12au7 cathode follower schematic. 12au7 cathode follower schematic.
- 12au7 cathode follower schematic 14 Feb 2024. This value exceeds the tube rating for heater to cathode voltage and will result in tube failure. two stage12au7 tube preamp schematic 12ax7 / 12au7 tube preamplifier schematicLm3886 gainclone supply cathode follower power application 56w note diy 90v 12au7 calculating using bridge schematics size recommend study also. I have been told that substituting my. 002 = 72. The VA has plate load resistor of 120K and a cathode resistor of 1. The overall gain is about 8 times. Trio, LeeStereo, both great posts. When we cascade the input stage and White cathode follower we get a PSRR of -29dB, As I surveyed the supplied schematic, I queried the use of a 1. With 300V HT+, this difference is about 200V. These feed directly into single 12AU7 triodes running as cathode followers with 2N2222 current sinks set to 1mA. I finally decided to design my own cathode follower using the 12Au7 tubes with the following If the CF is cathode biased at 145V, then the voltage measured from the cathode to the plate would be 195V. Grid stoppers are important to keep oscillations from occurring, especially for the cathode follower. My phono preamp uses some in the cathode follower output stage and either type will do fine there. The CF stage has no plate resistor and has a 30K cathode resistor. Here is schematics: An externally hosted image should be here but it was not working when we last tested it. 12AX7 has poor drive capability, a 12AU7 or 12AT7 would be more appropriate, FWIW: in the 'audio' range, the AX7 may be the most used cathode follower in serious gear, going back to the K2-W opamp. Both of those exceed the design parameters of the 12AX7, which is 330v on the plate and 200V cathode to heater voltage, which also is affected by whether it's positive or negative. Or a triode strapped pentode, like Salas' 6V6 schematic Or a trioded EL84 Vincent77. The grid bias on the cathode follower is only -0. In the above schematic, the 6SN7 triode has a 600-volt window to operate within, allowing fairly large, say +/-250V, output swings. Some valve stages such as cathode followers require the heater supply to be elevated to avoid exceeding the valve's Vhk(max) rating. 8K. I used 12au7 tubes and a b voltage of about 150v. M. 12AU7's make fantastic PI's and cathode followers. Something like 6. ILoveHiFi Post subject: Re: Post subject: Re: 4S Tube Preamp with 12AU7 Cathode-Follower Output Stage. In the schematic 12AU7 (ECC82) Cathode Follower Tube Preamplifier Schematic This schematic below is a simple two stage line-level preamplifier using a single 12AU7 (ECC82) tube per channel. cvanc. (200 / 2 = 100V) for maximum headroom in the cathode follower. Many, How can I modify the cathode follower (currently with ecc82) To me this 12au7 seems polarized with little current, from the readings I have done on this forum. Prev. I used a 3V battery in the above schematic to bias triode T3, Yes, the SVT uses a cathode follower which is DC COUPLED to the output tubes. This is the Link to a side with my version. Optimized White cathode follower with Ra=Rp/mu another good suggestion maybe? Does it sound really good vs single ended ccsed cathode NEW Matt presents bias and operation data for the 6V6 tube in SE operation - 6V6 Single-Ended (SE) Ultra Linear (UL) Bias Optimization. Posted: 02 Jan 2020 3:25 pm . The cathode follower then effectively multiplies or bootstraps the value of the lower anode resistor R2, making it look like a constant-current source. I have some parts I'd like to turn into a preamp. I am glad at least the Aikido PS1 is adequate for a PSU. I visited The Valve Wizard a lot, and the schematics of cathode follower that I use in original post is from that website. I suspect a schematic would answer most of these questions. Member. If you’d like something with just a little more nerd sprinkled on top (and an extra 12AU7), try the following. By varying the trimpot the DC output of the opamp –and therefore the grid bias– can be altered to suit different valves, allowing the optimum working conditions to be found quite easily. Mike L. which then drives a bootstrapped 12AU7 cathode follower driver stage, which drives a UL connected 6550 output stage. c. Joined 2011. A PS-3 or PS-4 power supply would be perfect mate for the ACF. I have not tried 12AU7 in V3. k. I am wanting to use a cathode follower so that I can run both tube and ss power sections as I have read that using the CF drops the output impedance enough for solid state power to be happy. You'll see that a 12AU7 without cathode bypass gives about 20dBv of gain. 12au7 (ecc82) cathode follower tube preamplifier schematic. I looked at the mu-follower too. Is there any issue to use both outputs (hi-Z and lo-Z) at the of course, but I think an SVT sounds pretty good, and the power tubes are driven by 12AU7 cathode followers. Seeking advice. It can be thought of as being half-way between an ordinary gain stage and a cathode follower, and provided the anode and cathode loads are exactly equal (including any external loads) we are guaranteed to get equal-but-opposite signal voltages developed across them, i. Nevertheless I could not find yet a complete schematic for a IRF820 buffer. If you are using this in the preamp stage, the gain will be about ≈21v/v or 26. output all the way to ground, a cathode resistor is added so that the working cathode voltage will be about 3V, and the grid voltage just under this. Don't know the reasons why this tubet sounds good in mu follower and awful in a simple grounded cathode configuration (so don't ask me). You end up with lower gain from the tube, but otherwise things 'just work' more I have this old Ampex 1260, and found an old service manual, and it says “recommended load impedance of 250k ohms or greater. Aikido Cathode Follower The second stage in the Aikido Cascode is an Aikido cathode follower. However in my travels online for a solution, I noticed that on this site the 12AX7's and other similar valves were used in linestage designs postedand that the 12AU7 (ECC82) Cathode Follower Tube Preamplifier Schematic - as listed in this site - appears to show promise in being able to be used/modified into the cathode follower stage of the Cathode follower schematic circuit features click diagram description below specialCalculating cathode follower using 12au7 for 90v supply More cathode follower stuffBrains & brawn cathode follower. Joined 2015. Also, the coupling cap from the cathode of the cathode follower to the halfway point of the input tube's split plate resistance will need a quite large value of C for good bass extension. BTW, schematic was recommended by Bruce Rozentblitz. In a SRPP the cathode on the upper triode has a voltage potential of roughly 1/2 the applied B+. Out Phono Preamp schematic here. ” From reading whatever I could find, it seems a 12au7 cathode follower usually has a very low impedance, like below 600ohms. I've read lots of positive remarks from posters swapping 12BH7 for 12AU7/ECC82. 1; 2; 3; With 12au7 20*2400 (single cathode value) grid leak" is incorporated the way it is because the "fixed biased" by virtue of the d. DeathRex. Depends on how your heaters are set up, if the setup in schematic design is poor quality then DC heaters will reduce noise. The cathode follower therefore acts as a well-regulated voltage source to create a fixed DC grid bias for the LTP. For such individuals, the 12AX7 & 12AU7 combination will realize a gain of 200 (+46dB), but the 12AX7 cannot compete in a low-noise race with the previously listed tubes. Senior Member. two stageTube 12au7 preamplifier preamp schematic diy amp valve amplifier circuit headphone guitar circuits schematics diagram electronics tubed electronic tubes tim Cathode follower 12ax7 rocket speak12ax7 schematic tube preamp amp preamplifier bass circuit diy kit vacuum amplifier Not really liking mu-follower though. Typically that tube swap is not a problem. Thread starter woodturner-fran; Start date 2021-12-20 8:45 pm; Jump to Latest W. Merlinb. First off I will start with the schematic by Tim Williams from which my project is based on. Dipping into Merlin Blencowe's "Designing Tube Guitar and Bass Preamps" I found the part about rounded clipping from a cathode follower drawing grid current. The 12AU7 has great potential as a classic rock tone tool, but if you like higher gain levels, it's not the right tube, IMHO. What do you guys think of using LED to bias a 12AU7 cathode follower? How does LED bias compare to using the B+ with a potential divider on the grid? How does LED bias compare to cathode resistor bias Back to needing your schematic. However these tubes mainly date back to the days of mono so there is no reason that you cannot use a 12AT7 for the amplfier part of both channels and the 12AU7 for the cathode part of both channels. Hence, their popularity in the output circuits of many preamplifiers. 2. Two stage 12AU7 preamplifier with low impedance output stage. Because the output stage in the 260 is operated in UL, A 12au7 gain stage followed by a pair of 6dj8 tubes as white cathode follower output buffers. However, you do need to After all I had a cathode-follower in my mind originally. A few hundred Ohms between the output cathode and output jack helps to damp potentially resonant tanks that can form. Capable of driving a very low impedance. Making a bipolar, high-voltage power supply is not difficult, We use the 12AX7 triode as the input tube and Yes, Merlinb, I realized after posting that I forgot to include the 12BH7 stage in the cathode follower output stage in the schematic. During start up this value is actually 1/2 the full B+ (of about 275 V). It sets the operating point of the tube and helps in achieving the desired gain and linearity. and 6. I think this is correct. For example, since many tubes, such as the 6SN7 and 12AU7 the cathode resistor value is no longer a hair-trigger mess. It was designed ONLY for a 12AU7. Even at 150v i could not get the 12ax7 tubes to bias properly. The simple basic amplifier design that boutique builders favour uses 12AX7's in their preamps. of the 12AU7's cathode potential. Check Details. The overall If you need less gain, take a look at the RCA 12AU7 / ECC82 Cathode Follower Tube Preamp Schematic which has a gain of about 8. I already have 2 paris of 12Au7 which is an excellent tube for buffers as it will be unity gain stage cathode follower. Joined 2010. > 12au7 white cathode follower What are you driving? If only 10K and up, 12AU7 is not the ultimate choice but very good. e. At least there was one in the original EAR834P I had. This resistor is connected to the cathode of the vacuum tube and helps to provide the necessary biasing for the tube. I tried it with a ZVN0545 source follower, but the clipping was too sharp-edged. JojoD . EDIT: The wiper on the pot would connect to the grid, the top of the pot would connect to the node between C2 and R6. 96v RMS. Post Cancel. cjalbum 조회 수: 35383, This schematic below is a simple two stage line-level preamplifier using. A higher negative bias voltage would be advisable, even for a cathode follower. I've modeled 12AT7 and 12AU7 cathode followers into a 10k load, and they'll suffice. Joined 2005. Finally, the cathode follower actually has a small loss (≈ -1dBv). I noticed a mistake in all the schematics I saw. The Deluxe Reverb AB763 doesn't have a CF. 3V at 2. I decided on the cathode follower mostly because of the simplicity of the circuit. You’ll note that I have the B+ listed at 300v. I did this because both the 4S and the cathode follower work better up there. I am curious what consensus here is regarding the sonic merit of cathode followers. oh oh, Ive seen this schematic before, and he's driving the 6922 too hard: I suggested more tubes involved for example an input with a twin cascode or SRPP 12AU7 with a cathode follower 6DJ8 to lower the output impedance, total 5 tubes for a stereo preamp. This is not a particularly accurate answer, since the method of determining g m was crude, but this does not matter, since it is usual to operate an audio cathode follower Yeah, I could live with 2K output impedance if the split cathode resistance scenario offered significantly less gain, like 0. D. But for a cathode follower, R L from the anode to the HT is 0, so this equation is frequently approximated to 1/g m. ECC802S (12AU7 / ECC82) Tube SRPP Preamp Build Details. By the way, here are the values for the output transformer: Input impedance = 11. So, I'm working on step 1 of my plan outlined here to improve the sound of my Blackheart Killer Ant amplifier (2 x 12ax7 tubes, 1/4W, Class A) by replacing the 12ax7 "power" tube (V2) with a 12au7 for more clean headroom. Some direct coupled experimental discussion schematic I would say. So I built a "tubelab SSE" circuit a while back and fell in love with it. Good clarity, but too much volume loss. However, I'm having trouble understanding what to do about the heater-to-cathode voltage. Power supply will be 90V. Choose the plate resistor value for V1. If you Discover a detailed 12au7 preamp schematic and learn how to build your own preamplifier for audio systems. There are better theoretical tube choices for a cathode follower for a lower output impedance, like the ECC99 or ECC88. Reasons for its staggering popularity are not hard to find. (12AU7 / ECC82 Cathode Follower Tube Preamplifier Schematic). 5 amp - or is the voltage DIY Audio Schematics Tube Linestage Preamplifiers. Cathode-Follower OTL It seems as if every week, there's another schematic for me to review. Exactly why that would be I don't know. Give the value of resistors for current from 6mA? 😕 Here arranged thy schematic with ECC82 😉 🙂 Thanks and cheers! Am considering using a cathode follower output stage after the gain stage. Joined: 19 Oct 2018 9:30 pm The original 4S power supply diagram uses two 100R between the heaters and the It’s pretty tight where the tubes are, as it was built as a 4S Universal initially, and then the cathode follower was added, with not a lot of room available. I figured I could do without the power tubes and make a simple stereo vacuum tube design using 2 (or so) pre-amp tubes minimizing much of The schematic says the output impedance should be 220k Ohms. The overall voltage gain of the circuit is about 8. 2004-04-12 5:14 pm #6 2004-04-12 5:14 you will be able to figure out how to convert it to 12AU7, 6. You may want to have more headroom at the input. Small signal pentodes usually have a lowish plate voltage, so there is no problem with DC coupling to a CF stage. 4S Universal Preamplifier for 12A*7 Tubes - (Project) NEW ; 12AU7 / ECC82 / ECC802S Tube SRPP Preamp Schematic - (Project) 12AX7 Tube Hi-Fi Preamplifier Schematic - (Project) 12AU7 / ECC82 Cathode Follower Tube Preamplifier Schematic; 5687 (LED bias) Tube Hi-Fi Preamplifier Schematic - (Project) I am looking for a Grommes 260A schematic for the circuit that has 3 X 12AU7. You should get around 1. 4mA plate current). I intend to try something like that with a phono preamp that I have on the drawing board except I will be using 12AY7 for the bottom tube of the first stage. Given 100% local current NFB, the 'U7 is OK in the cathode follower role. Its design is based on one of my earliest microphone preamplifier designs hence the The drive problem is solved by changing the tube to a 6922. Thats why I was thinking some goofy NFB correction thing going on. vinylkid58. C. Unfortunately for all of you, it is in German but I think the schematic speeks for itself. The 12AX7 is a hi gain hi Z tube which is happy as a clam at 1mA. So I put a 12AU7 cathode follower at the end of the chain, and -1. But even when not explicitly needed, The ECC81 / 12AT7, ECC82 / 12AU7, and 12AY7, also have the same pinout. Maybe ideally right at the cathode pin, but really anywhere will do the job better than nothing. But, I checked one of my suppliers, and I can source In a SRPP the cathode on the upper triode has a voltage potential of roughly 1/2 the applied B+. The circuit steps down a high positive voltage to a lower output voltage while providing current amplification. Hoffman Amplifiers Tube Amp Forum, Kagliostro 12AU7 push pull schematic. Title: Cathode followerwith 12au7 Created Date: 8/28/2013 7:56:17 AM 12AU7 (ECC82) Cathode Follower Tube Preamplifier Schematic This schematic below is a simple two stage line-level preamplifier using a single 12AU7 (ECC82) tube per channel. But even when not Mar 22, 2024 - 12AU7 (ECC82) Cathode Follower Tube Preamplifier Schematic. Pretty much everything in the preamp is standard tube amplifier construction. Designing an AC Cathode Follower The ECC82/12AU7 is well suited to this job because it is cheap and plentiful, its low internal anode resistance allows it to deliver relatively large signal swings into heavy loads, and its moderate transconductance will guarentee fairly low output impedance which ensures wide bandwidth. Conceptual schematics takes some working usually irl. I think that That would be nice to use the 12AX7 for the amplfier and the 12AU7 for the cathode follower part. do you think that since the schematic is made for 12AU7 will work directly or needs to be moded to fit in the 12AY7 output impedance, polarity) you can either make a single gain stage (hence inverting polarity), add a cathode follower for lower output impedance or cascade two stages for higher gain and non-inverting output. In this case at half HT (Va = 100V) and an anode Something that might be worth trying is using a mu-follower with 12AX7 on the bottom and 12AU7 on the top and eliminating the cathode followers. Is this what you plan to drive with 12AU7 cathode follower ? After reading Merlin's post on the sound of DC coupled cathode followers when they're set up to steal current from the previous stage, I'd like to toy with them in my next amp, which uses a solid state tonestack. Not so much that they are alike, but frequently the settings work out the same. If you are driving 600 ohms to Pro levels, the 12AU7 just won't do well. In this schematic all resistors are 1/2w except the 10kω cathode follower load resistor which should be 1w. My signal path is: DC coupled cathode follower 12AU7 Edcor 600:600 transformer pins 2-3 of the XLR Pin 1 goes to ground via a lift switch This is pretty much straight out of the Thunderfunk book. I don't like this tube but I have some nice NOS 12AU7's so I built this preamp. In V4, it reduced the amp's volume level about 2 dial position markers. anyway, there's one with a black mask for $10 and one with a blue mask for $12, the schematics (attached) seem similar. Well, Let's leave the Darkvoice 336SE behind and use a 12AU7-based cathode-coupled amplifier input stage. 12AU7 I have 10s of yummy NOS treasures so I wanna use 12AU7 so to change colors. I've attached a load line example of a 12AU7 cathode follower design with a 50kΩ load resistor (RL), a NEW Matt presents bias and operation data for the 6V6 tube in SE operation - 6V6 Single-Ended (SE) Ultra Linear (UL) Bias Optimization. The little PV Classic 50/50 stereo amp uses 12AT7 CFs to drive the EL84 power tubes. Common-cathode (a. The 12au7 ecc82 is a twin triode vacuum tube it is very popular in the audio world because it is rather rugged and can be operated at lower voltages. This ensures the cathode follower acts as a CCS for a long as possible before cutting off or saturating. Two stage 12AU7 preamplifier with low impedance Cathode follower 1/2 of a 12AX7 or a 12AU7 can be used as a Cathode follower. However- take a 12AU7 under the same load: Vout-max = 300 * 600/(12000 + 600) = 14. Otherwise, I want to make and the cathode followe with your ECC82 (12AU7) to hear how it sounds. The cathode resistor for V2 will be the same value. Hi, Yes it ought to work, the gain will be more though. 12AU7 / ECC82 Cathode Follower Tube Preamp Schematic file. Skip to main content. 12AU7 (ECC82) Cathode Follower Tube Preamplifier Schematic from diyaudioprojects. It would allow you two channels with just two tubes. 5k ohm Output impedance = 133 ohm Cathode followers work best when they are used to produce a low source resistance, rather than to drive a low load resistance. The ECC81 / 12AT7, ECC82 / 12AU7, and 12AY7, also have the same pinout. 12AU7 might not be the best linear triode but it is not as bad as many people tell. a. I have been told that substituting my present Philips Miniwatt for a mil spec tube like the 5814A, others things remaining unchanged, I will get a more powerful and defined bass. Welcome To the Hoffman Amplifiers Forum December 26, 2024, 05:31:20 pm: Welcome, Guest. A chart of these gains can be found on the 4S project page here. I’ll post a power supply schematic shortly. You cant trust dc output. 2021-12-20 8:45 Va=233V (50V or so lower than the Any tube will do in that position, a cathode follower is a topology that doesnt provide "colour" to the sound, you could even put a wimpy 12ax7 (requires changing cathode resistor like any other different tube) because the driver requeriments of a 6y6 in that configuration are not very high, if you have 6n1p, 6n6p, 12au7, 6sn7, ecc88 variants they will all be equally The cathode resistor is also an essential part of the 12AU7 preamp schematic. I could not find any ready made schematic of any tube buffer available which i could directly implement using the 12Au7 tubes. Is this okay? Attached schematics used for simulation and frequency plot Thank you for helping. If we are to use tubes with Vhk max of 100V, we are really close to the limit. If you need less gain, take a look at the RCA 12AU7 / ECC82 Cathode Follower Tube Preamp Schematic which has a gain of about 8. 12au7 / ecc82 cathode follower tube preamplifier schematic Cathode follower output load tubecad 2005 june. The schematic shows 300 Volts B+. Been searching the net for a foreplay schematic but can't find one except for a modified foreplay with 6N1P tubes. -User I'm a Cathode Follower! Can we have everything louder than everything else? shooter. Posted: 04 Dec 2018 2:19 pm . Cathode followers themselves function from local degenerative feedback. As there is quite potential difference between the upper and lower cathode. have used the design as seen in the schematic with low impedance cans for quite a while and it performs pretty well. coupling from the prior stage cathode follower. There is no cathode resistor for biasing, whose "ground It was exactly what was on the JCM800 50/100 schematic - but apparently not the correct way to do it. Better yet would be a 5687 or 6N6P, since those have lower plate resistance, so can drive 10k with relative ease. For example, the 5E8A Tweed Twin has a CF for valve 3. Better go with a ECC82 / 12AU7 / 5814A. perfectly balanced outputs. In other words, each channel Maybe use the 12AU7 (or the 6189) as a cathode follower: less gain and low output impedance? Reactions: myfirstamplifier. First, the cathode follower was not designed for a 12AT7. But I'm trying to figure out if using a triode other than that of the same tube (like a typical CF in guitar amps) will require special consideration to get similar performance. Merlin's article on DC coupled cathode followers refers to the way a cathode follower is coupled at it's input, not output. Remember, the tube references everything to its own cathode. Top . If one is a cathode follower, the other half has to be a voltage amp. I use 100K ALPS log pot for volume control. At least at the low levels I'm using it. 12AX7. Looking at schematics for the OG rectifier, the V3B cathode follower is putting 415V on the plate and 216V on the cathode. Joined 2009. Click to Note that V1's plate voltage biases the cathode follower! Tim . yes, you can also use bigger current in mosfet, from 2mA in the foreplay to about 10 in the IRF820 if you wish, but at that current you will need a small heatsink on the mosfet However in my travels online for a solution, I noticed that on this site the 12AX7's and other similar valves were used in linestage designs postedand that the 12AU7 (ECC82) Cathode Follower Tube Preamplifier Schematic - as listed in this site - appears to show promise in being able to be used/modified into the cathode follower stage of the JP200 preamp design. Because the cathode follower itself has a low-ish impedance of about 500 ohms, the resistor right below the cathode needs to be no larger than maybe 2. As such, the type makes a poor voltage amplifier. Make sure that is the tube in the cathode follower socket. Jim Marshall crafted guitar amplifier masterpieces without the assistance of computers, software or the Internet In 1963 "graphical methods" meant drawing Bode plots with a pencil and ruler Times have changed. 4dB with a bypassed To make the 12AU7 CCDA with the positive feedback to V1 cathode and NFB from output to V1 grid, you have to arrange for V1 and V2 to draw the same plate current (Ip). The 2 tube preamp The 12AU7 contains non-linear triodes. . DC coupling the cathode follower would only require 33K cathode resistor for about the same anode current, possibly slightly higher. Explore different circuit designs, component choices, and wiring diagrams for optimal sound quality. Cathode grid valve follower tube bias loop effects auto ac triode negative come than output You look at the schematic to see if it has a cathode follower. Mar 22, 2024 - 12AU7 (ECC82) Cathode Follower Tube Preamplifier Schematic. 1. Sep 18, 2010 #20 You’ll note that I have the B+ listed at 300v. A line stage with a 12AU7 configured as common cathode + DC coupled cathode follower can easily give THD <1% for 18-20V output. I would like to use 12AU7's as I have several of them. I cobbed this schematic together from this and this. However in my travels online for a solution, I noticed that on this site the 12AX7's and other similar valves were used in linestage designs postedand that the 12AU7 (ECC82) Cathode Follower Tube Preamplifier Schematic - as listed in this site - appears to show promise in being able to be used/modified into the cathode follower stage of the The cathode follower doesn't have any gain, but the first stage common-cathode 12AX7 certainly has gain. I'm still working out the particulars of the power supply. Level 3; Posts: 1426; Re: EF 86 Microphone preamp circuit « Reply #3 on: December 23, 2023, 12:05:01 am 12AU7-Cathode-Follower This circuit is under:, circuits, 12AU7 (ECC82) Cathode Follower Tube Preamplifier Schematic l24634 12AU7 (ECC82) Cathode Follower Tube Preamplifier Schematic. No question about this. Only so many ways to get that done. Schematic. The cathode follower is likely working with some grid current due to contact potential. 12AU7 Tube Preamplifier Schematic by Tim William High gm valves are well suited to cathode follower part of the circuit (such as an ECC82 / 12AU7). Second, your schematic indicates a 12AT7. 6 or something. Joined 2003. Cathode follower with tube 12au7(ECC82) Schematic. Kind regards, beppe . 5 Volts on the plate after the 100K plate load resistor. So Ra3 = 145 / 0. I've attached the load lines plus the roughly intended bias points. These are all 12AX7’s too by the looks of it as the 2x 12AU7’s are cathode followers. but with 12AU7, this is not a problem. It's just a little too powerful for the room it's in. Joined 2006. 4S Universal Preamplifier for 12A*7 Tubes - (Project) NEW ; 12AU7 / ECC82 / ECC802S Tube SRPP Preamp Schematic - (Project) 12AX7 Tube Hi-Fi Preamplifier Schematic - (Project) 12AU7 / ECC82 Cathode Follower Tube Preamplifier Schematic; 5687 (LED bias) Tube Hi-Fi Preamplifier Schematic - (Project) The 4S preamp has a gain which is dependent on the tube used and dependent on whether the cathode is bypassed or not. With respect to my voltages while using a 12AU7 in both positions, my B+ before the 100K plate load resistor is 266 Volts, and there is 68. 28v, which equates to about 4. 12AU7 Preamp Schematic. Aikido CF PCBs and kits are available now at the GlassWare-Yahoo store. Actually, in keeping with the first law of engineering (“Nothing of value comes without a cost”), this extra resistor’s added benefits must be paid for with a higher output impedance and slightly less voltage and current swing. The grid would be biased at -1V relative to the cathode, so looking at the plate curves, there would be about 2mA flowing through the tube and Ra3. Neither is it an aikido follower. In your example however i'm not following your derivation of the quiescent plate voltage on the tube. If you need less gain, take a look Author Topic: 12AX7's like the tung sol RI that can't handle cathode follower voltage (Read 8186 times) 0 Members and 1 Guest are viewing this topic. 12au7 Cathode Follower Schematic. DC coupled cathode follower - Design Q's 02-05-2011 and the tubes are 12au7's. I don't really know how complicated a 12au7 per channel preamp could be. 6 to 1. The BEST combo I have used yet is: V1: ECC823 V2: ECC83s V3: ECC83MG V4: JJ5751 Of course it is a follower and will follow the input voltage, but for a very short period it will draw grid current if the signal swings too fast and too high. One pair EH, one pair GE NOS. Does anyone have anecdotal evidence to support his praise for their effect on the sound in an amp? I'm considering using them in two places in the amp - Hi, I mapped the schematic of this preamp with my resistor values. 8uF to 10uF would be necessary with a 6SN7. A Cathode follower is often connected directly to the output of a high impedance Anode load pre-amp. Schematic attached. In SPICE simulations, this circuit as novel circuits must be created, SPICE simulations must be run, schematics must be drawn, and thousands of words must be In the next days with the help of a friend I will try to draw out the buffer schematic in order to evaluate the possibility of using a ECC99. Thats why I started with 12AU7, but then found ECC88 that I think is able to deliver output impedance Hi everyone, Need help calculating resistors for cathode follower. HP8903B. Master the basics Design your amp Know it works Amp Design for the 21st Century. I just made myself a couple of load lines for the cathode follower part of the schematic. In the world of tubes you can often swap the 12AU7s with 12AT7s and the reverse. Join Date: Aug 2006 06 May 2007. Frank is a regular here, I hope he spots the thread and will enlighten us. 2012-05-04 11:00 pm Aikido Cathode Follower [ACF] 6H30, 12AU7, 12AT7, 12BH7, 5963, 5965, and ECC99. You will need the Vp (plate voltage) of V1 to be 1/2 of B+ voltage. EF86 triode + 6CG7 cath follower preamp. The plate impedance of a The 73V output sets the DC voltage at the grids of the triodes forming the long-tailed-pair phase inverter. They make a sweet clean gain stage when looking for only a gain of 10. 5 dB with a unbypassed cathode and ≈33v/v or 30. 5 amp - or is the voltage 12ax7 Cathode Follower Schematic. Attached schematics used for simulation and frequency plot Thank you for helping. The Cathode follows the signal on the Post subject: Re: 4S Tube Preamp with 12AU7 Cathode-Follower Output Stage. Over the last few weeks I’ve been delving into the confusing world of direct coupled post phase inverter cathode follower drivers for push pull The voltages are straight from the Ampeg schematic, and Ken, given that tube could sink more current than a 12ax7 or a 12au7. It appears capable of ~12VRMS or 30Vpp out before it starts to clip which is WAY more than enough to drive headphones, even high-impedance cans. Schematic of the amplifier is here. A global feedback loop will be a connection from the output of the circuit all the way back to the first stage, which is not a type of feedback we use in our products (except the Tode guitar amp we offered some years back). This will get rid of 1 coupling cap and 2 resistors. This XL version uses a White Cathode Follower buffer for about half the output impedance of the vanilla version. The 12AU7 is a low gain, lo Z tube which in turn makes it capable of pushing more current. I will try to calculate/measure the present bias current. Take a look at the attached schematic and let me know what you think. Level 3 Schematics library: Design a custom Eyelet or Turret Board: DIY Layout Creator File analyzer program: DIY Layout Creator File library: Transformer Wiring Diagrams: 12AU7 (ECC82) Cathode Follower Tube Preamplifier Schematic. Is there anything I'm missing here in regards to "designing" (ripping off Schematic attached! Attached Files Comment. Dear Sirs, I am using a line stage consisting in a pot followed by a 12AU7(ECC82) in a cathode-follower configuration. 2022-01-13 4:55 pm #4 I employed a 12au7 triode as the reverb driver and thought to use the other half as the AC30 preamp type cathode follower. The bottom of the pot would go to ground. com. But, it's a great introduction to some of the issues involved in DC coupling which aren't a concern in an AC coupled stage. 3. This is a high gain preamplifier that is suitable for use where a lot of gain is required - to drive a power amplifier that needs plenty of gain or perhaps for use with instruments, like a guitar or microphone. In the 12AT7's are a popular choice for cathode followers because of their higher transconductance and plate current. 2V grid bias (4. According to the Cathode Follower calculator, with a 220kΩ cathode resistor the output impedance is only 617Ω. So with 215-225 V on the anode the cathode is over 100 V. I've DC coupled a 5879 to a 12AU7 before (in a circuit using Merlin's morph control but with the triode coupling mode buffered from the CF) - schematic attached (with voltages. If you post up specific models of amps, I can search for the schematic and tell you. woodturner-fran. 7. Logged Toxophilite. The output This schematic shows a cathode follower circuit using a 12au7 vacuum tube with associated resistors and capacitors. 12BH7 I have 2 types. The actual gain will never be 20. It sounds quite good. 5K. A load line or schematic would help. Level 5; Does anyone have a schematic for adding a balanced line output? I just want to double check what I have done on a bass amp I built for a friend. However in my travels online for a solution, I noticed that on this site the 12AX7's and other similar valves were used in linestage designs postedand that the 12AU7 (ECC82) Cathode Follower Tube Preamplifier Schematic - as listed in this site - appears to show promise in being able to be used/modified into the cathode follower stage of the What is the purpose of a cathode bypass capacitor in a White Cathode Follower buffer? By the way. In 12AU7 cathode followers, its more common to see 5mA Thank you very much for the helpful advice. 8 Meg cathode resistor, DIY Audio Schematics Tube Linestage Preamplifiers. The plate of the 12AU7 used for a cathode follower is at 266 Volts as well. It requires a few extra resistors and caps and the heater reference voltage is tweaked just slightly so I can sleep better. Separately, it's always a good idea to include cathode stops for follower outputs driving the cold cruel world outside the box. In the schematic below, we see both a cathode follower and a White cathode follower with extra cathode resistors. separate heater wires to the switch and to the 12AU7 cathode follower ? Is the Allied 6K49VG power transformer suitable for the 4S - 460VCT at 50ma. H. The idea is to take advantage of what I hear is a very linear EF86 triode mode inverted output is taken from the cathode. 12au7 cathode follower schematic Cathode follower again ;)no rocket science! Lm3886 gainclone supply cathode follower power application 56w note diy 90v 12au7 calculating using bridge schematics size recommend study also V2A - Cathode Follower V2B - AF Amp V3A - AF Amp V4 - Cathode Follower So should I focus my best tubes on the Pre Amp and Amp stages? I’m a bit new to all of this. The preamp is basically a voltage amplifier (VA) DC coupled to a cathode follower (CF) stage. may even work for that with bigger output capacitors. 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). Really reminds me of the morgan-jones headphone amplifier. Schematic I was messing with. The input volume control doesn't have to be The FX Buffer Cathode Follower is used to prevent FX pedals from loading down the high impedance guitar signal an inverted signal at its plate but also acts like a cathode follower by outputting a non-inverted signal at its cathode. Without knowing you have taken a conceptual discussion schematic from glassware and tries to implement it. There should be an additional RC filter between the second stage and the cathode follower. 2K to keep the overall output impedance less than 2K. The 5F6A Tweed Bassman has a CF for valve 2. It is surely a better choice than SRPP from this point of view. Two-amplifier cascade part ii Follower cathode 12ax7 recommend cathod folks against why using schematic output plate follows looks Ef86 amplifier ac4 inspired 12ax7 some. This post has a file attachment. From the anode characteristics, g m ≈5 mA/V; this gives an output resistance of ≈200 Ω. Lets leave aside the silly topic about the source. Please login or register. Here is the entire schematic. Cathode follower, opamp chip, etc would be a fix. although I bet that 6SN7s or 12AU7s would work just fine. 12au7 ecc82 cathode follower tube preamp schematic. You don't see 12AU7's in guitar amp FX loops very often because they tend to use more current than the entire rest of the preamp by the time you get a decent signal swing out of them. Nor a white follower. 2018-02-15 6:41 am #5 2018-02-15 6:41 am #5 Picture 12au7 cathode follower schematic. Title: Cathode followerwith 12au7 Created Date: 8/28/2013 7:56:17 AM I know they exist, as I get email from its members all the time, asking if an Aikido or a White cathode follower can be transformed into an SRPP. This schematic below is a simple two stage line-level preamplifier using a single 12AU7 (ECC82) tube per channel. I don’t think it is power supply related, as the original 4S was pretty much dead silent except for a bit of tube rush at full volume. 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 Cathode Follower Calculator. 2023-01-06 5:43 pm #4 Here's a simple schematic with basic 12au7 cathode follower CCS check. 5V. No. You aren't looking for gain, you want a current source so they are the obvious choice. But in reality, you could go anywhere from 250v to about 330v on the power supply without any issues. Another use for a second triode is as a cathode follower, The following unity-gain anode follower uses a 12DW7/ECC832 tube, which holds a 12AX7 triode and 12AU7 triode. 2013-02-05 1:01 pm This is done by splitting the previous stage's anode resistor into two equal parts and connecting a capacitor from the cathode follower's cathode, to the junction of the two resistors [see right]. The White cathode follower by itself delivers a PSRR of -11dB (29% of the ripple leaks out), but the ripple is inverted relative to what appears at the B+ voltage. 8VDC on the cathode. fmq ngzpre plkuir zhdmap vyijg bkbvf awnina zszxi rezw sunh