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Dark Voice 339 - Page 87

post #1291 of 2404

Quick question.  Which is better--buying a used RCA tube that tests as new or buying from Tube Center, where I know its NOS but I'm not guaranteed a brand?

 

EDIT:  I really wanted RCA, but didn't want to pay NOS prices so I went ahead and bought a matched pair.  I called the guy's shop and he said that he found them in an abandoned industry machine that was powered by hundreds of them so each wasn't passing much current. He claimed they all tested as NOS despite being used and he was able to match pairs out of most of them. He said he was getting to the end of them but had yet to receive a complaint.

 

He also had a 100% Ebay rating and said he'd take them back if I'm not happy.  In the future I'll probably stick to Tube Center, but it seemed like a good deal (famous last words).


Edited by BackwardPawn - 1/11/13 at 6:34pm
post #1292 of 2404

Another quick question.  My Russian tubes arrived.  They were shipped out of a tube warehouse in Moscow.  My parents are afraid they may have been scavenged from the Chernobyl exclusion zone and want me to get rid of them.  I think that anything coming into the country from that region would be scanned for radiation by customs.  I realize I paid $10 a tube so its no big loss if I throw them out, but don't really see a reason to.  Any thoughts?

post #1293 of 2404
Quote:
Originally Posted by BackwardPawn View Post

Another quick question.  My Russian tubes arrived.  They were shipped out of a tube warehouse in Moscow.  My parents are afraid they may have been scavenged from the Chernobyl exclusion zone and want me to get rid of them.  I think that anything coming into the country from that region would be scanned for radiation by customs.  I realize I paid $10 a tube so its no big loss if I throw them out, but don't really see a reason to.  Any thoughts?

 

I never heard that one before :)

I hope mine aren't radioactive :D

post #1294 of 2404
Quote:
Originally Posted by Ultrainferno View Post

 

I never heard that one before :)

I hope mine aren't radioactive :D

I called my uncle's neighbor who knows these kinds of things.  He said that there's radiation detection equipment setup in most customs stations.  If they were radioactive, he think it would have been stopped somewhere along the way.  

 

He then told me to have my uncle take them to work and test them on a geiger counter or I'd never hear the end of it from my mother :)  He knows my family too well.

 

On another note, he said that he thinks he has my grandfather's old tube tester.  I'm curious to see if the RCA tubes I bought will actually test as new.


Edited by BackwardPawn - 1/11/13 at 6:27pm
post #1295 of 2404
Quote:
Originally Posted by Ultrainferno View Post

6SJ7GT is a direct replacement of the 5693 right? So it can be used in a stock 339 without adapter?
I'm pretty sure this is the case but I'm just double checking wink.gif
I use both the rca 5693 reds as the tungsols 6sj7gt mesh plates..both are compatable..at least in my 337 biggrin.gif
post #1296 of 2404

I'm really starting to think that there is a problem with these EF80s, unless I'm burning them in wrong.  I left them running for about 8 hours yesterday.  Let it cool for a while, then ran it another few hours.  Today I've run it for at least another five.  The good news is that they don't make noise when the volume pots are at zero anymore.  The problem now is that the left channel makes a moderate humming noise and the right channel makes a loud buzzing noise when I give it any volume.  The music is audible, but the buzz is killing my ears (and my headphones?)

 

Whats the correct way to burn these in?  I've left them with the volume pots at zero.  Do I need to give it some juice and let the headphones me the ugly noise in order for the tubes to settle, or are these bad and I should just write them off as a bad purchase and try again?  Thanks.

post #1297 of 2404
Quote:
Originally Posted by BackwardPawn View Post

I'm really starting to think that there is a problem with these EF80s, unless I'm burning them in wrong.  I left them running for about 8 hours yesterday.  Let it cool for a while, then ran it another few hours.  Today I've run it for at least another five.  The good news is that they don't make noise when the volume pots are at zero anymore.  The problem now is that the left channel makes a moderate humming noise and the right channel makes a loud buzzing noise when I give it any volume.  The music is audible, but the buzz is killing my ears (and my headphones?)

 

Whats the correct way to burn these in?  I've left them with the volume pots at zero.  Do I need to give it some juice and let the headphones me the ugly noise in order for the tubes to settle, or are these bad and I should just write them off as a bad purchase and try again?  Thanks.

It seems like you got defective pair which is prone to buzz/hum or otherwise the adapters interference and making the noise and need to be adjusted.
To be sure try to swap them and see if something has changed, check whether they are sensitive to touch if yes, it's looks like the issue with the adapters, the same happened to me some while ago with EF800TFK hummed like hell.
To adjust the adapter you will need open it, (lifted up the top ring which is glued to the metal base) with sharp tool, then you will see a twisted bundle of cables, so with the headphones over head, Be careful! gently twist/turn the top plate of the adapter few millimeters left or right to make the hum less affected until disappear for good, do the same with the other adapter.

 

Hope this helps a little.


Edited by WALL-E - 1/13/13 at 3:45pm
post #1298 of 2404

I actually bought 4 that were supposed to be NOS.  I swapped the sides but didn't swap the adapters to see if thats where the worse hum was coming from.  On the bright side, my Russian tubes sound much better than stock.  I was considering buying another cheap pair of EF80s to try.  Should I adjust the adapters first and see if that's where the buzz is?  It honestly sounds like ground hum.  Alternatively, are there any decent tubes that would fit without an adapter?

post #1299 of 2404

I've loosened the ring on the top.  I'm giving the amp a few minutes to cool down.  Luckily, no glue is holding the adapter together.  I pulling it apart to I can see where the wires come together.  I try the one side first and see if I can get it to stop buzzing.

post #1300 of 2404

My EF80 adapters are ungrounded.  If I hold a screwdriver to the adapter, the buzzing clears up!  I guess I'll have to email Yuking and ask him for new ones. :(

post #1301 of 2404
Quote:
Originally Posted by WALL-E View Post

It seems like you got defective pair which is prone to buzz/hum or otherwise the adapters interference and making the noise and need to be adjusted.
To be sure try to swap them and see if something has changed, check whether they are sensitive to touch if yes, it's looks like the issue with the adapters, the same happened to me some while ago with EF800TFK hummed like hell.
To adjust the adapter you will need open it, (lifted up the top ring which is glued to the metal base) with sharp tool, then you will see a twisted bundle of cables, so with the headphones over head, Be careful! gently twist/turn the top plate of the adapter few millimeters left or right to make the hum less affected until disappear for good, do the same with the other adapter.

 

Hope this helps a little.

You actually helped quite a bit.  Both adapters have grounding issues.  One adapter I was able to shift until it was partially grounded, the other adapter won't work at all...even if I get the ground buzz to stop, the volume control won't work properly.  I removed that tube as soon as I realized the issue it was causing.  I've put the stock input tubes back on for now and have asked Yuking if he could send me a pair of working adapters.  Hopefully it doesn't take too long.  Thanks for your help.

 

EDIT:  I've opened up the adapters and see where the ground wire is and how its supposed to be threaded through the screw.  On yours, you were probably able to move it a few millimeters and get screw to touch the wire.  On mine, I was able to get one working for the most part.  There was still a little ground hum during silence, so it wasn't perfect, but the tube sounded ok. 

The other is completely messed up.

 

I was able to ground the other adapter on my screwdriver, but the volume control was messed up while using it.  I couldn't ground it by moving it, though.  At that point I gave up and figured I'd have Yuking send me new adapters.  If for some reason I can't get the adapters, I have some almost new Telefunken EF80s I could sell.  The silk screening has come off two of them, but they are Telefunken.  Yuking's been pretty good to me, though, so I'm sure he'll be able to get the adapters to me.  As a last resort I'd get some 5698s, but I'd rather be able to use the telefunkens.


Edited by BackwardPawn - 1/14/13 at 6:35am
post #1302 of 2404

 

Hi I attached the picture of my adapter as u see the metal barrel is not directly grounded to the ground of amplifier probably to avoid the ground loops.The blue thick cable soldered on inside the barrel is twisted along with the rest and connected to the upper tube socked like on attached picture, the blue wire with a black band, so the metal housing of the adapter working like a shield for the wires if u know what I mean.

By adjusting the adapters I meant squeeze (tight turn) or loosen the bundle of wires by turn to the left or to the right the metal top part of adapter, which have significant effect in my case on the reduction of hum/noise.

 

The decent tubes which do not require adapter are RCA 5693 and my favorite mesh-shield 6SJ7GT,


Edited by WALL-E - 1/14/13 at 2:11pm
post #1303 of 2404
Quote:
Originally Posted by WALL-E View Post

 

Hi I attached the picture of my adapter as u see the metal barrel is not directly grounded to the ground of amplifier probably to avoid the ground loops.The blue thick cable soldered on inside the barrel is twisted along with the rest and connected to the upper tube socked like on attached picture, the blue wire with a black band, so the metal housing of the adapter working like a shield for the wires if u know what I mean.

By adjusting the adapters I meant squeeze (tight turn) or loosen the bundle of wires by turn to the left or to the right the metal top part of adapter, which have significant effect in my case on the reduction of hum/noise.

 

The decent tubes which do not require adapter are RCA 5693 and my favorite mesh-shield 6SJ7GT,

I managed to fix one of the adapters using your method.  The other adapter is beyond usable.  All I get is static and noise.  I hope I didn't hurt my drivers trying to fix that one.  They're probably ok, though.  I guess I go back to the stock ones for now.  Hopefully Yuking gets back to me quickly, but I understand he has a lot going on.

post #1304 of 2404

Which of those two that don't need adapters are best with bright phones like Beyers?  I leaning toward trying the 6SJ7GT based on your recommendation, just want to make sure its not a bright tube.  Also, how do they compare to the EF80s?  The guy at the tube store I called asking if he sold adapters (they didn't) recommended against using adapters.  If I can get a good pair of adapters, I'd still really like to hear the EF80 and decide for myself, but may end up taking his advice and just using octagonal mounted tubes if the adapters continue to be a problem.

 

Honestly, the stock input tubes and the Russian tubes I'm using now sound great--so I can only imagine I'll be in heaven when I finally get a set of input tubes and try out the RCA power tubes that just came today.


Edited by BackwardPawn - 1/14/13 at 7:55pm
post #1305 of 2404

Does anyone have any experience with RCA 6SJ7WGT Mesh plate tubes?

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