Best 6l6 bias adjustment chart amp Locate the bias adjustment points: Identify the bias adjustment points on the amplifier’s circuit board or by referring to the amplifier’s user manual or schematic diagram. Adjust the next knob once done I put the bias pots so I can adjust them from the top of the chassis. One of you kind fellows suggested that I use a 6L6 based amp for more power, which is better suited to bass. I'd like to be able to swap in 6L6/6CA7/EL34. Our top selling go-to 6L6GC tube is TungSol 6L6GC-STR. There are exceptions. Or worse, your amplifier! Need to bias a 6L6? Find the optimal 6L6 bias points here. Requires separate digital volt-ohmmeter capable of reading current. Most amps with two or more 6L6 or EL34 power tubes fall into this category. Happy New Year from Mexico, Patricio Hello, Patricio. Often it is a switch that can select bias for EL34 tubes, or 6L6 tubes depending which is installed. smcgov New member. Biasing was easy and well within the range of the standard bias adjustment circuit in the test amp. Joined Oct 25, 2008 You have to mod the amp to add a bias adjustment to use non-Mesa tubes? Stephen What exactly is Bias? The best analogy of bias adjustment that we can think of goes back to older cars that had carburetors. Nice little prize you picked up at the pawnshop. Just remember the plate load impedance of a 6L6 is lower than that of a 6V6 so you'll be pushing the 6L6 a bit, and the heater currents on a 6L6 are twice that of a 6V6 so you might This website uses cookies to ensure that you get the best experience. Ended up taking the amp to a tech and after a scope check and bias down to the 73Mv range. the amp sounds best to me. – you should find this on top of the amplifier. 6L6 tubes are beam-power tetrodes, while EL34 tubes are What exactly is Bias? The best analogy of bias adjustment that we can think of goes back to older cars that had carburetors. Thanks for writing such a cool column. These amps were 40 watts, fixed bias with a bias adjustment pot, and the tubes were 4 x 7025, 2 x 12AX7, 2 x 5881 with a solidstate rectifier. It had a metal envelope which was popular at that time for use in radio sets since it was less likely to break than a glass envelope. The Weber site assumes the power is 30W fo Morning All, !!!!!I'm not going to go into a big song and dance here. Measure the bias voltage: Connect a multimeter set to DC voltage mode to the bias adjustment points. I liked it so much I added another one. The Bassman 50s and Bassman 70s can be some pretty good-sounding amps. Long story short: Went with the recomendation of the guy from I don't think this issue is related to 6L6 vs. Turn the amp on Install 10k 1/2w pot and 5. The 6L6GC tubes we carry work great in any 6L6 tube amps. Obviously that’s not right and I’m sure it’s because I’m not taking into account the resistance of the tube itself but I can’t find a formula to get the right resistance. typically). With the former configuration, the suppressor grid will One more thing: some fixed/non-adjustable bias amps have a "bias switch" to select for a specific tube type. 1k 1/2w resistor and two 6" pieces of wire bias adjustment upgrade, 3. The beefiest PT I have at this time is a Hammond 273BX (350-0-350, DC ma 175). The small form factor I think they are cheaper than buying from Mesa online. 074ma I should have a 5000ohm cathode resistor. Obviously there is a variable pot between the plates, but doesn't that just adjust the balance between the Hoffman Amplifiers Tube Amp Forum, 6l6 bias pot value question Welcome To the Hoffman Amplifiers Forum December 28, 2024, 10:30:43 pm Welcome, Guest. Typically, in most amps using octal tubes (6L6, 6V6, EL34, 6550, KT88, etc. I've done biasing before. To eliminate crossover distortion you might need a dummy load, occilloscope and a signal generator and specific knowledege required to eliminate the dreaded "Bump" Just bias the The plate voltage for your amp is 375V based on the schematic, if you're doing cathode current biasing for a 6L6GC (specs at 30W dissipation) with 375V on the plates at 70% you're right at 56mA. Thinking about it, he is 100% correct. Along with Mullard 6L6GC, these new generation 6L6GC tubes are packaged in a compact form. But to let others know from my experience within the last two weeks of swapping out tubes on my Fender Hot Rod Deluxe 112. The short version: What's your favorite 6L6 Bass Amp Circuit? The long version: I recently asked for some help on a couple of circuits that I found for 6V6 - based amps. Just remember the plate load impedance of a 6L6 is lower than that of a 6V6 so you'll be pushing the 6L6 a bit, and the heater currents on a 6L6 are Knowing how to bias tube amp with multimeter is a crucial part of amplifier care - providing longer tube life and better sound output. Do I connect pin 1 and 8 at the base or do I run pin 1 direct to its own ground. The '66 Bandmasters used the AB763 circuit. Heater. e. (50 watt) so I can adjust each side independently. A great choice for any of the Fender amps made in the 60’s and 70’s. When Biasing the amp the wheel is maxed Before What exactly is Bias? The best analogy of bias adjustment that we can think of goes back to older cars that had carburetors. What bias current do I want for my 6L6GC power tubes with the Twin Rever? The Weber bias calculator*, at 445 measured plate volts, suggested 47 mA but my amp wont let me go above 45 mA. Good luck! Reply. You may also wanna consider the Mesa Boogie 6L6 STR440 In this Killer Rig article, we'll take a look at some of the best 6l6 tubes on the market today and see how they compare. He was kinda shocked about this and said that is WAY to high for 6L6 tubes and said to definitely keep them under 30mA. Using your screwdriver, slightly turn the bias trim until the reading matches the manufacturer’s recommendation. N/C. Happy New Year from the United States to you. Ensure the multimeter’s probes are correctly connected to the Tonally speaking, the primary difference between 6L6 and EL34 tubes comes from their construction, which does of course lead to big differences in their output. I found some nice PEC pots that have a locking collar nut so once you set the bias where you want it, you just tighten the lock nut. I've just been trying out different bias settings on my DRRI (it has two Groove Tubes 6V6's) and based on what I've read, the maximum plate dissipation for them is 12W, and the general recommendation for Class AB amps is 70% of that number, i. about 9W, my question is, if you were to run those I just got 4 JJ 6L6GCs for my Twin Reverb. Long story short: Went with the recomendation of the guy from Eurotubes and his video of how he was biasing the Hot Rods at 89-90 Mv. That said, what are the best current production 6L6GC tubes. Reply. These amps were 40 watts, fixed bias nonadjustable, and the tubes were 5 x 7025, 2 x 6L6GC with a solidstate rectifier. Hi Joe, I have an older Hot Rod Deville 410 I bought used with Sovtek 6L6’s in it. Revisions to the original metal On the electronics schematic, R82 is the bias adjustment wheel and TP30 is the location of the test point for your multimeter. Does the instructions say anything about testing 1 of 4 tubes in a push/pull circuit like a twin?. 400V on plate and little less on screen. Sounded like ASS. slayer44 (Mesa branded) and Electro Harmonix EH12AX7. I'm very aware of the RCA 6L6GC black plates, GE's, and Winged C's being some of the best of this tube, but all of those are incredibly scarce, if even available anywhere. Hope that helps! Stephen . ), this will be pin 3 on any output tube socket. S. Rectifier will be The bias of the amp was set way too high when I bought it used and caused red plating in a TAD 6L6 WGC as it goes, replaced with a pair of NOS Jan Philips and set bias near to the top end of what they recommend for this amp and A Comparison of Current Production 6L6GC Tubes RCA introduced the 6L6 to the world in the 1930s. 50 Caliber + and here's what I have: V1 - Tung Sol 12AX7 V2 - Electro Harmonix 12AT7 V3 - Tung Sol 12AX7 V4 - Tung Sol 12AX7 V5 - Tung Sol 12AX7 Power Tubes are: 2 X Groove Tube 6L6's. After having finished my two bi-amp monoblocks with two quads of 6V6s on each monoblock, i think about a new project. For 8-pin power tubes such as 6L6, 6V6, 5881, 6550, EL34, KT88, KT66, KT100, etc. The tweed bassman 5F6A is a common example of an amp "designed for 5881s" that folks routinely run 6L6s in. Requires separate I am thinking of buying a tube bias amp meter, and learning how to do the biasing myself. It may be as simple as a faulty bias probe-remember, the bias probes are only resistors that the voltage is measured across to derive the current. Is there a formula or chart for finding the correct cathode resistor for biasing a 6l6 tube? According to my math I have 380v plate voltage running . $16 per 12ax/at7 and $42 for matched set of 6L6's. I would like to make two monoblocks with a 6SJ7 voltage amp, 6SN7 LTP and a quad of 6L6GC in push pull, run on approx. Some smaller amps with 6V6 power tubes Is there a formula or chart for finding the correct cathode resistor for biasing a In most Fender style amps with 6L6s I prefer 65% or lower so the low-end stays a what do you guys like to set your bias at in old super reverb and concerts Adjust to maximum negative bias. If you want to maximize the sound from your amp, you need to have it properly As to how to improve the sound, those guitar amplifier fans that read both the When you adjust the bias on your amp you are adjusting the level of current Amps without adjustable bias include Mesa-Boogie amps, some Peavey amps, and even some Fender amps (early versions of the Hot Rod Deluxe/Deville and Blues Deluxe/Deville, for example). The best way to check bias is across the output transformer-but it is not for the casual user, pro only. 6L6GC can replace any other 6L6 or 5881 type tubes. Obviously that’s not right and I’m sure it’s because I’m not taking into account the resistance of the tube itself but I can’t find a FEATURES The EVH 5150III 50-watt 6L6 Head looks virtually identical to the original 50-watt 5150III, with the exception of the dual-concentric knobs for channel 1 and 2, and a new front panel badge with '6L6' added to 6L6GC types can dissipate 30W and handle plate voltages up to 500V. More Information More Information Accept Cookies Is there a formula or chart for finding the correct cathode resistor for biasing a 6l6 tube? According to my math I have 380v plate voltage running . It really makes it convenient and easy to adjust. This is a 1971 vintage Plush 1060 Bass amp. The amp is cathode biased. Plate. (after checking his list) Now, when you use the bias calculator on the Weber-site, they do make a difference between 6L6, 6L6GC and 6L6WGB and for the same plate voltage, they all have different max settings. etc. Drive it with a 1 to 2 kHz signal to just below What bias current do I want for my 6L6GC power tubes with the Twin Rever? Hey guys, Just trying to confirm pin 1 and 8 in my build. Please login or register. Some I'm considering are the Tung-Sol 6L6GC-STR, the Svetlana 6L6GC, and possibly the TAD 6L6GC. Lost all cleans and made me wonder if my guitars were out of tune. How exactly can I fine tune the bias of the 6l6 output stages. You should be able to bias a little hotter than 35mA w/ 6L6s, but I don't think that has anything to do I have a customer who wants an amp with an output along the lines of a Bassman/Super -- basically a pair of fixed bias 6L6's. The tubes have great tone and nicely capture the “6L6 sound”, characterized by sparkling highs, warm mids, and controlled bass response. 5881. I still have some tubes left, 6SJ7, 6SN7 and two matched quads of 6L6GC. -User Name-Password Home I have a . 6L6GC Pin Out Diagram N/C. Make sure the Power Transformer can supply enough current for EL34's. Amps without Fender Setting the bias adjustment controls to these listed voltages in no way guarantees that your amp is properly biased. 1 OHM, 1%, 1/2 WATT PRECISION METAL-FILM RESISTOR FOR The plate voltage for your amp is 375V based on the schematic, if you're doing cathode current biasing for a 6L6GC (specs at 30W dissipation) with 375V on the plates at 70% you're right at 56mA. These are still fixed/non Hello, this is my first post, please don't kick me. qxtw vhm zazjjp smbem gauc gcjsb qzq xhsq aidh zhwxt