Stand out phono stages

Ralph (Atmasphere) wrote:

>All preamps are class A.

For discrete circuits, this is true. OTOH, the vast majority of opamps only have a very small output range in which they run in class A. If the signal amplitude exceeds that range, the opamp's output circuits will shift to class AB operation. This is because opamp manufacturers place great emphasis on energy efficiency, and therefore internally bias their output stages in a manner that keeps the standing currents quite small.

That said, it is possible to keep many opamps in Class A operation over a larger range by connecting a current source (or even a well-chosen resistor) from the opamp output to one of the power rails (which rail works better depends on the design of the individual opamp). However, this "forced" Class A operation needs to be implemented by the preamp designer. I have seen many opamp-based preamp designs (and DACs) where Class A operation was not implemented.

kind regards, jonathan

The new stage by Clearaudio may well be a game changer - amplification in the headshell before going down the arm - has anyone heard one yet?

Hi Lohanimal: The old Yamaha HA-2 (1979) and HA-3 (1982) were also of this type.

http://jp.yamaha.com/products/audio-visual/special/hifi-history/other/

The HA-2 shipped with a dedicated headshell with two embedded JFETs, thereby bringing the front end of the phono stage forward so that it was less than an inch away from the cartridge. No modifications to the tonearm were required; the tonearm wiring could be used as-is.

http://audio-heritage.jp/YAMAHA/etc/ha-3.html

The HA-3 exchanged the dedicated headshell for a compact encapsulated block that contained two JFETs, had 4 short leads coming in and four short leads going out, and was secured with double-sided adhesive tape. The user could thereby install the JFET block into his favorite tonearm or headshell. Again, no tonearm modifications were necessary.

http://www7.ocn.ne.jp/~mai-k/analogue/transe1/yamaha.html

In more recent years, the prolific Japanese DIY amplifier designer Akihito Kaneta (Kaneda) has published at least one phono amplifier design which installs a JFET headamp inside the tonearm headshell.

kind regards, jonathan

Would it be a mistake for me to sell my EAR 834P for the ALLNIC H1201?

Everything that is old is new again, haven't seen the Yamaha's before.