A couple of weeks ago I saw an ad for a Great British Spring reverb. The Great British Spring is a famous 1980s stereo spring reverb unit created by Bandive. (Used by , for example, Portishead on the album Third) It has a bit of a weird appearance since it’s entirely built into a drainpipe. I had wanted an analog stereo reverb for a while and this was a nice opportunity to get one at a good price. The owner said the PSU was broken and no sound was coming out. Sounded like a fun little project, I thought.
The GBS luckily arrived intact by mail. It’s quite a hefty thing, and since it’s made of plastic I was afraid it might break. Once I had the GBS in my hands, I was surprised by how sturdy the drainpipe actually was. That wasn’t going to break easily.
Pins and PSU
The GBS came with a 24V adapter that was half taken apart and connected to a DIN plug on the GBS. The GBS also came from the factory with a DIN plug. You could connect that to an external power supply from Bandive itself. Unfortunately that wasn’t included, so I decided to just get a different 24V adapter myself and pair it with the existing DIN plug.
I first decided to hook the GBS up to my lab power supply to see if there was still some life in it. That seemed to be the case. It drew about 25mA.
Would any sound come out?
I decided to test it with some XLR to jack cables plugged in via my patchbay. Unfortunately it stayed eerily silent when I sent some audio from Bitwig (DAW) to the GBS.
I decided to open up the GBS and saw a PCB board that still looked to be in fine shape. I didn’t spot anything odd at first glance. I decided to inject some audio using my function generator, and with my audio probe on the output I tried to pick up the signal.
What stood out was that on pin 2 the signal didn’t come through, but on pin 3 it did. After reading up on this, it turns out that before the early ’90s some manufacturers used pin 3 instead of pin 2 as the “hot” (signal). So if you use, say, XLR-to-jack cables, the signal from your DAW gets sent via the tip of the jack. That then arrives at pin 2 of the XLR, which goes straight to ground. So that’s not going to work…
I considered modifying the XLR sockets so pin 3 would become hot, but that wasn’t so easy since they were soldered to the PCB. Instead I decided to just make some new XLR-to-jack cables where the tip of the jack is connected to pin 3 of the XLR, and the sleeve of the jack to pins 1 and 2. This worked perfectly.
In the end I got a 24V adapter, put a DIN plug on the end, and connected that to the GBS’s DIN plug. (Of course, carefully checking which wire is positive/negative.) Gave it a good clean, and voilà, another little job done!
