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mach1 28th April 2009 05:31 AM

Glow tubes as series regs ?
Has anyone used glow tubes as SERIES regulators / filters? I ask because DECWARE are apparently using this topology in their Mini Torii amp (see extract from design notes below).


‘In both instances, where the grids of the output tubes and the input stage are regulated, they are not regulated in the typical way. Instead the regulator tube is wired in series with the load. The tube creates a voltage drop and acts as a filter that seems to block much of the nasty harmonics and noise that seeps in from your AC power. Rather than resistors or chokes which provide a direct conductor for the high voltage, the regulator tube creates a condition where all the high voltage must jump between the cathode and plate through a vacume, so hey folks, look no wires! It simply amazes me what doesn't make the jump. In fact even ripple rejection is many times higher that it would be with the equivalent voltage dropping resistors. Off all the tube amplifiers available on the market today, very few use tube voltage regulation so it's realistic to think this amp will be somewhere in the top of pack sonically. NOTE: If you wire the regulator tubes the normal way as a shunt to ground, they actually inject noise that must be later removed.’
Comments ?

wrenchone 28th April 2009 05:49 AM

Sounds like doody to me - the regulator tube will represent a complex nonlinear impedance, but I cannot imagine it suppressing noise any better than a plain resistor, indeed, it may inject junk of its own. Do you have any insight as to the exact circuit where this is used? Not that it would make me much less skeptical, but it would help to see how Decware has things strung together. BTW, the usual VR tube has a gas fill, not a vacuum....

On the other hand, if they are using normal tubes as series regulators, they can expect to strain some crap out - a lot will depend on what kind of tube is used.

Colt45 28th April 2009 06:21 AM

Assuming they are talking about glow tubes, and not some pass reg, it's completely ********.

Makofoed-6sn7 28th April 2009 08:44 AM

Hi There,

Here is another example:

It has worked great for many years in that circuit, but it might be important to add that the leslie amplifier plus speaker cabinet is a pretty special specimen. So if the glowreg. add som non-linearity it's a part of the systems "sound". Last time I mesured an leslie amp it was only flat from around 50hz-10k...

Best regards,

Magnus K.

revintage 28th April 2009 09:19 AM

A series connected glow tube does not regulate, it only drops voltage.

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