The one I have is called a 3-channel headphone Volume booster. That's what
it says on the little gizmo. Bought it at RadioShack
for about $20. Runs on those annoying little batteries. I plug it in
the computer or transcriber, where I would normally plug the headphones. Then
I plug the headphone in one of the channels.
All it does is boost the volume, not improve the quality. The 3-channels
means you can plug more than one set of headphones
in at one time. Not often needed, but when I can't understand something, my
husband and I can listen at the same time. That's the only time I can see a need
for it.
I believe
Martel has something a little more expensive that is supposed to also improve the quality of the sound. That is
probably the equalizer.
I can't remember where I bought mine, but I did a search for EQ50 and Koss and price-shopped. Mine was much less than
$20.
I also have a Koss stereo equalizer that fits between the transcriber and the earphone. Sometimes it helps to filter
out some of the garbage with bad tapes.
I also bought two Equalizer thingies and that didn't help either. The headset says it is included, but there is nothing
hanging from the wire, just an extra long wire. I bought a Koss thingie and a Radio
Shack thingie, neither one worked.
Along the same line as the KOSS product, Hearsay Corporation makes the Speech Adjust-a-Tone, and I have their
catalog. I LOVE mine. Kinda pricey, though, at $149.95, as compared to $29.00
for the KOSS one. Mine has two controls apiece for bass, middle, and treble
tones, whereas the KOSS shows one for each. Anyhoo, since I deal strictly
with transcription at this point, it's been well worth it. Has an optional adapter so
ya don't have to waste your coins on expensive 9V batteries too.