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Little Dot Tube Amps: Vacuum Tube Rolling Guide - Page 428

post #6406 of 10486
Quote:
Originally Posted by mordy View Post
 

Hi philiptw,

 

Unless your Voskhod tube turned white inside instead of the silver coating I do not believe that it is dead. I once had a 6N6P tube that I wrote off for dead, but did not throw it away. A year later I gently scraped the pins with a pocket knife blade, pushed it in and out of the socket a few times, and it worked perfectly again. Seems a little oxidation caused it to malfunction.

 

Take any kind a knife blade that is small, hobby knife, pen knife etc, and just scrape each pin gently from different angles. Take a look if you can see oxidation on the pins, and if so, especially scrape those parts.

 

Let me know when you revive the tube...

 

Good luck!

 

Thanks Mordy :-)

 

Unfortunately the getters are white powdery so I am pretty sure of its demise.. there's also a crack at the bottom of the tube..

I wanted to open it up to see the structure but seeing as platinum can be a toxic chemical I decided to not open it up.

 

See the photo below for the Voskhod's #beautifuldeath (any GoT fans here?) :rolleyes:

 


Edited by philiptw - 6/6/14 at 9:55am
post #6407 of 10486

Here is a little update on using the 6080 2.5A tube as a power tube. At this point I am waiting for a second 5A voltage regulator from China, but couldn't resist trying out one channel with a 6080. Picked a 6080 RCA that only earned a so-so rating as driver tube (my notes say 'murky") just in case Something Would Happen.

 

In order to use it in the LD MKIII it is first plugged into an octal to 9 pin adapter; then into a 9 pin extender to fit inside the ring surrounding the socket. This extender was taken apart and pins #4 and 5 were de-soldered and removed and replaced with two wires going to the external voltage regulator. This necessitated drilling a hole in the side of the extender socket to allow for the two wires to exit neatly.

 

The tube complement features an all star set up of the 1957 subminiature 6832 as driver (using the built in LD power supply), a 1957 Tung Sol 6SN7GTB as power tube for the left channel (LD powered) and the 1962 RCA 6080 as power tube for the right channel, using the external 5A PS.

 

A trial run indicated that the amp was getting warm. After an hour it was quite warm, but  not too hot to touch. Out of caution I installed a fan to cool off the amp. Here are a couple of pics:

 

Here is a close up of the extender showing the two wires coming out and teeth #4&5 missing. Used a little piece of white sticker to mark off the right pins and a little piece of blue to line up with the indentation on the top so that it goes together correctly.

 

 

Here is the fan assembly. The fan comes from a an old PC power supply and was picked for being fairly quiet. The power supply is a 12V wall wart that once powered a router. The plastic fasteners are used to tie the fan to my equipment rack in such a way that the fan sucks away the hot air instead of blowing directly on the amp. If you touch the 6080 you could burn yourself (ouch, just did), but the fan lowers the temperature of the amp chassis significantly.

 

Here is the triple dual triode (tongue twister?) line-up. The 6832 is swinging to the music like a buoy on the ocean. (Finally got the nail polish insulation but have yet to decide on fire engine red or turquoise blue.)

 

The sound is fabulous with a glorious bass and treble (and this is with the worst sounding 6080 I have!). Will have to try to better sounding 6080s and the coke bottle 6AS7 RCA as well. Meanwhile I am just enjoying the sound. Did I mention that this set-up is very quiet as well?

 

Here I have to quote hypnos 1 on the achievements of the members on this forum:

 

Unorthodox?...AGREE . But I would also venture to add : resourceful; pioneering; fascinating; educational; rewarding, BRAVE...and not a little MAD! But isn't this precisely what so often results in the greatest quantum leaps in any endeavor? (And, no doubt, been a source of a little amusement for the 'purists', lol!).

 

Whatever, hopefully what has been achieved is proving to be of great benefit to those LD owners who are now enjoying a level of sound from their lowly machines way beyond what may have ever been thought possible (well, it is for me anyways!). And hopefully also for those yet to come...

 

Maybe alternating red and blue? LOL......
post #6408 of 10486

Hi philiptw,

 

You made the correct diagnosis; the tube died from lack of vacuum - sorry. The good news is that there are better choices....

post #6409 of 10486

Since most of us tried or continue using 6AS7/6080 tubes as Power tubes what if we use these tubes for both driver and power, what would be the out come?Maybe a big bang.:biggrin:


Edited by i luvmusic 2 - 6/6/14 at 1:01pm
post #6410 of 10486

As long as you have the required external PS there is no problem in running a 6AS7/6080 as a driver. With an amplification factor of 2 the volume has to be turned up higher. You just have to experiment and see which tube/tube combination sounds the best.

 

Having tried such tubes as drivers my impression is that the subminiature 6832 sounds better as a driver, whereas the 6832 cannot compete with the 6080 as a power tube for lack of power in the bass region. The way I envision it in my mind is that the power tubes contribute significantly to the bass and rhythmic foundation of the sound presentation. Having the 6AS7/6080 as a driver might be a little "heavy handed", but I may be wrong. Haven't tried it yet.

post #6411 of 10486

Sorry i mean can we use 3 6AS7/6080 tubes all at once for LD MK III/IV or would it be too much for LD circuits?

post #6412 of 10486

Oh schiit i'am going to kick my self on the head i accidentally dropped one of my G.T.C. 6AS7G i just received these tubes few minutes ago.:(.

 

post #6413 of 10486
Quote:
Originally Posted by i luvmusic 2 View Post
 

 

Warning: Spoiler! (Click to show)

Oh schiit i'am going to kick my self on the head i accidentally dropped one of my G.T.C. 6AS7G i just received these tubes few minutes ago.:(.

 

 

 

RIP... I feel your pain..

post #6414 of 10486

Yup that's what i get for not being careful got too excited because the G.T.C. is a mystery tube. 

post #6415 of 10486
Quote:
Originally Posted by i luvmusic 2 View Post
 

Sorry i mean can we use 3 6AS7/6080 tubes all at once for LD MK III/IV or would it be too much for LD circuits?

 

The driver and power circuits are separate and the heaters are powered externally, so it should work. But I don't know that anyone has tried it yet.

post #6416 of 10486
Quote:
Originally Posted by i luvmusic 2 View Post
 

Yup that's what i get for not being careful got too excited because the G.T.C. is a mystery tube. 

 

I am pretty sure your GTC was manufactured by Tung Sol / Chatham.....

post #6417 of 10486
Quote:
Originally Posted by gibosi View Post
 

 

I am pretty sure your GTC was manufactured by Tung Sol / Chatham.....

Yeah who ever makes it it sound nice. 

post #6418 of 10486
Quote:
Originally Posted by gibosi View Post
 

 

The driver and power circuits are separate and the heaters are powered externally, so it should work. But I don't know that anyone has tried it yet.

You know what since the GTC is on the driver's socket i will turn off the PS and the amp and let it cool down so i can change the 2 RCA Power tubes with 2 SYLVANIA 6080 wish my LD MK III luck. 

post #6419 of 10486
Quote:
Originally Posted by gibosi View Post
 

 

I am pretty sure your GTC was manufactured by Tung Sol / Chatham.....

 

I though the Tung-Sol/Chatham tubes all had top getters and earlier examples had grey glass bottoms and new examples had clear bottoms?

post #6420 of 10486

Just wanna say wow a bit more power in bass would be perfect setup.

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