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

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

Application 

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.

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 .

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.

Octave Equalizer

This Equalizer will satisfy your wishes about your sound appetizing, you can plug in your audio device or can be used as a guitar tone control. 

If you don't want your audio device looks much potensiometer control, you can change the potensiometers with trimpot and it' will hided in the equalizer box.

Schematic of Octave Equalizer

Solder side of Octave Equalizer PCB

Component Side of Octave Equalizer PCB

 Parts List :

Resistor:
R1 = 68 KOhm
R2,R6,R11,R15,R16,R17,R18,1R19,R20,R21,R22 = 1 KOhm
R3 = 6,8 KOhm
 R4,R7,R8,R9,R12,R13 =3,9 KOhm
R5,R1O = 12 KOhm
R14 = 220 KOhm
R23,R24,R25,R26,R27,R28,R29,R3O = 82 KOhm
P1...P8 = Potensiometer 10 KOhm linier

Capasitor:
C1 = 820 nF
C2,C5,C6,C9,C36 = 820 pF
C3,C7 =   100 uF/4 V
C4,C8,C24,C30 = 4,7 nF
C10 = 470 nF
C11 = 1uF
C12,C15 =  270 nF
C13,C16,C2O = 47 nF
C14,C23 =  15 nF
C17 =   12 nF
C18,C21 = 3,3 nF
C19 = 33 nF
C22 = 560 pF
C25,C34 = 1 nF
C26 = 39 pF
C27 =  560 nF
C28 =  82 nF
C29 = 27 nF
C31 = 120  nF
C32,C35 = 39 nF
C33 = 6,8 nF
C37 = 1,5 nF
C38,C41 = 470 pF  
C39 = 10 nF
C40 = 3,9 nF
C42 =  15 pF
C43,C44,C45,C46,C47,C48 = IO0 nF MKM
C49,C50 = 10 uF/25 V

Semikonduktors:
T1,T2,T5 = BC 549C/BC 550C
T3,T4,T6,T7 = BC 559C/BC 560C
IC1,IC2 = TL 084

High Quality Preamp with Tone Control

Spesification :

• Sensitivity input to output 500 mVef / with load resistor 10 kOhm:

          MD: 2,6 mVef/50 KOhm (@ 1 kHz)
          Tuner 130 mVef/50KOhm
          Tape Player: 130 mVef/50KOhm

• Output Impedance

          1,2 KQ

• Balance Control

         (at 10 KOhm Load) : +3,3 dB
         (Loadless) : +2,3 dB

• Tone Control

         +/- 10 dB at 50 Hz (Low)
         +\- 10 dB pada 10 kHz (High)

• Sinyal/Noise (thd 500 mV€f):

          MD: 65 dB
          Tuner/Tape : 75 dB

• MD Max Input Voltage  at 1 kHz : 200 mvef

          (reflection characteristics of the RIAA)

Schematic

Pcb1

  

Pcb2

Parts  List :

Resistor :
R1,R1',R2,R2',R8,R8',R10,R10' = 10 KOhm
R3,R3' = 270 Ohm
R4,R4' = 560 Ohm
R5,R5' = 10 KOhm
R6,R6' = 120 KOhm
R7,R7' = 220 KOhm
R9,R9' = 22 KOhm
R11,R11'.R12,R12' = 82 KOhm
R13,R13',R14,R14',R17,R17' = 2,2 KOhm
R15,R15',R16,R16' = 47 KOhm
R18,R18',R19,R19' = 100 Ohm
P1/P1' = 100 KOhm log. stereo
P2/P2',P4/P4' = 10 KOhm lin. stereo
P3/P3' = 4,7 KOhm(5KOhm)  lin. stereo

Capasitor :
C1,C1’ = 120 nF
C2,C2' = 47 uF/6,3 V Tantalum
C3,C3',C4,C4',C10,C10',C11,C11' = 15 nF
C5,C5' = 27 nF
C6,C6',C7,C7',C8,C8',C9,C9',C12,C12',C13,C13',C22,C22',C23,C23' = 10 uF/35 V tantalum
C14,C15 = 220 uF/25 V
C16,C17 = 330 nF
C18,C19,C20,C20',C21,C21',C24,C24',C25,C25' = 100 nF
C26,C26' = 22 pF
C27,C28 = 1 uF/35 V tantalum

Semi conductor :
IC1,IC1' = TDA 1034BN, NE 5534N (Philips/Signetics)
C2,IC;',IC;,IC;' = TDA 1054B, NE 5534 (Philips/Signetics)
IC4 = MC 78L15CP (10%) or MC 78L15A CP
           (5%) (Motorola)
IC5 = MC 79L15CP (10%) or MC 79L15A CP
           (5%) (Motorola)
B1   = B40C500

Other Parts :
S1/S1',S2/S2' = bipolar Switch
S3 = On/Off Switch
Tr1 = 2 x 15 V 100 mA Transformator
F1 = 100 mA Slow Fuse

High Quality Head Pre-Amp

This routine reveals a dc-coupled, two-head music preamp using an LM1897. The routine features are: a GBW of 76 dB at 20 kHz, an S/N rate of 62 dB (CCIR/ARM), frame distortions 0.03% at 1kHz, power-supply denial higher than 95 dB, route separating of60 dB, and a common turn-on wait of 0.4 s.

Super Low Noise Phono Preamp

Schematic

PCB Lay Out

Parts List :

Resistor :
R1 = 56 Kohm/1%
R2...R9 : 68 Kohm/1%
R1O...R11 : 4,7 Kohm/1%
R1O...R11 : 4,7 Kohm/1%
R12, R15 = 1,8 Kohm/1%
R13,R19 = 150 ohm/1%
R14 = 270 ohm/1%
R15 = 150 Kohm/1%
R16,R2O : Kohm/1%
R17 = 12 Kohm/1%

Capasitor :
C1 = 4,7 pF
C2,C3,C9, C10,C11,C13 = 4,7 uF/16 V, tantalum
C4,C6 = 3,3 nF/2%
C5,C7 = 10 nF/2%
C8 = 470 nF
C12,C14 = 1 pF/35 V, tantalum

Semikonduktor :
T1...T8,T17,T19 = BC 550C, BC 414C
T9...T15,T18,T20 = BC 560C, BC 416C
IC1 = 78L15
IC2 = 79L15


Specification :
input sensitivity (Output : 200 mV):                     2,5 mV/1 kHz
input impedance:                                                49 KQ/280 pF
Maximum input voltage (at 1 kHz):                     110 mV
Distortion Factor (Output 200 mV);
                                                   100 Hz:          < 0,001%
                                                   1 kHz:            < 0,001%
                                                   20 kHz:          < 0,001%
Over Load Distortion at +32 dB (output 8,4 V)
                                                   100 Hz:          < 0,016%
                                                   1 kHz:            <  0,01%
                                                   20 kHz:          <  0,01%
Deviation from the characteristic IEC:
                    C4...C7  with 5% tolerance:          < 10,55 dB
                                  with 2% tolerance:           < 10,25 dB
Frequency response
                     (C4...C7  at 5% tolerance):          0 Hz...40 kHz
                                                                         and 10,55 dB
Comparison of signal-noise                                > 86 dB

JFET Preamp By Albert Kreuzer

Schematic

PCB component side

PCB solder side

Pre amplifier with some level use JFET (BF245). This preamp can make sound like a tube preamp. Why use Jfet, cause it has like tbe caracteristc with lower overload than tube (not like tube real).

High Quality Pre-Amp

This is a very good preamp circuit in terms of sound quality, s / n ratio and can be used for general purposes input.

Without Tone Control?

Hmmmm .... yes for those who like HI-FI ... why should you use tone control that will only damage the authenticity of the sound reproduction.

Stereo Tone Control Circuit with IC NE5532

Features

•     Evaluation Reviews Disruption Voltage:
•     5 nV/Hz Typ at 1 kHz
•     Unity-Gain Bandwidth: 10 MHz Typ
•     Common-Mode Refusal Ratio: 100 dB Typ
•     Greater DC Present Gain: 100 V/mV Typ
•     Peak-to-Peak Result Present Move 26 V Typ
•     With VCC± = ±15 V and RL = 600
•     Greater Number Rate: 9 V/µs Typ

DESCRIPTION/ORDERING INFORMATION

The NE5532 is high-performance efficient amplifiers preparing amazing dc and ac features. They operate very low interference, higher output-drive efficiency, higher unity-gain and maximum-output-swing bandwidths, low disturbances, higher number amount, input-protection diodes, and result short-circuit security. These efficient amplifiers are paid for inner for unity-gain operate. These devices have specified highest possible possible limitations for comparative feedback interference current.

 

Pic. 1 Layout PCB

Pic.2 Schematic

Low Noise Moving Coil Phono Preamplifier

This preamplifier was designed for low stage of stage of resistance options like going rings heads (MC). The schedule uses in identical three duble transistors SSM2220 or MAT03 and by creating a diferential company keeps noice low. Linking this company before part of a OP27 amp we acquire even decreased disruption. Also the operate we use PNP rather NPN transistors is cause they have les low reliability noise. This Output must conected to Moving Magnet Preamp input.

NE5532 Moving Magnet Phono Preamp

DC to DC ripper alternatives provides a maximum possible possible power of about 36 h at an efficiency of 90%. Besides a modern FET and Schottky diode, this schedule is very well known and cost-effective elements.

This Phono Routine is very low disruption and with little distortions
S/N: about 92%
ripple: 10 mV.
max Outcome current: 1.5 A.
max going frequency: 40 kHz
voltage: 12 V.

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.

Simple Stereo Synthesizer

There are two common methods for generating a pseudo-stereo effect from a mono signal, the mono signal to both speakers play out of phase, and the use of frequency selective techniques, which usually consists of directing lower frequency signals in a single channel and higher frequency signals in the other. This circuit uses the second technique, but it can also antiphase signals that can give a better effect, especially when using headphones.

Q1 is used an emitter follower buffer stage, which provides two filter networks quagmire of its production is driven low impedance source. If they were driven directly to the input, it is quite possible that they would receive food source impedance of a few ohms or more pounds, which would be more than enough to change their properties effectively.

Both filters are formed by R4 and C3 (low pass), and C6 and R8 (step height). Wind in the price is not essential in this application and the rate of attenuation of 6 dB per octave filters simple as that RC is perfectly adequate. The-3dB point of each filter is about 800 Hz and mixed, therefore, gives an almost flat response, with significant peaks or troughs.

Q2 is connected as an emitter follower buffer stage, which ensures that there is minimum load on the low-pass filter. Q3 also ensures that there is minimum load on the high-pass filter, but this device can also serve as a phase separator. With SW2 switched to the output of the transmitter third quarter, Q3 acts effectively as an emitter follower and makes no phase inversion. With SW2 switched to exit in the third quarter of collectors, Q3, thus effectively act as a common-emitter stage with negative feedback of 100% (and a unity voltage gain) due to R11. 1t also provides a phase change of 180 °, so the two output signals are in phase opposition. A phase conditions are necessary to give a good stereo image center and use of anti-phase signals tend to give an impression of greater separation channel.

Stereo recording in an orchestra, it is normal for the violins from the left channel, with cellos and basses in the right way. Therefore, the high frequency signals are routed to the left channel and low frequency signals are routed to the right channel so that the device gives a similar effect (although this will obviously work well with the outputs connected both ways ).

Balanced Mic Preamp

The preamplifier is designed for use with dynamic (moving coil TM) microphone with an impedance of 200 Ω balanced and terminals. It's a pretty simple design, which can also be seen as an amplification stage based on a single instrument type NE5534 op amps. To get the most common mode rejection (CMR) in a balanced signal, the reasons for the division of the dividers (R1-R4-R5 and R2, respectively) to the inputs of operational amplifier must be identical. Since this can be difficult to achieve in practice, a preset potentiometer P1 is connected in series with R5. The preset allows the common mode rejection optimal.

The capacitor C1 prevents input voltage while the resistor R7 ensures the stability of the amplifier with capacitive loads.

Resistor R3 prevents the amplifier goes into oscillation when the input has been interrupted. If the microphone cable is reasonably long, R3 is not necessary, because the parasitic capacitance of the cable to ensure the stability of the amplifier. It should be noted, however, that because the R3 improve the> 70 dB CMR> 80 dB. Performance of the preamplifier is very good. THD + N (total harmonic distortion plus noise) is less than 0.1%, where the input signal is 1 mV and the impedance of 50 Ω current. Under the same conditions, the signal to noise ratio is -62.5 dB. When the values ​​of the components have been defined, the gain is 50 dB ('316). After careful adjustment P1 at 1 kHz, CMR, without R3, is 120 dB. The supply voltage is ± 15 V. The power amplifier pulls the voltage of about 5.5 mA. Note: the removal of power lines with L1, L2, C2-C5.

Digital Equalizer

The series is I do here is a series regulator Volume, Bass and Balance digital Trable (tone control). The core of this circuit is an output-type IC manufacturer Maxim MAX5406, while the IC is an audio processor that comes with the switch successfully interface for tone control setup above. The circuit diagram is as follows

 

The above scheme uses support components and this makes very little can be done with only a small matchbox, even if used all SMD components can be reduced in size to half that time I'll just give Simply design, following pic:

 

HiFi Pre-amp

This is a HiFi low noise pre amplifier schematic. Wide frequency range around 10 Hz to 100 kHz will be won by the amplifier for maximum sound quality.

Surround Sound Decoder

Presentation

The surround decoder is based on the "Hafler" principle, first discovered by David Hafler in the course of the 1970s. The original idea was to connect a pair of speakers as shown in Figure 1, for use as rear speakers in the surround setup.

It is fine as it is, but the problems are created when the main speakers are bi-amplification or transitional assistance, as it is a sign of full range output / total available for the rear speakers. There is no way to control the playback level, because it always ends up being the difference signal between left and right.

If the signal is mono, the signal on both channels is always more or less the same, and should not be starting from the rear speakers at all.

 The Original "Hafler" Surround-Sound Matrix

This circuit works by allowing the rear speakers to play only the difference signal between left and right outputs. All stereo encoded material has a certain difference between left and right (otherwise it would be mono), and this difference is that the output signal from the rear speakers.

It is important to ensure that the connection between the rear speaker terminals are unfounded negative, or they are simply in parallel with the main speakers.

Version line of passive level

So if you want to use separate amplifiers for the rear speakers, basically you can not - if you get smart. The first circuit shown in Figure 2 is completely passive, but requires that a suitable transformer. A suitable transformer means a line level, impedance of 10k units 1:1 - these are scarce, but are available after a search.

You may be able to get away with 600 units of ohms, but because the impedance needs, its performance is very common, with an extreme lack of bass (there are not enough inductance is 600 ohms transformer to operate at high impedance). Transformer is loaded to give back some of the low, but the preamp is likely to be very satisfied with the impedance. That said, I used this application to telecommunication transformers (600:600 ohm) and seem to work well.

Passive Line Level Hafler Matrix Decoder

The circuit is not a bad compromise, even if the impedances are too low to non-solid state preamp (preferably operational). Using a telephone adapter (600 Ohm), the loss is about 3 dB low frequency-3dB point around 100Hz. This varies depending on the quality of the transformer used, so experimentation is necessary. Although the 600 ohm telephone transformer are relatively easily available, some of them are quite common.

My tests were in a very good built by an Australian company called Transcap. I think I can say with some certainty that they will be reluctant to sell a single quantity. Another transformer manufacturer Midcom is very good in the U.S., but you will have the same problem with them. These manufacturers are prepared to deal with large orders from other companies, not people like you and I want ("Want a ...?") transformer. Therefore, you have to take everything you can get.

Since it is unlikely to be viable for most manufacturers, the alternative is to go active, using an ADC to perform the functions. This is described below.

The new circuit

The diagram in Figure 2 is a simple way to achieve the same (with some additional benefits) are online (ie, before the signal reaches the power amplifiers - in a bi-amp, this circuit is to be among the preamplifier and electronic crossover). The extras available are obvious ...

- The wiring is simplified (even if the power amplifier required)

- Now we have a center channel signal is available

- Provision for a mono signal to a sub-woofer is easy

The Schematic of an Enhanced Hafler Matrix Decode

While there have been published in the same circles over the years, this is a bit 'different areas. I wanted to avoid all the active electronics of the main left and right channels, as it eliminates any possibility of sound degradation due to the introduction of the threshold. Input impedance 50k does not cause any problems with the preamplifier (including types of valves), and the most important signal is simply a parallel circuit with the extras.

The volume is not included, because you already have a pre-amplifier. It would just become another component of the violin, and it would be little used, probably would have become a noisy time just sitting in a permanent position.

How it works

Opamp U1A is connected as an amplifier of the subtraction. If the same signal is used both as input, the output is zero. Consequently, it will remove all the background information from the stereo signal, and reproduce only the difference signal - exactly the same way as the original design Hafler.

U1B is a simple sum of the amplifier, and the food contains all the information as well as left and right channels. Ability to mind is that you could reduce the difference between the proceeds of this information, so the only material that is completely shared, both channels are reproduced. This would improve performance to the extent that an additional circuit is justified? I tend to doubt it, but you can pursue the matter.

Central control of the channel

Pot (VR1) is to set the center channel. This can be a TRIMPOT, or mounted on the back of a traditional dish (to help prevent the "fiddlers" from mucking your settings). I have seen circuits that do not have this, which basically feels like a bad idea. When two channels are added, the center channel is usually a level 3 dB compared to the left and right channels - if the signal is mono. Speech center channel (for example) is mono, so the standard is the same for each of the main speakers. Because the center channel amplifier and speakers are rarely as powerful as the left and right channels, it is very possible, the congestion amplifier, speakers, or both.

From the center channel is only supposed to fill "gaps" and provide a stable center of the image, which need not be so hard - especially because it is almost certainly lower than the main speakers sound quality and therefore reduce the overall sound quality. Level control lets you set the level just sufficient to provide a stable sound image, and no more. On my system, did not use a channel, and would have a negative impact on sound quality. If you have a good main speakers and a sound image stable and well defined, a center speaker can do more harm than good.

The capacitor (C1) is optional. Provides a nominal value of 8 kHz frequency roll-off (which apparently is quite normal for "real" surround sound processor). This helps minimize interference with the main stereo signal, but feel free to ignore, like most center channel speakers probably will not be able to play above that frequency anyway.

Subwoofer Out

The subwoofer output is simply taken directly from the mixing of the central canal, and I do low-pass filter, because I do not know any of the subgroups that do not have a filter in advance. Add another simply adds unnecessary complexity and will introduce the phase shift at the output of a phase compensation circuit (often included in the sub-woofer) may not be able to cope.

Miscellaneous

100 ohms at the exits to prevent the ability of the signal carried by the amplifier to oscillate. At that value, will not cause high frequency loss, unless you insist on 100 carries the signal of time (in my experience, these are rare).

It will also be noticed that there are two outputs for the rear speakers, just parallel. I included it because it is easier to thread if the user connects a stereo amplifier for rear speakers. Naturally, a mono amp do just fine as it is capable of performing the two rear speakers in parallel. It may not be possible if the speakers are 4 types of Ohm (it is becoming increasingly common in Hi-Fi, so it's not so stupid).