[sdiy] 45 vs. 90 degree pcb traces

rsdio at audiobanshee.com rsdio at audiobanshee.com
Sat Feb 15 00:14:25 CET 2020

Is there any documentation of the black versus red/blue Mylar tape process?

I’ve long assumed that the curved traces were hand-drawn with solder resist pens, or some other, similar process that was mostly manual. I also assumed that Mylar was cut with X-Acto blades. How would the black “crepe” tape be cut? … and how is the width controlled?

Despite the obvious pedantic tendencies, I actually believe it would be historically important to document these old processes. It seems that a number of computer history museums are gathering documentation of these early events, and I’d like to see PCB design as a part of that effort.


On Feb 14, 2020, at 11:39 AM, Harry <hbissell at wowway.com> wrote:
> Ok most of that is hooey! The curved traces were because the layouts were done with black "crepe" tape on Mylar. Curves are easy to do. That was superseded by red/blue Mylar tape which does not do curves. In  short, for audio frequencies there will be no difference. A good two layer or multilayer board would way outperform anything from the 1970's. 
> On Feb 14, 2020, at 2:10 PM, Harry <hbissell at wowway.com> wrote:

>> On Feb 14, 2020, at 1:50 PM, Jimmy Moore <jamoore84 at gmail.com> wrote:
>>> This came up on the AH "behringer RD-6" thread:
>>> >>Until the PCB traces are curvy (like on a 2600 or SEM) it's never going to sound authentic.   Electrons don't like corners.
>>> I had picked up similar folk knowledge from my first engineering job working alongside techs, EE's, and designers.  I went looking for a more technical explanation on why this is the case, and it turns out it is NOT: 
>>> https://resources.altium.com/pcb-design-blog/pcb-routing-angle-myths-45-degree-angle-versus-90-degree-angle <https://resources.altium.com/pcb-design-blog/pcb-routing-angle-myths-45-degree-angle-versus-90-degree-angle>
>>> (Notable exceptions being RF, high speed, or high voltage layouts)
>>> This and another <https://electronics.stackexchange.com/questions/226582/pcb-90-degree-angles> resource debunk the pcb corner myth on EMI effects.  
>>> Is there any other tangible (audible) impact this decision could have for music electronics?  I think not, but I'd love to hear from other more experienced engineers on this (hopefully not tiresome) topic.
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