AN6077 INTERSIL [Intersil Corporation], AN6077 Datasheet - Page 10

• Manufacturer Part Number: AN6077
• Description: An IC Operational Transconductance Amplifier With Power Capability
• Manufacturer: INTERSIL [Intersil Corporation]

The unaffected portion of the gain (A
control and A
To make the controls work symmetrically, the low and high
frequency break points must be equal for both boost and cut.
Thus:
since R
and
since
To make the controls work in the circuit of Figure 14, breaks
were set at 1000Hz:
for the base control
and for the treble control
Response and Control Rotation
In a practical design, it is desirable to make “flat” response
correspond to the 50% rotation position of the control, and to
have an aural sensation of smooth variation of response on
either side of the mechanical center. It is easy to show that
the “flat” position of the bass control occurs when the wiper
arm is advanced to 91% of its total resistance. The
amplitude response of the treble control is, however, never
completely “flat”; a computer was used to generate response
curves as controls were varied.
Figure B3 is a plot of the response with bass and treble tone
controls combined at various settings of both controls. The
values shown are the practical ones used in the actual
design. Figure B4 shows the information of Figure B3
replotted as a function of electrical rotation. The ideal taper
for each control would be the complement of the 100Hz plot
for the bass control and the 10kHz response for the treble
control. The mechanical center should occur at the
crossover point in each case.
and C
Bass Control:
Treble Control: R
=
-------------------- - C
R
R
1
1
R
+
1
R
C
2
R
R
2
C
3
1
3
2
3
=
100C
=
R
1
C
----------------------------------------- -
C
----------------------------------------- -
2
LOW
R
+
1
R
-------------------- -
R
2
+ R
R
1
C
R
R
1
1
1
2
3
+
1
---------------------------------------------------------------
2
3
+
+
,
C
R
for the treble control) is 11 in each case.
R
3
R
C
R
R
R
1
, C
2
2
1
2
2
C
1
2
0.1C
+
+
+
4
+
=
---------------------------------------------------------------
R
R
R
+
C
R
C
2
C
3
2
3
C
1
1
2
1
R
3
= 10C
C
R
3
4-10
+
1
=
and C
C
4
3
C
C
4
+
C
---------------------- -
C
=
3
R
4
+
C
2
1
2
=
------------------------- -
2
1
C
2
R
+
1
+
C
1
2
------------------------- -
2
C
R
=
C
4
R
4
1
3
1000
3
+
HIGH
3
10C
1
C
1000
1
C
4
,
for the bass
2
R
1
=
Application Note 6077
9R
2
FIGURE B2. CUT AND BOOST BASS AND TREBLE CONTROLS
FIGURE B3. A PLOT OF THE RESPONSE OF THE CIRCUIT OF
45
40
35
30
25
20
15
10
5
0
10
Q = 1.0
Q = 0.99
Q = 0.98
Q = 0.96
Q =0.914
Q = 0.85
68
THAT HAVE THE CHARACTERISTICS OF THE
CIRCUITS IN FIGURE B1
FIGURE B2 (B). TREBLE CONTROL
FIGURE 14 WITH BASS AND TREBLE TONE
CONTROLS COMBINED AT VARIOUS SETTINGS
OF BOTH CONTROLS
R
C
FIGURE B2 (A). BASS CONTROL
0.12 F
2
1
0.001 F
Q = 0
100
1K
CW
CW
1.8K
Q
Q = 0.75
Q = 0.5
Q = 0.2
0.2
C
R
C
F
P
FREQUENCY (Hz)
100K
2
2
2
15K
0.02
P = 0.98
P = 0.96
F
R
R
0.001
1000
3
1
E
F
S
P = 0.92
P = 0.05
C
C
P = 0.8
P = 0.5
P = 0.3
P = 0.1
3
1
CCW
CCW
10K
0.01 F
+
-
820
+
-
-
+
E
R
C
O
1
4
10K
P = 0.99
P = 1.0
P = 0
100K