Home Tube DIY Asylum

Do It Yourself (DIY) paradise for tube and SET project builders.

[ Follow Ups ] Thread: [ Display  All  Email ] [ Tube DIY Asylum ]
[ Alert Moderator ]

I would guess it won't bee the "COMPACT" ...

I built this amp (original compact as on Neds site) over a year ago to resolve whether or not it was really a super elegant implementation of a single ended design using a more commonly available PP OPT. The "speculation" was that the undriven 6BQ5 was actually a current source designed to null out the DC from the driven 6BQ5 thus resulting in zero net flux in the OPT under idle conditions.

Testing indicates that the output stage is nothing more than a phase inverter capable of delivering power. It is very poorly balanced WRT drive on each phase due in large part to the relatively miniscule "tail". Power output is also a bit low by 6BQ5 standards at about 7W @ 1KHz with very obvious clipping...this using a regulated PS for optimum measured performance. THD was not measured but I expect it to be high for a PP design because the "undriven" 6BQ5 operates at about 50% of the drive of the "driven" 6BQ5. One interesting improvement should be replacement of the common cathode resistor with a CCS but I never got around to trying it this way.

The amp sounded just OK but after a few weeks was dismantled because I needed the OPT for another project.

Overall, I don't believe this amp will satisfy the discriminating listener over the long term. However, it's simple and low enough cost that nothing is lost if one wants to try it. IOW, YMMV.

This post is made possible by the generous support of people like you and our sponsors:
  Amplified Parts  

Follow Ups Full Thread
Follow Ups
You can not post to an archived thread.

[ Top Top of Page ] [ Contact Us ] [ Support/Wish List ] [ Copyright © 2024, Audio Asylum, all rights reserved ]
[ General ] [ Speakers ] [ Tubes ] [ Vinyl ] [ Digital ] [ Hi-Rez ] [ Video Asylum ] [ Cables ] [ Tweaks/DIY ] [ Music ] [ Films ]