[TenTec] Orion and Heil Proset QuietPhone Solution

[AL7CR]

Thank you to the many folks who responded with suggestions concerning this problem. 

As several of you noted the basic problem is that the Heil Headset has 220 ohm speakers and the Orion headset jack is rated to drive 16 to 32 ohm impedance headsets.  This was easily confirmed by connecting the Sennheiser headphones I use with my stereo receiver to the Orion.  These use 60 ohm speakers and the Orion could drive them easily to painfully high audio levels.

The most elegant solution (other than a new headset which I seriously considered) is to construct an impedance transformer to match the Heil unit to the Orion output.  The required transformers are around $12 each from Mouser plus the cost of connectors, project box, cable, and time.  What I chose to do instead was to purchase a $50 headphone amplifier from the local musician supply store.

The inexpensive headphone amps sold for use with portable music players get very poor reviews for audio quality, gain, and quality of construction.  I purchased a Livewire HA04 which received universally high marks in all these areas.  It is a small box and provides four individually adjustable amplified outputs of which I only use one.  It provides 1/4" stereo jacks for the input and output and runs on 12 v external power.  I discovered that the local music supplier is also a great source of inexpensive audio cables particularly those with  1/4" mono and stereo plugs.

The amp works perfectly and I am now able to hear the weak ones with my Heil Proset albeit at the cost of having yet another 12v interface box in the shack.

AL7CR