orban Eq's
Daniel A. Weiss
Wondering if anybody can tell me the differences between the old Orban
621B parametric Eq and the 622B. Thanks in advance for the info.
Daniel A. Weiss
CC
stereo version completely redesigned of the 621B.
I mean the filters are true parametric constant Q. And great sounding.
I have had this unit for 20 years now in my studio and it doen't blush
when I turn on Protools. I just can't decide to sell it
Christian
Tom Baldwin
Richmond, VA back in the mid 70's. Mine still works but the pots are
scratchy sounding. I have never been able to figure out how to clean
them. Do you have any suggestions as to how to get rid of the dirt in
the pots? And yes mine is stereo blue front with grey knobs. Screw
post balanced terminals on the rear.
Tom B.
Scott Dorsey
>I also have a 622B that I bought out of Alpha Recording Studio here in
>Richmond, VA back in the mid 70's. Mine still works but the pots are
>scratchy sounding. I have never been able to figure out how to clean
>them. Do you have any suggestions as to how to get rid of the dirt in
>the pots? And yes mine is stereo blue front with grey knobs. Screw
>post balanced terminals on the rear.
Bring it over. The top and back panels come off, and you squirt some
Cailube into the pots, which are open types.
It's much harder to deal with the sealed pots like A-B Type Js.
I do worry about the faders on the 672 and 674, though, which seem to get
a lot stiffer when Cailube is used.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."
Robert Orban
says...
>
>Greetings,
>
>Wondering if anybody can tell me the differences between the old Orban
>621B parametric Eq and the 622B. Thanks in advance for the info.
The 621 was our first parametric design. It used a Wien bridge filter with
variable feedback to adjust the "Q." They were designed for external power
supplies, because I thought that a lot of them would go into console retrofits
and would run on one big power supply. This turned out to be far less true
than I had hoped :-). So we eventually manufactured a supply for them (the 85A
if memory serves).
The 622 was a complete redesign. It used a fairly tricky filter based on an
allpass network with variable feedback. It added in/out switches for each
band, and (finally!) had an internal power supply.
Both of these used 70's-era opamps and had a couple of tantalums in the
circuit path, so they are open to modification with better sounding caps (or
none at all; just short out the caps and tolerate small DC offsets) and up to
date opamps. (Be careful if you replace the opamps in the 622's parametric
filters; you can get oscillations if you replace the amplifiers with amps of
significantly higher bandwidth or lower phase margin.)
After the 622 was discontinued, there was the Orban 642, which used better
opamps and DC servos instead of caps. It added 18dB/octave sweepable HP
filters, 12dB/octave sweepable lowpass filters, and a frequency vernier
control that helped the operator center the filter on the desired frequency
when narrowband notches were used. The 642 was a bit pricey for its time
(although cheap by today's standards for higher end EQs!) so they're quite a
bit rarer than the 621s and 622s.