Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: terminalgs on August 13, 2018, 11:49:02 am

Title: SS oscillator for harmonic vibrato
Post by: terminalgs on August 13, 2018, 11:49:02 am



Any thoughts on what would be required to make the oscillator and phase splitter in a 6G5-A harmonic vibrato be SS driven?  Do I just need to concern myself with the amplitude of the oscillation coming out of phase splitter ?   


Will those .1 caps to ground act the same upon the oscillation sine wave regardless of the source impedance of transistors vs. tubes?


(https://i.imgur.com/wwruDxA.jpg)


I have a PT that I'd like to use but it doesn't have enough filament amps to cover all the 12AX7s needed..


I figure I might start with the oscillator below @ Q304 to drive a phase splitter like the ones at Q301 and Q302.  maybe put an emitter follower between the oscillator and the split like fender did, or add a gain stage to the oscillator output to get the osc. amplitude to match what a tube version would create.


(https://i.imgur.com/AQlnunT.png)


dunno if this post belongs here or in the SS room
Title: Re: SS oscillator for harmonic vibrato
Post by: jjasilli on August 13, 2018, 11:53:54 am
Checkout: http://geofex.com/ (http://geofex.com/) > scroll to: 02/05/02   MOSFET Heresies Again! Make a solid state analog of the Fender tremolo circuit for adding tremolo to an non-tremo amp, or free up a tube for more audio gain
Title: Re: SS oscillator for harmonic vibrato
Post by: PRR on August 13, 2018, 08:33:22 pm
In general I would just stick a transistor in (but I know voltage and impedance).

In THIS case.... that's a pretty complicated tricky circuit, and may have subtleties which are not obvious. _I_ would add a filament transformer and stick with exactly what Leo did.