The PAX PX-8 Echo Chamber (Tape Delay)

Here’s a new addition to the Studio Nebula family. It’s a “PAX Echo Chamber”.

PAX PX-8 Front Panel

The PAX PX-8 Echo Chamber Front Panel.

I can’t find any image or reference to this exact device anywhere on the internet. It appears that this PAX PX-8 is functionally identical to the “SOLEC SE-3″. There are other PAX PX-8 machines with a black face, which appear identical to the SOLEC SE-8. After finding some pictures of the SE-8 on the web, it appears that the black-faced unit offers continuously variable tape speed (delay time) control, while this earlier unit uses a 6-position switch.

Unfortunately for me, on my unit the first 4 positions are all the same speed – meaning my Pax has only 3 possible delay times. I’m not going to try to repair it, I’ll mod it instead.

It sounds surprisingly nice. I expected a lot more noise, and I also expected the echo quality to degrade rapidly if left continuously repeating. I am beyond pleased with how nice it sounds … perhaps even “tickled”.

Still, this unit needs a couple of important modifications:

  • Conitnuously variable Tape Speed. The motor is connected to the circuit board with 3 wires. The label says the motor is powered by 13.2 VDC. I think I’ll use a potentiometer wired to a transistor to vary the voltage supplied to the motor.
  • Effects loop mode.The dry signal is always present at the output jack, and it’s quite a bit louder than the delayed signal. This is OK for in-line use with an instrument, but not suitable for processing an effect send. I’m thinking the best solution is to add a pot to attenuate the dry signal. This way, I’ll be able to turn the dry signal down to zero for fx loop mode, and if I’m using it in line with an instrument, I’ll be able to get a wetter instrument-to-echo ratio.This echo is in really good shape cosmetically, so I am reluctant to add any controls to the front panel. Replacing the rotary switch with a pot won’t change the device’s appearance, but the “dry level” is an additional control. It is unlikely that anybody would want to adjust the dry level during normal use – I see it as a set-and-forget knob, so I guess I’ll put it on the rear panel, in the cord compartment, near the tape cartridge.

I was quite taken by this cool-looking thing when I first saw it. Still, even though it’s in excellent condition, I think I probably paid too much.

The seller lives in Mississauga, and he reminds me a lot of … me. I hope to interact more with him in the future.