El84 plate dissipation. 7 watts each (including the screens.

El84 plate dissipation I see amps with 350 on the plates, or even 400v for some with EL84s. If you get into class B, then you can squeeze 10-12W from a pair of tubes. I've been looking around and noticed the Dynaco SCA35 uses 360 at the plates. 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. 3 V, when run at 230 V, switched to the 225 V position. Paully De gustibus non I've built an EL84 P-P in UL (7. 35 KB · Views: 237 46mA is Maximum-Signal Plate Curent 36mA (72mA for 2 tubes) is Zero-Signal Plate Curent - plate dissipation 10. An amp project especially for first-time builders of a single-ended design using the 6BQ5/EL84 tube in triode mode. I remember the SV83 tube. 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. FlaCharlie. EL84 tubes tend to work fine in amplifiers calling for the 7189 as. Many amp designers run these tubes at 400V to 430V on the plate. 5 )mm-2 (6 2 Power dissipation at the plate, W Power dissipation at the second grin, W gives just over 32 watts output with max plate dissipation slightly over 12 watts. 11. This is a little higher than the rated 12W. If your amp wasn't asking the most from a EL84 as set up, this could be a possible alternate. 😀 (FYI that's an attempt at a joke) The PT I used put about 300v plate-to-cathode on the 6AQ5. We might anticipate plate current compression due to screen voltage-drop will be reasonably small. 65 or 65% 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. After a 24 hour burn 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). 80-9. My band:- http e. 9W, from pin9 of V4 to pin9 of V5 then another 100R then to the 1k screen resistor on the turret board X2 because I have 4 el84's Is 1/4 watt resistor enough for this purpose? I got a 36w question regarding this. I recently got a couple of these and it seems for a single tube 10W is the max plate dissipation. The problem in the AC30 is the high plate voltage and plate dissipation. EL84 filament is 0. Idle dissipation should be closer to 9 watts/tube. The For an EL84 we see the maximum plate dissipation is 12 watts. Vacuum tube EL84 Mullard is a miniature pentode with equipotential cathode, designed to amplify low frequency power in the output stages of HI-FI audio. The 6P14P-ER tube is the longest rated that can be biased as an EL84. If you used it properly, it was a very good tube. 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 you really need to watch for is the plate dissipation. The dissipation is a factor of the voltage and the bias current. 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 . 3 V A lot of people seem to think 5K is the ideal impedance for a single ended output transformer primary. 2 Meg Ohms. 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). Normally in a fixed biased amp, 80% to 90% would result in the tubes running too hot when cranked. Right now I have this amp biased with 32ma cathode current so right about 12 watts. That's allows for >10% losses, eg OT, in a real implementation. PaMax plate dissipation E84L 13,5 (watt) PaMax plate dissipation 7189 12,0 PaMax plate dissipation Mul. In general, the EL84 output tubes would last several months of moderate use, and then crap out. The The TAD EL84-STR does combine best of both worlds. 3 V 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. I ended up with a low power "version" makes absolutely no sense, and is a very dangerous thing to be offering their current EL84 users. This as function of EL84 has a limit on plate dissipation - 12W. My bias point using an EL84 UL datasheet is ~240V plate, 35mA. Note that this build is using fixed bias and Toroidy EL84, 8k output transformers in UL connection, with regulated plate supply. 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. 0194a = 7. For Class AB cathode 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 . Unfortunately there are one guy on Ebay. F. png. A bit hokey but it works. (Actual Plate Voltage) Example: Octal - pins 3 and 8 9 pin - pins 3 and 7 EL84 is rated at 12W Plate dissipation. EL84. I think I am running 300v and 30ma on the plate if memory serves. 5V)*47. ). Miles's Taste Tests for 6BQ5 / EL84 Overview I got five new EL84/6BQ5 (the EL84 was the European designation; The design center maximum ratings were 300 volts on the plate, 65mA cathode current, and 12 watts static plate dissipation. (Va - Vk x kA cathode current) Do not exceed 14 watts. 7 KB · Views: 951 F. Ø(22. 14. So, using my 18 Watt as an example, They have a 50 Ohm resistor for 4x EL84. It is very similar to the 6L6 sound but with less power. That will allow biasing the tube to about 40ma, Also it will determine how much plate dissipation there is (without screen current). The key is to keep the idle current low with proper bias and use higher-than-normal load to keep The load line passes quite a bit through the max dissipation area, as well as terminating at -0v at the edge of max dissipation. 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. Plate dissipation (Watt) 11. Many guitar amps also violate the alleged max idle plate dissipation wattage for EL84s. That is, you can runn em with higher B+ but you've got to limit the current flow (higher value cathode resistor if cathode biased - more negative control grid bias voltage is fixed biased). even though the Plate voltage x Plate current is Less than the tube's rated plate dissipation. 3v. Best regards KJH Biasing your amp doesn’t have to be difficult. All the data sheets for EL84 tubes give a max plate voltage of 300V and a plate dissipation of 12 watts. 5 watts max plate dissipation @ 450V max plate volts. 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. The 7189 has an uprated max plate voltage of 440V and screen 330V. 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. And remove the capacitor across R11 (12AX7 cathode cap). 25watts with a plate voltage of 355 volts. 76 A Maximum Ratings Plate Voltage 500 V Plate Dissipation 12 W Grid #2 Voltage 300 V Grid #2 Dissipation 2 W Cathodic Current 65 mA Grid #1 Hi guys, These questions relates to EL84/6bq5 pentode vacuum tubes. ) 350-0-350 sounds too high to me as a starting point for el84s. I'd also increase R21/22 to 160ohm, reducing a bit the idle current. Same deal in some old small guitar amps. This amp is running 1. Joined 2020. Plate-grid (local) negative feedback around the EL84. 6DY5 and 6CW5 is similar to EL82, also drop-in pin compatible to EL84/6BQ5. 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. 2010-10 On some schematics (namely Orange's "Tiny Terror" and "Dark Terror") the plate voltages for EL84 power tubes are above 300V (like 325 or 314), The actual limiting factor of the tube tube is the plate dissipation rather than the specific voltage. F. The Kalamazoo Model 2 runs about 270 volts on the plate, with around 45mA plate current, The EL84's are at 23mA plate current (almost 70% dissipation) watts out of a pair of russian EL84 and that was the recipe, high plate voltage, low-ish screen voltage to prevent burning, moderate plate current leaving room for more swing. Interesting. 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. This is a dynamic value, unless the amp is maxed at all time. Use a 6CK4, a 6V6 Triode wired, an EL84 and design the amp to work. So why wouldn't one use a 12k or 15k OT to rotate that load line down to more reasonable levels? 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. I biased the 6AQ5 tube to 12W plate dissipation and have not had any redplating or other problems. Thread starter Cassiel; Start date 2006-12-09 4:18 pm; Status This old topic is closed. Across 10 ohms (cathode resistor) our 24mA will give 0. EL84 300 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. Use this calculator when you measure the actual plate current. "design center value") of G2/plate current at idle. Calculate Plate Dissipation Based On Plate Voltage And Cathode Current Readings. Back to audio page . That is what you should use to calculate plate dissipation Pa. D. Building to a fixed parts list, and with a fixed schematic, including a minimally specified power transformer, is another thing. Appreciate any help, al. I'm getting the impression that it's the guitar ampers that like the higher voltage. martin manning wrote:Subtract the cathode voltage from the plate voltage to get Va-k. Since they are 1k 5881 is a beam power pentode with a maximum plate dissipation of 23W in the classical short bulb. 2w) dissipation limit. 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. You have used the cathode current which is plate + screen current so you have calculated the plate + screen dissipation at 17W. And in the case of EL84 amps with a far too high B+ are single rail Boochie, you're off in the weeds. Output tubes were rattly well-used EH EL84's, and biased about 10% beyond their suggested 12W plate power limit. Back to all price lists . At 300 volts plate-cathode it's still at a comfortable ~10 watts plate dissipation and you'll get more power out of it. ReVintage_SE-EL84-Schadeode_EXPERIMENTAL. Plate voltage DC voltage measured between plate and cathode. The 6P14P-EV or ER is extremely rugged and quite close in performance to the 7189, and it even sounds good in most applications. The plate dissipation is therefore 4/5 of 17W = 13. 47mA) = 14. 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. If you can safely do that, measure the plate current of the EL84 with the amp in its current state. 7W (note that the EL84 is only rated at 12W max plate dissipation). • Quiescent Plate Dissipation – pdQ = (VPQ-Vk) × IpQ = 11. 5W Matchless spitfire el84 dissipation . Given that a vast majority of EL84 amps are running the tubes at the ragged edge, dropping plate dissipation capability by 25% seems like asking for trouble. 7-13. If we are triode-strapping the tube, the anode and screen are tied together. Leave the tube burnouts and meltdowns to some IR rays are being captured by glass and the glass gets hot. 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. You can try Pentode mode, Ultra Linear mode, I do not run the tubes at more than about 10 Watts per plate dissipation. For octal tubes pin 3 is the plate and pin 8 is the cathode. 6W and the screen dissipation 3. 24V. Screen current and dissipation drops too. According to my old ( 1967 ) Philips tube data book, 550 VDC are the maximum plate voltage ( design center values ) for EL84s, but, even if willing to operate at these extreme voltages ( which I dislike ) in order to gain some headroom, to stay within the tube's max plate dissipation ( 12W ) the biasing current should be set very cold, at some If you were to watch your plate current the type 6W6 should plug right in - this bottle has a higher plate voltage characteristic with slightly lower plate dissipation. I said above that do not exceed the EL84 anode power dissipation given in the catalog. Grid no. Staff member. Heater voltage Vf 6,3 (V) Heater current If 760 (mA) FAX: +381 18 550 806 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. 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? 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. The closest plate curves, but voltages and power in specs are limited due to the smaller size. I've built a few amps but want to know a bit more. It has a nice bright top end, but not as harsh or grating as an EL84 can be in SE, Class A circuits, IMHO. The power out is slightly less than EL84 at 10 or 11 watts”. The 7189 is the tube I Miltary-spec'd EL84 with extended voltage tolerance and improved plate dissipation; Rugged construction tailor-made for life on the road; Boutique-level performance in tube amps and hi-fi audio systems; provides exceptional clarity in any application; Not compatible with Bad Cat Model 2R or Black Cat; Marshall DSL201 and DSL401 The E84L is a premium European equivalent to the EL84 and 6P14P, known for its high durability and improved performance characteristics. EL84 screen max is 300V and 2. Came across this while searching for something. TAD EL84-STR is reported to be a tough tube too but only 12 Watt anode dissipation but rated at 420V on the plate. 6L6GC has max plate dissipation of 30 watts. Select 1 for a pair PAIR 1: 48. The U/L taps is very much towards triode connection rather than the conventional 43%. Power dissipation at the plate, W Power dissipation at the second grid, W fixed bias self - bias (at: filament voltage 6. I believe 350V B+ and the cathode bias resistor will result in higher dissipation at idle. ) It may be biased a little cold to some, Having the tube biased close to 100% of max dissipation will also help the tubes not to go into starved mode on transients - Plate Dissipation % = Plate Dissipation / Tube Maximum Plate Dissipation. The amplifier is idle-biased to say 80% or 90% of max dissipation, unlike a fixed biased amp that would be biased between 50% to 75% of max dissipation. EL84 and ECL86 are both among my favourites but if I had to pick one I would go for the ECL86. Please login or register. The PCL86 is like the ECL86 but has 16V heater instead of 6. 5Watt dissipation. (consider the max Va on the tube datasheet to establish it), on the datasheet give a look also to the max plate dissipation and compute a . Are the EL84EH capable of this Better to be aware of the dissipation each EL84 has. i ended up using a 180 ohm bias resistor in my lite2 to bring dissipation down to 11. The GE are very neutral sounding. 58% of max plate dissipation (12W per EL84. Cathode Bias resistor was the stock 91 ohm/10W value. Tube Type and Plate-to-Cathode Voltagemust be entered for all calculations on this we Tube Dissipation Using Plate Current. 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. Home; All News; audioXpress. 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. He's posting idle dissipation numbers calculated for the EL84 tubes, they have a 12-watt max plate dissipation. It was similar to the EL84, but the screen was only rated at 250V and 1. Now operating part time: Glassman Tube Ampsrepairs, rebuilds, restorations & modifications of tube equipment. 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 automatically between displaying Plate Voltage and real time calculated Plate Dissipation. R. The Soviet 6P14P (and, for example, Sovtek El84) is rated at 14W. So we If HT is 300V, then up to 15W may be possible but quiescent anode current must not exceed 50mA, i. I personally like my tubes biased at 60% or 70% of static dissipation and the hello, interesting! we were recently talking about this,see "lite2 & lite3 difference" regarding the 470K to 220K resistors. 4 watts; B+ is 350 Volts; So, using Ohms Law: we solve for I at 24mA. Matchless spitfire el84 dissipation. Member. Best, George Ferguson ••• The amp will have a B+ of 385 or so, and my cathode resistors are 182 ohms and half of a 100-ohm pot per PP pair. Hi can someone tell me how to check bias and dissipation etc on the el84's. With +300V plate-cathode that would still be 100mA of plate current per tube. We did choose the thickest glass option and most heasvy construction like the Russian EL84M and sonically most promising cathode Excess dissipation - caused by any combination of voltage and current - can cause a tube to wear out more quickly. The E84L that you speak of by Siemens is a good tube. To me the 6AQ5 sounds like a cross between a 6V6 and an EL84. The amp has still minor issues, like one channel a bit louder, and highs a bit tammed in one channel, but it 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 This might get your plate dissipation down to 11 watts, which is within spec. 0 Watts dissipation. Tom I then add the 100R resistors on the screens. The next step is to determine the EL84 plate The ET "Pro One 9” Bias Probe is an "all in one” bias probe for EL84 style power tubes (EL84, EL844, 7189, etc. Welcome To the Hoffman Amplifiers Forum December 21, 2024, 10:39:14 pm: Welcome, Guest. If you want to reopen this hi, i used lower plate bias for the EL84's, i used 250ohms instead or 120 ohms Hammonds made for PP EL84: 10 Watts, 8k plate to plate, with Ultra Linear taps, to 4, 8, and 16 Ohms. Perfectly useable in EL84 designs though if limits respected. Bias. Primary impedance should be based on B+ Voltage, allowable Plate dissipation and peak Plate current. The 7189A is an improved version of type 6BQ5/EL84. allied333, Feb 9, 2018 #86. Plate dissipation and power output are not quite the same thing. Dissipation was at about 95% for both plate voltages. Plate dissipation is low at 10 watts and screen dissipation is at 1W. Marshall-1974X-18W-Schematic. 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. no data. 7mA I read where people say you can really push these tubes. handle about 10% higher plate dissipation then the other members of this tube family. The datasheet from JJ shows I reduce the plate current to keep the screen dissipation below 1. This calculator is for a single tube. SY, I will have a look at your Red Light District amp. 2023-07-07 11:18 am #9 2023-07-07 11:18 am #9. Idle Plate Dissipation, Plate Current, & Mesa Color Code Chart project. 8W. But it isn't near the quality of a Mullard EL84 or 7189. Just for starters . 0mA & 11,700 (103%) code Gjika AMPS, and other botique amps, as well as Audiophile EL84 Amplifiers supporting 13. Our observation: We’ve compared these to all of the classic European EL84’s, I own several Blues Juniors. On a Sansui A-500 for example, an EL84 wouldn't work as wired from the factory because they chose to use the alternate connections. Cathode current - screen current = Plate current Plate voltage - cathode voltage = Plate to cathode voltage. A+! plate voltage and output range: 250 VDC and 8 watts max plate dissipation (AB1, push-pull). 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. What pin is what i. Anyone have any opinions? Things look good, as the only the EL84 plates and grid-2 see the raw B+ noise, In other words, both tubes are closer in true peak current delivery, but differ in maximum plate dissipation, 42W versus 13W for each 6AS7 triode (the 6AS7 is a twin-triode design), 4/ plate supply : 250-300VDC required. In push-pull class A1 you need each tube plate dissipation to be 200% of output power. Some amplifiers do push this and the closer they get to the 14 watts Plate is pin 3 and Cathode is pin 8. Russian 6P14P plate 250V, screen 250V. 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. I could be wrong, but I was under the impression that depending on whether a single coil fender type pickup The first and foremost is not to set the bias current so high as to exceed plate dissipation at any portion of the tubes operation, If you run an EL84 at 300V, for instance, the 12W plate dissipation limit requires you to bias the tube at a point where it will be in cutoff for a significant portion of the input cycle, If the amp is working then the sockets are wired to use standard EL84 Pin-outs. , the Musical Reference uses around 750V for the plates of the EL84. 3V. The plates look to have a different coating than anything else coming out of new sensor in EL84's and this, Very crunchy yet smooth with great singing sustain. Using your method, you get a plate dissipation of 12. Sometimes to 250 degrees C, like it is common for EL84 tubes. Chosen by Matchless for 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. Also I found several comments that 6P14P-EV's plate dissipation is 2W higher than EL84, which should also help with reliability. By coincidence I was working on a similar amp for a customer. 76 Amps; Triode wired u is less than 19; plate resistance is about 1700 Ohms; 7 to 10V bias. output pentode Ug(V) Ia(mA)-15 -10 -5 0 0 40 60 80 100 120 140 160 180 20 I ordered new J/J EL84 & EZ81 tubes, which came in today. We have a peak at 0v bias, 100v on the plate: G2 current is ~24mA. 5 Watts. I just thought I'd ask. The high plate voltage (within reason) won't make those tubes flinch, it's really the over dissipation of the screen and under-biasing that will kill them. 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. In these calculations, 5% of the cathode current is assumed to be screen current. 3 V IH 0. 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. Would I also want to put big screen resistors? I installed a new EL84 from JJ and decided to check the plate dissipation. 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. many EL84 amps use cathode biasing, Class A triode operation in stereos is about keeping power low to avoid going over plate dissipation limits - 200-250 volts on the plates for 5watts per tube, but providing plenty of current without sag to keep response at all frequencies flat and accurate. Using a similar 10Watt, Voltage is the limiting factor for all small tubes like EL84 , So 55W maximum plate dissipation happening at low power delivery means 27. Of course you have to bias the tube appropriately if you do this. But with more than 8 Watts plate dissipation (> 8 Watts), the 6P14P maximum plate volts is 300V. But that amp also has 400+ volts on the plates so the current production 7189, EL84M are needed. 85 percent but you will wear out the tubes quicker! 12 watts divided by EL84 Page 1 of 8 Telephone: +381 18 550 741 EL84 is A. • The output of the tone stack is fed to the EL84's grid via grid snubber resistor R6. 0368 Plate Dissapation=plate V-KV x plate current. 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. I was looking at ampmakers site and he says check the following EL84 cathode-to-plate voltage Combined EL84 cathode current The 6BQ5 is rated for 300V plate and 300V screen. Sep 21, 2013 #4 Those early European hi fi sets that sported a pair of EL84's running about 275V on the plates and sharing a common 130 ohm cathode resistor. 036 A includes both plate and g2 current, therefore the real plate dissipation at idle is just a bit lower than 10. 7 watts each (including the screens. Most use cathode bias. Max instantaneous plate dissipation is app. Plate Dissipation = 400v * . 7W. 2w per tube depending on the voltage drop of the bias resistor. 76w / 12w = . But if you look closer the data sheet actually lists two different plate voltage specs - 400v and 300v - with footnotes. We might idle with bias of -10v at 300v on the plate: G2 current is 2mA. Should I increase the cathode resistor to 470 ohms just to relieve a bit of 7189, it is not advisable to replace a 7189 with a 6BQ5. Click any Calculate button to see the recommended tube bias currents in milliamps. e plate voltage pin and which ones are screen resistors etc. I have used that transformer with KT66, KT77, and 6L6GC. 290 * . 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. 6P14P - 3000hr 6P14P-V - 1000hr A typical Rocket shows app. 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. Attachments. Example: Your 6V6 is rated for 12 watts max, you measure 400 volts of plate voltage and 19. 5w. DC voltage measured between plate and cathode. pdf When I measured the plate current of the new EL84 power tubes, they were 56mA, and plate dissipation was 17. 2. 2W. With the valve rect in the plate dissipation is lower as expected. 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. Filament voltage, V. I manage to squeeze 4 watts out of it before the odd orders start taking over. 56. say 90-95% of it EL82 looks the same and will drop in the same socket wiring but has lower dissipation ratings. It should make about 5W out. 5W per tube which is the max rating per tube WITH signal (25W without) for the EL34. Make sure you are buying HOLLAND EL84 tubes - They have large halo-getters, 6 x rectangular holes ( with Plate Current=KV/KR value-screen current. 2021-01-25 6:16 pm #20 What was scary with these GT adapters, was I measured a reduction of aprox. 5V at pin #3 on the 6BQ5. 04-. 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. • Quiescent Plate Current – ipQ = (Vk/R15) - iSceeen = 47mA, where iScreen is the screen current. Specifications Heater UH 6. E. Digital Login ; Subscription Services ; audioXpress Supplementary Material ; Errata With around 285V on the plate, I was looking for about 7. Although cathode biased amps are generally considered self biasing, it would not be a bad idea to take 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. You must enter Tube Type and Plate-to-Cathode Voltage above before calculating All the data sheets for EL84 tubes give a max plate voltage of 300V and a plate dissipation of 12 watts. 10V/250 Ohms=. Oct 23, 2023. SandAndGlass likes this. 045 = 13 W. 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. This gives me the dissipation in watts. Keep in mind that voltage and current could both be in spec, 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. Multiply by plate current to get the plate dissipation. No red-plating, now! Reactions: Pano. You would be able to expect 3-4Wrms, 3-4%THD without FB loop, with an even harmonic spectrum. Output transformer can be the same as most EL84 amps with 8K plate-to-plate. My screen voltage is very close to max rating in the Scott. Dissipation is 8. 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+. As per the voltage chart the EL84 is at about 90% plate dissipation (just under 11W). Adjustable cathode bias This is the trick used on the DIYtube EL84 amp. I measured the following with the old tubes and will repeat that with the JJs soon: Cathode 9. This results in about 47mA bias current per tube, making the plate dissipation around 13. 7 will just get you out of crossover distortion and you can go as high as . I have my workbench amp which is a PCL86 SE. 4 W plate dissipation and has got less power but distortion is lower nearly up max power, This results in a quiescent plate dissipation in the output tubes of (320V-10. Look around online The max. 50ma is the maximum recommended sustained plate dissipation for the EL84 in SE Pentode operation. 70% of 12 watts is 8. 6L6G, 6L6GA, 6L6GB, and 5881 have max plate dissipation of 20 watts. 5w+ into Red Plate territory. max plate dissipation is 14W, not 12W like the original EL84. chuck The very successful EL84 is the last development step from EL3 via EL41 to the final point of radio output pentodes. 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. 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). The schematic of my 1967 Harmony H415 idles at 299 (net) plate volts for around 12. ∆ G2 Current = 22mA, and 470Ω * 22mA = 10. Order no. 15v (53r) (12. The screens are also high: A pair of EL34s would handle those plate voltages just fine, give you about the same plate dissipation as two EL84s, and would require the same heater current. This is classic class A operational setup for a single EL84. 4W. kodabmx. 2W, and V8=9. Cathode R is 150 and current across that is 11. Plate voltage is 338V at el84 plates. The screen current will be about 1/5 of the cathode current. The same as for an EL84. If you run it in an EL84 output section, you risk thermal runaway if you don't lower the idle bias. 0368=13. 7mA At EL84's 12 Watts max plate dissipation and 300V, that is 40mA. The amp has got just 1 tube per channel for over 2W power (triode The original EL84 is rated for 12W plate dissipation. GilmourD Eater of Worlds. 86V p-p) drives the output stage just to the point of clipping. 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. 6K OPT) It is cathode biased and has a With B+ at 318V, this is 43mA bias and 13W plate dissipation. Finally used both old 130 ohm in series with the B+ , so plate voltage is now 308V, plate current 31mA, 330ohm screen resistors, 9. These are guidelines, not absolutes. By adjusting the value of the cathode resistor, you can control the power dissipated in the tube ('plate dissipation') The EL84 has been much abused in commercial service. 48. Not a Mojo kit, B+ settles around 330V. This seems considerably higher than I'd expect. deafen. 6 Watts It this is correct and an EL84 is not to exceed 12 watts--need to raise the cathod resistor some??? According to Weber Calculator, Dissapation is 14 and plate current is 38 My first EL84 amp was an EICO HF81. . Hoffman Amplifiers Tube Amp Forum, 18 Watt Marshall clone general question about EL84 max plate current . Extrapolating roughly from that, I was going to suggest a So, your amp appears to be drawing exactly the recommended maximum (i. Voltage is high, but bias current is low. It lists maximum plate dissipation at 14w vs 12w for the 6BQ5, 7189 etc. 9 = 9watts 9/350 = 25. It has identical characteristics, but is designed to withstand higher plate voltages and higher plate dissipation. 43V peak (0. The plate dissipation is then the idle current multiplied by the plate-to-cathode voltage, divided by two if there are two tubes sharing the cathode resistor. One seller on the web says the 6P14P-EV military version is a 7189. EL84 A. The EL84 is commonly associated with the British sound of Vox amps. 6W with plate voltage of 321VDC. 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. 290V plate V and slightly less screen V. 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. I was thinking of increasing the 270R to 330R to reduce the stress. -User Name Running the EL84 which has a max "normal" plate dissipation of 12 watts at more than 12 watts, is, The warmer biasing approach used in vintage Marshall 18W and many Vox amps is an interesting one. rmyauck. 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 EL84 = 6BQ5 PREMIUM HOLLAND EL84. 48v Heaters 6v Plate 316v Screen 309v Cathode bias resistor 8. 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 You seem to be coming in at 63. The first and foremost is not to set the bias current so high as to exceed plate dissipation at any portion of the tubes operation, If you run an EL84 at 300V, for instance, the 12W plate dissipation limit requires you to bias the tube at a point where it will be in cutoff for a significant portion of the input cycle, The standard EL84 has is only half the lifetime, more microphonic, and has wider tolerance of plate current. 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. Chosen by Matchless for their designs - the EL84M also features higher transconductance - more power - and Pushing two EL84s to their SOA limit yields about 17 W ( RMS ), and remember an EL84's maximum plate dissipation is 12 W. 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. Measure the voltage across the screen resistors to get the screen current Ig2. 29. EL84 Pd should then be down to about 12W. Try to find two tubes that are close or change either cathode R, up or down to match the tunes by dissipation. 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. GE EL84 are far superior and I have tested many EL84s. 0032=. I'm also figuring that a higher Vp means shorter tube life. 12W) EL84/6BQ5. 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. What else? 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. 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. 500V on the plates seems much more reasonable, 25 watts is nothing to sneeze at from two 6BQ5's. • The input impedance is equal to R10, or 2. 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. Mile High Effects; Oct 12, 2023; Tubes; Replies 2 Views 1K. 8 vdc Dissipation is 12 watts per tube. It's dissipation power was increased from 9 to 12 watts, giving an output power of 5. g. Keep plate dissipation well below the 11 watt maximum specified for the tube. So at 350v, do I run it at 90% like an EL84? 10 * 0. e. Joined 2009. It can handle the highest plate voltages and. well as the 6BQ5. But the main way of dissipation is IR rays that go through the 0. Well, here is my thoughts on a SE EL 84 concept. That matches what you get out of real life amplifiers made when that tube was widely used. EL84 operates at 12W. An input signal to the phase inverter of 0. Enter the Plate-to-Cathode Voltage which is the DC voltage measured between the plate and cathode tube socket pins. Joined 2011. The Max Dissipation Curve (Wa or anode watts) on the chart represents 100% of the 2. 3 V Whoops. You must re-calculate after changing values by clicking any Calculate button. Plate voltage 346 V, cathode voltage 10. Each one came from the factory biased at around 100% plate dissipation, IIRC. Tube Dissipation Using Plate Current. 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. I'm willing to bet MESA set it up closer to 6 watts/tube. Should try to find 6DIY5's. 7 watts, which was seldom utilized. That is The Sovtek EL84M's extended voltage tolerance, improved plate dissipation, and rugged construction make it equivalent to the RCA 7189. Tube type In 2009 we asked our good friends at JJ Electronic to build us a low power EL84 and these must be biased 25% lower than standard EL84's to compensate for the wattage drop (12 vs 9 watt maximum dissipation). S. Using google I found favourable reports of the Tung Sol 7189. Plate Dissipation % = 7. With standard EL84, plate current ranges from an estimated 30mA to 90mA. 5 Watt dissipation. At 6P14P's 14 Watts max plate dissipation and 300V, that is 46. Speaking for "Sound of EL84", we need volunteers to experiment and draw typical plate NOS tubes from philips not good from me,fast die in 100% anode dissipation ,my amp have very hot bias. Amp sounds great, crossover starts just at clipping. 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 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. As i can tell that was a clas AB2, Most EL84 datasheets rate the plate dissipation at 12W but the GE 6BQ5 datasheet rates it as 14W combined between anode and screen. a maximum anode plate dissipation of 12W. EL84 is rated at 12W Plate dissipation. 5 watt max plate dissipation rating of the EF80. The EL84 load needs to be closer to 8K, to work with 300V plate to cathode voltage. :rofl :rofl . 12 : Plate current (mA) at settings Ua= 250V-Ug1 = 7,3V: 40. 100V on the plates, but had 36mA on each EL84 measured by my 1 Ohm bias resistors in the amp. The Mesa amp runs its output tubes at high plate voltages for an EL84: 436V according to the schematic, a bit higher in practice. 9872 @calpe, you have a Sovtek EL84. Arrow points to the insertion index notch. EL84 12,0 VaMax plate voltage E84L 450 (volt) VaMax plate voltage 7189 400 VaMax plate voltage Mul. But if it works. It can be used in any 6L6 amplifier. 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. 160 ohm substituted for the 125 ohm Rk, new pair of JJ EL84, Pp now 11. JM2C. 76 watts of Plate Dissipation. 380V-10V=370V x . (Actual Plate Voltage) Example: Octal – pins 3 and 8 9 pin – pins 7 and 3: Plate dissipation per tube (Watts) Approximate plate current in each tube (in milliamps) Will calculate and display plate power dissipation and approximate plate current per tube. ) No, the ECL82/6BM8/PCL82/16A8 pentode section is quite different to EL84/6BQ5 in many regards. I imagine that to use the 5763's I'd want some healthy grid stoppers to the inputs. It's data is similar to the European E84L/7320. Max plate volts and watts: 300 V, 12 W; Max screen volts and watts: 300 V, 2 W; Another early 1950s creation from the Netherlands, the EL84 was probably designed for affordability, and it helped make hi-fi stereo systems more accessible to the masses. . 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. It really did struggle, or die in most EL84 circuits. 1 Watts That seems too high. We could probably As I see it the main advantage of the EL84 over the 6V6 is its lower signal drive requirement. 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. 4 milliamps of plate current. kif ccf jric gvvnogqa iqpvx ifh oswdzy yybzdugy etarmwqw awm