psarkissian Posted March 23, 2018 Share Posted March 23, 2018 Dear group, I can not emphasize this enough,...do not, do not, do not use anything other than the specified tubes (valves) in these amps. Power tubes must be matched sets. Use only the specified tubes. Please, I'm trying to keep your gear of of my repair bench, so you can make music and rock out. Thank you. 1 2 Quote Link to comment Share on other sites More sharing options...
elegault2 Posted March 24, 2018 Share Posted March 24, 2018 I've listened! Purchased and put in inventory, just in case. Glad to see an engineer committed to the community, good job man. Quote Link to comment Share on other sites More sharing options...
psarkissian Posted March 26, 2018 Author Share Posted March 26, 2018 Thank you. Have one on the bench now from someone who didn't listen. A number of items to replace as a result. It didn't have to be. Quote Link to comment Share on other sites More sharing options...
psarkissian Posted March 28, 2018 Author Share Posted March 28, 2018 Tubes choices to use for the DT Series,... DT-50 Series: 12AX7EH Electro-Harmonix approved for the DT50 pre-amps. EL34EH Electro-Harmonix (matched pairs) for the power amps. DT-25 Series: 12AX7B China for pre-amps. EL84EH Electro-Harmonix (matched pairs) for the power amps. Soft, medium or hard, the ratio between vacuum-to-inert gas in the tube,... all tubes used have to be mediums. Power amp tube choices are crucial, and must be properly biased by a tech or Line 6 authorized service center who knows the product. Don't do this yourself, the shock hazard is too great,... and it hurts when you get electric shock. Leave it to a tech trained who is for this. These valve amps are particular about tubes and tube brands. Do Not use substitutes, No Mesa, Groove Tube, Tung-Sol or JJ or (etc) substitutes. No hot rodding of an already Bogner hot rod. 2 2 Quote Link to comment Share on other sites More sharing options...
jegarcia Posted April 18, 2018 Share Posted April 18, 2018 @psarkissian For the DT25 you mentioned 12AX7B China. So I take it that any manufacturer is ok as long the tube is from China? Quote Link to comment Share on other sites More sharing options...
psarkissian Posted April 18, 2018 Author Share Posted April 18, 2018 Sovtek is preferable. The Sovtek factory is owned by Electro-Harmonix. The Sovtek may have "LPS" as a suffix, that's fine, it just means it's a low microphonic version. And that's a good thing. Quote Link to comment Share on other sites More sharing options...
jegarcia Posted April 18, 2018 Share Posted April 18, 2018 @psarkissian I thank you sir Quote Link to comment Share on other sites More sharing options...
psarkissian Posted April 18, 2018 Author Share Posted April 18, 2018 No problem. Quote Link to comment Share on other sites More sharing options...
jegarcia Posted April 20, 2018 Share Posted April 20, 2018 @psarkissian Sorry I noticed something. This link has the same info but it mentions the pre-amp tube is the chinese made 12AX7. You mentioned 12AX7B. What is the difference? Quote Link to comment Share on other sites More sharing options...
psarkissian Posted April 20, 2018 Author Share Posted April 20, 2018 "12AX7B China" --- is typically from China that we use. But you can also get the Sovtek/EH versions. EH's are Sovteks that go through more scrutiny. And since EH owns th Sovtek factory, it's all the same company. Some of our China "B"s are sourced through either EH or another source (maybe Ruby Tubes, I forget who). Quote Link to comment Share on other sites More sharing options...
spaceatl Posted May 9, 2018 Share Posted May 9, 2018 hmmm...Sovtek does NOT have a factory...Just another New Sensor Brand Name for tubes that come from Xpo-Pul factory (Reflektor) Saratov, Russia. ALL Mesa Tubes: New Sensor Xpo-Pul factory (Reflektor) Saratov, Russia Sovtek: Xpo-Pul factory (Reflektor) Saratov, Russia EH: Xpo-Pul factory (Reflektor) Saratov, Russia SINO (CHINA): factory Shuguang Electronics Group Co., China 2 Quote Link to comment Share on other sites More sharing options...
psarkissian Posted May 9, 2018 Author Share Posted May 9, 2018 EH owns the factory in Russia. I have this chat with Mike Mathews (owner of EH) every year at NAMM in Anaheim, CA. Chat about tubes and the the factory in Russia. I make my rounds of the tube people booths every year as part of my info gathering. Shuguang Electronics Group Co., China sounds familiar, see their name in tube info here and there. Quote Link to comment Share on other sites More sharing options...
spaceatl Posted May 15, 2018 Share Posted May 15, 2018 Actually, New Sensor owns the factory and the brands EH, Tungsol, Mullard, Genelex, Svetlana, Sovtek, Tesla and JJ....EH is nothing more than just another brand that is printed on the Russian tubes that ALL come from the same factory owned by New Sensor... 1 Quote Link to comment Share on other sites More sharing options...
psarkissian Posted May 15, 2018 Author Share Posted May 15, 2018 I'll have to remind myself to ask Mike Mathews about that hierarchy, next time I see him. I should have a chat with Dave Pearlman (Pearlman Micropnes) and Robert Moran a couple of fellow tube freaks who keep up on this, on a more daily basis than I do. And maybe have a chat with Aspen Pittman (founder of Groove Tubes) while I'm at it. I see them more often than Mathews. Thanks for the feedback. Quote Link to comment Share on other sites More sharing options...
spaceatl Posted May 16, 2018 Share Posted May 16, 2018 No problem...This is fairly well known and documented in many articles...If it wasn't for Mathews, tubes would be way more expensive than they are now...He saved the Reflektor factory and put it in American hands. I do not know him, but I have followed this since the early 2000s when it all went down... 1 Quote Link to comment Share on other sites More sharing options...
psarkissian Posted May 16, 2018 Author Share Posted May 16, 2018 I guess that my knowing the people in this, I don't bother with the articles, since I'm personally well acquainted with the sources. But it sounds like I need an update. So many companies merging, selling off, getting acquired,... you need a score card to keep track of the score cards. Hmmm,... Reflektor. I see Mathews once a year at the trade shows. But Robert Moran, Dave Pearlman and Aspen Pittman are Facebook friends and local to me, so I have more virtual and face-to-face contact with them more often. I'll pick their brains about this. Thanks. 1 Quote Link to comment Share on other sites More sharing options...
oscarguitar Posted May 27, 2018 Share Posted May 27, 2018 Just swapped the tubes out again on my DT25. 4th set of EH replacements. I gig regularly and I was disappointed with the sound of the amp recently, volume and bass was down, and wondered if a new set of tubes would make a difference. I checked the bais of the old tubes before swapping. 24.9 mV and 34.6 mV. So something was clearly not right. New ones biased to 25mV, gig last night and order is restored. Checked the bias again this morning and made a minor tweak. But the tone is back. That Laney 30BL is gonna have to wait. Quote Link to comment Share on other sites More sharing options...
Schuvwj Posted June 10, 2018 Share Posted June 10, 2018 If I buy my replacement tubes for my DT25 from you/Line 6 will I get the correct tubes? 1 Quote Link to comment Share on other sites More sharing options...
psarkissian Posted June 11, 2018 Author Share Posted June 11, 2018 Yes, that's all we would have are the correct tubes for our product. The tubes I listed above for the DT series can also be acquired from other tube retailers. Quote Link to comment Share on other sites More sharing options...
jegarcia Posted November 17, 2018 Share Posted November 17, 2018 @psarkissian. How do you go about purchasing the tubes from Line 6? 1 Quote Link to comment Share on other sites More sharing options...
psarkissian Posted November 19, 2018 Author Share Posted November 19, 2018 You check with Customer Support, but if it's not in our online store, then I would think we would not sell directly to end users for that item. It's more for service techs. https://www.fullcompass.com/prod/236797-electro-harmonix-t-el34eh-matchpair-pair-of-matched-el34-preamp-vacuum-tubes For the EL34 for the DT50 power tubes. https://www.fullcompass.com/searchresults.php?search_simple=true&txtAll=Electro-Harmonix+12ax7 For the 12AX7EH pre-amp tubes. 2 Quote Link to comment Share on other sites More sharing options...
psarkissian Posted January 28, 2019 Author Share Posted January 28, 2019 As always, have a Line 6 authorized tech do the biasing of the power tubes. There is a specific procedure for bias and other calibrations that are required. Quote Link to comment Share on other sites More sharing options...
dlr_41 Posted February 14, 2019 Share Posted February 14, 2019 I blew A fuse on my DT 50H. I'm figuring it was from age and not tube related as there were no symptoms of the tubes failing. If blowing fuses becomes regular I'll replace the power tubes my self. Will I need a dual test probe? I know it has only one bias adjustment, so do I average the mv between the 2? I know the it supposed to be 36mv. Tube recommendation above is acknowledged. Quote Link to comment Share on other sites More sharing options...
psarkissian Posted February 15, 2019 Author Share Posted February 15, 2019 Take it to a Line 6 authorized service center. It's not a self repair problem. Which fuse is it? Quote Link to comment Share on other sites More sharing options...
dlr_41 Posted February 16, 2019 Share Posted February 16, 2019 20 hours ago, psarkissian said: Take it to a Line 6 authorized service center. It's not a self repair problem. Which fuse is it? 1A/250, output fuse I think. But, it appeared in tact and I believe it may still be good. I replaced the fuse (finally arrived) and it would not power up. I'm quite sure now the transformer is the culprit. For me taking it to a service center isn't feasible. My nearest one was in Lynn Haven, outside of Panama city. I'm pretty sure they aren't there but will be rebuilding courtesy of Hurricane Michael. A bud has family there and they are rebuilding, he says not much was standing afterwards. My second service center is in ATL and a 4 - 5 hour drive. I haven't opened it up as of yet to check the other fuse because I'm willing to bet I'll have to order it as well. The down side of living peacefully in a rural area! Its really a shame, I bought this amp the later of 2016. I bought a house and spent the next 18 months getting it like I want it before I took time the time to play any at all with the exception of an hour or 2 here and there. I bet this head doesn't have 50 hrs max on it. I may end up going this route ( https://mytubeaudio.com/tag/new-transformer-line-6/ ) because all the research I have done has led me to believe that the OEM is a faulty design with low quality control. Biasing with dual probes will be out of the question and I will have to find someone with an oscilloscope after replacement. Its a great head, a true tone monster! Its me second one as I was forced to sale off all my gear several years back. I can't justify OEM after reading all the other horror stories! Quote Link to comment Share on other sites More sharing options...
psarkissian Posted February 19, 2019 Author Share Posted February 19, 2019 I'm looking at the serial number. Take it to a Line 6 authorized service center. It's not a self repair problem. Quote Link to comment Share on other sites More sharing options...
dlr_41 Posted February 19, 2019 Share Posted February 19, 2019 Yeah, must be one of the bad ones that the bulletin was about I take it? So, I drive 5 hrs to drop it off and 5 hrs back and wait a few weeks. drive 5 hrs to pick it up and pay a few hundred to have to fixed since its out of warranty. Then if I'm lucky, it'll last a couple of years. Ever get the feeling you've been hosed??? LMAO... This is giving me a great excuse to build me a 2204 or a JTM 45. I've been down this road before with only one other amp. It was a from the mid 60's. No matter what was done to that amp, it would blow tubes within 10 - 20 hrs. I think I had that thing in the shop so much it was practically rebuilt. The only saving grace was a guy loved it and offered me a lot of cash for it. I think I got a Mace or Deuce... not sure, it was the 70's and I acted accordingly! :P Quote Link to comment Share on other sites More sharing options...
dlr_41 Posted February 19, 2019 Share Posted February 19, 2019 I just talked to the guy at Pro tech services in Lynn Haven, they are open but the guy said they had problems getting parts from you guys and there were issues between you? Nevertheless, The tech that knows the gear and does the work is out and will call me when he gets a chance. Since I'll most likely end up paying I might as well have a transformer wound and have it put in instead. I really wish I had bought a back up amp instead of that JTV69S last month. I just hooked up with some guys and was trying to put something together. Such is life, huh? Quote Link to comment Share on other sites More sharing options...
psarkissian Posted February 22, 2019 Author Share Posted February 22, 2019 Certain parts are getting hard to get, other parts are more available. Wish I had more control over that. Quote Link to comment Share on other sites More sharing options...
peteandrebop123 Posted June 18, 2019 Share Posted June 18, 2019 https://line6.com/support/profile/1396597-psarkissian/ re: [L6TID: 350720] Line 6 Support Ticket. To @ psarkissian: Here’s my dilemma and I’d like your input. I know you’ll say, take it to a service center...ok, I got it. I'd just like to know if you or anyone else in this blog has experienced this issue: my DT25 started making cracking noises; it’d come and go over the period of a month or so. I could move cords/pots around and it would disappear. But last week it got really noisy, so I turned it off thinking it was bad tube. The next day I turned on the power, with all the volume pots OFF and in standby mode and I got an immediate nasty blaring sound. I checked for microphonic tubes...nothing, so I pulled power tube one (V2) and sure enough, there were white flakes dancing around inside the tube so it was blown. I replaced all the exact EH tubes but I have not powered it on. So...my question is: do you think (as I do) that it is in fact, just a blown tube, or because of that BLARING, could it be a blown modeling board? (as I’ve heard that was a problem a few years back). I have never experienced that with any other amp that had a simple tube issue. And no...the fuse did not fry...it’s perfect. Thanks Quote Link to comment Share on other sites More sharing options...
psarkissian Posted June 19, 2019 Author Share Posted June 19, 2019 " I have never experienced that with any other amp that had a simple tube issue. "--- This is an amp has a digital stage as well as an analog stage. These stages have to talk and be nice to one another. An all analog tube amp is different that way. Quote Link to comment Share on other sites More sharing options...
PDKTDK Posted July 24, 2019 Share Posted July 24, 2019 @psarkissian are there any warning signs on these amps when it is nearing time to change the tubes? Quote Link to comment Share on other sites More sharing options...
psarkissian Posted July 24, 2019 Author Share Posted July 24, 2019 Flickering of the elements, one glowing brighter than all the others, generally been in the amp for more than a couple of years if one plays occasionally. Too much distortion on a clean setting is usually an old or not correctly biased power tube. In general, if it's correctly biased and you're a weekend warrior in a band, or a living room jam player, chances are that once every 20-24 months should be a sufficient interval. Unless a tube goes in the interim. I've seen tubes last two weeks (crack developed and let the gas out), and I've seen tubes last five years (client treated it like a precious diamond in his audiophile system), it depends on what it's been through electronically and mechanically. Quote Link to comment Share on other sites More sharing options...
psarkissian Posted February 6, 2020 Author Share Posted February 6, 2020 Mike Matthews (of EH) still owns the company (https://en.wikipedia.org/wiki/Sovtek) that owns the Sovtek tube factory, last I talked to him. 1 Quote Link to comment Share on other sites More sharing options...
Guitarmaniac64 Posted February 16, 2020 Share Posted February 16, 2020 Not gonna order something from USA again the new added custom and taxes and shipping prices is ridiculous so i wonder if this tubes will work https://www.ebay.co.uk/itm/Electro-Harmonix-EL84-Valves-Tubes-PLATINUM-MATCHED-Pair-NEW-Burned-In-EH/322542352575?epid=1529268789&hash=item4b1905b8bf:g:OmwAAOSwK6RZM~33 Or those http://www.banzaimusic.com/EL84-EH-Platinum-Matched.html?gclid=EAIaIQobChMIre6In__V5wIVFqWaCh2RhAUhEAQYBCABEgIdwvD_BwE Quote Link to comment Share on other sites More sharing options...
psarkissian Posted February 18, 2020 Author Share Posted February 18, 2020 Those two links would be fine. Quote Link to comment Share on other sites More sharing options...
Guitarmaniac64 Posted February 27, 2020 Share Posted February 27, 2020 And i guess this ones works aswell as you wrote Sovtek is preferable in this thread. https://www.thomann.de/se/sovtek_roehre_el84_paar.htm Quote Link to comment Share on other sites More sharing options...
psarkissian Posted February 27, 2020 Author Share Posted February 27, 2020 Made by the same company, but the Electro-Harmonix tubes are a premium version of that tube that goes through extra tests with tighter tolerances, which is why we use them and specify them as the tube to use. They also have the correct soft/medium/hard specification we require for these amps. Subtleties that make all the difference between a well running amp verses an amp running on its edges. Same goes for the pre-amp tubes in the DT series of amps. Quote Link to comment Share on other sites More sharing options...
wijobe Posted June 13, 2020 Share Posted June 13, 2020 Can somebody please help me understand what is special about the Electro Harmonix version of the EL84? This version is hard to get in Germany, which does not make it easy to have the tubes replaced in the amp. As an electrical engineer I always try to understand the necessity for certain measures. In this case, which are the unique data points of these tubes that must be given? And I'm not talking about 'cleaner sound', 'more bass', 'less noise' or something like this. I am talking about fact based data, such as maximum ratings, plate voltage, bias, current, temperature, etc.. There are 'flavors' of the EL84 which are being sold in Germany, like the EL84M (military version by SOVTEK) or the EL84-STR, sold by Thomann (https://www.thomann.de/de/tad_rt872_roehre_el84_str_paar.htm). Would these be sufficient? Does anybody have experience with these? Looking forward to an answer! Wilfried Quote Link to comment Share on other sites More sharing options...
psarkissian Posted June 15, 2020 Author Share Posted June 15, 2020 "Can somebody please help me understand what is special about the Electro Harmonix version of the EL84? " --- Nothing special, it's what Rheinhold Bogner specified for the tube design. Don't use different flavors. Stick to the Electro-Harmonix Mediums version. Rheinhold designed the tube amp section, Line 6 has it's digital processor board in it. The characteristic curves of the tubes have to be spot on, because the analog side and the digital side have to talk nice to one another, or bad things happen. EH and Sovtek are owned by the same entity, the EH version is a premium version that goes through extra scrutiny, and so the characteristics curves are consistent. Variations between manufacturers or versions within same manufacturer can create inconsistencies. There is the soft, medium and hard aspect to also consider,... ratio of gas-to-vacuum in the tube also plays a role in this, and the characteristic curve (also know as transfer function) of the tube. As a result of the analog side and the digital side have to talk nice to one another, these amps are not forgiving of modifications, even tube swaps. These are not analog tube amps, so they cannot be treated the same way as all analog tube amps of 1960's and 70's. MIL SPEC tubes are nice tubes,... just, not in these amps. 1 Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.