GHR Audio

-

-

The Bell System Technical Journal 1951-01: Vol 30 Iss 1

sim_att-technical-journal_1951-01_30_1_0006.jpg
sim_att-technical-journal_1951-01_30_1_0007.jpg
sim_att-technical-journal_1951-01_30_1_0008.jpg
sim_att-technical-journal_1951-01_30_1_0009.jpg
sim_att-technical-journal_1951-01_30_1 ...

Bell Laboratories Record 1937 June

sim_record-at-t-bell-laboratories_1937-06_15_10_0006.jpg
sim_record-at-t-bell-laboratories_1937-06_15_10_0007.jpg
sim_record-at-t-bell-laboratories_1937-06_15_10_0008.jpg
sim_record-at-t-bell-laboratories_1937-06_15_10_0009.jpg
sim_record-at-t-bell ...

Bell Lab Record 1934 December

sim_record-at-t-bell-laboratories_1934-12_13_4_0001.jpg
sim_record-at-t-bell-laboratories_1934-12_13_4_0002.jpg
sim_record-at-t-bell-laboratories_1934-12_13_4_0003.jpg
sim_record-at-t-bell-laboratories_1934-12_13_4_0004.jpg
sim_record-at-t-bell-laboratories ...

The Bell System Technical Journal July 1934

Script wrote: Thu Sep 11, 2025 11:02 am R22 1/4 W, got it. Thank you.

1/2 W

Don't use super bright LEDs on the sidechain! Use LEDs with luminous intensity of 300 mcd or less. I used 80 mcd LEDs.

D1 = 4007x

+/- 18V will work too and 166 mA should be enough or go with DCWN06A-15.

1/4W should be fine on the sidechain, except use 1/2W on R22.

I didn't have the zener yet when I took the picture and I added it later. It will work without the zener, but it's better if it is there.

Don't use the old mastering modifications with this new version!

In the new version sidechain already has 1 dB steps and high-pass filter. The output trimmers can be added if the quasi-floating output is disabled. The 0.5 dB gain steps can be added.