El84 plate dissipation chuck But at plate volts over about 360 EL84's start to lose this character and over 390 sound quite ordinary IMHE. Dissipation is 8. You must re-calculate after changing values by clicking any Calculate button. But with the VariAC, I lowered the MAINS voltage a bit, down to 425V. Enter the Plate-to-Cathode Voltage which is the DC voltage measured between the plate and cathode tube socket pins. But the main way of dissipation is IR rays that go through the I have a question about the B+ on an EL84 in single ended configuration. They don't lie. We did choose the thickest glass option and most heasvy construction like the Russian EL84M and sonically most promising cathode The Penta Laboratories EL84 is a power amplifier pentode designed for use in the audio frequency power output stage of television and radio receivers and in high fidelity amplifiers. But it isn't near the quality of a Mullard EL84 or 7189. Heaters were at 5. s. The 7189 is the tube I mentioned earlier, but could not remember its part number/name 7189: Plate dissipation 12W max. Post Cancel. SandAndGlass likes this. I tested the cathode Been losing sleep over screen R values in an AC30 type build. While not a 6V6 I've run 50C5 types at over 300V on the plates which is far, far about any design curve you see - but I was careful on I've built an EL84 P-P in UL (7. ) It may be biased a little cold to some, but let your ears be the judge as to if it sounds good at that level. EL84 can mostly work very well with a cathodyne phase inverter, The class A amplifier looks like a waste because it runs hotter at 11. Home; Forum; Papers; Market; Tubes + Tr; Sounds; It's dissipation power was increased It lists maximum plate dissipation at 14w vs 12w for the 6BQ5, 7189 etc. 76 watts of Plate Dissipation. Telam and Polam EL84 - Two wild and crazy tubes! I see this all the time. EL84 12,0 VaMax plate voltage E84L 450 (volt) VaMax plate voltage 7189 400 VaMax plate voltage Mul. e plate voltage pin and which ones are screen resistors etc. Level 5; Posts: 5083; As I suggested now you can select low Pc EL84's which should let the amp operate cooler with the same Rk in place if you're disinclined to experiment With 350V+ plate voltage and a 120R cathode resistor the plate dissipation will be 15W. But i ended up with literally hundreds of tubes that i dont have much use for. Hi can someone tell me how to check bias and dissipation etc on the el84's. png. 70% of 12 watts is 8. martin manning wrote:Subtract the cathode voltage from the plate voltage to get Va-k. Ive never seen one showing more than 12w max plate dissipation. Attachments. a low power "version" makes absolutely no sense, and is a very dangerous thing to be offering their current EL84 users. The schematic of my 1967 Harmony H415 idles at 299 (net) plate volts for around 12. Max plate dissipation is a design center value for continuous operation, not an absolute max, so the EL84 is run hot as it should be, but well into specs. Note that this build is using fixed bias and Toroidy EL84, 8k output transformers in UL connection, with regulated plate supply. very good sounding tubes is toshiba EL84 if you can find NOS tubes from philips not good from me,fast die in 100% anode dissipation ,my amp have very hot bias. This results in about 47mA bias current per tube, making the plate dissipation around 13. If it doesn't I'd progress as follows until you find one to your liking: 220R 200R 180R. Also the 7189A has internal connections to pins 1 and 6, so you need to I ordered new J/J EL84 & EZ81 tubes, which came in today. RNELEE New member. I biased the 6AQ5 tube to 12W plate dissipation and have not had any redplating or other problems. p. Giving him the benefit of the Data sheets are like Shakira's hips. output pentode max 22,0 max 71,4 max 77,8 Base: NOVAL uf = 6,3 V If = 0,760 A Typical Characteristics: ua = 250 V ug2 = 250 V ug1 = -7,3 V Ia = 48 mA TrANsfer ChArACTerisTiCs pLATe ChArACTerisTiCs A. EL84 screen max is 300V and 2. volts Plate Voltage. I tested too many EL84. 4/ plate supply : 250-300VDC required. EL84 = 6BQ5 PREMIUM HOLLAND EL84. Since they are 1k Tube EL 84 or Röhre EL84 ID412, Vacuum Pentode, Noval, 9 pin miniature (USA pico-9) B9A and Power/Output shown. What was your plate dissipation at 360V with a 100r cathode resistor? 0 x Top. Can you recommend a euphonic pentode with plate dissipation comparable to paralleled KT90s at a B+ of 400V--say about 100W per tube? I need pentodes so I can switch between Ultralinear and Triode mode in my cathode-feedback design. Filament voltage, V. Our observation: We’ve compared these to all of the classic European EL84’s, Calculate Plate Dissipation Based On Plate Voltage And Cathode Current Readings. The E84L that you speak of by Siemens is a good tube. 76w / 12w = . The best sounded tubes for me is TELAM-POLAM EL84,made in poland ,rugged tubes. It is very similar to the 6L6 sound but with less power. Occasionally over the years I might make a little progress here or there, This results in a quiescent plate dissipation in the output tubes of (320V-10. That matches what you get out of real life amplifiers made when that tube was widely used. I assumed as much. It's got relatively low plate and screen voltages at about 310 and 304 with respect the cathode at about 10. Comment. Some tube grids might warp. That is what you should use to calculate plate dissipation Pa. Voltage is high, but bias current is low. I personally like my tubes biased at 60% or 70% of static dissipation and the Sovtek EL84 performed well in this range. (If you’re in for some preamp-tube-swapping fun, 5881 is a beam power pentode with a maximum plate dissipation of 23W in the classical short bulb. 45mA (15/330) and plate voltage is 305v (320-15) which means the plate dissipation is 13. E. Many amp designers run these tubes at 400V to 430V on the plate. Marshall-1974X-18W-Schematic. This as function of • Quiescent Plate Dissipation – pdQ = (VPQ-Vk) × IpQ = 11. When I was shopping for tubes for my Fisher 600, Jim actually suggested the Sovtek because they would deal with the voltages involved and work out as a 7189 sub. What you really need to watch for is the plate dissipation. Developed by Philips in 1953 for use in the british Mullard 5-10 amplifier, the EL84 came to prominence when used in Watkins (and later the Vox) amplifiers preferred by many British invasion bands of the 1960s. The amp has got just 1 tube per channel for over 2W power (triode Came across this while searching for something. GE EL84 are far superior and I have tested many EL84s. Thread starter Cassiel; Start date 2006-12-09 4:18 pm; Status This old topic is closed. The closest thing to EL84/6BQ5 you can find in a noval based compound valve certainly is the pentode section of ECL86/6GW8/PCL86/14GW8, which can be viewed as a plate Pd derated (9W vs. Specifications Heater UH 6. The EL80/6M5 is ~90% of an EL84, plate dissipation of 10 watts, not 12, and need to be a little cautious of screen voltage. Found some Polam / Telam (Polish factory using Philips machinery - regarded by some as the best Philips tubes ever made) and some Tesla EL84's. At EL84's 12 Watts max plate dissipation and 300V, that is 40mA. 4 W plate dissipation and has got less power but distortion is lower nearly up max power, So, your amp appears to be drawing exactly the recommended maximum (i. It was similar to the EL84, but the screen was only rated at 250V and 1. That will allow biasing the tube to about 40ma, Also it will determine how much plate dissipation there is (without screen current). 0194a = 7. After installing a trim pot, and re-biasing down to 70% PD, the amps sound just as good, and I don't have to replace tubes. 1 Watts That seems too high. We might idle with bias of -10v at 300v on the plate: G2 current is 2mA. Chosen by Matchless for I installed a new EL84 from JJ and decided to check the plate dissipation. Plate Dissipation. JJ Electronic EL84 Factory Data Sheet: EL84 Factory description: Gold plated control grid for improved fidelity and a plate dissipation of up to 12 watts. To get the 7189 designation you build a tube that will handle both higher plate voltages and increased current. 7W (note that the EL84 is only rated at 12W max plate dissipation). A. 7W. Plate dissipation (Watt) 11. You have used the cathode current which is plate + screen current so you have calculated the plate + screen dissipation at 17W. Best regards KJH DC plate voltage 400 V Grid no. Logged On the right track now<>< sluckey. Joined 2015. 24V. Bias represents a 6P14P are more powerful than standard EL84 (14 vs 12 W of plate dissipation) and very linear (I use them for hi-fi), and you can find them with different selection of guaranted workind time: 6P14P - 3000hr; 6P14P-V - 1000hr; 6P14P-EV - 5000hr; 6P14P-ER - >10000hr; 6P14P-K - 3000hr like the standard one, but more mechanically robust (originally designed for I'll check plate dissipation and amp performance at both voltages. mA Bias. p. Member. 76 A Maximum Ratings Plate Voltage 500 V Plate Dissipation 12 W Grid #2 Voltage 300 V Grid #2 Dissipation 2 W Cathodic Current The 7189A is an improved version of type 6BQ5/EL84. Swapper’s Delight Swapping out power tubes is much trickier than with preamp tubes. Matchless spitfire el84 dissipation . 1) It is less expensive to make an amp with four EL84's. Would it be necessary to Keep plate dissipation well below the 11 watt maximum Russian 6P14P plate 250V, screen 250V. Not the other way around. If your amp wasn't asking the most from a EL84 as set up, this could be a possible alternate. Plate dissipation is low at 10 watts and screen dissipation is at 1W. ReVintage_SE-EL84-Schadeode_EXPERIMENTAL. Measure the voltage across the screen resistors to get the screen current Ig2. In general, the EL84 output tubes would last several months of moderate use, and then crap out. The EL84 absolute max plate voltage is 550 VDC, this makes me think that those tubes were failing due to excessive power dissipation rather than to the high voltage, OTOH it' s also true that, AFAIK, the mains voltage in the US has been raised from 110 to 120 VAC and this could give rise to some reliability problems on "borderline case" designs like this. One seller on the web says the 6P14P-EV military version is a 7189. Would I also want to put big screen resistors? The 5763 seems to be a perfect sub of the EL84 . EL84 Pd should then be down to about 12W. 65 or 65% I own several Blues Juniors. Known to be a very powerful 6V6 due to its robust construction. A+! The Nomad 100 would normally be running 480V plate voltage. Pin 7 Plate: 425VDC Pin 9 Screen: 415VDC Pin 3 . The datasheet on the JJ EL34's I'm using to upgrade a Marshall 1974X handwired 18 watt combo to ultralinear says maximum plate voltage of 300V. The Sovtek EL84M's extended voltage tolerance, improved plate dissipation, and rugged construction make it equivalent to the RCA 7189. Power dissipation at the plate, W Power dissipation at the second grid, W fixed bias self - bias (at: filament voltage 6. For 9-Pin tubes like the EL84 the plate is pin 7 and the 56k tail load and plate load resistors work well with 6V6 and EL84 power tubes. 50ma is the maximum recommended sustained plate dissipation for the EL84 in SE Pentode operation. F. At 300 volts plate-cathode it's still at a comfortable ~10 watts plate dissipation and you'll get more power out of it. 2. 2w. 1 Resistor fixed bias <300kΩ Grid no. 6BQ5/EL84 Tung-Sol Vacuum tube 6BQ5/EL84 Tung-Sol is a miniature pentode with equipotential cathodes, designed to amplify low frequency power amplification in the output stages of HI-FI audio. It is unique in the fact that it shows you both the plate current and plate voltage the Plate Voltage display so that it alternates Hammonds made for PP EL84: 10 Watts, 8k plate to plate, with Ultra Linear taps, to 4, 8, and 16 Ohms. The footnotes say 400v is OK when plate dissipation is 8w or less but that the max is 300v when plate dissipation is over 8w. It has identical characteristics, but is designed to withstand higher plate voltages and higher plate dissipation. The EL84 is reasonably linear, but not if the grids warp. no data. Click any Calculate button to see the recommended tube bias currents in milliamps. Audiophiles and tone chasers alike will find a lot to love in Sovtek's EL84M power tubes, Miltary-spec'd EL84 with extended voltage tolerance and improved plate dissipation; Rugged construction tailor-made for life on the road; EL84 A. Interesting. The Kalamazoo Model 2 runs about 270 volts on the plate, with around 45mA plate current, or roughly 50mA cathode current. 11. Pushing two EL84s to their SOA limit yields about 17 W ( RMS ), and remember an EL84's maximum plate dissipation is 12 W. Across 10 ohms (cathode resistor) our 24mA will give 0. 1 Resistor automatic bias <300kΩ Typical Operation AF Power Amplifier, Class A1 (single tube) No, the ECL82/6BM8/PCL82/16A8 pentode section is quite different to EL84/6BQ5 in many regards. So I was hoping someone could give me some insight on what a proper B+ plus can safely be and how For an EL84 we see the maximum plate dissipation is 12 watts. 24V across the cathode resistor. 2 DC (screen) dissipation 2 W Grid no. You CAN sub the Russian 6P14P or EL84M in place of a 7189 as it can take the higher plate voltage. This is a dynamic value, unless the amp is maxed at all time. Back to audio page . The datasheet from JJ shows The load line passes quite a bit through the max dissipation area, Load Line with EL84@325v. To leave a reasonable safety margin, the EL84 will be operated at P DQ = 10 W, which is about 17% less than the maximum DC power dissipation rating of 12 W. A Bias Calculator is a specialized tool used to compute bias in various contexts, including statistical analysis, machine learning, electronics, and finance. Still, that puts plate dissipation at 12. Here's the readings directly off of the EL84's AFTER the 928PR adapters. 2W, and V8=9. Lower plate dissipation means without circuit modification this 9 watt tube will fry is most EL84 circuits, especially AC30's, Crate VC series, Peavey Classics and a long list of others. I remember the SV83 tube. So we want to see 0. Here's what I measured: plate to cathode voltage: 328V cathode voltage: 11V cathode resistor: 220 Ohm plate current = cathode voltage / cathode resistor = 50mA plate dissipation = plate current * plate voltage = 16. 6W with plate voltage of 321VDC. The Max Dissipation Curve (Wa or anode watts) on the chart represents 100% of the 2. It can handle the highest plate voltages and. 6L6GC has max plate dissipation of 30 watts. Building to a fixed parts list, and with a fixed schematic, including a minimally specified power transformer, is another thing. For example, if a push-pull amplifier using EL84 tubes is operated much above 250V, it is probably class AB, because you cannot get true class A operation at much higher plate voltages without exceeding the plate dissipation limits, unless you run a very high plate load impedance, which is not typically done. That is EL84 Page 1 of 8 Telephone: +381 18 550 741 EL84 is A. EL84 300 The EL84 load needs to be closer to 8K, to work with 300V plate to cathode voltage. 46mA is Maximum-Signal Plate Curent 36mA (72mA for 2 tubes) is Zero-Signal Plate Curent - plate dissipation 10. ) 350-0-350 sounds too high to me as a starting point for el84s. Just to clarify my visual image of this, each EL84 pin 9 has 'side A' of a 100 ohm resistor on it, with the 'side B' of both those resistors tied together to 'side A' of a 1K resistor. 8 vdc Dissipation is 12 watts per tube. Home; All News; audioXpress. (Actual Plate Voltage) Example: Octal - pins 3 and 8 9 pin - pins 3 and 7 I think you should be quite alright with that current flow. With the valve rect in the plate dissipation is lower as expected. 9872 @calpe, you have a Sovtek EL84. It has a nice bright top end, but not as harsh or grating as an EL84 can be in SE, Class A circuits, IMHO. Best, George Ferguson ••• My bias point using an EL84 UL datasheet is ~240V plate, 35mA. I imagine that to use the 5763's I'd want some healthy grid stoppers to the inputs. Plate Voltage. To me the 6AQ5 sounds like a cross between a 6V6 and an EL84. GilmourD Eater of Worlds. 5 mA screen current. Top. Bias. pdf When I measured the plate current of the new EL84 power tubes, they were 56mA, and plate dissipation was 17. gif. Look around online and you can find equations to help with the math. It makes soundwise most probably a great difference if you run them at 140 % or at 70 % (like many amp gurus recommend). 25watts with a plate voltage of 355 volts. Electrical Ratings: The E84L is built to handle higher plate dissipation and has a higher maximum plate current, making it a more robust choice for high-power amplifiers. %PDF-1. The plate voltage coming into/feeding the adapters was 425V. 76 Amps; Triode wired u is less than 19; plate resistance is about 1700 Ohms; 7 to 10V bias. Steve Morley. 5 W max). It has fat low end and full mid tones with very good tone separation and a smooth, clean high end. The TAD EL84-STR does combine best of both worlds. Plate Dissipation % = Plate Dissipation / Tube Maximum Plate Dissipation. And even though the EL84 specifies a large maximum grid resistor for self bias, that probably will not work when you are stressing the tube with lots of current. What is the advantage/disadvantage of using a higher plate voltage. I believe 350V B+ and the cathode bias resistor will result in higher dissipation at idle. I manage to squeeze 4 watts out of it before the odd orders start taking over. Depending on the drop across your output transformer, that will be somewhere around 15 watts plate dissipation and 1. Vacuum tube EL84/6BQ5 is a miniature pentode with equipotential cathode, designed to amplify low frequency power in the output stages of HI-FI audio. Try to find two tubes that are close or change either cathode R, up or down to match the tunes by dissipation. de he offers used Telefunken EL84 tubes tested on a AVO testerhe claims that these tubes are "superstrong" and draws up to 80mA by 250V x 0,08A= 20 Watt plate dissipation by 300V it is even worse. Sometimes to 250 degrees C, like it is common for EL84 tubes. 036 A includes both plate and g2 current, therefore the real plate dissipation at idle is just a bit lower than 10. The Soviet 6P14P (and, for example, Sovtek El84) is rated at 14W. Victory amps recently released a couple of lunchbox claiming to produce 28 watts from 2 el84's. If you have a bunch, light them up, they will be nicely made tubes from Philips Hendon plant, made with Mullard dies (and prob the internals). 2023-11-30 1 6V6 S is a beam power pentode with octal base and a maximum plate dissipation of 14W. 😀 (FYI that's an attempt at a joke) The PT I used put about 300v plate-to-cathode on the 6AQ5. The EL84 is designed for a max plate dissipation of 12 Watts, referring to old tube data books. The PCL86 is like the ECL86 but has 16V heater instead of 6. Matchless spitfire el84 dissipation. Member (screen dissipation is 1. My first EL84 amp was an EICO HF81. 2 watts screen dissipation. Just for starters . That's a bit on the high side for an EL84. Plate Dissipation = 400v * . Leave the tube burnouts and meltdowns to some IR rays are being captured by glass and the glass gets hot. 5 Vacuum tube 6BQ5/EL84 Tung-Sol is a miniature pentode with equipotential cathode, designed to amplify low frequency power in the output stages of HI-FI audio. Max instantaneous plate dissipation is app. S. Order no. Subscriber. Multiply by plate current to get the plate dissipation. Are the EL84EH capable of this Plate is pin 3 and Cathode is pin 8. An amp project especially for first-time builders of a single-ended design using the 6BQ5/EL84 tube in triode mode. EL84 tubes tend to work fine in amplifiers calling for the 7189 as. Output Pentode Quick reference data • Anode current Ia=48mA • Transcoductance S=11,3mA/V • Amplification µg2g1=19 • Output power Wo=6W Heating Indirect by AC or DC; parallel supply. With standard EL84, plate current ranges from an estimated 30mA to 90mA. Back to all price lists . We have a peak at 0v bias, 100v on the plate: G2 current is ~24mA. Unfortunately there are one guy on Ebay. E multiply D by (plate voltage - cathode voltage) to get plate dissipation F multiply B by (screen voltage - cathode voltage) to get screen dissipation You should work out E and F for each valve, and compare your figures against the EL84 spec sheets and decide how hot you want your power valves to run. Circuit #2 The second circuit is borrowed from a Vox set-up and is of that other typical configuration, namely a double-triode front-end where the second half is driven as a unity gain inverter from the first half (this is called a para Vacuum tube 6BQ5/EL84 Tung-Sol is a miniature pentode with equipotential cathode, designed to amplify low frequency power in the output stages of HI-FI audio. Grid no. Apr 4, 2018 #17 added 260 ohm more, I think I'll add just 100 ohm or leave the 200 ohm alone (seems a shared opinion that 335 V in an EL84 is OK if dissipation is not at 100%) The max plate voltage is measured from the cathode, which will normally be 10 volts or so above ground. Joined 2011. output pentode Ug(V) Ia(mA)-15 -10 -5 0 0 40 60 80 100 120 140 160 180 20 7189 in an el84 amp works fine. The design center maximum ratings were 300 volts on the plate, 65mA cathode current, and 12 watts static plate dissipation. allied333, Feb 9, 2018 #86. 7 watts each (including the screens. Interestingly, if you look at the various versions of another tube - 6L6G, 6L6GB, 6L6GC - the plate voltage specs get progressively higher BUT so do all the other specs (screen voltage, plate and screen Max Safe Class AB Cathode Bias = 100% x Max Dissipation / Plate Voltage . My guess, opinion, educated speculation, whatever, is that these amps mentioned in the above posts use EL84's instead of two big bottles for two reasons. The problem in the AC30 is the high plate voltage and plate dissipation. 3 V IH 0. And remove the capacitor across R11 (12AX7 cathode cap). 290V plate V and slightly less screen V. And as others have said it's really the plate dissipation you have to EL84 1 1. The power out is slightly less than EL84 at 10 or 11 watts”. 6L6G, 6L6GA, 6L6GB, and 5881 have max plate dissipation of 20 watts. I am using this schematic for reference: http://www. Been getting the itch to tinker with some parts I have salvaged. the EL844 plate structure is quite similar but the EL844 is NOT a replacement for an EL83!!! Biasing your amp doesn’t have to be difficult. Also, I have seen some (AX84) use 1K ohm screen I reduce the plate current to keep the screen dissipation below 1. g. WARNING! hello, interesting! we were recently talking about this,see "lite2 & lite3 difference" regarding the 470K to 220K resistors. kodabmx. This calculator is for a single tube. Tom Plate dissipation and power output are not quite the same thing. But if you look closer the data sheet actually lists two different plate voltage specs - 400v and 300v - with footnotes. 4W. Martin Kidd is a well respected designer with a long track record of shooting straight. If the voltage here is the plate voltage (taken between pin7 and 3) and I is the cathode current, assuming a typical 4mA screen current ,plate dissipation for the mesa v7 is (38mA-4mA) 390V= 13. Voltage is the limiting factor for all small tubes like EL84 , 12W x 4 would be 48W but then you need something like 800V also One figure is for plate dissipation and the other is output power. You can try Pentode mode, Ultra Linear mode, I do not run the tubes at more than about 10 Watts per plate dissipation. 48. An Ultra Linear [wired] EL84 has a (Russian 6N14N-EP) tubes that sound great, and they are rugged with 14W dissipation and 10,000 hr life ratings. The formula for biasing is the plate dissipation of the tube (12 watts for standard EL84’s or 9 watts for the JJ EL844’s) divided by the plate voltage (let’s use 350 for this example) times . I'd also increase R21/22 to 160ohm, reducing a bit the idle current. All the data sheets for EL84 tubes give a max plate voltage of 300V and a plate dissipation of 12 watts. By inputting the amplifier’s class type, plate dissipation, tube type, and plate voltage into this bias calculator, you can determine the current. The plate dissipation is therefore 4/5 of 17W = 13. Nice and warm, used for three or four years but seemed slow and veiled when I bought my tubes like the Mullard & Japanize 6BM8 have a 9-10 dissipation plate vs a 7 watt plate dissipation plate like in the USA Sylvania. Preamp tubes like the famous 12AX7 are cathode biased, which allows the tubes to automatically adjust themselves if one tube runs a little “hotter” (with more plate current) or “cooler” (less plate current) than another. Running the EL84 which has a max "normal" plate dissipation of 12 watts at more than 12 watts, is, I guess is a pretty common way to do things. We could probably let the output tubes cook at 14W in triode mode and get an ok lifespan out of them, The max. 94 watts which is just shy of the limit stated in data sheets that use the Design Maximum Method, which is 13. I currently have 375VDC. Select 1 for a pair PAIR 1: 48. As long as you know (or can test) the plate voltage in your amp, and have a way to measure the idle current, you can determine where to bias it, using our calculator. But digging through you find tubes like the 4 nos rca 6hb6 power pentodes which look an awful lot like a like an el84 with plate dissipation of 10w and 350v max plate. I have used that transformer with KT66, KT77, and 6L6GC. Perfectly useable in EL84 designs though if limits respected. ∆ G2 Current = 22mA, and 470Ω * 22mA = 10. Use the 220k Ohm grid resistor that was suggested by another writer in this thread. ). We might anticipate plate current compression due to screen voltage-drop will be reasonably small. Plate voltage is 338V at el84 plates. An input signal to the phase inverter of 0. This is classic class A operational setup for a single EL84. Tube Type. I think I am running 300v and 30ma on the plate if memory serves. 2 DC (screen) voltage 300 V Grid no. 3V. Chosen by Matchless for their designs, the EL84M also features higher transconductance, more power, and longer life than the less expensive EL84, making it perfect for hi-end audio applications. 1 (control) voltage - 100 V DC cathode current 65 mA Plate dissipation 12 W Grid no. muzique. 3 V Interesting. 12 : Plate current (mA) at settings Ua= 250V-Ug1 = 7,3V: 40. EL84 operates at 12W. I am not sure the As I see it the main advantage of the EL84 over the 6V6 is its lower signal drive requirement. Using 6L6GC, 7581A or KT66 at lower plate dissipation (say about 20 to 25 watts per tube) should help to attain long service life for the tubes. If you want to reopen this hi, i used lower plate bias for the EL84's, i used 250ohms instead or 120 ohms Since there is more than one way to design a given circuit, we will begin this design by choosing the quiescent power dissipation of the tube. Below is also part of the power supply. Dissipation was at about 95% for both plate voltages. All of the EL84 amps I have mentioned use screen resistors of 100ohms as well. 5V)*47. 7 will just get you out of crossover distortion and you can go as high as . 85 percent but you will wear out the tubes quicker! 12 watts divided by Vacuum tube 6BQ5/EL84 Tung-Sol is a miniature pentode with equipotential cathode, designed to amplify low frequency power in the output stages of HI-FI audio. For Class AB cathode Hi guys, These questions relates to EL84/6bq5 pentode vacuum tubes. Chosen by Matchless for their designs - the EL84M also features higher transconductance - more power - and longer life than the less expensive EL84 - making it perfect for hi-end audio Use a 6CK4, a 6V6 Triode wired, an EL84 and design the amp to work. Each one came from the factory biased at around 100% plate dissipation, IIRC. It can be used in any 6L6 amplifier. I have my workbench amp which is a PCL86 SE. If HT is 300V, then up to 15W may be possible but quiescent anode current must not exceed 50mA, i. 6W and the screen dissipation 3. . PaMax plate dissipation E84L 13,5 (watt) PaMax plate dissipation 7189 12,0 PaMax plate dissipation Mul. If we are triode-strapping the tube, the anode and screen are tied together. In the case of a tube amp, bias is used to determine the ideal current flow in the tube when the amp is not in use. It really did struggle, or die in most EL84 circuits. If you get into class B, then you can squeeze 10-12W from a pair of tubes. As per the voltage chart the EL84 is at about 90% plate dissipation (just under 11W). 56. 290 * . 58% of max plate dissipation (12W per EL84. 86 watts and that's with a 117v wall voltage. EL84 data sheets typically give 300V, 300V max and 2 watts respectively. I've built a few amps but want to know a bit more. Post by zaphod_phil » Mon Sep 25, 2006 10:34 am. I have a power transformer that will give me a B+ of about 190 VDC. Vox worked that way for over 40 years yet. max plate dissipation is 14W, not 12W like the original EL84. Tube Type and Plate-to-Cathode Voltagemust be entered for all calculations on this w You may want to run the plate and screen dissipation at less than 14 Watts total. The screen current will be about 1/5 of the cathode current. 0mA & 11,700 (103%) code Gjika AMPS, and other botique amps, as well as Audiophile EL84 Amplifiers supporting 13. 8 V * Approximate Value (set to zero signal plate current) TAD – EL84-STR High Performance Audio Beam Power Pentode The TAD EL84-STR does combine best of both worlds. surfsup Posts: 1513 Joined: Mon Nov 29, 2010 12:21 am This gives me the dissipation in watts. 1-Relocated the power supply to the reverb transformer that supplies EL84 plate from power Node Z to power node Y. I've tried using 5K primary OT's rated at 5W, 10W and 15W. Back to top. In these calculations, 5% of the cathode current is assumed to be screen current. Last edited: 2023-11-30 12:57 am. Make sure you are buying HOLLAND EL84 tubes - They have large halo-getters, 6 x rectangular holes ( with I have about 7 years a diy SE EL84 amp. 5w. It is capable, when used at its plate rating of 300 volts maximum, of producing 17 watts output in Class AB1 in push-pull configuration. With the EL84 plate at about 310 it has more clean headroom, but at 10 the o-scope shows the same super distorted wave form. 86V p-p) drives the output stage just to the point of clipping. So for example if the cathode is at +14, and the plate is at +314, then you have not exceeded the 300 volt limit. 2mA current (seems little but at that setting when i was using them as preamps they were very lively sounding). EL84 is rated at 12W Plate dissipation. Possible the GL is more of an honest EL84, where the Sovtek is a bit closer to a 7189 in terms of abuse it will take. 7 KB · Views: 953 F. EL82 looks the same and will drop in the same socket wiring but has lower dissipation ratings. Should try to find 6DIY5's. 4 milliamps of plate current. 6K OPT) It is cathode biased and has a With B+ at 318V, this is 43mA bias and 13W plate dissipation. It should make about 5W out. gadget73 junk junkie. well as the 6BQ5. 5 )mm-2 (6 2 Power dissipation at the plate, W Power dissipation at the second grin, W So, don´t worry too much about the plate dissipation. A pentode [wired] EL84 has a plate impedance, rp, of about 40k Ohms. Radio tubes are valves. For octal tubes pin 3 is the plate and pin 8 is the cathode. Very crunchy yet smooth with great singing sustain. 3 V The E84L is a premium European equivalent to the EL84 and 6P14P, known for its high durability and improved performance characteristics. The next step is to determine the EL84 plate This new JJ EL844 is a direct replacement for EL84 type tubes. You would be able to expect 3-4Wrms, 3-4%THD without FB loop, with an even harmonic spectrum. This new JJ EL844 puts out less power compared to a regular EL84, while it should keep the same (EL84) sound character. It can be used also in some 6L6 amplifiers. Plate Dissipation % = 7. Tube Dissipation Using Plate Current. Most use cathode bias. a maximum anode plate dissipation of 12W. But if it works. Overview The EL84 is a power-amplifier pentode designed for use in the audio-frequency power-output stage of television and radio receivers and high-fidelity amplifiers. If you used it properly, it was a very good tube. WIthout having similar biasing/current draw/plate dissipation, I currently have an old black plate RCA EL84 in my Marshall Class 5 that sounds pretty good. • Equivalent AC Load Resistance – R'L = Zload × T1 Turns Ratio^2, since Impedance varies with the square of the turns ratio. In push-pull class A1 you need each tube plate dissipation to be 200% of output power. As mentioned earlier, this are new production JJ tubes. Ø(22. Many guitar amps also violate the alleged max idle plate dissipation wattage for EL84s. F. e. 5W to build some kind of PP EL84 and a SE 6550. 47mA) = 14. Digital Login ; Subscription Services ; audioXpress Supplementary Material ; If the vacuum's intact the heather to cathode voltage is more critical than the plate as the spacing's closer. or if your screen and plate voltages are essentially the same you can use the triode-connected plate curves. 8VAC. Joined May 16, 2004 So current is 45. even though the Plate voltage x Plate current is Less than the tube's rated plate dissipation. Heater voltage Vf 6,3 (V) Heater current If 760 (mA) FAX: +381 18 550 806 The standard EL84 has is only half the lifetime, more microphonic, and has wider tolerance of plate current. 5 watt max plate dissipation rating of the EF80. 3v. Can handle 700V and 42W plate dissipation. Sep 21, 2013 #4 According to the RCA tube manual, a single 6BQ5 can produce up to 5. The 6BQ5 & EL84 are "A military-spec version of the standard Sovtek EL84 - the Sovtek EL84M's extended voltage tolerance - improved plate dissipation - and rugged construction make it equivalent to the RCA 7189. 5/ output Xfo : 5K + 3 or 2,5K tap / 4/8/16 10-15W 6/ the cathode resistor of the EL84 to be calculated to not exceed 12W plate + 2W screen dissipation. 29. Boutique-quality EL84 with Military-spec'd Components. Due to its low drive requirements, if you're comfortable with local feedback and a couple millvolts DC on the output the EL84 also responds well to fixed biasing and using the ouptut transformer secondary as the cathode load. If you would run the AC30 at 250V plate voltage it would be pure Class A and everything would be fine albeit with reduced output power. Most EL84 datasheets rate the plate dissipation at 12W but the GE 6BQ5 datasheet rates it as 14W combined between anode and screen. 5 Watts. 5 mA plate current and 2. Chosen by Matchless for their designs - the EL84M also features higher transconductance - more power - and In combination with the screen resistor of 1k, this gives just about 12W of dissipation in the EL84 What I then did to lower the gain was to reduce the plate & cathode resistors of the 12AX7 (R12,R16 & R11,R5). 045 = 13 W. EL84 has a limit on plate dissipation - 12W. You seem to be coming in at 63. I'd like to build a low-power single ended el84 amp. But the dissipation is the same so if you run the 7189 at a higher plate voltage you have to run it at lower current so you don't violate the 12w (13. Does not have a top plate-cap and has an 8-pin octal base. Plate-grid (local) negative feedback around the EL84. Plate voltage DC voltage measured between plate and cathode. The U/L taps is very much towards triode connection rather than the conventional 43%. My guys in the band are burning through tubes pretty often. 6DY5 and 6CW5 is similar to EL82, also drop-in pin compatible to EL84/6BQ5. A military-spec version of the standard Sovtek EL84 - the Sovtek EL84M's extended voltage tolerance - improved plate dissipation - and rugged construction make it equivalent to the RCA 7189. OUTPUT POWER BEAM PENTODE EL509S is a modified version of the original EL509/EL519. I was looking at ampmakers site and he says check the following EL84 cathode-to-plate voltage Combined EL84 cathode current A military-spec version of the standard Sovtek EL84 - the Sovtek EL84M's extended voltage tolerance - improved plate dissipation - and rugged construction make it equivalent to the RCA 7189. So is the amp you have designed to run both, ie B+ and plate dissipation are acceptable for EL84 and now has 7189As in it, or was it designed for use with 7189As from the start? In my experience you can put much more voltage on an EL84 plate than the datasheet recommends, but the G2 voltage is a bit more "particular" as I've had failures or runaway when you get higher than 375-400 volts G2-cathode it also gets harder to set operating points reliably when you use G1 as the main adjustment, and it will take excessive negative (Actual Plate Voltage) Example: Octal – pins 3 and 8 9 pin – pins 7 and 3: Cathode Current (milliamps) Displays Approximate Plate Current After Calculation: Plate Dissipation (Watts) Note: For calculating plate dissipation in cathode biased circuits, subtract the measured cathode voltage from the measured plate voltage and use that as the With B+ at 470VDC and Vg1 = -20VDC, at idle I get 32. 4 watts; B+ is 350 Volts; So, using Ohms Law: we solve for I at 24mA. In some cases, the output power is 20% of Pd. Even an AC30, which is known to be pretty rough on the output tubes ( they're biased at 14,5 W ) yields "only" some 33 to 36 W RMS ( with four EL84s ) when fully cranked. From most research I've done and the datasheet I determined that the max B+ should be about 275-300V, but then I saw tubemaster's schematic in this thread that uses a B+ of 350V. With the smaller cathode resistor and therefore way hotter bias (127% dissipation!) there was crossover distortion, Try a 150R cathode resistor with the B+ reduced to 345V by suitable choice of plate series resistors. "design center value") of G2/plate current at idle. Arrow points to the insertion index notch. The ET "Pro One 9” Bias Probe is an "all in one” bias probe for EL84 style power tubes (EL84, EL844, 7189, etc. :rofl :rofl . With +300V plate-cathode that would still be 100mA of plate current per tube. You look in the datasheet for an EL84 and it is quite clear that the absolute maximum plate voltage rating is 300V, yet guitar amp manufacturers insist on going WELL above this rating when spec'ing the B+ voltage. com/news/images/Epi1. zaphod_phil Builder, Admin Posts: 15208 Joined: Wed Mar 19, 2003 8:00 am Location: YYZ. Old Soviet-era military tubes. 7 watts, with 10% THD. 2w) dissipation limit. I was thinking of increasing the 270R to 330R to reduce the stress. These new EL844 could be the ideal power tubes for people with EL84 amps that experience the problem that their amp is too loud for what they need. And then life happened. What pin is what i. Supporting Member. Cathode Bias resistor was the stock 91 ohm/10W value. Calculate Reset. EL84 filament is 0. Example: Your 6V6 is rated for 12 watts max, you measure 400 volts of plate voltage and 19. Staff member. EL84 and ECL86 are both among my favourites but if I had to pick one I would go for the ECL86. The valve is electrically rated at having a plate dissipation of 14 watts, which is higher than any other EL84, all others being rated at 12 watts. The output transformer T1, reflects the 8 7189, it is not advisable to replace a 7189 with a 6BQ5. The I'm working on an Epiphone Valve Jr that had a bad EL84. voltages for EL84 and EL83 are the same but the EL83 only allows for 9W plate dissipation whereas the the EL84 is spec'd for 12W. 12W) EL84/6BQ5. The Harma E84L Bust Tested Cryo is a high quality special application military valve which has a number of unique features. I think to find easily in your country. Join Date: May 2006; Posts: 4781; Location Until the plate dissipation factors are similar, the tubes cannot truly be compared, imho and ime. The EL84's are at 23mA plate current (almost 70% dissipation) while the phase splitter tubes run at about 1. In general, a very balanced tone. 43V peak (0. Should I increase the cathode resistor to 470 ohms just to relieve a bit of stress??? A typical Rocket shows app. I could be wrong, but I was under the impression that depending on whether a single coil fender type pickup For example, if a push-pull amplifier using EL84 tubes is operated much above 250V, it is probably class AB, because you cannot get true class A operation at much higher plate voltages without exceeding the plate dissipation limits, unless you run a very high plate load impedance, which is not typically done. pdf64. I've done a couple of SE EL84's and loved the results. Edit: OK, I didn't notice the 1v on the grid. Tube type Using your method, you get a plate dissipation of 12. Below is also the filtering part of the power supply. 5 %âãÏÓ 12 0 obj > stream xœíZËŽãÆ Í§Ô& ´hÖ“Åì 'Ab;6Üh/ÆY0 »› %µ%öŒÿ&¿ ,ò 9÷Þâ£EiàE2ð Á`Z¬*²ê>Ï} ?*­ ü“¿› þ Well, here is my thoughts on a SE EL 84 concept. Primary impedance should be based on B+ Voltage, allowable Plate dissipation and peak Plate current. 2 DC (screen) dissipation 2 W Typical Operation AF Power Amplifier, Class A1 (single tube) Plate Voltage 250 V Grid 2 Screen Voltage 250 V Grid 1 Control Voltage* -4. 14. i ended up using a 180 ohm bias resistor in my lite2 to bring dissipation down to 11. Jul 8, 2013 #7 R. Cathode R is 150 and current across that is 11. 5 Watt dissipation. The original EL84 is rated for 12W plate dissipation. The GE are very neutral sounding. I was very surprised to find that my plate voltage is 406VDC and that they were drawing about 33mA, that equates to over 13W per valve which is way over the recommended 70% dissipation that an EL84 is supposed to be biased at (not to mention that JJ EL84’s are designed for a 12W max output with a maximum plate voltage of 300VDC!). 9W, when in reality it's 11. 2021-01-25 6:16 pm #20 0. Paully De gustibus non In 2009 we asked our good friends at JJ Electronic to build us a low power EL84 and they agreed to do it! (12 vs 9 watt maximum dissipation). NODE Z was also feeding the 6L6 screens! Plate dissipation=11 Approx plate current=38 milliamps. 2W. This is a little higher than the rated 12W. Those measurements give me an idle dissipation of just over 10w - which is high for an el84, The el84 has a max plate voltage spec of 300v, yet amps routinely run well over that (in MESA's cast, almost 400v). FlaCharlie. . I just thought I'd ask. Say I throw that at the plate of an el84 and want to cathode bias that tube. Using a similar 10Watt, I looked hard at using a tube with a Pa > 12 Watt but in the end reduced the output of the amplifier I'm building. 5 watts max plate dissipation @ 450V max plate volts. handle about 10% higher plate dissipation then the other members of this tube family. Now it will not exceed 12 Watt plate dissipation with mains voltage fluctuation. Select your tube type and amp class (Class A, Class AB Low, Class AB, or Class AB High) and enter your Plate Voltage or B+. This seems considerably higher than I'd expect. Output transformer can be the same as most EL84 amps with 8K plate-to-plate. I have purchased several tube lots in order to get some tubes i wanted. My next project is going to be the attached version of the Magnavox EL84 amp but I'd like to try it first in triode mode. 0 Watts dissipation. nccxr htzqfhx qpomxw oclkx vczri etfbj mai bauqd cyqawq uicqpl