Harmon Kardon Tone Control Circuit

Tube : 12AU7/12AX7

Frequency Response :

The vertical scale is linear in dB from minus 9 to plus 18 with marks every 3 dB. 

Frequency is from 10 cycles to 100 kc on a log scale. 

There are 5 curves making the shape of an hourglass turned on its side. 

• The top curve starts at 10 cycles and plus 15 dB. At 50 cycles it is at 13 dB and falls until it reaches a minimum at 850 cycles and 1.5 dB. It rises again reaching 8 dB at 10 kc and topping out at 9 dB at 25 kc. It falls to 7.5 dB at 100 kc. 
• The second curve starts out at 10 cycles and 6.5 dB, 50 cycles, 5 dB, 100, 3 dB, 200 cycles, 1 dB 400 cycles 0 dB. At 1 kc it is at 1 dB, at 2 kc, 2 dB and 10 kc 2.5 dB. Past 20 kc it starts to decline and is at 0 dB at 100 kc. 
• The third curve is a straight line at just a scoash over 0 dB. 
• The fourth curve starts at minus 4.5 dB at 10 cycles. It is minus 4 at 50 cycles, and has risen to 0 dB at 300 cycles. It rises about half a dB above zero and crosses zero again at 1 kc. It is at minus 1.5 dB at 10 kc and minus 2 dB at 100 kc. 
• The fifth curve starts at minus 8.5 dB at 10 cycles and is at minus 8 dB at 50 cycles. It is at minus 3 dB at about 250 cycles and rises to a maximum of minus 0.5 dB at 850 cycles. It falls to minus 3.5 dB at 10 kc and minus 4 dB at 100 kc. End verbal description.

Hi-Fi Audio Amplifiers with TL072 Preamp Circuit

The amplifier is very easy to get on the board, and an innovative tone defeat. Instead of completely disabling the sound system, the massive de-sensitized, and they defeated a maximum range. This can be increased if desired, you can have two tone controls, the lifting of 10 dB and a cut and the other with a little help and very subtle 3dB cut - it is quite (surprisingly) a very small adjustment to how you need for day-to-day hearing.

Otherwise, the design is fairly standard, with a great advantage over other models that require virtually no cable. Download the source you want - I suggest you put a switch on the back of the cabinet, and an extension of the tree with the tree in front. This leads to a minimum of wiring and reduces the crosstalk from other active inputs.

Description of the circuit

The input stage is shown with a gain of 2 times (-6 dB), configure, and also acts as a buffer for the tone control. The tone control is a basic form Baxandall, but the addition of R117, 118 and 119 provides the flexibility and ease of reconfiguration, which is the traditional layout.

I have not seen before, this technique is used). As it is 100k, which limits the number of tonal control at a reasonable price + /-10dB. To increase further in section, R119 (R219 and receive) can be omitted. Conversely, reducing the value of a small area is also about 6 dB at 20 Hz and 20 kHz with 7.5dB at 22K.

Audio system (and overall) performance is shown in Figure 2 (in increments of 10% of the pot), and it seems that the midrange is not affected. This is contrary to most of the drawings, in which the control is aligned to 1 kHz, and is very audible in the media. For those who want to use the tone controls, I would suggest that both, with no tone controls are designed and in harmony with reality, minimalist design.