Reducing Heater Voltage?
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Re: Reducing Heater Voltage?
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?
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?
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Re: Reducing Heater Voltage?
Tubes need to be installed to see any reduction....
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Re: Reducing Heater Voltage?
Yes, without a load, there is no voltage drop across the resistors.
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Re: Reducing Heater Voltage?
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
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
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Re: Reducing Heater Voltage?
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....
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....
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Re: Reducing Heater Voltage?
the filter caps only handle 500v anyway, so the 240v primary is the best solution.
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Super 100 amps: 1202-119 & 1202-84
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Re: Reducing Heater Voltage?
measure heater voltages with the tubes connected
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Super 100 amps: 1202-119 & 1202-84
JTM45 RS OT JTM50 JMP50 1959/2203/34/39
http://www.myspace.com/prostitutes" onclick="window.open(this.href);return false;
Super 100 amps: 1202-119 & 1202-84
JTM45 RS OT JTM50 JMP50 1959/2203/34/39
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Re: Reducing Heater Voltage?
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?
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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Re: Reducing Heater Voltage?
Hi...the power resistor method is definitely the easiest. With the KT88s drawing 1.6A and the 6N1P pulling 0.6A just make sure it is big enough!
As Eric said you could convert the heaters to DC and use a couple of smaller resistors and some caps to filter the current. However with this design DC heaters aren't at all necessary to have a hum-free amp.
As Eric said you could convert the heaters to DC and use a couple of smaller resistors and some caps to filter the current. However with this design DC heaters aren't at all necessary to have a hum-free amp.