[TenTec] New Orion I v2 Firmware version: 2.062a

[Kevin Purcell]

The other thing to consider is good old fashioned cross-over  
distortion at low audio levels.

This seems to be the reason TT suggested a pad (of a couple of  
hundered ohms) in series with the headphones with older equipment. I  
would have though the AF output amp was better in a multi kilobuck  
Orion but perhaps not.

I also wonder if an AF amp in crossover distortion will rectify stray  
RF too?

There was a report of a similar issue (Darth Vader voice on an Argosy  
in headphones) in the last month.

Either way I'd try the couple of hundred ohm resistor in series with  
the headphones (build a little adaptor it will be hand on other rigs).

Or "ancient" high impedance headphones!

On May 26, 2007, at 9:34 AM, Dr. Gerald N. Johnson wrote:

> Could it be that the modern low impedance (4 to 8 ohm) headphones take
> so little voltage drive that turning down the DSP headphone drive  
> leaves
> it using so few bits of the digital level that you hear the  
> granularity
> of 4 bit audio? The Trimms would be high impedance and take more  
> voltage
> to give enough power to be heard and so use many more bits at the
> digital level, maybe 14 or 15 and so the digital granularity would be
> hard to hear.
>
> Could it be that the low impedance headphones need to be driven  
> through
> a 250 ohm resistor? Or a 50L6 output transformer (2K to voice coil)?

--
73 DE N7WIM / G8UDP
Kevin Purcell
kevinpurcell at pobox.com