Palico Posted February 21, 2017 Share Posted February 21, 2017 Just looking for some thoughts. I know the DT25 uses EH and that is the recommend from Line 6 as this amp is a bit of hot rod. I had a tube go bad on my Friday afternoon, no problems I had a spare EH tube I took out of the amp a while back because it had some discoloration on side of the tube, like slight burn mark. So I put it back in. All was fine. I had a show Saturday and didn't want to be without a spare as I don't exactly trust that tube to begin with. So I stopped by the local GC and picked up a set of Groove Tube EL84 match set for spares. Now I'm wondering without taking it to someone to bias (no one around here I would trust with this type of amp), would putting those Groove Tubes in hurt the amp or just wear out quicker? Not sure if should really order a new set of EH EL84 tubes for the best possible sound or if the Groove Tubes would be fine. Right now I'm kind of leaning towards just leaving the one questionable tube in until it gives me a issue, since I got two Groove Tube EL84 that could get me thought a show if they had to. Thoughts? Quote Link to comment Share on other sites More sharing options...
psarkissian Posted February 21, 2017 Share Posted February 21, 2017 "... while back because it had some discoloration on side of the tube, like slight burn mark"--- If it has a burn mark on the side, then it's "red plating",... remove the tube. There is a problem with the plate element and can damage other circuits. "... would putting those Groove Tubes in hurt the amp or just wear out quicker?"--- Love GT's, Aspen Pittman, who started Grooves Tubes is a friend and colleague. These are not all analog tube amps of the 1960's and 70's, you can't go swapping out for any tubes like we used to back in the day. These are optimized for EH's. Need to use the specified EH's. If it's "red plating" it needs to be serviced and checked for any other problems. And the specified matched set of tubes need to be put in and properly biased. Can't mix and match tubes like that, the amp will be damaged. Unmatched tubes result in distortions, which results in rapid wear-and-tear on the amp. Even more so since this is not an all analog tube amp of old. DT series amps that come back to me for repair and servicing with other than specified tubes in them,... ... come back to me because of use of the afore mentioned un-approved tubes (Mesa, GT, JJ, and the odd Ruby and Tung-Sol). 2 Quote Link to comment Share on other sites More sharing options...
Palico Posted February 21, 2017 Author Share Posted February 21, 2017 "... while back because it had some discoloration on side of the tube, like slight burn mark"--- If it has a burn mark on the side, then it's "red plating",... remove the tube. There is a problem with the plate element and can damage other circuits. "... would putting those Groove Tubes in hurt the amp or just wear out quicker?"--- Love GT's, Aspen Pittman, who started Grooves Tubes is a friend and colleague. These are not all analog tube amps of the 1960's and 70's, you can't go swapping out for any tubes like we used to back in the day. These are optimized for EH's. Need to use the specified EH's. If it's "red plating" it needs to be serviced and checked for any other problems. And the specified matched set of tubes need to be put in and properly biased. Can't mix and match tubes like that, the amp will be damaged. Unmatched tubes result in distortions, which results in rapid wear-and-tear on the amp. Even more so since this is not an all analog tube amp of old. DT series amps that come back to me for repair and servicing with other than specified tubes in them,... ... come back to me because of use of the afore mentioned un-approved tubes (Mesa, GT, JJ, and the odd Ruby and Tung-Sol). Okay so I need to order me a set of EH tubes for it, and likely a spare set. GC list has as a Hard/Medium/Soft type for the EH EL84. I assume use the Medium ones? Oddly Tubestore doesn't have that option of Hard/Medium/Soft. Quote Link to comment Share on other sites More sharing options...
psarkissian Posted February 21, 2017 Share Posted February 21, 2017 Yes,... go with the mediums. That's what we use, that we get from EH. Has to do with the proportion of vacuum vs gas,... Soft--- more gas (a gassy tube), less vacuum, saturates more easily, so it distorts more easily. Hard--- less gas, more vacuum, higher saturation point, harder to distort and so more headroom. Medium--- in between, has good headroom, but will distort if you push it. 1 Quote Link to comment Share on other sites More sharing options...
SymphonicDischord Posted February 26, 2017 Share Posted February 26, 2017 I'm just curious here, I retubed my DT25 head about a year ago and did quite a bit of extensive research at the time and do not recall there being any specific tube type recommendations. As this was the case, I went ahead and ordered from The Tube Store a matched set of Preferred Series 7189 (http://www.thetubestore.com/Tubes/EL84-6BQ5-Tube-Types/Preferred-Series-7189-Premium-EL84) and a Sovtek 12AX7-LPS (http://www.thetubestore.com/Tubes/12AX7-ECC83-Tube-Types/Sovtek-12AX7-LPS) for the pre. I installed and biased everything correctly and have been using the head with these tubes in on a fairly regular basis since then. I guess my question is, is there any warning signs that I should be looking for that they didn't take as well as I initially thought? Should I put the old tubes back in as they are still good? Thanks in advance for the help. Quote Link to comment Share on other sites More sharing options...
psarkissian Posted February 27, 2017 Share Posted February 27, 2017 Every time I get an amp back with something other than specified tubes, its failure end up turning out be the reason for the failure. These are not all analog amps, these are hybrid analog/digital amps. You can get away with doing the kind of tube swaps like we used to back in the 1960's and 70's, with all analog tube systems. Use the specified set of EL84 (matched pairs) and 12AX7 Electro-Harmonix tubes, mediums. If The Tube Store tells you that EH is just a Sovtek with EH painted on it, and that you don't need the EH's. Mike Matthews of EH has told me on more than one occasion, that EH owns the Sovtek factory in Russia. The EH tubes go through extra scrutiny and testing, required for our products. The Tube Store knows tubes, they may not know our amps or what they require,... I do. Best to use the specified tubes, so that I won't have to see your amp on my bench. 2 Quote Link to comment Share on other sites More sharing options...
CraigGT Posted February 28, 2017 Share Posted February 28, 2017 That's a very passionate reply psarkissian and one that I will file away for the future when I may need new valves (I'm British btw ) :-) Craig Quote Link to comment Share on other sites More sharing options...
psarkissian Posted March 1, 2017 Share Posted March 1, 2017 Where abouts? Quote Link to comment Share on other sites More sharing options...
CraigGT Posted March 1, 2017 Share Posted March 1, 2017 Yorkshire, we use valves here :) Craig Quote Link to comment Share on other sites More sharing options...
psarkissian Posted March 1, 2017 Share Posted March 1, 2017 Haven't been there yet. I hang about in Chelsea, Earls Court and The West End. Sometimes Daventry and Rugby. One of our techs hung out his own shingle in Northampton when we closed our UK location. Still stay in touch with my mates there (and the ex-pats here). I normally say valve, but there are some of us yanks not gotten into the habit the way I have. UK, my fave place. The Bard, The Theatre there, can't get enough it. :) Quote Link to comment Share on other sites More sharing options...
CraigGT Posted March 1, 2017 Share Posted March 1, 2017 Cool story, I'm about 200 miles north of London. We normally visit a couple of times a year, last year was to see David Gilmour at the Albert Hall and this year we're going to see the Pink Floyd exhibition at the V&A for my birthday! Quote Link to comment Share on other sites More sharing options...
psarkissian Posted March 1, 2017 Share Posted March 1, 2017 Daivd Gilmore,... niiiice. V&A,... go by there sometimes. Haven't stopped in yet. Quite a building though. If you need servicing of Line 6 gear, and don't want to go all the way down to E&M Electronics in Milton Keyes, there's Mark Wright Music in Northampton. Mark was one of our techs at the Rugby location we used to have. Now he's got his own shop. Have some friends and colleagues in Yorkshire. Also in London at QMUL (C4DM), Surrey, Cambridge (ARCAM) and Uni of Essex (ARL). Guess I'm well covered. Cheers, -P Quote Link to comment Share on other sites More sharing options...
CraigGT Posted March 2, 2017 Share Posted March 2, 2017 It sounds like you won't need to pay for any accommodation when you come over :-) Quote Link to comment Share on other sites More sharing options...
psarkissian Posted March 2, 2017 Share Posted March 2, 2017 :) Quote Link to comment Share on other sites More sharing options...
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