TC Electronic - Spark Booster  [traced]

General documentation, gut shot, schematic links, ongoing circuit tracing, deep thoughts ... all about boutique stompboxes.
alexradium
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Post by alexradium »

miklax wrote:By the way..

What do you think about the active filter section?

Any Idea on how to calculate the corner frequency for each of the switch positions?

https://www.dropbox.com/s/l1p41wjfl27o8zq/Untitled.jpg

Cheers!
http://www.muzique.com/schem/filter.htm

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coldcraft
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Post by coldcraft »

185Hz and 408Hz
Black Dynamite wrote:you need to shut the fuck up when grown folks is talkin.

miklax
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Post by miklax »

coldcraft wrote:185Hz and 408Hz
Could you explain, or show the math?

Cheers!

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Post by johnk »

just plug the resistor and cap values into this calculator:
http://www.muzique.com/schem/filter.htm
3K9/.22uf= 185.6
3K9/.1uf= 408.3

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Post by johnk »

BTW, I drew up a veroboard layout for it, but it's huge at 33x18 so it won't fit in a 1590B. I would probably fit in a 125 but i'm just going to use a 1590B.
if anyone is interested, i'll post the layout after I build and verify it.

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Post by johnk »

I got the vero version built and it sounds great! thanks for posting the schematic.

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Post by johnk »

my vero is pretty huge at 33 x 18, but at least it's verified. :wink:
I preferred mine to have a more open top end so I removed C2 (1n cap from miklax's schematic), but it still shown on my vero (second 1n cap from the left).

Image

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Post by miklax »

Great Work!!
I'm glad to finally contribute to this community, that helped me so many times!

When I built mine.. and despite the fact it already has 1M resistor on the Input, and 100K on the output.. It still makes a very loud Pop noise using a regular truebypass wiring..
Any ideas?

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Post by johnk »

that's strange. mine makes no pop at all when using a true bypass.
thanks for posting the schemo!

if yours is popping, i'd first make sure that the VR+ connections are going to the right places, otherwise it it'll put DC on the output and cause huge popping.

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Post by miklax »

I'll look for it... but i'm using a PCB, designed directly from the schematic.
I'll analyse it further! :)

thanks for the input.

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Post by fixxe »

Quick question: On the pictures the chip is mc33178 and on your vero layout it is 33172. Are they the same?
Also miclax named them OPA2134PA. So what's going on there? :cry:

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Post by johnk »

I would think that any dual low noise opamp will work in it.
i'll order some 33178's to try in it and see if it makes any difference but I doubt that it will.

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Post by fixxe »

Thanks for checking that out! :thumbsup

Should't the IC still be changed on the vero layout though?

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Post by johnk »

IMO, it really doesn't matter but here you go:

Image

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Post by fixxe »

johnk wrote:I would think that any dual low noise opamp will work in it.
i'll order some 33178's to try in it and see if it makes any difference but I doubt that it will.
Any updates?

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Post by johnk »

I finally just got them so i'll try the 33178's in it soon.

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Post by fixxe »

johnk wrote:I finally just got them so i'll try the 33178's in it soon.
What's the verdict? :)

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Post by johnk »

fixxe wrote:
johnk wrote:I finally just got them so i'll try the 33178's in it soon.
What's the verdict? :)
sorry it took so long but I finally got around to trying the 33178's and it sounds the same as the 33172's so i'll just leave them in there since that's what the original has in it.

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Post by fixxe »

Cool! Thanks for taking the time to compare them!

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Post by copachino »

johnk wrote:IMO, it really doesn't matter but here you go:

[ Image ]

thanks, would be amazing to have a pcb layout, or maybe and OSH park shared projecto fot this little big monster

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