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Little Dot Tube Amps: Vacuum Tube Rolling Guide - Page 435

post #6511 of 10502
Quote:
Originally Posted by mordy View Post
 

Another update on the use of subminiature dual triode vacuum tubes with eight thin flexible leads in the LD amps. IMHO this approach of solderless connections should make it easy for anyone to try these type of tubes.

 

All you need is 1mm heat shrink tubing and 18 gauge solid copper wire + one 9 pin tube socket saver/extender and a breadboard.. A cigarette lighter can be used as a heat source for shrinking the tubing.

 

 

These little submini tubes are not visually appealing, but sound wise they can stand their own against anything we've tried, including the priciest icons. If you haven't heard one yet, give it a try. You may be in for a surprise.....

 

Mordy, a great tutorial! This is as easy as it gets! And now there is no excuse for anyone not to try these sub-miniatures, either the Raytheon 6832 (I also see Sylvania on eBay), or the Sylvania 7963.

 

IMHO the 7963 is as good as any tube I have. I would describe it as a "refined" version of the 1940's Sylvania 6SN7W. It has essentially the same sound signature - strong detailed bass, smooth silky mids and airy highs, but a bit more linear, faster, quieter.... and a lot cheaper! :)

post #6512 of 10502
Quote:
Originally Posted by mordy View Post
 

I'm sure many of you know the feeling. You turn on your beloved system, and somethin' is wrong. What, the left channel isn't working! What could the problem be? Speakers? PC? Bad connection? Did you finally kill the LD?

 

Well, u didn't listen to TD, and you did this crazy stuff and ran one channel on 12V and the other on 6V, and you used a 2.5A tube (with ext PS) where the max is 1.25A. How much does it cost to send it back to China? How do you contact LD? How long will it take to get it fixed? Could it be one of those pesky resistors (shudder)?Is it cheaper to buy a new one? MKIII or IV?

 

Perspiration, anxiety, worry. How can I listen to mediocre sound in the absence of the LD?

 

Well, let's see. Pull out all the external stuff, pull on all the wires, change all the tubes to OEM stuff. PC? - no, it works both channels. LD? Only the right channel. OK, I'll rewire the 6832 adapter; while I'm at it I'll add some some heat shrink insulation; seems less messy than turquoise nail polish - or red nail nail polish. Slap everything together. Perspiration. Doing a mental check: Can't remember any electronic acrid burnt smell, no poof or loud crackle. All three heaters light up. OK - turn on the sound. Sounds good, BUT ONLY THE RIGHT CHANNEL. Panic.

 

Well, it got to be something simple. Maybe. Didn't smell anything acrid, right. Of course, it must be that one of the E95 jumpers underneath worked itself loose or corroded. You just had to demonstrate that drum solo to one of your grand children, didn't you? Check - nyet; everything in place. Still NO LEFT CHANNEL. What's next? Check all the cables to the LD - everything OK. Calm down, take a few deep breaths, think about something else (can't). RELAX, RELAX.

 

To make a long story short: On the back of my 35 year old Sony amp is a slider switch that switches on and off an external equalizer loop. The LD is connected to this loop. Turns out that the switch corroded and killed the left channel. A few pushes back and forth cleared up everything. Hurray! Everything works! Need to get the super advanced hi tech super mods in place again - 12.6V 12SN7GT, 6.3V 6080, and the 6832 in it's new red clothes.

 

Relief...RELIEF....RELIEF

 

Another day in the life of a Little Dot owner.....

IMO the LD MK III can handle 2 6080/6AS7 Power Tubes and 1 6080/6AS7 Driver Tube i've tried this before  only i'am not comfortable running it for long due to heat issue.

post #6513 of 10502
I'm sorry ILM2 but that just doesn't equate. In your opinion you feel that the Little Dot can handle 3 power tubes but yet you won't run it in that configuration because the amplifier gets too hot...

Well then I guess it really doesn't handle it, does it?
post #6514 of 10502

Yes the amp start to gets warm around one hour of used i don't know if that is adequate enough for me to say it can handle it.If i'am only home i don't mind running it longer than that.I usually shut down the amp as soon as it gets warm the longest amount of time i used that set up 2 to 3 hours then i noticed it's hotter than usual.  

post #6515 of 10502
Personally I wouldn't risk it, heat is a killer and if the case is too hot to leave your hand on comfortably. Then there is an issue.

But I'm just the broken record...
So YMMV biggrin.gif
post #6516 of 10502

I thought about butchering the MK III and install a fan but then again  that's more work i just wait and build  a CRACK instead.:biggrin:

post #6517 of 10502

Does anyone here did a comparison between the 6080 and 6AS7G driver tubes?Thanks! 

post #6518 of 10502
Quote:
Originally Posted by tjw321 View Post

Thanks - will do. The shootout is (at least) half the fun, after all :beerchug: 

I do not know how many people have tried this, but I find the stock tubes take on an amazing improved audio quality once you have your little dot IV se on for more than four hours. I turned them on for hours before I want to start listening. Call me nuts but if you could include this in your shoot out and report here how the more than 4 hours on stock tubes compared with the rest of the ones in your shoot out I would be very appreciative.

post #6519 of 10502

Hi i luvmusic 2 and TD,

 

Regarding the heat generated by the 6080 tubes - there is plenty of it. At this time I am only running one 6080 (waiting for a second voltage regulator). In order to alleviate the (over?) heating problem, I installed a 4" fan from a discarded computer.

 

 

The fan runs off a 12V wall wart and is attached to my equipment rack with plastic ties in such a way that it draws the hot air away from the amp. With the ambient temperature in my room at 77 F the amp is barely warm to the touch after running for many hours (6-7 hours). Plan to turn on the A/C since it is too warm in the room now. Even with a second 6080 I anticipate that the heat will not be a problem. If it does become a problem I can always go to a bigger fan or a dual fan setup.

 

Meanwhile the Little Dot is singing the wonderful 6832 tune - perfect.....

post #6520 of 10502
Quote:
Originally Posted by mordy View Post
 

Hi i luvmusic 2 and TD,

 

Regarding the heat generated by the 6080 tubes - there is plenty of it. At this time I am only running one 6080 (waiting for a second voltage regulator). In order to alleviate the (over?) heating problem, I installed a 4" fan from a discarded computer.

 

 

The fan runs off a 12V wall wart and is attached to my equipment rack with plastic ties in such a way that it draws the hot air away from the amp. With the ambient temperature in my room at 77 F the amp is barely warm to the touch after running for many hours (6-7 hours). Plan to turn on the A/C since it is too warm in the room now. Even with a second 6080 I anticipate that the heat will not be a problem. If it does become a problem I can always go to a bigger fan or a dual fan setup.

 

Meanwhile the Little Dot is singing the wonderful 6832 tune - perfect.....

I like the setup(2 6080/6AS7 power tubes and 1 6080/6AS7 driver tube)i only run my amp for one hour or so due to heat but i may try your cooling fan method.THANKS!BTW the 6832 is amazing tube.:beerchug:

post #6521 of 10502
So I have this shaft with a sealed bearing in a pillow block, there is too much torque on the bearing, it gets hot and starts to squeal. I put a fan or two in front of the pillow block to blow away the heat, now the bearing is quiet...

Does this not seem like a problem?

The properly designed bearing would have a grease nipple on it to apply some of Titans oil as it is designed to take the load.

Which reminds me of an old gir...
Never Mind. tongue.gif
post #6522 of 10502

Hi bbmiller,

 

IMHO most tubes need a little warm up to sound the best. Usually I found that this period is a matter of minutes. Some larger octal tubes may need 30 minutes or more to sound their best. Have not noticed that tubes sound better after four hours.

 

There are other factors that come into play. All the above refers to tubes that have been burned in. In addition, many times your equipment sounds better late at night when a host of appliances, lights and electronic devices may be turned off, thus providing an electronic environment with less electric interference.

post #6523 of 10502

Hi i luvmusic 2,

 

I have very limited experience with the 6AS7 and 6080 tubes. When I tried the RCA 6AS7 as a driver I felt that it was very detailed and layered, allowing me to see into the sound stage and hear new things. The 6080 as a driver I found to have more punch in the bass and a little less detail and decided that overall it is well suited as a power tube. I have 7 6080 tubes, all various RCAs and one GE. The RCAs are from different years and have different construction details, and there are differences in the sound.


Edited by mordy - 6/10/14 at 6:38pm
post #6524 of 10502
Quote:
Originally Posted by bbmiller View Post
 
Quote:
Originally Posted by tjw321 View Post

Thanks - will do. The shootout is (at least) half the fun, after all :beerchug: 

I do not know how many people have tried this, but I find the stock tubes take on an amazing improved audio quality once you have your little dot IV se on for more than four hours. I turned them on for hours before I want to start listening. Call me nuts but if you could include this in your shoot out and report here how the more than 4 hours on stock tubes compared with the rest of the ones in your shoot out I would be very appreciative.

Quote:
Originally Posted by mordy View Post
 

Hi bbmiller,

 

IMHO most tubes need a little warm up to sound the best. Usually I found that this period is a matter of minutes. Some larger octal tubes may need 30 minutes or more to sound their best. Have not noticed that tubes sound better after four hours.

 

There are other factors that come into play. All the above refers to tubes that have been burned in. In addition, many times your equipment sounds better late at night when a host of appliances, lights and electronic devices may be turned off, thus providing an electronic environment with less electric interference.

well I would very much swear what I am hearing is real and not imagined or placebo in my opinion. Over four hours warming is the ticket for better sound with the original tubes in the little dot IV se.

post #6525 of 10502
Quote:
Originally Posted by mordy View Post
 

Hi i luvmusic 2,

 

I have very limited experience with the 6AS7 and 6080 tubes. When I tried the RCA 6AS7 as a driver I felt that it was very detailed and layered, allowing me to see into the sound stage and hear new things. The 6080 as a driver I found to have more punch in the bass and a little less detail and decided that overall it is well suited as a power tube. I have 7 6080 tubes, all various RCAs and one GE. The RCAs are from different years and have different construction details, and there are differences in the sound.

This is why asked because most of my 6AS7 have more detail than the 6080's except the G.T.C. 6AS7G this have more bass than the RCA's,GE's amd SYLVANIA's.Thanks!:beerchug:

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