On Sun, Dec 30, 2018 at 11:32 AM, MoparWade wrote:
Here's part of what the MSR from July 1991 said:
TEK 760 Audio Monitor Status
ThiS MSR clarifies recent activity regarding the TEK 760 product family. Specifically:
760A. what, why,,where & how (& how much)
760 limited availability, upgrade path
760D, 760N status
The 760A is en improved version of the 760 audio monitor. Most significant is our
modification of the ballistics of the PPM to conform to the proposed (and soon-to-be
formalized) revisions of IEEE std 152-1953 Recommended practice for Volume
Measurements of Electrical Speech and Program Waves. This revision incorporates
EBU Standard 2305-E. In layman's terms, minor changes to the ballistics makes the
760A compatible with major international standards.
We've also modified the "EXPAND SCALE" feature of the 760A to make it easier to perform
gain adjustments on audio signals. The former "SCALE/10" button increased the
resolution of the PPM scale by 10X but was centered @ the 0 dB point - great if your
using a VU meter (whose house reference reading should read 0 dB) but not so terrific
for a PPM since its house reference reading should read -8 dB. The new "EXPAND
SCALE" button increases the resolution by 4X and centers the reading @ -8 dB.
Minor changes have also been made to the SELECT function. On the 760 a user was
able to select internally derived SUM or DIFF displays. These were labelled "ADD 6 db"
probably not the best way to indicate that the amplitudes of these displays were actually
half of their true amplitudes. On the 760A a user may now select L+R/2 or L-R/2 and
more clearly understand that the amplitudes are halved.
All other features of this popular Audio Monitor are preserved in the Tektronix 760A
Stereo Audio Monitor. The 760A is a revision of the 760 only. 760D & 760N models are
unaffected by these revisions.
The 760 model has been placed on limited availability status.