Tube CAD Journal: E-mail

diminished battery life. Using the existing circuit with capacitor coupled output transformer might be a good idea, as even a winding ratio of 2:1 would double the peak current into 32 ohms.

Conclusion

I wish there were a conclusion. But until more information on available output transformers comes our way and until further tests are preformed, no conclusion can be reached. One test that must be done is a shootout with a reality check Op-Amp based headphone amplifier. If the tube amplifier does not handily beat this $5 contender, we are wasting our time. By the way, always have a reality check handy. When comparing $400 patch cables, throw in a pair of $5 Radio Shack specials. When comparing $4000 8 watt amplifiers, throw in a Dynaco ST-35.

Is this a promise for yet another article on tube headphone amplifiers? Eventually, yes.

//JRB

E-Mail from where?

The rule has been to omit last names and e-mail addresses unless the writer had clearly expressed for their inclusion. This rule will continue. However, a few readers have asked that all e-mails include the country of the sender. I like this idea and hope to see these inclusions. So please where are you from?

Subject: Circuit Help

I have been experimenting with amps to drive the bottom end of my system ( yes the OTL that haunts these pages drives the top) and have built the single ended tube/MOSFET as shown on

http://digilander.iol.it/essentialaudio/hybrid.

I found, as with many other trial setups using transistors to augment tube circuitry, that the sonic signature of the silicon overpowers the tube and that any technical advantage that may be gained is swamped by the transistor's artifacts. The design mentioned above has many features to recommend it and, as you mentioned last month the use of current mirror technology in tube circuits, I now wonder about what modifications are required to convert the solid-state current mirror to a tube based one.

I have never seen a tube "current mirror" used in a differential tube amp but they are "state of the art" in transistor land and do wondrous things to linearize those circuits, reducing distortion and increasing slew capability.