12at7 Cathode Follower









The circuity use five tubes as ECC 88/6922 for moving coil and two ECC-81/12AT7 for moving magnet (as passive riaa equalization) and one ECC-81/12AT7 for output as cathode follower adaptor, all tubes are accurate selected at very low noise operation. Plugged a guitar in and she roared to life!. GENERAL ELECTRICAL Series Parallel Cathodeâ Coated Unipotential. If one wants to build the highest quality amplifier with no compromises this. The only alternative suggested, and this with a caveat that the inevitable degradation will be subtle, is to use a 12AT7/ECC81 for the 5965 cathode followers. 95 in kit form or factory-wired for $229. Really the same valve, BUT, it has a heater to cathode limit of 200 volts!. I typically use Tung Sols in the first preamp stage because they have a warm sound. When you look at them you can't help but think that they must be rugged and good for the musician on the road. Could be an interesting battery project Aren van Waarde's 6AS7G Cathode Follower. At $444, in the 60's, the original 275 was not cheap. Circuit of the receiver. The ECC99 is a power triode that delivers big currents at low impedance, ideal for KT88, KT90 and 6550 tubes. Auto-bias amplifier, do not need and action when replace the tube. Yet, many counter examples exist, great sounding tube-filled pieces of equipment that hold cathode followers. 048″ wide on the larger. The Sovtek Long Plate Spiral is a great tube in either V1 or the Phase inverter socket. 35 KC Osc and Cathode Follower: 6EA8. Other capacitors are ceramic. This provides DC bias for the cathode follower. switch cathode follower v 5-6 1/2 12at7 sweep position r 45 voltage 15k c 17 r 46 2. output from the cathode-follower second section is 1. The silver version of the Chime is an upgraded version of the original, with. I would also keep one of the tubes in V1 or V2 as a 12AX7 and see if the 12AT7 in V1 or V2 makes much of a difference. Four pairs of loading plugs are supplied to optimize the resistance for your mc cartridge. Anyone tried using them in a circuit where one side is a gain stage, and the other a cathode-follower buffer (e. It measures 0. Where there can be issues is if you try to run them with high heater-to-cathode voltages (like in a cathode follower), because the h-k insulation isn't what it use to be in modern production tubes. The cathode follower takes great advantage of the triode’s inherent degenerative local feedback (therefore, unity gain). Cool White Follower output stage provides low 50 Ohm output impedance. Specifications. The Motherlode is a military-spec ultra high end preamplifier utilizing a separate dual power supply for the lowest. But, if it sounds great that is all that really matters. The Cure eschews the Z-Lux’s onboard reverb and tremolo and halves the power to bring you 20 watts from a pair of cathode-biased 6V6s fronted by a single-channel preamp that merges tweed Fender and basic Marshall topologies, while also enabling some blackface-like shimmer and bark. It may be compared to a 12AT7 or a 6SN7 and it will work also with a supply voltage of +100VDC up. Put both pairs of your old tubes in and listen for a while to get a good handle on the sound. The second triode is acting like a cathode follower for the local oscillator signal. Other readers will always be interested in your opinion of the books you've read. The 6922 is a special quality double triode. Additionally, the A-100 also has custom output transformers, and all stages, apart from the KT88 stages, are powered by fully stabilized power supplies. I had concerns would this make the pow. V2 and V3, also RCA-12AT7's, are cathode coupled multivibrators operating at 100 Kc and 10 Kc, respectively. 10 update stage, the auther found a another sample that seems to be easier way to explain the STC circuit. The Shrimp can drive anything, not to worry. Note too the 12AT7 has a. It may be compared to a 12AT7 or a 6SN7 and it will work also with a supply voltage of +100VDC up. I also used a direct-coupled cathode follower 12AT7 after the 12AX7 phase inverter to really drive the power tubes - similar to the old SVT bass amps. Amp designs that use a cathode follower stage by design should enable the Hot Mod V2 to work. I never like the tube 7247 (strictly vis-a-vis 12AX7/U7/T7!) for it is never vintage enough and never has the wide versions of tube that 12AT7 offers. 98, which greatly reduces the output impedance and increases the output force, by adding a deep NFB, the closed loop gain is about 11 and the NFB is 47. For more clean headroom in your amp, order this tube with the low gain option at no extra cost. This is accomplished without a cathode follower or solid-state buffer in the. Regular SLO100 tonestack. A cathode follower (or a high voltage MOSFET source follower) should be used to ensure the output impedance is low enough to drive the external amplifier and the interconnect lead capacitance. V12 V13 V 14 V18 V19 V20 V21/ V22 DI 1)2/5 6BA6 6AM6 6AL5 6489 12AT7 12AT7 6BE6 12AU7 6AM5 6AM5 OB2 IOOSC2 DD006. 1 MOUNT lNG. The buffer needs a high input impedance and a (relatively) low output impedance. follower is the value of the cathode resistor, divided by (the cathode resistor's value times the tube's transconductance, plus 1). A 220K will do on the grid. 12AU7 * * * * The 12AU7 sounds like a 12AX7 but produces a lot less gain in the preamp circuit. Sep 10, 2004 #6. 12AX7? Found a stash of 12BH7a tubes in Grandpa's shed. Instead the 355 provided a cathode follower, line-level, preamp out -- Just add the basic power amp of your choice, usually a Scott Type 208, but Mac's and Dyna's were also popular choices. Unfortunately this channel sounds really muffled for guitar. Each channel consists of a 6AK5 cathode-follower driving a 12AU6 differential pair which drives a 6AU6 differential pair. SOLD Sylvania Gold Brand Gold Pin 6201 (12AT7) This is the tube for the Earmax Pro. 9 Profiles. Here are the measured data for a 12AT7/6201 in totem pole operation: B+ = 310 V (this is non-critical) Bottom tube cathode resistor = 1 K ohm Bottom tube cathode bypass capacitor = 1000 uF/6. When they are set up as cathode followers, the cathodes can see 150 to 200 volts depending on the design. For the I-out DAC types allways use 6N2P!. Svetlana 12AX7 - For several years the original Svetlana 12AX7 tube from St. Each channel is made up of 3 triode tubes ( 1/2 12AT7 , ECC81 , 6201 ). The valve operates as an AGC mu-amplifier with a floating source, cathode load and gain of about 50. Double-sided gold-plated PCB LSDY tube voltage stabilizing circuit power PCB ARC tube voltage line 6Z4 rectifier tube 12AT7 as a voltage comparator 12B4A as voltage adjustment, adjustable voltage from 150V ~ 400V, with a group of filament voltage, output voltage of 6. Kingsnake: 495v. The buffer needs a high input impedance and a (relatively) low output impedance. Both of the two tubes in the line stage are in a feedback loop so it would be important to use a tube in the V4 position with the same Rp and Mu as a standard 12AT7. Air Tight's Single-Ended Triode Power Amplifiers ATM-300 30th Anniversary Version. The current production Svetlana is a New Sensor product and is a member of 12AX7-EH and Tung-Sol 12AX7 family. The ECC99 is a power triode that delivers big currents at low impedance, ideal for KT88, KT90 and 6550 tubes. 00 USD; Treble-Boost Normal Gain $50. Electro-Harmonix 12AX7 Data Sheet. Zůstaňte v bezpečí a chraňte své zdraví. GM3WOJ: ZL1CT: Vintage : transceivers: valve/tube: information: Collins: KWM-2A: Hallicrafters: SR-150: Drake: TR-4C: National: NCX-3: Swan: 350: Swan: 350-C: Yaesu. Young Ahn 450 views. That meant an impedance around 75K. Applying cathode NFB requires bigger driving amplitude for 300B. In your amp, the 12AU7 is used as a cathode follower to buffer the CD input and also used as a cathode follower for the output of the l 36: RE: To worry about which variety of 12AU7 is better, seems a bit pointless to me (6. I have Sylvania JHS 12at7 as a driver and Amperex 7062 as Cathode Follower and love the results - your results might vary. Definition of "xy-stereo": XY Stereo microphones contain two directional capsules mounted in a “coincident pair” arrangement: physically close, but pointing 90°-135° to one another. The Sovtek 12AX7LP/LPS series has a large plate format that gives a large soundstage with a lot of detail. Vacuum tubes fall into three mainly non-interchangeable categories regarding their heater or filament voltage/current, though some tubes' heaters run at both a standardized voltage and current, e. I'm thinking that maybe I'll convert this channel to the 5F6 bassman preamp circuit. Specifically, in a 12AX7 tube used as a “cathode follower”, the voltage difference between that present at the cathode, as compared with the heater voltage, can be withstood or tolerated by certain types of tubes, whereas other tubes will fail. There are differences in how the phase inverter gets the signal. The output is a constant-current cathode follower. Neumann wv2 eq + marantz7 cathode Follower = Low impedance EF804S+ECC83 TSD15. Note that the following stage must be protected against high voltages if a MOSFET is used, because the output will jump to the full supply voltage when. 218 is designed to provide demodulation facilities for independent sideband and single sideband suppressed carrier signals, when used in conjunction with the RACAL RA. NOS JAN ECC83/12AX7s are recommended for this position. While the driver tube should be an ECC81 family member (12AT7, ECC801, 6201, CV4024, etc. Introduction. Therefore the use of a shunt NFB network using R3 and R8 is needed to reduce overall gain at maximum volume setting = 1. Electro-Harmonix 12AX7 Data Sheet. I often use the JJ ECC803 Long-Plate (because I got quite a few of them) in place of a standard ECC83/12AX7, except in the V3 cathose follower position. Tried V3 (cathode follower position), it was super weird electrical noise, even at zero volume master! I quickly removed. The EQ is also footswitchable. In that application, a 12AX7 will operate as a more efficient cathode follower, because it is the inherent gain of that tube coupled with the inherent 100% NFB of the configuration that is largely. We always recommend JJ valves for the Marshall DSL40C amplifier. Another objection to the 'X7 triode as a CF is low plate current. cathode follower van 1'2 f2at7 9 r 21 100 2 2qov r22 meg sweep freq. tweed-Fender-derived cathode-follower tone control is used very differently). Bandwidth Let's examine how the 6DJ8 has 40x better bandwidth than the 12AX7. The SVT's preamp uses the 12DW7 (half 12AX7, half 12AU7) with the "12AX7" side as a gain stage and the "12AU7" side as a cathode follower. - Jsawyer09 08:27:58 09/09/19 (0) At the time it was made, were 12AX7s massively cheaper, or was the company too cheap to as a cathode follower?. The V80 uses a single 12at7 for an input and a pair of 12au7's for driver/splitter tubes. Well some people say that any cathode follower using a 12AX7 is a poorly designed cathode follower! The main advantage of a CF is high input impedance and low output impedance. Triad transformer isolated balanced output (600Ω impedance) with +6dBu gain allowing direct connection to mixing. It also has a cathode follower driver tube, which is an additional 12AT7 located in the power section. While the KWS-1 Transmitter is capable of AM, SSB, FSK, or CW operation, its design emphasis on SSB perhaps warrants description in the SSB condition. I remember referencing the TILT circuit when I was David Manley's design and prototyping assistant, but I can't quite remember where he got the TILT circuit from. The 355 added true FM-MPX stereo reception utilizing the 350/335 decoder design, incorporating the "Stereo Guide," 6AV6 tube indicator. 3 V at 300 mA or 13 V at 200 mA, making them suitable for either series or parallel operation. Specifically, in a 12AX7 tube used as a “cathode follower”, the voltage difference between that present at the cathode, as compared with the heater voltage, can be withstood or tolerated by certain types of tubes, whereas other tubes will fail. If you have any 6BN6 circuits or experience, you can apply that knowledge when using the 6Z10—and the power pentode section is (like the 6T9's) a 6AQ5A. Conclusion: good gain, but its too entitled to my opinion. This means that, in a monaural setting, there will be one 12AT7 triode left over. The Vackar series-tuned v. Low plate resistance tubes give low output Z , and while not many can get much below 1K ohm they can do a good job , with a little or no feedback. ) I think these boards are very nicely thought-out and implemented. 0012RLOAD V(0-Peak) = 0. cathode follower van 1'2 f2at7 9 r 21 100 2 2qov r22 meg sweep freq. Audyn True Copper coupling capacitors. Channel switching in ALTERNATE mode is done using diodes. Good walk-through of technical design principles. Starting in the late 1960s, together with Marshall and Vox, Hiwatt contributed to the sonic image popularly termed "British sound". Instead the 355 provided a cathode follower, line-level, preamp out -- Just add the basic power amp of your choice, usually a Scott Type 208, but Mac's and Dyna's were also popular choices. Since the voltage at the cathode "follows" the grid, there is very little current through C GK, so this capacitance all but disappears. I don't know if I would put this in a cathode follower slot, but in V1 its very close to my 50s RCA long black plate 12ax7s, and in the phase inverter its about the best new production tube you can get. It's easiest for us to make a VCO by varying the sensitive grids of our 2D21, so we will drive it with a cathode follower made from half of a 12AT7. Because the capsules are close together, the mic should produce no phasing problems in the stereo signal, which in turn means that the stereo signal created. MM Phono Stage Gain 46dB. The breaker automatically resets after a few minutes. I use 1/2 of the tube for each channel, bias it at the same 10mA. There are differences in how the phase inverter gets the signal. The preamp is where the most important differences lie: It uses a cathode-follower approach to drive not only the tone stack, but also the built-in compression circuit—which has its own effects loop for inserting additional pedals (like an overdrive) that can alter the attack envelope and fine-tune how aggressively it clamps down on your signal. The gain is foregone for 0 , 6 , 10 , 14 and 20dB. Perhaps i'll try 5K1 grid resistor instead of 1K5 on power tube in first time. This entry was posted in 12at7/ECC81 by. 12AT7 & 12AU7 normally operate at much higher current vs 12AX7s & 5751s. Insanely tweakable, and promising the ability to mimic your own amp, could this be the last word in amp modelling? For any guitarist, there’s a reassuring air of familiarity and class about the Bias Head’s black, grey and silver enclosure, but its front and rear grilles are purely cosmetic — inside lurks a 25-preset, deeply programmable combination of Positive Grid’s highly regarded. The output tube in this configuration provides both voltage and current amplification. Filament supply floated 80V above chassis ground for quieter operation and longer. It splits the signal by virtue of the fact that the signal appearing at the cathode of the tube is in-phase (this circuit by itself is called a “Cathode Follower”), while the signal at the plate is out-of-phase (this is a typical Common-Cathode amplifier). If Fender, then you could use this as a cascode stage (12AT7) to drive a reverb transformer if you wish to build the reverb circuit into your amp. (1mA cannot drive 600pF!) Preamps with 12AU7 cathode-followers aren't much better, sounding very "tubey," rolled-off, and old-fashioned. The internal resistance was only minor compared to external so was "swamped" effectively. Awarded to France in 1930, it is a small, low atoll two miles square lying 685 miles west of Acapulco, Mexico and inhabited solely by wild pigs. 691 likes · 12 talking about this · 1,046 were here. The gain of the cathode follower can be approximated using: mu / (mu + 1). The signal is being introduced at the grid of the first triode, and is mixed with the LO because the LO signal is running the first triode through a non-linear. Below left is the Sweep Chassia. After finished my simple 12AX7 tube preamp, I decided to try other medium mu tubes, including this 12AU7 and also the 6922. Thread Tools. This is a copy of the Hiller transformer that was in the early C12 mics. - 1 x 12AT7 - used as reverb driver - 4 x 6L6WGC - TAD - TAD tubes seem to sound very good with this amp. Because the AC cathode follower is normally used only as a transparent buffer for driving difficult loads, it makes sense to use a. circuit at W9TO. ), the cathode follower can be almost any small signal triode tube - almost, because once you choose the socket and the basing connections, there is little variation possible - 5687 is one example - and of course you have to keep in mind the operating. amp ef 183 balanced modulator 12at7 l,s. This provides much better performance than a cathode follower (all tube) solution. The price we pay for this is gain, which is slightly less than unity. 26 on page 374. To the right is the power supply. You won't know if the tube is doing anything (since it could be a cathode. This receiver was a development of my original 12AT7 battery powered receiver. Petersburg (Winged "C"/SED) tried to develop a good 12AX7 and mostly failed. V2 provides the second of your dirty channel gain stages, and the first half of the cathode follower circuit. Sound stage was just out of the is world! Try to stay with the same type in the chain, but no harm in going with different types for Driver & Cathode Follower. Would buy them again. This receiver was a development of my original 12AT7 battery powered receiver. I subsequently asked about changing the pre-amp tubes in a Mesa Boogie combo amp but never got a reply. The reissue cathode is oblong, with a relatively thin coating. Hiwatt is a British company that manufactures amplifiers for electric guitars and electric basses. 12AT7 VOX amplifier and calibrator oscillator. Re: Best new production 12AX7? Sun, Mar 10, 2013 11:08pm. Each channel consists of a 6AK5 cathode-follower driving a 12AU6 differential pair which drives a 6AU6 differential pair. 12AU7 (ECC82) Cathode Follower Tube Preamplifier Schematic. Unlike the 12AX7 with its 62kO output impedance, the 6DJ8 rarely needs a cathode follower to drive a cable or an output stage. Cathode Follower: 13. This is the key element missing in the Cathodyne Phase Inverter (Fig. The heaters started to glow, and I was getting scratchy output when I probed for voltages. Cathode Follower Output. 5642 drivers 6au6 drivers 6 aus 6au6 ve04 v12 v13 v14 vert. Mar 22, 2017 - 12AU7 / ECC82 Cathode Follower Tube Preamplifier Schematic. I also posted this over at the Amp Garage, but wanted to ask the brilliant minds over here as well: I noticed an annoying little buzz coming at the CF position of a 5F6A. & isolation meter amp 5146 rx r. and this is why it is ideal for directly coupled cathode followers. Rare Pair Amperex PQ 7062 / E180CC. The Cut control allows for fine tuning of the top end with more control than the traditional presence style control. Cx APC air variable. The power section is articulate, punchy, and stays clean at extreme levels of volume. V5 ECC81 (12AT7) 1st AF Amp V6 ECC81 (12AT7) Tx Mixer V7 EL83 (6CK6) Tx Driver V8 QQE06-40 (5894) Tx PA (selected for its excellent linearity) V9 ECC81 (12AT7) 9 MHz Carrier Gen V10 EF91 (6AM6) 5 ~ 5. The tube is a 12AT7 dual triode. The reissue cathode is oblong, with a relatively thin coating. There are differences in how the phase inverter gets the signal. Four pairs of loading plugs are supplied to optimize the resistance for your mc cartridge. To be truthful, I'm not sure what effect a disimilar dual triode would have on this position. A cathode follower (or a high voltage MOSFET source follower) should be used to ensure the output impedance is low enough to drive the external amplifier and the interconnect lead capacitance. It's been a while since I've had a classic amplifier in my system, and McIntosh Laboratory's MC275 is as classic as they come. This worked "fine" but calibrations had all jumped up a bit, but nothing a Philips' trimmer did not fix. Diamond Power Image Dissector Camera Restoration. Broskies Aikido implementation he first came up with from the 1990's he shows in that blog further down where the transformer is involved is exactly what a bunch of us were taking about in vintage tubestalk at that time and quite a few of us did it. This is because we… - ampvalves. CATHODE FOLLOWER. I use 1/2 of the tube for each channel, bias it at the same 10mA. It's a long time since I read the Lipschitz paper, but it was impressed upon us a Decca that RIAA should not be implemented in a "single network", but, to avoid interaction the 318 and 3180µS constants should be buffered between 1st and 2nd stages, and the 75µS later. The GE 6BX7GT was superb as the cathode follower tubes in my SDS headphone amp. The voltage drop there is too great and this tube will not last long there. Sound stage was just out of the is world! Try to stay with the same type in the chain, but no harm in going with different types for Driver & Cathode Follower. But if it was cathode follower, cathode follower stage, or a common cathode stage, I treated it simply as a "hypothetical", as they used to say in the OJ trial. Tube elements 1, 2 and 3 perform as a cathode follower amplifier. It's not vastly different then a 12AX7 but there is better note definition. After a few of these tests I decided to connect the best low cost transformer (Edcor XSE15-8-5K) up to the best low cost sweep tube (6AV5) and drive them with a Tubelab SE board, power the whole thing with a bench supply, and apply a little cathode feedback to help out the smallish transformer. The EQ is also footswitchable. switch cathode follower v 5-6 1/2 12at7 sweep position r 45 voltage 15k c 17 r 46 2. 98, which greatly reduces the output impedance and increases the output force, by adding a deep NFB, the closed loop gain is about 11 and the NFB is 47. The common cathode stage provides voltage gain but, by it's nature, a cathode follower (2'd stage) has no voltage gain; but does have CURRENT gain, which is why it's used when driving loads (like a tone stack or long, capacitive, preamp cables, etc. Definition of "xy-stereo": XY Stereo microphones contain two directional capsules mounted in a “coincident pair” arrangement: physically close, but pointing 90°-135° to one another. 218 is designed to provide demodulation facilities for independent sideband and single sideband suppressed carrier signals, when used in conjunction with the RACAL RA. The Circuit. This provides DC bias for the cathode follower. MM Phono Stage Gain 46dB. 12AU7 (ECC82) Cathode Follower Tube Preamplifier Schematic. It also supplies a near constant current flow shared between the two cathodes--as current increases through the upper cathode the current decreases through the lower and vice versa. You won't know if the tube is doing anything (since it could be a cathode. The effect on the transient response of varying the circuit. a cathode follower is exactly that, the current flowing through the preamp tube using the triodes kind of like a filter, and not a set of gain. After finished my simple 12AX7 tube preamp, I decided to try other medium mu tubes, including this 12AU7 and also the 6922. I doubt this comparison tells you anything without the schematic. (Similar to an NOS 5751 in gain without the price tag). Will the 12AT7 have any adverse effects on the amp? I’m also curious what you guys have been using for V2 on the MAZs’ which had the cathode follower. Plugged a guitar in and she roared to life!. © 1998 - 2014 Eurotubes Inc. The 6C10 is a three-section 12AX7, and the 6D10 is a three-section 12AT7. Tube noise control function, when the tube 845 or 300B make some noise, you can use noise control knob on the top panel to control the tube noise. * PCB is double-sided gold plated, resistance Beijing 718 is coupled to Germany Siemens or ERO. A cathode follower, on the other hand, has very little effect on the actual sound or "tube-ness" of the sound and it's the tube-ness that people generally desire. This circuit. The second gain stage is nearly identical to the input stage and is direct coupled to the third stage which is a cathode follower (12AT7). These are premium 12AT7 equivalents. The material itself is 0. This receiver is a development of the 12AT7 circuit that has been used in numerous receiver designs on this site for the reception of FM in the 88-108Mc/s band. promises made in doing so. v5: Amp and. Cathode follower circuits are said to lend the tone a special flavor, as a number of classic guitar amps would go to show. Also the LED implementation has been changed so it can be switched to ground using a CLR and a 3PDT switch in standard-wiring. R36 is the tail resistor that creates the relatively high voltage (34v DC in the Bassman) needed for the cathode follower function of the upper cathode. My EAR 834P Chinese clone Phono preamp works great with Ei's ECC83/12AX7 and ECC82/12AU7 (as a V3 that is used as a "buffer tube" on a cathode follower configuration), it also likes some Hitachi 12AX7 and 12AU7, and Matsushita 12AX7 and 12AU7. So the charge amp is a way of having cathode follower like characteristics yet it has good noise rejection and has the tubey-ness that people desire. The "CHOP" mode of the 3A2 switches back and forth between the two inputs at a rate of a few kilohertz. Bonus! We can use this triode section as a common-plate (cathode follower) stage. Insanely tweakable, and promising the ability to mimic your own amp, could this be the last word in amp modelling? For any guitarist, there’s a reassuring air of familiarity and class about the Bias Head’s black, grey and silver enclosure, but its front and rear grilles are purely cosmetic — inside lurks a 25-preset, deeply programmable combination of Positive Grid’s highly regarded. 6350 Dual Triode (The best sounding 6350 are Sylvania black plates 1950's followed by GE black plates then RCA) (The 6350 is a very high quality dual-triode. This schematic below is a simple two stage line-level preamplifier using a single 12AU7 (ECC82) tube per channel. Harmonic distortion less than 1%, output voltage 2V. The output stage that drives the vertical deflection plates of the scope uses a pair of 6BA8 pentodes. If the tube grids were driven by a cathode follower that can source the required current, then the blockin would not happen and it would be possible to drive the amp into grid current region. They basically just bypassed the cathode follower. If you put 12at7 in voltage amplification stage of your amp, Try to choose the most transparent ones for current (e. v4: DSB and SSB Audio Amplifier: 6CW4. The original circuit uses a 12AX7 differential amplifier, and half of a 12AT7 dual triode for the output stage for each channel of a stereo system. 00085RLOAD VRMS into low impedance loads. Specifications. I suspected the shielded lead, about 3' long, running from the 12AT7 socket to the amp, had enough capacitance to shunt some of the highs to the amplifier. Perhaps i'll try 5K1 grid resistor instead of 1K5 on power tube in first time. 1 Origins of the Dave Reeves Hiwatt legacy. This is an interesting circuit: the use of a 6U8 tube is questionable, there are better and lower noise pentodes, also this circuit could be done using a. 75-131 mc crystal oscillator V4. There is no reason that you can't use cathode bias in these designs. Insanely tweakable, and promising the ability to mimic your own amp, could this be the last word in amp modelling? For any guitarist, there’s a reassuring air of familiarity and class about the Bias Head’s black, grey and silver enclosure, but its front and rear grilles are purely cosmetic — inside lurks a 25-preset, deeply programmable combination of Positive Grid’s highly regarded. GENERAL ELECTRICAL Series Parallel Cathodeâ Coated Unipotential. Problem is, the cathode follower circuit can easily see 180V, which is right on the ragged edge of the rating for a. The ACF-2 is an All-in-One design that holds both the B+ and heater power supplies and two Aikido-ized cathode followers. 4Vrms, and thus create far to much volume level in most power amps which need only 1Vrms to cause clipping. I have one that uses a 6EA8/6U8 (Audio Preamp), 12AT7 (Cathode follower), and a 6HZ8 (Oscillator/Screen Modulated Final). 12AT7/ECC81 equivalents. Cathode Follower: 13. He took his time, and his attention to detail resulted in a very tidy underside. 12au7 guitar amp partially based on firelfly amp Tyler Richard style preamp with 3 gain stages and a DC coupled cathode follower at the end to drive the tone stack. SVT is DC but need -150V that not easy to build. The common cathode stage provides voltage gain but, by it's nature, a cathode follower (2'd stage) has no voltage gain; but does have CURRENT gain, which is why it's used when driving loads (like a tone stack or long, capacitive, preamp cables, etc. If fixed bias is to be used in the output tubes they must be driven by direct coupled cathode followers. All of this suggests that other than for its lower heater/cathode voltage rating, of all the common small signal triodes, the 12AT7 makes for an outstanding cathode follower, possessing both significant gain, and current handling capability (low plate resistance) to aid in producing a low source resistance. After that the signal is fed to a 1/2 12AT7 as cathode follower. Although the load is at the cathode, a loadline can still be drawn the same way as in the gain stage : I have chosen a steeper loadline as I want to have the cathode to run at higher output current. All Rights Reserved All text and images on this website may not be used without express permission. the SRPP and the µ-follower) Real-world valves The cathode and the work function Getter Commercially available valves Valve envelopes Small signal valves Low-noise pentodes Double-triodes 12AT7 (ECC81) 12AU7 (ECC82) 12AX7 (ECC83) 6072 VF14(M) - the scarcest valve in the. These are premium 12AT7 equivalents. Parameters: PCB Size: 155mmx121mm Features: * Imitated from the famous Marantz 7 (Marantz) classic circuit. Taking off the 6. and this is why it is ideal for directly coupled cathode followers. It comes real close to the 5842's performance. The return of the multivibrator to the normal state is de-. 0032″ thick. The NBS line stage has the identical 6H30 single stage AF amplifier circuit as the phono preamp on one set of outputs and an added 12AT7 cathode follower low impedance output on the second set of outputs for driving long cable runs or low input impedance amplifiers. When they are set up as cathode followers, the cathodes can see 150 to 200 volts depending on the design. Conclusion: good gain, but its too entitled to my opinion. Also there are some pretty common designs that use the 12AT7 to drive a reverb tank. 00 USD; Bass Normal Gain $58. C11 is a non-polarized, metalized polyester film capacitor, which is located across the high voltage transformer secondary, suppresses EMI frequencies from 20kHz to 30mHz. These are dual triode tubes, the 12AX7A having replaced the 12AT7 as a better tube. C, Level Control 2 6CB6 -|-Gate Oulpul Cathode Follower Vi 1 2AU7 Astigmatism Potential Cathode Follovrer. ECC832/12DW7/7247 – Dual AF triode, a combination of one ECC83/12AX7 system for use as a high-gain amplifier and one ECC82/12AU7 system for use as a phase inverter or cathode follower ECC960 – Common cathode, dual triode for use as a flip-flop in computers. The 12AX7LPS also has a spiral filament for reduction of heater to cathode induced. Define cathode beam, cathode ray. As a simple anode follower, the 12AU7 / ECC82 often finds itself as the last stage in preamplifiers or as a driver for parallel-pair output stages. In that case the plate resistors must be beefy enough to take them, and there are no cathode-follower positions, so you're OK. V3 is the phase inverter. Mine lasted about 10 minutes. Popped in 12AX7s in V1 and V2 (which is just the cathode follower now), and the 12AT7 in the new socket. Transformer Balanced Out: For superb professional quality direct recording. Now, if the tube is there for decoration, or it's a cathode-follower circuit, the gain reading won't change. ef 9j driver 6ch6 ist rx mixer 6 be6 ist. Therefore the use of a shunt NFB network using R3 and R8 is needed to reduce overall gain at maximum volume setting = 1. The output impedance of your Fosgate Signature is low enough to drive solid state preamps down to a 10K input impedance. 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. The power amplifier is driven by a conventional long-tailed pair 12AX7 phase-inverter stage, followed by a 12AT7 cathode-follower stage to provide a low impedance drive to the sextet of 6L6GC output valves. The original topology was a Williamson-type amp with the typical rotary input selector switch, Bass, Treble and. The Shrimp can drive anything, not to worry. 27mA dc current drawn by the output cathode follower allows it to source roughly 0. But the 12AT7 and 12AU7 are rated for a max of around 1/2 that. Blue Logic Electronic Repair And Warranty Service Center, Gympie, Queensland. Frank Van Alstine tells me that this circuit was initially evaluated as far back as 2004 and was put on the back burner because it failed to provide the. The return of the multivibrator to the normal state is de-. 2 x 12AX7 + cathode follower (IRF820 source follower). V3 provides the second half of the cathode follower circuit. , including R6, C6, R9, C7). cathode follower mic key 1 6146 6ch6 12at7 12at7 6am6 ef183 12at7 2xs35 12ax7 12at7 12au7 ist. , Marshall)? Seems to me the 12AU7 side would work well in the buffer part, leaving the gain stage more or less unchanged. Starting in the late 1960s, together with Marshall and Vox, Hiwatt contributed to the sonic image popularly termed "British sound". Tyrosine? Yes, I think so, then some Zappa Valley Girls, Oh I am sure! Thatch. ) Using the 1 to 10 step up, this would result in a 10000 Ohm output impedance. Cathode load resistor = 300V / 3mA = 100k ohm. New to the world, so just learning my way around. The circuit posted is a common cathode (1'st stage) stage feeding a cathode follower (2'd stage). If you're looking to tame a first gain stage that's a little raw and hairy and needs some tightening up, the right 12AT7 might be just the trick. Now with a 12AU7 I'd expect '-8' or '-4' with the lower gain tube. The signal is further amplified by the traditional 12AX7 powering the JMT 5 cathode-follower tone stack. There are three possibilities for the part of the circuit unit between the input 'and' gate and the output cathode-follower, namely a digit delay (half a 12AT7 valve), an inverter (half a 12AT7 valve), and a direct connection. I tried it in a line preamp, a headphone amp, as output stage in my CD player and in several guitar applications with good results. My EAR 834P Chinese clone Phono preamp works great with Ei's ECC83/12AX7 and ECC82/12AU7 (as a V3 that is used as a "buffer tube" on a cathode follower configuration), it also likes some Hitachi 12AX7 and 12AU7, and Matsushita 12AX7 and 12AU7. The design is exactly the same as the 12AX7 preamp, it is a single gain stage triode tube with cathode follower. Perhaps i'll try 5K1 grid resistor instead of 1K5 on power tube in first time. The Sovereign’s first input-stage tube is an EF86 (a pentode similar to an EL34) that is like having a miniature power tube in the first amplification stage. Tube preamps for phono, bass, guitar, mic, so are descibed in function and how sound works. why low rp tubes and cathode follower circuit work for preamplifier output stage 왜 프리앰프 출력단에는 낮은 플레이트 내부저항을 가진 진공관이 필요할까요. 0: 6AS7G(2) 3: 2A3 Single Ended cathode follower drive amplifier: What's with the background of this web page? Cathode Follower: 19. 048″ wide on the larger. A further improvement was made by using an active filter for removing the quench frequency. Without 12AU7*2+12AX7*2 Tubes , please Note. El-84 Power Tubes rather than 6L6 or 6V6 tubes. The grounded cathode inverts while the cathode follower doesn't. Because the capsules are close together, the mic should produce no phasing problems in the stereo signal, which in turn means that the stereo signal created. I tested all combinations with NOS GE 12AT7, EI 12AX7 and JJ/Tesla 12AX7 and I noticed that 12AT7 as cathode follower gives about twice volume compared to 12AX7. I tried it in a line preamp, a headphone amp, as output stage in my CD player and in several guitar applications with good results. The two channels converge on a 12AT7 cross-coupled cathode-follower. Tubes are identical construction, made at the Amperex Heerlan Plant. I used 12AT at second position for a few months but I finally settled with JJ/Tesla at first position and EI at second (I heard that JJ’s don’t last long when used as cathode. 25VRMS: well above the 1VRMS. The remainder of the tube is a plate detector, the cathode of which is common with the cathode follower amplifier. 5 MHz VFO V11 ECF89 (6U8) VFO Bandpass Buffer/Cathode Follower. Past all that, I'd look to adjusting the plate loads of the gain stages or their. A lot of this is down to the harmonics, generated by the cathode follower stage, that enrich the output signal. It is mains powered, with a loudspeaker, and does not use reflexing. View as Grid List 8 Items. v3: Audio Output and Detector: 6AL11. the other thing you need to know is that theres 2 more common ways of running a preamp tube. Circuit of the receiver. Section 1, which is similar to one section of a 7025, is intended for application in low-level, high-gain stages where low hum and microphonism are desired. All Rights Reserved All text and images on this website may not be used without express permission. Therefore the use of a shunt NFB network using R3 and R8 is needed to reduce overall gain at maximum volume setting = 1. KWS-1 CIRCUITRY. And not used in cathode follower position!. Wanted to ask, on v2, the Cathode Follower, seems to not like tubes with spiral filaments. New revision allows White-cathode-follower configuration. I have Sylvania JHS 12at7 as a driver and Amperex 7062 as Cathode Follower and love the results - your results might vary. (12) Using a 12AX7 as a CF is a dumb idea. In the DC cathode follower, the CF's grid is connected to the previous stages plate, so is sitting at well over 100V This creates grid conduction at the CF's grid (it becomes forward biased like a diode) and this pulls current down through the previous stages plate. I'd recommend 12at7. Svetlana 12AX7 - For several years the original Svetlana 12AX7 tube from St. rx mixer 6be6 2nd. Also there are some pretty common designs that use the 12AT7 to drive a reverb tank. We need a balanced dac DC to first valve circuit. The tube is a 12AT7 dual triode. Properly deployed, I find the 6SL7 to offer a more dynamically nuanced presentation than the 12AX7. 12AT7: B152, B309, B739, ECC81, ECC801, ECC801S, E81CC, M8162, QA2406, QB309 The upper tube also acts as both a cathode follower and as a constant-current source. Also you sometimes see it or a 12au7 driving a tone stack or using one of the triodes as a cathode follower. , RIAA phono equalization) feedback network (e. Cool White-follower output stage provides low 50 Ohm output impedance. The camera has its own count-down sync generator, with both video and RF output. 98, which greatly reduces the output impedance and increases the output force, by adding a deep NFB, the closed loop gain is about 11 and the NFB is 47. It's the exception to the "Don't use Russian 12AX7 tubes in a cathode follower circuit" rule. With the 11 volt bias the tube draws around 1. One 12AT7 is a push pull bootstrapped voltage amplifier; the other 12AT7 is a cathode follower driver for two KT88 outputs connected in push pull. So, I will ask again: The 5 "pre-amp" tubes in the Boogie are: #1: 12AX7 - Input stages and tone controls. The plate follower (a. Thus, for example, when the level at the input is increased by 100 volts, the plate and cathode of VI both rise b,. 7Mc/s signal from the VFO and then with the output of a crystal controlled oscillator to produce the. This effectively acts as a second footswitchable volume control, and allows boosting the signal when desired. Cathode Follower: V1A, the triode section of the 6AW8 tube is wired as a simple cathode follower. Low plate resistance tubes give low output Z , and while not many can get much below 1K ohm they can do a good job , with a little or no feedback. V2 and V3, also RCA-12AT7's, are cathode coupled multivibrators operating at 100 Kc and 10 Kc, respectively. V12 V13 V 14 V18 V19 V20 V21/ V22 DI 1)2/5 6BA6 6AM6 6AL5 6489 12AT7 12AT7 6BE6 12AU7 6AM5 6AM5 OB2 IOOSC2 DD006. This provides DC bias for the cathode follower. The designer counters the bandwidth problem by coupling the plate of the pentode directly to the grid of the suceeding cathode follower and then employing considerable negative feedback. 6V (in need of replacement components) The LITE CT3 MM/MC. Early Fender Bassmans, the Marshall JTM and several Vox amps were all. Above is the "schematic" of one channel of the Amplifier/Buffer PCB ~ V1a (pins 1-3) is the gain stage with the cathode resistor R30 not bypassed so it provides (acceptable) local negative feedback which reduces the distortion and increases the effective value of the triode internal anode resistance from r a to r a + µR k + R k. a cathode follower output. This schematic below is a simple two stage line-level preamplifier using a single 12AU7 (ECC82) tube per channel. Tried V3 (cathode follower position), it was super weird electrical noise, even at zero volume master! I quickly removed. At the same time, at audio frequencies, the valve works as a cathode follower (with gain of about 0. switch cathode follower v 5-6 1/2 12at7 sweep position r 45 voltage 15k c 17 r 46 2. All clean and neat. I typically use Tung Sols in the first preamp stage because they have a warm sound. Should I go for cup number 2? Maybe some Ribose and Royal Jelly. The Long-Tail Pair. The first stage wired in cathode follower gives a large input impedance and modulate the second stage wired in µ follower which gives the amplification and the low output impedance. In theory, with a big enough output cap and 300 plate volts, this SHOULD be able to drive 600 ohm headphones to a very high level. The two channels converge on a 12AT7 cross-coupled cathode-follower. Triad transformer isolated balanced output (600Ω impedance) with +6dBu gain allowing direct connection to mixing. The Oscillator. This is the key element missing in the Cathodyne Phase Inverter (Fig. 00085RLOAD VRMS into low impedance loads. It's easiest for us to make a VCO by varying the sensitive grids of our 2D21, so we will drive it with a cathode follower made from half of a 12AT7. For the follower try 680 Ohm on the cathode, a. and this is why it is ideal for directly coupled cathode followers. The Vackar series-tuned v. Class-B operation creates crossover distortion. Non-inverting two-triode gain stage is direct-coupled for most pure signal path. 3 pF and out with. The absolute phasis is observed. Broskies Aikido implementation he first came up with from the 1990's he shows in that blog further down where the transformer is involved is exactly what a bunch of us were taking about in vintage tubestalk at that time and quite a few of us did it. Without the ECC99 it would not be possible for the 12AT7 to produce sufficient current to properly run 4 KT90’s. Instead the 355 provided a cathode follower, line-level, preamp out -- Just add the basic power amp of your choice, usually a Scott Type 208, but Mac's and Dyna's were also popular choices. For a common tube Out+ such as ECC88, for example, Z will be approximately 100-200Q, a much more attractive figure than even the ex- otic differential amplifier. V3 is the phase inverter. Properly deployed, I find the 6SL7 to offer a more dynamically nuanced presentation than the 12AX7. GENERAL DESCRIPTION Technical Summary. The cathode follower stage uses its very low impedance to drive the tone circuit, but it also contributes a lot to the distortion. That's with a 12AT7. My EAR 834P Chinese clone Phono preamp works great with Ei's ECC83/12AX7 and ECC82/12AU7 (as a V3 that is used as a "buffer tube" on a cathode follower configuration), it also likes some Hitachi 12AX7 and 12AU7, and Matsushita 12AX7 and 12AU7. 00085RLOAD VRMS into low impedance loads. amp with 12AT7 power. The 12AU7 and 12AX7 have a 180 volts limit. 3 Another sample circuit in principle --- P-G NFB'ed cathode follower drive The auther tried to explain the difficult STC V1 circuit directly by Rev3. an E82CC is a special quality version. Although maybe for hi-fi. The common cathode stage provides voltage gain but, by it's nature, a cathode follower (2'd stage) has no voltage gain; but does have CURRENT gain, which is why it's used when driving loads (like a tone stack or long, capacitive, preamp cables, etc. the output cathode follower would slightly reduce this to 1. The breaker automatically resets after a few minutes. Specifically, in a 12AX7 tube used as a "cathode follower", the voltage difference between that present at the cathode, as compared with the heater voltage, can be withstood or tolerated by certain types of tubes, whereas other tubes will fail. 72, or only 0. Your guitar signal is A. cathode-coupled) amplifier I am a big fan of the common-cathode amplifier (also known as the “cathode-coupled” or “grounded-grid” amplifier—no thanks to Bruce Rozenblit, whose taxonomic howler has made already murky waters murkier still). Cathode Follower Calculator Basic Theory - using 21st-Century technology to design vacuum tube preamps, power amps, and power supplies System Design - a professional methodology for crafting a complete guitar amplifier. I've decided to relaunch my most popular seller with many upgrades while still keeping the price under $1K. GM3WOJ: ZL1CT: Vintage : transceivers: valve/tube: information: Collins: KWM-2A: Hallicrafters: SR-150: Drake: TR-4C: National: NCX-3: Swan: 350: Swan: 350-C: Yaesu. Section 1, which is similar to one section of a 7025, is intended for application in low-level, high-gain stages where low hum and microphonism are desired. V3 cathode resistor 2. The current production Svetlana is a New Sensor product and is a member of 12AX7-EH and Tung-Sol 12AX7 family. 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. The Marshall DSL40C (and DSL40CR) use 3 x ECC83 (also called 12AX7) preamp valves, 1 x balanced ECC83 in the phase splitter position (V4) and 2 x EL34 matched power valves. senx preamp. Four more tubes, a 6AL5 and three 12AT7's, comprise a logic circuit which determines which channel drives the output at any given moment. A further improvement was made by using an active filter for removing the quench frequency. 72, or only 0. theres also emitters, but i wont go there. Mains Operated 12AT7 Super-Regenerative Receiver for 88-108Mc/s FM. Residual THD is less than 1% just before clipping. The driver is cathode-keyed. Insanely tweakable, and promising the ability to mimic your own amp, could this be the last word in amp modelling? For any guitarist, there’s a reassuring air of familiarity and class about the Bias Head’s black, grey and silver enclosure, but its front and rear grilles are purely cosmetic — inside lurks a 25-preset, deeply programmable combination of Positive Grid’s highly regarded. I typically use Tung Sols in the first preamp stage because they have a warm sound. Page 9: Powering Up Settings: Refer to the information sheet for your phono cartridge to determine the output voltage specification and the recommended cartridge resistive loading setting or range. Broskies Aikido implementation he first came up with from the 1990's he shows in that blog further down where the transformer is involved is exactly what a bunch of us were taking about in vintage tubestalk at that time and quite a few of us did it. I also used a direct-coupled cathode follower 12AT7 after the 12AX7 phase inverter to really drive the power tubes - similar to the old SVT bass amps. Air Tight's Single-Ended Triode Power Amplifiers ATM-300 30th Anniversary Version. 6EA8 Speech Amplifier and cathode follower. The circuity use five tubes as ECC 88/6922 for moving coil and two ECC-81/12AT7 for moving magnet (as passive riaa equalization) and one ECC-81/12AT7 for output as cathode follower adaptor, all tubes are accurate selected at very low noise operation. Double-sided gold-plated PCB LSDY tube voltage stabilizing circuit power PCB ARC tube voltage line 6Z4 rectifier tube 12AT7 as a voltage comparator 12B4A as voltage adjustment, adjustable voltage from 150V ~ 400V, with a group of filament voltage, output voltage of 6. The design is exactly the same as the 12AX7 preamp, it is a single gain stage triode tube with cathode follower. Great first impression. The driver stage is constructed around a 12AT7 (phase inverter) and a ECC99 (cathode follower buffer stage). The low filament-to-cathode voltage rating means that you should not use these in a cathode follower circuit. A cathode follower (or a high voltage MOSFET source follower) should be used to ensure the output impedance is low enough to drive the external amplifier and the interconnect lead capacitance. I wanted to use SuperReverb cathode follower to prevent blocking distortion on 40W amp to maximize clean headroom. With a FM stereo output, the cathode followers perform separately as left and right channel output stages; on monophonic AM or FM, the two output stages are tied together and supply the same information to both. The gain is foregone for 0 , 6 , 10 , 14 and 20dB. All that chrome offset by three-shinny black painted transformers, the old English style lettering on the front and four KT88's had looks to die for. Mar 22, 2017 - 12AU7 / ECC82 Cathode Follower Tube Preamplifier Schematic. What is the plate voltage? Hellhound: 450v. The circuit posted is a common cathode (1'st stage) stage feeding a cathode follower (2'd stage). The output stage of the circuit is a Cathode Follower and is suitable to drive a low impedance amplifier. 10 Profiles. The common cathode stage provides voltage gain but, by it's nature, a cathode follower (2'd stage) has no voltage gain; but does have CURRENT gain, which is why it's used when driving loads (like a tone stack or long, capacitive, preamp cables, etc. SLO 470pf/47k tonestack. 2521 is used. Audio by Van Alstine FET Valve CF Vacuum Tube Preamplifier Review Highlights. ) Using the 1 to 10 step up, this would result in a 10000 Ohm output impedance. 98, which greatly reduces the output impedance and increases the output force, by adding a deep NFB, the closed loop gain is about 11 and the NFB is 47. The power supply is a cost-no-object design:dual mono, separate chassis, two tube plate regulators per channel, ample filtering, star grounding. When they are set up as cathode followers, the cathodes can see 150 to 200 volts depending on the design. 0: 12AX7: 5. The ultra - linear follower drivers for class X2 operation. Mar 22, 2017 - 12AU7 / ECC82 Cathode Follower Tube Preamplifier Schematic. 6EA8 CW side-tone oscillator and amplifier. Avoid these in high voltage cathode follower (CF)spots. Put both pairs of your old tubes in and listen for a while to get a good handle on the sound. I typically use Tung Sols in the first preamp stage because they have a warm sound. The plate follower (a. Asking $20. McIntosh C2200 Amp Reviewed By HomeTheaterReview one 12AT7 is a push-pull bootstrapped voltage amplifier, and the other is a cathode follower driver feeding four 6550/KT88 outputs tubes in. Kingsnake: 495v. It splits the signal by virtue of the fact that the signal appearing at the cathode of the tube is in-phase (this circuit by itself is called a “Cathode Follower”), while the signal at the plate is out-of-phase (this is a typical Common-Cathode amplifier). Bruce used Gold Pin JJ ECC83S for the SRPP stages and half of a ECC81 for each side of the cathode follower. v5: Amp and. Many audiophiles discount it instantly, believing that it is a sonic blight. With a twin triode, V2a and V2b will be balanced, and the output will rest at B+/2. Section 2, which is similar to one section of a 12AU7, is intended for cathode follower or phase-inverter service. The 12AT7 projects horizontally from the b. Projděte si naše materiály o tom, jak tuto situaci zvládnout. The 6C10 is a three-section 12AX7, and the 6D10 is a three-section 12AT7. 10 update stage, the auther found a another sample that seems to be easier way to explain the STC circuit. It's output feeds the tone stack and the treble pot feeds the phase splitter(V3). The Independent Side Band and Fine Tuning Unit type RA. It's easiest for us to make a VCO by varying the sensitive grids of our 2D21, so we will drive it with a cathode follower made from half of a 12AT7. 0: 6U8, 2A3: 4: My first tube amplifier: Intended for use as a separate state to have around for radio use. The tube that most affects the sound is the tube that should have the least affect, the 6922 (6dj8), which is used for a cathode follower. The circuitry utilizes five tubes — two tubes (ECC88 / 6922) for moving coil cartridges, two ECC81 / 12AT7 tubes for moving magnet pick-ups and one ECC81 / 12AT7 for output as a cathode follower. The small shield can in the far right corner has been replaced by the 6C4 cathode follower, V4, since the photo was taken. Even with an extremely low load of 5k (driving two power amplifiers, each with a low 10k impedance: a worst case for biamplified speakers), the PAS can put out 4. v3: Audio Output and Detector: 6AL11. Will the 12AT7 have any adverse effects on the amp? I’m also curious what you guys have been using for V2 on the MAZs’ which had the cathode follower. anode follower), like the common-cathode amplifier, is a much-too-overlooked circuit. It looks like a Cathode-Follower Circuit. Cathode resistor sets the current to be nominal. 6EA8 Speech Amplifier and cathode follower. Svetlana 12AX7 - For several years the original Svetlana 12AX7 tube from St. cathode follower). Bottlehead Crack by Tim U. I've used Mullards for gain and RCA Cleartops as followers. The 12AT7 is a high-mu twin triode on a 9 pin base. Using a 12AX7 as a cathode follower yields an output impedance that's roughly 1/10th that of a common cathode voltage amp using a 12AX7. Cathode Follower: 13. Double-sided gold-plated PCB LSDY tube voltage stabilizing circuit power PCB ARC tube voltage line 6Z4 rectifier tube 12AT7 as a voltage comparator 12B4A as voltage adjustment, adjustable voltage from 150V ~ 400V, with a group of filament voltage, output voltage of 6. The amplifier output is directly cou-pled to a buffer that uses 1/2 of the second 12AT7. Residual THD is less than 1% just before clipping. NOS JAN ECC83/12AX7s are recommended for this position. This is the key element missing in the Cathodyne Phase Inverter (Fig. It is especially suited for use in resistance-coupled voltage amplifiers, phase inverters, multivibrators, and numerous industrial-control circuits where high voltage gain is desired. Circuit of the receiver. No additional filters. 5abp1 block crx diagram v208b —gate v222 4-3-53 6cb6 6j6 unblanking floating power supply 12au7 *'ate v215 6z7 trigger cathode follower vert. Also the LED implementation has been changed so it can be switched to ground using a CLR and a 3PDT switch in standard-wiring. peace and good luck!. Hybrid Tube/solid state rectifier system provides the stability of diodes with the smoothness of a tube rectifier. Since in a lot of cases 12at7 is used in current amplification circuits, it has very little to do with gain (mu), so gain here is not relevant and theoretically 12au7 & 12ax7 could be used in place of 12at7. The Independent Side Band and Fine Tuning Unit type RA. The effect on the transient response of varying the circuit. The TILT EQ section was a passive R-C circuit after the 12AT7 EQ stage and before the final paralleled 12AT7 Cathode Follower output buffer. 218 is designed to provide demodulation facilities for independent sideband and single sideband suppressed carrier signals, when used in conjunction with the RACAL RA. Cathode Followers The poor cathode follower; it gets little respector too much. The plate follower (a. cathode follower van 1'2 f2at7 9 r 21 100 2 2qov r22 meg sweep freq. In cathode followers, there can be substantial DC and signal voltage across a cathode resistor, but in this case, the resistor is driven by the low impedance of the cathode, and the voltage across the resistor is controlled by the grid voltage very tightly, so the exact resistor value doesn't matter much - there won't be significant distortion. But the 12AT7 and 12AU7 are rated for a max of around 1/2 that. 25VRMS: well above the 1VRMS. The Sovtek 12AX7LPS has a large plate format that gives a large soundstage with a lot of detail. El-84s are great tubes but sound little like the 6V6 or 6L6 found in most vintage Fenders. 6GW8 Audio amplifier and audio output. It is also at its best, when used as a cathode follower. The Czech engineer Jiri Vackar introduced the design in 1949*. 12au7 guitar amp partially based on firelfly amp Tyler Richard style preamp with 3 gain stages and a DC coupled cathode follower at the end to drive the tone stack. Graphical analysis of White cathode followers Reply to Thread. OK, I hunted down the schematic and V4 is not a cathode follower and is indeed just a standard plate follower. Meter Control/AF Amplifier CW/SSB Detector Line/Monitor AF Amplifiers Monitor Output Line Output Voltage Stabilisers Variable Capacity Diode (BFO) HT Rectifier (silicon diodes). the output cathode follower would slightly reduce this to 1. But the 'Top 40' player needs a little more, and using. The 355 added true FM-MPX stereo reception utilizing the 350/335 decoder design, incorporating the "Stereo Guide," 6AV6 tube indicator. You won't know if the tube is doing anything (since it could be a cathode. The effect on the transient response of varying the circuit.