by John Byrns <byrnsj@[EMAIL PROTECTED]
>
Oct 9, 2008 at 01:24 PM
In article <gcl4de$rpc$1@[EMAIL PROTECTED]
>,
Ian Thompson-Bell <ruffrecords@[EMAIL PROTECTED]
> wrote:
> cipher wrote:
> > Please continue the discussion and correspondance with me..
> >
> > This subject is still relevant as I still record quite frequently and
> > have found that the "commercially available" products out there just
> > dont tickle my fancy
> >
> > I am not a troll.
> >
> > -Cipher /Tynan
> >
>
>
> Hi Tynan,
>
> I recently purchased a DVD containing the manuals for a range old RCA
> and other tube based broadcast mixing consoles. One interesting aspect
> was that the earlier ones all had mic pres which were transformer
> balanced *out* as well as in. Mixing took place using 200 ohm bridged T
> stepped rotary channel faders connected to these transformers and the
> resultant mix fed into another transformer and amplifier. This meant a
> lot of expensive transformers and faders.
>
> A later model in the same series (RCA BC-6 series) dispensed with the
> output transformer on each mic pre, included a 100K (stepped) pot half
> way down the mic pre as a channel fader and a cathode follower output
> feeding 22K mixing resistors. The mix was amplified by the same basic
> mic pre topology with the group fader replacing the channel one.
This scheme to eliminate the output transformers from the microphone
preamplifiers starts to get complex when you consider stereo mixers with
the
need for pan pots. Another advantage of retaining the output transformer
is
that the same amplifier module design can be used for both the microphone
preamplifier function and the mixer output function.
--
Regards,
John Byrns
Surf my web pages at, http://fmamradios.com/
