power supply filtering design

[surfsup]

I am wondering if it is better to put all the caps in one corner of the chassis and then run long leads for B2, B3, B4, B5...

or...run a lead from cap to cap, with the rail cap near the tube it is supplying. The filtered lead would be shorter in this latter case.

What is the consensus here on this?

[philo43]

I usually locate the caps together near the PT for convenience with the exception of the 1st preamp supply cap that I locate near the #1 preamp tube since this is where any stray AC that might be picked up by the longer lead will cause the biggest problem.

[JamesHealey]

in practice many do not put the filter cap next to the node it's filtering with a high success rate.


although filtering right up to the node with the filter can right next to the node is definitely the best way as it filters better and you can keep the current for that stage grounded in one area using a star ground design.

[surfsup]

I was thinking something like this for the XitsX10Clone, I am challenging myself with the gargantuan Solen 15uF 630s! The power tubes will prob be moved over closer to B1/B2 but the main question is if anyone sees anything critically wrong here with this layout having the Solens near their respective tube(s)...? The proposed ground scheme in green (two star grounds, one at input and one at P tranny)

[img737]http://chicagocadcam.com/ChrisHahn/schem/X10Layout.jpg[/img]

[Lonely Raven]

I was thinking something like this for the XitsX10Clone, I am challenging myself with the gargantuan Solen 15uF 630s! The power tubes will prob be moved over closer to B1/B2 but the main question is if anyone sees anything critically wrong here with this layout having the Solens near their respective tube(s)...?

[img737]http://chicagocadcam.com/ChrisHahn/schem/X10Layout.jpg[/img]

I am *so* building one of those once the forum gets all the details worked out.

I need a good layout though...I'm no good at figuring out how to turn a schematic into a good layout.

[leadfootdriver]

Looks cool! Where would you source a chassis like that?

[M Fowler]

www.Turretboards.com inward mounting ears chassis in 17.5 x 6.5 x 2.5 would work well or even smaller if you want.

www.rjguitars.net also has some chassis. 14.5 x 7.5 x 2

Mark

[leadfootdriver]

NICE!

I think I wanna do an Express'ish build for my next project.

One of those blanks from RJG are the ticket.

[Cliff Schecht]

Capacitors are only effective up to a certain point, at which point their impedance increases dramatically and they stop acting like caps. Adding long leads to the bypass caps makes them less effective by increasing the impedance earlier. Yes you can get away with long leads on some amps but in higher gain stuff, you will find that it's noisier with the caps further away if not downright unusable (long leads can also cause stability issues).

[leadfootdriver]

What in your opinion is the optimum value of filtering per triode? I like KEN's layout of having a separate cap for each stage.

Doesn't this help decouple the stages and improve stability in high gain designs?

[Cliff Schecht]

Having a cap on every stage helps different stages not interact when one pulls a bunch of current. This is not necessary though, and in a lot of cases isn't practical. The ideology that I now follow is to decouple ever pair of inverting stages as two inverting stages cascaded tend to cancel out hum. If I have a cathode follower after two inverting gain stages, I'll just tack it in with the other two guys without issue.

Optimum value? That depends on what you want from your decoupling caps! It really doesn't have an effect on the preamp when you go too high, it only really affects things when you go too low.

[azatplayer]

The filter size will affect the frequency of that node, as will the size of the dropper to it. The dropper/filter relationship have more going on than feel and gain, higher dropper, more gain tones and brighter, higher filtering more bass.
So challenging sometimes to get the right mix of bass/treble response and feel and gain mixed just right. Usually i end up close to whats been done before, tho sometimes your component choice leads you to adjust accordingly.
I hear the solens are super fast, will make them brighter, that may have you adjusting somewhere else to get the bass response where you want it.

[rsi]

What did you use to draw that layout? It looks good!

[surfsup]

Rsi, a CAD/CAM software for machining, it has some design capabilities but it isnt sold as a design software. It costs several thousand so stick with what you've got. I just happen to have access to this and nothing else. Personally i like the colored layouts some people post.