Reducing Heater Voltage?

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revolver1
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Reducing Heater Voltage?

Post by revolver1 » Wed Oct 24, 2018 1:57 pm

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revolver1
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Re: Reducing Heater Voltage?

Post by revolver1 » Wed Oct 24, 2018 2:13 pm

So I've powered it up hooked up to the 220v tap with a wall voltage of 230v and I'm getting 525Vdc out of the rectifier.

Across the heaters I'm getting 7.23Vac and 3.61Vac on either side. I did some rough calcs and rounded up a bit I went for .3 Ohms on either side of the heater wires to try get down to 6.3Vac. (Now doubting my calcs).

So I got two .14 and two .16 Ohm resistors and soldered two together in series aiming for a total of .3 Ohm I measured each set and they both came in at .6 Ohms, I then gator clipped them in to see what I'd get and to my suprise It does absolutely nothing, nada still got the same voltages.

So then I soldered together 5 resistors and clipped them in on each side and I't did a bit but not alot. I have now ordered some larger 3Watt resistors 1 Ohm and up, I'm just not sure I'm doing the right thing?

revolver1
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Re: Reducing Heater Voltage?

Post by revolver1 » Mon Oct 29, 2018 4:31 am

Tubes need to be installed to see any reduction....

danman
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Re: Reducing Heater Voltage?

Post by danman » Tue Oct 30, 2018 7:35 pm

Yes, without a load, there is no voltage drop across the resistors.

RockinRocket
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Re: Reducing Heater Voltage?

Post by RockinRocket » Tue Oct 30, 2018 11:02 pm

You said in another post your were looking for head room?

I don't know if dumping more voltage in to a lowervolt tap is the way to go.. I would assume less life from the power transformer could be expected. May last a life time though :what: :what:

revolver1
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Re: Reducing Heater Voltage?

Post by revolver1 » Wed Oct 31, 2018 3:42 am

I was going for a West Coast modded amp but in the 50w format. I've posted a little bit in the 6550 Experience post in the Hendrix section but now it's wrapped up I need to finnish off the build journel I started a year ago in the 50w section.

I needed high plate voltage so I went for the Classic Tone but i over looked the fact it only has 220v or 240v primary taps and I'm on 230v.

As it turns out I wired to the 240v tap, the heater voltage is about right and i have 460v to 466v on the plates. Its one hot PT....

Roe
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Re: Reducing Heater Voltage?

Post by Roe » Wed Oct 31, 2018 7:30 am

the filter caps only handle 500v anyway, so the 240v primary is the best solution.
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Re: Reducing Heater Voltage?

Post by Roe » Wed Oct 31, 2018 7:33 am

measure heater voltages with the tubes connected
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awangotango
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Re: Reducing Heater Voltage?

Post by awangotango » Fri Apr 12, 2019 7:58 pm

if all else fails, variac it down 10%. but I seem to recall a method to strictly attack/adjust heater voltage,....

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Re: Reducing Heater Voltage?

Post by bhyatt1 » Wed Nov 13, 2019 5:32 am

I had an issue with high heater voltages on my bassman and was advised to use 2x120-150mOhm resistors on the heater wires to drop the voltage. Worked out great.

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