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New Chinese tubes suck and you should know that! But this Headphone amp uses some of the best Triodes ever produced in its design and eliminates the output transformers to give you as pure of vacuum tube amplification as possible! Expect to replace the Chinese tubes immediately if you want the best from this amp. Then it is all about the headphones and signal you feed this amp! Find the best pairing of 6SN7s and 6080s you can for your headphones and you will achieve outstanding sonic reproduction rather inexpensively! Recommend trying some 1940-1950's JAN (Joint Army Navy) tubes for best results! Lots of these very high quality NOS tubes still available at reasonable prices! I had bunches of both 6SN7s and 6080s in my stock to use, so I purchased 2 of these amps! These amps do smell odd during their initial burn in period. Some chemical smell does vent off and I recommend doing like a full 72 Hour initial burn in to eliminate this smell as best as possible. Get some tested NOS JAN tubes and use these when you 1st power up your amp and just turn it on and leave it on for like 3 days before turning your new amp off! You can shut off your computer or whatever input you are using on it, but just let your new amp burn in fully during its initial power up! This should help your new amp last as long as possible in the long run, believe me. ;^) Your already tested NOS replacement tubes should not draw excessive current or fail quickly like the "new" Chinese tubes could possibly from poor quality control standards. Your new amp's transformer and tubes will get quite hot after about 30 minutes use! The 6080 uses 2.5 + Amps of 6.3 VAC just to light it's heaters. With the 6SN7s heaters added this amp pulls over 3 Amps of current just to light the tube heaters! But do not turn it off now as this is actually good for it! The new amp will vent that funny smell now. Letting things heat up and settle in while cooking that smell off is much better for it than keeping turning it ON/OFF initially! If you got a poor power transformer or Electrolytic capacitors in your new amp you want them to fail now so you can return it immediately! Using quality JAN tubes and doing a complete burn in should eliminate that funny smell and give you a GREAT sounding amp that will last a very long time!
I agree with the idea of ‘burning in’ the amp at idle since most failures from poor construction will likely reveal themselves in a day or two of operation. However, your sweeping generalization of tubes is a little much. But my real problem is with your statement about how much current this things draws at idle. Three amps!? Please. Read a spec sheet on a power transformer, or just use your head. That is a LOT of current even if this thing had an OT. This thing can’t possibly pull more than 750 mA I would guess. Opinions are one thing, but if you don’t actually know something just leave it be.
Maybe take your own advice? The 6080 takes 2.5A of 6.3V AC or DC just to light its heaters. The 6SN7 takes .6A of 6.3V to light its heaters. That means the tubes are using 3.1A of 6.3V just to light the tube heaters minimum. This is where the majority of the heat generated by this amp comes from. The 6080 won't use more than 250mA of HV DCV maximum and probably far less than that at normal operating levels.
I actually do know what I am talking about regarding tube amplifiers. Can you say the same?
hello, i wanted to ask you this. What tubes would you recommend for this amp to avoid such heat generation plus give you the best sound for your money?
Did you see my offer for upgrade tubes? No tubes will change the heat problem. A fan as I recommended in my other comments is the solution. Check all my comments and then get back to me ok?
Where do you recommend looking for tubes
I have them and will guarantee their performance and quality. You can get cheap tubes wherever, but you want some quality ones tested in my DV prior to shipping? Let me know what you are willing to pay including shipping and I'll let you know if I'll sell for that price. email@example.com
Hi there! I just got my DV today and turned it on for an initial two days of burn-in like you suggested, but around 5-6 hours in, it quit on me. I'm in the states and the box says it's a 110V unit. Do you have any advice on what to check on first? I saw in another comment thread something about replacing fuses, but I don't have the electrical background to make sense of what kind or how to access them. Thanks for any help!
Under the cord is spot for the fuse. It is probably blown. Replace the fuse with the same type and try it again. Make sure you put a fan on it if it starts back up this time!
Thanks! I replaced it with the provided spare (so handy!) and that one blew immediately. Also found a bit of a jangly "busted light bulb" noise in the 6SN7 tube. I'm guessing that's not normal, but could a bad tube cause the fuse to blow?
Pull both tubes, replace fuse, see if it still blows. If so, BAD. If it still runs without tubes you may need to buy some good tubes from me, or elsewhere, to fix it.
Will do. Thanks for your help. Fingers crossed!
Looks like I've got bad news. Threw in a new fuse without tubes and it blew immediately. What's next? :/
Power transformer appears to have overheated and shorted now. Warranty claim only option left. 8^(
The power transformer is by far the most expensive component of this amp. Transformers often use a kind of wax paper as insulation between wire windings in the PT. If the insulation breaks-down from excessive heat the transformer will fail from the winding's shorting together. You should have followed my fan cooling recommendations. The design of this amp gets far too hot without forced air ventilation, IMHO. The 6080 tube can get as HOT as 500 F! It might be a better, non-traditional, design if the tube sockets were reversed to keep the 6080 as far as possible from the PT to limit heat transfer. Or at least add a little fan to the design. The laptop cooler fan blows cold air up from the bottom dropping the operating temp of the amp immensely! I've been using a 12VDC wall wart and the fan from a blown computer PS. I set the amp right on top of it and it makes a HUGE difference. Without a fan the amp gets so HOT you can't even touch the PT. So it gets hot and its insulation fails and the PT dies. My only real complaint about this amp. Good luck with your return!
Thanks! I've already received a return label, so it should be fine. Just gotta wait for the next drop now, since they don't have any extras. I was actually keeping tabs on the temperature while it was on and the transformer never felt hot to me. The thick metal top of the unit was a pleasant kind of warm, but I didn't notice anything besides the tubes getting too hot to touch. And having heard of people having a unit for years and never a problem, it seemed like overkill to go to the effort of buying a tiny fan to put under the amp and run a cord to it. If six hours of running would cause the issue you're talking about, wouldn't it be more common? Is my case just a quality control issue with the placement of the insulation? I don't doubt it gets "too hot", but I'd be confused if after a few iterations of this amp and over 10 years of production and diy'ers the heat wouldn't be accounted for in the design or have an established mod developed by the community. It seems no one else is talking about it.
QC is the biggest problem with Chinese stuff. I just got mine recently so I don't have long term experience with the DV. My DV's get excessively HOT without cooling, IMHO. Your's could have been a tube failure that killed your power transformer. What is that fuse there for if not to prevent the PT's failure? There is another recent report of the power supply failing a 2-3 day burn in period like yours. Having the most expensive part of the amp showing excessive failures seems to be a problem.
Thanks for the excellent advice to run a cooling fan! Can you describe what it looks like to experience a tube failure? I'm new to tubes and wondering about longevity and what signs to look/listen for that indicate a problem. Do you also have the specs for the fuse for the Darkvoice? Thanks in advance!
Tubes can fail many ways so no. But there are some common failure modes. Heater shorts are 1 that is hard to see. If you run the Output tube too hard they will RED plate. Red plate too long the tube will melt internally and then the glass will melt too! Some failures are subjective. Noisy and microphonic, where they react to any bumps or vibration with sound output, are subjective failures. The fuse in my DV is 250V @ 3 A.
1 other thing. A well designed circuit that does not try to push a tube beyond the manufacturer's specs can run tubes constantly for many decades and the tubes can still test as new. Hi-Fi amps tend to be made this way, guitar tube amps can be designed to push tubes beyond specs to get "that" sound, so can need tube replacement rather often for hours used. If a Hi-Fi amp is needing it's tubes replaced often either it is of a poor designed circuit or there is another issue that causes the tubes to fail prematurely.
Hey Paraglider, do you know what type fuse and rating is correct? It's the same fuse in both voltage versions of the amp, right? I'd like to know so I can have a replacement available if ever the one in my unit blows.
Same fuse I listed above should work on both. Blowing fuses is a bad sign so you shouldn't need more than the 1 extra.