Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Diverted on October 25, 2019, 08:09:06 am
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I went off on a tangent yesterday and started stuffing electrolytics into a fun build I'm doing as a favor to a friend of mine (he's buying parts and beer). He wanted a stripped down, single channel Twin Reverb with tremolo deleted. Wants it in a Princeton-sized cabinet with a single 12.
Anyway, the electrolytics won't fit in a doghouse on top of the chassis, and the circuit board takes up most of the lateral space right of the transformer. So in the pic shown, I put the first two stages of filtering (two 100s in series and two 68s in series) to the left of the transformer, and the C (two 39s in series) node and D node (single 20uf, 500V) above it.
Am I going to run into issues with noise or heat with this layout? The filter choke snakes around the power transformer, the spacings are pretty tight etc. I'm not married to this, and can always pull it out and try something different.
I have read here about Doug Hoffman's method of running the caps, or most of them, along the top of the board. Would that be preferable?
Or am I alright? My main concerns are dependability and low noise.
Thank you!
Other notes: The output transformer is all the way at the other side of the chassis, with wires snaked across top, coming out through the hole at bottom left where the choke wires are.
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Was not happy at all with the layout in the post above, so gutted it and started over. It just seemed like too much of a Rube Goldberg configuration.
I have a question about the above the circuit board style of electrolytic wiring that Doug Hoffman sometimes uses. The B, C and D nodes are all going to be above the board. Will the B node's placement so far away from the rest of the filter caps cause issues? I will tie the grounds for B and C nodes into the lug at bottom right of the power transformer; the D node will be tied into the preamp ground bus.
Thank you for any input on my grounding scheme or layout as I've never wired electrolytics this way before.
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the D node will be tied into the preamp ground bus.
as long as B doesn't wander aimlessly over, around n under the above ground scheme you should be good
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I would be tempted to use a JJ 40/20/20/20 500vdc cap can and mount it between the PT and the circuit board as long as the choke is not mounted there.
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I would be tempted to use a JJ 40/20/20/20 500vdc cap can and mount it between the PT and the circuit board as long as the choke is not mounted there.
I was thinking about that but original b, c and d caps are soec’d At 525vdc. B node will see 450; don’t know if I want to stress them with startup surge?
Thanks👍
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the D node will be tied into the preamp ground bus.
as long as B doesn't wander aimlessly over, around n under the above ground scheme you should be good
It should be a pretty straight shot and I'll keep it as clean as I can. Thank you!
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CE Manufacturing makes a 40/20/20/20 525vdc cap can twist lock style you will need to buy the mounting plate also. More $$$.
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Try to locate your caps close to the stages they supply instead of all in one place like Fender does it. It makes for a better grounding scheme with better control of your grounding, and shorter wires going to the stages they supply.
Greg
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Try to locate your caps close to the stages they supply instead of all in one place like Fender does it. It makes for a better grounding scheme with better control of your grounding, and shorter wires going to the stages they supply.
Greg
I agree with this. One advantage of Doug's method is you can run the negative side of all cathode caps that are supplied by that ecap to the negative side of the ecap with short wire runs. I have had good luck reducing noise levels by using this method. Whether another method would work just as well I don't know. When I have used can caps with multiple positive tabs and one negative tab I try to mount it close to the area where it will be used for the same reason.