If you have a Dark Voice 336SE headphone amp you likely had the same thought as many other owners. Why does such a nice little amp come with such poor vacuum tubes? Well most Chinese made amps do come with cheap Chinese tubes because they are readily available. Unlike some Chinese amps that use obscure tubes with limited or no western equivalents to upgrade to, the DV-336SE uses tubes that have many substitution/upgrade options. It’s most common to upgrade the 6SN7 tube. We won’t get into which tube sounds best in this article though. Rather I want to address the common problem folks find when installing their new or NOS 6SN7 tube. With rare exception, there is a noticeable hum in the left channel. This will occur with any 6SN7 tube. But the good news is that after burn-in they will become dead quiet again. Here’s what to do:
1. Power off the amp and remove the 6AS7/6H13C power tube. This will keep the unit from over heating during this burn-in procedure.
2. Install your new 6SN7 tube and power the amp on again.
3. Wait. And keep waiting. We find that approximately 72 hours will do.
4. Power off and re-install the 6AS7 / 6H13C power tube.
5. Connect your favorite headphones and power the amp on.
You should find the hum in the left channel has completely disappeared. At the least you’ll notice it’s much quieter and likely only need one more day to get it completely quiet.
I realize you can modify the amplifier and add a couple capacitors to solve this but the instructions above will “fix” it for free so give it a try.
Thank you very much for infor
I have a question if you can please answer for me a Jan Philips 6922 with green writing on the tube is the same quantity or is the same tube with the blue writing a better tube
Our current selection has green labels. They are the same as tubes with blue labels, only made in a different year but mostly all were made in the ’80’s. The construction is identical, Philips did not change the tube design over this time, only the color of the logo.
This worked perfectly for my Northern Electric 6SN7. Approx 36-40 hrs of burn-in completely eliminated the hum/buzz.
6SL7#6SN7# are very similar pin number
Can you explain of these differencies
chararacteristic for all users ?
6SN7/6SL7 tubes are not in anyway compatible with 6AS7/6080/6H13C tubes. Although both are dual triode tubes, the latter is a power triode type and the circuitry required will have very different requirements than 6SN7/6SL7 tubes.
When you burn in are you leaving the power tube out and only burning in with a driver tube?
Thanks for the question. Detailed steps are included in the article above.
Are you saying that the power tube does not cause humming and therefore no need for a burn-in ?
Do you leave it 72hrs straight or power it off each X hours for Y hours ?
Just turn it on and let it go the full 72 Hours
What headphones do you reccomend for the dark voice 336se?
I was looking into the 990s 600 ohm and the 880 600 ohm. As well as the HD600/650. which ones do you listen on? i see you have some beyers in the picture which one is that
The headphones in the picture are Beyerdynamic DT990 that one of our staff uses. Honestly we are not in the headphone market and preference is very subjective so it isn’t possible to give recommendations. I personally have used AKG, Sennheiser, Master & Dynamic, Beyerdynamic, Audeze, Oppo and Grado (to name a few). We couldn’t say any one was better than the next, just that they are different.
Is it possible to run the Darkvoice as a pre-amp without the 6AS7 installed?
No the preamp section uses both tubes so the 6AS7 must be installed.
I’m very new to tube amps, so that’s why i’m struggling to find answers.
I know that there are official threads about Darkvoice, but they are too technical for me and i ‘ve found many many informations but still not a simple straight one..
I just got today my Darkvoice 336se with the power big tube broken so I need to buy a replacment but i want to be sure to buy one that will work ,
RCA 6SN7G seems popular.
Apologies that should have read 6AS7G not 6SN7G.
Drop us an email or give us a call 1-877-570-0979 and we can help you out.
I just bought a Darkvoice 336 used. It seems in perfect condition but has no manual. could you give me a website for downloading a copy of the manual. Thanks in advance, Jim
Sorry but we didn’t get a manual with ours brand new and could not find anything online.
The manual that comes with the Darkvoice is not really a manual but more of a history of how it was designed, and not really worth reading. You can find a translation of it here which includes the specs translated.
I have a Tung Sol 6SN7. Currently on my 90th hour. Still have a hum on the left channel. Should I just keep going or did I get a dud?
We have not experienced any issues with the Reissue Tung-Sol 6SN7 in this amp ourselves, but this is assuming you have a reissue and not an original Tung-Sol. If you had hum in both channels and it is now reduced to just the left, it is possible that it is an issue that cannot be rectified by further burn in. We can only guess from this side of the keyboard. You may want to try a different Tung-Sol to be sure. Please contact us directly so we can discuss a warranty replacement if this tube from an order at our store.
I recently ordered and installed a Northern Electric 6sn7 in my Darkvoice. I immediately had a significant hum. Initially bummed out, I started the burn in process and was quite relieved that by hour 72, it was dead quiet again. The tube is turning out to be fantastic. Very revealing and musical. Just what i was hoping for. Thanks for this article, as I probably would not have gone straight for a 72 hour burn in, and thought the tube was a dud.
In case 72 hrs burning process is not an option (safety reasons, nobody home at times), will a tube with significant hum in both channels (EH Gold, reissue), burn in from 1-2 hrs listening sessions? Tnx
If you are following the instructions there will be no issues with heat generated from the equipment as the power tube is not installed and anything generated by the 6SN7 is very minimal at best. Personally we would not consider it a safety concern but advise you do whatever you feel is best in your situation. As for the hours, it is 72 hours total of burn in that is generally required to dissipate the hum. How you get to those 72 hours is completely up to you and how many sessions you are willing to tolerate that hum. We recommend and personally do a 72 hour straight burn in because we can but if you need to do 36 separate 2 hour burn in sessions it will result in the same dissipation.
Hello, I bought one last year, and it came with the manual.
It’s just a simple booklet all chinese with all the Darkvoice products on it , so for me it’s useless.
I purchased a Tung-Sol 6SN7GTB and it has left channel hum. I get no hum from the stock tubes. I have had the Tung-Sol in the DV336SE as specified in the post for about 48 hours.
I would like to know what to expect in terms of the left channel hum. Should it be gradually dissipating? Or, will it just completely stop after about 72 hours?
It should be gone after the burn in, or at least greatly reduced.
The hum is gone. Mad Science.
I’m glad I found this post! I just bought the Tung-Sol 6SN7GTB and a used GE version too and both hum in my Darkvoice 336se. The new Tung-Sol more so. I’ll try the burn in method but I’m enjoying it too much at the moment even with the stock tubes (they’re not bad, IMO).
Note to others, I got a NOS 6AS7 (ended up being a Sylvania) and a NOS 6080 (GE). Both work great but I haven’t tried different combos yet. I tried them all to make sure they worked.
Update. This burn-in technique worked like a charm for the Tung-Sol 6SN7GTB and NOS GE 6SN7 I bought.
I am guessing the answer to this is an obvious “yes,” but does this extended burn-in time have an impact on the lifespan of the tube? After 72 hours my Tung-Sol still has a pretty noticeable hum on the left side, so I’m letting it go longer. But at this point it has been left on for so long! Isn’t this kind of a lot of hours of simulated “use”? Does this method (no power tube, no sound) have less of an impact on tube lifespan than if there were any sound input/output?
Also, does swapping the power tube introduce any hum? I take it from your post that it’s a bit less safe to burn in both tubes at the same time since the power tube produces so much more heat. So that leads me to believe that if you are supposed to also burn in the power tube, it could be a bigger problem.
This is a super helpful post! Thanks for any other help you can provide!
Update: I’m coming up on 144 hours of burn in and the left side hum has lessened, but is still present. I guess I’ll let it go for a bit longer, but I’m starting to think that no amount of burn in will completely eliminate the hum. That’s a bit disappointing to me. Do I have a bum tube? Or a bum Darkvoice? Or my expectations were too high about eliminating the hum in the first place?
Hi, if after proper thorough burn-in time does not resolve hum, the issue is either not the tube at all, but hum from the amp with any 6SN7 tube installed, or a Tung-Sol 6SN7 tube that coincidentally has an issue of it’s own. However because you notice it is still reducing, I do think it’s only a matter of time before it’s perfect.
The few days of hours used for burn-in are minuscule in the total lifespan of the tubes.
Technically speaking, it is the opinion of many folks that the amp’s design is really to blame. Simply installing coupling/bypass caps prevents this hum every time, with any 6SN7. Look into the capacitor mod if you want to avoid this.
Thanks for the response and the encouragement to not worry too much about the burn in time.
I’m happy to report that after nearly 192 hours the hum is completely gone from the left side. It was a real marathon, but it worked! Thanks again!
It took me around 100 hours but my tung-sol tube is silent.
Do you know if with the SHUGUANG TREASURE CV181-Z the story is the same?
With the 6AS7 power tube removed and the 6SN7 in place… if I turn the unit on with the power plugged into the wall.. I get no power/ lights… is the burning in process still occurring?
Are you referring to the blue LED? If yes, I’ve not seen/heard of that happening before so I wonder how your amp is wired differently than standard. However it may not matter if the 6SN7 is still lighting up. You should see the heaters glowing the tube warming.
Isn’t the back 6AS7 tube called the power tube for a reason? I was under the impression that if the power tube is not plugged in then there is no power? Am I missing something? Thanks.
It’s the output tube, which often is called a power tube. Removing it for the 72hours of burn-in is what prevents the amp from over-heating. You can burn it in with all tubes installed, it’s just slower as you’ll need to power down more often to keep the heat under control. If your particular amp is behaving differently than any other DV336SE we’ve ever seen or heard of, I suggest you reach out to the manufacturer for details.
I got my Darkvoice a couple of days ago and it’s already driving me crazy. Don’t get me wrong, I love the sound of it, the fact that it’s completely silent (no hums or hisses between tracks), etc., etc. BUT, I get a static-y noise in the left channel, even with volume turned all the way down and no input cable attached. The noise is pretty random, in terms of “shape” (for lack of a better word) and volume; it gets louder and then disappears completely for a few minutes, just to be back again the next moment. It sounds somewhat similar to the wind blowing on a microphone. Or, more or less, like the crackling sound you get from a dirty vinyl record. Just like some kind of static charge accumulates somewhere in the circuits and then gets discharged into the headphones. I don’t know, does this make any sense? And, by the way, it’s still there one or two seconds after I turn the amp off.
From the sounds of things you may have a bad 6SN7. We would suggest swapping that tube out and see what happens.
Thanks for your reply, Sandra. I’ll replace the tube and see what happens. I’ll be back.
Just replaced the power tube with a NOS Svetlana 6AS7G. The “snapin’, cracklin’, and poppin'” noise (as DarkDrummer so accurately described it in his post) is completely gone! The sound appears to be a little more detailed, but slightly less bassy. So far, so good.
I’m having some issues that I cannot figure out. I’ve had my Darkvoice for a little over 3 weeks now and I immediately swapped the stock tubes with a Tung-Sol 6SN7 and an RCA 6AS7G. At first I had the left channel hum I’ve heard so much about (and boy was it loud depending on the headphone). I did a 72 hour burn in and the hum had lessened quite a bit, almost low enough that I can tolerate it. Almost enough. So I burned it in two days ago for another 24 hours and boom, no more hum (96 hrs!)
Only problem is, I now have a light scratching static noise coming out of the right channel, even when nothing is attached. It’s a quiet noise (almost akin to plugging in a 3.5mm from one powered source to another), but it easily interferes with my quieter tracks. I’m not sure what is causing this and I’m also unsure if it was always there to begin with. I even tried swapping to the original power tube but it also has the same static. Is this something I’ll have to look into a new power tube for or do you guys think its a solder problem as I’ve read elsewhere?
Most simple way to confirm if the noise is from a new tube or from the amplifier will be to install all of your original tubes and then confirm whether or not the noise is present. If it is, the amp is to blame. If it is noise free, you know it’s from the new 6SN7.
Sadly it looks like its the 6SN7 and I’m well beyond my return date (not that I mind keeping it, looks cool). Time to try another one. Thanks Jon!
Please can you tell me if I need to have my headphones connected during the 72 hours burn in.
No headphones required. Just uninstall the power tube before you start the burn-in.
Bought the cv-181T Natural Sound for my Darkvoice 336se. There is a very loud buzzing/ringing noise, mostly on the right side. Does this require the 72 hour burn in?
This article applies to all 6SN7 tubes used in this amplifier. Give the instructions a try and if that doesn’t work it could be something else worth giving us a call about.