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kagliostro
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« on: March 09, 2012, 04:06:58 pm » |
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Looking around I've find this drastic solution for shielded heaters
Kagliostro
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« Last Edit: March 10, 2012, 05:37:30 am by kagliostro »
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John
So what's that do?
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Posts: 852
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« Reply #1 on: March 09, 2012, 04:09:29 pm » |
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 And you all called me crazy! Well thar's two us crazy 'uns out dere!
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Tapping into the inner tube.
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HotBluePlates
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« Reply #2 on: March 10, 2012, 05:38:25 am » |
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Well, I guess one can do that.
There is, however, cable available with 18ga twisted pair, with an outer shield.
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From Principles of Electron Tubes: "... the phase of the output voltage is retarded."
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kagliostro
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« Reply #3 on: March 10, 2012, 10:38:46 am » |
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I agree that is an extreme solution
however iron is the better material for shields (excluding mumetal)
Kagliostro
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drgonzonm
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« Reply #4 on: March 10, 2012, 01:58:43 pm » |
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Why not SS air lines with flaring at ends. Extreme sports, now Extreme Amp solutions.
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birt
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I love tube amps
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« Reply #5 on: March 11, 2012, 04:32:39 am » |
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if you want to go that far it's much nicer to drill through the chassis and run the heaters on the outside.
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Fresh_Start
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« Reply #6 on: April 24, 2012, 03:57:46 pm » |
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Seems like I saw copper tubing at a hobby store not too long ago and was thinking it might make a decent shield for the first 1 or 2 stages of a preamp. The problem I had was figuring out how to attach it permanently to the chassis.
In most amps, you don't really need 18 gauge heater wires except for the power tubes. 12AT7s or preamp pentodes draw a lot more current than 12AX7s though. Where I'm headed is that shielded 22 gauge, twisted pair wire costs a LOT less than 18 gauge.
Cheers,
Chip
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We have proven once again no plan survives contact with the enemy, or in this case, with the amp. Plan to be wrong about something. |
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drgonzonm
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« Reply #7 on: April 24, 2012, 06:44:24 pm » |
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attaching copper tubes.
use some power cord clamps, and a ground wire.
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mresistor
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lost in the ozone again
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« Reply #8 on: May 11, 2012, 06:19:15 pm » |
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attaching copper tubes.
use some power cord clamps, and a ground wire.
or maybe braze it or solder it directly to the chassis...... |
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WPLJ
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proaudioguy
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« Reply #9 on: August 03, 2012, 10:19:55 am » |
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I would think tightly twisting the heater wires together and moving them as far away from the circuit would be as good as any shield other than mu. It's probably important that the twists are tight and the current is balanced. Seems the 60Hz radiation would cancel out within a short distance. Has anyone done any tests to check the effect of the shields? Even a 6dB reduction all else being equal might make it worth doing on a recording amp. Not much point in a combo amp I suspect.
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stratele52
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« Reply #10 on: August 25, 2012, 03:25:18 am » |
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+1 proaudioguy
A "standard" heater wiring ,if well done, is as much quiet as any other method ; DC and shielded wire. I test both.
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