Ground bus; copper bar with DIY eyelet holes?

[mike_mccue]

Hi, I just finished this assembling this amp. It is based on the AX84 PX1eXtreme design.

I used a bare 18AWG solid copper ground buss, but it is sort of daisy chained from eyelet to eyelet.

It seems like it might have been better to have used a piece of solid core along the ground bus and wrap the connections around it... but I was anticipating having to swap out some parts... and still may.

I am thinking of ways to make the assembly of the ground bus cleaner and maybe even faster in future builds. I have found that I can get a 1/4"x1/4"x12+" copper bar stock from Mcmaster Carr. (I can get a 1/2" x 1/8/"x12+" as well). I have a nice drill floor standing drill press and jig table... drilling small holes in the copper bus bar seems easy... I am ordering a piece and will try to drill and solder to it.

I think I'd like to try to use it as a substitute for the line of eyelets and small lengths of copper wire that I used here:



What do you think? Is that a crazy idea? Is it an old idea?

I have seen lots of hi current bus bars for making custom power boxes... but nothing small for audio amps.

best regards,
mike

[R.G.]

I used a bare 18AWG solid copper ground buss, but it is sort of daisy chained from eyelet to eyelet.

Neato idea!! Have copper run directly from eyelet to eyelet on the insulating board you mount your parts on! Clever... er, wait a minute! Isn't that what led the electronics industry down the slippery slope to PCBs and damnation?

I am thinking of ways to make the assembly of the ground bus cleaner and maybe even faster in future builds. I have found that I can get a 1/4"x1/4"x12+" copper bar stock from Mcmaster Carr. (I can get a 1/2" x 1/8/"x12+" as well). I have a nice drill floor standing drill press and jig table... drilling small holes in the copper bus bar seems easy... I am ordering a piece and will try to drill and solder to it.

1/4" by 1/4" solid copper rod will probably require a propane torch to solder to. Copper conducts heat away like mad. That's why holes on copper ground planes on PCBs have those little cut-away part-circles around them - it's a thermal break so you can get enough heat into the pad to solder it without the thin (0.028" maybe) copper clad taking so much heat away that those joints are cold when all the others are good. Seriously, soldering to solid copper of any substantial size needs a LOT of heat.

If I might suggest: cut yourself a 1/4" wide length of copper clad. Drill holes wherever you want them, ideally matching the eyelet holes, then just poke the wires through the holes and into the eyelets, standing up the strip of copper clad on edge. Solder both places. I'd suggest making the bottom eyelet board out of copper clad that you etch away all of except the eyelet holes and ground bus, but someone would surely have their head explode that sound that ever went through a copper clad board is forever tainted.

I think I'd like to try to use it as a substitute for the line of eyelets and small lengths of copper wire that I used here:

Very neat build!

[mike_mccue]

Thank you for the reality check RG.

:-)

best regards,
mike

[Tom Phillips]

Mike,
I like your neat construction too. I especially like that you put the filter caps near where they need to be in the circuit layout rather than all bunched together in the "power supply" section. I think that you will find that the topology of the ground system in the amp is more important to a good result than a massive ground buss. Looks like you have that nailed.
Regards,
Tom

[mike_mccue]

Thanks for sharing your thoughts Tom. The amp is remarkably quiet and the layout seems to be very well thought out.

In the spirit of giving credit where credit is due... I simply copied and made very minor modifications to the open source design published at ax84.com. This design is known as the P1eXtreme.

I think the main thing I am hoping to do is find a better way to accommodate all the ground connections without having to daisy chain the ground bus wire... but I really enjoy eyelet type connections so I was looking for an alternative to turrets and a bus wire.

I am taking RG's advice and if I do try to make a "bar" I will use a less massive piece of material.

I can't think of an effective way to cut the copper clad as he suggested... I do have a nice table saw but imagine it would delaminate the copper during the cutting procedure. Yes? No? Maybe?



best regards,
mike

[R.G.]

As Tom said, getting bypass caps out by what they bypass is a very much superior way of bypassing. And where the grounds go is more effective than how massive the copper is. That being said, the layout you have is not bad at all. The proof is in the listening. If it's remarkably quiet, even (unobtainable) perfect grounding would not add much.

A table saw would shred up copper clad. A band saw is much better, and a shear is even better for cutting thin strips. I use a hacksaw for cutting PCB material. The edges are truly ugly, but a big of sanding the edges cleans them up very well. You can just lay the sandpaper on a flat surface and rub the edge longways on the sandpaper til it's smooth. Goes very fast, and can clean up even wandering edges. Or you can simply score the PCB stock several times with a box cutter and metal straightedge, then snap it off. The edges sand quickly on that. Dulls the blade QUICKLY though.

[JHow]

Super neat and tidy job. I like how you mixed the green and brown on the heaters - makes it easier to tell which is which.

[Tom Phillips]

Mike,
You could cut a copper strip from Cu sheet or use heavy gauge copper tape and put it under the board with the eyelets sticking though it then colder the edges of the eyelets. This would hide any rough edges. The copper can be cut with shears or heavy scissors. However, I'm just thinking out loud here. Issues are:
1) unless you trip across the proper material the min buy cost is high and 2) It's starting to seem like a lot of work for little benefit.
Have Fun,
Tom

[Ronsonic]

Your buss bar will suck up a lot of heat in soldering. No biggy. Just use a substantial iron and have the hole and solder up to heat then insert the wire to spare melting insulation.