Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: allstonma on November 05, 2021, 07:07:17 pm
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Hey All
Building a kind of 1484 smash mix for a friend of mine. Unfortunately the schematic doesnt show voltages for the last two points on the power rail. Can anyone tell me what I should be seeing at r58 and r59 ?
Thanks
TH
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1) Does it even matter? Voltages from 150V to 350V may work fine.
2) Voltages are given for key points in the V1 V2 V3 stages. A hasty add-up says the tops of R7 R8 (bottom as drawn) are 180.6V.
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1) Does it even matter? Voltages from 150V to 350V may work fine.
100% right
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1) Does it even matter? Voltages from 150V to 350V may work fine.
2) Voltages are given for key points in the V1 V2 V3 stages. A hasty add-up says the tops of R7 R8 (bottom as drawn) are 180.6V.
1) I think so, part of that amps sound will be dictated by the operating voltage of the tubes in the first two stages (along with many other things of course).
2) What value did you use for amps (I) in calculating this ?
Many Thanks !
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dictated by the operating voltage of the tubes in the first two stages
Ohm's law and tube type work together "creating" the "tone"
I've found it is WAY easier to make a good working amp 1st. Using stages from already designed amps to "get you close"
then tweak (change out values) to hone in on "your tone". Math has never helped with this stage, Math works well to get a good solid working amp 1st
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I've found it is WAY easier to make a good working amp 1st. Using stages from already designed amps to "get you close"
Yes that is what I'm trying to do starting with the Silvertone 1484.
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my last build was my-take on a 1482 Silvertone, nice practice amp although it's being used as an audio amp currently :icon_biggrin:
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Your big challenge will be getting from 480V at the first node down to 340V at the second node. Once you have 340V at the second node just use the 68K as shown and the voltages at the last two nodes will be correct. Then you can measure them and tell us what they are.
There are some 1484 owners on this forum. Maybe someone will measure those voltages in their amp. I would think that a little google time will turn up some answers. Just don't search for Slivertone 1484! :wink:
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Voltages are right here...
https://el34world.com/Forum/index.php?topic=24915.msg269319#msg269319
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Your big challenge will be getting from 480V at the first node down to 340V at the second node. ...
Note that the amp power is a stack of voltage doublers. There is 480V at the top of the stack but they took 360V from partway down. A choke, say 1k and 20mA, leaves 340V. And as you say from there.
A clever way to get a *solid* ~~350V for screens. And not need a bunch of 500V caps for all nodes at cold-start. But 5k or 10k 5W (buy a fistful of 2k 2W and try 3, 4, 5 in series) might work as well at 480V in.