Canford Audio Active DI Box oddities

[Solstace]

Hi

 

I have five Canford Audio active DI boxes here anywhere between 5 and 10 or more years old, and they are all reported to be suffering the same kind of problems:

• Distortion of input, especially from laptop headphone outputs,
  
• changes in tonal response - bass/treble get rolled off, varying over time during a soundcheck
  
• Constant issues with loop-through being intermittent.
  

 

The only problem I can reproduce at the test-bench (even in the same system with the same cables, instruments etc) is the distortion. It's not quite related to the input level either - it seems dependent on the overall frequency balance of the input. Mid-heavy material is worst for this. High levels of bass or treble frequencies don't upset them. They'll also pick up random bursts of what sounds like RF interference.

 

Otherwise all units perform correctly with all cables (themselves tested good), with pads, attenuated inputs and (un)buffered loop-through outputs working correctly. These issues occur on any system of ours that we use them with, so it's not like there's a single dodgy phantom supply or anything similarly obvious I can think might upset them.

 

Guess I'm just wondering whether anyone here has noted similar issues with these, and whether there's a known cause? I'd call Canford for help, but don't have the time to hold a phone conversation, and it'll likely be too tricky to get email efficiently to the right place in good time, hence bringing my question here...

 

C.

[ramdram]

Solstace, are you able to follow the circuit between the pass through sockets? Any duff connections?

 

Ref the distortion; are you able to meter the individual components? I get the impression there might, possibly, be probs with the RC networks, assuming there are any of course.

 

Being an active DI box the phantom power may be processed through an dc/ac converter, thence to a transformer then an ac/da converter and on into the op amps. Possibly the prob lies in the power supply chain.

 

The Canford site describes the boxes (assuming you actually have the same boxes?) as being battery/phantom powered. If possible have you tried battery only?

 

I appreciate trying to solve a prob via the forum is problematical in itself but it may pay you to seek advice from Canford.