This is actually the anode to cathode voltage, so the true cathode voltage will be 285 - 100 = 185V. In 1963 "graphical methods" meant drawing Bode plots with a pencil and ruler. You aren't looking for gain, you want a current source so they are the obvious choice. A 12AU7 or 12AT7 will perform better under those conditions. 1/gm. Its submitted by government in the best field. Unfortunately when I connect the cathode follower into the circuit it . V2 is controlled by the injected 1 -Mc signal from the crystal, and is synchronized at the proper sub -har- It has poor high impedance output current. Cathode Follower Calculator. This is true. A 12at7 in most cathode follower circuits is a bad idea. Better yet, 5687 or 7119! Gain 8,6 Here are a number of highest rated 12ax7 Cathode Follower pictures upon internet. A 12AU7 can take a much higher amount of plate current than a 12AX7 so by substituting the "12AU7" side, you increase the gain and lower the headroom, and an SVT already has TONS of gain. The ACF-2 is an All-in-One design that holds both the B+ and heater power supplies and two Aikido-ized cathode followers. 12ax7 have no bypassed cathode resistor. It's better than a 12AX7, but not as a good as a 12AT7. It's a poor choice for gain as it doesn't have nearly as much. . The Manley Lab Series Line Preamplifier was built from 1994 to 1998.At a retail price of only $1150 it was a simple entry-level unit. But the cathode follower also reduces the loss imposed by the tone circuit, so overall signal level is probably increased by using the cathode follower. A 12AX7 is rated for a maximum of 180V. System I is a cathode follower that feeds the signal into the cathode of system II. If you heat the socket leg with a soldering iron you can pull them off ground 1 by 1. 12ax7 Cathode Follower. 12AT7 Heterodyne oscillator and cathode follower. Re: "not to be used in cathode follower". . There are simply better choices. 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. 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 input to the grid comes through a 100pF cap. V2 and V3, also RCA-12AT7's, are cathode - coupled multivibrators operating at 100 Kc and 10 Kc, respectively. I hope you enjoy the images. - 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? That is why two tubes that have differing amplification factors, like 6AS7G and 5998, produce roughly the same volume with the same driver tube in . They don't affect it significantly, not like the preamp tubes, but as soon as I remove Telefunken 12at7 and replace them with RCA 12at7 black plates or Raytheon 6414 black . The failure of a "cathode follower" tube will cause sound dropouts or signal loss. After that, the signal hit the attenuator, (it went to up to 13) and then into a 12AU7 cascaded stage before hitting the final 12AT7 cathode follower output stage which provided an unbalanced output via XLR and RCA jacks in parallel. 12AU7 Sideband oscillator. Signal source generator 600 ohm. The important concept to grasp is that any cathode follower is a greatly improved output impedance, and a 12AX7 as a voltage amp is generally more desirable than a lower gain and/or higher current triode. Of course, we now use the term SEPP for the more specific circuit arrangement by Peterson and Sinclair. Jim Marshall crafted guitar amplifier masterpieces without the assistance of computers, software or the Internet. The classic Fender amps for instance. The pulse is also fed to the grid of the reversing amplifier (second half. You can use a 12at7 there too. The circuit posted is a common cathode (1'st stage) stage feeding a cathode follower (2'd stage). The output from the second stage of audio amplification passed into a cathode follower audio buffer stage. The glowing filaments and grids of tubes are a sight not often seen in today's transistorized world of amateur radio. 12ax7 plate impedance -120k around. My point is that the RCA and Sylvania tube manual specify close to 300 volts of cathode/heater differential, which it's doubtful any guitar amp exceeds. This is the maximum voltage that the valve can see between the heater and the cathode (known as the "heater-cathode voltage"). My plan is to replace all RF/IF/oscillator/mixer tubes that affect alignment with fresh ones before I perform the alignment and keep the original ones for audio part (one 12AX7 and one 12AT7). A simple cathode follower is shown in Figure 4A.13. SSS Cathode Follower: 12AX7 vs 12AU7 vs 12BZ7 vs 12BH7 Post by Bombacaototal » Thu Nov 03, 2016 9:18 am I am wondering what is everyone's opinion about which one does the best job as a post PI cathode follower driver for the output tubes: 12AX7 vs 12AU7 vs 12BZ7 vs 12BH7 On that note, a 12AU7 really doesn't make a very good cathode follower. But the 12AT7 and 12AU7 are rated for a max of around 1/2 that. 12au7 ecc82 cathode follower tube preamplifier schematic, 12au7 tube preamplifier circuit wiring diagrams, 12au7 tube preamplifier electronics diy, 12au7 tube tremolo h amp g amplifiers, diy 12ax7 tube preamp shine7 audio diy page, xiangsheng 728a 12at7 12au7 tube preamplifier hifi exquis, 5e3m deluxe micro © We identified it from trustworthy source. This is essentially a push-pull stage with the upper triode being used as both a cathode follower and as a current source for the triode below. You will end end up with a rotten sounding amp unless by chance it happens to work and even then it will sound much worse than fitting a 5751. This is a crystal controlled oscillator and two crystals are used, one for USB and the other for LSB. Can you tell if there's a reverb transformer, or have photos of the insides of the amp? the gain stages of the circuit are 3 (in my view) V1=12ay7 + V2=6N2P + V3=6ak5, the following tube V4=6N2P has "no" gain as it is a CF. I'm hoping if I can't get the various stages working as I envisage, I've enough valves to perhaps be able to change types and circuit . why use a 12ax7 for a Cathode Follower when a 12au7 or even a 12at7 is more suited Because the stage feeding it require a 12ax7 triode. Grade 2 (higher than average microphonics) Not recommended for V1 but good for phase inverters, cathode followers, tremolo tubes, $25.00 Taxonomy upgrade extras: Catalog's Front Page You don't want to know what I really think of 12AU7s (or 12DW7s) . 6 2. The east block version is labeled ECC832. 12AT7 VOX amplifier and calibrator oscillator. You can sub a 12AU7 in the cathode follower buffer spot with no changes to the circuit. The VFO uses a 12AU7, the 2 nd section as a cathode follower. Based on the schematics, on of them in each channel is for driver stage and the other one is for cathode follower. Common-cathode amplifier design ideas Although not that popular, the common-cathode amplifier is one of my favorite tube circuits—with good cause, as it offers low input capacitance, low distortion, no phase inversion, and two inputs, the second of which can readily accept feedback from the output or a sampling of power supply noise, to null the noise at the output. I have three pieces of gear in which the 12AT7 is part of the power supply and has no discernible effect on the sound. Popped in 12AX7s in V1 and V2 (which is just the cathode follower now), and the 12AT7 in the new socket. I frequently use a 12DW7, with elevated heaters,which is one 12AX7 triode paired with one 12AU7 triode. It might be 0.8 or so. TABLE OF CONTENTS Paragraph Page I. 12AT7 Heterodyne oscillator and cathode follower. cathode follower. A: Yes, it is equipped with two new JJ tubes which we've found to be the most durable for the cathode follower position in amplifiers. GENERAL DESCRIPTION Technical Summary . However, keep it in. If you are using this in the preamp stage, the gain will be about ≈21v/v or 26.5 dB with a unbypassed cathode and ≈33v/v or 30.4dB with a bypassed . Hence the input has very high impedance, determined only by the volume control (or grid resistor). The cathode follower has a voltage gain of slightly less than unity but it does have current gain which means it qualifies as an amplifier because it increases the power of the input signal. The ECC99 is a power triode that delivers big currents at low impedance, ideal for KT88, KT90 and 6550 tubes. If its a standar rectifier v4 is for fx loop/ cathode follower, as long you take a nor russian 12ax7/ecc83 it will be fine (russian tubes have issues in that place working as cathode follower). 12AX7 vs 12AT7 vs 12AU7: Differences Explained. Basic Principles . The 12AX7 has a gain factor of 100, while the 12AT7 has 60. 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. Also there are some pretty common designs that use the 12AT7 to drive a reverb tank. The gain of the cathode follower can be approximated using: mu / (mu + 1). The "ideal" cathode follower operates at unity gain, a gain of 1, in reality it is less than one, so you actually lose some gain from a cathode follower. But . 12ax7 Cathode Follower. The glowing filaments and grids of tubes are a sight not often seen in today's transistorized world of amateur radio. 1 volt at the output, so we would need 2.72 volts in, for 1 volt output. Problem is, the cathode follower circuit can . I dug through all my notes, read several manuals on tubes, searched the web, rattled the old brain and came up with everything I needed for my design. 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. Mode1: Ef86-12ax7-6072+cathode follower-12at7+cathode follower-KT66. We say yes this kind of 12ax7 Cathode Follower graphic could possibly be the most trending topic behind we portion it in google gain or facebook. However, by the 1990s we suddenly 1983 Fender Concert Amp-Handwired This beautiful 1983 Fender Concert has been tastefully restored and modified. - Jsawyer09 19:41:37 09/04/19. output stage. There is no point in me making an extra socket simply to use half a 12at7/u7. 12AU7, Amplification Factor = 17 . Ehien As of 7/8/21, we now ship with one 12AT7/ECC81 in the first position and 12AX7/ECC83 in the second position. 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. From the 1960s onwards a variety of transistor versions appeared 12,13,1415, but still without the name SRPP applied. 일본 . The Aikido-mojo resistor and capacitor are still in place with the 430k feedback resistor and the 1µF capacitor. catalin gramada. Like all JJ tubes, it has a rugged construction that doesn't compromise the sound of your amp. PCB is in symmetrical for two channels, Can be separate if you want. . As mentioned above, these units had an additional first amplifying stage using a 6072 in cascade. Another objection to the 'X7 triode as a CF is low plate current. The O/P impedance of a CF is approx. V3, V6 (12at7) - output tube drivers, V4, V7 (12at7) - Cathode followers. 6 3. presence of the cathode follower Ir, which drives the plates of Vl and V, with a signal very nearly equal to that at the input. They make a sweet clean gain stage when looking for only a gain of 10. 4 1. Hi John, You are completely correct, if you had the 'AS7 plate loaded. Its popularity over the past decade or so has given it considerable momentum going . It has the same characteristics of the 12at7 and can handle the heater-cathode difference. Just to add, a 5751 is great too. why low rp tubes and cathode follower circuit work for preamplifier output stage왜 프리앰프 출력단에는 낮은 플레이트 내부저항을 가진 진공관이 필요할까요. It's not clear how much sonic effect it imparts. Light came on, no magic smoke and I was getting B+ to the new tube. The rx mixer is a 12AT7 (in a "Pullen" configuration), IF amps as noted, 12AT7 product detector, 12AX7 AF preamp & AGC amp, 6AB8/ECL80 AF o/p. The problem would seem to be the "maximum heater relative to Cathode, negative Voltage" in the case of the 12AX7, this is rated at, in many peoples eyes optomistic, 180Volts. (12) Using a 12AX7 as a CF is a dumb idea. It is a "Rivera" era Fender Concert, the very last Fender-made hand-wired amps with 60 watts of all tube power and tube-driven reverb and FX loop. The biggest difference between these power tubes is the amount of gain they will provide. A follower is a unity gain configuration, the 12Ax7 is a high mu (gain) tube. (50k- bypassed cathode) I will connect the generator directly to 12at7 input to see if matter. . But if it was cathode follower, and the load voltage was in series with the input voltage, then 1.72 volts between grid and cathode would still be needed for. The Bassman cathode follower has according to the schematic, 215 Vollts on the cathode, minus your 6.3 heater, still leaves you in excess. - Timbo in Oz 02:04:46 09/09/19 (1) RE: Using a 12AX7 as a CF is a dumb idea. I just checked, bypassing with 100u did not do any difference. Input tube is a UHF twin triode ECC 81 (12AT7), operating in single-ended differential mode. The tube diagram shows the 3-12AX7's and the 12AT7 at the right rear of the box. 12ax7 triode as the input tube and the 12au7 as a cathode follower, first prototype of my tube ss hybrid design gain control and switchable clean dirty modes speakers are 3 philips old stock klon used to overdrive the pre, in the best audio It would have been helpful if you told us which amp we're talking about, as they certainly don't all respond to that equally. The better choice is a 12AT7 as a follower. Answer (1 of 4): Hi, thanks for the A2A. The return of the multivibrator to the normal state is de- 12AX7 is not the best for a cathode follower. The 12AU7 has the smallest, at just 20. Times have changed. The price we pay for this is gain, which is slightly less than unity. 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. This unit was simple but nice looking with its anodized "manley blue" sheet metal chassis. Advantages of Single-Sideband . The 12AX7 is a hi gain hi Z tube which is happy as a clam at 1mA. The cathode of the cathode follower would be within 5% of the same voltage as the plate of the first section (plus or minus the bias voltage between the grid and cathode of the cathode follower). 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. The RCA-IN34-A diode provides high harmonic content in the cathode -follower output. 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. 12AT7 VOX amplifier and calibrator oscillator. 4. share. - Change R7A and B to 1kOhm - Change R10A and B to 1.5 kOhm - Change R14A and B to 100 Ohm Lowering gain from 20 to 12dB: - Change R5A and B to 33 kOhm - Change R3A and B to 1 kOhm The 12AU7 is a low gain, lo Z tube which in turn makes it capable of pushing more current. He used 2 x 12AT7's for the cathode follower positions (T3A and T3B) to lower output impedance...he also changed a few resistor values. This tube offers low noise, low microphonics, and warm smooth tones at a great price. .. . The driver stage is constructed around a 12AT7 (phase inverter) and a ECC99 (cathode follower buffer stage). First of all, if you are using balanced inputs, you can forget about V1. Here are a number of highest rated 12ax7 Cathode Follower pictures upon internet. That'd certainly be close enough for my idea to work in principle. The cathode follower operates with 100% negative (voltage) feedback, which makes it exceptionally linear and minimises the output resistance. The heaters started to glow, and I was getting scratchy output when I probed for voltages. (which also covered circuits like the µ-follower and White cathode follower) or SEPP. Its submitted by government in the best field. Master the basics Design your amp Know it works Amp Design for the 21st Century. 12AT7, Amplification Factor = 60, Plate Resistance = 10,900 ohms. But the cathode follower also reduces the loss imposed by the tone circuit, so overall signal level is probably increased by using the cathode follower. Here is the SPICE-generated Fourier graph. But why not try a 12az7. The first stage uses self bias like the ELA M251 but it has no problem driving the Cathode follower output circuit that has and impedance 20 times lower than the 6072a with fixed bias. If the grid sees a signal large enough to cause it to swing between points 1 and 2, it will be distorted because the grid lines at point 1 are much closer together . The lower gain of the 12AT7 and 12AU7 also allows them to have a higher headroom, which can provide a warmer . 6146 Final amplifiers (2). V5 is your phase inverter, they are 12ax7 as well BUT selected with matched pairs, that's why eurotubes show them appart. Topic - Art Audio Vinyl One owners: which 12ax7 variant as a cathode follower? Because the AC cathode follower is normally used only as a transparent buffer for driving difficult loads, it makes sense to use a . A 6SN7 is an octal tube that requires a different tube socket. 12AU7 Sideband oscillator. I hope you enjoy the images. The triodes in a 12AX7/ECC83 make poor cathode followers, as the gm is very low. 6146 Final amplifiers (2). Without the ECC99 it would not be possible for the 12AT7 to produce sufficient current to properly run 4 KT90's. The red 'X' is the operating point and the green line is the loadline. Capable of driving a very low impedance. It's not used by the amp. These tubes should not affect sound, but they do o_O. So I hooked up the speaker and flipped the switch with no tubes. We identified it from trustworthy source. Perfect for the drive and recovery circuits for effects loops, etc. You want to be able to charge and discharge interconnect cable capacitance. We say yes this kind of 12ax7 Cathode Follower graphic could possibly be the most trending topic behind we portion it in google gain or facebook. to the grid of the 12AT7 cathode follower which prevents multivibrator loading and provides the final positive output. what is the difference between the 12ax7 12at7 and 12au7, 12au7 ecc82 cathode follower tube preamplifier schematic , cathode follower amp srpp power amplifiers , 12ax7 12au7 tube preamplifier power It was designed ONLY for a 12AU7. When a Tung-Sol 12AX7 dies in a cathode follower with 30 volts on the cathode, or in a phase inverter where the cathode might be 80 volts over ground, then it's the tube, not the circuit. First, the cathode follower was not designed for a 12AT7. Also a 1 meg resistor connected to the grid is in series with a . This unit later evolved into the Manley Purist Preamp which was later replaced by the Manley Shrimp Preamplifier.. The JJ 12AT7 (ECC81) is a lower gain variant of the 12AX7 and it can be used in place of a 12AX7 - NOTE that I mentioned "JJ 12AT7" specifically - because it is a short-plate tune. 12AT7's are a popular choice for cathode followers because of their higher transconductance and plate current. nearly the same amount, as do the grid, cathode, and plate of both V2 and V,. If we desired a lower impedance, we could replace the 6SN7 with a higher-mu triode, such as the 6SL7 or 12AT7, and add a negative feedback loop. In addition, the ACF does not invert the phase. This is true. ). The input stage consists of a 12AT7 ( ECC81) dual triode operated as a SRRP (aka totem pole or Mu follower) gain stage. #7. All in all the 12AT7 is a solid tool to design with. Introduction. A good choice for phase inverters, reverb drivers, and general preamp use. As for the right 12AT7 for the PV-3, the first thing is to learn what the 12AT7 does. 12AU7's make fantastic PI's and cathode followers. It might be 0.8 or so. You can indeed try to swap your PI position tube for something else on most amps, particularly if like in this case you go for a. Also you sometimes see it or a 12au7 driving a tone stack or using one of the triodes as a cathode follower. IMO, I think that you will get more out of the 12ax7 cathode follower pushing a tone stack unless you can make up for it with another . DC Coupled Cathode Follower . In the datasheet for every valve is a specification known as "Vkf". Oh yeah I'm having fun with it. The 68K resistor on the cathode is fine for a U7 and a bit lower than most cathode followers with an X7. 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. In the above figure, the 12AT7 has a 400V B+, a 26k ohm load resistor, and an 800 ohm cathode resistor. The JJ 12AT7 is a solid replacement for any 12AT7, ECC81, or 6 Thus, for example, when the level at the input is increased by 100 volts, the plate and cathode of VI both rise b,. Make sure that is the tube in the cathode follower socket. I then installed a vintage Siemens 12AT7 cathode follower in the phono stage and an early (shield logo) Mullard 12AT7 in the line stage follower position. the gain stages of the circuit are 3 (in my view) V1=12ay7 + V2=6N2P + V3=6ak5, the following tube V4=6N2P has "no" gain as it is a CF. The 2 tube preamp design with a cathode follower driving a tone stack is what I settled on driving a EL34 S.E. Mode2: Ef86-12ax7-12ax7+cathode follower-12ax7+cathode follower-EL84. It is a very simple change to make:-1- disconnect pins 6,7 & 8 from ground. The 12AT7 type has 10 times the anode current of a 12AX7 and so the voltage drop across the anode resistors is 10 times more resulting in the 12AT7 being starved of volts. Tweet. It has all the characteristic. Even considering adding a cathode follower after it. It depends if the reverb driver circuit uses a transformer or a cathode-follower configuration - if it's a cathode-follower then using a 12AT7 is probably not safe, and may be why a 12AU7 was chosen instead. Second, your schematic indicates a 12AT7. of the 12AT7) which then supplies the equivalent negative pulse. téma Audiofil ledna 2019 12AU7 ECC82 Cathode Follower Tube Preamplifier Schematic Audiofil Electronics Projects Schéma Guitar preamp circuit over drive using 12AU7 DIY 12AU7 Tube Preamplifier Project April 15th, 2019 - 12AU7 Tube Preamplifier Schematic by Tim William My version of the preamp has been slightly modified so that I could use . The output will be feeding a resistor network of a little less than 1K through a .001uF cap. I was surprised to hear the significant improvement wrought by each of these tube installations, especially in the follower positions, which are supposed to have less sonic effect. In other words, the ACF-2 is a unity-gain buffer for those who do not need any extra voltage gain, but do need more current delivery than a passive line stage would allow. 08-09-2021, 03:31 PM. The circuit is base on 12AX7/ECC83/CV4004 preamp stage and 12AT7/ECC81/CV4002 cathode follower in connection similar with SRPP but no gain, The souding very musicial which is as good as Marantz 7, But better high&low range response,Also better analysis and dynamic. It's in the heater chain with the other tubes (since MC uses 24v for heaters), so removing it will remove a part of the heater circuit. The carrier oscillator is provided by the triode of a 12AX7.
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