F5 Turbo Circuit Boards

[eyoung]

IF YOU ARE LISTENING ON THE EDGE, MAYBE YOU NEED DIODES...
THE EARS HAVE IT . WE NEED SOME AUDITORY RESPONSE....

LISTENING IN THE BACK ROW....EL

[a.wayne]

So what no diodes now ...? ...

[bear]

My only perhaps useful comment is to make the pads for the small stuff as BIG as possible, especially if there is the potential for having to take parts in and out.

Also make the traces on the small stuff NOT as thin as possible, actually make them as thick as reasonably possible.

The trend is to make these boards with thinny thin thin thinny traces because you see it in commercial PCBs where they try to slide traces inbetween things like IC pins. Bad idea for audio, imo.

Imo, FAT traces and BIG pads are good. traces as wide as the pad are fine.
( I prefer a jumper or two over thinny traces )

On the pads, alternately make them oblong rather than just a single pad diameter...
hard to illustrate in ascii, but, single pad = o oblong pad = ooo hope that illustrates the idea...

YMMV.

_-_-bear

[jackinnj]

Don't gold plate the copper -- I've fixed F5's and F4's for folks who've had bad solder joints on gold-plated boards.

[bear]

Really?

Hmmm... seems unusual Jack.
What solder was used?

I get good wetting on all the gold I have ever soldered, afaik.

Curious.

_-_-bear

[AuroraB]

What is it with some of you guys and this "gold plated is sooo much better" mentality?
Gold is inferior in conductivity to both copper and silver. Gold rules in corrosion resistance, in harsh environments, and is very well suited for "finger type" and clamp-down type connectors where the gold surface is one of the two contact points. Otherwise gold sucks, and is not a very solderable surface.
Soldered gold pads are usually avoided in high-tech instrumentation.

[Bksabath]

Originally Posted by eyoung

IF YOU ARE LISTENING ON THE EDGE, MAYBE YOU NEED DIODES...
THE EARS HAVE IT . WE NEED SOME AUDITORY RESPONSE....

LISTENING IN THE BACK ROW....EL

Hi mate.

Absolutley agree with you
As evvery time I try to post same definitive numbers I get flied and give a chance to cumpolsory poster to fell superior I was asking questions insted.

There are to many factors involved for straight answer

One need to consider
Normall max listening volume (Search for Pano tread to get Idea)
Impedence of speakers (normaly much worst than rated especialy at low frequency where signall normaly present maxymum energy demand)

Those will be values that aply only to each individual case

In my case I have Polk LS15i nominal 4 homs in my smalish room 87dB is fine after Pano test I will rarely ask the F5 to give me more than 12 rms out

The music I listen to is mostly not Classical so dinamic range is not big issue.

I am quite happy with 35 volts rails and Bias of 2.5 A on each rail

Yess at time the amplifier will go in to class B but I do not think I will be able to distinguish the difference at such level

I still have the option of going balanced for 3dB more head room (Ops there it cames)

This will be different from one having 40 V pluss rails when diodes became needed maybe

Or someone with home made super duper speakers with 90 + dB efficency and impedance curve that gos down to fraction of homs.

[flg]

The difficulties with gold are ussually the type of plating that is done. There is electrolisis gold and some other palting method(Brain Fart). Personally, I agree with some posters that gold plated PCBs are extra raz-ma-taz that does not improve anything except the vendors pocket! Solderability sucks! (especially electrolsis gold) and it grows wiskers(just pretend your a space satalite) etc.etc.
The most important factor in PCB construction for our audio circuits, other than layout related crosstalk issues, is low DCR and inductance along with the ability to cary away unwanted heat from components! That boils down to wide, 2 3 or 4oz. copper! And, good vias!
just my 2cents

[MEGA-amp]

Being that this is the "Turbo" version, my vote would be 4 layer/4oz copper, and big fat power traces. I like my boards robust!......my 4cents

[chchyong89]

Originally Posted by MEGA-amp

Being that this is the "Turbo" version, my vote would be 4 layer/4oz copper, and big fat power traces. I like my boards robust!......my 4cents

I don't see a point using 4 layers in this PCB. The fabrication fees need to concern too.