Re: FOCUS EEG Amplifier Review

[Guest guest]

Pete,

I very much appreciated your review of the FOCUS but I am not

knowledgeable enough about the details of the signal processing issues

to assess the value of the FOCUS compared to the ProComp Infiniti I've

been working with, which seems to be doing a good job. If one is

already equipped with the ProComp Infiniti, what difference in terms of

quality of training, for example, would having the FOCUS make? Does the

FOCUS provide a clearer signal, by this I mean a signal that is more

representative of brain states with less distorsion, so that it is

easier for people to identify states they reach and reproduce them for

example?

Celine

[Guest guest]

Pete,

I very much appreciated your review of the FOCUS but I am not

knowledgeable enough about the details of the signal processing issues

to assess the value of the FOCUS compared to the ProComp Infiniti I've

been working with, which seems to be doing a good job. If one is

already equipped with the ProComp Infiniti, what difference in terms of

quality of training, for example, would having the FOCUS make? Does the

FOCUS provide a clearer signal, by this I mean a signal that is more

representative of brain states with less distorsion, so that it is

easier for people to identify states they reach and reproduce them for

example?

Celine

[Guest guest]

Celine,

Let me start with a summary answer for those who won't make it through all the stuff below: Just as I don't believe that one brain is better or more normal than another--each has its strengths and weaknesses--so I don't believe one amplifier is inherently better. The one you have, if you are getting results with it, is by definition doing the job you want it to do. My point about the Focus was simply this: For a remarkably low price, it offers superb signal processing (comparisons below) and it works in BioExplorer. If you already have Infiniti and are comfortable with the software, any new software will be a deterrant. For people already using BioExplorer or BioEra, getting a Focus requires no change in software at all. For those who are working as home trainers--or pros working with home trainers--the Focus may be an excellent option because of its signal quality, sturdiness and price. I'm not suggesting that anyone put their current system on E-Bay and run out to buy a Focus. I'm simply informing those who are interested on our list (and on the brain-trainer website) that this option is there, and that it is an excellent one.

This will be a bit of an apples/oranges comparison, since the Infiniti is a decoder with the option of training peripheral biofeedback modalities as well as EEG and price-wise is around 4 times the price of a Focus with BioExplorer. However, here are some differences as I see them at present:

Specs:

Analog/Digital conversion (the resolution achieved in converting analog/waveform signals to digital/numeric signals for use in the software; higher is better) the Infiniti operates at 14 bits; Focus at 16 bits. Both are probably above our ability to discern a difference.

Bandwidth/sampling rate (the number of times per second the amplifier gets samples of the EEG and the width of the band it can sample) Infiniti samples at 256 in a band up to 64 Hz wide. The lowest value is not specified in anything I have seen, so I assume it is, like most amplifiers, around 0.5 Hz. The Focus also samples at 256 in a band that starts at 0 Hz and runs to 128 Hz. Of course, since the Infiniti has separate channels dedicated to EMG, it can sample higher frequencies with those. The Focus can use a filter in the EEG software (set, for example from 70-120 Hz) to read very fast signal bursts which are likely to be EMG.

Encoder noise (the amount of signal produced by the amplifier internally when no signal is being input) Infiniti produces 1 millivolt measuring Peak-to-Peak. The Focus, as I showed in the images in the review, shows no internal signal even at the nanovolt scale.

Input impedance (the resistance on the front end of the system designed to filter out noise) The Infiniti places this in the Sensor/ preamp like the EEG-Z which must be plugged into a channel you wish to use for EEG in order to prepare the signal from the electrodes. The input impedance is listed as 10 giga ohms. The QDS philosophy has been to produce amplifiers (through individual hand-tuning) that output no measurable internal noise and to require excellent hookups from the trainer in order to operate with VERY low input impedances. The idea is that the high impedance through which the signal must pass not only screens out noise; it must also screen out part of the EEG signal. One result of this is that you don't need an impedance meter to evaluate hookup quality. If you have a poor connection--or if you have serious electromagnetic field issues--it is immediately apparent on the waveform display. A good hookup in a good environment gives a nice, thin, detailed and variable tracing; a bad signal looks like a caterpillar. One recent purchaser of a Focus reported this experience, having become accustomed to training with amplifiers with high input impedances. The signal he could ordinarily have trained was horrible on the Focus. He checked impedances and found they were in the 40's. He got them down below 10, and the signal was beautiful.

Hardware vs. software high/low pass filters (how the amplifier sets its range from lowest to highest measurable signal).Most amplifiers, like the Infiniti, include hardware filters which block all signals below, for example, 0.5 Hz and above, say, 64 Hz. The Focus, like the PET and QPET, does not include these hardware filters. Leaving them out allows the trainer to choose the band he/she wishes to see all the way down to 0 Hz (for very-low frequency training or Slow Cortical Potential training) or up to 128 Hz (for EMG, as discussed above). Second, because the filter allows the slower DC waves through, artifact from movement and eye movement causes the waveform to " wander " on the oscilloscope. 60 or 50 Hz electrcal field artifact is also immediately obvious, and you learn to get rid of it rather than training through it. Two Infiniti users who have started using Focus with home trainers have found that there was a strong field in their training areas. The EEG's looked fine, but clients generally had lots of fast activity and coherences were always high. With the Focus, they had to track down the source and resolve it, then their signals improved on ALL their amplifiers. Perhaps the strongest argument for this approach is that any filter causes signal delay. As you know, I always try to produce 250 ms (1/4 second) or less of delay with my training protocols, to minimize feedback latency. Filters are the largest single unremovable delay in most protocols. The front end filters through which the signal must pass slow it down somewhat; how much, I don't know. So using an amp without the hardware filters, one can always add software filters to do the job in front of the spectral display and the waveform display, if desired. BUT there is NO delay added to the actual TRAINING signal.

I hope this is helpful. And especially I hope that everyone understands that, just as my reviews of Pendants and Atlantis and PET's didn't mean I thought everyone should run out and buy those, I'm not suggesting that users should use nothing but Focus. If I thought that, we wouldn't sell other amplifiers on brain-trainer.com. And certainly the Focus can't--and isn't meant to--replace an Infiniti.

Pete

I very much appreciated your review of the FOCUS but I am not knowledgeable enough about the details of the signal processing issues to assess the value of the FOCUS compared to the ProComp Infiniti I've

been working with, which seems to be doing a good job. If one is already equipped with the ProComp Infiniti, what difference in terms of quality of training, for example, would having the FOCUS make? Does the

FOCUS provide a clearer signal, by this I mean a signal that is more representative of brain states with less distorsion, so that it is easier for people to identify states they reach and reproduce them for example?

..__ -- Van Deusenpvdtlc@...

http://www.brain-trainer.com305/433-3160The Learning Curve, Inc.

[Guest guest]

Celine,

Let me start with a summary answer for those who won't make it through all the stuff below: Just as I don't believe that one brain is better or more normal than another--each has its strengths and weaknesses--so I don't believe one amplifier is inherently better. The one you have, if you are getting results with it, is by definition doing the job you want it to do. My point about the Focus was simply this: For a remarkably low price, it offers superb signal processing (comparisons below) and it works in BioExplorer. If you already have Infiniti and are comfortable with the software, any new software will be a deterrant. For people already using BioExplorer or BioEra, getting a Focus requires no change in software at all. For those who are working as home trainers--or pros working with home trainers--the Focus may be an excellent option because of its signal quality, sturdiness and price. I'm not suggesting that anyone put their current system on E-Bay and run out to buy a Focus. I'm simply informing those who are interested on our list (and on the brain-trainer website) that this option is there, and that it is an excellent one.

This will be a bit of an apples/oranges comparison, since the Infiniti is a decoder with the option of training peripheral biofeedback modalities as well as EEG and price-wise is around 4 times the price of a Focus with BioExplorer. However, here are some differences as I see them at present:

Specs:

Analog/Digital conversion (the resolution achieved in converting analog/waveform signals to digital/numeric signals for use in the software; higher is better) the Infiniti operates at 14 bits; Focus at 16 bits. Both are probably above our ability to discern a difference.

Bandwidth/sampling rate (the number of times per second the amplifier gets samples of the EEG and the width of the band it can sample) Infiniti samples at 256 in a band up to 64 Hz wide. The lowest value is not specified in anything I have seen, so I assume it is, like most amplifiers, around 0.5 Hz. The Focus also samples at 256 in a band that starts at 0 Hz and runs to 128 Hz. Of course, since the Infiniti has separate channels dedicated to EMG, it can sample higher frequencies with those. The Focus can use a filter in the EEG software (set, for example from 70-120 Hz) to read very fast signal bursts which are likely to be EMG.

Encoder noise (the amount of signal produced by the amplifier internally when no signal is being input) Infiniti produces 1 millivolt measuring Peak-to-Peak. The Focus, as I showed in the images in the review, shows no internal signal even at the nanovolt scale.

Input impedance (the resistance on the front end of the system designed to filter out noise) The Infiniti places this in the Sensor/ preamp like the EEG-Z which must be plugged into a channel you wish to use for EEG in order to prepare the signal from the electrodes. The input impedance is listed as 10 giga ohms. The QDS philosophy has been to produce amplifiers (through individual hand-tuning) that output no measurable internal noise and to require excellent hookups from the trainer in order to operate with VERY low input impedances. The idea is that the high impedance through which the signal must pass not only screens out noise; it must also screen out part of the EEG signal. One result of this is that you don't need an impedance meter to evaluate hookup quality. If you have a poor connection--or if you have serious electromagnetic field issues--it is immediately apparent on the waveform display. A good hookup in a good environment gives a nice, thin, detailed and variable tracing; a bad signal looks like a caterpillar. One recent purchaser of a Focus reported this experience, having become accustomed to training with amplifiers with high input impedances. The signal he could ordinarily have trained was horrible on the Focus. He checked impedances and found they were in the 40's. He got them down below 10, and the signal was beautiful.

Hardware vs. software high/low pass filters (how the amplifier sets its range from lowest to highest measurable signal).Most amplifiers, like the Infiniti, include hardware filters which block all signals below, for example, 0.5 Hz and above, say, 64 Hz. The Focus, like the PET and QPET, does not include these hardware filters. Leaving them out allows the trainer to choose the band he/she wishes to see all the way down to 0 Hz (for very-low frequency training or Slow Cortical Potential training) or up to 128 Hz (for EMG, as discussed above). Second, because the filter allows the slower DC waves through, artifact from movement and eye movement causes the waveform to " wander " on the oscilloscope. 60 or 50 Hz electrcal field artifact is also immediately obvious, and you learn to get rid of it rather than training through it. Two Infiniti users who have started using Focus with home trainers have found that there was a strong field in their training areas. The EEG's looked fine, but clients generally had lots of fast activity and coherences were always high. With the Focus, they had to track down the source and resolve it, then their signals improved on ALL their amplifiers. Perhaps the strongest argument for this approach is that any filter causes signal delay. As you know, I always try to produce 250 ms (1/4 second) or less of delay with my training protocols, to minimize feedback latency. Filters are the largest single unremovable delay in most protocols. The front end filters through which the signal must pass slow it down somewhat; how much, I don't know. So using an amp without the hardware filters, one can always add software filters to do the job in front of the spectral display and the waveform display, if desired. BUT there is NO delay added to the actual TRAINING signal.

I hope this is helpful. And especially I hope that everyone understands that, just as my reviews of Pendants and Atlantis and PET's didn't mean I thought everyone should run out and buy those, I'm not suggesting that users should use nothing but Focus. If I thought that, we wouldn't sell other amplifiers on brain-trainer.com. And certainly the Focus can't--and isn't meant to--replace an Infiniti.

Pete

I very much appreciated your review of the FOCUS but I am not knowledgeable enough about the details of the signal processing issues to assess the value of the FOCUS compared to the ProComp Infiniti I've

been working with, which seems to be doing a good job. If one is already equipped with the ProComp Infiniti, what difference in terms of quality of training, for example, would having the FOCUS make? Does the

FOCUS provide a clearer signal, by this I mean a signal that is more representative of brain states with less distorsion, so that it is easier for people to identify states they reach and reproduce them for example?

..__ -- Van Deusenpvdtlc@...

http://www.brain-trainer.com305/433-3160The Learning Curve, Inc.

[Guest guest]

Pete,

Thank you so much for the very clear explanation, it went a long way

into deepening my comprehension of hardware functionality issues. The

delay to the training signal part was what prompted my question.

Celine

> >

> > I very much appreciated your review of the FOCUS but I am not

> > knowledgeable enough about the details of the signal processing

issues

> > to assess the value of the FOCUS compared to the ProComp Infiniti

I've

> > been working with, which seems to be doing a good job. If one is

> > already equipped with the ProComp Infiniti, what difference in

terms of

> > quality of training, for example, would having the FOCUS make?

Does the

> > FOCUS provide a clearer signal, by this I mean a signal that is

more

> > representative of brain states with less distorsion, so that it

is easier

> > for people to identify states they reach and reproduce them for

example?

> > .

> > __

> >

>

> --

> Van Deusen

> pvdtlc@...

> http://www.brain-trainer.com

> 305/433-3160

> The Learning Curve, Inc.

>

[Guest guest]

Don,

Sorry for the delay in responding to your correction. I did not mention specs for Infiniti in my review, only in an answer to a question regarding Infiniti. Apologies for any errors, but the information was taken from Thought Tech specifications I found on the internet (http://bio-medical.com/product_info.cfm?inventory__imodel=T7170M) from a Thought Tech distributor.

As you know, the Infiniti has 2 fast channels (A and , primarily for EMG. They do indeed sample at 2048, which is appropriate for the much high frequencies found in EMG signals. The " Slow Channels " , which would be C through H that are used for EEG, sample at 256, as do most EEG amplifiers. The encoder bandwidth is shown as 64 Hz @ 256 samples/second. Once again, the two non-EEG channels that sample at 2048 Hz do indeed have a bandwidth of 512 Hz, but those should not be used for EEG training.

I'm glad to hear that there is a SCP front end for Infiniti. I was not aware of that. I assume that works with the EEG Channels.

I will adjust my statement about the highest amplitude that can be read by the Focus from 128 Hz to 127 Hz (since no-one will be reading up that high in BioExplorer anyway). That puts it below the Nyquist rate.

I don't work for QDS or Thought Technology either, though I have and use both their amplifiers.

Thanks for keeping me honest. I too would not want people to make buying decisions based on misinformation--especially from me.

Pete

;

Your review of the Infinity has some significant errors.

Sample rate / bandwidth: for eeg, emg 2048 s/s

Bandwidth DC - 512 hz.

They do have dc front ends for SCP

Filters:

While I agree with your logic, You did not say that above the nyquist limit analog conversion will result in artifacts in the signal. You stated that the focus sampled at 256 and had a bandwidth to 128. That is over the nyquist limit, so you are guaranteed distortion in the signal.

With a 512 HZ top end, it is unlikely that the Infinity filter will have any effect anyway.

What you said about the 60 HZ filter is very important. Normally, however you can see 60 HZ interference even with the filter. But, you have to look for it. Making it more blatant is not a bad thing.

Finally, I do not work for TT. I went to their web sit and pulled up the specifications page.

It concerns me when people make statements that are incorrect that other people will use to make purchasing decisions with.

Don Wilde, Ph.D.

.. -- Van Deusenpvdtlc@...http://www.brain-trainer.com

305/433-3160The Learning Curve, Inc.

[Guest guest]

;

I suggest you use the Thought Technology website. They explicitly state that the 2048 s/s A & B channels may be used with EEG. Just to be sure, I emailed to confirm. This is the response:

Hi Don

You can definitely use the first 2 channels. The only concern is that the higher sampling rate may produce slightly different results than the other slower channels, so using one of them for coherence or phase comparisons to the slower channels might not be advisable; however, this is more theoretical than tested.

Hal

I am astounded that Bio-Medical's web site is that incorrect.

I do not understand why you say they (A & "should not be used for NF training" Its pretty hard to train high Beta with a 256 sample rate. Even my old Lexicor had a 512 sample rate available. And you yourself are arguing for a higher (127 HZ) bandwidth. So what about a clean 0-512 Hz.?

Don Wilde

Re: Re: FOCUS EEG Amplifier Review

Don,

Sorry for the delay in responding to your correction. I did not mention specs for Infiniti in my review, only in an answer to a question regarding Infiniti. Apologies for any errors, but the information was taken from Thought Tech specifications I found on the internet (http://bio-medical.com/product_info.cfm?inventory__imodel=T7170M) from a Thought Tech distributor.

As you know, the Infiniti has 2 fast channels (A and , primarily for EMG. They do indeed sample at 2048, which is appropriate for the much high frequencies found in EMG signals. The "Slow Channels", which would be C through H that are used for EEG, sample at 256, as do most EEG amplifiers. The encoder bandwidth is shown as 64 Hz @ 256 samples/second. Once again, the two non-EEG channels that sample at 2048 Hz do indeed have a bandwidth of 512 Hz, but those should not be used for EEG training.

I'm glad to hear that there is a SCP front end for Infiniti. I was not aware of that. I assume that works with the EEG Channels.

I will adjust my statement about the highest amplitude that can be read by the Focus from 128 Hz to 127 Hz (since no-one will be reading up that high in BioExplorer anyway). That puts it below the Nyquist rate.

I don't work for QDS or Thought Technology either, though I have and use both their amplifiers.

Thanks for keeping me honest. I too would not want people to make buying decisions based on misinformation--especially from me.

Pete

On Fri, Feb 29, 2008 at 7:26 PM, Don Wilde <donwildehughes (DOT) net> wrote:

;

Your review of the Infinity has some significant errors.

Sample rate / bandwidth: for eeg, emg 2048 s/s

Bandwidth DC - 512 hz.

They do have dc front ends for SCP

Filters:

While I agree with your logic, You did not say that above the nyquist limit analog conversion will result in artifacts in the signal. You stated that the focus sampled at 256 and had a bandwidth to 128. That is over the nyquist limit, so you are guaranteed distortion in the signal.

With a 512 HZ top end, it is unlikely that the Infinity filter will have any effect anyway.

What you said about the 60 HZ filter is very important. Normally, however you can see 60 HZ interference even with the filter. But, you have to look for it. Making it more blatant is not a bad thing.

Finally, I do not work for TT. I went to their web sit and pulled up the specifications page.

It concerns me when people make statements that are incorrect that other people will use to make purchasing decisions with.

Don Wilde, Ph.D.

.. -- Van Deusenpvdtlcgmailhttp://www.brain-trainer.com305/433-3160The Learning Curve, Inc.

[Guest guest]

Don,

Once again, you are responding to an answer I tried to provide to a Thought Technology user who asked about a comparison of the Focus, which was the unit I reviewed, and the Infiniti, which I don't think was mentioned in the review. I'm glad to learn that the 2048 Hz channels can be used for EEG. I suppose you could also use a BMW to pull out stumps if you wanted to, but that's not what it's designed for.

The Thought Tech site itself says:

" The first two sensor channels provide ultimate signal fidelity (2048 samples per second) for viewing RAW EEG, EMG and EKG signals. The remaining six channels (256 samples/sec) can be used with any combination of sensors, including EEG, EKG, RMS EMG, skin conductance, heart rate, blood volume pulse, respiration, goniometry, force, and voltage input. "

I have done workshops on the Thought Technology equipment for BioFeedback Europe. I own an Infiniti amp and work with the software (doing the TLC Assessment). There are a number of Infiniti users on this list. I'd be very interested in how many of them are using the A and B channels for EEG training. Everything I've ever heard is that C-H are the EEG channels. They sample at 256, like the Focus and most other EEG amps Higher sampling rates tend to change the morphology of the EEG tracing and, as Hal's response to you indicated, would very likely make the A and B channels not very comparable with the others. Thus you would end up with a 2-channel EEG amplifier--instead of a 6-channel.

You yourself mentioned mentioned the Nyquist Theorem. So assuming you wanted to train gamma--maybe all the way up to 49 Hz, where you would start running into EMG--a sampling rate of 100 sample/second would fulfill the requirement. Certainly 256 would be a bit better in terms of resolution of the higher frequencies--not just 2 times the frequency but FIVE times the frequency. So one would assume training (down, I hope) high beta up to 38 Hz would be no problem whatsoever with a 256 sps machine.

So, once again, I'm not saying anything bad about Infiniti. I was trying, based on my experience and the information I was able to find (and I did go to the Thought Tech website) to give a comparison of printed specs between the two machines.

Pete

I suggest you use the Thought Technology website. They explicitly state that the 2048 s/s A & B channels may be used with EEG. Just to be sure, I emailed to confirm. This is the response:

You can definitely use the first 2 channels. The only concern is that the higher sampling rate may produce slightly different results than the other slower channels, so using one of them for coherence or phase comparisons to the slower channels might not be advisable; however, this is more theoretical than tested.

Hal

I am astounded that Bio-Medical's web site is that incorrect.

I do not understand why you say they (A & " should not be used for NF training " Its pretty hard to train high Beta with a 256 sample rate. Even my old Lexicor had a 512 sample rate available. And you yourself are arguing for a higher (127 HZ) bandwidth. So what about a clean 0-512 Hz.?

..-- Van Deusenpvdtlc@...

http://www.brain-trainer.com305/433-3160The Learning Curve, Inc.

[Guest guest]

The channels used for EEG In Infinity depend upon the suite used and whether you set the use for Procomp+ or Procomp Infinity. By and large P+ suites use channels A and B . Pocomp Infinity suites use channels C and D. I dont' know what happens if you develop your own suites.. You may be able to use Procomp Infinity with channesl A and B for EEG.

Mark

Re: Re: FOCUS EEG Amplifier Review

Don,

Once again, you are responding to an answer I tried to provide to a Thought Technology user who asked about a comparison of the Focus, which was the unit I reviewed, and the Infiniti, which I don't think was mentioned in the review. I'm glad to learn that the 2048 Hz channels can be used for EEG. I suppose you could also use a BMW to pull out stumps if you wanted to, but that's not what it's designed for.

The Thought Tech site itself says:

"The first two sensor channels provide ultimate signal fidelity (2048 samples per second) for viewing RAW EEG, EMG and EKG signals. The remaining six channels (256 samples/sec) can be used with any combination of sensors, including EEG, EKG, RMS EMG, skin conductance, heart rate, blood volume pulse, respiration, goniometry, force, and voltage input."

I have done workshops on the Thought Technology equipment for BioFeedback Europe. I own an Infiniti amp and work with the software (doing the TLC Assessment). There are a number of Infiniti users on this list. I'd be very interested in how many of them are using the A and B channels for EEG training. Everything I've ever heard is that C-H are the EEG channels. They sample at 256, like the Focus and most other EEG amps Higher sampling rates tend to change the morphology of the EEG tracing and, as Hal's response to you indicated, would very likely make the A and B channels not very comparable with the others. Thus you would end up with a 2-channel EEG amplifier--instead of a 6-channel.

You yourself mentioned mentioned the Nyquist Theorem. So assuming you wanted to train gamma--maybe all the way up to 49 Hz, where you would start running into EMG--a sampling rate of 100 sample/second would fulfill the requirement. Certainly 256 would be a bit better in terms of resolution of the higher frequencies--not just 2 times the frequency but FIVE times the frequency. So one would assume training (down, I hope) high beta up to 38 Hz would be no problem whatsoever with a 256 sps machine.

So, once again, I'm not saying anything bad about Infiniti. I was trying, based on my experience and the information I was able to find (and I did go to the Thought Tech website) to give a comparison of printed specs between the two machines.

Pete

On Fri, Mar 21, 2008 at 6:05 PM, Don Wilde <donwildehughes (DOT) net> wrote:

I suggest you use the Thought Technology website. They explicitly state that the 2048 s/s A & B channels may be used with EEG. Just to be sure, I emailed to confirm. This is the response:

You can definitely use the first 2 channels. The only concern is that the higher sampling rate may produce slightly different results than the other slower channels, so using one of them for coherence or phase comparisons to the slower channels might not be advisable; however, this is more theoretical than tested.

Hal

I am astounded that Bio-Medical's web site is that incorrect.

I do not understand why you say they (A & "should not be used for NF training" Its pretty hard to train high Beta with a 256 sample rate. Even my old Lexicor had a 512 sample rate available. And you yourself are arguing for a higher (127 HZ) bandwidth. So what about a clean 0-512 Hz.?

..-- Van Deusenpvdtlcgmailhttp://www.brain-trainer.com305/433-3160The Learning Curve, Inc.

[Guest guest]

The channels used for EEG In Infinity depend upon the suite used and whether you set the use for Procomp+ or Procomp Infinity. By and large P+ suites use channels A and B . Pocomp Infinity suites use channels C and D. I dont' know what happens if you develop your own suites.. You may be able to use Procomp Infinity with channesl A and B for EEG.

Mark

Re: Re: FOCUS EEG Amplifier Review

Don,

Once again, you are responding to an answer I tried to provide to a Thought Technology user who asked about a comparison of the Focus, which was the unit I reviewed, and the Infiniti, which I don't think was mentioned in the review. I'm glad to learn that the 2048 Hz channels can be used for EEG. I suppose you could also use a BMW to pull out stumps if you wanted to, but that's not what it's designed for.

The Thought Tech site itself says:

"The first two sensor channels provide ultimate signal fidelity (2048 samples per second) for viewing RAW EEG, EMG and EKG signals. The remaining six channels (256 samples/sec) can be used with any combination of sensors, including EEG, EKG, RMS EMG, skin conductance, heart rate, blood volume pulse, respiration, goniometry, force, and voltage input."

I have done workshops on the Thought Technology equipment for BioFeedback Europe. I own an Infiniti amp and work with the software (doing the TLC Assessment). There are a number of Infiniti users on this list. I'd be very interested in how many of them are using the A and B channels for EEG training. Everything I've ever heard is that C-H are the EEG channels. They sample at 256, like the Focus and most other EEG amps Higher sampling rates tend to change the morphology of the EEG tracing and, as Hal's response to you indicated, would very likely make the A and B channels not very comparable with the others. Thus you would end up with a 2-channel EEG amplifier--instead of a 6-channel.

You yourself mentioned mentioned the Nyquist Theorem. So assuming you wanted to train gamma--maybe all the way up to 49 Hz, where you would start running into EMG--a sampling rate of 100 sample/second would fulfill the requirement. Certainly 256 would be a bit better in terms of resolution of the higher frequencies--not just 2 times the frequency but FIVE times the frequency. So one would assume training (down, I hope) high beta up to 38 Hz would be no problem whatsoever with a 256 sps machine.

So, once again, I'm not saying anything bad about Infiniti. I was trying, based on my experience and the information I was able to find (and I did go to the Thought Tech website) to give a comparison of printed specs between the two machines.

Pete

On Fri, Mar 21, 2008 at 6:05 PM, Don Wilde <donwildehughes (DOT) net> wrote:

I suggest you use the Thought Technology website. They explicitly state that the 2048 s/s A & B channels may be used with EEG. Just to be sure, I emailed to confirm. This is the response:

You can definitely use the first 2 channels. The only concern is that the higher sampling rate may produce slightly different results than the other slower channels, so using one of them for coherence or phase comparisons to the slower channels might not be advisable; however, this is more theoretical than tested.

Hal

I am astounded that Bio-Medical's web site is that incorrect.

I do not understand why you say they (A & "should not be used for NF training" Its pretty hard to train high Beta with a 256 sample rate. Even my old Lexicor had a 512 sample rate available. And you yourself are arguing for a higher (127 HZ) bandwidth. So what about a clean 0-512 Hz.?

..-- Van Deusenpvdtlcgmailhttp://www.brain-trainer.com305/433-3160The Learning Curve, Inc.

[Guest guest]

The channels used for EEG In Infinity depend upon the suite used and whether you set the use for Procomp+ or Procomp Infinity. By and large P+ suites use channels A and B . Pocomp Infinity suites use channels C and D. I dont' know what happens if you develop your own suites.. You may be able to use Procomp Infinity with channesl A and B for EEG.

Mark

Re: Re: FOCUS EEG Amplifier Review

Don,

Once again, you are responding to an answer I tried to provide to a Thought Technology user who asked about a comparison of the Focus, which was the unit I reviewed, and the Infiniti, which I don't think was mentioned in the review. I'm glad to learn that the 2048 Hz channels can be used for EEG. I suppose you could also use a BMW to pull out stumps if you wanted to, but that's not what it's designed for.

The Thought Tech site itself says:

"The first two sensor channels provide ultimate signal fidelity (2048 samples per second) for viewing RAW EEG, EMG and EKG signals. The remaining six channels (256 samples/sec) can be used with any combination of sensors, including EEG, EKG, RMS EMG, skin conductance, heart rate, blood volume pulse, respiration, goniometry, force, and voltage input."

I have done workshops on the Thought Technology equipment for BioFeedback Europe. I own an Infiniti amp and work with the software (doing the TLC Assessment). There are a number of Infiniti users on this list. I'd be very interested in how many of them are using the A and B channels for EEG training. Everything I've ever heard is that C-H are the EEG channels. They sample at 256, like the Focus and most other EEG amps Higher sampling rates tend to change the morphology of the EEG tracing and, as Hal's response to you indicated, would very likely make the A and B channels not very comparable with the others. Thus you would end up with a 2-channel EEG amplifier--instead of a 6-channel.

You yourself mentioned mentioned the Nyquist Theorem. So assuming you wanted to train gamma--maybe all the way up to 49 Hz, where you would start running into EMG--a sampling rate of 100 sample/second would fulfill the requirement. Certainly 256 would be a bit better in terms of resolution of the higher frequencies--not just 2 times the frequency but FIVE times the frequency. So one would assume training (down, I hope) high beta up to 38 Hz would be no problem whatsoever with a 256 sps machine.

So, once again, I'm not saying anything bad about Infiniti. I was trying, based on my experience and the information I was able to find (and I did go to the Thought Tech website) to give a comparison of printed specs between the two machines.

Pete

On Fri, Mar 21, 2008 at 6:05 PM, Don Wilde <donwildehughes (DOT) net> wrote:

I suggest you use the Thought Technology website. They explicitly state that the 2048 s/s A & B channels may be used with EEG. Just to be sure, I emailed to confirm. This is the response:

You can definitely use the first 2 channels. The only concern is that the higher sampling rate may produce slightly different results than the other slower channels, so using one of them for coherence or phase comparisons to the slower channels might not be advisable; however, this is more theoretical than tested.

Hal

I am astounded that Bio-Medical's web site is that incorrect.

I do not understand why you say they (A & "should not be used for NF training" Its pretty hard to train high Beta with a 256 sample rate. Even my old Lexicor had a 512 sample rate available. And you yourself are arguing for a higher (127 HZ) bandwidth. So what about a clean 0-512 Hz.?

..-- Van Deusenpvdtlcgmailhttp://www.brain-trainer.com305/433-3160The Learning Curve, Inc.

[Guest guest]

Mark,

You are correct. On the ProComp, the 256 samples per second channels do start with A and B. The Infiniti has the two fast channels in A and B.

Pete

The channels used for EEG In Infinity depend upon the suite used and whether you set the use for Procomp+ or Procomp Infinity. By and large P+ suites use channels A and B . Pocomp Infinity suites use channels C and D. I dont' know what happens if you develop your own suites.. You may be able to use Procomp Infinity with channesl A and B for EEG.

Mark

.. -- Van Deusenpvdtlc@...

http://www.brain-trainer.com305/433-3160The Learning Curve, Inc.

[Guest guest]

Dear Mark,

Didier developed suites for me for the A and B channels for Procomp Infinity. I use it with one client training and very high frequencies.

Merlyn

Re: Re: FOCUS EEG Amplifier Review

Mark,

You are correct. On the ProComp, the 256 samples per second channels do start with A and B. The Infiniti has the two fast channels in A and B.

Pete

The channels used for EEG In Infinity depend upon the suite used and whether you set the use for Procomp+ or Procomp Infinity. By and large P+ suites use channels A and B . Pocomp Infinity suites use channels C and D. I dont' know what happens if you develop your own suites.. You may be able to use Procomp Infinity with channesl A and B for EEG.

Mark

..

--

Van Deusen

pvdtlc@...

http://www.brain-trainer.com

305/433-3160

The Learning Curve, Inc.

Planning your summer road trip? Check out AOL Travel Guides.

[Guest guest]

Dear Mark,

Didier developed suites for me for the A and B channels for Procomp Infinity. I use it with one client training and very high frequencies.

Merlyn

Re: Re: FOCUS EEG Amplifier Review

Mark,

You are correct. On the ProComp, the 256 samples per second channels do start with A and B. The Infiniti has the two fast channels in A and B.

Pete

The channels used for EEG In Infinity depend upon the suite used and whether you set the use for Procomp+ or Procomp Infinity. By and large P+ suites use channels A and B . Pocomp Infinity suites use channels C and D. I dont' know what happens if you develop your own suites.. You may be able to use Procomp Infinity with channesl A and B for EEG.

Mark

..

--

Van Deusen

pvdtlc@...

http://www.brain-trainer.com

305/433-3160

The Learning Curve, Inc.

Planning your summer road trip? Check out AOL Travel Guides.

[Guest guest]

Dear Mark,

Didier developed suites for me for the A and B channels for Procomp Infinity. I use it with one client training and very high frequencies.

Merlyn

Re: Re: FOCUS EEG Amplifier Review

Mark,

You are correct. On the ProComp, the 256 samples per second channels do start with A and B. The Infiniti has the two fast channels in A and B.

Pete

The channels used for EEG In Infinity depend upon the suite used and whether you set the use for Procomp+ or Procomp Infinity. By and large P+ suites use channels A and B . Pocomp Infinity suites use channels C and D. I dont' know what happens if you develop your own suites.. You may be able to use Procomp Infinity with channesl A and B for EEG.

Mark

..

--

Van Deusen

pvdtlc@...

http://www.brain-trainer.com

305/433-3160

The Learning Curve, Inc.

Planning your summer road trip? Check out AOL Travel Guides.

[Guest guest]

AHA!!! yes I do see " wide band inhibit " screens, but they all say C+D,

therefore I thought they would be limited to two-channel training.

However I will take your advice and let channel D lie there passively

if that's " allowed " .

Thanks!

Liz

> > >

> > > > I suggest you use the Thought Technology website. They

explicitly

> > > > state that the 2048 s/s A & B channels may be used with EEG. Just

> > to be sure,

> > > > I emailed to confirm. This is the response:

> > > >

> > > > You can definitely use the first 2 channels. The only concern is

> > that the

> > > > higher sampling rate may produce slightly different results than

> > the other

> > > > slower channels, so using one of them for coherence or phase

> > comparisons to

> > > > the slower channels might not be advisable; however, this is

more

> > > > theoretical than tested.

> > > >

> > > > Hal

> > > >

> > > > I am astounded that Bio-Medical's web site is that incorrect.

> > > >

> > > > I do not understand why you say they (A & " should not be used

> for NF

> > > > training " Its pretty hard to train high Beta with a 256 sample

> > rate. Even

> > > > my old Lexicor had a 512 sample rate available. And you

> yourself are

> > > > arguing for a higher (127 HZ) bandwidth. So what about a clean

> > 0-512 Hz.?

> > > > .

> > > >

> > > >

> > >

> > >

> > > --

> > > Van Deusen

> > > pvdtlc@

> > > http://www.brain-trainer.com

> > > 305/433-3160

> > > The Learning Curve, Inc.

> > >

> >

>

[Guest guest]

Mark,

responding to this:

You may be able to use Procomp Infinity with channesl A and B for EEG.

> Mark

Yes, you can, by switching the " encoder " setting from " Infiniti "

(spelled with an i, not a y -- not a real word; rather, a brand name)

to Legacy. That's exactly what my former teacher Harry was

doing when he began my own training. Later on at the s' course

the Thought Technology consultant " " told me that was ridiculous

(his opinion). Why go backwards? he said (we were not doing general

feedback; we were doing neurofeedback). The Infiniti is supposed

to be an improvement over the ProComp+. (in other words, as I

understand it, the Infiniti's " Legacy " IS ProComp+)

HOWEVER there is something else!

When I switched from the " Legacy " the the " Infiniti " encoder, the

machine didn't work --- and I finally figured out why.

There are those tiny switches on the back (bottom? I can't remember)

of the machine where you have to choose 0 or 1 for each switch. The

arrangement of those 0-or-1 switches is different for the Infiniti

from the Legacy!

I am just saying this because I went through the experience of Harry

setting up those switches for the Legacy encoder, and they

had to be changed when I " upgraded " to the Infiniti encoder.

So just saying, that is another factor if anyone here is going to be

switching encoders to make use of different channels -- you have to

remember to reset your little switches!

Liz

[Guest guest]

Mark,

responding to this:

You may be able to use Procomp Infinity with channesl A and B for EEG.

> Mark

Yes, you can, by switching the " encoder " setting from " Infiniti "

(spelled with an i, not a y -- not a real word; rather, a brand name)

to Legacy. That's exactly what my former teacher Harry was

doing when he began my own training. Later on at the s' course

the Thought Technology consultant " " told me that was ridiculous

(his opinion). Why go backwards? he said (we were not doing general

feedback; we were doing neurofeedback). The Infiniti is supposed

to be an improvement over the ProComp+. (in other words, as I

understand it, the Infiniti's " Legacy " IS ProComp+)

HOWEVER there is something else!

When I switched from the " Legacy " the the " Infiniti " encoder, the

machine didn't work --- and I finally figured out why.

There are those tiny switches on the back (bottom? I can't remember)

of the machine where you have to choose 0 or 1 for each switch. The

arrangement of those 0-or-1 switches is different for the Infiniti

from the Legacy!

I am just saying this because I went through the experience of Harry

setting up those switches for the Legacy encoder, and they

had to be changed when I " upgraded " to the Infiniti encoder.

So just saying, that is another factor if anyone here is going to be

switching encoders to make use of different channels -- you have to

remember to reset your little switches!

Liz

[Guest guest]

Liz

You don't even have to plug channel D in if you are using only channel C. You will find thta Channel C screens do mainly if not only beta training and I channel D screens right hemisphere traing such as SMR/low beta and alpha.

Mark

Re: FOCUS EEG Amplifier Review

AHA!!! yes I do see "wide band inhibit" screens, but they all say C+D,therefore I thought they would be limited to two-channel training.However I will take your advice and let channel D lie there passivelyif that's "allowed".Thanks!Liz> > > > > > > I suggest you use the Thought Technology website. Theyexplicitly> > > > state that the 2048 s/s A & B channels may be used with EEG. Just> > to be sure,> > > > I emailed to confirm. This is the response:> > > >> > > > You can definitely use the first 2 channels. The only concern is> > that the> > > > higher sampling rate may produce slightly different results than> > the other> > > > slower channels, so using one of them for coherence or phase> > comparisons to> > > > the slower channels might not be advisable; however, this ismore> > > > theoretical than tested.> > > >> > > > Hal> > > >> > > > I am astounded that Bio-Medical's web site is that incorrect.> > > >> > > > I do not understand why you say they (A & "should not be used> for NF> > > > training" Its pretty hard to train high Beta with a 256 sample> > rate. Even> > > > my old Lexicor had a 512 sample rate available. And you> yourself are> > > > arguing for a higher (127 HZ) bandwidth. So what about a clean> > 0-512 Hz.?> > > > .> > > >> > > >> > > > > > > > > -- > > > Van Deusen> > > pvdtlc@> > > http://www.brain-trainer.com> > > 305/433-3160> > > The Learning Curve, Inc.> > >> >>

[Guest guest]

Liz

You don't even have to plug channel D in if you are using only channel C. You will find thta Channel C screens do mainly if not only beta training and I channel D screens right hemisphere traing such as SMR/low beta and alpha.

Mark

Re: FOCUS EEG Amplifier Review

AHA!!! yes I do see "wide band inhibit" screens, but they all say C+D,therefore I thought they would be limited to two-channel training.However I will take your advice and let channel D lie there passivelyif that's "allowed".Thanks!Liz> > > > > > > I suggest you use the Thought Technology website. Theyexplicitly> > > > state that the 2048 s/s A & B channels may be used with EEG. Just> > to be sure,> > > > I emailed to confirm. This is the response:> > > >> > > > You can definitely use the first 2 channels. The only concern is> > that the> > > > higher sampling rate may produce slightly different results than> > the other> > > > slower channels, so using one of them for coherence or phase> > comparisons to> > > > the slower channels might not be advisable; however, this ismore> > > > theoretical than tested.> > > >> > > > Hal> > > >> > > > I am astounded that Bio-Medical's web site is that incorrect.> > > >> > > > I do not understand why you say they (A & "should not be used> for NF> > > > training" Its pretty hard to train high Beta with a 256 sample> > rate. Even> > > > my old Lexicor had a 512 sample rate available. And you> yourself are> > > > arguing for a higher (127 HZ) bandwidth. So what about a clean> > 0-512 Hz.?> > > > .> > > >> > > >> > > > > > > > > -- > > > Van Deusen> > > pvdtlc@> > > http://www.brain-trainer.com> > > 305/433-3160> > > The Learning Curve, Inc.> > >> >>

[Guest guest]

Liz

You don't even have to plug channel D in if you are using only channel C. You will find thta Channel C screens do mainly if not only beta training and I channel D screens right hemisphere traing such as SMR/low beta and alpha.

Mark

Re: FOCUS EEG Amplifier Review

AHA!!! yes I do see "wide band inhibit" screens, but they all say C+D,therefore I thought they would be limited to two-channel training.However I will take your advice and let channel D lie there passivelyif that's "allowed".Thanks!Liz> > > > > > > I suggest you use the Thought Technology website. Theyexplicitly> > > > state that the 2048 s/s A & B channels may be used with EEG. Just> > to be sure,> > > > I emailed to confirm. This is the response:> > > >> > > > You can definitely use the first 2 channels. The only concern is> > that the> > > > higher sampling rate may produce slightly different results than> > the other> > > > slower channels, so using one of them for coherence or phase> > comparisons to> > > > the slower channels might not be advisable; however, this ismore> > > > theoretical than tested.> > > >> > > > Hal> > > >> > > > I am astounded that Bio-Medical's web site is that incorrect.> > > >> > > > I do not understand why you say they (A & "should not be used> for NF> > > > training" Its pretty hard to train high Beta with a 256 sample> > rate. Even> > > > my old Lexicor had a 512 sample rate available. And you> yourself are> > > > arguing for a higher (127 HZ) bandwidth. So what about a clean> > 0-512 Hz.?> > > > .> > > >> > > >> > > > > > > > > -- > > > Van Deusen> > > pvdtlc@> > > http://www.brain-trainer.com> > > 305/433-3160> > > The Learning Curve, Inc.> > >> >>

[Guest guest]

Mark,

I'm not using a channel C or channel D screen. I'm using a two-channel

(C+D) screen, but I'm only using one channel © because the protocol

is one-channel wide-band inhibit.

When Jill was telling me to plug in D but not connect it to the head,

she was answering the question, " how can I use only one channel © of

a two-channel screen, since there are no one-channel screens that do

what I need? "

If I haven't understood you, I'm sorry.

Liz

> > > >

> > > > > I suggest you use the Thought Technology website. They

> explicitly

> > > > > state that the 2048 s/s A & B channels may be used with EEG.

Just

> > > to be sure,

> > > > > I emailed to confirm. This is the response:

> > > > >

> > > > > You can definitely use the first 2 channels. The only

concern is

> > > that the

> > > > > higher sampling rate may produce slightly different

results than

> > > the other

> > > > > slower channels, so using one of them for coherence or phase

> > > comparisons to

> > > > > the slower channels might not be advisable; however, this is

> more

> > > > > theoretical than tested.

> > > > >

> > > > > Hal

> > > > >

> > > > > I am astounded that Bio-Medical's web site is that incorrect.

> > > > >

> > > > > I do not understand why you say they (A & " should not be used

> > for NF

> > > > > training " Its pretty hard to train high Beta with a 256 sample

> > > rate. Even

> > > > > my old Lexicor had a 512 sample rate available. And you

> > yourself are

> > > > > arguing for a higher (127 HZ) bandwidth. So what about a clean

> > > 0-512 Hz.?

> > > > > .

> > > > >

> > > > >

> > > >

> > > >

> > > > --

> > > > Van Deusen

> > > > pvdtlc@

> > > > http://www.brain-trainer.com

> > > > 305/433-3160

> > > > The Learning Curve, Inc.

> > > >

> > >

> >

>

[Guest guest]

If you do this, I would not just leave the electrodes sitting on the desk. I would short them together (just connect one inside the other with a little dab of paste) to keep them from picking up a signal from the environment.

Pete

I'm not using a channel C or channel D screen. I'm using a two-channel(C+D) screen, but I'm only using one channel © because the protocolis one-channel wide-band inhibit. When Jill was telling me to plug in D but not connect it to the head,

she was answering the question, " how can I use only one channel © ofa two-channel screen, since there are no one-channel screens that dowhat I need? "

..-- Van Deusenpvdtlc@...http://www.brain-trainer.com

305/433-3160The Learning Curve, Inc.

[Guest guest]

Pete,

It’s not the electrodes which

are left on the desk – it’s just the amp with no electrodes

attached. If the amp is quiet, I don’t get any environmental signal.

Jill

From: braintrainer [mailto:braintrainer ] On Behalf Of Van Deusen

Sent: Friday, March 28, 2008 7:16

AM

To: braintrainer

Subject: Re: Re:

FOCUS EEG Amplifier Review

If you do this, I would not just leave the electrodes sitting on the

desk. I would short them together (just connect one inside the other with

a little dab of paste) to keep them from picking up a signal from the

environment.

Pete

On Fri, Mar 28, 2008 at 10:47 AM, lizmargoshes <drmargoshesgmail> wrote:

I'm not using a channel C or channel D screen. I'm

using a two-channel

(C+D) screen, but I'm only using one channel © because the protocol

is one-channel wide-band inhibit.

When Jill was telling me to plug in D but not connect it to the head,

she was answering the question, " how can I use only one channel © of

a two-channel screen, since there are no one-channel screens that do

what I need? "

..

--

Van Deusen

pvdtlcgmail

http://www.brain-trainer.com

305/433-3160

The Learning Curve, Inc.

[Guest guest]

Jill,

Got it.

Pete

It's not the electrodes which are left on the desk – it's just the amp with no electrodes attached. If the amp is quiet, I don't get any environmental signal.

..,___ -- Van Deusenpvdtlc@...

http://www.brain-trainer.com305/433-3160The Learning Curve, Inc.