Regarding the question of "duplex opportunity" with the TDT RP2: We haven't
done it (yet), but it should be no problem. The duplex mode is often used
for calibrating loudspeakers in our lab, but we've only done that using
TDT's older "System 2" hardware, which uses separate A/D and D/A modules
controlled by a central DSP card.
The biggest limitation of the RP2 is running out of clock cycles. Each
"device" in software takes up clock cycles. If you program an elaborate
recording/playback device (e.g., with signal conditioning, temporal
windowing, thresholding, etc) you can run out of cycles when using the
system at it's maximum sample rate (200 kHz). In our lab, we use the device
mainly to generate complex ultrasonic acoustic stimuli. If we were
recording signals simultaneously, we would surely run out of clock cycles if
we were using only a single RP2. The solution is to add more RP2's to the
setup, and split the tasks across them.
We have been able to playback very long ultrasonic signals (lasting some
minutes) with the RP2, but we had to roll through a double-buffered memory
structure and use their high-speed USB interface to do it without
interuptions.
Regarding dynamic loudspeakers, we've had good luck with leaf tweeters
(e.g., Panasonic EAS 200). They were hard to come by, heavy, and don't
tolerate overdriving at all. But they have excellent and broad frequency
response (1 - 100 kHz) and a reasonably brief impulse response, and don't
require DC bias like electrostatic speakers.
*************************************
William E. O'Neill, Ph.D.
Bat Auditory Research Lab
Dept. of Neurobiology & Anatomy
Univ. of Rochester Sch. of Med. and Dent.
Rochester, NY 14642-8603 USA
Phone: (585) 275-4023
FAX: (585) 756-5334
> -----Original Message-----
> From: Eckard Blumschein
> [<a href="[EMAIL PROTECTED]" rel="nofollow">[EMAIL
> PROTECTED]</a>]
> Sent: Friday, February 14, 2003 4:25 AM
> To: ONeill, William; [EMAIL PROTECTED]
> Subject: RE: Ultrasound playback setup
>
>
> It is not obvious to me that TDT offers the duplex
> opportunity, that is,
> sending and recording at a time as do pretty cheap sound cards. Also,
> manufacturers rarely show the step response of their systems.
> Nonetheless,
> I am sure electrostatic speakers are the best option in that
> respect. I
> wonder if anybody can recommend any active electrodynamic
> speaker to be
> used together with a duplex sound card. I am unhappy with a lot of
> unacceptably oscillating step responses.
>
> Eckard Blumschein
> <a href="http://home.arcor.de/eckard.blumschein";
> rel="nofollow">http://home.arcor.de/eckard.blumschein</a>
>
>
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