Flatline v1.1

The first version of my Flatline PCB worked well but had a couple of small problems. Check out my original post for more information about the Flatline Compressor. 

I fixed the issues with the original PCB, and had some boards made through PCBWay.com. The cost is only $5 for 10 boards, so it’s perfect for prototyping. The first board had a couple of issues with part footprints and silkscreen. 

After building and testing, I noticed the first build worked well, but the new build had some distortion. It sounded like op-amp distortion and not the good kind. The only difference was the board and the diodes.

I used Ge diodes for this build, which are specified in the original schematic. The diodes were these D9B types from Stompboxparts.com.

The diodes I used on the first build were fake 1N34a types. I got them at Futurlec.com. It looks like they don’t sell these any more but, it looks like you can something similar from Amazon. 

These are silicon diodes made as workalike diodes to replace the Ge 1N34a. I replaced the Ge diodes on the new build with these, and it sounds much better! No more distortion. Not sure what is going on here.

Now both builds are sounding pretty good! This is a surprisingly effective compressor for guitar that is cheap and easy to build. I would recommend building this project if you want a simple effective compressor. Don’t build this if you are looking for a studio compressor with many options.

Parts List

C1	1n
C2	100µ
C3	10µ
C4	100µ
C5	10µ
D1	Ge
D2	Ge
D3	Ge
D4	Ge
D5	LED
D6	1n5817
IC1	TL072
R1	330r
R2	10K
R3	10K
R4	47K
R5	10K
R6	10M
R7	10K
R8	220k
R10	4K7
R11	10M
SUSTAIN	A100K
VOLUME	A100K
VACT_1	VTL5C3 (or better, any LDR+LED)