Request for prescription electronics cob part list

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Lovemusic79
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Post by Lovemusic79 »

Hi
I wanted to ask for info on building a clone of prescription electronics clean octave blend pedal.
What type of capacitors are used in the original circuit?
From the pictures I can see that p.e. had used green mylar and also blue type.
There is a clear capsule with a tin foil inside it. What type is that?
What type of capacitors are used?
Thank you
Howard

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dv8r601
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Post by dv8r601 »

Those would be styroflex (polystyrene) they are generally used for the smaller value caps but I've seen them up to 100nf. I've seen a few different type caps in these from the cheapo green Mylar chicklets to the blue poly 7.5mm pitch ones. He also uses the basic 1/4w carbon film 5% tolerance resistors so I'm thinking its not a picky pedal. In all honesty the type doesn't matter much in these kind of pedals, the VALUE is what needs to be right. I've built.
pedals with just mlcc caps and made the same pedal with Panasonic ecq-v and there is hardly any difference in sound. Component tolerance may account for certain differences, but there isn't much to.the mojo craze other than how it looks.

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mauman
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Post by mauman »

+1 for dv8r601's perspective on caps. It's the the value that matters. I usually measure mine before installing them and make a note of the actual values along with the nominal (listed) values, since caps usually have a bigger tolerance (up to 10% or 20%) than resistors (5%, 1%, etc). There is some evidence that single-layer ceramic caps can be microphonic (pick up physical vibrations) in some situations, so I'm careful about using those in the signal path. And I tend to use higher voltage ratings than necessary for electrolytic caps for longevity, but that's about it.

I just built a COB for a friend, and found that the choice of the four transistors had the biggest impact on the sound. There are some good threads on that topic, or let me know and I'll post my notes.

Regards, Mike

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