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Little Dot Tube Amps: Vacuum Tube Rolling Guide - Page 396

post #5926 of 10502

Sylvania and RCA should also be very affordable still, Tung Sol carry  a massive premium nowdays.

post #5927 of 10502

Hi Gibosi and hypnos 1,

 

Have been thinking about how to pair different power tubes to get a synergistic effect. My first try resulted in hearing two distinct halves of the music using a 6DJ8 and 6SN7 type tube. Acting upon Gibosi's suggestion to use similar (sounding) tubes I got better results.

 

At this point my thinking is that you need to match two similar tubes with complementing characteristics ( detailed/analytical + musical as an example). Could also be that they have to play similarly loud to get the right effect.

 

Right now I am trying two 6SN7 tubes, a RCA top heater wire and a Japanese tube. The RCA is more musical and the Japanese more detailed. I get a coherent sound stage that sounds very nice, but I need more time with this setup to finalize my impressions. (Something is bothering me, but I can't put my finger on it.)

 

The driver is a 1952 Philco/Sylvania 6BL7 1.5A tube. This tube has an amplification factor of 15 compared to the 6BX7 with an amplification factor of 10. Otherwise these two tubes sound similar with great clarity and punch. In the words of Nic Rhodes, these are cracking/awesome tubes and available at real bargain prices. IMHO I would recommend trying these tubes before spending megabucks on hyped up boutique tubes.

 

Now, could I use a combination of one 1.5A tube + one 0.9A tube as power tubes in the LD MKII? As I understand it, the transformer can handle up to 2.5A.

 

Before I try it, I would like to hear if this is safe - thanks.

post #5928 of 10502

So a few weeks with the C3gS/6SN7 combo and i'm still loving it, an absolute perfect match with the HD650's

 

It also sounds amazing with my TT setup as a preamp playing through my Klipsch Forte speakers.

 

However my T70's still have a slight buzz when not playing music, its completely inaudible when playing music so i'm suspecting due to the extremely high sensitivity of those headphones that i'm picking up some noise from the AC heaters.

 

Either way still a great setup and highly recommended.

 

I am still curious ho some other tube variants would work as power tubes, i'm very anxious to try some 6F8G or their cheaper variants, but i'll hold off for now until someone has some solid feedback on how they are.

post #5929 of 10502

Just took delivery of 2 pairs of driver tubes - a pair of Tung sol 6AJ5 and a pair of blue BTB EF95. The Tungsol had a fuller bodied sound with good bass impact whilst the blue BTBs had a leaner sound. Decided to get adventurous and mixed the tubes - 6AJ5 on the left and BTB on the right. Nice balance. Not entirely distinguishable differences in sound although bass lines where more rumbling, so to speak and mids/vocals were more pinpoint centric. Will listen a bit more and see if the sound changes (or my ears get accustomed to the sound)..

post #5930 of 10502
Quote:
Originally Posted by mordy View Post
 

Now, could I use a combination of one 1.5A tube + one 0.9A tube as power tubes in the LD MKII? As I understand it, the transformer can handle up to 2.5A.

 

Before I try it, I would like to hear if this is safe - thanks.

 

Mordy,

 

I think we have to assume that it is not safe to run a power tube that draws more than 1.25A. Even though the transformer appears to be good up to 2.5A, you cannot assume that the wiring supplying each tube can handle more than half of that. So, you might be able to get away with 1.5 amps, but then again, you might not....

post #5931 of 10502

Received a Sylvania subminiature 7963 double triode today.  I was very intrigued by this thread:

 

http://rockgrotto.proboards.com/thread/9798/sylvania-7963-best-e88cc-planet?page=1&scrollTo=134293

 

As you can see in this photo, it is indeed very small compared to a Voshkod 6N23P. So now I just have to figure out how to connect this little guy to my breadboard socket. lol :)

 

post #5932 of 10502
Quote:
Originally Posted by mordy View Post
 

Hi Gibosi and hypnos 1,

 

Have been thinking about how to pair different power tubes to get a synergistic effect. My first try resulted in hearing two distinct halves of the music using a 6DJ8 and 6SN7 type tube. Acting upon Gibosi's suggestion to use similar (sounding) tubes I got better results.

 

At this point my thinking is that you need to match two similar tubes with complementing characteristics ( detailed/analytical + musical as an example). Could also be that they have to play similarly loud to get the right effect.

 

 

 

Spot on mordy...that's precisely what I am getting with my Psvane/TS (Sylvania) 7N7 combo, and things just keep getting better ( I really can't get my head round what is happening!)...so good hunting!!

Quote:
Originally Posted by mab1376 View Post
 

So a few weeks with the C3gS/6SN7 combo and i'm still loving it, an absolute perfect match with the HD650's

 

It also sounds amazing with my TT setup as a preamp playing through my Klipsch Forte speakers.

 

However my T70's still have a slight buzz when not playing music, its completely inaudible when playing music so i'm suspecting due to the extremel

 

Real glad you're still loving the C3gSs...awesome indeed! And my 650s love 'em too....they were made for each other, that's for sure.

And partnered with my power combo, the  650s  are delivering a sound WAY beyond their relatively "cheap" price. Looks like synergy, synergy and more synergy! I'm now truly in sound heaven :tongue_smile:.

post #5933 of 10502
Quote:
Originally Posted by gibosi View Post
 

Received a Sylvania subminiature 7963 double triode today.  I was very intrigued by this thread:

 

http://rockgrotto.proboards.com/thread/9798/sylvania-7963-best-e88cc-planet?page=1&scrollTo=134293

 

As you can see in this photo, it is indeed very small compared to a Voshkod 6N23P. So now I just have to figure out how to connect this little guy to my breadboard socket. lol :)

 

You can solder 18 AWG solid copper wire then heatshrink all the terminals(individualy) and put a piece of round wood or plastic in the middle of all the terminals the same width with your socket on the breadboard then heatshrink the whole thing leaving enough copper to plug into the socket so now you have tube with built in adapter.You can used a ballpen tube cut to lenght then you wrapped electrical tape or heatshrink to get the width that you need.


Edited by i luvmusic 2 - 4/23/14 at 1:53pm
post #5934 of 10502

That's a great idea.... but I couldn't wait! lol :)

 

So I rewired the socket for this tube and then simply screwed the tube's wire leads into the compression blocks.... And it works! :)

 

I did find that it is very important to keep a fair amount of distance between the wires connecting the two plates in order to avoid what sounds like a strong ground hum.

 

First impression... It sounds great!  However, whether I think it is in fact the "best sounding E88CC / 6922 / 6DJ8 / ECC88 on planet Earth" as the reviewer on Rockgrotto wrote will take considerably more time to determine....

 

So my fellow tube rollers, add the Sylvania subminiature 7963 to the LD rolling list! 

 


Edited by gibosi - 4/23/14 at 7:09pm
post #5935 of 10502

Hi Gibosi,

 

The Sylvania 7963 is a frame grid tube. Here is a link to a post describing what a frame grid tube is - the writer obviously was not aware of the Sylvania 7963 tube:

 

http://www.head-fi.org/t/452721/fs-tesla-e83cc-gold-pin-nos-1-1-to-telefunken-ecc803s#post_6117913

 

Interesting....

post #5936 of 10502
Quote:
Originally Posted by mordy View Post

 

The Sylvania 7963 is a frame grid tube. Here is a link to a post describing what a frame grid tube is - the writer obviously was not aware of the Sylvania 7963 tube:

 

http://www.head-fi.org/t/452721/fs-tesla-e83cc-gold-pin-nos-1-1-to-telefunken-ecc803s#post_6117913

 

Interesting....

 

The ECC803S is considered by some as one of the "Holy Grail" tubes, very rare and evidently, very good. But it seems that the writer is only concerned with the ECC83 family of tubes. This overlooks the fact that the 6DJ8 is also a frame grid tube, as is the E80CC, the C3g, and the 7693. And there may well be others I don't know about.....

post #5937 of 10502

Recently so many great choices of tubes for the LD amps have become unearthed, and to me it is almost confusing. I do remember posts on this forum describing sub miniature dual triode tubes, and at one point I even dug up a list of possible choices. However, those octopus like wire leads scared me away since I did not know how to make an adapter. How do you know which lead is which? Probably a reference notch or some such.

 

Now Gibosi came up with such a simple idea: Simply screw in the leads into the breadboard compression blocks! Great!

 

Don't know how practical the following idea is, but are there little sleeves that could be put on regular tube pins and then an 18 gauge solid insulated wire could be crimped on to other end of the sleeve and inserted directly into the tube socket (or the breadboard)?

 

Anyhow, now that I discovered that I have a stash of the coveted frame grid 6DJ8 tubes I ought to give them more exposure.

 

Meanwhile I am trying out oldies but goodies. Two Sylvania 1950's 6SL7GTW tubes serve as power tubes, and another Sylvania 6BL7 serves as the driver. This 6BL7 tube is built like a tank with three micas, copper posts, and dual heaters top and bottom. It is labeled Automatic Radio.

 

Automatic Radio was a Boston radio manufacturer that existed from the 20's to 1957. It's most famous radio was the a miniature portable radio called Tom Thumb. Here is a tube version:

 

Tom_Thumb_Portable_Lawson.jpg

Apr08-Tom_Thumb-Fig2.jpg

 

Coming back to the SL-BL setup: The power tubes add an elegant lightness and delicious detail to the presentation. (Sorry, at the moment I can't think of better words to describe the sound)

 

Can't resist sharing these pictures of a Tesla radio and speaker:

 

tesla308u01.jpg

 

bakelite-radio.jpg

 

Good Night!

 

BTW, the US Tesla electric car company settled with the Chech Tesla electronic company about the trademark name; amount not disclosed.


Edited by mordy - 4/23/14 at 9:41pm
post #5938 of 10502
Quote:
Originally Posted by mordy View Post
 

.........I do remember posts on this forum describing sub miniature dual triode tubes, and at one point I even dug up a list of possible choices. However, those octopus like wire leads scared me away since I did not know how to make an adapter. How do you know which lead is which? Probably a reference notch or some such.

 

The 7963 has 8 wire-leads coming out of the base. There is a slightly larger gap between wire-lead #1 and wire-lead #8, similar to the larger gap between pin #1 and pin #9 on a 9-pin tube.

 

I have been thinking of putting this tube into an Octal base. It should be a simple matter to route the wires into the pins and solder them. It will certainly look strange, but it should work quite well.

 

$T2eC16VHJGIFFoo0GMS3BSV7,mlhfw~~60_1.JPG 

post #5939 of 10502

Will look no stranger than this one does...

:beerchug:

post #5940 of 10502

In lieu of the 5670/2c51 tube, has anybody tried the Russian 6N3P or the Chinese 6N3-J tubes?

 

Gibosi, do you have to cross wires inside the octal base to accommodate the 7963 tube? How do you insulate them and or reduce hum?


Edited by mordy - 4/24/14 at 10:43am
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