Little Dot Tube Amps: Vacuum Tube Rolling Guide
Aug 26, 2014 at 4:08 PM Post #7,291 of 13,435
40 what?
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 One NOS RCA 6SN7 GTB for $45 no thanks.So much for a NOS tubes LOL.
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Aug 27, 2014 at 3:54 AM Post #7,295 of 13,435
My C3g adapters arrived today:



Wow, they sound beautiful with the 1578s! Too early for a full review, but I have no doubt this combination could be an 'end game' for many. Full rich sound, with great bass and not much compromise in other areas.
 
Aug 27, 2014 at 4:00 AM Post #7,296 of 13,435
My three 'new gear' CDs are Miles Davis KoB, Sinead O'Conner Am I not ur grl, and Eric Clapton Undrugged. All slightly different sounds and each beautiful in its own rights. I know each better than any other recordings. Right now, with the tubes mentioned above, KoB sounds sublime (again!).

BTW, if you like classic female old school big band jazz/blues vocals, look up the Sinead album.
 
Aug 27, 2014 at 4:32 AM Post #7,297 of 13,435
My MK III will never see a $100+ tube not even $30/Tube............:D  
The most i spend for my CHATHAM 6AS7G's are $20/tube and some that i got from auctions it works out to $10.50/tube i've got seven tubes from that auction.
Not even the CRACK or the S.E.X. will see that amount for a tube.


I have bought a LOT of tubes super cheap. I spent a long time poaching auctions on great 6SN7s. If you read some of the 6SN7 threads, you can learn to recognise re-branded great tubes and pick them off for < $15.

eBay never sleeps, but it does sometimes 'look the other way'. I have poached great tubes listed as 6SNGT (missing 7) that don't show up in the straight forward search and I have found amazing tubes in grab bag lots from estate sales. Getting a bargain is great fun. I have a pair of Ken Rad VT 231 s on the way for less than $10 each!! But there are some tubes that are more difficult to get a bargain on. It is very unlikely you will ever get real 1578s on the cheap.... Or Tung Sol BGRPs.

Happy hunting
 
Aug 27, 2014 at 4:46 AM Post #7,298 of 13,435
For example:




The first pic is from a lot of 5 6SN7s I bought for $35. These two tubes are both black glass NUs, that sell for $70 to $90 a pair. All were reported as 'test good'. A great deal.

The second two are a Ken Rad VT231 and a grey glass Sylvania VT231 I picked up from an estate auction for $15. A great deal... And fun finding a match for each on the cheap!

It is important for everyone to know that very good deals are out there. Perhaps not all NOS tubes, but still testing 'good'....
 
Aug 27, 2014 at 9:40 AM Post #7,299 of 13,435
My C3g adapters arrived today:



Wow, they sound beautiful with the 1578s! Too early for a full review, but I have no doubt this combination could be an 'end game' for many. Full rich sound, with great bass and not much compromise in other areas.

 
Hi MMMan.
 
I am so glad you like those C3Gs...just you wait 'til they have 30+ hours on them - you'll be blown away! Would have loved to see how those 1578s compare to my GEC 6AS7Gs, but at those prices I shall have to pass lol!! Shall just continue to take the risk, unless I chicken out and do (or have done for me) the suggested mods to make the 6AS7Gs safer to use
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Enjoy!!
 
Aug 27, 2014 at 11:03 AM Post #7,300 of 13,435
Hi,
 
After listening to the Sylvania 7963 sub miniature tube I have come to the conclusion that it needs some 70 hours of burn in to bring out the full potential. At that stage the bass became much more articulated and stronger. Tried it with my pair of Chatham 6080 tubes (nothing untoward happened) but somehow there was too much bass and it sounded boomy. The synergy wasn't there.
 
With the pair of RCA 6SN7GTB (top heater wire) the synergy is there, and I can revel in the clarity and detail of the entire musical spectrum + great musicality and sound stage. There is a multilayered presentation of the music, and on obscure 20s recordings i can follow and pick out individual instruments with much greater ease than before. It is hard to tear yourself away from the listening - it is so beautiful with superb sound in all ranges.
 
In addition, these tubes are easy to drive for the MKIII and no external power supplies are needed. Don't know what the "cryo treatment" my fans add, but the amp is literally cold to touch, and the power tubes are barely warm.
 
Happy tube rolling! (BTW, the entire tube complement cost me less than $20)
 
Aug 27, 2014 at 3:29 PM Post #7,301 of 13,435
  Hi,
 
After listening to the Sylvania 7963 sub miniature tube I have come to the conclusion that it needs some 70 hours of burn in to bring out the full potential. At that stage the bass became much more articulated and stronger. Tried it with my pair of Chatham 6080 tubes (nothing untoward happened) but somehow there was too much bass and it sounded boomy. The synergy wasn't there.
 
With the pair of RCA 6SN7GTB (top heater wire) the synergy is there, and I can revel in the clarity and detail of the entire musical spectrum + great musicality and sound stage. There is a multilayered presentation of the music, and on obscure 20s recordings i can follow and pick out individual instruments with much greater ease than before. It is hard to tear yourself away from the listening - it is so beautiful with superb sound in all ranges.
 
In addition, these tubes are easy to drive for the MKIII and no external power supplies are needed. Don't know what the "cryo treatment" my fans add, but the amp is literally cold to touch, and the power tubes are barely warm.
 
Happy tube rolling! (BTW, the entire tube complement cost me less than $20)

 
WELL DONE, mordy! Sounds like you're getting the same kind of magic that I am - but for much cheaper lol! Can't be bad
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. And no need for external "gubbins"...even better!!
 
That heavy, boomy bass is why I stuck with the 6AS7Gs....the Chathams and especially the (expensive!) GECs
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Out of interest, what differences do you find between your 7963s and the 5687s?
 
Aug 27, 2014 at 4:36 PM Post #7,302 of 13,435
.......But there are some tubes that are more difficult to get a bargain on. It is very unlikely you will ever get real 1578s on the cheap.... Or Tung Sol BGRPs.

 
If you are patient, even good deals on TS BGRPs can be found. Many are rebranded and some sellers don't know what they have. Recently, I saw one branded RCA in a RCA box. The seller thought it was an RCA and had it listed for $15, "Buy It Now". I tried, but must have just missed it, as it was already gone....   :frowning2:  lol.
 
I currently have three, two of which are branded Emerson, and I also have a 12SN7. And I didn't pay all that much for any of them.
 
At least in my experience, patience will always be rewarded. :)
 
Aug 27, 2014 at 5:09 PM Post #7,304 of 13,435
Hi hypnos 1,
 
Today the fabled 6AS7 Chatham tubes arrived with a price tag just slightly over my self imposed limit. I assume that the tubes were made in Dec 1958. First impression is excellent: unusually coherent and wide sound stage and great detail. The bass has more slam and the treble more sizzle than the RCA 6SN7GTB tubes but nothing of the boominess I heard with the 6080s in combination with 7963.
 


Here is an explanation of this experimental setup: In the center are the two Chatham tubes. To the right is a 15A voltage regulator powering the heaters. In the background left is the humble 7963 tube mounted on a breadboard with wires going to the Vector adapters in the drivers seats. On top right and left are two computer fans that draw away air from the amp.
The voltage regulator is using a very sophisticated mounting plate of premium scrap wood from a floor molding that is attached with two rubber bands to the transformer housing. In order to aid in cooling two Chinese chopsticks are inserted behind this mounting plate. The metal rod between the chopsticks belongs to a temperature probe to monitor the transformer housing temperature. The blue and yellow strips on the left are two plastic tie-ties to hold the smaller fan in place.
 
The amp is mounted on three 1980s aluminum cone footers (not seen in picture) to lower vibrational effects and aid in cooling. The chassis temperature is monitored by the human touch by inserting the hand under the the amp to feel the temperature. (At the present slightly warm.) I also use olfaction to monitor the health of the amp.
 
For some reason it appears to me that these tubes run cooler than the 6080s, although they are said to draw 0.84A each.
 
Re the question of comparing the 7963 to the 5687 I need to do a head to head comparison and then figure out which combination sounds best (Chatham vs Chatham or 6AS7 vs 6080) to pronounce a winner or a draw. But first I need to convince myself that the 5687 sounds the same on a 6V or 12V diet.
 
Below is a close-up of the coke bottle style Chatham 6AS7G tube as well as another coke bottle style tube. The latter has a liquid but dark and fizzy presentation, but more about that at another time.....
 


PS. After this picture was taken the real Coke bottle took revenge and pushed the imitation coke bottle off the desk smashing it into oblivion. At least it wasn't a GEC tube, and I still have a pair left, but now I know how it feels......
 
Aug 27, 2014 at 9:15 PM Post #7,305 of 13,435
A few pages ago, i offered my 12ax7 adapter but no one seems interested, so i was going to roll some 12ax7 next month and wanted to ask you if there is something i have to look out for to not harm my beloved LDMKIII?
 
EDIT: Mikelap just told me to look up the list on following page

http://www.head-fi.org/t/563884/little-dot-tube-amps-vacuum-tube-rolling-guide/4875#post_10229116
 

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