The AVA Vision RIAA Phono Preamplifier
The Vision Phono Preamplifier is a brand new direct coupled split passive EQ
very high performance solid-state phono preamp with high current buffered output circuits to handle long cables, complex tape loops, and other difficult loads.
It is based on reaching way back into our archives, back to the Jensens Stereo Shop days of the 1970s, to revisit a schematic I drew then. The original never saw production because the integrated circuits of those days just were not quiet or linear enough. In addition, trying to null DC offset took trimming resistors for each IC and that would have been a nightmare in production.
However, there was lots of promise in that old circuit so I examined it again recently and we bread-boarded it up once more, but this time with much better modern ICs and more.
Rethinking the design further, I realized we did not need the third amplification stage, just a much better choice, an outstanding current buffer to isolate the second passive EQ section from the real world. Then we spent weeks testing and listening to almost all the modern linear ICs available, some even surface mount chip types. We finalized the design with National LME49710 front end ICs and the very expensive Burr-Brown OPA627 ICs for the second stage. This combination provides the low noise and grain free outstanding dynamic range we demand. We never considered dual ICs because of their higher crosstalk and distortion issues.
Because the integrated circuits we selected have very low DC offset or drift, all coupling capacitors have been eliminated from the signal path. The Vision Phono Preamplifier is direct coupled from input to output. Because the linear ICs are driven to unity gain at DC, you have no worries about which brand or type of coupling capacitors to use, there are none. The two capacitors in the passive EQ sections are select polypropylene types. There is plenty of raw power supply built into the Vision board itself, along with careful supply decoupling directly at each active device power supply rail feed.
In our 17 inch wide chassis, the power transformer and high current plus and minus 15 volt regulated power supply board can be kept far from the active circuits to reduce noise even more.
In addition to the free standing Vision Phono Preamp, the new Vision Phono Preamp is available right now as an option that can be built into all new AVA preamplifiers.
It is also available as an outstanding upgrade to the phono sections of almost any older AVA preamplifier.
If you own a preamplifier without a phono section and now you wish you could have great RIAA phono performance without starting over again or spending a fortune, we have just what you need, an Audio By Van Alstine RIAA Phono Preamp. Or consider replacing the harsh and lumpy phono section of your present receiver or preamp with one of these musical gems.
The AVA Vision RIAA phono preamp is suitable for any normal output phono cartridge, head amp, or moving coil step-up transformer. It comes packaged in our rock solid 17" wide x 12" deep x 3.5" high chassis. It has gold plated phono inputs, gold plated line outputs, and a lighted power switch. Connect the Vision Phono Preamp to your line preamp or receiver and enjoy records all over again.
Call me for more details. It is available right now. 651-330-9871
Frank Van Alstine