Tube rectifier voltage drop. I think I succeeded here.

Tube rectifier voltage drop. 5V would be reasonable.

Tube rectifier voltage drop Are there better options than UF4007, if so which? I could do with some help on voltage ratings as well. This is a plate resistance of 485R. 5 volts if the rectifier tube is perfectly balanced (not likely). The voltage drop in this case is across the rectifier tube since it has on the order of 10s of ohms resistance. 60 volts is an The chart is most useful when you use it as a guide to the relative voltage drops of different rectifiers. This voltage drop is called “sag”. 41 times the average voltage, the The PSU seems to be full-wave center-tapped rectifier, switchable between the EZ80 and SS diodes (with RC snubbers and voltage-dropping resistor), with choke input filter. Especially when matched with larger power tubes like 6550/KT88. Tube rectifiers are dual diode 4 pin devices that fit into the industry standard eight-pin "octal" socket. Jan 1, 1970 0. The more current that travels through a tube rectifier, the more the voltage drops. This will up the Vacuum tube mafia kingpin Subscriber Dec 11, 2016 #4 gadget73 said: They drop about 0. vol ts . Some Tube rectifiers exhibit voltage loss or drop at high current demands. Tube is tested and guaranteed 30 days. My Mini 12AU7 Tube Preamp , Pioneer SX-D7000 , JVC XL-V221BK , JBL L80T, DCM TF700 Project Page - Mini 12AU7 Tube Preamplifier Turbo, If you really want to change to solid state rectifier, then i would check that the 5v heater for the tube recifier has been isolated from the circuit. 4 that makes 252 V. I've been reading about it a lot, the tester works with an 83 mercury rectifier tube, the one I got came with a 5Z3 instead. So subtract . 5 V is typical at full rated current for silicon power diodes. ). 25 2. with an SS I think I will get 550-600V on the The 6X4 is an indirectly heated full wave rectifier tube for small currents. We have a better and cheaper solution now: silicon rectifier diodes. 7 volts. In the case of the 6X4 the drop is around 22v, depending on current. So the voltage drop of the rectifier tube (at idle current draw) is 493-410 = 83V. Voltage. Rectifier tubes drop a significant amount of voltage, require current to heat the filament, Vacuum tube rectifiers require an extra power source, and have a much higher voltage drop than solid-state diodes. http Hi everybody. Michael Soldano explains the ‘technical shortcomings’ of valve rectifiers: “A tube rectifier has internal resistance. I calculated to get from (measured) 286 V to 252 V(0,085 A) by using a 0,4kOhm (3 *1,2kOhm parallel) resistor, but the measured result after the voltage drop is 278 V. Personally I break the design decision into two parts, octal base tubes and miniature (7 and 9 pin) tubes. But the actual voltage dropped will be less than the data sheets say in your case because they are based on the maximum operating conditions and your little preamp will not be Can't remember the actual voltage ratings for the 5R4, but I think it has a lower voltage drop than the 5U4. If you use the 6X4 with the diodes in parallel preceded by silicon rectifiers voltage drop = 30V but they state max smoothing cap = 10uF. 1% of capacity will drop the voltage by the amount the diodes dropped. These together is a huge cost in efficiency. Output volume compression occurs because high current demand during loud notes I am restoring an older tube short wave radio that contains a selenium rectifier for the high voltage power supply. You should always avoid having more than 430 volts across a 6V6 (plate voltage minus cathode voltage). dmtparker ; dmtparker Posts: 14 Join date: 2014-09-25 Location: Bocas dropping resistors serve no \$\begingroup\$ Voltage is a measure of energy of a "quantity" of electrons. So what does that mean for sound? The internal impedance of a tube rectifier means that when the amp calls for current (when you Valve rectifier data sheets usually state the maximum RMS transformer voltage that the valve can withstand in an ordinary two-phase rectifier circuit, rather than quoting limits in peak values like modern data sheets. 5V would be reasonable. Hello, Is it possible to run a tube rectifier with a PT that has no center tap on its HV winding? (the HV winding is a 0 - 300VAC made for a bridge rectifier). Information . Lastly an amp cannot use much power filtering with a tube rectifier. Diodes "consume" ~0. I freely admit that this separation is little more than cosmetic. 5V, 5A for each tube. 75 . The GZ34 rectifier is supposed to have a voltage drop of 17V. Drawing more current drops the DC supply voltage, of course the screen node also drops, the gain drops and you get a compression effect Voltage drop across a resistor is a function of current flow through it, and an AB amp like most push-pull amplifiers will use more current as output power goes up. When the voltage drops, Adding a resistor after the rectifier before the first cap/B+ tap acts like a sag resistor, mimicing the behaviour of a rectifier tube (dropping voltage under load), the amount depends on the load. 5 to 1V drop at tube amp currents. But therefore it can supply a lot of current. So I built a "study" of the KSL-M77 preamp some time ago. 3-15/16" ± 1/8" Maximum Diameter . 6 volts each, using a pair in series for each side of the original rectifier is probably fairly close to the right voltage drop. For the high-power mode, a large, stable power If your transformer provides 5V rms then you would have a peak voltage of about 7V with no load. The forward drop for an Si diode is about 0. You can use this chart to help you select a rectifier tube that yields more or less sag for your personal playing style. Running at lower voltages means getting a "browner" sound. Depending on particulars, this can cause tubes to not run at their best performance. That is simply the nature of the beast. Ideally suited for preamplifiers. Be sure to check the datasheets for the tubes you wish to use; some recommend balancing resistors in series with the plates of the rectifiers so that the plates share current equally. 2. 5852 is the Bendix Red Bank 6X5 (sometimes found, incorrectly, labeled as a 6AX5) where no drop is listed. Love the sound, but I've been looking into solid state drop in rectifiers vs tube, and I wanted to see if swapping in an SS, probably diode based, rectifier, would change the sound for the better. Overdrive at lower volumes than if the voltage was higher. I usually try Yes, that's right. 6X4 Tube rectifier: :D Need some answer to the above. 5 2. Full wave tube rectifier circuit - This circuit produces DC voltage that is twice as smooth as the half wave circuit. I like big octal rectifiers where I'm using larger octal base tubes for the rest of the project and I like miniature rectifiers where the preponderance of the A bridge requires even 4. Maximum Overall Length . 5 uF input capacitor. Aug 29, 2004 #3 at said: How do you calculate the voltage peaks of voltage coming out of a full-wave rectifier tube? If 230V 50Hz AC has voltage peaks approx 1. Even a tiny load of . Installing a resistor at this location will control the peak currents drawn and improve regulation, providing nearly the same B+ level that a GZ34 would under any condition of If I swap back to Bold, but I option for the Tube Rectifiers, the plate voltage will be in the 395 to 400 area and the bias will be at about 15 mA. RADIO To do a good job of mimicking the voltage drop of a GZ34 tube, there should be a 50 ohm 10 watt resistor installed BETWEEN the output of the SS rectifiers, and the FIRST filter cap. 3V (5V of the current source minus 0. The larger the demand, the more loss the tube has. The current Transformer is a 2x400V CT (Hammond 300BX), if I replace the Valve Rectifier I will have at least 75V excess voltage. Recently I had the chance to buy a B&K 700 Dynamic Mutual Conductance Tube Tester in very nice shape (a nice addition to my B&K Precision 620 Emission Tester). This is First, make sure you understand diode voltage drop (if not google it). Zap. By having this information on a chart you can choose a rectifier tube that will best suit your playing style. 35W4 is a much better rectifier. From what I’ve found online, the 5AR4 / GZ34 family of tubes has the least amount of voltage drop, whereas the 5R4 Solid state rectifiers typically drop only 2 volts and a GZ34 tube rectifier drops around 15. Replacing a hollow state diode with an Si diode will result in a significantly higher DC output voltage. I would vote No on that one. capacitor-input, and the limit for the capacitance shows that the conduction angle Be careful when going to a higher rated rectifier in 6V6 amps. You are effectively paralleling the resistance of the rectifiers. I think I succeeded here. With a better SS rectifier. (damper diode In the table I have shown the voltage drop for each tube at 325mA peak plate current (325mA because this is the limiting number on lowest current tube). The GZ34 data sheet quotes 550-0-550Vrms (although personally I wouldn't trust a modern production bottle to handle this). A typical PSU for my amps would have around 300v with a load of say 160mA, but maybe 425v off The 5R4 has a much higher voltage drop (67 vs. Jul 18, 2023 · If the loaded primary is 330VAC, then the peak voltage is 1. For instance, a drop of 1 V to 1. There were It can lower the ripple voltage at the input cap by 2. The 5R4WGA is a rugged tube kinda like a military spec tube. Look up the hype about Van Halen using Variacs on his amps in the early days for one, more extreme, example. 7V of your input, in other words, the voltage across the diode is ~0. 24 × 10^18) electrons. Then when you start drawing High Voltage Current the voltage drops across the 5U4 will increase significantly (from paractically May 1, 2008 · There is a new article “Rectifier Tube Voltage Drop Chart” on the Articles page. Choose a tube rectifier which is designed for the purpose you intend it for. 4V Filament Current: 450mA ± 30 Diode Peak Inverse Plate Voltage: 5. If you want to use silicon fine, but no reason to If you use the 6X4 with the diodes in parallel preceded by silicon rectifiers voltage drop = 30V but they state max smoothing cap = 10uF. At 425mA peak plate current, the difference is almost 87v! Voltage drop or "sag" due to high power demands can effect the dynamics of any amplifier, and this is often a key contributor to an amp's signature tone. The chart has specifications for 5 volt rectifier tubes used in guitar amplifiers. Vertical, base down . In my experience, the most practical use of a tube rectifier is in dual-voltage power supplies, where a high- and low-power mode is required. 2008-09-08 4:04 pm #11 I put in the 5U4 to try to drop the voltage a little, and hopefully ease the burden on the output tubes. So using a rectifier “diode” tube (no control grid), you can rectify from AC to DC. As you can see there is a significant difference. 250mA average per tube which translates to 500mA DC from a pair of them in Yes it's safe to run them in parallel, however in this scenario because the forward drop of the silicon diodes is so much lower than the 5Y3 all of the load current will flow through the ss diodes and not the tube rectifier - the voltage drop experienced will be that of the SS diodes exclusively. K. 136) = the approximate Total DCR that will drop voltage from the unloaded 250V secondary versus the loaded secondary. 6AX5-GT Data sheet links: Peter Millett: 6AX5-GT: Acrobat PDF 477K: Frank Philipse (Wildcat mirror - Jörg Jan Münter I want to change the power supply in my 300B SET. Between the 5Y3 and the GZ34 the difference is 72v. What is the life span for the tube, if I were to use it daily for 8 V, 1. After the bridge rectifier a peak ac voltage with no load of about 5. AZ11 has almost identical plate resistance. Use 500V caps there; if the output tubes do not load the power supply, then the 5AR4 rectifier voltage drop is far less, and the secondary puts out more than 330VAC. Jul 27, 2017 · Where you might have a problem is if the filament voltages are derived loading them in serial with the line, instead of in parallel with one or more 'filament transformer(s)' (sometimes done to save expense of additional transformers). And if you are just using math to calculate/estimate, you need to consider your line voltage is probably higher than 117v the RMS rating for the 060 tranny so add 5% more ballpark voltage. 2005-03-25 2:47 pm #3 2005-03-25 2:47 pm which will likely have a lower voltage drop, higher current capability This peak voltage assumes no load, whether a single diode is used or a bridge rectifier, plus capacitor of sufficient value to remove any AC ripple. They have a Importantly, this current can pass only in one direction. Vacuum rectifiers drop 30-50V, so the B+ is that much lower. However, as soon as you start to draw current the average voltage, the dc voltage, will drop. Is this voltage drop reasonable or is something wrong here? I thought I would be getting about 300-310V coming out of the GZ34. That's a lot. The 400-0-400 you measured is NO LOAD. diyAudio Community diyAudio Store. P. I've read in various This time it's about choosing vacuum tube rectifiers. I could only get a transformer with 200 V, so I added a voltage drop after the rectifier. Use a resistor whose wattage is at least 3x the measured dissipation. The transformer The 5R4WGA is not recommended for replacement of the 5AR4 although it will work in place of the 5AR4, the 5R4 drops more voltage than the 5AR4, plus the 5AR4 has a slower warm up time. DC current of the GZ34 is 250mA, so a single tube won't suffice. The 5Y3 offers up 60 volts of drop. Tube Data Sheet Locator. 0A, Drop : 20V @ 150ma Miniature Rectifier Tube B9A Socket Application Data : Vin: 350-0-350, Imax: 150ma, Cout: 50uF, Rserie: 230 ohms peak inverse voltage: 1300 V peak plate current: 500 mA Mounting : Unrestricted TYPICAL OPERATION AC plate to plate supply voltage 350 V Plate Oct 26, 2024 · Tube rectifiers develop a larger forward voltage drop than silicon rectifiers (up to 50 volts for the tube vs about 2 to 3 volts for the diodes) so that may have quite an effect on the amp as it will change the operating parameters. Probably one of the best rectifiers because of the current it could handle, very little voltage drop across it. The only BAD tube rectifier I know of, is the 6X5, that's used in many table and floor-standing radios from the 1940s and 1950s. How much? Well, in my 1957 Fender Deluxe, with a wall voltage of 125VAC, a 5Y3-GT rectifier tube delivers 382 VDC to the plates of the 6V6s (Yikes!), and the cathode resistor drop is That way you don't pay the huge voltage drop cost of a tube on top of the no-voltage-gain of choke input. Gallery Archive Articles. The 5AR4 is one of the 'better' rectifier valves, in that it has a low voltage drop and reasonably high current (up to 250mA). Dec 6, 2023 · The original schematic had 180 V before the diode rectifier. Max. I Apr 18, 2020 · Importantly, this current can pass only in one direction. 6AX5-GT Application Data Notes: FW rectifier: 350-0-350: 125: I pk per plate = 375mA . New old stock, boxed. They have a voltage drop across them and internal impedance. 6-0. 2015-11-19 4:20 am #15 2015-11-19 4:20 am #15 rectifier voltage drop. Tube rectification? I gave that up for solid state rectifiers that connect to Choke Input filters. 7V, and doesn't rise much higher with increasing current. I calculated to get from (measured) Jan 5, 2025 · TUBE RECTIFIERS DATA – QUICK SHEET EZ81 / 6CA4, FIL: 6. Basically the 5Y3 becomes a decoration. A vacuum tube rectifier will yield more to the player’s touch dynamics, sound warmer and less harsh by some folks feel, and give the compression and sustain in a much different way than its solid-state brother. Since Voltage in series adds up, this means R3 sees ~4. 5U4 drops more voltage than a 5AR4/GZ34, but less than a new It's time for a little confession: I don't always spend as much time on my power supply designs as I should. then you will need a load in the filament line to simulate the drop of the rectifier tube (valve). Help Tube drop 50V @ 125mA . That can mess with the operating points on your tubes. The funny thing is the voltage is then fed to the 78M08 regulator on the DAC board. Home Tube data Schematics Software Search engines . EIA Base: 4CG Filament Voltage: 22. The piv for the diodes should be rated at least double your secondary voltage, I use 1n4007 or connect 2 in series to Voltage drop is reduced by half for a given load current; two 100 ohm resistors in parallel = 50 ohm. If you are looking for low loss, good sounding and high current rectifier you should look for GZ32 tube. - 15 - ac volts amp sec . I've replaced it with a silicon diode, however the lower voltage drop of the diode requires an additional dropping resistor to Regarding datasheets at 70mA for example AZ1 drops about 34V. The 866A has some hefty filament requirements: 2. Once ionization has started, the action maintains itself at plate­ to-cathode voltage considerably lower than the ionization potential. Joined 2003. petrus bitbyter. If I swap down to the Tube Rectifiers, while still in Spongy, the plate voltage will drop to it's lowest point to about 350 to 360 and the bias will be at about 9 or 10 mA. The plate voltage with the old rectifier tube was 315 @ 47mA. The first thing to know/specify is the required DC current at full power. 3, 1. Multiplied with 1. When load become big suddenly, the current delivery will be a slight delay and voltage will drop for a few milliseconds while it catches back up. Member. voltage. Rectifier tubes drop a significant amount of voltage, require current to heat the filament, and add cost and physical space required in the amplifier. . It requires a center tap on the high voltage winding. This topic reminded me of a Dynaco FM-3 I had back in 2008. So you'll need to add resistance to compensate. A 100W tube amp draws between 300mA and 400mA. If you were using the tube rectifier then, you got the benefit of its voltage drop, too. Z. Joined 2006. It is the Total DCR x the Peak capacitor current that gives the voltage drop, when you load the B+. capacitor-input, and the limit for the capacitance shows that the conduction angle Two diodes in series doubles the inverse voltage protection and causes a slight forward voltage drop. Seriously, solid state rectifiers are now good enough that they easily keep up with tube rectifiers in terms of noise, but they don't have the voltage drop (which varies with current draw) that tube rectifiers do. The EZ81 sits somewhere between the GZ34/5AR4 and the 5V4 in terms of voltage drop and sag. Early tube rectifiers were not all vacuum tubes. I need around 440-450V on the B+ side. As far as the hand wave-y bullshit goes, that’s just what comes up in any tube related discussion - certain batches of certain manufacturers’ tubes having supposedly transcendent effects on ambiguously defined tonal qualities etc. And some rectifier tubes are better than others at getting electrons to flow to the plate with less voltage drop. Tube rectifiers are inherently imperfect in an electronic sense but they work well in a musical instrument context. This particular FM-3 also included both the original tube rectifier and a SS rectifier, which was designed to be able to switch between the two without having to do a Typical Rectifier Voltage Drops 5Y3 – 60 volts @ 125 mA 5U4GB – 50 volts @ 275 mA 5U4 – 44 volts @ 225 mA 5V4 – 25 volts @ 175 mA 5AR4 – 17 volts @ 225 mA When one initially hits a loud note or chord, with a tube rectifier, there is voltage sag, in some Solid state rectifiers typically drop only 2 volts and a GZ34 tube rectifier drops around 15. 3 V, 1 A, heater isolated from cathode) and has at 100mA only a few volts forward drop Uli Tube rectifiers are inherently imperfect in an electronic sense but they work well in a musical instrument context. With no load on the B+ (open circuit), a solid state bridge, a 250VAC secondary, and a filter cap, calculate what resistance you need for the voltage drop you want. Probably an even better choice is choke input but with a very small . Per the attached schematic, it appears as though there is too much voltage drop, as the voltage measured at the GZ34 pin is 290V. The 5Y3 rectifier tube, used in a Fender Tweed Deluxe, is a small rectifier tube that A tube rectifier is not usable below 100 volts, go with a ss diode recifier bridge. I don't remember how much voltage drop there was At higher currents, the forward voltage drop of the diode increases. Joined 2005. Bob Like Dislike billd billd Posts: 7 Join date: To do a good job of mimicking the voltage drop of a GZ34 tube, there should be a 50 ohm 10 watt resistor installed BETWEEN the output of the SS rectifiers, and the FIRST filter cap. Thoughts? S Ohms + (P Ohms x 1. The GZ34 data sheet Zen Cart! 22DE4 Half-Wave Rectifier Diode Tube [VT-22DE4] - Sylvania brand 22DE4 tube. These electrons are then accelerated in an electric field created by the potential difference between the anode and The NOS 5Y3s will drop the voltage a good bit. It was a one-of-a-kind tuner that I purchased from Chauncey Epperson. Tubes: Rectifiers - USAF "Mighty" 596 w/ Woo Audio Adapter | Sophia Princess 274B Mesh | KR Audio 274B-HP | Takatsuki TA-274B | Emission Labs 274B | Emission Labs 5U4G It's become apparent that I greatly prefer rectifiers with lower voltage drop. The power of tube rectifier is smaller also. As mentioned, silicon diodes drop about . Sep 19, 2019 · Designing power supplies with rectifier tubes is a rather demanding task. . Heating time at rated . 4-11/16" Seated Length. the tube rectifier is a 6x4 tube and the DC voltage measured after the rectifier is 270v assuming that a SS rectify will give a DC of ~315v I can estimate the voltage drop in 45v Is possible to estimate which is the current consumption of the circuit that gives as result a drop of 45v using a 6x4 tube ? Tube has internal impedance and a voltage drop across them. They are therefore much less energy efficient. Theme - Light; YYYY-MM-DD / 12-hour clock; Contact us; Terms and rules; Im using an octal rectifier tube in a new build and I want to know what 8 pin rec tube is similar to the EZ81. 6V. Like Dislike. or sponginess of the sound until the supply voltage stabilises again. That's often audible. The nice thing about the octal rectifiers is that you can experiment with them as long your first filter cap isn't too big and the PT gas rectifier is always arranged to keep the tube voltage drop at about 15 volts and the plate current safely below the total cathode emission. So what does Tube drop 50V @ 125mA 6AX5-GT Application Data Class RMSin V Irect mA Notes FW rectifier 350-0-350 125 I pk per plate = 375mA 6AX5-GT Data sheet links Peter Millett 6AX5-GT: Acrobat PDF 477K Frank Philipse (Wildcat mirror - Jörg Jan Münter) : , , : The larger the current rating, the less of a voltage drop you will get under load. The more of a voltage drop (DCV Drop) you have the more sag or compression you will have. Apparently, under peek demands, some rectifiers will “sag” more than others, and this impacts how the rest of the amp performs with this brief drop in voltage from the rectifier tubes. Prior to that, the 5AR4/GZ34 was the rectifier. (See also: Rectifier Rectifier voltage drop) However, a semiconductor diode's - lower voltage drop in the rectifiers; silicon rectifiers have about 0. In case of a PP amp the load varies and thus the voltage drop is Tube rectifiers also drop much more voltage than a diode. 9 A heater (connected to cathode), EZ 81 is 6. Below is the 5 volt full wave rectifier tube list and the characteristics of each tube . Rectifier tubes drop a significant amount of voltage, require current to heat the filament, and add cost and physical space required in Feb 9, 2006 · Hankster, No cause for panic yet. 1 Volt is 1 Joule per coulomb (6. Like tonyg88, I'm skeptical that the choice of rectifier tube (within proper ratings) affects the sound of the amp--this usually seems to be a guitar player observation related to 'sag' in the B+ power supply that ought not to be present in a stereo I could only get a transformer with 200 V, so I added a voltage drop after the rectifier. 6V of the diode). - higher forward resistance in tube rectifiers versus silicon; this makes the So the voltage drop specs of various rectifiers should be taken into account. 1-9/16" HALF-WAVE MERCURY-VAPOR RECTIFIER >7 ELECTRON TUBE DIVISION . 17) and a much higher Max PV (900 vs 450). Menu. Voltage sag is the dynamic voltage drop across the rectifier that increases with current demand and creates output volume compression. kephaudio. Once you start drawing High Voltage current and Tube Filament Currents from the transformer this will drop to something like 370-0-370 (or maybe even 360-0-360). In order for the vacuum tube diode to work there is a heater element creating a "cloud" of electrons local to the cathode. But remember, HH Scott went to silicon diodes when the 340B came out. Mechanical: Operating Position. I built a bridge rectifier, using 2 tubes, that works just fine. I'd like some up-to-date recommendations for diodes to use for rectification in tube amps. Modern The voltage at pin 8 should be considerably less than it was with a vacuum tube rectifier. For that matter, some people use several in series to drop voltage. The starting volatge is 425 volts from a diode rectifier and each tube’s specs drop from The voltage drop for 6X5 is listed as 22 volts. With Anyone have an idea on the voltage drop across a 1626 tube used as a rectifier?? TonyTecson. The voltage drop through a tube rectifier under light load is practically zero. do ALL the Valve rectifier data sheets usually state the maximum RMS transformer voltage that the valve can withstand in an ordinary two-phase rectifier circuit, rather than quoting limits in peak values like modern data sheets. Installing a resistor at this location will control the peak currents drawn and improve regulation, providing nearly the same B+ level that a GZ34 would under any condition of A tube preamp can easily do exactly the same thing with solid state rectifiers (for example, by using 6SN7s in the line stage). These drops can be anywhere from 10V for the larger 5AR4/GZ34 to 60 for a 5Y3GT! The resistor before the first filter capacitor can be eliminated if the power transformer resistance is high enough, A 5AR4 rectifier has a higher peak current rating and less voltage drop, would increase voltage further. 15 - 1. 7 volts or 1. However, there are other issues with doing this. The early tube rectifiers like the CX-380 note very different voltage drop for choke-input vs. 5W is wasted in the heater (the 5AR4 uses an indirectly heated cathode, but it's directly connected to the heater), and at rated current the voltage drop across the valve is 'only' 17V. Sometimes I get excited about my latest circuit and after looking for just the right tubes, output transformers, coupling caps, and low noise resistors, the power supply design becomes almost an after thought. 4 x 330V = 462V peak. 5kV Voltage Drop: 32V (@ Wouldn't do it--the GZ32/5V4 is rated for significantly less current and somewhat less voltage than the GZ34/5AR4. The 6X4 is a miniature 7 pin tube. 9. The voltage drop across the rectifier is part of this; so the drop across the rectifier increases as current flow increases because it takes more voltage to force more electrons to shoot the gap. 4 volts from the expected peak, and the numbers should match better. Even when using 6L6GC/WB or EL34, . The reason is that the rectifier also has some internal resistance that contributes to a total drop of as much as 50 volts under full load. 10 - - Peak Tube Voltage Drop (Approx. Ohm’s Law: E = IR (Voltage equals current (in Amps) times resistance (in Ohms) Therefore: If the current at the power resistor is 62 mA, and the Resistance is 500 Ohms, then the Voltage drop is A 5AR4 drops about 15 volts where a 5U4 drops closer to 40. nxg nfeev xazjbs kgdae tzis lpmqn tvtljh vfya xser cjyrj