Raise Bias voltage, leaving step up same?

[john65b]

Hey guys,

Would it be beneficial to raise bias voltage while keeping stator voltage the same?

I have a Shackaman Direct Drive PCB (over 200hz) that the Bias voltage is right around 1.8KV, and the plates of the EL84 stacked tubes driving the stators are 1/2 bias voltage or 900V.

I could just use a conventional Bias supply to supply higher than 1.8KV Bias voltage, or add another cap/diode to the existing ladder multiplier and get 3600v.

In a simpler question, on a DD amp, does the Stator voltage have to be around 1/2 of Bias voltage? Any benefit to SPL, frequency response, etc having higher bias voltage than just double of stator voltage?

Sorry if a lame question...

 

[chinsettawong]

If you can use a higher bias voltage, you will get higher efficiency out of your ESL.

 

[john65b]

I said "Step Up" on the title, but I meant Stator Voltage from a Direct Drive Tube Amp. I guess it would not matter?

 

[tyu]

In a simpler question, on a DD amp, does the Stator voltage have to be around 1/2 of Bias voltage? Any benefit to SPL, frequency response, etc having higher bias voltage than just double of stator voltage?


add another cap/diode to the existing ladder multiplier and get 3600v. ....this looks eze to me....i would add the diode............


Sorry if a lame question.....
John
there are No lame questions....
only lame Answer...........

 

[john65b]

Tyu - thanks buddy...

I only ask since looking at the two DD amps schematics I have seen, the Acoustat servo amp has 5KV bias, and 5KV plate voltages at both stators...and the Shackmans have 1.8KV bias and 900V on plates to both stators...

I will try and see what I get...

 

[moray james]

John: tyu's advice is good, one more multiplication section of voltage is what you need. I would not recommend that you go any higher than that. Reason is your panels are old and ESL's generate very small amounts of ozone when they play so over the decades of which most Acoustat's are times 3 by now the dielectric on the stator wires is getting broken down compared to when it was new. The insulation is now kind of sponge like on a molecular level and if you apply more than one more step of voltage you will find your panels may arc on loud dynamic peaks. Voltage can more easily punch through the dielectric. One more stage over what you have now will make for a very nice improvement. Best regards Moray James.

 

[tyu]

Thanks Moray.............happy hoho