Darkvoice 336i & 336SE Tuberolling PartII
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maheeinfy

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Last night i rolled a bunch of tubes on DV

Concluded that any noise/hum i heard is due to driver tube on the front.

Stock chinese - hum in left channel
GE 6sn7gtb - both my tubes were decent sounding but still put out mild audible hum in both left&right channels
Sylvania 6sn7gtb - crunch/arcing noise in one channel at times, But no hum
TungSol russian 6sb7gtb reissue - both of them sounded like car enginee was turned on. Loud audible noise into left&right channels
TungSol USA 6sn7gtb - almost silent. Very mild hum and these sound great. Best of the bunch
 
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spacequeen7

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Last night i rolled a bunch of tubes on DV

Concluded that any noise/hum i heard is due to driver tube on the front.

Stock chinese - hum in left channel
GE 6sn7gtb - both my tubes were decent sounding but still put out mild audible hum in both left&right channels
Sylvania 6sn7gtb - crunch/arcing noise in one channel at times, But no hum
TungSol russian 6sb7gtb reissue - both of them sounded like car enginee was turned on. Loud audible noise into left&right channels
TungSol USA 6sn7gtb - almost silent. Very mild hum and these sound great. Best of the bunch
Try to wiggle your RCA cables on the back of DV or source
Edit ; "hum" could be related to ground-loop also
 
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Oskari

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Anyway, enough rambling and back story. I've got a two part question to ask if you don't mind. I'm close to picking up a dirt cheap RCA 6SN7GT but can't work out the code on it. See pic below



Does the 35 represent the third week of 1950?
Also, is this a grey glass 6SN7? I've read info on one of the tube sites that said the 'grey' starts just up from the bottom and end just below the top.

Lastly, the reason its going dirt cheap is that its untested. I know that's probably a bit of a no no, but could it hurt the amp or is the worst that can happen that it's simply a dud?
Looks grey to me! That's 1950 and week 35. Yes, it can be a bit risky, a short inside the tube, for example. Not a huge risk, perhaps, but it is there.
 
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Jamie G

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Thanks for the reply Oskari, one day I'll get my head around these manufacturer codes! So ended up grabbing it for 4gbp, had to do it for that price, sadly tubes seem to be in quite short supply in the UK so you have to grab them while you can.

I'm gonna have to try it though right? Especially with all the love that grey glass RCA's are given on here! Anything I can do to minimise the risk?

Thanks again
 
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Oskari

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I'm gonna have to try it though right? Especially with all the love that grey glass RCA's are given on here! Anything I can do to minimise the risk?
Cut the power fast if you notice anything untoward! :smiley_cat:
 
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Gallic Dweller

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A lot of obsessing with different tubes, fact is even really expensive commercial gear can benefit from modding. There are threads here on Headfi and on other forums that show really simple mods that transform the DV. The DV has issues that I'm surprised that the Chinese didn't put right years ago - restricted volume use is one, hum is another, disconnecting the pre-amp out - how many use it? yields immediate sonic benefits, transformer voltage issues for both USA/EU, signal wiring - this is a really simple mod, something that is mostly ignored which is crazy since it is the foundation of what is actually heard.

Do, or get done if you don't feel able to some some of these mods - then shell out for better/different tubes. Jim Spec has been banging on about 6F8G tubes, so have I - these tubes are the older brother of the 6SN7 and for those who have both, most would say that the FGs are a touch ahead, I agree with that.

It's crazy to put the power tube ahead of the signal tube. Sadly for those who are late to the party the Tung Sol Round Plates are stand-outs, nowadays neither the 6SN7 or 6F8G come cheap - as Morgan Jones said -"if only I could use the 6SN7 in a phono stage.
 
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Jamie G

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Cut the power fast if you notice anything untoward! :smiley_cat:
Ha ha, I'll be standing by fire extinguisher in hand! :thumbsup:If anything were to be wrong with it, it'd go wrong pretty quick right?
 
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Jamie G

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Cant be worse than this
[/QUOTE]
Oooh pretty :astonished: He must've known that was going to happen right?...if not, stop filming and flick the switch man!!

Or perhaps he was transfixed by the light show like me
 
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maheeinfy

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Cant be worse than this
Oooh pretty :astonished: He must've known that was going to happen right?...if not, stop filming and flick the switch man!!

Or perhaps he was transfixed by the light show like me[/QUOTE]

No one wants the fire works stopped :L3000:
 
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maheeinfy

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Try to wiggle your RCA cables on the back of DV or source
Edit ; "hum" could be related to ground-loop also
Any reason for wiggling the rca? RCA connectors on DV are extra tight so the connection is solid

I dont think in my case its the ground loop as on some tubes hum is almost non existant
 
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spacequeen7

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Any reason for wiggling the rca? RCA connectors on DV are extra tight so the connection is solid

I dont think in my case its the ground loop as on some tubes hum is almost non existant
Crank that pot to around 2 o'clock if there is no noticeable hum or distortion then you ground-loop free ,this "thing" is like magnifying glass ,I had to get battery bank for my D50 and R2R11 is no go
DV's pre output seams to be the culprit (there was mod mention online but the technical aspect was removed from the original thread ) also any loose RCA connection tends to transfer all that unwanted noise
Some of my tubes seams to be noise free then after some tube-rolling they will become slightly micro-phonic so I assume driver socket is not the best quality or tubes have mind of their own ,tube rolling can be PITA sometimes ,especially on DV
Cheers
 
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Jamie G

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Anyone know anything about these?


IMG_20180722_014226.png

I'm assuming the 'Victor' branding means it came from one of their radios?

Anything special or is it just a regular old 6as7g?
 
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