Tube Preamplifier Schematic 6DJ8 / ECC88 SRPP

This is one of many possible variations for a Symmetrical SRPP Preamplifier based around the 6DJ8 / ECC88 family of tubes. The SRPP circuit has also been referred to as a SEPP, Totem Pole, Mu Follower, Mu amplifier and Cascoded Cathode Follower. The original name for this circuit is a Balanced Direct and Alternating Current Amplifier (Maurice Artzt, Radio Corporation of America, February 9, 1943, Patent 2310342).

6DJ8 / ECC88 SRPP Tube Preamplifier Schematic

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Tube Preamplifier 5687 Led Biased Circuit

The power supply uses one RCA-83 mercury rectifier. An Omron timer is used to delay the B+ in order to allow the rectifier to warm up. The last 2 RC sections (3k6, 220uF, 3k9, 10uF) are separate for each channel, but in future I plan to remove that and use a CCS for each channel instead. The 10uF capacitor is polystyrene. Yes, those are 50H chokes!

The RCA-83 rectifier uses 5VAC for the filaments. The heaters for the 5687 tubes are provided from a full bridge of MUR860 diodes, followed by 5 x 10,000uF Elna caps. 830mA of current regulation is supplied using a LM317 regulator and a 1R5 resistor between ADJ and VOUT pins. Votlage to the tubes is about 11.5V, so I am actually running starved filaments.

The preamplifier uses the double section of a 5687 tube for each channel, with each section using it's own grid stopper (220R) and it's own pair of green LED for a 4V bias. The double section is used so as to lower the effective tube impedance, resulting in better compatibility with the Tamura A4717 5k output transformers. The 5687 tubes are operated at 115V, -4V and 25mA, which is one of the more linear regions for a 5687. Initially, I tried AC for the filaments and the result was far too much hum, so DC is used for the heaters. The schematic of the preamplifier section is shown in Figure 01.

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Stereo Gain Audio Trim Control Circuit

Audio Gain Control With Digital Potentiometers

Stereo Gain Audio Trim Control Circuit

This circuit using the MAX5160L digital pot in a divider chain supplying the MAX4252 op amp with some positive feedback in addition to the usual negative feedback via the 100K and 50K resistors. The gain of this circuit can be shown to be:

AV = (1-Kn)/(Kp-Kn)

where Kn is the negative feedback fraction, Kp the positive feedback fractions (for the example in Figure 4, Kn = 100K/(100K + 50K) or 2/3, and Kp is variable).

When the MAX5160L wiper is positioned at the VREF terminal, the gain of the circuit is -0.5V/V, as there is no positive feedback contribution. When the wiper is at mid scale, Kp = 0.5, and the gain is now -2V/V. Hence, by using those 17 positions between VREF and midscale the gain can be varied over a ±6dB range. The 15 unused positions have been traded off for repeatability, as the gain value does not depend upon the digital pot resistance tolerance, as did the circuit of Figure 1. The gain tolerance is now only limited by the ±1% 100K/50K resistors, and the INL/DNL error of the MAX5160L (±4.6% max.).

An interesting point to note, the limit for stability in this circuit is reached when Kp ≥ 2/3, when the positive feedback fraction meets or exceeds the negative. The host processor controlling the MAX5160L should therefore prevent this situation occurring.

The circuit in Figure 5 shows an obvious appraoch to a 'traditional' style volume control using digital pots. All codes are valid, with settings ranging from 0dB to full attenuation. Table 1 shows the calculated attenuations based on the MAX5160L's 32 steps.

Via

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IC TDA7294 120 Watt Audio Power Amplifier Circuit

IC TDA7294 120 Watt Audio Power Amplifier Circuit

Amplifer with IC number TDA7293 for process sound system. This amplifer was have the input for a radio, TV, stereo or other line level device. It also has a phono input for a record player, guitar, microphone or other un-amplified source. With the addition of a low pass filter at the input, it makes a great amp for a small subwoofer.

Parts

R : 660 Ohm 1/4 W Resistor = 2 pcs.
R : 22K 1/4 W Resistor = 5 pcs.
R : 10K 1/4 W Resistor = 1 pcs.
R : 30K 1/4 W Resistor = 1 pcs.
C : 2200uF 35V Electrolytic Capacitor = 2 pcs.
C : 0.22uF Capacitor = 2 pcs.
C : 22uF Capacitor = 4 pcs.
C : 0.45uF Capacitor = 2 pcs.
U1,2 : TDA7294 100W DMOS AUDIO AMPLIFIER WITH MUTE/ST-BY

T1 : 50V Center Tapped 5 Amp Transformer
S1 : SPST 3 Amp Switch
S2 : DPDT Switch
F1 : 2 Amp Fuse
SPKR1 : 8 Ohm 120W Speaker
MISC : Case, Knobs, Line Cord, Binding Posts Or Phono Plugs (For Input And Output), Heatsinks For Q1 And Q2

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300 Watt MOSFET Audio Power Amplifier

300 Watt MOSFET Audio Power Amplifier

I will share my experience with the BUZ902DP with other fans to share my passion for this minimalist perfection.I amplifier for the durable, easy to use, while the high fidelity to the original sound source and advise the partnership, this amplifier with other products of excellent quality.
When I began the design of this amp, my goal was to make a product better suited for the reproduction of complex music and voice. Although I emphasize the high electrical properties, the most important requirement is to create a superior sound, vivid images and superb spatial aural clarity.
Although the average level of listening is usually less than 10 watts, my design concept was to an amplifier with plenty of reserves, but the deviation is for Class A, at the height of the audience of cross-over distortion at a very low level.
There is no place in the pathway, enhances the precision of the tonal characteristics of instruments and voices clearly.
The BUZ902DP is virtually zero phase distortion over the audio range resolution is perfect and completely color the sound.

Amplifier Specification:
Maximum Output: 240 watts rms into 8 Ohms, 380 watts rms into 4 Ohms
Audio Frequency Linearity: 20 Hz – 20 kHz (+0, -0.2 dB)
Closed Loop Gain: 32 dB
Hum and Noise: -90 dB (input short circuit)
Output Offset Voltage: >13 mV (input short circuit)
Phase Linearity: > 13 0 (10 Hz – 20 kHz)
Harmonic Distortion: > 0.007% at rated power
IM Distortion: > .009% at maximum power

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Car audio BCL 20W TDA2005 Amplifier

TDA2005 Amplifier Car audio BCL 20W Scheme Circuit

PCB TDA2005 Amplifier Car audio BCL 20W

circuit TDA2005 Amplifier Car audio BCL 20W

The Circuit TDA2005 Amplifier for Car audio BCL 20W.
Volt supply 11V to 14V, Power output 10W+10W#, for Speaker 2-8 ohm. This is the best car audio amplifier.

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SKEMA RANGKAIAN VOLUME DIGITAL

This series is the volume of the digital amplifier that is used on or tone control. This series using ic type DS1669 Digital Pot IC specifically for this match volume.rangkaian settings used at the middle-class amplifier that small powerless under 50 watts.

volum11

components: C1 = 0.1uf Ceramic, IC = IC DS1669 Digital Pot, S1 / S2 = digital swicth

Or you can use the series to this one:

volum2

The Work: The digital volume control IC uses 9. Required to operate the series voltage regulator is 12 Volt. IC1 (555) is very good to work as a flip-flop. Frequensi or period can be determined with memilh value of resistor R44, R45 is combined with a capacitor C6. In this series has a 0.3 second period.

IC2 is used to increase or decrease the calculation. In the series of this mode is used to raise up and down mode is used to decrease the volume. While IC4 and IC3 has a 16-channel, analogue multiplexers, while working as an analog switch. IC3 is used as in the series of level indicator while IC4 is used as potensiometer.

After the next power in the on-kan, and the switch S1 is pressed to reset. When the switch S2 is pressed, the IC2 and the balance in the form of output ditanggapi legs B, C, and D in CMOS IC2. Output B, C and D control line inputs IC2 and IC3, and the chosen one, the output 16-channel, by turning on the analogue.

In this series, IC4 is used as potensiometer that is connected to the resistor 15 (R9 to R23) each of the 16 input pins and resistor / capacitor combination with C2, C3 and R7 to the output. Switch S2 is used to raise and switch S3 is used to decrease the volume.

Electrolyte capacitor of 1uF (C4) is used utnuk prevent the occurrence of noise. While the R8 and the resistor R6 is used to prevent tension on the half-supply voltage in order to avoid distortion of the audio signal coming from the preamplifier. Meanwhile, capacitor C2, C3 and resistor R7 is provided to filter the audio. Happy work, hopefully successfully.

COMPONENT LIST :

R1, 2, 3, 4	: 560R	R16	: 1,5K	R45	: 150K
R5	: 680R	R17	: 3,3K	C1	: 0,01uF
R6, 8	: 100K	R18	: 5,6K	C2, 3	: 100nF
R7	: 1M	R19	: 8,2K	C4	: 1uF/50V
R9	: 10R	R20	: 15K	C5	: 100nF
R10	: 12R	R21	: 33K	IC1	: 555
R11	: 42R	R22	: 56K	IC2	: 74193
R12	: 100R	R23	: 1,5M	IC3	: CD4067
R13	: 220R	R24…R39	: 560R	IC4	: CD4067
R14	: 470R	R40..R43	: 4,7K	IC5	: 7805
R15	: 820R	R44	: 330K	IC6 N1-N4)	: 7407

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Audio Amplifier 70 Watt MOSFET

Distortion measurement.
Harmonic distortion, measured at 300mV rms input.
The 20Hz figures are not very accurate, maybe plus or minus 10dB.

Frequency....2nd-harmonic....3rd harmonic
20Hz............-114dB............-124dB
1kHz............-116dB............-129dB
5kHz............-107dB............-116dB
7.5kHz..........-106dB
10kHz...........-102dB

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Rangkaian Audio Power Indicator

Component List of Audio Power Indicator:

R1_____________220R 1/2W Resistor
R2,R5,R6,R8____100R 1/4W Resistors
R10,R12,R14____100R 1/4W Resistors
R3_____________220R 1/4W Resistor
R4,R7__________330R 1/2W Resistors
R9_____________560R 1/2W Resistor
R11____________820R 1/2W Resistor
R13______________1K2 1/2W Resistor

D1___________1N4004 400V 1A Diode
D2,D4,D6__BZX79C2V7 2.7V 500mW Zener Diodes
D3,D5,D7,D8,D9,D10 Red LEDs (Any dimension and shape) (See Notes)


Notes:

* The output power indicated by each LED must be doubled when 4 Ohms loads are driven.
* The circuit can be adapted to suit less powerful amplifiers by reducing the number of LEDs and related voltage dividers.
* LEDs of any dimension can be used, but rectangular shaped devices will be more suitable to be compacted in bars or columns.
* For a stereo amplifier, two identical circuits are required.

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