Ef86 voltage

See also Soviet Tube suffixes. I have the parts from two philips el3541 tape recorders and would like to make these into two mono block amps Jul 19, 2018 · If the plate is significantly far from 100V the phase splitter will have a non-favorable working point. Use an even larger resistor to reduce the signal even more, or a smaller resistor to reduce the signal not so much. It's part of the feedback around the E88CC, the 1M6 resistor being the other part of the loop. I was told it is actually an EF86 with a different control grid to give it remote cut-off characteristics. Diversamente non ricordo schemi di amplificatori in vendita con questo tipo di valvola per il pre. Just finished the chassis for this at 11pm-ish tonight. Jan 24, 2006 · Not quite. The triodestrapped EF86 sounds great as lineamp. Since the EF86 is direct coupled to the phase inverter, you do want the EF86 plate voltage the same as in the original circuit where it was pentode wired. Mar 20, 2005 · The EF86 is the first stage of a Mullard 5-20. 1mA at 400v: Resistance = Volts / Current = (400v - 100v) / (2. That rules out 12AX7. Buffer the pentodes with ZVN0545A source followers DC coupled to the plates and your matched complementary FET pairs will do fine. I've found turning the Amplitude control to max brings the screen to up to ~70v, pulls the plate down to ~70v, and gives the most grit & gain. 6AU6 is a 7 pin pentode. A solution to this sort of problem is having a low noise, high transconductance, JFET source follower ideally load the cartridge and have the FET drive a step up microphone transformer. The voltages and currents are very much lower than normally. I now have +71vdc to cathode on 6 and -55 or so to the one on 3. 6267. Even compared with the classic EF86s from Telefunken and Mullard, the CV4085 is considered the best of all the EF86s equivalents. Page 7 of this EF86 data sheet shows a 2. When you switch on the amp you should see the pilot light come on indicating that the transformer is energized and the 6. #4. The EF86 valve is a low noise pentode designed by Mullard L. This is where screen voltage plays a key role. Jul 15, 2013 · It sends a voltage to the cathode of the EF86 preamp tube in pulses, while an array of capacitors and resistors along with the speed control determine the rate. It worked but not quite as well as the tube it replaced. Grid2 voltage 140V. 6Ф4П (6F4P) 6DQ8, 6DX8, ECL84. You don't often see small-signal pentodes in guitar amps, where the ECC83/12AX7 is king. However , on the ef86 side i've got low screen (74v) and plate (68v) voltages. Pin 4 must be positive with respect to pin 5. Think of it as sending a very low-sound signal to the EF86's cathode—maybe 2–10 Hz (cycles per second). All my voltages are ok but pin 6 of the ef86 is showing 6. Oct 29, 2016 · The original Mullard 5-20 uses an EF86 as the voltage amplifier and that meshes with your thinking. If you want an affordable alternative to Philips or Amperex, the Japanese Matsushita/GE EF86/6267 is the real deal with that delicate mesh shield. The tube with the screen mesh shield is the classic Mullard tube that was always supplied with the Eico kits, and always works great. 2) each channel on it's own. It is typically used as a preamp in audio equipment and instrument amplifiers. Grid Voltage Svetlana EF86 Typical Plate Charicteristics-1. I have built a VOX Ac15 schematic circuit and the clean channel has a very high gain and a lot of background noise amplified by this gain. I have a question regarding to the triode connection of an EF86. Care in the design of the valve to ensure that the electrode structure and its mounting are as rigid as possible can reduce the microphony of the EF86 to an insignificant level. Web References. 6,484. However the reverse is what has happened with the screen voltage being about 10-12 volts higher than the The EF86 vacuum tube is a high gain pentode designed to amplify low-level audio signals. I'd like to modify it to fit a single 6V6 power tube (I don't need 15W). Is it possible to reduce this? Is it normal for it to have a plate voltage of 120 Volts and an anode voltage of 95 Volts? Thank you Here are the transfer characteristics for an EF86 pentode, showing plate current versus grid voltage for several different screen voltages: Maximum plate voltage is at cutoff, where the plate current is zero. When the cathode voltage approaches the desired voltage, it would settle with a time constant of 500 uF/(gm + gm_screen), which is in the hundreds of milliseconds range. Yes. It's sounding good, I'm just wondering if I need to tweak any values to really tune the tube in or if I'm good as it is. You do need a low plate resistance. I remember now that I had similar trouble when using it as V1 in another pentode design. An EF86 was famously used as the input stage for the early Vox AC30s, but it acheived such high gain (about 200) and was used in such a sensitive position that microphonincs was a major problem. . 45Vrms, Av = 76Vrms that exceeds the max output of 44Vrms given by Philips. 5-3. Come to think of it, my AC10 probably has the same AC15 circuit on the EF86, and it sounds very chimey at lower volumes. 3V using a LT1085 voltage regulator. Basic price is $3150—the review sample featured 5Y3 rectification, Audio Note copper-foil-in-oil caps, M6 EI grain-oriented–core power transformers, and a choke-filtered Aug 18, 2012 · EF86 works as a voltage gain stage. However, the heater is isolated from the main circuit so that, for example, pin 5 may Dec 9, 2007 · The loop through the 22K from the EL84 cathode, smoothed into DC by the big bypass caps on it, holds the voltage on the EF86 screen at a certain level. The specification for a NOS CV4085 (EF86) under conditions of an HT voltage of 250V and an anode load of 100 kΩ is for an equivalent input noise voltage of 2μV (RMS) in the frequency range 25 to 10kHz. Steer clear of the 12AX7/ECC83 Mullard used as the LTP. Well, I connected a 1M resistor in parallel with the . #2. C1 mustard cap, C2 Elna silmic II, C3 Philips "orange" MKP, C4 Wima Apr 8, 2005 · The 220k load resistor on the AC15 circuit should result in a higher gain, and perhaps a glassiness that can give that Voxy top-boost sound that some folks like (the top-boost being Vox's replacement for EF86 in early AC30s). 5A) Optional diode bridges for rectifier. Aug 9, 2009 · For the voltage divider off of B+, which is about 250V, I used a 330k and 100k and connected my heater center tap to the junction through another 100k. Many specimens simply couldn't handle the Jul 3, 2019 · Hello there!, I love the Sluckey's 1960 Vox AC-15. Suggestions ef86 riaa. the b+ is good, all the resistors are good. Jul 15, 2013 · That oscillating voltage is connected to the cathode of the EF86 tube, which affects the bias. 0-1. Nov 22, 2018 · A particular EF86 that intrinsically draws more current, causes the EL84 grid voltage to go lower, causing the EL84 current to go down, causing the EF86 screen voltage to go down, causing the EF86 to draw less current. Above left: The EF86 characteristics at a fixed screen voltage of 100V. B+ was 315 Vdc (different power supply than recommended) and the output transformer had ~ 420 ohm primary DC resistance. This deck has EF86 Jan 23, 2011 · EF86 pre & parallel SE build Pics. Transformer Beyerdynamic BV310 1:10 (used with reversed sections). I had intended that the screen voltage be about 10 volts lower than the plate voltage. The new values shown on your diagram are the pretty standard values used and would work fine at a voltage of around 280-300V. 3v. loop to reduce the gain and distortion of the E88CC. Producer 88 – Figure-2. See also: American/European Tube Equivalents. I put together a modified 5E3 Tweed Deluxe into an old silverface champ. Taming the EF86. This will definitely get you away from weeding through dozens of EF86s to find one that will work. Its intended use is as an audio frequency voltage amplifier, particularly in the early stages of hight-gain audio amplifiers, microphone pre-amplifiers and magnetic tape One rectifier tube 5Z2/5Z3/5U4/6X4 and two pentodes EL84/6P14 and EF86/6J8. Hi, I´m about to rebuild an old PC86/6AV5GA SE amp to use more commonly available tubes like EF86 and 6L6GB/C/whatever. The filament supply is regulated at 6. Cathode-heater voltage, ±100V. Minimum plate voltage is at a grid voltage of zero. Close or identical. Warning: Substitutes are given as a guide only - please refer to original manufacturers data sheets to ensure that a substitute is safe and appropriate for your application. Jul 19, 2018 · The distortion, best measured across three EF86 was 0. « Reply #12 on: August 12, 2022, 01:49:50 pm ». Here is a plot of plate current versus grid voltage for an EF86 pentode. EF86 (Philips) @ Franks Electron Tubes. i swapped out ef86 tubes and the same. You want less gain, more gm, and lower plate resistance in that role. 0-4. 9k ohms Aug 26, 2020 · 6BM8, ECL82. As was stated earlier, the prototype circuit provided 6. Optional connector for choke 10H 150mA. #17. Watch heater power and case heat on the larger tuner twin-triodes. It was based on a Matchless DC-30. Capsule 35mm SE Electronics K67 Tube EF86 Lorenz NOS (really good 86 - sounds better than TFK). While pentodes like the EF86 are sometimes seen in guitar amplifier preamps, triodes like the 12AX7 are the overwhelming favorite for voltage amplification duties. Hoffman Amplifiers Tube Amp Forum, Low B+ voltage on EF86 preamp section. Merlin proposes to just ground the plate to make a triode strapped Above left: The EF86 characteristics at a fixed screen voltage of 100V. I know the usual way to connect the screen grid to plate. Svetlana EF86 is a glass envelope miniature pentode intended for high-quality audio preamplifier service. 5μV (RMS) under the same conditions. Merge Mullard's 5-20 with EICO's HF89: EF86 voltage amplifier, 6CG7/6SN7/7N7 LTP, and "fixed" bias O/P tubes. 27v. 0001A Jun 2, 2019 · (The lower gain designed in by a Mr. The input pentode circuitry for the VOX AC15 and other similar guitar amps was lifted straight from the back of a tube catalog. So the voltage gain of a pentode preamp is roughly these two extremes divided by the For the EF86 under normal conditions, I. If you were to run it with a much lower voltage you would undoubtedly have to make adjustments to several values and I have no idea how that would affect the tone, I would stick to the higher end for B+, sounds great there!! Sep 6, 2014 · Single-Ended (SE) EL34 Tube Amplifier Schematic with EF86 input stage. There isn't any triode quite like the EF86's triode mode. 5-2. « on: June 16, 2023, 11:39:23 PM ». and introduced in 1953 as a successor of the octal EL37A. But what I know for sure from an article in the German magazine FUNKSCHAU #4, 1957, is the PCC88 was introduced that year to replace the SQ tube E88CC which had appeared in TV frontends the year before. 05% (give or take on the last digit of the Keithley 2015 THD DMM). 87% with max at 1. If not, start at the AC supply fuse and see if there’s power coming in. com Datasheet (data sheet) search for integrated circuits (ic), semiconductors and other electronic components such as resistors, capacitors, transistors and diodes. 0-2. The TAD EF86 / 6267 meets all of the standards of the Tube Amp Doctor Premium Selection process. Jan 17, 2012 · Hi Edwind, As DF96 says the circuit is useless. (The gold pin variety) Here is a schematic pilfered from the Mcintosh MC2200 preamp, giving a tidy and simple phono pre-amp with 12AX7 and 12AT7 tubes. PCC88 can be regarded as successor of the E88CC, aimed Aug 25, 2015 · The Winged C EF86 has a taller plate with mesh shield that is similar to what you find in vintage Amperex or Philips tubes. CV4085 (Special EF86) LOW-NOISE AUDIO PENTODE. :confused: Wondering which will give the highest yield for a valve front end. Something like this CineMag transformer seems right for this situation. 1uf cap on the EF86 grid (forming a divider with the 1M resistor from the filter cap to the grid itself) and this took the voltage from about 120v down to 77v or so on the grid, and RAISED A tightly twisted pair may then be used to couple the rectified voltage across C 1 to the heater pins of the EF86. I just completed an amp design that involves 2 12AX7 stages in front of an EF86 pentode stage in the pre-amp. Jul 15, 2001 · Jul 15, 2001. Aug 12, 2017 · I've restored 1958 Telefunken 85 reel to reel, all working good but I cant' record at normal output levels from CD or sound card because it overloads. The EF86 in the voltage-amplifying stage is used under conditions approaching those of starvation operation, 20 V anode and 0,21 mA. They were built on the same equipment as the Philips. Sep 14, 2022 · My question is about the excessive gain of the EF86. 0-3. Power requirements: two 360/400V AC(100mA), one 12. I modified the cab to fit a 10" Celestion Vintage 10 speaker. 7ma or so of plate current (which would be good). But the circuit isn't real fussy. The first stage for Channel 2 of the Matchless DC-30 guitar amplifier contains an EF86 pentode that drives the effects send or the phase inverter via a switchable coupling capacitor CG and a 1MΩ volume control. 3) EF86 in series with other channel. EF86 (La Radiotechnique) @ Franks Electron Tubes. OK, a very easy thing to do would be replace the green wire between the Brilliance switch and the NOR Vol with a 470K resistor. 6Ф5П (6F5P) 6GV8, ECL85. 2023-05-25 9:55 am. 8 specified. With the given input sensitivity of 0. Aug 12, 2022 · Re: too much gain on Ef86 Vox Ac15. I have to drop the input volume to 50% for clean recording, than I can tweak the machine's recording level to set the level. Now I'm ready for a possible new project. The heaters should be elevated in any event, as this degrades the heater insulation and eventually cause an early failure. Let's also assume the preamp drives a 1M gain control, which is a relatively light load, even for a pentode. 1mA - 2mA) = 300v / 0. Mar 15, 2017 · A common mod for Vox amps with an EF86 as preamp tube is to alter the value of the screen grid resistor Rg2 Substitutes. All the other EF's were intended primarily for RF use. Voltage boost by a factor of 100 is just beyond the reach of a 12AX7 triode, but well within the capabilities of an EF86 in pentode mode, as we will see. ) For new builds I find more justification in keeping the EF86 stage as pentode as originally, with rather a lower µ tube as driver/phase inverter, say ECC82 EF86 Voltage Amplifier Pentode Components datasheet pdf data sheet FREE from Datasheet4U. Adding an IDH tube rectifier to get delayed B+ is unfortunately Jan 10, 2007 · The first capacitor is mandatory to properly bias the EF86. The raw B+ is around 400V during startup and I want to replace the messy Mosfet capacitance multiplier in the PSU with a simple choke. Correct, that is negative feedback. All's fine on the tmb channel and power section, all the voltages are correct to within 10%. Because the screen volts went up, this means the wiper of the Amplitude control went to ground leaving a voltage divider of Power Supply Sep 9, 2006 · Usereste una EF86 come pre? In molti schemi "amatoriali" si trova una EF86 come stadio preamplificatore al posto delle solite 12AX7, ecc. Because of its design, the EF86 is much more sensitive than other common preamp tubes like the 12AX7, and achieves more gain. by dartanion » Wed Feb 07, 2007 10:22 pm. Some are almost useless for audio. Note that the knee is well defined, and the input sensitiviy is lowest: If centre biased it would take roughly a 4Vp-p input signal to cause clipping. artosalo said: Triode connected EF86 has gain comparable to any medium mu triode and thus can be used easily with some NFB, which improves the linearity as well. (vox ac15 heritage) Apr 26, 2022 · A different screen voltage changes the gain of the EF86. 5-5. Microphony. Resistance in grid1 circuit, 3 MOhm. 5v vs the 0. Jan 31, 2023 · 2023-01-31 3:05 am. The phenomenon is common enough among high R P / low gm types; look at the 12AX7. This is similar to the Mullard 5-20 design and that can be quite fussy about EF86 anode voltage. The results? An amp with a very warm character full of bottom end. 9v cathode voltage through the 2200 ohm cathode resistor on the EF86, about 2. It breaks a little when cranked, but in low to mid range, dont like it. Need to visit this site later when at home again. Apr 21, 2004 · Ei apparently did make an EF86, and it definitely did make LOTS of PF86. The dedicated premium tube by Electro Harmonix®️ Aug 11, 2012 · [PROJECT FINISHED] Last design this year ;) Cardioid only. 2V ripple voltage. The trouble is, the schematic in the catalog was designed to extract the maximum possible voltage gain from the EF86, for use in microphone preamps, tape recorder playback preamps, record player Nov 18, 2011 · I have built several before around the 12AX7, mainly because the Mcintosh C22 and Marantz 7C both just use those tubes, however I have several NOS Phillips EF86 and am keen to find a use for them. Apr 18, 2013 · I calculated, from the 5. In the case of the EF86, for a line voltage of 250V and an anode load of 100 k, the equivalent noise voltage is approximately 2 uV for the frequency range 25-10,000 Hz. EF806S. Up til now, it sounds like any other valve, no highs, no chime, nothing special. The schematic is from the book "Build your own Audio Valve Amplifiers" by Rainer zur Linde. Share this post: This is a list of Soviet and Russian tubes and their American/European Equivalents. The TAD EF86 / 6267 will work in and EF86 or 6267 position. With its low noise floor and high gain capabilities, it delivers stunning Sep 24, 2016 · but if you tap on certain points with the meter probe it's real loud which is telling me the preamp is working but whatever comes from pin 9 is low volume. OK, so I've just finished a new 18 watt ef86 tmb. Jan 20, 2013 · 2013-01-21 2:15 pm. Feb 7, 2007 · Location: RWC, CA. Cheers! ll Special EF86 vacuum electronic tube for microphone or preamp equipment. Care in the design of the valve to ensure that the electrode structure and its mounting are as rigid as possible has reduced the microphony of the Aug 11, 2010 · EF86 Screen Voltage. This controls the current through the EF86, a relatively small amount of which causes a big voltage drop across the 1 meg plate resistor. Aug 27, 2011 · Hi, trying to recreate the voxac15 pentode chanel. EF86. T. Crafted with precision and renowned Telefunken quality, this tube is perfect for enhancing the clarity and depth of your audio recordings or amplification. #1. Started to believe that they cheat in the demo and use some processor. If you have octal space, I'd use 6SN7. 1V at 200mA for an EF86 heater using the components specified. The first preamp is a Svetlana EF86 preamp tube instead of the common 12AX7A. The power supply is solid state. Dave Dec 21, 2011 · My cathode voltage is up to 1. 6267, 6F22, CV10098, CV2901, CV8068, Z729. Aug 11, 2017 · Dr -- If you get a chance, post some voltage readings for the EF86 position with the two different tubes installed. A 12AX7 triode has less gain than an EF86, but you get two triodes per tube. PT is a spare Weber W025130EU that I had lying around, Choke is a 100mA 50R 3H Mojo 777 I got specially for the job, OT is a custom-built SE (8k Pr 4R, 8R 16R Sec) that I Aug 20, 2021 · Several EF86 tubes from different manufacturers. Indeed as PFL200 surmised, distortion levels increased with input voltage. The Svetlana EF86 is manufactured in the Svetlana factory in Russia, and is designed to be a direct replacement for any EF86 or 6267 type. May 22, 2018 · 2018-05-22 7:50 pm. The tube behaves differently when using standard EF86 values I will try to find a proper values for making this tube behave more like an EF86. Heater voltage 6. Re: Why is the 65 Amps London's EF86 channel so chimey. Looking at the Philips datasheet and taking into account the given values of anode - cathode - G2 resistors and the 217V anode voltage, this tube should work with Av = 170. Offhand, 12AU7 will work. Apr 21, 2004 · AFAIK The EF86 is the only one that was specifically designed for audio use. Care in the design of the valve to ensure that the electrode structure and its mounting are as rigid as possible has reduced the microphony of the EF86 May 25, 2023 · Joined 2011. Messages. I know what you mean about preferring triodes but many people have reported success with pentode voltage amp stages in SE. The plot corresponds to a plate voltage of 250 volts, but it doesn't change much for other plate Feb 22, 2020 · Also, if you triode strap, you may need to rebias the EF86, meaning you may need to change the value of the cathode resistor to give you the bias point you want. For the EF86 under normal conditions, I. TUBEDUDE wrote: ↑ Thu Sep 10, 2020 9:46 pm I use a 5879 in the hot channel of most of my builds. Plate voltage 250v. It is possible to achieve vanishingly small distortion in a preamp stage without any negative feedback - so why would you use it. Sep 2, 2016 · The EF86 has a very low heater-to-cathode leakage voltage, about 50 V. The HT & Cathode resistors have been changed accordingly to give about 1v DC on Cathode & correct Plate voltage. EF86 Substitutes. It does (the 330K) also play into the loading on the EF86 but it's there primarily as part of a F. That could be your problem if you are running AC heaters. What do I have to modify o transform the amp from PP to SE single tube? I attach the Sluckey's 1960 Vox AC-15 pdf. 9k ohms May 29, 2015 · FIGURE 2. Be sure to check both tabs on the fuse holder. 1, page 189), I came across a new flavour. 3V AC (1A). 6V/15V AC(1A), either one 5V AC or two 6. EF86 (Mazda-Belvu) @ Franks Electron Tubes. Mar 27, 2016 · Does anyone know the expected voltage output from the single EF86 RIAA stage? I am torn between Quad22 single EF86 and standard Mckintosh C220 ECC83 twin triode. Grid3 voltage 0V. A twisted pair is recommended since the DC supply still carries the 0. This might be the source of sound changes when testing different ef86 in this amp. Instead of using a cathode self-bias the tube bias is obtained by means of a hight value grid leak resistor (10 MΩ). For the EL84, Va = 295 Vdc, Vg2 = 282 Vdc, Vg1 is of course 19 Vdc and Vk = 28. 6 Vdc. 08-11-2010, 06:33 PM. Base Diagram. So, better order up some 7 pin sockets. May 26, 2015 · The EF86 is a terrific voltage amplifier, but it can't drive loads. I built an amplifier for a customer this summer, and it turned out way better than expected. If the LTP phase splitter grids are pulled too high (and Nov 2, 2020 · You need additional voltage gain between the cartridge and the EF86. You can get that pentode tone by using a dual triode like a 12AX7 in cascode mode. As a consequence I have only one Ei EF86, and tons of PF86 PF86 are a complete equivalent and were often used in TV sets, so should be easy to find. Dec 21, 2011 · My cathode voltage is up to 1. 2 Triode-strap the EF86 Ra=47k Rk=820. This tube has a rugged construction featuring an aesthetically pleasing perforated shield. 5v gridline where plate current is 2mA at 100v plate, and increases to only a bit over 2. An appropriate series resistor in the heater supply will take care of the difference in heater voltage for the PF86. Byrith by connecting the EF86 as triode, was a request, and the easiest way to adapt existing 520s for less gain was to triode-connect the input EF86. 4) EF86 in series boosted by the other channel. Different filament voltage. Close manufacturing specification tolerances and improved processing provide improved reliability and superior sonic performance. Aug 26, 2005 · Does anyone know whether the 6AU6, used in pentode connection as a voltage amplifier, can give acceptable results? For instance, how would it behave as the first stage in a Mullard 5-20 amplifier, instead of a "low noise" EF86? Electrical data. by Garthhog » Tue Mar 07, 2017 2:12 pm. UF86. Hi all, I really enjoyed building a simple valve phono stage using a low voltage design by Karsten and very pleased with the results. Mar 5, 2017 · 1) EF86 channel parallel to the other channel. The Telefunken EF86/6267 tube offers exceptional audio performance with its rich, warm, and smooth sound signature. I used the EF86 preamp channel (no 2nd 12AX7 channel), added my tube based effects loop, and changed output transformers to encourage earlier breakup of the EL84s. Mar 5, 2023 · For large changes of plate voltage the EF86's plate current barely changes which indicates a high internal plate resistance. Dec 10, 2019 · Initially the EF86 would then charge the 500 uF cathode capacitor as quickly as the anode and screen grid resistors allow, which means with several volts per second. But reading the Merlin's book on amplifiers (the hifi version, section 4. The 12AU7 drawn on the schematic is direct-coupled to the EF86 and a 12AU7 might steal a lot of current (from the EF86) but this could have a nice assymetry under overdrive conditions. Variable output voltage: 190-450V DC (100mA) and two 0-30V DC (1. With all these good things going on, why don’t So the voltage gain of a pentode preamp is roughly these two extremes divided by the grid voltage swing needed to create them. The original GEC CV4085 is a special quality version of the EF86 audio voltage amplifier made by the company which produced the famous British KT beam-tetrodes. 0 Svetlana EF86 High-Performance Audio Small-Signal Pentode ELECTRON DEVICES Svetlana Typical operation, Class A Connection, Small-signal amplifier pentode triode DC plate Voltage 250 250 V Screen grid voltage 140 V Cathode bias resistor 1k 3. EF86 triode connection variant. 9k ohms Mar 17, 2022 · RIAA EQ is passive, an EF86 pentode tube is used for each channel's input stage, a 6N6P dual-triode for the output stage, and there's no overall loop negative feedback. line voltage of 250 V and an anode load of 100 k, the equivalent noise voltage is approximately 2 μV for the frequency range 25-10,000 Hz. by dehughes » Sat Nov 25, 2006 5:28 pm. (or not?) Any comments/ideas? (The EF86 voltage notes from an earlier build which ran the same gain stage setup are attached FYI) 3) Tone stack. But there is actually a solution for making it work: 1 Move the volumecontrol to the input. e. Resistance in cathode circuit, 500 Ohm. B. TYPE: CV4085 (Special EF86) B9A LOW-NOISE TYPE FOR MICROPHONES TYPICAL APPLICATION HEATER CIRCUIT The voltage polarity of the heater pins in the Phædrus Audio EF86 TRIODE SupertubeTM must be respected. Thanks. The Valve Wizard. According to the databook the EF83 was also intended for audio. 6DJ8 or other tuner twin-triode should work too. 8. The Phӕdrus Audio CV4085 (Special EF86) SupertubeTM measures <1. Sure, adjustments on the controls have to be done when switched. Mostly, you would just simply cap couple the signal from an EF86 anode to the grid of Jun 9, 2004 · Sep 24, 2004. line voltage of 250 V and an anode load of 100 kΩ, the equivalent noise voltage is approximately 2 μV for the frequency range 25-10,000 Hz. D. Different rating or performance. 3 Make the second stage a CF, DC connected to the first, and use ECC82. #3. Apr 22, 2006 · As to your ideas about driver and voltage amp, I would think EL34 in triode-connected CF operation as a driver would be good and an EF86 voltage amp would also be good. 3 volt supply is putting out voltage. Took me about 4 days and 3 nights from scratch (chassis bent on my new bar brake). pb dk ce li io zb xx lq tf iu