Boss - FA-1 Fet Amplifier  [schematic]

All about modern commercial stompbox circuits from Electro Harmonix over MXR, Boss and Ibanez into the nineties.

Re: BOSS - FA-1

Postby iq01221 » 06 Dec 2011, 04:41

Duckman wrote:C'mon guycapuano! Give it a chance! The DIYLC program it's not hard at all and you'll be satisfied doing it by yourself :horsey:

Actually, it gives it an "extra" point in your build. Word!
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Re: BOSS - FA-1

Postby roseblood11 » 09 Dec 2011, 21:49

Who can explain what C13 and C14 do in the original pedal? Somehow I remember that they are "for stabilization", but what exactly does that mean and what influence does the chosen value of those caps have? Will a pedal that replaces the HA1457's with a 4558 really sound identical?
http://ustomp.com/files/fa1schematic.pdf

btw: just doing a vero layout, because I'm too lazy to etch a pcb...
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Re: BOSS - FA-1

Postby Duckman » 10 Dec 2011, 00:32

C13, C14 are just to prevent some annoying oscillation in the IC as other single OA based circuits like Distortion+ or Rat.
A bigger the cap can roll off some high end, if I'm not wrong.
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Re: BOSS - FA-1

Postby Duckman » 10 Dec 2011, 00:35

"A bigger the cap"??? Geez! :lol:

Sorry, I mean "a bigger cap"
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Re: BOSS - FA-1

Postby roseblood11 » 10 Dec 2011, 02:07

Unverified:
Image

I added R17, as shown in the schematic at buildyourownclone.com. But I guess it would lower the input impedance significantly. Leave it out or use a much higher value...

For this message the author roseblood11 has received thanks: 2
guycapuano (10 Dec 2011, 03:48), joeboo88 (10 Dec 2011, 02:12)
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Re: BOSS - FA-1

Postby guycapuano » 10 Dec 2011, 03:48

Wow thanks Roseblood, I heard a friend of mine was making a break out box for me for Christmas so, when that shows, if this is not verified yet, i will give it a go.

And if a more experienced dude verifies it, then I 'm all over it! :applause:

Thanks bro.
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Re: Boss - FA-1 Fet Amplifier

Postby roseblood11 » 19 Nov 2017, 21:36

Nice. But you used a font in the layout file that isn't embedded. Those, who don't have that font installed, can't read the text

By the way:
My vero board layout is verified!

Image
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Re: Boss - FA-1 Fet Amplifier

Postby kingmafw » 24 Nov 2017, 22:01

Gandalf_90 wrote:I was asked to build the next BOSS FA-1 replica, so I ordered a PCB according to my design. Today I got it! :D


Do you also sell the PCB's or are you just building complete FX?
it is mei sizzen net to dwaen

Johannes Harald Kingma - FWS Pedals - Germany
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