ABox response and potential fault

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ABox response and potential fault

Post by Experimental »

Hi,

I recently purchased the ABox and I'm really not certain that it's functioning correctly, and I was hoping someone else with the device could confirm the behaviour. In the first file that I have (hopefully) attached is a very simple waveform: It's a 440 hz sine wave that starts at 100% amplitude, steadily decreases to 20% (at the 10 second mark), then reverses and increases back to 100%.

On my ABox, the output from this file is absolutely nothing like you would expect. I set my audio device output to 100% (and have tested at slightly lower volumes, to avoid any potential clipping related issues), and I set the ABox to a reasonable output level (around 50%), and play the file.. the output actually increases from the 3 second to 5 second mark, then it completely drops off a cliff at 6 seconds and there is zero output. The output comes back quite suddenly and strongly at around 11/12 seconds, and stays at roughly the same level until the file ends (and loops). The audio level LEDs react correctly for the file.

This surely cannot be the expected output for such a simple file? Similarly, using a tool such as the one here: https://onlinetonegenerator.com/ - I set the volume slider on the site to 100% and play a test tone, and turn the ABox up to to a comfortable, high level. When I take the volume slider down on the site, the power output from the ABox increases until I get to about the 80% mark, then very suddenly drops to 0, at around 75% on the slider.

The second attachment (test_mono.mp3) is another file that results in a highly unexpected output. It's taken from a very long stim file that somebody has designed for a two channel device, that I have converted to mono to see if it explained what I experience with it (it did not).

The file produces some quite pleasurable sensations with the ABox set to around 60%. If you view the file (or listen to it) you can see that beginning at around 41 seconds is a gradual fade out to silence. At around 43 seconds, my ABox produces what I can only describe as horrifically shocking and painful 'thumps', resonating at around 2 hz, at a much higher power output than anything previously produced by the file. Again, there is nothing in the waveform that indicates that this should occur, and it seems highly likely that it's linked to the "spike / peak on 50%" thread that somebody posted a few years ago.

WARNING: If you're testing this file with an ABox, keep your hand directly on the power dial! I don't think that I'm exaggerating to say that the sensation at 43 seconds is extremely painful, if your device reacts in the same way as mine :)

Thank you for reading, and I very much hope that somebody with an ABox can confirm that this behaviour is not normal!
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Re: ABox response and potential fault

Post by admin »

The ABox, like the 2B was created to react to standard sound files - music. Why? because we like to listen to what we feel, and single tones are so boring to listen to during a long play session.

The reaction is complex as the ABox is not just an amplifier. nor does it have the level of signal processing in the 2B. It is not designed to react to a single audio waveform at a single frequency as an amplifier or stereo stim device would, it is designed to use more complex audio such as voice and music and is also highly reliant on the feeling of the subject.

It sounds like you are expecting it to react as a classic amp based stim device, whichj it is not, and possibly over thinking the process. The fact you are worrying about clipping etc give some indication to this.

The ABox is not not just an amplifier, nor is it an ET312 and using material 'designed' for other devices, is not going to give you the same results, or at least its not going to give you results you might expect. Single tones are actually quite boring, and humans react better to a wide range of frequencies employed at the same time - think a flute v the whole orchestra - which sounds more interesting?, which has more range? Just because everyone uses single tones does not mean that it is right for the ABox.

Your question is similar to playing Gun's and Roses and asking why your neighbour hates the music....its down to personal choice, and you idea of what 'it' should do is different to others.

If the ABox is responding to sound, then the ABox is generally working (failure modes in the ABox tend to boil down to it simply no output). If you feel this then pin the support team, but if its down to 'it doesn't 'work' with this file' then that is not going to be seen as a fault, but more perception.

The solution? put the signal generator away, plug some music you enjoy, in wire yourself up and sit back and enjoy.... and experiment for your own needs now, not everyone else's idea as to what 'should' work.

Si
E-Stim Systems Ltd
Experimental

Re: ABox response and potential fault

Post by Experimental »

Hi Si, thank you for the lengthy response. I agree that single tones are boring, my intention in using them was to get a rough idea of how the ABox reacts with a consistent, repeatable input before I provided it with something more complex.

I emailed your customer services before I made the purchase asking how the output signal is 'mapped' from the input, and was told by Mick that there was no mapping. I stated that my intention was to create an application in order to control the ABox, but with what you've said here, it seems that might be impossible (at least in any meaningful, predictable manner). It would have been nice to have had that information earlier.

You're right in that I was expecting the ABox to behave like a stereostim device, and the information page for the ABox reinforced that belief. I had considered building my own stereostim, but buying a product designed for the purpose from an established company seemed like a better, safer option, despite the expense.

The product page for the ABox says "Select your favourite Stim track, plug in and lie back", so I thought that 'designed' stim tracks would at least be compatible. The files offered here https://e-stim.info/downloads/audio are exactly that, not music, which again reinforced my belief that the ABox would react appropriately, but it does not. The product page also states that the output is "similar, both in amplitude and frequency [to the audio input]", but this is not true whatsoever - the amplitude of the audio signal is effectively meaningless.

My complaint is not that "the ABox doesn't work with this file", it's that the information in the preceding paragraph, taken from the product page, is completely inaccurate.

Maybe one of the more experienced users can chime in, but my expectation is that an audio file that produces particular sensations would produce extremely similar sensations at a lower intensity, if the audio volume was lowered. Instead the ABox produces an unrecognisable, unpredictable output. I don't think that is a matter of personal choice or that my expectation is 'different to others'. I would be quite frankly shocked if anybody agrees that my expectation is unusual or unreasonable.

I appreciate that you believe that using music as an input is the way that the ABox should be utilised, but if a simple fade out (as in test_mono.mp3 in my previous post) results in a spiking painful output, I'm not going to risk using the ABox with music that has a high variation and dynamic range. Receiving a few random full power pulses as a piece of music that I know well is fading to zero doesn't really sound like my idea of fun, and is absolutely not what I bought the ABox to experience.

Your audio file download page even mentions using Audacity to generate specialised tones to drive the unit and that they work "very well", to find out after purchase that I should not be doing so is a little jarring.

I hope that you can try test_mono.mp3 with an ABox hooked up to an oscilloscope and see if the spikes at 43 seconds occur. I have a feeling from your response (and the previous "50% spike" thread by "Singular", where "Yogi" had the same issue) that if they do, then this behaviour will be considered 'normal'. If so, please post an image of the oscilloscope output so that other potential buyers can make an informed decision on whether or not that is something that they would want, before purchasing the device. If the spikes do not occur, then my ABox must be as faulty as it feels, and I will have to take advantage of the lifetime guarantee and get it repaired/replaced.

Thank you for reading.
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Re: ABox response and potential fault

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Experimental wrote: Sun Aug 02, 2020 4:40 pm Hi Si, thank you for the lengthy response. I agree that single tones are boring, my intention in using them was to get a rough idea of how the ABox reacts with a consistent, repeatable input before I provided it with something more complex.

I emailed your customer services before I made the purchase asking how the output signal is 'mapped' from the input, and was told by Mick that there was no mapping. I stated that my intention was to create an application in order to control the ABox, but with what you've said here, it seems that might be impossible (at least in any meaningful, predictable manner). It would have been nice to have had that information earlier.
You asked about about a number of aspects, from processing to mapping the input to output. The ABox doesn't have any 'mapping' as such as that infers that there is a signal processing relationship to the input and the output. You asked does the ABox 'learn' aspect of the output, again the answer was it does not. You also asked if there would be a difference between a sine wave and a square wave of the same frequency, and the answer given was there should be. The problem with answering a range of questions such as these is there appears to be a number of assumptions. The ABox does not have a signal processor on board, so learning/mapping and such link are all processes that we would associuate with DSP techniques, indeed the 2B does have DSP software on board. The ABox is prediuctable in so much that what it does with a signal today will be the same as what it does with the same signal tomorrow, but systems are highly dependent on aspects out of our control - the subject, electro placement intensities etc etc. In addition the signal produced to generate the sensation is not a sinewave, as a sinewave is highly inefficient in transferring energy and thus sensation.

So the simple answer is we gave you correct information, but given the wiide range of E-Stim sensations possible its impossible for us to cover every eventuality[/quote]
You're right in that I was expecting the ABox to behave like a stereostim device, and the information page for the ABox reinforced that belief. I had considered building my own stereostim, but buying a product designed for the purpose from an established company seemed like a better, safer option, despite the expense.
The questions you asked would not have applied to a classic stereostim device, so it was not clear that was what you where looking for. You didn't ask is this a stereostim box, to which the answer would have been no, but that is not your fault, or ours, we just tried to answer the questions you asked to the best of our ability.
The product page for the ABox says "Select your favourite Stim track, plug in and lie back", so I thought that 'designed' stim tracks would at least be compatible. The files offered here https://e-stim.info/downloads/audio are exactly that, not music, which again reinforced my belief that the ABox would react appropriately, but it does not. The product page also states that the output is "similar, both in amplitude and frequency [to the audio input]", but this is not true whatsoever - the amplitude of the audio signal is effectively meaningless.
The Amplitude of the audio signal does offer control over the output, that is fundamentally how the ABox works, otherwise all you would feel is a steady output even with no input. Getting the sweet spot where the input is driving the output how you wish is harder, and is very dependent on what levels are set - ie both the input level and the output level - and remember the leds only give an indication of input. Its one of the reasaons we suggest people experiment.

It works with my 'favourite tracks', that does not mean that it will work with all - its a figure of speech. Just because you like a track does not mean that I would, therefor the point is what? Most of the downloaded tracks are not actually single tones either - some are some aren't so that would indicate there is a relationship between the input and output. As to the input and output the answer is yea and no. The output on a scope will not match, the feel will - well in terms of sensation anyway. So higher frequencies will feel different to lower frequencies, higher amplitudes will feel different to lower, but the human body response to frequencies is different to that of the human ear so there is no exact correlation as you might be assuming.
My complaint is not that "the ABox doesn't work with this file", it's that the information in the preceding paragraph, taken from the product page, is completely inaccurate.
There is no detail in the page - its opinion based on our experiences, and that of our customers over time - the ABox has been around since 2006, with many happy users. Put simply the ABox converts sound into sensation, how to qualify the exact effects of that process is impossible when you connect a human up to it. Humans are not pieces of test gear - we vary. What was written is perfectly correct with the undersatanding that every product description in exisitance is based on opinion - otherwise all our cars, based on recent TV adverts) would be setting forests on fire and saving furry animals.
Maybe one of the more experienced users can chime in, but my expectation is that an audio file that produces particular sensations would produce extremely similar sensations at a lower intensity, if the audio volume was lowered. Instead the ABox produces an unrecognisable, unpredictable output. I don't think that is a matter of personal choice or that my expectation is 'different to others'. I would be quite frankly shocked if anybody agrees that my expectation is unusual or unreasonable.
I am an experienced user, I as the first ABox user mainly as I designed it!!. Since intensity is one of the key elements of stimming, it's hard to see how a lower intensity v a higher intensity is not going to give a different sensation. We are not a linear amp, we are complex. As to the output being unrecognisable -I disagree you are comparing two complete different items sound and sensation. I know people who can identify music from the feel of the ABox stimed version, so clearly its not unrecognisable.
I appreciate that you believe that using music as an input is the way that the ABox should be utilised, but if a simple fade out (as in test_mono.mp3 in my previous post) results in a spiking painful output, I'm not going to risk using the ABox with music that has a high variation and dynamic range. Receiving a few random full power pulses as a piece of music that I know well is fading to zero doesn't really sound like my idea of fun, and is absolutely not what I bought the ABox to experience.
The ABox is designed to work with music. The fact it works with some Stim tracks is a bonus, but music is what the ABox was created to work with.

You could always ask support to have a look at the unit, but generally unexpected spikes with audio sources have many causes and are dependent on many factors - electrodes, wires, the subject, the levels being used, the device used to generate the audio, the connections between - all can be a factor.
Your audio file download page even mentions using Audacity to generate specialised tones to drive the unit and that they work "very well", to find out after purchase that I should not be doing so is a little jarring.


Audactity is an option yes, as are many others. Some of the Demo tracks where produced on a KORG synth. but again not every tone or track is going to work for you.
I hope that you can try test_mono.mp3 with an ABox hooked up to an oscilloscope and see if the spikes at 43 seconds occur. I have a feeling from your response (and the previous "50% spike" thread by "Singular", where "Yogi" had the same issue) that if they do, then this behaviour will be considered 'normal'. If so, please post an image of the oscilloscope output so that other potential buyers can make an informed decision on whether or not that is something that they would want, before purchasing the device. If the spikes do not occur, then my ABox must be as faulty as it feels, and I will have to take advantage of the lifetime guarantee and get it repaired/replaced.
You what us to provide you with an oscilloscope trace? really? why? so we can all argue around what is and isn't correct. That is not how we work as a company. As I had said several times before humans are not test instruments, so any trace for 99.99% of people is complete meaningless, confusing and just results in pointless technical discussion which confuses even more people. The ABox has been around since 2006 and has quite a few happy users, so two posts on spiking when there are so many possible causes is not indicative of a defective design. Could it be faulty? possibly. But it is difficult to say without investigation of your unit.

Going back to you last question, the fact the spikes occur at 43 seconds with that specific file would indicate that its the file, not the ABox.... or do all files spike at 43 seconds? Have you tried different locations, levels etc etc? does it always spike at 43 seconds? if you half the file length do the spikes occur at 21ish seconds?

If you feel that you box is spiking them mention it to support and it will be investigated, We are always happy to look into issues, all you need to do it drop support an email and arrange to return the unit.


Si
E-Stim Systems Ltd
Experimental

Re: ABox response and potential fault

Post by Experimental »

Thank you again for another lengthy response.
The Amplitude of the audio signal does offer control over the output, that is fundamentally how the ABox works, otherwise all you would feel is a steady output even with no input.
A device that outputs a voltage when it detects an audio level over a certain threshold and turns it off when the audio is below that threshold passes that low bar of "driven by audio" as well, would you consider that an accurate descriptor for such a simple device? I certainly would not.

There is no detail in the page - its opinion based on our experiences
"similar, both in amplitude and frequency" is the detail that I refer to.

it's hard to see how a lower intensity v a higher intensity is not going to give a different sensation. We are not a linear amp, we are complex.
Providing the ABox with a constant 440 hz audio sine wave results in a particular sensation. Turning the "output level" dial to the right causes that sensation to become more intense. Turning it to the left causes it to become less intense. "More or less intense" is of course subjective, but not a single one of your users would disagree with that short definition of it, nor how the "output level" dial affects it.

My point is that I would have expected changing the amplitude of the 440 hz input sine wave to change the output in a similar fashion to that of the "output level" dial, nothing more. The ABox does not do that. Or maybe it does, and mine is faulty, which is what I am trying to determine.

You what us to provide you with an oscilloscope trace? really? why? so we can all argue around what is and isn't correct.
If a reduce input amplitude results in an increased output amplitude, that would be considered unusual and objectively 'incorrect', or not?

The ABox has been around since 2006 and has quite a few happy users
Maybe one of those happy users can attest to the predictability of the output based on a file that has never been provided to the ABox previously, but has been listened to or looked at with audio manipulation software. The same file will produce the same output repeatedly, I am not arguing that. I am saying that the output produced by the tiny sound file that I provided is unexpected by anyone's measure. As I said earlier, I think it may be related to whatever causes the "50% spike" issue that other users have mentioned. The user that sent the unit to you was told to provide an audio file for further testing, I have attempted to save time by providing the file in advance.

Going back to you last question, the fact the spikes occur at 43 seconds with that specific file would indicate that its the file, not the ABox.... or do all files spike at 43 seconds? Have you tried different locations, levels etc etc? does it always spike at 43 seconds? if you half the file length do the spikes occur at 21ish seconds?
I doubt this is a serious question but I will respond as if you're being sincere. The file that I provided causes these unusual spikes at the 43 second mark. Obviously not all files do the same thing. The spikes do not occur audibly when listening to the file, they do not appear in the waveform when analysed using audio software, they are produced solely by the ABox. I have given very specific information regarding "43 seconds" for your own testing purposes on another ABox, so you can either confirm that is it expected behaviour or confirm that my ABox is not behaving as it should.

I am certain that with a little effort I could determine precisely what it is about the signal that is causing my ABox to spike in the manner that I describe and produce any number of files that would cause the same thing, but if all ABox models react in the same way, what would be the point of me doing so? That would be a hardware issue that I am not qualified to comment on.

I have posted here to confirm whether or not it is likely that all ABoxes respond to that audio in the same manner. If it is not, then my ABox is faulty. If it is likely that they will all randomly peak when given an input such as that file, then I would like to return the ABox, since that very much goes against "similar to the output in amplitude".
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Re: ABox response and potential fault

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Experimental wrote: Sun Aug 02, 2020 7:24 pm Thank you again for another lengthy response.
The Amplitude of the audio signal does offer control over the output, that is fundamentally how the ABox works, otherwise all you would feel is a steady output even with no input.
A device that outputs a voltage when it detects an audio level over a certain threshold and turns it off when the audio is below that threshold passes that low bar of "driven by audio" as well, would you consider that an accurate descriptor for such a simple device? I certainly would not.

There is no detail in the page - its opinion based on our experiences
"similar, both in amplitude and frequency" is the detail that I refer to.
And as I explained in my previous answer that statement is correct in terms of human sensation. Higher frequencies will feel more intense and sharper than a lower frequency. Higher amplitudes will generally feel more powerful than lower amplitudes, both depending on what input you are using. The descriptor was in relation to human sensation as that is what the ABox is designed to do. It is not a piece of test equipment. It is a device created to provide sensation from sound, not designed to convert xHz into yHz at Z mA.
Providing the ABox with a constant 440 hz audio sine wave results in a particular sensation. Turning the "output level" dial to the right causes that sensation to become more intense. Turning it to the left causes it to become less intense. "More or less intense" is of course subjective, but not a single one of your users would disagree with that short definition of it, nor how the "output level" dial affects it.
Nor would we. Thats exactly what we would expect to occur.
My point is that I would have expected changing the amplitude of the 440 hz input sine wave to change the output in a similar fashion to that of the "output level" dial, nothing more. The ABox does not do that. Or maybe it does, and mine is faulty, which is what I am trying to determine.
So you are saying that you apply the signal and you get an output, then you reduce the signal and the output does not change? what happens if you drop the input to zero - does the out change then (and unplugging it may generate spikes). What amplitude are you actually driving at? how do you know its running at the level you think? what source are you using? Windows/Mac/MP3 player.
You want us to provide you with an oscilloscope trace? really? why? so we can all argue around what is and isn't correct.
If a reduce input amplitude results in an increased output amplitude, that would be considered unusual and objectively 'incorrect', or not?

Yes it generally would,there are caveats to this but not in the form of spikes as you are mentioning.
Going back to you last question, the fact the spikes occur at 43 seconds with that specific file would indicate that its the file, not the ABox.... or do all files spike at 43 seconds? Have you tried different locations, levels etc etc? does it always spike at 43 seconds? if you half the file length do the spikes occur at 21ish seconds?
I doubt this is a serious question but I will respond as if you're being sincere.
Why do you doubt this was a serious question? If you are doubting our sincerity at this stage, then I suggest we stop now as any further discourse is pointless.I was being sincere and trying to narrow down the possible issues. If the file causes an issue at a specific time, every time, and adjusting the file means the issue moves, then that indicates the issue is specific to that area of that file. If it occurs on any file at 43 seconds then that could be an indication of the ABox being the faulty item.
I am certain that with a little effort I could determine precisely what it is about the signal that is causing my ABox to spike in the manner that I describe and produce any number of files that would cause the same thing, but if all ABox models react in the same way, what would be the point of me doing so? That would be a hardware issue that I am not qualified to comment on.
But you are commenting on it. It would be a useful experiment, as we have not seen ABoxes being returned with specific issues around spiking. Generally the ABox is a reliable and robust design.
I have posted here to confirm whether or not it is likely that all ABoxes respond to that audio in the same manner. If it is not, then my ABox is faulty. If it is likely that they will all randomly peak when given an input such as that file, then I would like to return the ABox, since that very much goes against "similar to the output in amplitude".
Generally the ABox will respond to what you give it. It does not have the capacity to generate its own signals (not withstanding faults and electronic noise). .so no signal then no output.

I suggest contacting support and having your checked would be a good start.

Si
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Re: ABox response and potential fault

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I have also plugged in your fade out wav file in to my Fairlight DaVinci Resolve editing desk, which is the only thing I have at home with a FFT, and you have a distinctive dull click at the crossover point - I can hear it as well as see it on the FFT display. I can also hear it on my PC when just playing the wav file...... This sort of thing will be picked up by the ABox to generate a spike you mention.

Si
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Experimental

Re: ABox response and potential fault

Post by Experimental »

"similar, both in amplitude and frequency" is the detail that I refer to.
And as I explained in my previous answer that statement is correct in terms of human sensation.
I'm sorry but that doesn't really make much sense to me when the rest of the quote is taken into account:

"With the ABox, the sound signal itself drives the output signal, so the output is similar, both in amplitude (loudness) and frequency (tone) to the input signal"

So you are saying that you apply the signal and you get an output, then you reduce the signal and the output does not change?
As my first post indicated, using the test tone generator, the output increases when the input amplitude decreases, until a point (at around 75%) where it drops to zero. I gave clear instructions on how to reproduce this. But it's a minor point in comparison to what happens with the "test_mono.mp3" attachment.

What amplitude are you actually driving at?
An amplitude that causes the "100% red light" to flash, as in the instruction booklet indicates to do. Also tested at a lower amplitude.

what happens if you drop the input to zero
The output drops to zero. As it does at much higher input amplitude than zero, as outlined previously.
If the file causes an issue at a specific time, every time, and adjusting the file means the issue moves, then that indicates the issue is specific to that area of that file.
Correct, the issue is specific to that area of the file, which is why I have provided to you for your own testing and analysis. Nobody has downloaded that file yet, if you do, you will understand why I am confused as to how spikes in the output could exist from it.
That would be a hardware issue that I am not qualified to comment on.
But you are commenting on it.
I am not commenting on what is going on with the hardware to cause the issue that I am questioning. I have provided a file and instructions for you to reproduce it with another device, if it is possible to do so.

I am just trying to understand why a product I would very much like to use and enjoy is behaving in a manner that does not really make much logical sense.

It would be a useful experiment, as we have not seen ABoxes being returned with specific issues around spiking.
Is the file that I have already provided (test_mono.mp3) not useful for that purpose? If you are unable to reproduce what I am describing with that file then it will confirm that my ABox is faulty and I will happy to return it for you to determine why that is. If you do reproduce it but find a fault with the audio that can be blamed, then I will experiment and see if I can produce a less complex file that exhibits the same behaviour. Since I do not own an oscilloscope my only method of testing would be on my own body, and as I have described, the painful sensations that file creates are not something I'm keen to intentionally seek out.

I have also plugged in your fade out wav file in to my Fairlight DaVinci Resolve editing desk, which is the only thing I have at home with a FFT, and you have a distinctive dull click at the crossover point
Thank you for looking at that file. I am aware of the point in the middle of that file, but that does not produce a spike in output. That file was to demonstrate the other issue that I mentioned in my first post:
the output actually increases from the 3 second to 5 second mark, then it completely drops off a cliff at 6 seconds and there is zero output [until around 11 seconds]
The peaky 'thump' sensations are in test_mono.mp3, at the 43 second mark. When the audio amplitude is steadily decreasing.
Experimental

Re: ABox response and potential fault

Post by Experimental »

Hi Si,

I have done some further testing and can give some extensive information so that you, as the designer, can say whether or not my ABox is functioning as intended. You said that failures for the ABox are usually of the "no output" variety - that is not the issue that I have, so if I return it for testing I presume that your team will come to you to determine whether or not it is faulty. They will be able to reproduce exactly what I am about to describe, so hopefully you can tell me if it is abnormal and save me the postal fees and frustration of a denied replacement if this behaviour is not considered a fault.

I have tested using the attached file (trem_tri_80pc_5sec.wav). This file consists of a 440 hz tone that moves from 80 percent to 16 percent amplitude and back up to 80 percent again over a duration of 5 seconds, in a triangular pattern. This cycle repeats for the entire duration of the file (1 minute).

I set the volume on my audio device so that at the 80 percent peak of this file, the "100%" red light is lit. When it drops to 16%, only the "On" red light is lit. As the file progresses, the LEDs light up in sequence, exactly as you would expect, at exactly the timing that you would expect.

As the input amplitude rises, through the duration of the "25% (green)" LED, there is still zero output. Roughly 0.5 seconds after the "50% (green)" LED illuminates, there is a strong output. This output then remains at the same intensity (or with so little variation that it cannot be felt) as the LEDs move through the "75% (yellow)" and "100% (red)" lights. The file progresses and the input amplitude starts to reduce, the intensity again remains constant through the "100% (red)" light, through the "75% (yellow)" light, and for most of the illuminated period of the "50% (green)" light. Roughly 0.5 seconds before the "50% (green)" light ceases to be illuminated, the output cuts to zero.

I have the "output level" dial set to around 50% for this testing, and have tested increasing it to 100% for the duration of the "25% (green)" light - the output is zero.

Further testing with a constant 440 hz tone (that does not vary in amplitude) as input, and alternating the input level by using the volume of my audio device: Input LED at 25% - zero output. Input LED 50% illuminated - strong output, and I can very clearly feel the gradual change in intensity if I adjust the "output level" dial between 25% and 100%. "Input level" LEDs at 75% or 100% - pretty much exactly the same output as when the 50% LED is the maximum one that's illuminated.

I very much hope that this is not the expected behaviour, and it explains exactly what I felt in my first post regarding "test_mono.mp3". I believe that at the 43 second mark in that file the input signal is oscillating over the point at which my ABox goes from "no output" to "some output", and given that "some output" is indiscernible from "maximum output" in these tests, my body interprets that as painful, shocking 'thumps'.
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Re: ABox response and potential fault

Post by admin »

As I have said several times, firstly the human body is not a test instrument so your feelings and response to any signal are not going to be linear. The ABox does not have the capacity to 'edit' the waveform, it simply takes the input, converts it to a signal you can feel to produce an output in a consistent manner. Reduce the input and the output will reduce, change the frequency and the output frequency will change, whether you feel that as a change in sensation, or how you feel that change as a sensation is up to your body. Clearly the ABox is reacting to the changes on the input file - indicated by the LEDs, and there is no reason why the output generator will not react in a similar way, so it does appear that the ABox is working correctly, just you are not responding to the changing output it as you think you should. This is not uncommon, people are all different and we have people on our test team that feel nothing at X, everything between X and Y and then from Y despite the output going higher they feel no change. This is not unusual, this is the way the human body reacts with many many devices.

The solution? widen the range you adjust values, and ignore the exact values. (too many people get hung up on exact values and what works for others - just because someone likes 345Hz, does not mean you will. I know I keep coming back to music, but hardly any musician will work with discreet frequencies, that play an instrument to create emotion not a bunch of frequencies and amplitudes.

Try to change things to fit your feelings and sensations and build on what works for you. but given what you have said here and before I see no issue with the operation of the ABox.

Si
E-Stim Systems Ltd
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