FOCUS EEG Amplifier Review

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In my May 2007 review of the 4-channel Excalibur, I was very impressed with the signal processing of this amplifier made by QDS of Argentina, but I noted some design issues. I have used my Excalibur for 8 months now, and I love its signal quality and responsiveness. In November QDS released a redesigned 2-channel EEG amp called the FOCUS. The demand has been so great that it's taken this long for me to get one to test for a review. It was worth the wait!

The FOCUS is 3X4¾ inches (8X12cm) and stands less than 2 inches (5cm) tall. Its black hard plastic case, electrode plugs, on/off rocker switch and LED's for Power and Low Battery are all high-quality and well marked. On the back are a serial port and a plug for the 9-volt battery cable.

Pulling loose the wiring when changing 9-volt batteries is a common problem. The FOCUS uses an 8-inch (20cm) freestanding wire that plugs the battery into the unit. If you manage to pull the connector loose (and this is the strongest 9-volt battery connector I've ever used), you just replace the wire.

Most users will need to buy a Serial/USB adaptor to plug into a USB port. The FOCUS is 50% faster than the previous fastest amplifier in BioExplorer. You'll want a HighSpeed (around 1 Mbps) adaptor, preferably with a buffer. These range in price from about $12 to around $40. If you get a slow adaptor, you'll get "sync errors", because the amplifier is trying to push a watermelon through a straw!

You'll also want a smart 9-volt battery charger with a couple 9-volt NiMH rechargeable batteries. FOCUS' low battery light goes on when signal quality could start to deteriorate. You Pause, change the battery and hit Play again. The battery I tested with my FOCUS lasted for 3 hours without a break.

I compared the FOCUS and Pendant EEG, because they are alone on a price rung that is 25-35% the cost of an Atlantis or Infiniti, with specs that generally equal those devices. Both work with BioExplorer or BioEra. FOCUS is a 16-bit amplifier to the Pendant's 12 bits. Pendant sends data to the computer at 1280 bits per second (bps) and 38400 baud. The FOCUS sends 5120 bps and 57600 baud.

Most amps include built-in filters to block signals below and above certain frequencies. Any filter slows the signal, and these "hardware" filters affect training signal as well as display. Like the PET and QPET, QDS leaves out these filters. You can add filters to the software to block the same bands, but they are only used in front of the spectrum analyzer and oscilloscope displays, so they don't slow the signal being trained. If you choose not to use these filters, you will never need an impedance meter. You will immediately know if you have a bad connection or electromagnetic noise in the environment. Without these filters, FOCUS can read signals from 0 to 128Hz. You can do very low frequency or even Slow Cortical Potential training. To inhibit EMG (muscle tension), you could set a filter from 70-120 Hz.

The FOCUS is well-made of top-quality components, yet at $570, it's one of the least expensive units available. Is it possible that QDS has managed to upgrade the package, lower the price AND maintain signal quality? To test this, I compared an EEG Pendant and a FOCUS on the same computer, same USB port and same BioExplorer design. I shorted together the electrode plugs to block outside noise and see what signal was coming from inside the amplifier itself.

The Pendant (top image), like most amps, shows about ½ microvolt (uV) of noise even when nothing is coming into the amplifier. That signal is beneath whatever EEG is being read from the brain. Then I looked at the FOCUS signal for the same hookup, but I magnified it 1000 times, looking at nanovolts (billionths of a volt) instead of microvolts (millionths of a volt). Sstill no noise at all!

The FOCUS also does not use what are called High Input Impedance Pre Amplifiers which are very common in today's amplifiers. Because it has no internal noise to hide, the FOCUS doesn't need to filter it out of the signal. The result seems to be a more responsive signal, since literally none of the subtleties of the EEG are being blocked by this screen.

Any piece of equipment is only as good as its support. The Pendant and the FOCUS are both one-person shows. Anyone who's ever had to wait days or weeks with clients in the pipeline to get a response to a technical question or a repair knows how frustrating that can be.

QDS has been among the most responsive companies we've worked with. Dr. Rocatti corresponds with any buyer who wishes to improve the quality of signals or resolve potential issues with the hardware. After troubleshooting online, he has sent new amplifiers when there was a problem rather than waiting to receive the one that is not working. He is developing a "loaner" system with Brain-Trainer, so we can ship a working unit immediately (without going through customs) when repairs are indicated.

Whether you are a professional or a lay user, you can get an excellent combination of amplifier and software for about $1,000. Training amplitude, coherence, synchrony, symmetry, variance, peak frequency, even entropy and more complex options can all be done with this system. With the astonishing technical characteristics of the FOCUS, it's hard to imagine a good reason for spending more.

If you are not receiving this in your mailbox, you probably won't have the two images of comparative signal quality (they are stripped by Yahoo before the message is stored). These can be found at http://health.groups.yahoo.com/group/braintrainer/files/ProductReports/ in the review on Focus.

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