It's driving, cap coupled, a modified cathode follower (also a 6SN7, see diagram (b) above), with a split cathode resistor, 16K to Gnd and 716 Ohms attached to the cathode, the junction of the two biasing the grid. Paul Hide full thread outline! There is a paragraph about each if you look at my profile, here . I’ll try to confirm, but so that means you were suggesting going with the input side -- which if the tech is … The Mosfet is dead, and I am not going get rid them totally. The 6SN7 plate is then direct-coupled to the 6AS7/6080 grid. It employs a cathode follower to minimize impedance conflicts. Also, would a driver tube typically have more affect on the overall sound (i.e. Description Features Technical Specs. The price we pay for this is gain, which is slightly less than unity. Super … A toroidal power transformer for lower noise, 5U4G tube rectifier, one OD3 and one OC3 tube regulators, and an all film capacitor power supply offers very reliable power delivery with fast rise and decay times. Specification Tubes: two EL34 and two 6SN7 / 6SL7 Voltage gain: 22dB Operating frequency: 20-20KHz Input impedance: 250K Ohms These two circuits are powered by B1+ supply (about +400V, or so) which is decoupled from B+ (about +420V) via an RC filter. The 300B amp is a partial feedback (resistor from the 300B output plate to the driver plate) design. Bias may be adjusted by changing the value of either R17 or R20. However, by … By increasing the supply voltage for the second 6SN7 (one idea would be to use a choke in place of the 10K dropping resistor shown) and/or using multiple 6SN7's in parallel in place of the single 6SN7 cathode follower shown, even greater voltage swing … White cathode follower) or SEPP. The output power can reach 10W for each channel. gain stage is 6SN7 with 30K plate and 1K cathode, no cathode bypass cap and only 260 B+ (give or take). The majority of the THD generation is … From the 1960s onwards a variety of transistor versions appeared 12,13,1415, but still without the name SRPP applied. If high-gain was never our goal, but a medium-gain line-stage amplifier, then the following design is the better way to go, as it offers the same gain as the original SRPP-cathode-follower-based circuit, but delivers a greatly improved PSRR due to the Aikido cathode follower output stage. Which tubes would you roll out first if you wanted to change the sound of … The second is a hulk of an oil capacitor rated at 27 uF and 700 volt AC (990 volt DC). The input to the grid comes through a 100pF cap. The power supply is outboard. The best way to correct for this is to insert a buffer stage between the 4S and the LM1875. The preamplifier was built using premium parts, and a simple signal path was designed with sonic purity in mind. Cathode follower design (amp and modulator needed) I need a cathode follower circuit that can cover from 75KHz-16MHz using 1/2 of a 6SL7. The best way to correct for this is to insert a buffer stage between the 4S and the LM1875. This Cary Audio is a full featured, all triode, Class A tube preamp with a phono stage. I did come up with a question on the 6J6, dual triode that shares a cathode. These tubes sound excellent with tight low end and detailed highs. I think I can just omit the first stage of the guitar amp circuit and put the 6SN7 cathode follower/detector stage in it's place. This could be done with a vacuum tube cathode follower, a transistor emitter follower, or a solid state op amp properly configured for buffer operations. Bootstrapping, grid-leak and input capacitor: Now we have set the upper triodes conditions we can work out what AC load it present to the lower triode. A place for discussion, news, reviews and DIY projects related to portable audio … And, if you use a cathode follower after it with the same DC load resistor (22K in the cathode), and bias it to where it draws the same idle current as the gain stage, you effectively make just about a constant-current-draw buffered preamp. Think of a cathode follower like a grounded cathode amplifier in that the grid modulates conduction through the tube and load resistor. This is possible because the grid is biased negatively compared to the cathode (the negative bias is what allows it to modulate electron flow). Of course, we now use the term SEPP for the more specific circuit arrangement by Peterson and Sinclair. This could be done with a vacuum tube cathode follower, a transistor emitter follower, or a solid state op amp properly configured for buffer operations. Of course, we now use the term SEPP for the more specific circuit arrangement by Peterson and Sinclair. Zoom. I used the 6SN7 cathode follower to drive the grids of the 6L6s and the phase inverter/driver to drive the 6SN7. input impedance 50k ohms. Hi @ghasley I got my info from tech support at Schiit (quote):L/R on the Freya is actually input/cathode follower and top/bottom is l/r. The headphone amplifier circuits (figures 3a, 3b and 3c) use a single-ended triode class A gain stage and a paralleled-triode cathode follower output stage. Price. Canonical receiving tubes used in traditional amplifier design, like ECC83/12AX7, 6SN7 and so on, can result unsatisfactory therefore I prefer vacuum tubes with best electrical performances like WE437A, 3A167M, E55L, E810F and others. Power output: 20-80 watts per channel RMS (dependent on tube & mode) Variable negative feedback/damping. Using a 6SN7, a cathode load of 20k, and an input signal of 1V into a cathode follower yields the following graph: Note the absence of distortion harmonics beyond the third harmonic and the low distortion (less than 0.01% THD). The buffer needs a high input impedance and a (relatively) low output impedance. Salectric,Sep 26, 2017 « on: May 01, 2014, 12:52:33 pm ». First of all lets begin with the obvious – setting the tubes into the desired operation point. Compatible with EL34, KT88, KT120 and KT150 power tubes. This should drive any typical line, even one of extended length, without problems. How would this differ from the function of a typtical Driver tube (such as a 6SN7, 12AX7, 12AU7)? The first version with E82CC/5814 should be considered the starting point. direct coupled to a cathode follower buffer. Super … It has good sound but with some distortion because noval (new 9-pin tubes) tubes are not very linear. As a cathode follower, the 6SN7 will use a lower value cathode resistor than 68K. The cathodyne phase inverter is a cross between a gain stage and a cathode follower, because the total load resistance is divided into two parts and shared between the anode and cathode. These circuits are independently powered by grand scale, low ripple and low impedance power supply sections supporting high purity amplification stages. The problem with many 6SN7 tubes and layout is use of pin 1 as input. This product is purely a buffer - it will provide an easy load for the input device and a low output impedance to drive the output device. With-out negative feedback, this type of cir-cuit has very high gain (around 80) and distortion, and high output impedance. 3rd triode is 6SL7 grounded cathode amplifier to increase signal, also contains feedback input. The compliant constant-current source works to eliminate any DC offset voltage, a state only accomplished when its output current flow pulls the DC output voltage to zero volts. The output is capacitor coupled with 30uF per channel, giving a f-3dB point of 17Hz with 300ohm headphones and an output impedance of roughly 75ohms. 6SN7 is one of the greatest dual triode tubes ever designed. These circuits are independently powered by grand-scale, low ripple and low impedance power supply sections supporting high purity amplification stages. The tone controls are simple passive RC Baxandall filters (no negative-feedback loops). It combines desirable performance aspects such as high gain, low distortion, immunity from power supply ripple, and low output impedance. model B-4i ; Line 1, Line 2, Bluetooth with headphone output. A amplification with 6SN7 / 6SL7 as the input stage. Plus, as I said before, even with a proper circuit, I am skeptical whether a 6SN7 would sound better. 2nd triode is 6SL7 grounded cathode amplifier to increase signal, feeds volume. I experimented with a 6SL7 (differential amp/phase splitter) directly coupled to a 6SN7 (gain stage), followed by a 6BL7 cathode follower, driving push pull 300Bs. (I have many old GEs I wanted to use, and converting to 6SN7 means simply changing the hookup to the 24V filament transformer). Circuit design is configured with 12AU7～6SN7 x2 for amplification and 6SN7 x2 (cathode follower) for the driver stage to powerfully drive the large-scaled transmitter 211 tubes. Design of 6SN7 Differential Phase Splitter, with Feedback Port: I am trying to mod/fix Bada Ph12 amp. signal/noise ratio 85dB . Don’t have an aneurysm trying to understand it all immediately. 4th triode is 6SL7 cathodyne splitter (unity gain) Finals are 25L6 push pull, ultralinear The filter is followed by a 6SN7 regenerative detector / audio amp combo. 27: Re: Operating Point 6sn7 Cathode Follower as Preamp Out (10.95) Posted by danlaudionut on 2005-12-16, 18:40:02 (205.188.116.7) A white cathode follower is the "best" cathode follower going. = 30 * 10Kohm (next stage) / 8K + (30 * 10Kohms) = 0.97 . You also need to elevate the filament so heater to cathode voltage doesn't exceed about 90Vdc. How would this differ from the function of a typtical Driver tube (such as a 6SN7, 12AX7, 12AU7)? FYI - the inherent gain gain of the mu follower may just be too high, and the preamp may be picking uo hum. These circuits are independently powered by grand-scale, low ripple and low impedance power supply sections supporting high purity amplification stages. The common denominators are the 5AW4 tube rectifier, Goldpoint stepped attenuator, and similar point-to-point construction quality as seen below. Features. 2. A subsequent RCRC filter in each of the power supply channels drops the voltage to 500 volts B+ to meet the needs of the 6SN7 or 12SN7 (selectable) gain tubes and the 6AU5 cathode follower tubes. The second triode in the ECC82 could of course be used to amplify the returning effects signal. A cathode follower is simply an ordiary gain stage that has been turned on its head. Although the load is in the cathode circuit rather than the anode, a load line can still be drawn in the usual way (see the basic triode gain stage ). Which tubes would you roll out first if you wanted to change the sound of … The Aikido cathode follower PCB/kit is a modest affair, consisting of one tube per channel (two triodes per tube envelope) and a handful of capacitors and resistors. The 6L6s were connected in a conventional pentode configuration. Well, for the WA1QIX circuit, I use a triode connected 6L6 as the cathode follower and you can sub a 6sn7 or 6sl7 for a 12ax7 12au7 type tubes. The cathode follower can’t make the voltage changes at the cathode any bigger than the changes at the grid because it otherwise affects the difference between them and the difference is what determines electron flow. The cathode follower operates with 100% negative (voltage) feedback, which makes it exceptionally linear and minimises the output resistance. The audio amp is a cathode-follower which matches nicely to my roughly 300 ohm headphones. 4th triode is 6SL7 cathodyne splitter (unity gain) Finals are 25L6 push pull, ultralinear inputs four stereo . Why? The cathode follower's 6SN7 will idle at whatever current flow works for that individual 6SN7 with a 642-ohm cathode resistor terminating into 0V. 464k members in the headphones community. The B+ is 200V , 811A grid bias require +25V from the curve , the voltage between G1 and cathode of 6SN7 require 3.8V, so i have to bias up the 6SN7 In order to get +25V for 811A. Before the Mosfet is a cap coupling 6sn7 cathode follower. high B+, but because of «loses» of voltage in direct coupling, both tubes work with rel. This unity-gain buffer, using a modified cathode follower, offers a high input impedance, a low output impedance, low distortion, and a great PSRR figure. In addition, sound quality and reliability are offered because each tube is made with high specifications. 1 Matched Pair Shuguang Natural Sound Vacuum tube 6SN7-T 6N8P/6SN7/6H8C/CV181 1 offer from $169.99. Lots of overall negative feedback is used to get the gain down to close to 10 or 20, which reduces distortion and output im-pedance. It is an excellent choice for an enjoyable audio experience. There`re many other circuits that use 6SN7 for the 300B driver (SRPP, Mu-Follower…), and probably the most known is «cascaded» direct coupled triodes, Fig. The 6K7 I have, should work fine in place of the 6J7 for the purpose of this circuit, I think. Cathode resistors are un-bypassed, for now. The 6J5 uses an octal base. A 6SN7 in grounded-cathode mode with an 8mA constant-current source plate load will show less than 0.04% THD at 20V peak; selected samples will show even less. Some just prefer the sound from octal tubes, such as the famous 6SN7, so … Unfortunately the latters are rarer and expensive. However, by … ... 1255-6sn7-mu-follower-cathode-follower-mu-png increasing the R4 to 5.5K and found that there is no hum now. Yep, those plate curves look about what TubeCad told me, when I was laying it out at first. After inspecting the 6SN7's plate curves, we see that a cathode voltage of 6.5V is needed to establish an idle current flow 5mA with 200V plate voltage (actually with the plate voltage equaling 200V – 6.5V, which gives us the cathode-to-plate voltage). It won't drive 600 ohms without a transformer, though. The above is just an honest attempt at learning something new in a field I still know very little about. Cathode Follower Gain: Formula = mu (RK) / (rP + mu (RK) The load of the subsequent stage will be paralleled on to RK for full accuracy. Buy New 1 Matched Pair PSVANE 6SN7-SE HiFi AMP Vacuume Tube Re 6SN7 CV181 6N8PA: Tubes. I used a bunch of 7pin tubes, made a triplet SE 6AU6 amp, driven with a 6sn7 (octal) and a 6j6 as cathode follower into the triplet, was a grungy sound susceptible to RFI. Below is the 6SN7 cathode follower design . 28: Re: Operating Point 6sn7 Cathode Follower as Preamp Out (10.96) Posted by danlaudionut on 2005-12-16, 18:40:02 (205.188.116.7) A white cathode follower is the "best" cathode follower going. The cathode follower, once again, does its job. I may have to contact the manufacturer to find out. It has been used in many popular guitar amps including the Fender (push-pull) Princeton, most Orange amps and several Ampegs. Circuit design configured with 12AT7 / 6SN7 for amplification and 6SN7 (cathode follower) for the driver stage to powerfully drive the large-scaled transmitter 211 valves. Lets consider a fairly typical power supply voltage of around 300V and a 30kohm plate resistor which results in a plate current of 10mA. signal triodes 1 X 6SN7 (GT, GTA, GTB, WGT) cathode follower 2 X 6AH4 Single Triode. A cathode follower circuit is unity gain, actually a hair less than unity, so there won't be any change in overall gain if you change CF tubes. Well, it's hard to glean much about the design without seeing a schematic, but it sounds like they are running the two 6N8P / 6SN7 as parallel cathode followers. From the 1960s onwards a variety of transistor versions appeared 12,13,1415, but still without the name SRPP applied. This configuration retains the load resistor as a load for the cathode follower stage. The ideal setup would be some dual disimilar triode octal tube to mimic the 6EW7 type tube plus a 6sn7 as the microphone cathode amplifier, coupled to another triode acting as a cathode follower. https://lilienthalengineering.com/100-amplifiers-chapter-1/ Peace, Paul D dramadisease Well-known member Joined Jun 17, 2004 Messages 110 Location portland - or May 23, 2005 #3 The pinout is pictured on the left. Three months after testing the amplifier with the Hammond output transformer I tried it with the product of a new player on the tube transformer stage, Edcor. Power output: 20-80 watts per channel RMS (dependent on tube & mode) Variable negative feedback/damping. In addition, the ACF-2 produces a tad bit less distortion than comparable cathode follower by using the triode’s own nonlinearity against itself. It has an amplification factor of 20 which classifies it as medium mu triode. $7750.00. The 6SN7 circuit is a grounded-cathode stage, DC coupled to a low impedance cathode follower, which is then coupled to the outputs using premium Audyn True Copper capacitors. Greeting. Features. PC-5T: Grounded Cathode Amplifier/Follower for 12V tubes. For example when the grounded-cathode amplifier sees a positive going input signal, its plate current increases, which increases the voltage developed across the plate resistor, which in turn swings the plate voltage down. 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The plate resistance is about 7kOhm which makes this tube usable with transformer coupling as high gain ( around ). Equipment: Date first Available October 29, 2019 without the name SRPP applied very high gain ( around )! Or RC coupled or as a cathode follower is biased with a circuit... Did come up with a 1K 25W wirewound resistor each if you look at profile! Very linear watts per channel RMS ( dependent on tube & mode 6sn7 cathode follower Variable negative.! Purity amplification stages cathode amplifier to increase signal, feeds volume octal..