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jegler last won the day on May 13 2014

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  1. I searched several of the big mailorder music companies today - there were NO new DT 50 units available. Has it been discontinued?
  2. Has the DT 50 been discontinued by Line 6? I searched several of the big mailorder music companies and there are no new units available. wtf? does that mean the dt 25 is doomed as well?
  3. It's cool - I appreciate your followup and input. (pssssst - you could always mssg me regarding my pv procedure question wink wink nudge nudge simple yes or no even - I'll keep it off the forum.)
  4. Ok - I'm fine with taking your advise about using the recommended 25mV bias and not bothering with setting at 70%. And you offered plenty of specifics on why I should, so thanks for that - but you still didn't address any of the specifics of the procedure for checking the plate voltage on the DT. I probably won't bother at this point now that I understand the lack of benefits, but just for science's sake I'd like to know since this is still somewhat mysterious. I'm just trying to educate myself and by proxy the other members of this forum, and right now theres just a bunch of my speculation posted on that procedure. Can someone please, PLEASE address that, so we can put this to bed entirely? Thanks in advance...
  5. I'm glad to have you address this thread, but you're not being specific about any of your vague warnings against taking a measurement on my amp that will inform me about where to set my bias. The OP was of the mind that setting bias at 70% was the way to go. And assessing the plate voltage was part of that measurement. It seems like a really simple and relatively safe procedure, IF you know the procedure. Is my procedure wrong for measuring the plate voltage on the DT? Is measuring the plate voltage correctly on the DT somehow harmful? (for the amp OR the operator) Do the calculations for obtaining your 70% value pertain to the DT? e.g. ((Max Dissipation / Plate Voltage) * 0.7) * 1000 = bias mv I'm paraphrasing here but, OP claims that 70% lets the amp run cooler and could be beneficial to the longevity of the DT. And 70% bias setting has been kinda the "standard" bias setting for tube amps for decades. We know that the published bias recommendation for the DT25 is 25mV+-3. OP's measurements indicate that's up in 90% range (for his amp, anyway) 70% would obviously be more in the 21mV range. Which would presumably run cooler. I am using "cooler" in thermodynamic terms, although I understand that there is a tonal component as well. Is there any truth to the notion that 70% will run cooler on the DT? e.g. 21mV bias runs cooler than 25mV bias Are you saying that running your bias at 70% could be/is harmful to the DT? Or are you saying, officially, that a 25mV bias setting will run plenty fine on my DT25 for years and years of awesome, juicy tube goodness and that it'll save me the time and brain power if I just don't bother with it cause it won't make any difference for the better? If you answered those important specifics, or any of the specifics I've brought to the discussion, we could maybe put this investigation to bed and get back to rocking out. I appreciate your expertise.
  6. I'm guessing you're probably under corporate obligation to dissuade modifications for liability purposes. I'm not trying to mod the amp, and my warranty's been over for a long time. So - just trying to make the DT run lean. I want it to last forever. I love this amp. I would never hurt my baby. Which is why I turn to you experts on the DT forum.
  7. Please add/edit Measuring plate voltage on a DT 1) Remove power tubes with amp unplugged from AC. 2) AC Plug in, speaker connected, power and standby both on. 3) Class A/B, Master vol down 4) DMM set to DCvolts @ 500V 5) Black clip to chassis, Red to pin 3 6) Note voltage 7) Power down, unplug AC and put tubes/everything back together again. From there, math and Ohm's law tells me where to set my 70% bias for my DT. Izzat about right?
  8. I understand that there is no way to get inside the chassis to measure the plate voltage with the tubes in. But it sounds like it can be done with the tubes removed from the socket. I'm pretty sure I can clip my DMM black probe to the chassis and red probe goes to pin 3. I think at this point I just need to know if I need a speaker load connected when the tubes are out and I power on. Also does it matter if I'm measuring from V2 or V3. Hopefully spaceatl will weigh in with something useful.
  9. Im trying to measure the plate voltage, not the bias voltage. If I can do it with a multimeter, the only difference between me and "the pros" is the correct knowledge. You guys are the pros, so school me. I already did some research, I just need you guys to help me take it to the hoop.
  10. 1) I'm trying to get assistance from you! 2) some other dude from some other forum? c'mon, it can't be too awful bad. look at it this way: if I succeed, I can't sue you, if I fail, I'll be dead and can't sue you. You are clearly an expert and have experience with this specific task and this specific amp. Pretty Please? the stuff I found on other forums is specific to other amps. This is from the Marshall forums: close-Enough Plate Voltage can be Taken with Power tubes in place, If you want dead-nuts-on remove the tubes. Set Your Meter to DC Volts in the range that applies (+500VDC) Both Power switches ON, Ground the Black lead to Chassis, Red Lead to Pin 3. BE EXTREMELY CAREFUL, You can DIE. Best to Clip the Black Lead on and use the red probe with one hand, Keep the other hand in your pocket. it seems intuitive that I would be measuring with the tubes removed from my DT25 combo. Do you have a speaker load connected? Are you measuring from pin 3? Pin 7? Can you confirm if this pin numbering diagram for EL84's is accurate? And if this is wiring side of socket shown, do I have to horizontally flip the image to get an accurate picture of what I'm seeing as I look at my amp sockets from the plugin side?
  11. Has anyone any experience using SStubes with the DT25 in the V1 socket? From the mnfctr site: Before you buy, make sure that the anode (plate) voltage in your device at is least 30V. the DT is ~ 400V right? Still no SStube equivalent for power tubes.
  12. Can I do this with just a multimeter? If so, could you give some details as to exactly how to proceed with measuring my plate voltage? Y'know without electrocuting myself? Don't want to go probing dangerous holes. I am interested in implementing your 70% philosophy with my next tube change. Thanks for spreading the knowledge.
  13. I can tell you that upon my latest tube change, I started with V2 about 22mV and V3 around 27mV. when I stepped through my HD500 presets, any patch that used Voice III on the DT (which is the only voice where I use Class A) they were lower in volume than before the tube change. I swapped V2 and V3, hoping to bring the voltages closer (didn't), but with the hotter tube in V2, my patches were all leveled again. I had created the patches using a pair of tubes where V2 was hotter. This leads me to believe that, at least with class A/Voice III, one needs to take into account tube voltage along with everything else when leveling patches. One more thing to keep track of...
  14. radatats link is no longer valid - this video details biasing DT25 combo, which is similar to the head:
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