Monday, April 15, 2013

MT-2 Boss Metal Zone Schematic

Technical specification:
    Input Impedance: 1MΩ
    Output Impedance: 1kΩ
    Recommended Load Impedance: 10kΩ or greater
    Equivalent Input Noise Level: -110 dBu or less (IHF-A, Typ.)
    Power Supply: 9V Battery or PSA-Series AC Adaptor
    Current Draw: 20mA (DC 9V)

Overdrive Effect

Ibanez Tube Screamer TS-9
Boss Super Overdrive SD-1

Marshall Pedals: Blues Breaker, Drive Master & Shred Master
Marshall Blues Breaker
Marshall Drive Master

Marshall Shred Master

Sunday, April 14, 2013

Fender Blackface Preamp

Parts List : 

P1,P2                          220K  Linear Potentiometers (or 250K)
P3                               10K  Linear Potentiometer
P4                               1M  Log. Potentiometer
R1                               1M  1/4W Resistor
R2,R3                         68K  1/4W Resistors
R4,R5,R6,R7,R8        100K  1/4W Resistors
C1,C7                         47µF  25V Electrolytic Capacitors
C2                               220pF  63V Ceramic or Polystyrene Capacitor (or 250pF)
C3                               100nF  63V Polyester Capacitor
C4                               47nF  63V Polyester Capacitor
C5                               100µF  35-50V Electrolytic Capacitor
C6                               120pF  63V Ceramic or Polystyrene Capacitor
C8                               47nF  63V Polyester Capacitor
Q1,Q2,Q3,Q4             2N3819  General-purpose N-Channel FETs
J1,J2                            6.3mm  Mono Jack sockets
SW1                            SPST Toggle or Slide Switch

Wednesday, April 10, 2013

Hampton Moving Coil Preamplifier

 Components List  :
R1-5= 100ohm 1% 1/4W
R2-6= 150ohm 1% 1/4W
R3-7= 33ohm 1% 1/4W
R4-8= 12ohm 1% 1/4W
R9...12= 47Kohm 2W
R13-14=1Mohm 1% 1/4W
C1-2= 1uF 250V MKT
V1-2= ECC88 - 6DJ8
S1-2= DIL Switch
J1...4= RCA Jack
Some of the services today preamps using vacuum tubes still in their ability to deliver high-quality audio and unique colors when used with amplifiers. The vacuum tube preamplifier used in the musical instrument amplifier with tone control circuits In this connection it is of the coil wire applications, the ability to obtain high-quality signals and Equalization

Conventional MC-MM Pre Amplifier

The circuit is (more or less) conventional, with a common emitter stage constant current source modulation. When the series is a mirror that is reproduced for both positive and negative supply voltage. Net output voltage again a low DC offset, but may be slightly higher than previous models, because of the lack of power to 0V DC bias to obtain a correct output.

Benefit from a 2.2k resistor from the collector of the output device (parallel, 1.1k) and a 15 ohm resistor (MC or moving coil position) optionally controlled in series with a 150 ohm (MM Moving Magnet or position).

This results in a theoretical advantage 74 (37dB) in the MC position or 7.6 (17.6 dB) for the MM setting. In practice, one can expect very little profit to be less than these figures, especially for MC setting.

I can not comment on the relative noise performance of both pre-amp, but because they are both on a design by renowned audio designer, I would hope that the noise either be a problem with the circuit.

Monday, February 4, 2013

Marshall JCM900 Preamp Schematic

I did not include technical data for this preamp, it's just a scheme to guide repair. May be useful for those who have a Marshall JCM900 guitar preamp .

Friday, February 1, 2013

10w 6L6 Push Pull Amplifier


Frequency Response :
15-65Kc (-3dB), 1Kc input, at 3W RMS output across 16 ohms.

Power :
10W RMS for 700mV RMS input, with a THD+Noise of 0.29%

Tube Complement :
1x 6J5 (input), 1x 6SN7 (differential phase inverter), 2x 6L6GC (output), 1x 5R4GYB (rectifier)

The Output Transformer :
The Hammond 1650K is a 7 lb. oversized monster for our current and wattage demands, but it has a 3.4k primary.

Saturday, January 26, 2013

High Quality Vacuum Tube Headphone Amplifier

Theres no transformer in output, it only need coupling capacitor in the signal path is the output cap. A relay circuit was used to provide muting and a time delay was used to keep the output muted during warm-up in order to protect the headphones from the high voltages that would otherwise be present at the output of the amplifier.

A separate chassis was used for the power supply to keep noise levels as low as possible. Selection of input tubes (6SN7s) for low noise is important in order to realize the full capability of this circuit. Since I already have a regulated source of 12 volts DC, I intend to modify this amplifier in the future to use 12SX7s.

The power supply is a fairly conventional design using a 6550a as a series pass regulator and a zener string to set the operating voltage.

The amplifier circuit is a 6SN7 run in grounded cathode mode and is self-biased using an un-bypassed cathode resistor. The input stage is direct coupled to a 6CA7 that is used as a cathode follower. The output from the 6CA7 is coupled to the headphones using a 47uF capacitor, providing extended bass response. The output capacitors are bypassed with 1uf and .01uF polystyrene capacitors. An Alps 'Black Beauty' volume control is used to help preserver sonics and easily allows adjustment at low gain levels with adequate tracking between the two channels.

A switchable cross-feed circuit is present at the input of the amplifier to be used to help correct imaging problems, if desired.

Schematic of Hadphone Amplifier

Power Supply of Headphone Amplifier

Thursday, January 24, 2013

Class A Single end 2SK1058 Amplifier

Sure there has to be single active component in an amp in order to get the gain to be called an AMPLIFIER. That's a simple amplifier as a single end tube amplifier. A single end vacuum tube Amp need a resistor or two and an output transformer. So I design a FET amp around the same simplicity of design. One audio grade MOSFET, a couple of resistors and capacitors and a heavy duty well filtered power supply. The schematic for the amplifier section is shown in Figure 1.

The amplifier is built around the Hitachi 2SK1058 N-Channel MOSFET. A schematic and pin diagram for the 2SK1058 is shown in Figure 2. I used Sprague capacitors for the input coupling and a large electrolytic on the output with a 10µF polyester bypass capacitor. The four 10W non-inductive wire wound resistors act as the load. The four resistors are 15ohm and 10W each which I wired two in series for 30 ohms and then the two sets of 30 ohms are wired in parallel to give a total resistance of 15 ohms. These get extremely hot and burn about 30W at idle. Yes, Class-A amplification is very inefficient. I burn over 20 Watts to get only about 4.8 audio Watts per channel! The heatsink I used is rated at 0.784 °C/W.

2SK1058 Pin Out

Schematic 2SK1058 Amplifier

Power Supply of  2SK1058 Amplifier

Stereo 2SK1058 Amplifier Module

Thursday, January 10, 2013

300B Single End Vacuum Tube Amplifier

Current (new) production 300B tubes like the Electro-Harmonix 300B and the JJ 300B sound wonderful at a fraction of the Western Electric 300B price. A direct coupled driver stage and a low mu triode array are the specific reasons why this design works so well. Good output transformers are the key to good performance. Magnequest FS-030 or XE-60S are good choices.

The schematic for the 300B Single-Ended Vacuum Tube Amplifier is shown below. Using audio output transformers with a primary impedance of about 3000 to 3500 ohms you can expect about 8W of output with at about 2.5% THD. 

Saturday, January 5, 2013

Single End Tube Power Amplifier

  • This a simple Tube Amplifier with singgle end Tube.
  • The power supply use 4xIN4007 Silicon Diode.
  • The filament supply is regulated at 6.3V using a LT1085 voltage regulator.
The schematic taken from the book "Build your own Audio Valve Amplifiers" by Rainer zur Linde. 

Wednesday, January 2, 2013

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.