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How to do a double blind test (DBT) that is not to be doubted (TBD)


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5 minutes ago, davewantsmoore said:

 

I don't understand what you're trying to do/achieve.

capture output at speaker terminals

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Short break for a proud dad moment, was watching my daughter compete in the All-State Jazz Competition in Melbourne. Man I wish I could have played in such an accomplished band at 15. There are 3 Jazz

Indeed.... but that isn't what MLXXX said.   He just said there wasn't any "hard" evidence presented.   It is irrational for anyone to believe that two signal are different from each other,

Strangely enough, I listen to music for the response in me.   The way that I check for "better" is: Am I enjoying the music more? Do I want to turn it up or put on more?  Am I

14 hours ago, MLXXX said:

That could indeed be advisable in some circumstances.

 

I think of it like airbags and seatbelts.

 

You are often going to be using inputs that have a lot more energy under the curve than music... and probably going towards maximum system gain (so ~105dB outputs).   Caution.

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2 minutes ago, davewantsmoore said:

 

In this situation it would be the current flow that would be of concern.... as the voltages would be low(er) when the impedance is low.

 

Of course the way to verify the amplifier is supplying sufficient current is to measure the voltage it is supplying. If the amplifier can maintain its voltage at its output terminals despite an unusually low impedance load, we know that it is copying, and is supplying the additional current the load is demanding.

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6 minutes ago, MLXXX said:

If the amplifier can maintain its voltage at its output terminals despite an unusually low impedance load, we know that it is copying, and is supplying the additional current the load is demanding.

How do you know that?

 

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18 minutes ago, davewantsmoore said:

How do you know that?

 

Because if it wasn't the voltage of the waveform would drop, e.g. creating a flattening of the peaks of the test sine wave.  Or the waveform would otherwise be pushed out of shape by strong reactive currents.

If the amplifier can maintain at its output terminals the integrity of the input waveform, we can infer it is coping with the abnormal load.

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2 hours ago, MLXXX said:

Because if it wasn't the voltage of the waveform would drop

 

It might.... but why is it impossible for the amplifier to maintain the correct voltage, and have the current "limited", or distorted, etc. ?!

 

 

There are the types of terrible assumptions that are made around "voltage drive" of speakers.

 

 

(Relevant to this discussion) we assume that if a voltage is made by the amplifier, that corresponding current will flow.     Perhaps true for a simple amplifier, and load.... but not necessarily.

 

(Relevant to other disucssions which have occurred from time to time around here)  we also assume that if a voltage is made by the amplifier.... that the corresponding current which flows, is actually representative of the music signal that we wish to drive the speaker with.

 

 

 

 

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38 minutes ago, davewantsmoore said:

It might.... but why is it impossible for the amplifier to maintain the correct voltage, and have the current "limited", or distorted, etc. ?!

 

If the speakers (including any associated passive crossovers) create such strong reactive currents within themselves that the speaker cones end up delivering distorted sound pressure waveforms even when fed perfect voltage waveforms by an amplifier, that surely is an issue to take up with the designers of the speakers!  We live in a world where, by convention,  audio power amplifiers are designed to deliver replicas of the input signal voltage waveform.

 

And so, all the designer of an amplifier for the general audiophile market can be expected to do is design it to deliver undistorted voltage waveforms  at very low output impedance.

 

On the other hand, if a speaker system manufacturer wants current feed for their specialist speaker system, that is an entirely different discussion!

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5 hours ago, MLXXX said:

the speaker cones end up delivering distorted sound pressure waveforms even when fed perfect voltage waveforms by an amplifier

 

Speakers don't move due to voltage.   The move due to current flow.

 

 

 

5 hours ago, MLXXX said:

We live in a world where, by convention,  audio power amplifiers are designed to deliver replicas of the input signal voltage waveform.

 

Forgetting about the speaker completely for a moment..... why is it not possible that while the amplifier is able to maintain the correct voltage..... that the current is not being clipped/limited by the amplifier?

 

You say that if the voltage is right that the current will be right?   Why?

 

 

5 hours ago, MLXXX said:

And so, all the designer of an amplifier for the general audiophile market can be expected to do is design it to deliver undistorted voltage waveforms  at very low output impedance.

 

?

 

5 hours ago, MLXXX said:

On the other hand, if a speaker system manufacturer wants current feed for their specialist speaker system, that is an entirely different discussion!

 

You seem extremely confused about how a speaker works.

 

All moving coil speakers are driven by current.   It is the current flowing through the voice coil that makes it move.    The voltage is not (directly) relevant.

 

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Dave, I will respond to your last post (about voltage drive), by PM.

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I find dave's inbox can't receive  the message I prepared for him, so I'll have to put it here, despite it taking the thread further off on a tangent!

 

________

 

 

Hi,

in the DBT thread you asked:

 

Forgetting about the speaker completely for a moment..... why is it not possible that while the amplifier is able to maintain the correct voltage..... that the current is not being clipped/limited by the amplifier?

 

You say that if the voltage is right that the current will be right?   Why?

 

Background

 

Audio power amplifier  theory 101 tells us that conventionally power amps are designed to deliver a faithful replica of the input signal voltage waveform at the output terminals.  That signal then passes through the speaker cable to the speaker cabinet where conventionally a passive crossover network will direct signals to 2 or more drivers.  Speaker system theory 101 informs us that a nominal speaker cabinet impedance of 8 ohms would in reality be different at different frequencies as a result of the interaction of a number of factors including voice coil resistance and inductance, crossover inductance, capacitance and resistance.  Also there is the complication of back EMF from speaker voice coils,  driver/cabinet resonance, and other factors.  In all a very complex load, that will typically vary well above and well below 8 ohms as seen at the speaker cabinet terminals.

 

How does the amplifier designer deal with the prospect of a variable complex load?  Answer: by designing for a very low output impedance figure. 

 

Consider a classic push pull Darlington pair solid state power amplifier configuration. The output power transistors operate in emitter follower mode and that of itself provides a low native output impedance to begin with. On top of there is substantial use of negative feedback.  The achieved output impedance is very low (as reflected in the high damping factor figures typical of this design of audio power amplifier).

 

Questions and answers

 

You ask, firstly:

Forgetting about the speaker completely for a moment..... why is it not possible that while the amplifier is able to maintain the correct voltage..... that the current is not being clipped/limited by the amplifier?

 

My answer:

Because if is not merely the mean voltage we are looking at but the precise shape of the waveform delivered by the amplifier. If the amplifier faltered (because of momentarily exhausting the power supply or momentarily reaching a current capability limit in the output semiconductors), there would be an identifiable disturbance to the shape of a test waveform. The classic disturbance is a clipping of the positive and negative peaks of a test sine wave. Other disturbances or anomalies are possible.  How would you test?  You could use a dual trace scope and overlay the input sine wave to the amp and the waveform at its output terminals, gradually increasing the test signal amplitude while looking for any anomalies to start to appear.  (Of course real life amplifiers are not perfect zero impedance sources and a very small differences inevitably will arise. However it must be remembered that the speaker cabinet crossover and drivers will introduce their own losses of much greater magnitude.  The amplifier source impedance, and hopefully the speaker lead impedance,  should be very small in comparison.)

 

You then ask:

You say that if the voltage is right that the current will be right?   Why?

 

My answer:

If an amplifier is able to maintain at its output terminals the shape and amplitude of a test sinewave across the full audible range when feeding a speaker system, i.e. no glitches or other disturbances in that waveform, that shows that the amplifier is coping with whatever current demands are being placed on it, whether resistive or reactive.  If it were not supplying enough current (either positive or negative), that would be revealed in the amplitude and shape (including maintaining phase alignment with the input signal) of the output terminal signal voltage.

 

On the aspect of whether the current is "right" for the speaker to perform well, that is a separate question beyond the responsibility of the amplifier designer. Conventionally all a power amplifier has to do is supply the signal voltage waveform faithfully.  If a speaker system behaves erratically when its terminals are fed a highly accurate signal voltage waveform at practically zero source impedance, the speaker system designer needs to go back to the drawing board! Or the designer needs to ask for a custom designed amplifier.

 

Cheers 

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Doing some more research lately on this topic, I am tending to answer this question to this topic, “How to do a double blind test (DBT) that is not to be doubted (TBD)”

For me I would say No I don’t think there is a way for us home hobbyists.

 

There is already something happening with DBT’s in Audio that for all intentional purposes pretty well makes everything sound the same or at least too hard to get results to show the contrary.

It may be all ok for Speakers and headphones with large differences, but once the differences are smaller, DBT’s do not seem to give meaningful results.

 

From looking lately at this with a bit of science help on the net, I have come across some interesting stuff and that science is progressing in these areas.

There seems to be some great many fields in science moving forward in the study of the brain.

 

 

This is a interesting watch

https://www.youtube.com/watch?v=HRE624795zU

 

 

One of the problems I think that is with dbt’s,  is that this is not the way we normally listen to music.

Cover up components, trying hard to listen to individual notes, instruments, vocals and playing small sections of the music over and over in the hope of trying to pick up a difference.

Once your in this mindset mode I think you do not listen to the music like in normal listening sessions.

Music listening I would think normally washes over you. You can get emotions, visuals, maybe it brings on past memory's etc as you listen.

I have read quite a few reviews now where a reviewer is reviewing a few products, then puts a new one in and before he notices, he is listening to whole tracks of music, lost in the music itself and forgot where they are at.

That would be hopefully what I’m looking for in my buying of products, the outcome is just getting lost in the music.

 

As you look at that video you notice a musician’s brain lights up different when listening to music or composing something. I would loved to have see how a brain lights up in a DBT test when someone is concentrating trying to pick a difference in a segment of music played over and over.

I would suspect it would be very different again. I doubt there would be much action happening in the pleasure zones of the brain. Just a guess on my part until someone does the tests.

 

When you look online at the professionals doing the DBT's Alan shaw come to mind plus a few others, they tend to say to leave your feelings/emotions at the door before doing these tests. It seems in science its hard to measure emotions/feelings etc.

You also tend to see they only get good consistent results to show a preference from components with big changes in sound like speakers and headphones.

I don't see Harman doing them on Dacs, amps, cd players etc as I would think it may be too hard to get any meaningful results compared to speakers plus it is not in their interest as there products are the main concern for them.

 

 

Also I do not think you can even record something and then expect you can use those recordings to compare. Especially when you also play them back on a dac.

Just have to look at Rob Watts work and presentations. He has extensive info on this, so don’t ask me to explain (way over my head), just watch some of his presentations.

Most recording devices and Dacs are not up to par. As someone in the past on here would of said, there broken. 🙂 

 

As you move up to more expensive Dacs, there filters can be a lot better as Rob Watts points out with his Dac.

You go with something like a topping Dac and they just use off the shelf filters.

Could be why I do not like my Holo Dac in Oversampling mode as it uses off the shelf filters too.

Only use it in NOS mode as thats when I really enjoy this Dac over my listening sessions.

 

Could be why I do not get the same enjoyment from other Dacs I have tried that are sigma delta types with off the shelf filters. Maybe if I tried some more upmarket ones this could change but happy with my choice of R2R Dac.

Could be tempted on the May Dac one day.

 

So summing up, I am not against DBT's but for me, they did not give me anything meaningful to improve my goal of enjoying my music more. I actually went backwards doing them.

I'm looking forward to the day we can put a lightweight headphone type device on our head to monitor our brain activities at home.

Not to prove anyone wrong or right, but possibly to get more info, so people may possibly select the right components to suit themselves better.

 

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1 hour ago, rocky500 said:

There is already something happening with DBT’s in Audio that for all intentional purposes pretty well makes everything sound the same or at least too hard to get results to show the contrary.

It may be all ok for Speakers and headphones with large differences, but once the differences are smaller, DBT’s do not seem to give meaningful results.

 

You also need to consider whether audio engineering may have improved to the point where differences are not audible at all with some equipment, be that for a listener concentrating hard for a DBT, or settling back at home immersing themselves in the music.

 

That really is a very straightforward explanation.  I suggest it should not be dismissed lightly!  

 

It would not be surprising an outcome when you consider that human ears can detect loudness changes down to about 0.25dB in very, very good conditions, and 24-bit ADCs and DACs routinely operate down to at least the 20th bit. By my calculations the 20th bit represents a change in  a PCM encoded signal of 1/(2^19) = 1/524288, or 0.0000166dB, compared with full scale amplitude. 

 

We don't seem to have trouble accepting that human beings can't read newspaper headlines at a distance of 1km using the eyesight Nature has provided; whereas a telescope makes that possible, or a digital camera with a zoom lens.

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18 minutes ago, MLXXX said:

 

You also need to consider whether audio engineering may have improved to the point where differences are not audible

 

I can only say for me, I have found this is not the case as when I do all the tests at home, in the end I get different enjoyment in my listening sessions with different products.

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Posted (edited)

Perhaps we are trying to blind test the wrong thing. 

 

 

The question I have for the neuroscientists out there, is do these sorts of  devices change anything as far as being influenced by bias or external stimuli? ie are your brainwaves a reflection of your bias?

 

It may be a good investment for the curious audiophile? I assume you could replicate the experiment posted previously about high frequency content?

 

https://www.diygenius.com/hacking-your-brain-waves/

 

https://choosemuse.com/muse-2/?store_id=au&utm_source=Google&utm_medium=PaidSearch&utm_campaign=Shopping&gclid=CjwKCAjwiLGGBhAqEiwAgq3q_nkzGuXnKXBdg9ARBk5KM3WhrMT3WlvQEoZI6AClubunrVdFIqJN5xoCexMQAvD_BwE

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On 18/06/2021 at 8:06 AM, frednork said:

capture output at speaker terminals

 

Great theory but again not possible for most people .  They would also need to know what amperage they should be looking for .  

 

If they need to measure at speaker terminals. they could  simply walk around to the front and listen to the sound.   

 

When looking for amplifiers with high amperage output the process can be streamlined a bit. Amplifiers that claim to double power output each time into 4, 2 and 1 ohms would be contenders  and if looking at Class A or Class A/B, the amplifiers would need  to have massive power supplies which would make them very heavy indeed.      To differentiate amongst these, measurements would be useful  and I personally take these into account before moving to audition.  

 

But when you do listen to amps of this calibre from Gryphon, Vitus, Accuphase. Pass labs and others they do each have a sonic signature as intended by their designers in order to appeal to their specific target audience.  They do measure differently but it is an entirely different matter to be able to predict exactly how each will sound from the specs.  If all specs are done according to the same standards ( a big "if" in the hifi world) then I think differences such as in SNR  and distortion can be differentiated if they are significant enough, but there are so many other aspects of the sound that simply cannot be predicted by specs and currently measured parameters alone. 

 

 

 

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3 minutes ago, TP1 said:

If they need to measure at speaker terminals. they could  simply walk around to the front and listen to the sound.  

 

yes, perhaps, but if that were enough for everyone then this thread and DBT testing would be totally unnecessary (some would say that is the case regardless)

 

5 minutes ago, TP1 said:

Great theory but again not possible for most people .  They would also need to know what amperage they should be looking for .

 

The fact it is not done much and it would be different from the output at line level or into a dummy load has some interest for me. Having looked beyond this thread for advice I have found there are some issues for amps that are balanced in their output (ie live on both -ve and +ve sides. Attaching a device along the lines of suggested above may be disastrous and blow your amp up so would suggest to anyone thinking about this to do your homework properly. As my Vitus is such an amp that circuit would be catastrophic and even with some extra protection I would be hesitant as to whether it is worth the risk.

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3 hours ago, aussievintage said:

 

it's current not amperage

 

And the measure of current is?  

 

120216786_ScreenShot2021-06-19at7_17_03pm.png.bce3b0e0cb0a98123150725c27f023cb.png

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20 minutes ago, aussievintage said:

Yep, but it's called current.

 

Yep -  but its measured in amps.  I was referring to the measurements  which was the topic of conversation.  People know what's being said and while you may  not like the way the discussion goes from time to time, being pedantic for the sake of it is not constructive. 

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9 hours ago, TP1 said:

 

Yep -  but its measured in amps.  I was referring to the measurements  which was the topic of conversation.  People know what's being said and while you may  not like the way the discussion goes from time to time, being pedantic for the sake of it is not constructive. 

 

Being correct is always worthwhile. :) 

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I've heard the informal term "amperage" used in relation to fuses; equivalent to the more general term "current rating". Years ago we'd see the word "Amperes" in technical magazines, but today we pretty much only see "Amps".  Some people still call the capacitors used in electronic circuits, condensers. And a handful  of people would still say kilocycles rather than kilohertz. Inches is still a very common usage in Australia for TV set diagonals.

 

 __________________

 

@frednork, I've been thinking of a blind test exercise involving different brands of microphones to record a piano; with two different ADCs for capturing the microphone signals.  I envisage that telling the mics apart will be easy, and telling the ADCs apart will be hard!  It may take me a couple of weeks before I have the recordings ready.

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On 18/06/2021 at 10:30 PM, MLXXX said:

You ask, firstly:

Forgetting about the speaker completely for a moment..... why is it not possible that while the amplifier is able to maintain the correct voltage..... that the current is not being clipped/limited by the amplifier?

 

My answer:

Because if is not merely the mean voltage we are looking at but the precise shape of the waveform delivered by the amplifier. If the amplifier faltered (because of momentarily exhausting the power supply or momentarily reaching a current capability limit in the output semiconductors), there would be an identifiable disturbance to the shape of a test waveform.  The classic disturbance is a clipping of the positive and negative peaks of a test sine wave. Other disturbances or anomalies are possible.

 

You didn't answer why.

 

You've just restated your claim that if the amplifier hit its current "limit" somehow.... that you would see this by looking for clipping in the voltage.

 

 

On 18/06/2021 at 10:30 PM, MLXXX said:

You then ask:

You say that if the voltage is right that the current will be right?   Why?

 

My answer:

If an amplifier is able to maintain at its output terminals the shape and amplitude of a test sinewave across the full audible range when feeding a speaker system, i.e. no glitches or other disturbances in that waveform, that shows that the amplifier is coping with whatever current demands are being placed on it

 

Why does it show that?

 

Why cannot the VAS hold the the voltage to be whatever it is supposed to be moment to moment ... but the incorrect amount of current flowing  (for example, due to gross current limiting/clipping.... or any other issue/error)

 

 

On 18/06/2021 at 10:30 PM, MLXXX said:

If it were not supplying enough current (either positive or negative), that would be revealed in the amplitude and shape (including maintaining phase alignment with the input signal) of the output terminal signal voltage.

 

Why?

 

What is "enough" current, in the example of a "voltage source" amplifier?    The input signal causes the amplifier to create a voltage at it's output.....   so what is "not enough" current?

 

Yes, it's true that if the amplifier was clipping/limiting the current output .... that the VAS may also be distorting the voltage.... but why do you say that is "always true"?

 

On 18/06/2021 at 10:30 PM, MLXXX said:

On the aspect of whether the current is "right" for the speaker to perform well

 

That isn't what I was asking (sorry, if confusing).

 

 

What I am trying to get at with all of this, is that the idea that "all you need to do is look at the output voltage to know that the current is perfect" is not true, at least not all the time.

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49 minutes ago, MLXXX said:

I've heard the informal term "amperage" used in relation to fuses; equivalent to the more general term "current rating". Years ago we'd see the word "Amperes" in technical magazines, but today we pretty much only see "Amps".  Some people still call the capacitors used in electronic circuits, condensers. And a handful  of people would still say kilocycles rather than kilohertz. Inches is still a very common usage in Australia for TV set diagonals.

 

I think there is no  need to correct peoples grammar, spelling or terminology as long as you understand what they are saying. There are people that come from all over the world on this site and the value of their contributions are not measured by how correct their English/teminology is. The appropriate thing to do if it unclear is to ask for clarification.  Anything else is annoying for  them (for me also and I suspect a great many others) and reflects poorly on the person being "pedantic".

 

49 minutes ago, MLXXX said:

 

@frednork, I've been thinking of a blind test exercise involving different brands of microphones to record a piano; with two different ADCs for capturing the microphone signals.  I envisage that telling the mics apart will be easy, and telling the ADCs apart will be hard!  It may take me a couple of weeks before I have the recordings ready.

 

Yep sure, the microphone part should be a doddle. I used to have a microtech gefell program which did that with all the classic microphones. Sadly cant find it anymore. It was pretty obvious if you spent a decent time with those microphones exactly what they were so that part should be no problem. The ADC one is limited by the ADC's you choose to compare and of course the dac used to listen to them. As I said before unless you can show that someone can detect a difference reliably, then you are at risk of a null result. But hopefully someone can detect a difference reliably. Good luck!! I will certainly have a go.

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5 hours ago, davewantsmoore said:

What I am trying to get at with all of this, is that the idea that "all you need to do is look at the output voltage to know that the current is perfect" is not true, at least not all the time.

Perhaps this analogy will help.

 

If the power authority monitors the voltage at the street power pole* to which the mains switchboard of a house connects, and the voltage remains constant in amplitude (230.00V) , constant in frequency (50.000Hz), constant in phase (0.000 degrees offset ), and with very low harmonic distortion, the power authority can be satisfied it is meeting its obligations to supply mains power current to that house.

 

_____________

 

* Assume the cable from the house to the power pole connects to only one of the three phases at the power pole. Assume the voltage is measured between that phase and the neutral cable on the power pole.

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5 hours ago, frednork said:

I think there is no  need to correct peoples grammar, spelling or terminology as long as you understand what they are saying.

 

As an engineer and scientist I find this incredible.  How can you be discussing doing DBT testing and not care to even use the correct scientific terminology for what you are testing?  It makes a joke of any efforts to "not be doubted".

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1 minute ago, aussievintage said:

 

As an engineer and scientist I find this incredible.  How can you be discussing doing DBT testing and not care to even use the correct scientific terminology for what you are testing?  It makes a joke of any efforts to "not be doubted".

 

I have stated my opinion, I will let others decide what is important to be pedantic about and what is not.

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49 minutes ago, aussievintage said:

 

As an engineer and scientist I find this incredible.  How can you be discussing doing DBT testing and not care to even use the correct scientific terminology for what you are testing?  It makes a joke of any efforts to "not be doubted".

I didn't know this.

 

What area of science do you have a PhD in?

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22 minutes ago, muon* said:

I didn't know this.

 

What area of science do you have a PhD in?

 

 

LOL.  It's bad enough even admitting I am from that side of things  (although I suspect many realise it from my posts) without trotting out qualifications.    But note,  I put "engineer" first.  I only have the usual Bachelor Degree, so maybe there's some hope for me.    PM sent if you wish further discussion.

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Ah...

Thanks.

 

Edit: somewhat, reassuring as anyone can be a scientist by the definition as there is no formal process to determine who is a scientist and who is not.

According to wiki anyhoo :)

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1 hour ago, aussievintage said:

 

 How can you be discussing doing DBT testing and not care to even use the correct scientific terminology for what you are testing?  It makes a joke of any efforts to "not be doubted".

 

Wrong. You are miles off the mark.    It is a question of context and gramma and it is not up to you to  decide in any event . I used   the term "current" more than once before in this thread but then the discussion turned to electrical measurements and the only thing mentioned was voltages. "Voltage"  like "Amperage" is a noun  and they are both measurements of different  underlying electrical attributes .  If it is OK to use "Voltage" in a sentence in the context of this discussion, then the term "amperage"  is appropriate when referring to nouns describing electrical measurement.   

 

And please don't pretend to be an expert on this - you entirely  ignored or don't know about  the the relevance of current,  and your only contribution was to  say "measure voltages".   You are wrong about this being all there is to it, and being pedantic about how someone expresses the measurement of current  does not make you right.

 

 

On 17/06/2021 at 7:23 PM, aussievintage said:

 

 

Just measure the voltage at the speaker terminals, and use a simple voltage divider to get line level volts.    You can calculate what to expect from the power output of the amp and the speaker impedance.

 

 

 

 

 

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6 minutes ago, TP1 said:

And please don't pretend to be an expert on this - you entirely  ignored or don't know about  the the relevance of current,  and your only contribution was to  say "measure voltages".  

 

Talk about out of context!  That was a response to a request for information on how to connect a line level device to speaker terminals.  Nothing more.

 

Wow !!!  Starting to understand why people pack up and leave this place,   sheesh

Edited by aussievintage
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For the record I'm fine with amperage as it defines a measure of current.

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Amperage is probably the least recognised and most important value of any given amplifier.

 

It equates to torque in a car engine being far more important than power (in KW ). Both amperage and torque are really what makes amplifiers and engines do their best work. ( As opposed to KW and WPC )

 

I am no engineer, but this is how I used to explain to customers when they were purchasing a suitable amplifier for an existing hi fi system or as an upgrade and most people found this to be a helpful analogy.

 

I realise this has nothing to do with DBTs but I wanted to post it anyway and all the engineers here may need to cut me some slack for what I have posted.

Thank you in advance.😇

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7 hours ago, frednork said:

I think there is no  need to correct peoples grammar, spelling or terminology as long as you understand what they are saying. There are people that come from all over the world on this site and the value of their contributions are not measured by how correct their English/teminology is. The appropriate thing to do if it unclear is to ask for clarification.

Well said!

 

 

The term "amperage" is not in mainstream usage in electronics publications today, but it still appears in dictionaries and it isn't at all hard to guess what is meant when the term is first encountered.  

 

Interestingly, the way we use the word "voltage" today is a broader usage than in former times.  Publications of 100 years ago would often refer to EMF, or electromotive force, rather than to voltage. The volt is a measure of EMF (or of "potential difference") just as the amp (or ampere) is a measure of current.

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1 hour ago, rantan said:

Amperage is probably the least recognised and most important value of any given amplifier.

 

I believe this is a broad reference to the capacity of an audio power amplifier to maintain its delivery of an undistorted waveform at frequencies where the connected speaker system's impedance becomes unusually low, and/or highly reactive.   (To achieve that, the amplifier needs to have a capacity to source or sink a large current flow.)

 

I note that unlike "maximum engine torque" which can be measured and listed in the specifications of an engine, amplifier "amperage" is a broad, descriptive term, lacking a standard measuring method. 

 

Suffice it to say that if conducting a DBT one would want to ensure that any power amplifier used to present the test sounds to test subjects would have an ample reserve of "amperage".

Edited by MLXXX
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1 hour ago, rantan said:

Amperage is probably the least recognised and most important value of any given amplifier.

 

It equates to torque in a car engine being far more important than power (in KW ). Both amperage and torque are really what makes amplifiers and engines do their best work. ( As opposed to KW and WPC )

 

I am no engineer, but this is how I used to explain to customers when they were purchasing a suitable amplifier for an existing hi fi system or as an upgrade and most people found this to be a helpful analogy.

 

Before the thread was derailed, I previously mentioned  that  traditional  specs don't tell the full story in a couple of posts

 

On 15/06/2021 at 1:11 PM, TP1 said:

Some speakers have  impedance curves that would be very challenging for  many amplifiers - even if  the specs should suggest  there will be no problem.

I  recall an experiment with speakers that turned out to  being particularly demanding.  The specs said sensitivity  of 90db and impedance of 4 ohms.    On test the impedance was measured to vary between 3 and 15 ohms in the first 100hz alone.   As it turned out, only a substantial amplifier with high current  capacity was able to drive the speakers  properly.  

 

Watts per channel and impedance are not enough to predict how amplifiers will sound or how well they will drive speakers. Very few amps specify current output  although some guidance can be gained from how well amplifiers  perform into lower impedances if the specs are known. 

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3 minutes ago, MLXXX said:

Suffice it to say that if conducting a DBT one would want to ensure that any power amplifier used to present the test sounds to test subjects would have an ample reserve of "amperage".

 

They would need to be the same . 

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On 20/06/2021 at 7:22 PM, TP1 said:

 

They would need to be the same . 

I was not envisaging using a number of different model amplifiers to present the test sounds.

 

I was envisaging comparing different sounds fed into a single sound reinforcement system.

My comment was that whatever amplifier was used to present the test sounds, it should have plenty of "amperage"* to do the job. 

 

______

 

* That is, current capability.

Edited by MLXXX
clarity
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