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Why do some pedals just sound awesome

Started by Adam_DIY, June 21, 2016, 12:26:59 PM

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matmosphere

Quote from: Cortexturizer on June 21, 2016, 09:49:20 PM
It's a bitch to build on vero in comparison to pcb but there is something about it, seriously.

Vero isn't to bad, so long as the parts count isn't to high. I hadn't built on vero for over a year until my last two builds. Going back I was actually surprised at how easy it was to work with. It is certainly more convent than pcbs, because I don't have to wait for a board in the mail. The off board wiring can get a little tiring though.

Moral of the story, get some parts and build another one on veroboard and see if it has that magic mojo.

alanp

Layout can make a difference in high gain, or circuits with clock signals.

I'd like to know whether the vero layout worked from the same schematic and values as the pcb, if it sounds better :)
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sturgeo

Interesting, i wonder if its down to the trace widths against the track width on vero, not sure about the copper weight and quality difference between the two but i had always assumed (most likely wrongly) that the sort of currents we're dealing with in pedals, this shouldn't be an issue  :-\

DPTX

I think layout does play a role, especially in high gain.  My vero board stuff looks much different than a PCB layout.  I know when I build amps layout plays a huge part. 

I usually use vero for everything (except my phase 90 clone, that's a PCB), and I always change the layout between builds for various reasons. 

I'm guessing it's parts tolerance.

Adam_DIY

Quote from: alanp on June 22, 2016, 03:36:31 AM
Layout can make a difference in high gain, or circuits with clock signals.

I'd like to know whether the vero layout worked from the same schematic and values as the pcb, if it sounds better :)

The pcbs are a Queen of Bone (in 9V), a ballbreaker from fuzz dog and Ivlark's vero layout from Tagboard effects.

thesmokingman

ok that sheds some light ... if you followed the individual BOM for each of those, you could end up with pedals considerably different(I'm not going to compare, you can). if each of them are identical, then tolerance would come into play
once upon a time I was Tornado Alley FX

EATyourGUITAR

beside the obvious one that is part tolerance, there is also the silicon lottery. the third thing that I think people are mostly missing or skeptic is the induction. all kinds of induction. everything is an antenna. we are playing with high gain audio amplifiers. ceramic caps create and are influenced by magnetic fields. but lets also be realistic, the induction depends on the presence of AC magnetic fields from both inside and outside the case. a shielded enclosure will mostly only get RF on the cable so there is a length of cable there that is radiating RF before it reaches the first RC low pass. RF + high gain can steal headroom if it is not filtered properly. even if it is it is not since it radiates from the jack to the switch. the more you RC filter this the more you increase the RF load through the wire (also an antenna) this also increases the current through the wire. I built a pedal with a LM386 into a TL072 and it was notorious for induction. this is a function of sensitivity to picking up noise and currents being used by the LM386. it makes no difference if the ripples are generated and picked up in the signal or in the power. for single ended signals the feedback loops are the same result with high gain amps. it does not matter if the noise is coupled to the power rails or to the signal and one of the power rails. it will be amplified at each gain stage. there is ground at 0 Ohms theoretically ideal and then there is ground at G > 0 Ohms. there is wire at 0 capacitance and then there is real wire including the leads of the part have C > 0. don't forget L > 0. all your transistors and opamps have different ground this is exactly what is coupling the induction and power ripple between builds. usually this is very very low less than 1 Ohm but a solder joint can vary depending on oxidation of the PCB and component leads. no one ever notices or records measurements of oxidation that can be as high as 10 Ohms or more even worse on the power or a transistor with beta 100+. you can sort all these things out but you really can't sort the silicon lottery past a point of Hfe and I know that manufacturer, part number and Hfe do NOT tell the story when you are trying to make consistent guitar pedals. it is much deeper than that. you need 4 dimensional data sets, not worth it to check a batch or to check a part. thats where I give up.