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Little Dot Tube Amps: Vacuum Tube Rolling Guide - Page 402

post #6016 of 10502
Quote:
Originally Posted by Gerrrsh View Post

I recently was gifted a Little Dot I. It's got two tubes (the front pair) that are blown and I need to replace them. The front pair are 1T4 RCA tubes and the back 4 are 3A4 RCA tubes. Also, can someone please explain why it has two different voltages? What difference does it make? Is it just an audio thing or is it something to do with power?

Edit: I'm very new to this level of audiophila. Before I was just a simple headphone geek.
Now there is a vintage piece of gear, I guess it is hard to find tubes for and it runs rather hot. You might want to consider getting a newer amplifier unless you can find a source for the tubes.
beerchug.gif

www.head-fi.org/t/503046/old-possibly-original-little-dot
post #6017 of 10502
Well I stand corrected... biggrin.gif
http://www.ebay.com/sch/i.html?_trksid=p2050601.m570.l1313&_nkw=1T4+tube&_sacat=0&_from=R40
post #6018 of 10502

Hi Joe Doe,

 

As you mention, each terminal block has two screw posts; it does not matter which one you use. The proof that everything is connected properly is getting sound from both channels.

 

Please be careful in touching the bare solder/wires - some voltages can go up to over 155V. Good luck!

post #6019 of 10502

relying on gibosi and hypnos1 judgment i just ordered some adapters(c3g to 6ak5) from china.I also could get some used C3g with these measurements:

 

1 x Telefunken = 10,5 mA,

1 x Siemens = 10,5 mA,

2 x Siemens = 12,5 mA

 

they were measured with "Funke W19" and "good" starts at 6,5mA with the Funke.

 

do you think it'll be worth it buying those used tubes?

post #6020 of 10502

Hi superdux,

 

What prices are they asking? The Funke W19 is supposed to be one of the best testers. Are these tubes from JACMusic?

 

Are the tubes C3g or C3gS?


Edited by mordy - 5/4/14 at 11:14am
post #6021 of 10502
Quote:
Originally Posted by superdux View Post
 

relying on gibosi and hypnos1 judgment i just ordered some adapters(c3g to 6ak5) from china.I also could get some used C3g with these measurements:

 

1 x Telefunken = 10,5 mA,

1 x Siemens = 10,5 mA,

2 x Siemens = 12,5 mA

 

they were measured with "Funke W19" and "good" starts at 6,5mA with the Funke.

 

do you think it'll be worth it buying those used tubes?

 

Again, these are 10,000 hour tubes. They should have lots of life yet in them. Enjoy. :)

post #6022 of 10502

Hi Gibosi,

 

Could you elaborate on double triodes that you feel are equal to but different from the C3g tubes? The cheapest I could found a pair of the C3g tubes was $70 incl shipping.

post #6023 of 10502
Quote:
Originally Posted by mordy View Post
 

Are the tubes C3g or C3gS?

 

From this site:

 

http://www.radiomuseum.org/tubes/tube_c3gs.html

 

"In case the final factory-tests of a C3g revealed a transconductance equal or higher than 105% of the nominal value ( 14000 µmhos), these tubes were marked with the suffix /s."

 

So the C3gs appears to be nothing more than a C3g that was measured at the factory and found to have a slightly higher transconductance value than the design spec. In my opinion it is probably not worth spending a lot more for these......

post #6024 of 10502
Quote:
Originally Posted by mordy View Post
 

Hi superdux,

 

What prices are they asking? The Funke W19 is supposed to be one of the best testers. Are these tubes from JACMusic?

 

Are the tubes C3g or C3gS?


hi this is an auction(not from JACMusic) and i'm planning on not going to high with my bid cos of "onion leather" in my wallet.But i'd be willing to forward 2 of these if i win the auction for auctioning price and postage.They are C3g.

 

EDIT: sorry folks, i've found someone from Europe who is willing to take the 2 tubes from me.


Edited by superdux - 5/7/14 at 5:43am
post #6025 of 10502
Quote:
Originally Posted by mordy View Post
 

Hi Gibosi,

 

Could you elaborate on double triodes that you feel are equal to but different from the C3g tubes? The cheapest I could found a pair of the C3g tubes was $70 incl shipping.

 

Well, of course this is all very subjective... My current favorites are Sylvania 6SN7W, both short and tall bottle, Fivre 6SN7GT, National Union gray glass 6SN7GT, Heerlen- or Eindhoven-made E80CC and 1975 Voskhod 6N23P. If you can find them, the Voskhods are probably the cheapest of these, but in my experience, when purchasing from Ukraine and Russia, I never really know what I am going to get before they arrive.... I believe you have a '74? I find it to sound virtually the same as the '75.

 

I am very poor at comparing tubes... I don't have the discipline or the ears for it.... But I can say that in my mind, these are all top-tier tubes, they are all very, very close, with only very subtle differences. One might be a bit more forward, one might be a little more warm, one might have a bit more bass detail, and so on.... I could be happy with any of them long term.

post #6026 of 10502

And I thought I should remind those who have a 9-pin breadboard socket and Vectors, that it is easy to roll C3g's too. Just be very sure you do not have a tube plugged into your 9-pin socket at the same time! :)

 

post #6027 of 10502
Quote:
Originally Posted by gibosi View Post

And I thought I should remind those who have a 9-pin breadboard socket and Vectors, that it is easy to roll C3g's too. Just be very sure you do not have a tube plugged into your 9-pin socket at the same time! smily_headphones1.gif



Good to know!
post #6028 of 10502

Hi Gibosi,

 

Thanks for your answer - made me feel better. Yes, I have four 1974 6N23P tubes that cost me $4 each shipped. I had trouble communicating to the seller the year I wanted until I used Google translate.

 

Now I am listening to another bargain tube, the GE 1954 12SL7GT which cost me less than $2 each in a lot of four tubes (3 GEs and and a Coke Bottle 6AS7 RCA). Nice, brassy rich sound.

 

 

I have been looking for the 12SX7 tube (a premium version of the 12SN7) that Nic Rhodes recommended, but can only find it for around $20, so I took a chance on this tube. Seems that GE made fine tubes in the 50's, and this one does not disappoint. Somehow I have the preconceived idea that silver plate does not sound good (based on some 6AK5 tubes with silver plate), but this one is sounding very good.


Edited by mordy - 5/4/14 at 1:41pm
post #6029 of 10502

If I used two loctal breadboards with the Vectors, could I skip the adapters? This would shave off half the price of the $60 adapters.

post #6030 of 10502
Quote:
Originally Posted by mordy View Post
 

If I used two loctal breadboards with the Vectors, could I skip the adapters? This would shave off half the price of the $60 adapters.

 

You sure can! I was thinking about doing this, but I just don't have enough room on my desk. With a couple of loctal breadboard sockets, you can connect G3 to the Cathode and G2 to the Plate using the compression terminal blocks and then you will have two nice pentode-strapped triodes. :)

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