6n6p Kit Manual

Lampizator Kit 6NxPApplication Manual

By Lukasz Fikus

This kit represents a very well known and tested application of tube triodes in audio amplification stage.It is so universal and versatile that the number of possible applications is very large. It can work with tens of different tubes and tens of different sources.

This design is very immune to power supply quality problems, very stable, and very tolerant of parameters, loads and errors.

We believe that properly implemented KIT can be a part of any high end system, however ambitious and / or expensive.

LampizatOr KIT 6NxP manual

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TUBES:• This kit has been designed with the 6N6P tube in mind, but it will work for all

tubes which have:• 6,3 V heaters on pin 4 and 5• Anodes on pins 1 and 6• Grids on pinsd 2 and 7• Cathodes on pins 3 and 8• Pin 9 is grounded and in soviet tubes it represents the screen between two

triodes.These tubes are: noval, triodes, dual type (two identical triodes in one bottle.)They are indirectly heated and share one common heater circuit.

Possible tube types are: 6N6P, 6N30P (not recommended), 6N6P-I (Impulse variant, not recommended), 6N1P (all variants), 6N2P, ecc88, e88cc, 6dj9, 6922


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APPLICATIONS:This kit can be used as:CD player lampizator with U-Out DAC type and I type DACDVD lampizatorDAC Lampizator or simply output stagePreamplifier stageAmplifier input stageOther, like tuner stage, sound-card lampizator, I-Phone amplifier etc.

TOOLSTo complete this kit we need:Soldering iron of 40-60 W, preferably a DC stationSolder with lead (no silver and no ROHS solders please)Wire strippersUtility knifeUniversal meter

An oscilloscope is very good but not strictly necessary.

If you buy your first oscilloscope, get a 50 MHz type or faster and CRT display, NEVCER LCD.

CIRCUIT PARAMETERSThere are three main circuit detrmining parameters:1. Heater current2. Anode idle current (bias current)3. Input signal volume and amplification

HEATINGWhen we roll tubes all three of the above will change but the circuit will still play. It will not get damaged or damage tubes.

Ad1. Heater current is a function of tube heater resistance connected to the 6,3 V supply. 6N6P, its sister 6N6P-I and brother 6N30P draw circa 0,8 A per tube. That is the largest load of all noval tubes known to me. Consequently: AC heaters will have a voltage sagging of transformer secondary, AD unregulated supplies will need very small recistor in CRC and of a large wattage (5 W). The regulated circuits will require a 6,3 V DC regulator with large heatsink and only one tube per regulator can be used. For stereo pair use two regulators fed from one common 6A bridge and with at least 6800 uF /16 V cap after the bridge. 20 000 uF would be better.


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For AC heaters we need dedicated circuits from transformer secondary with precisely 6,3 V AC under the load. Since the load is only circa 10 Ohm (on hot tube 10 Ohm, on cold - 1,5 Ohm !) Our secondary winding must be rated at at least 2 A per tube supplied. Without load such transformer secondary will measure circa 7 V AC.

The board has heaters SEPARATELY for both tubes. You should connect them in parallel for using a common 6,3 V heater source.

For the music - it does not matter if the heaters are AC or DC. DC will not hum but require more parts, more work, more skills and they have more potential areas that can get damaged. I encourage you to start from AC heaters and finish the project. Later you can convert to DC heating.

For one common heater supply (AC or DC) connect parallel heaters: 6,3 (left hole) of one tube to 6,3 terminal left hole of second tube, and the same for right holes.If our transformer has a slightly too high AC windings, we can add resistors which will reduce heater voltage. R6 and R7 are on PCB (marked 1 Ohm) just to drop heater voltage.If say out voltage AC on pins 5 and 4 of tube are 7,3 V that means we have one volt too much. OVERHEATING DESTROYS TUBES! If the tube is 6N6P so it will draw 0,8 A, from ohms law to drop 1V we need that the current of 0,8 will generate a drop of 1V on resistance of Rx , so Rx = U/ I = 1 / 0,8 = 1,25 Ohm. We decide to split this value in half and add TWO resistors of 0,6 Ohm in place of R7 and R6 (and in other tube of course R6_1 and R7_1).

The yellow capacitor (use only one, even if the PCB has place for two) is for creating a virtual point of earth reference for the heater circuit. It connects the pin 4 or 5 to ground.

If we want to build a DC regulated heater, we use:- 4 A (or bigger) bridge, followed by 10 000 uF/10 V cap (or 16 V), followed by the 5 V

regulator, with a cap after regulator min. 100 uF/6,3 V (can be as big as 10 000 uF - this does not matter).

The regulator must have aluminum heatsink surface not smaller than the green project PCB for example. The larger the better.The head of the regulator must be insulated from heatsink by mica or teflon washer and the screw must be insulated by a collar type washer as well. The center leg of 7805 regulator must have two series diodes to ground, with both plus marks towards ground. These two diodes change the output from 5V to 6,25 V ideal for heaters.

Ground (minus) of the regulated system must be connected to PCB ground.


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BIAS CURRENT:Bias current of the SRPP system is determined by Rk of upper and lower triode (both must be the same R values and types !)Our system can handle Rk from 140 - 1000 Ohm range (1/8 W or more) We recommend values between 240 and 380 Ohms.This value will fit all tubes listed.

ATTENTION: the PCB has silkscreen mark of 1K, please ignore it.

The cathode resistors are marked R1 and R4.

The bias, depending on tube type, will be from the range of 10 mA to 1 mA. 6N6P will draw 10 mA and ecc88 will draw circa 3 mA of anode current. (at circa 275 Ohms in cathodes).


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GRID INPUTThe signal from the source must get to the grid to make the tube “play”. The grid pins (2 and 7) are connected to “something”.Pin 2 is connected to the reference point below its Cathode resistor which makes it a CURRENT SOURCE (upper triode)The pin 7 is grounded by a Grid resistor Rg.(note that it is also connected to a reference point below its cathode resistor like the upper one).This grid resistor R5 must be small enough to set the grid on ground level (from 1 Mega Ohm down to 0 Ohm are acceptable for that criteria) , but large enough in order not to influence incoming signal (2K to infinity is accepted). The compromise resistance is usually set at 250k-600 K Ohms. R5 on PCB silkscreen is marked 1K, please ignore it.

A keen experimentator may try to ground the grid with a wire and send input signal directly to cathode Pin8 , it is very interesting.

SIGNAL INPUTWe have infinite number of scenarios, depending on tube application, volume of source signal, impedance of source, cables used, etc.

Scenario 1 - we need full amplification of Voltage (maximum that the tube circuit can offer.We send the source signal to Input+1 point. We short R3, Nothing is in R2.The amplification is full. 6N6 offers lowest amplification in SRPP - circa 10-20 times depending on many factors.ECC88, E88cc, 6dj9, 6922, 6N1P tubes offer medium amplification between 30 and 50 times.6N2P offers circa 100X amplification.

Scenario 2: If we need less amplification, say in a DAC the chip has a 2 V pp signal strength and we desire circa the same on output, we must use L-Pad divider.R3 and R5 form the L-pad.

The design criteria of L pad are: R3 plus R5 must be larger than 20 K and smaller than 100KR3 must be 4 to 10 times larger than R5.R5 is no longer around 250k-300K like before.The factor of 4 means small attenuation, factor of 10 means over 11 times attenuation (much).

Example: we use 6N6P and a DAC with 2 v PP output and we want a 3 V PP output at the end of the Lampizator.We choose R5 = 10 K and R3 = 47 KSum = 57 K which is OK.


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Ratio of reduction is: (R3+r5)/R5 = (47k+10k)/10k = 5,7 times, a perfect match for 6N6P.

Scenario 3 - like Scenario 2 but our DAC likes a strong bias of output stage:Reduce the both R by the factor of 10R5 = 1 k and R3 = 4k7Ratio is the same but small resistance of R3 plus R5 (5k7) gives stronger bias of DAC.

Scenario 4- I out DAC (current DAC like TDA1541 or AD1865 or PCM63, 1702, 1704 or 1794 or 1798 (new Lampucera).

In this scenario: there is no input capacitor between DAC output and tube input grid (pin7). The Rg (R5) between tube grid and ground becomes the voltage converter for the DAC.The Rin (R3) is shorted.The Rg (R5) has a value recommended for the given chip. 82 Ohms for TDA 1541A, 280 Ohms for TDA1543, and so on.The tube should be of high amplification, the best being 6N2P or E88cc / Ecc88.


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PREAMPLIFIER SCENARIOthe pre configuration should have input impedance of maximum value, so R5 plus R3 should give around 100K (if we donʼt use a pot) . Low amplification tube is the best so letʼs choose 6N6P. Since we need no L-pad attenuator, the pot takes care of attenuation. So we install a pot (100k Log type) at the input after RCA and then from center tap of the pot (wiper) we go directly to tube grid. To tame oscillations we install 1K resistor (between 1K and 10 k whatever you have) directly at R3 (R_input) and R5 becomes as high as we can find. 500K (max. 1 Meg) is OK. (no less than 200K).


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The wires between the source (DAC chip or preamp input and pot) may be shielded (screened) or not. Only in case of I out DAC the cable MUST be screened. The screen connects on only one end to the system ground.

The best POT regardless of the price is the V-02 TAIV kit available from our shop. Expensive it may be but it represents the cleanest and most pure attenuation known to man. It gives the added benefit of remote control, 64 steps, 4 analog inputs switching, display, and 3 output relays for extra features.

Anode Power SupplyThe SRPP is magical because it will work well between 50 V and 270 V power. The ecc88, e88cc, 6dj9 and 6922 tubes tolerate no more than 200 V on anode. Since there are TWO TRIODES one on top of another, one tube sees only half of the voltage. So if you check datasheet for tubes and your Anode supply is say 220 V, check the curves for 110 V of voltage on anode.The SRPP is magical again because it handles well even weak, poorly filtered and inadequate supplies because the SRPP config cancels out these factors.

The Anode supplies can have two quality levels: CRC and CLC. Each level can be just monophonic CRL or CLC or it can split the voltage in two channels like C->twoRʼs and two Cʼs. (or put L in place of R).

On top of that, the supply of CLC can be fed the DC from a solid state bridge or tube diode.There is a Tube Power Supply kit available for that.

Summarizing: Anode supply can be approached like that:(in order of better quality)

1. CRC (120 uF/400V -> R 6k6, -> 120uF/400)2. C2R2C (120 uF/400V -> 2 x R 6k6, -> 2 x120uF/400)3. CLC (120uF/20H/120uF)4. C2L2C (120 uF/400V -> 2 x L 40H -> 2 x120uF/400)5. Tubed diode CLC (6uF, 20H, 240 uF)6. Tubed diode C2L2C (6uF, 2x 40H, 2 x 120 uF)

The perfect tubed diode is soviet 6u5C or American 6x5

The optimal end result voltage on the kitʼs anode (tube pin1 ) is between 180 and 240 V DC.


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TO make sure the kit works well, measure the voltage on pin 2 or 3 or the first leg of output capacitor MBM 1uF - it should be 1/2 of U Anode plus 3 V. For 200 V anode B+ the output voltage will be therefore 103 V plus minus 5.

To measure the current of bias (idle) we measure the voltage DC on pin8 (cathode of lower triode) and divide it by the value of Rk (R1). So if the Rk is 300 Ohms and voltage there on pin 8 is 3 V the current Ia is 3/300 = 0,01 A = 10 mA.

OUTPUTThe output of SRPP can be pin 2 or 3 depending on our mood. It makes no difference. The output contains am AC component of music and also DC component of half of anode supply. The output cap filters out the DC and passes music.We chose a very good aluminum paper in oil cap MBM of value 1 uF. The minimum value of this cap is 220 nF (0,22 uF) and there is no maximum but optimum is around 0,4-2 uF. Our choice 1 uF is right in the middle. Only caps costing 50 Euro a piece and more can match our MBM cap .To better it go for Copper Foil caps like Jensen, Audio Note, V-Cap and maybe Mundorf or Clarity cap.To prevent the amp from lout THUMP when we plug the RCA cables , we recommend to use output discharge of static resistors. We must solder the resistors at RCA outputs between hot and ground. 300K plus minus 100K is the best value. It will keep the DC on the output at zero level. 1/8 Watt is enough.

The wires to output need not be screened.

The output caps must have voltage rating of MINIMUM 160 V DC and no more than 1000 V.

GROUNDthe whole green area of both sides of our PCB is a ground. You can access it by scratching off the solder mask lacquer. Remember to connect all system grounds together: DAC ground, Green PCB ground, RCA grounds, heater DC supply ground, Anode supply ground, chassis, AC three pin IEC socket, and screens of cables if any (between DAC and the tube grid.

If the AC heaters are used, then hum will appear before we add yellow caps. If we use NO RESISTORS IN SERIES to heaters we need just one yellow cap (well, maybe it is not yellow anymore but we still use this description for any 0,5-1 uF cap on heater pin 5 or 4). If you use resistors in series as described elsewhere above to reduce voltage, then both yellow caps are necessary. If you use two independent AC windings even without resistors - then both yellow caps are needed to kill hum.


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ASSEMBLY of naked PCB:First do all resistors, because the tube sockets will disturb you. Do the noval sockets last. Our recommendation is this: first install all resistors, solder them on the other side, cut the wires short with snips, (clippers) and then resolder the other side of PCB a little. Last, touch the first side of joints with the iron to make perfect point after clipping. Re-shape the solder to a cone again this way.

MOUNTING THE PCBThe PCB can stand on the PCB legs, as we provide 8 holes for that. If the legs are made of metal, to prevent shorts we recommend to use collar type plastic washers. Or simply use nylon legs so popular these days. M3 nut secures the mounting. We need at least 3 or better 4 legs, not 8. Choose the holes with best spacing of legs and nuts from traces and colder points. REGRETTABLY SOME HOLES ARE TOO CLOSE TO PUT A SCREW OR BOLT WITHOUT TOUCHING ADJACENT ELECTRICAL CIRCUIT.

FUSEThis kit will benefit from having a fuse on the mains transformer. Only one phase is enough to be protected. 0,5 A slow blow is good, or 1 A fast one.

Working with the basic transformer of the kitThe basic kit has the LTR2 transformer - a toroid with a 25 VA core and three windings:1. primary mains winding of 0-115-230 V AC. Use external two windings for 230 V

countries (UK as well) and ignore (insulate) the center wire for 115 V. For USA and Japan - use one external wire and center wire, insulate the other external wire. Primaries are with double thick insulation.

2. Secondaries are 6,3 V 2 A and 180 V 0,1 A. Use the 6,3 V secondary directly as heater AC or rectify it to make DC heater .

3. 180 V AC secondary is the first one after the primaries (middle winding). Rectify it and filter it according to the manual. Use a bridge of silicon integrated “square or round pill” or use it for tube rectifier.

For systems using additional tube rectifier kit, use the LTR2 to power the heaters of the kit and the second transformer of the power supply will provide the high voltage DC.


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TESTINGTo fire up a project I suggest the following:1. Do not connect 250 V yet. Just connect the ground and heaters 6,3 V . Fire up the

power. The tubes will start to glow in about 10 seconds. Measure the voltage across pins 4 and 5 of the tube. The voltage should be between 6,0 and 6,4 V. The circuit is tolerant.

2. If the voltage exceeds 6,4 V then add or increase resistors in heater circuit series. (R6 and R7). Keep them (resistors) both the same for AC heaters or just use one for DC heaters and short the other one.

3. If heating is stable and voltage is OK, disconnect the power and add B+ 250 V (or whatever it is). Fire up again.

4. After the circuit stabilizes, the measurements should be:

- pin 1 = 250V or whatever it is (letʼs call it B+)- pin 2 = 1/2 of B+ give or take 5 V - in this example 130 V- pin 3 = pin 2 (less 2-3 V maybe)- pin 4 = heater one- pin 5 heater two - measure voltage between 4 and 5 (DC or AC)- pin 6 = pin 2- pin 7 = 0- pin 8 = between 1 and 4 V, whatever it is. - Pin 9 = 0

R6 and R7 need to be higher wattage, 1 W is best. Otherwise they may get warm and even smoke.

TUBE SWAPPING (rolling)We can swap tubes freely between all listed types except that if we use AC heaters with resistors R6 and R7 - the heating current will be changing very much.High current tubes are 6N6P, 6N1P, 6N30P - they all draw circa 07-08 A. The other tubes are low current (circa 0,3 A) so if the resistors are optimized for high current, when we plug the low current tubes the voltage will increase and tubes will overheat. It is possible yo use them for no more than 5 minutes for sound test but donʼt use them permanently.If resistors were optimized for small current tubes, changing them for high current will cause voltage drop on resistors and voltage decrease. The tubes will be undrheated.They can be used and tested for sound for a couple of minutes even with as little as 5 V on heaters.


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TUBE PIN ORIENTATIONThe tube pins are counting from 1 to 9 when we look from the silk-screen side, clock-wise from the gap in pins. Last pin is grounded. Looking from the other side of PCB the pin 9 is SQUARE.

BALANCED OPERATIONFor balanced circuits use two same kits. One kit will serve one channel. One kit will have two phases where previously it had two channels. Therefore balanced operation is in fact four times mono amplification.It is unimportant which phase is which channel etc. Just donʼt mix up phases on output so the sound is not out of phase.If your DAC chip has 4 outputs - it is balanced - it will have L+, L-, R+, R- and all foiur must be lampized by one tube each. Then output goes to XLR male sockets.


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6n6p Kit Manual

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