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Little Dot Tube Amps: Vacuum Tube Rolling Guide - Page 538

post #8056 of 8068
Quote:
Originally Posted by mab1376 View Post
 

 

It may indicate a leak in the glass. Its what happened to one of my 6AV6 when i clipped the pin and it cracked the glass.

 

Not saying its definitely the issue, but a possibility. 

Thats what i was thinking at first with these tubes , it looked suspicious .                                                                                                                                                                                                                                                                                                                                                   CREATOR: gd-jpeg v1.0 (using IJG JPEG v80), quality = 95

post #8057 of 8068

Hi TD,

 

I agree with you that your system looks miles better than mine. However, I don't let anybody into my listening room/office/junk collection, and my wife hates the music I am listening to, so WAF is not a factor here.

 

Aesthetics don't bother me, and the sound of  my system is superb. Waiting to see if the C3g will be an upgrade.....

post #8058 of 8068
Quote:
Originally Posted by TrollDragon View Post
 

 

Way too much crazy action going on there... I'll stick with the basics as it has a better WAF.

 

 

Hey TD...does this not have a fair degree of WAF?....

 

 

...Not to mention a sound way better...and well within your capabilities, mon ami!  :D

post #8059 of 8068
Quote:
Originally Posted by hypnos1 View Post
 

 

Hey TD...does this not have a fair degree of WAF?....

 

 

Nice Tubes! (Click to show)

 

 

...Not to mention a sound way better...and well within your capabilities, mon ami!  :D

Yes indeed WAF is strong with this one...

post #8060 of 8068
Quote:
Originally Posted by mordy View Post
 

Hi TD,

 

I agree with you that your system looks miles better than mine. However, I don't let anybody into my listening room/office/junk collection, and my wife hates the music I am listening to, so WAF is not a factor here.

 

Aesthetics don't bother me, and the sound of  my system is superb. Waiting to see if the C3g will be an upgrade.....

All is good then, my amp sits out front and center so I have to keep the self contained part up.

 

I was asked how long those "Big Ugly Headphones" were going to stay up there... :eek: 

 

Sacrilege I tell you, Sacrilege.

post #8061 of 8068
Quote:
Originally Posted by TrollDragon View Post
 

All is good then, my amp sits out front and center so I have to keep the self contained part up.

 

I was asked how long those "Big Ugly Headphones" were going to stay up there... :eek: 

 

Sacrilege I tell you, Sacrilege.

 

I feel for you, TD...some people in a household just have NO SOUL!!  :(

post #8062 of 8068
Quote:
Originally Posted by MIKELAP View Post
 
Quote:
Originally Posted by JazzVinyl View Post


I am using 6SN7's as powers with that adapter on my LD MK IV and I really like them, a lot...

Hoping you will make me a pair of C3g to 6Ak5 adapters, Hint hint hint... :-)

.

Waiting for parts to make first pair the problem  will be to make them as short as possible need a one piece body for that with the right dimension for the sockets or else a 2 piece adapter with all the sockets installed  ready to go will be about 13/4¨ tall +the tube maybe a bit less . with one piece adapter it could possibly be as short as 1 inch tall thats the goal may be will need to have them machined will see when i get parts  Heres a ruff 2 piece construction i started   with regular octal socket the loctal socket seems to be thinner  than the octal socket .

 

                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           

 You can get a 1'' to 1/2'' reducer  then cut the 1''part if you need to.What you have there is 3/4'' to 1/2''  and 1'' to 3/4'',8 pins fits in 1'' coupling and 7 pins fits in 1/2'' coupling 9 pins fits on 3/4'' coupling.If you are Having a hard time getting the 1'' to 1/2'' PM me.


Edited by i luvmusic 2 - Yesterday at 2:23 pm
post #8063 of 8068

6SN7M

 

http://www.ebay.com/itm/PAIR-2-6SN7M-RCA-NOS-BRASILIA-MOST-UNIQUE-6SN7-VERY-RARE-LIMITED-SUPPLY-/311146512544?

 
It is my understanding that these are simply RCA 6CG7s stuffed into metal cans....
post #8064 of 8068
So many ingenious ideas!
Thanks for all the effort to share them, mordy !

beerchug.gif

Quote:
Originally Posted by mordy View Post

Hi BGRoberts,

My LD amp sits with three aluminum cones on a MDF shelf on an equipment rack. The rack itself sits with spikes on a hardwood floor. Each shelf sits on four tabs within a metal frame. Each tab has a round marble between the tab and the shelf. All this is supposed to eliminate unwanted vibrations. Don't know what works best individually or in combination, but I do not have any problems with microphonics. What my set up is lacking in looks is made up by practicality.





Here is the equipment rack with various contents. The blue, yellow and white plastic ties hold the two fans in place. On the top left is a temperature probe whose tip touches the transformer housing. On the shelf underneath is the Little Dot MKIII standing on three footers. On the transformer housing an 15A voltage regulator is attached with two rubber bands. The two white pieces behind it are wooden chopsticks to make a space between the voltage regulator mounting plate and the transformer housing to allow for better air circulation and cooling.
To the left of the amp on the shelf is a mounting board for two voltage regulators that supply power to one of the fans and the driver tube, seen on the bottom suspended by wires to the two Vector adapters (less hum).





Here the shelf is lifted up to show the arrangement with a marble to cancel out vibrations.





Here are the 80's aluminum cones attached with generic bluetack to the bottom of the LD amp.



This is the 12V 4" fan mounted above the amp.




Here is a close up of the temperature probe. Actual temperature of the transformer housing today with the amp in operation is 78F. Room temperature is 67F. On a hot day with a room temperature of around 76F with A/C on the temperature may go up to 89F.







Here is the second fan, also mounted above the amp. It is a 12V 3" computer fan from a busted power supply. It was chosen because it is quiet. Rather than blowing air on the amp, both fans draw the hot air away from the amp. Under the fan are seen two 6080WA Sylvania 2.5A power tubes. How do these octal tubes fit into the 9pin sockets on the LD?





Since the octal to 9pin adapters are too wide to fit inside the decorative rings on the LD MKIII, a 9pin socket extender is needed. The little red strip marks the orientation of the adapter for easy insertion. The octal adapter goes into the extender, and the tube - you guessed it - goes into the octal adapter.
Since the 6080 tubes use much more current than the amp can provide, an external 15A voltage regulator is connected to the heaters of the tubes. On the left of the extender you can see a wire coming out. A hole was drilled in the bakelite of the extender. The heater pins were desoldered and removed (the extender comes apart easily with one screw) and the wires soldered onto the pin tabs inside the extender. If you use 6SN7/6SL7 octal tubes as power tubes no external power supply is necessary.
The 15A voltage regulator is powered by a 430W computer power supply. I found that that a beefier power supply resulted in better sound.





This is the15A voltage regulator. The smaller voltage regulators can be bought with voltage readouts, but for some reason these come without - you will need a simple voltage meter to set the voltage to 6.3V using a little set screw on the voltage regulator. For some reason the voltage reading taken at the tube pins always is lower than at the voltage regulator itself, but may differ a little between different tubes. Usually, with the 6080s, I have to set the voltage to around 7V to get 6.3V at the tube itself. The large heat sinks never get warm in use.

What else is there to describe? The fans run on 12V, and I used whatever I had on hand. One is powered by a 12V wall wart from an old portable phone, the other shares the 12V PC power supply with the heaters for the power tubes. The 12V driver tube uses an old laptop 19.8V power supply via a voltage regulator.

This set up is very flexible, and I can use all kinds of driver/power tubes that use different voltages - 6V, 7V, 8V, 12V - no problem.

It's been a long journey, littered with tubes relegated to the dust pile, but very rewarding.....
post #8065 of 8068
Quote:
Originally Posted by TrollDragon View Post
The 274b is a rectifier, not a 6SN7... biggrin.gif
http://www.sophiaelectric.com/pages/se/274b.htm
Quote:
Originally Posted by gibosi View Post

Mine have the same packaging - C3g-S, but the black casing says C3g. Evidently this is normal. I have read that the C3g-s also have "Post" printed on the side, and the standard C3g do not. This is true of the two pairs I have one C3g-s and the other C3g, but I do not know if it is true for all.

And the link you posted is to allow a 5687 to be plugged into your power sockets. If you want to use 6SN7's, you will need an adapter similar to this one:

http://www.ebay.com/itm/1pc-6SN7-6H8C-6N8P-CV1988-B65-VT231-TO-ECC88-6922-6DJ8-6N6-6N11-tube-adapter-/201083508552?

So, I had two Oopses. :wink: Looking actually at the names of the socket adapter links, makes it quite obvious. Just got a bit confused by the new tubes available for the LD. Thanks for the corrections. 0474.png

it

I will look for the "s" on my C3g. Brilliant, you found it. This weekend, I am away from my kit, so I will check Monday.

 

Mordy, Thank you for that Link before to the C3g history, very interesting.

post #8066 of 8068
Quote:
Originally Posted by Oskari View Post
 
Quote:
Originally Posted by bbmiller View Post
 

Are there any databases which lets you search for tubes by pin arrangement? Do pin arrangements of vacuum tubes have names that can be search for in any way? On the Internet? On a page itself if you search for the recognizable pin arrangement name, say in certain very good datasheets?

 

There are the EIA base codes like 7BD for the 6AK5. See

 

 

If you click the "same base" button, you'll get a list of all the 7BD-based types in the database.

 

TDSL PE lets you search in multiple ways, but this one you need to install on your computer and I'm not sure whether it runs on current Windows systems.

 

OK that software you recommended runs on my Windows 7 computer just fine. Thanks!


Edited by bbmiller - Today at 9:26 pm
post #8067 of 8068

Hi G,

 

Probably you already saw this comment from 2011 about the metal tubes:

 

"comment about late production Brazilian made RCA 6SN7M after I found out that someone is currently selling them on eBay for $88 (!) a pair. A few years ago I got a handful of them for nothing in a dumpster store. I understood they are not true 6SN7 after a friend of mine told me he had opened the metal can to find out that there was miniature 6FQ7A/6CG7 inside. Wires had been spot welded to make for the pin conversion. While it looked like a neatly done factory job, I doubt the metal can around the tube will help heat exchange, so it should probably run a little hotter than if it was at open air. Electrically, the interchangeability seems very good, as long as one consider that the smaller plates of the 6FQ7A/6CG7 should not withstand the very same power dissipation.

Now I wonder how these odd late Brazilian 6SN7M got reach to the States. Mine are still on the store. Cheers for all,

Flavio, from Brazil."

 

The pair you referenced went for $148 - excellent marketing! You can pick up 6CG7 tubes for a couple of dollars. I have some sold by Sears - Satisfaction Guaranteed or your money back.....

post #8068 of 8068

Hi BGRoberts,

 

Thanks for your comment. I forgot to point out that except for soldering four wires inside the 9pin extenders everything else goes together with a small screwdriver.

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