Coda CP Phono and Line Preamplifier - Manual (Page 6)

5 LOADING SETUP
Caution: The CP contains dangerous high voltages during operation, and except for
the loading settings has no user servicable parts inside. Except when adjusting the
loading you should never open the preamplifier. Before opening the CP ensure that
the AC line cord is completely disconnected.
The CPs phono input stage has adjustable loading parameters. The loading switches
are a red DIP switch block located on the printed circuit board inside the preamplifier
near the balanced input jacks.
To open the CP, use a hex wrench to remove the bolts retaining the top cover. Check
the size of your wrench before beginning. An undersized wrench will strip the heads of
the fasteners. Be sure to set the cover top-side up when removed to avoid scratching
the finish.
The DIP block adjusts both loading capacitance and resistance. The switches are set in
stereo pairs, e.g. 1 & 8 to add 1000 PF to both channels, 2 & 7 to add 200 PF, etc.
The components are switched in parallel with the built-in values of 47k Ohms and 50pF.
The final capacitance is the sum of 20pF and the two capacitor settings. The final resis-
tance is as follows:
1/Rtotal = (1/47000)+(1/R1)+(1/R2)
The two slide switches to either side of the DIP block add 20 dB of gain to each chan-
nel. By default they are disabled.
If you have any questions about adjusting the CP you should contact Coda Technolo-
gies at the address and phone number on the rear of this manual.
100 Ohms
20 dB 20 dB
1000 Ohms
200 PF
1000 PF
100 Ohms
1000 Ohms
200 PF
1000 PF