There is PCB and then there is PCB

[Jared Purdy]

Hi, I'm trying to understand more about PCB, and what makes a good one (and who uses them), from the run of the mill. Amongst the amp companies that are using PCB, which ones are using the best platforms and methods?? Mesa? Fuchs, Soldano? Freyette?...??? None of the above? Thanks.

[Jazz P Bass]

Exactly what stage of manufacture of the printed circuit board are we critiquing?
None of the manufacturers "makes" a PCB.
1-The amplifier engineers will design the circuit, specify the PCB copper thickness & hand it off to the layout guy.
2-An engineer will "layout" the circuit board & send it as a Gerber file to the board house.
3-The board house (outside vendor) will "etch" the board.
4-Then it goes to assembly to be "stuffed" & soldered.
There are many ways to make a good or bad board.

[mooreamps]

Not sure how to answer this question.. Here in the Silicon Valley, there are more board shops than you can shake a stick at.. All of them are good and all of them are world class pcb board makers... But, the overall board performance is always going to be limited by who ever does the layout for the card.. The card makers have no control over this.. Their only requirement is to build to whatever gerbers are given to them...

-g

[Jared Purdy]

Thanks, that`s more than I knew 15 minutes ago. Okay, the companies that I mention all proclaim to be top notch, bordering on boutique (Mesa bills themsleves as boutique!). So they do al that you specified, whats the outcome? What makes a good PCB, and who does it??

[Jared Purdy]

Are the "card makers" (interesting term - knew I'd learn a lot by posting this!) working for the amp compaines? I.E., Mesa, Soldano, Fuchs, etc?

[mooreamps]

I don't know.. I am guessing not given the infrastructure required to make a pcb.. It would be more cost effective to contract that out.. Even a giant company like Apple computer contracts out their pcb's.. But, in my opinion what makes a good pcb is the guy [or gal] doing the artwork, and quite honestly ; that's not that really tough to do..

-g

[Jared Purdy]

I have read somewhere, on one of these forums, that there are single sided, and dual sided?? Am I on the right track here?

[Jazz P Bass]

I new we were going there!
Whether or not a pcb ends up being double (multi) sided or not depends on a number of issues.
-Can the circuit physically be laid-out on one side of the board. (think older Peavey amps)
-Does the hardware require double sided attachment points (for durability & workablity).
Any issues have to addressed by the person laying out the pattern on the pcb (software driven for sure)
Hopefully the different departments work together when a design is in progress.
And then there are the bean counters.
And the crappy solder machine operators.
And the misguided assemblers.
.......

[dai h.]

go to R.G. Keen's GEO. There is an article or two there. Also Bogner Amps site. An article by Andy Marshall of THD there.

[R.G.]

You beat me to it, Dai.

Go look at Geofex, especially Point to point versus PCB amps - Better tone??

In a high gain, high impedance signal environment, all the analog layout matters. Lots of amp makers say "point to point" like it's a secret incantation from a holy book and "PCB" like it's a dirty word. Neither is true.

The basics are easy. Good PCB work, like good tagboard (which is not point to point) work depends on
- making it mechancally rugged and resistant to bumps, jolts, and vibration
- NOT making the electromechanical controls stress fragile solder joints
- NOT making the PCBs a PITA to get to to service
- NOT getting the signal routing permanently wrong on the PCB

I have personally done a PCB based tube amp with these targets in mind. Worked well.
Go read the stuff on GEO and ask further questions.

[Jared Purdy]

Thanks for all of the replies. I was out last night, and as such did not have the opportunity to read those sources that were mentioned. I'll do that this AM. Thanks again!

[mooreamps]

The basics are easy. Good PCB work, like good tagboard (which is not point to point) work depends on

- NOT getting the signal routing permanently wrong on the PCB

You mean like on the Epi Valve Junior Version 1 before they went to dc filaments ; and had that annoying hum problem ? :|


-g

[Jared Purdy]

Okay, I read it. I'm not sure how much I understand, as I wasn't paying attention to a lot of the details. The one thing that the author mentioned, and this might be of relevacne to the original post, is PCB thickness, and other build techniques that the aforementioned amp compaines use?? Do they use good PCB boards and wiring techniques? Two of them make fairly complicated amps (Freyette and Mesa). I forgot to add Boger and Egnater to the list. It woudl seem that only the largest companies woudl be able to afford PCB given the design and technical issues of producing the boards.

[Steve Conner]

Not really. I regularly do PCBs for my own projects. I just splashed out on a couple of 4 layer ones for hi-fi amp output stages, because I thought they would deliver better sound than hand wiring. Yes, you read right.

It's usually a money pit. My boards cost me about $250. But I have had popular ones where I was able to do a board run at Gold Phoenix in China, sell the boards I didn't need to other hobbyists, and get my own boards for free or even make a profit. At the place I used to work, I had boards that were covered in surface-mount parts, manufactured in batches of 100, and PCB was a complete no-brainer there. Out of 100, maybe 95 or 97 would work, and the ones that didn't just got thrown in a box to fix when someone got around to it. We had 6 employees, a good deal fewer than Fender.

I've always laid out my own circuits, but recently I started working with a layout guy. It makes life harder in some respects, because I have to keep an eye on him and make sure he doesn't route some critical signal a funny way, like the Valve Jr's heater wiring. Normally we will have a few goes back and forth before I approve the Gerber files.

Really it's nothing to do with point to point vs. PCB. PCBs are good enough for spacecraft, fighter jets and missiles. It's good design vs. sht design. Fryette, Mesa, Bogner and Egnater should all be top drawer stuff.

[Jared Purdy]

I think that's it, I mean the good design vs bad design. I think that people too often associate an amp that they don't necessarily like the sound of - if it's made with PCB - as being a crappy amp, when it may just be the design, cap values, speaker, etc. The Fender RI's get a lot of that bad rapping. It's not that they are "bad" sounding, but they don't sound like an original, and combine that with some questionable design matters to cheapen the cost, and you've got people calling them "crap". And the list goes on.