Hairball FET/500 Rev D Compressor Build

 

FET/500 Rev D PCBs populated.

I built a Hairball Audio FET/500 Rev D kit to get the hardware 1176 experience in a compact 500 series form factor. I jumped in during a Black Friday sale price of $385. 

The kit had the highest parts count out of the few 500 series kits that I’ve built so far. The solder pads on the PCBs were rather small, comparable to ones found on DOA kits. The components were spaced out well, so I didn’t make too many inadvertent solder bridges. The assembly was fairly straightforward with a good online build guide and interactive build map on the Hairball website.

The calibration process could have gone a bit more smoothly. The trickiest of the steps was the gain reduction meter calibration with the adjustment of R540 (Tracking Adj) on the Main PCB. There is a hole on the meter PCB to access this trim pot, and it is the most difficult to adjust. I initially could not get the gain reduction to budge from 3dB when 9dB was actually present. I then read on the GroupDIY support thread that the R540 trim pot was a 20 turn trim pot. I had originally assumed that the adjustment range was within 1 turn.

Physically turning knobs as I react to what I hear is a major positive of working with hardware such as the FET/500.

Some audio demonstrating the effect of the audio path can be found here: link to files

I ran a snippet of mono drums through several pieces of hardware:

1. Bypassed FET/500 as control
2. FET/500 No Gain Reduction 4:1 Att-9:00 Rel-3:00
3. FET/500 9dB Gain Reduction 4:1 Att-9:00 Rel-3:00
4. CAPI VP28 Unity Gain Mode
5. DIYRE EQP5 w/ EQ flat

I quickly did this to see what happened to a signal being passed through the FET/500 audio path without compression versus the CAPI VP28 and EQP5. 

To be continued.