Flatline by John Hollis

Flatline by John Hollis

This is a really great little compressor from John Hollis. Follow the guide here to build it yourself. Check out this post to get the background on this project and learn about compressors.

Order PCBs

Schematic

Partslist

R1330r
R210K
R310K
R447K
R510K
R610M
R710K
R8220k
R9
R104K7
R1110M
D1Ge * see notes
D2Ge * see notes
D3Ge * see notes
D4Ge * see notes
D5LED
D61N5817
C11n
C2100µ
C310µ
C4100µ
C510µ
LED/LDRVTL5C3 * see notes
VOLUMEA100K
SUSTAINA100k
IC1TL072
  • Diodes – The original circuit shows Germanium diodes. I had better luck with silicon 1N34a workalike types which are silicon. I suspect this circuit will work with almost any type of diodes. When I used Germanium diodes I was hearing some op-amp clipping. Changing to silicon diodes the noise went away.
  • R9 – There is no R9
  • LED/LDR – I used a VTL5C3. Seems a lot of people have success with this part. The key seems to be using an LDR with a slow decay time. Check out this post for more info. Works best with a LDR that has a large light history. The decay time of the compression is determined by the decay time of the LDR. You want an LDR with a long decay time.

Use these wiring diagrams.

Here is a drilling guide you can use. It is sized for a 1590B enclosure.