Getting to Know the Watt!

[F.Cook]

The following (attachment) is from Part 1 of a 2 Part lecture series that I developed and delivered several years back, relating to consumer amplifier ratings, and basic amplifier measurement.

It was my initial desire to post both parts, however, the files have become corrupted, but luckily I found a backup of the original draft, of Part 1, of the 2008 modified program. The program was originally developed in 2006, if memory serves me correctly, and went through an update in 2008.

Since I only have a copy of the drafted update, some images will be missing (or in the wrong places, or inserted merely as place holders), and there will be a few too many typo's; however, the central theme seems preserved (and I fill in the gaps if asked nicely, have merit and if the answers are not glaringly obvious, from off the pages), and is sufficient enough to be of value to many of the newer audio enthusiasts, in this forum. Those of whom with significant back grounds relating to the topic, will recognize the 101/baby step approach, taken throughout; and as such, will not glean much value from it.

The program was offered as an elective and ran over the coarse of two long evenings. As you will discover, the context is based in the 12-Volt amplification realm; however, 99% of what is presented is directly transferable to all other categories of audio amplification.

It is a 101 entry point; which aims to acclimate the student in the industry nomenclature, and rating standards/culture, as to provide a base for entry into the 201 level's of education. So IMO, I'd say that it's highly readable, and fairly easy to follow.

Lastly, these excerpts are from the student workbook, and are not complete lessons or ideas as such, on their own. The complete education was provided by the in tandem lecture, lab demonstrations and exercises, which I have not included within this post.

I hope that at least a few of you, find the documentation to be of some value.

Download the entire PDF from:

https://www.dropbox.com/home

Email: avforumdownloads@gmail.com
Password: aquafina

PREVIEW





Entire document available for download via Dropbox link noted above...

 

[F.Cook]

I'm sure that it's a lot to read through, sort and think on. So for those of whom that are desiring some assistance, I will be offering a series of additional posts, each growing in inclusions/considerations.



But first, I think it beneficial for me to spell out the central theme, and the origin of the program for you.


Amongst laypeople, much assumption exists, with regards to audio reproduction and the equipment that supports it. As such individuals enter into the market place, with desires toward personally owning a piece of the promised experiences, but they instantly become faced with more options, and related complexities, such that has never existed before, in the history of consumer electronics. It has frankly become, an untenable condition, as there is no clear paths available to traverse, for 'people' at large; to clear, succinct understandings of audio truths. As a result, the market place at large has gravitated to reactionary, uneducated, bombastic presentations of perverted audio truths; with the net result being a purely commoditized market place; lacking in the specialized skill-sets required, to guide consumer to their best options, for their given budget and application. De Facto indication - the internet has become the retail ‘Shopping Mall’ of consumer electronics. We have entered an age of F.A.B shopping (feature, advantage, benefit), and left performance based audition shopping behind. At one time, it was considered reprehensible, to buy a TV, let-alone a hi-fi component of any variety, without auditioning it. How many of us, even knowing better we have succumb to this nonsensical behavior, on at least a few occasions (ignorance is a powerful force). It's absolutely impossible to determine the sonic goodness of any device from manufacturer supplied specifications - period. Taking that statement a step further, it is also impossible to determine such from any online reviewer, as well. All that is available, is a meager ability to provide a responsible sorting of items, as to place them into classes of performance. From such classes, directions may be provided based on budget and application, and not necessarily in that order (from individuals with the appropriate skill-sets - the very skill-sets Power Factory provided).


The program from which these excerpts were taken, was devised in a way to port the requisite educations, to budding audio professionals, in order for them to take up the charge, of becoming appropriately educated/trained consultants, and integrators. A large charge to be sure; however, one met with much eagerness, and appropriate study habits.


The ship being too large, if you will; to turn 360-degrees all at once, forced me to decided to work from within the ship, again, if you will; and work outwardly towards all coordinates. So the Watt being the seeming embodiment of all musical goodness, or lacks there of,was decidedly the best way in to the middle of it all, if you will.


The slogan ‘Getting to Know the Watt’ was coined, and with it the central theme of the two part lecture series (24-hours): Power Factory.


Power Factory, is a name selected due to its De Facto relationship to amplifiers, as they are in fact 'power factories' of varying output potentials. The potentials being governed primarily by the size and quality of their transformers, then secondly, by all other stages and factors of topology and engineering. In other words, small transformer size or count, or both, leads to an amplifier's potential output being intrinsically limited, regardless of the additional factors, which come after (are secondary). Those other factors however, are capable of relegating the potential power delivers of any transformer, to just a meager sum, predicated on the introduction of oscillations, frequency deviations, infestation of noises, and harmonics, not just of a high percentage, but of dissonant accompaniment. These potentially limiting factors, evidence themselves under different conditions, most of which don't develop while being tested, with non-inductive (non-real world loads), and being agitated with short-term frequency bursts, etc., When they do - it's immediately obvious to even the most layperson, as they tend towards being immediately and overtly audible errors. So in order to get to know the Watt, the investigation must progress inward, into the device, past just using the output terminals. However, there is much to be learned from the outputs first. The key is to push the device, into varying loads, for prolonged periods, alongside of performing the cursory measurements, of which 99% of all wood-be regulatory bodies push, as minimum goodness indexes. It's important to understand, that none of them claim to estimate absolute power or make any estimates towards contrasts in sonic goodness’s, which means that they're not of much value, unless you happen to come upon two device, of the same Wattage estimates, which happen to be rated using the same standards and have disclosed complete, reference specifications scores. The odds of which hover around zero!

As mentioned the lecture series contained two parts. In part one, the students were educated in common terminology, relevant mathematical formulas (which I will share in time) and were acclimated in the CEA 2006 amplifier measurement standards (and others), processes, and were provided solid insight into very obvious amplifier short comings and differences, which are clearly visible, even within such a light weight testing metrics.


Ultimately, they quickly learn that in order for an amplifier to be deemed a true power factory that it’s all about pure current production and purity retention! In every Watt, there’s two factor of current and one factor of resistance (more on that truth to come), making power, all about current deliveries, in the face of varying loads (Impedances). It’s that simple – yet ultra-complex to measure to absolutes, as complex varying AC…


Topic 1: for us here in this forum: Analyzing CEA 2006 THD Samples
We will taking our time, so don’t be in rush, we will cover more than you’re likely imagining that we will.

Topic 2:
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[F.Cook]

Okay, let's get started!

PART 1:

Above, are three measurements taken as outlined in the CEA 2006 guidelines, relating to a 1% THD limit. The amplifier is rated by the manufacturer to output 25Wx2 into 4-Ohms; 50Wx2 into 2-Ohms; 100Wx2 into 1-Ohm. @.03%THD @ 1KHz... Our Test was at 100Hz...

1. What color do you think, relates to what load?
a) 4-Ohm:_____
b) 2-Ohm:_____
c) 1-Ohm:_____

2. By looking at the graphs, would you say that it met it's specifications?
a) 4-Ohm:_____
b) 2-Ohm:_____
c) 1-Ohm:_____

3. What would you say the CEA power scores are, by looking at the graph?
a) 4-Ohm:_____
b) 2-Ohm:_____
c) 1-Ohm:_____

4. Using these measurement depictions, what would you say is the true peak power, for each load, before the device enters in to clipping?
a) 4-Ohm:_____
b) 2-Ohm:_____
c) 1-Ohm:_____


PART 2: Above, are three measurements taken as outlined in the CEA 2006 guidelines, relating to a 1% THD limit. The amplifier is rated by the manufacturer to output 25Wx2 into 4-Ohms; 50Wx2 into 2-Ohms; 100Wx2 into 1-Ohm. @.03%THD @ 1KHz... Our Test was at 100Hz...

1. What do you think, the true RMS score is for each load, based on the measurements above?
a) 4-Ohm:_____
b) 2-Ohm:_____
c) 1-Ohm:_____

2. By looking at the graphs, what load would you say performance wise, appears to be the most linear?
a) 4-Ohm:_____
b) 2-Ohm:_____
c) 1-Ohm:_____

3. At what level of THD distortion, for each load, is it clear the that the amplifier has entered into current deficiencies/clipping?
a) 4-Ohm:_____
b) 2-Ohm:_____
c) 1-Ohm:_____

4. Using these measurement depictions, what would you say is the true, usable peak power, for each load?
a) 4-Ohm:_____
b) 2-Ohm:_____
c) 1-Ohm:_____

Next Part 3:

Above, are three measurements taken as outlined in the CEA 2006 guidelines, relating to a 1% THD limit. The amplifier is rated by the manufacturer to output 25Wx2 into 4-Ohms; 50Wx2 into 2-Ohms; 100Wx2 into 1-Ohm. @.03%THD @ 1KHz... Our Test was at 100Hz...

1. Do you think that we have determined the absolute, usable Power Scores, for each load, based on the measurements above?
a) Yes_____
b) No_____
c) Unclear_____

2. Do you think that we are able to develop a reasonable estimate of the true power potential of the amplifier, from the measurements depicted above?
a) Yes_____
b) No_____
c) Unclear_____

3. Do you think that these tests provide a reasonable estimate of peak-power into each load?
a) Yes_____
b) No_____
c) Unclear_____

4. Do you think that more investigation in required?
a) Yes_____
b) No_____
c) Unclear_____

Hint #1: Post

 

[Speedskater]

The bright green background is a challenge for my old eyes.
And I'm Irish.

 

[GaryProtein]

The bright green background is a challenge for my old eyes.
And I'm Irish.

I agree.

I tried to highlight the text to get more contrast, but the images are pictures, not text pages so I couldn't highlight.

 

[ack]

Great effort, but this is quite a bit unreadable.

 

[amirm]

I am working with Frank to get this uploaded as a pdf.

 

[F.Cook]

I am working with Frank to get this uploaded as a pdf.

Yes - just uploading a copy now - however, it will be highly compressed, but readable... I will remove the green back-ground...

Thank you Amim for your consideration.

Download the entire PDF from:

https://www.dropbox.com/home

Email: avforumdownloads@gmail.com
Password: aquafina

 

[F.Cook]

What is the 1% THD Power Limit?
Answer:

Is the 1% THD Power Limit based on Clipped Signals?
Answer:


What's the true RMS Power Limit of this amplifier, based on the graph above?
Answer:


How large is the disparity between true RMS, if you will, and the 1% THD depiction?
Answer:


Which one seems more accurate and therefore usable?
Answer:

 

[F.Cook]

Download the entire PDF from:

https://www.dropbox.com/home

Email: avforumdownloads@gmail.com
Password: aquafina

Green background removed!