Thanks, Barry.
Yes ... however, if I understand your suggestion, that will not supply
the required bias voltage, just provide a connector for it - I still
need a source for that voltage. (Sorry if I missed something in your
post.)
I think I have two options...
1) Replace the existing panel jack, and draw the required 2.5-5 volts
bias voltage from the existing circuit (perhaps borrowing it from Pin
2 on the 8-pin connector. I could probably wire that up, but I do
not know if that would cause any problems in the circuit I cannot, with
my more limited knowledge of circuits, foresee. While I know it would
power the microphone, I don't know what adding 5 volts to the jack tip
line would do to the rest of the circuit.
(Note... that would provide 10 volts according to TT
specifications, and I would probably not only draw
the voltage from there, but also step it down by half.
These computer microphones only "like" 2.5 to 5 volts
bias voltage typically.
Or
2) Use an external battery box that provides bias voltage for this type
of thing. AndreaElectronics makes one, and I think there is one either
included with or available for the Yamaha set. I have some older ones
in the parts box, left over from some older AudioTechnica and
RadioShack lavalier microphones. I could easily make such a battery
box, I suppose, if I could figure out a schematic for one. It cannot
be too difficult to apply 5 volts to the sleeve on the plug to energize
the mic capsule ?
http://andreaelectronics.com/Buy/ProductDesc/APS100.htm
Comment --
I am just plain surprised (and obviously disappointed) to discover
TenTec put a MONO jack for a DYNAMIC type microphone, instead of the now
ubiquitous and pervasive (i.e.. MORE COMMON) electret type computer
headset.
TenTec said the jack was intended for the "popular" headsets, like HEIL
sells... But, while HEIL does sell dynamic microphones, but I cannot
recall ANY of its cables terminating in a MONO 1/8 inch plug. I had
blithely assumed TT had provided a three-pole STEREO jack, to
accommodate what IS the more common electret condenser type computer
headsets, like the truly popular Yamaha CM-500, and others like it. A
1/8 inch MONO plug for a dynamic mic is hardly the common trend, and not
found on popular headsets.
I plugged in an old Shure HW-501 dynamic head worn microphone (mic, but
no earphone receivers) which terminates in a nice old fashioned
two-pole 1/8 inch phone plug -- and it sounds buttery smooth on the
circuit .... but this is hardly a COMMON arrangement as TT claims.
I am supplying Koss SB-45 headsets to the contest station instead of the
Yamaha model. No offense and no complaint with the Yamaha set, but the
Koss models are $20 cheaper and sound just as good. Oddly enough the
Koss SB-40 looks just like the Yamaha CM-500, bu the Yamaha model now
uses an electret condenser mic capsule, while the Koss model still uses
a dynamic capsule. That would work swell on the Model 715, but dynamic
computer headset microphone capsules are certainly the exception these
days.
----------------
Happy Trails.
======================= Richards / K8JHR =========================
On 5/26/2011 12:21 PM, Barry N1EU wrote:
I would just buy a plug that mates with the 715 front panel mic jack
and wire it to a stereo 1/8 in jack to plug the CM-500 into so your
mic audio and bias are handled like on the K3 rear panel jack that
you're familiar with.
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