Just For Fun Ppa Specs

Just for fun, useless PPA specs

I have a v1 PPA that I decided to test at work today with a scope. 627/637 opamps, 4x buffers, 10 gain, 24 volts input from an Agilent bench supply. Source was an HP function generator. The frequency response is dead flat (well +- 1mV was as accurate as I looked) from about 0.1Hz to 1.5MHz with Sony MDR-570s (32 ohms) attached. the -6dB point is roughly 5.8MHz. The test was roughly the same with Sennheiser 590s (150 ohms), though I didn't examine the low end. Tests with square waves show that it really does a good job of producing real square waves. On 40Hz square waves it had a 300ns rise time, where rise time is defined as the time it takes to go from the lowest state, all the way to the high state and settle. That's about 33MHz. The actual primary rise was like 100ns, there was just a little overshoot that took a second to correct. The output signal was in the realm of 300mV p-p. No distortion figures or the like, the scope really isn't suited for it, and I don't know how to work the network analyzers. Maybe I'll get someone to help me with one some time later and post some more results. Not that it really means much, the amp is way overkill for audio, but we knew that already. In case you are wondering, it tends to pick up a little RF. There was some low level, extremely high frequency distortion present on the scope all the time. Low enough and high frequency enough I doubt it makes any difference sonically, but it is there. From this head-Fi link http://166.90.205.111/forums/showthread.php?t=180595&highlight=fun+ppa+spec s