and I find that its underpowered. Now what? Either I 1) plug some numbers into the SPL calculator to see what my next step up should be 2) i choose randomly what next level I should try or 3) I spend all that I can afford immediately. Again.....I'll choose option 1.
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post #469 of 637 Old 02-18-2014, 03:27 PM
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And if they keep arguing with you in post after post that your redirected answer is wrong and they were right because "the people they trust use it and say it works" then what? Are you right or are they?

I've only had 2 points of contention with all that you have said:

1) People should listen to an amp they haven't yet purchased, which is impossible unless of course they go to a high end audio store to try demo units.
2) That people should spend all that they can afford on watts.

I never said you were incorrect on any of your contentions regarding the accuracy of the SPL calculators.

For the 1,000th time, the SPL calculators are to determine a starting point for the general consumer, and nothing more. From there, its all up to the ears of the listener. Can we at least agree on this?
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post #470 of 637 Old 02-18-2014, 04:28 PM
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Originally Posted by mcnarus View Post

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The conversation does not get anywhere because you keep modifying what I have said. Here it is again in the original post:
Quote:
Quote:
Originally Posted by amirm

Answering your larger question, I think i mentioned my philosophy before. You can do two things:

1. Play a very dynamic track, e.g. something with heavy bass notes. I have this CD that I got from the speaker company Usher that has these oriental drums in it that make fantastic test track. Unfortunately it is not a commercial CD and they only give it away at shows. But maybe you can find something similar. Start at low volume and keep turning it up. Listen to the balance of the bass notes vs the rest. Does the bass weaken at some point? If so, and this is still not as loud as you can tolerate, then you lack sufficient amplification in your current system.
Right. So that's essentially option 2. The only purpose of an SPL calculator is to give one a place to start.

Looks like an attempt to shift from an objective criteria - the SPL calculator to a subjective one, and a questionable subjective criteria at that because the idea that an amp that is running out of power starts weakening in the bass is speculation. To turn it from speculation to reliable evidence it would be necessary to see whether pushing an amp into clipping actually weakens the bass. I can think of reason why it won't, not to mention the issue that follows.

Here is the other issue. Most serious audiophiles have subwoofers. It is primarily the subwoofer that carries the strength of the bass notes, not the AVR. So, there's a second problem with the proposed subjective approach, it may not even be a test of the power amps in the AVR. It could and most likely a test of some other part of the system than the AVR.
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post #471 of 637 Old 02-18-2014, 05:27 PM
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Originally Posted by arnyk View Post

Looks like an attempt to shift from an objective criteria - the SPL calculator to a subjective one, and a questionable subjective criteria at that because the idea that an amp that is running out of power starts weakening in the bass is speculation. To turn it from speculation to reliable evidence it would be necessary to see whether pushing an amp into clipping actually weakens the bass. I can think of reason why it won't, not to mention the issue that follows.
Interesting comment. Earlier I quoted the Rane article:
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Originally Posted by amirm View Post

Remember that the so called "clipping" sound is not what you will hear in home stereos. Your clock radio "clips." Your home stereo will compress dynamics well before it gets to the kind of distortion that is called "clipping." Here is another reference saying the same thing: http://www.rane.com/pdf/old/note128.pdf

"Power amplifier clipping is quite common. This note examines the clipping phenomenon which allegedly damages loudspeakers. We suggest that this form of distortion is not the cause. Rather, we show that amplitude compression of the audio spectrum is the culprit. Rane limiters provide a solution to amplitude compression, thus preventing loudspeaker failure.

[...]

It may be argued that the signal’s distortion would be intolerable. Don’t fool yourself. It really surprises people how much clipping they tolerate before they cannot listen anymore. Just disconnect the clipping indicator on a power amplifier and see how loud someone drives it. Watch the amplifier output with an oscilloscope. There will be a surprising level of clipping. 10 dB clipped off the top of low frequency transients is not an uncommon occurrence when the purpose is to impress your neighbors."


We discussed the very article a week or two ago. There you said this:
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Originally Posted by arnyk View Post

I hope nobody remains confused by the mistaken conclusion that there are errors in the Rane paper on clipping.

The rane article clearly makes a case for amplitude compression of bass frequencies. Isn't that what you agreed with in the other thread? And how about the comment in the article saying " Power amplifier clipping is *quite* common?"

That aside, objective goals need to be correct. Ever hear the expression garbage in, garbage out? By your metric any formula I cook up, regardless of how wrong it is, is preferable because it is "objective." And no, there is no "speculation here." I have already mentioned how the sensitivity number can be gamed. I thought you agreed with that. No?
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Here is the other issue. Most serious audiophiles have subwoofers. It is primarily the subwoofer that carries the strength of the bass notes, not the AVR. So, there's a second problem with the proposed subjective approach, it may not even be a test of the power amps in the AVR. It could and most likely a test of some other part of the system than the AVR.
Most serious "audiophiles" do NOT have subwoofers. They have full range speakers. Most home theater users have subs. Some AVRs like the Sony I tested do not allow bass management in their pure stereo mode. So even there we have restrictions.

The discussion here is about amplification. If a person has issues with their subs, I am sure they will indicate so.

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post #472 of 637 Old 02-18-2014, 05:34 PM
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For the 1,000th time, the SPL calculators are to determine a starting point for the general consumer, and nothing more. From there, its all up to the ears of the listener. Can we at least agree on this?
And for the 1,000th time, no smile.gif. There is no "starting point: when you really don't know one of the key parameters to plug into the calculator: speaker sensitivity.

Here is what the preface to the calculator says:

"The speaker sensitivity, typically expressed in decibels (dB) with 1 watt (or 2.83 volts across an 8 ohm speaker) measured on-axis one meter away."

Do you know what that means? If not, how do you blindly plug in numbers in there?

By the way, what do you do when you upgrade your speakers and it has lower sensitivity? Go buy yet another amp??? You see why I said buy the most powerful amp you can?

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post #473 of 637 Old 02-18-2014, 10:12 PM
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So many years and trade shows have gone by. We've used low power tube amps and low power solid state class A designs with huge power supplies thru very high power 500 watt and up mono amps, in all sorts of settings, loudspeakers, and rooms. In the end, if you do not wish to limit your ability to play a wide variety of music (and BTW I completely understand high quality low power amps for what they do best), in the end you need lots of power.

Put another way, nothing schools you like playing a track and having an instrument distort because the system ran out of steam. I've found 200 watts @ 8 ohms, and as close to a clean double 400 watts into 4 ohms as you can get to be minimum amplification with a typical efficiency full range loudspeaker.

Go big or go home...
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post #474 of 637 Old 02-19-2014, 05:26 AM
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Originally Posted by amirm View Post

And for the 1,000th time, no smile.gif. There is no "starting point: when you really don't know one of the key parameters to plug into the calculator: speaker sensitivity.

LOL.....now you're just being stubborn. So tell me.....if you were to start a new system in a new room at your house, how would you decide what cost effective amp you would choose to first try out?
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Here is what the preface to the calculator says:

"The speaker sensitivity, typically expressed in decibels (dB) with 1 watt (or 2.83 volts across an 8 ohm speaker) measured on-axis one meter away."

Do you know what that means? If not, how do you blindly plug in numbers in there?

By the way, what do you do when you upgrade your speakers and it has lower sensitivity? Go buy yet another amp??? You see why I said buy the most powerful amp you can?

Yes, I understand what sensitivity is and what it means, and I understand that there are many ways that speaker manufacturer's can fudge that number, but again, its an estimate, a first guess, a point in the right direction. What don't you understand about that? Many amp/receiver manufacturer's fudge power data too, but you still look at the specs when you decide what amp to buy.

If you want to future proof your amp in case you buy different speakers down the road, put in a conservative number. I think the lowest sensitivity I've seen listed on a speaker is about 85db, so when you use the calculator input 84 or 83db. But thats a decision make by the person using the calculator. That goes along with understanding the info you are putting in to the SPL.

You really are grasping at straws here trying to discredit a 5 minute exercise to give you an idea of the power you should consider in an amp. Your citing instances that might not work out once in a blue moon (no I don't have a data confirming that), when numerous people have used that method with great success.

Its almost like you have some special interest in talking people into buying much larger equipment than they need...... wink.gif
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post #475 of 637 Old 02-19-2014, 05:31 AM
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Originally Posted by Joe Skubinski View Post

So many years and trade shows have gone by. We've used low power tube amps and low power solid state class A designs with huge power supplies thru very high power 500 watt and up mono amps, in all sorts of settings, loudspeakers, and rooms. In the end, if you do not wish to limit your ability to play a wide variety of music (and BTW I completely understand high quality low power amps for what they do best), in the end you need lots of power.

Put another way, nothing schools you like playing a track and having an instrument distort because the system ran out of steam. I've found 200 watts @ 8 ohms, and as close to a clean double 400 watts into 4 ohms as you can get to be minimum amplification with a typical efficiency full range loudspeaker.

Go big or go home...

Can you please quantify these statements a bit? What settings (room sizes, speakers, and amps) you were using when the system "ran out of steam"? Have you ever had an amp "run out of steam" in a standard size living room with decent, reputable equipment? If so, can you please elaborate on the specs in that situation too?
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post #476 of 637 Old 02-19-2014, 06:25 AM
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Its almost like you have some special interest in talking people into buying much larger equipment than they need...... wink.gif
My interest is what I said before: transparency in explaining the technology. I don't paper over the cracks because it might aid someone to make another argument. Until I post, none of the issues with the calculator were stated. I listed them and all of a sudden a lot of resistance ensued including the type of personal remarks you are using. None of the people complaining have provided any more data, insight, or explanation of technology. As you, it is just stomping one's feet that they are right to use the calculator.

Answering anyway, amplifiers do not become obsolete like some other components such as AVRs. It pays to buy the right one and be done with it. I still have my first amplifier I bought 30 years ago! It was a beefy unit with independent power supplies and works like a champ even today. The second Amp I bought was multi-channel and I have had that for 10+ years. In contrast, I have gone through half a dozen processors and AVRs in that same decade. When I built my new theater, I put my multi-channel amp in there without a worry or relying on some dumb calculator. You want to buy cheap? You will buy again.

Now, not everyone can afford better quality/higher power amps. Nor do they need it. I provided the best method to determine if the amp is a good fit for you:: listen to the amp. Somehow you are putting more trust in a calculator than your ears. The calculator says nothing about the performance of the amplifier with your speakers. Like other factors, it assumes perfection. This is why you want to listen. I have listened to countless amplifiers and systems. You have listened to how many permutations?

Another thing you will learn about me: I get bored discussing topics with someone when they are not adding anything new to the topic. People are here to learn about technology. If half a dozen interchange between us is just stomping feet that you are right, then there is no learning there. If you like to post again to say you are right, you are welcome to do so. But I may not answer anymore. I hope you understand smile.gif.

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post #477 of 637 Old 02-19-2014, 06:46 AM
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Originally Posted by kgallerie View Post

For the 1,000th time, the SPL calculators are to determine a starting point for the general consumer, and nothing more. From there, its all up to the ears of the listener. Can we at least agree on this?
And for the 1,000th time, no smile.gif. There is no "starting point: when you really don't know one of the key parameters to plug into the calculator: speaker sensitivity.

Here is what the preface to the calculator says:

"The speaker sensitivity, typically expressed in decibels (dB) with 1 watt (or 2.83 volts across an 8 ohm speaker) measured on-axis one meter away."

Do you know what that means? If not, how do you blindly plug in numbers in there?

Don't be insulting Amir! Just because we take those numbers with a grain of salt but still use them doesn't mean that any of us are that ignorant!

I get this feeling that some of us are more familiar with real world engineering than others. Absent, proprietary and not for you, bogus and questionable performance numbers from component suppliers is one of the reasons why audio engineering is both an art and a science. ;-) Amazingly large and effective systems get built in this environment, regardless.
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By the way, what do you do when you upgrade your speakers and it has lower sensitivity?

I am then thankful that my Peak SPL calculator runs a bit pessimistic and/or that I took the numbers with a grain of salt and bought the next biggest amp in the amp vendor's product line.
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Go buy yet another amp??? You see why I said buy the most powerful amp you can?

I believe that by sluffing post 433 - http://www.avsforum.com/t/1485846/quality-power/420#post_24373422 there was a tacit admission that we are in another one of those "Do as I say, don't do as I do" situations. ;-)
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post #478 of 637 Old 02-19-2014, 06:58 AM
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My interest is what I said before: transparency in explaining the technology. I don't paper over the cracks because it might aid someone to make another argument. Until I post, none of the issues with the calculator were stated. I listed them and all of a sudden a lot of resistance ensued including the type of personal remarks you are using. None of the people complaining have provided any more data, insight, or explanation of technology. As you, it is just stomping one's feet that they are right to use the calculator.

You were right to post the limitations and the things people need to consider when using the calculator. But you went far beyond that by saying the calculator is useless. That is not true. It simply gives you a starting point to determine the minimum power you should be considering and eliminates several of the listening trial an error iterations that you recommend .
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Answering anyway, amplifiers do not become obsolete like some other components such as AVRs. It pays to buy the right one and be done with it. I still have my first amplifier I bought 30 years ago! It was a beefy unit with independent power supplies and works like a champ even today. The second Amp I bought was multi-channel and I have had that for 10+ years. In contrast, I have gone through half a dozen processors and AVRs in that same decade. When I built my new theater, I put my multi-channel amp in there without a worry or relying on some dumb calculator. You want to buy cheap? You will buy again.

I agree with this accept for the last statement of "You want to buy cheap? You will buy again". Of course the term "cheap" is relative, however I bought an emotiva UPA-200 for $200 on craigslist, and I will likely never replace it. Hell, I bought a Denon dra-635 from craigslist for $75 (80w/ch) and that was more than enough power. I definitely didn't need to upgrade to the UPA-200 for external amplification, but i got the itch because of people who say "buy more power" and "external amplification is better". So I bought the UPA and notice just about zero difference. I kept the UPA though or its ability to drive lower impedance speakers incase I upgrade or have the change to try out some lower impedance speakers. Both of these items were relatively "cheap" when it comes to home audio, and they are both more than capable for my needs.
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Now, not everyone can afford better quality/higher power amps. Nor do they need it. I provided the best method to determine if the amp is a good fit for you:: listen to the amp. Somehow you are putting more trust in a calculator than your ears. The calculator says nothing about the performance of the amplifier with your speakers. Like other factors, it assumes perfection. This is why you want to listen. I have listened to countless amplifiers and systems. You have listened to how many permutations?

Again, you are ignoring the point that you can't listen to an amp you don't have. Thats pretty plain and simple and a cold, hard fact. The SPL calculator will help eliminate some of the iterations in your trial and error listening method. Once you've used the SPL calculator and have an amp, I agree that listening is the best way to measure.
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Another thing you will learn about me: I get bored discussing topics with someone when they are not adding anything new to the topic. People are here to learn about technology. If half a dozen interchange between us is just stomping feet that you are right, then there is no learning there. If you like to post again to say you are right, you are welcome to do so. But I may not answer anymore. I hope you understand smile.gif.

Thats fine. I agree we are going in circles, but please recognize you are doing your share of feet stomping too. You keep saying use your ears to determine if your amp is adequate. So you can have all the fun you want listening to the amp in your room when there is no amp in your room to listen too. You probably wont have too many friends joining you in that audio experience.
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post #479 of 637 Old 02-19-2014, 07:11 AM
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Originally Posted by arnyk View Post

I get this feeling that some of us are more familiar with real world engineering than others. Absent, proprietary and not for you, bogus and questionable performance numbers from component suppliers is one of the reasons why audio engineering is both an art and a science. ;-) Amazingly large and effective systems get built in this environment, regardless.
And none of that "art" is embedded in that calculator! Nor any real life experience. It is a formula based on idealistic assumptions that don't even include your room. Worse yet, it uses numbers that you as an end user, have no way of verifying to be correct.

My real life experience says sensitivity numbers are just plain wrong. I once had an amplifier noise with these high efficiency speakers. Naturally I assumed it was due to the high sensitivity of the speakers that I could hear it and there was no fault of the amp. But just to be sure, I plugged the amp into another speaker that had sensitivity that was nearly 10 db lower. Guess what? The exact amount of noise remained! I swapped amplifiers with a higher fidelity one and I went from hearing the noise from 3-5 feet to 2-3 *inches* in front of the tweeter. Does your calculator predict that? I don't think so.

So yes, experience matters and matters a lot. When you have access to countless pieces of equipment on daily basis, you get to run experiments that end user simply cannot. Reading forum posts and online stuff only gets you so far.

Your doctor forever will know more about medicine than you no matter what you read online. I had my doctor prescribe a new medicine and I started to have some other symptoms. I explained that to him and he said that was very unusual and not one that is likely to be due to the medication. Believing otherwise, I went online and found the list of side effects for that medication from the manufacturer and what do you know, it showed my exact symptom as one of the side effects in their patient studies!!! I go to my next visit with my doctor and tell him that I was right about this being a side effect. He asked me how I found out. I said that I read it in the patient studies. He calmly explained that when the studies are done, whatever people report is documented and reported. If two people get muscle ache, they list them. But there is no telling that symptom is due to the medication. He said the real data is from doctors who prescribe the same medication hundreds of times and based on that, they learn what are the likely symptoms. Fast forward a couple of months and I found the cause for my secondary symptoms and had nothing to do with the medication! I learned to not challenge my doctor this way smile.gif.

So yes, experience matters and matters a lot. I have repeatedly asked how large of a data set you all have in ascertaining the efficacy of this formula. No one has answered. Or provide any specifics. Given that, the data must not exist or be convincing. Yet being put forward to counter real life experience that I have.
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I am then thankful that my Peak SPL calculator runs a bit pessimistic and/or that I took the numbers with a grain of salt and bought the next biggest amp in the amp vendor's product line.
As I mentioned to you, you did not really measure the SPL in your room. SPL in your room is frequency, and angle dependent among other things like how close speakers are to walls and such. That you got one sample point that was 2 db different means nothing when you need to have hundreds of points to make a determination.

The real question is, did the amp clip when you turned it up as loud as you could. If it did not, it mattered not what the dumb meter said. You have no problem. But if it distorted, then you do have a problem but once more, it matters not what the dumb meter or the formula spit out. You need a more powerful amp. Or at least one that is better designed with more of that "art" in it.
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I believe that by sluffing post 433 - http://www.avsforum.com/t/1485846/quality-power/420#post_24373422 there was a tacit admission that we are in another one of those "Do as I say, don't do as I do" situations. ;-)
Seems like you didn't read my answer to you in this post: http://www.avsforum.com/t/1485846/quality-power/420#post_24373940. As you see there, I gathered far more data than you did and still that was not enough to characterize the SPL in that room. And I linked to a post on Gearslutz with even more data. So no, I do have data and importantly understand the complexity of the matter which cannot be trivialized in one measurement with no specifics provided whatsoever.

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post #480 of 637 Old 02-19-2014, 07:46 AM
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Originally Posted by amirm View Post

So yes, experience matters and matters a lot. I have repeatedly asked how large of a data set you all have in ascertaining the efficacy of this formula. No one has answered. Or provide any specifics. Given that, the data must not exist or be convincing. Yet being put forward to counter real life experience that I have.

LOL.....many here have stated that they have been happy with the results of using the SPL calculator and that their amp selection based on the SPL calculator was more than adequate. Each of those are a data point.

When I asked you how many people you have heard of that found the SPL calculator inadequate, you said zero. So it sounds like we have a whole lot more empirical data points backing up the effectiveness of the calculator than you do countering it. These are empirical data points, so the likelihood of incorrect posted speaker sensitivity was included in these tests.
Quote:
Originally Posted by amirm View Post

As I mentioned to you, you did not really measure the SPL in your room. SPL in your room is frequency, and angle dependent among other things like how close speakers are to walls and such. That you got one sample point that was 2 db different means nothing when you need to have hundreds of points to make a determination.

LOL.....this is where you are taking it beyond where it needs to go for the general consumer. If you listen the the speakers at 1 MLP all the time, then the one reading is sufficient at that location. If you want dispersed sound, take a few measurements around the room. But hundreds of measurements? Nobody cares if the music is loud enough for the spider hiding in the upper corner of the room.
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