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Little Dot Tube Amps: Vacuum Tube Rolling Guide - Page 393

post #5881 of 10509
Quote:
Originally Posted by gibosi View Post
 

 

Actually, it is possible to do this with only one "lot of degradation". :) 

 

7N7 to 6CG7 adapter:

 

http://www.ebay.com/itm/two-Adapters-7N7-plug-adapters-6CG7-ECC88-tubes-amplifier-SUB-/250751485734?pt=Vintage_Electronics_R2&hash=item3a61f40726

 

And for those of you who do not want to mess with loctals, the late 1940's to early 1950's small-bottle chrome-top Sylvania 6SN7GT and GTA sound very similar to the 7N7.

 

Hi again gibosi.

 

Just popped back to correct my previous post - said mordy, not mab - and found your post...certainly much better than two piggy-backed, but $37 each PLUS postage?...OUCH!!...Will stick to my blood, sweat and tears!...

 

Cheers.

post #5882 of 10509
Quote:
Originally Posted by i luvmusic 2 View Post
 

how do you read the date on tubes?

 

For the small-bottle chrome-top Sylvania 6SN7GT and GTA (and other Sylvania tubes):

 

326 = 1953 week 26

 

 

Top etch codes:

 

D= April, 2 = 1952 (And R = Replacement - that is, not OEM issue)

 

 

Edit: Added top etch codes and fixed typos


Edited by gibosi - 4/18/14 at 7:40am
post #5883 of 10509
Quote:
Originally Posted by hypnos1 View Post
 

 

Hi again gibosi.

 

Just popped back to correct my previous post - said mordy, not mab - and found your post...certainly much better than two piggy-backed, but $37 each PLUS postage?...OUCH!!...Will stick to my blood, sweat and tears!...

 

Cheers.

 

Actually, $37 for a pair plus $13 for shipping (to the States), so still not cheap. :(

post #5884 of 10509

My tubes marking on the base are AL and on top of tubes F4B and F3B these are Sylvania Chrome top no number markings anywhere on or around  the tubes.So F=June 4=1954  and B=? is these right?


Edited by i luvmusic 2 - 4/18/14 at 7:52am
post #5885 of 10509
Quote:
Originally Posted by i luvmusic 2 View Post
 

My tubes marking on the base are AL and on top of tubes F4B and F3B these are Sylvania Chrome top no number markings anywhere on or around  the tubes.

 

F4B = June 1954 and F3B = June 1953

 

Also, you will see these small-bottle chrome-top Sylvania 6SN7GT and GTA with short bases and tall bases, still the same tube, same sound. :)

 

 

post #5886 of 10509

You can make a dapter for 8 pin to 9 pin using a copper fitting(reducer) 1'' to 3/4''. or 3/4'' to 1/2 for 9 pin to 7 pin.

post #5887 of 10509

What about EL34 as power tubes?

post #5888 of 10509
Quote:
Originally Posted by mab1376 View Post

What about EL34 as power tubes?
The EL34 is a pentode, you would need 4 of them strapped as triodes and probably would not work in our LD configuration. biggrin.gif
post #5889 of 10509
Quote:
Originally Posted by gibosi View Post
 

 

Actually, $37 for a pair plus $13 for shipping (to the States), so still not cheap. :(

 

Thanks gibosi...I should look more closely. But yes, not cheap...then again, if you can find the 7N7 for the right price you could be on to a winner!

 

A few more hours on the 7N7/Psvane combo and still WOW...I cannot believe it...veeery interesting!

post #5890 of 10509

Hi hypnos 1,

 

Firstly, I decided to try an all Russian all star lineup and use two 6P23N tubes for power tubes, and one for a driver. This worked quite well, and the bass became firmer and better controlled, without a feeling of hollowness. Nevertheless, real slam and attack in the bass is missing, but all-in-all a nice combination.

 

Then I read your impressions of mixing two different power tubes and getting a synthesis of the best of them both. Sounds interesting; let's try it. So I swapped out one 6P23N for my trusty Hoffman (nee RCA) top heater wire 6SN7.

 

Well, I listen through speakers and not headphones, and unfortunately I did not get any synthesis of the sound, but two distinct halves, right and left. The Hoffman side sounded full bodied and coherent with a fat round bass, and the Russki side sounded thin, akin to the difference in general between the 6N6P-IR tubes compared to the RCA 6SN7 octals when used as power tubes.

 

In conclusion, this did not work for me, but it taught me that power tubes could make such a difference that I could clearly hear the difference, similar to hearing the differences between different sets of driver tubes.

 

Now I am listening to the 6N23P as a driver with the RCA 6SN7 as power tubes. This is quite a good combination - the sound is open and forward with great detail and soundstage, except for a peculiar brightness bump in the upper midrange - we'll see if it gets better by time. The bass is very strong with great impact and slam; the mid bass is outstanding with a propensity to unlock the full bass potential of old 20's 78's (and everything else for that matter).

 

Funny that the other way around (6N23P power and octal driver) it is only OK, but this way with 6N23P as driver and power octals it is quite good.

 

About the upper midrange bump - I have four tubes, so I'll may try another one if it does not go away.

post #5891 of 10509

Just received Little Dot MK III and wanted to try some new tubes. I just don't understand if i have to change all 4 tybes or just the two small ones?

*n00b*

post #5892 of 10509
Quote:
Originally Posted by BbOO View Post
 

Just received Little Dot MK III and wanted to try some new tubes. I just don't understand if i have to change all 4 tybes or just the two small ones?

*n00b*

The 2 Tubes in the back are the POWER tubes and  the 2 in front are the DRIVER tubes . You can roll a few types of power tubes but there are  a lot more driver tubes to try out . The 6n6pir Russian power tubes are nice and cheap at around$13.00 each and are popular here's link http://www.ebay.com/itm/161171325915?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT                                                                                                                                                                                                                                                          For driver tubes alot of guys here like yugo's 6HM5 here's a link if interested offer $5.00 each  http://www.ebay.com/itm/300879467071?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT. For a list of  the  tubes you can try out go to page 77 of this thread post #1154. and remember not all tubes on that page are plug &play so best thing is to start reading around page 40 for the tubes on page 77 up to about page 200 + infos on power tubes on page 191


Edited by MIKELAP - 4/19/14 at 8:13am
post #5893 of 10509
Quote:
Originally Posted by mordy View Post
 

Hi hypnos 1,

 

Firstly, I decided to try an all Russian all star lineup and use two 6P23N tubes for power tubes, and one for a driver. This worked quite well, and the bass became firmer and better controlled, without a feeling of hollowness. Nevertheless, real slam and attack in the bass is missing, but all-in-all a nice combination.

 

Then I read your impressions of mixing two different power tubes and getting a synthesis of the best of them both. Sounds interesting; let's try it. So I swapped out one 6P23N for my trusty Hoffman (nee RCA) top heater wire 6SN7.

 

Well, I listen through speakers and not headphones, and unfortunately I did not get any synthesis of the sound, but two distinct halves, right and left. The Hoffman side sounded full bodied and coherent with a fat round bass, and the Russki side sounded thin, akin to the difference in general between the 6N6P-IR tubes compared to the RCA 6SN7 octals when used as power tubes.

 

In conclusion, this did not work for me, but it taught me that power tubes could make such a difference that I could clearly hear the difference, similar to hearing the differences between different sets of driver tubes.

 

Now I am listening to the 6N23P as a driver with the RCA 6SN7 as power tubes. This is quite a good combination - the sound is open and forward with great detail and soundstage, except for a peculiar brightness bump in the upper midrange - we'll see if it gets better by time. The bass is very strong with great impact and slam; the mid bass is outstanding with a propensity to unlock the full bass potential of old 20's 78's (and everything else for that matter).

 

Funny that the other way around (6N23P power and octal driver) it is only OK, but this way with 6N23P as driver and power octals it is quite good.

 

About the upper midrange bump - I have four tubes, so I'll may try another one if it does not go away.

 

Yes mordy, this "mix and match" of power tubes is certainly going to be very "hit and miss" - with a good heap of luck thrown in!. And obviously is a no-go with tubes that are too dissimilar. But if one has a good variety to play with I am sure it could just prove a worthwhile (if not interesting!) experiment...nothing to lose lol..

 

As for my pairing of Psvane CV181- T II and short-bottle chrome-dome 7N7, with 20hrs burn-in for the adapter (the 7N7 being a used tube) I don't seem to be getting any mismatch whatsoever - the exact opposite in fact...my first WOW impressions have now been confirmed. I think I must have lucked-out BIG time, lol. :p Mind you, it could just be down to my right ear not being quite up to scratch compared to the left. So, just as astigmatism is remedied with lenses, the ear equivalent can apparently be remedied with tubes...methinks I just might have stumbled upon a very useful revelation indeed! And I'm sure I am not the only one with such a defect... Whatever, I personally seem to have struck gold...another reason for me NOT to continue with my mad quest to try the 6AS7 (when they arrive). But curiosity is killing this cat!

 

Anyway mordy, keep playing around with different combinations - I'm sure you will find the 'magic' one soon...but you might just have to do a gibosi and try a lot more tubes yet in your search - all in a good cause, of course!!

 

Happy rolling :wink_face:

post #5894 of 10509
Quote:
Originally Posted by mordy View Post
 

Then I read your impressions of mixing two different power tubes and getting a synthesis of the best of them both. Sounds interesting; let's try it. So I swapped out one 6P23N for my trusty Hoffman (nee RCA) top heater wire 6SN7.

 

Well, I listen through speakers and not headphones, and unfortunately I did not get any synthesis of the sound, but two distinct halves, right and left. The Hoffman side sounded full bodied and coherent with a fat round bass, and the Russki side sounded thin, akin to the difference in general between the 6N6P-IR tubes compared to the RCA 6SN7 octals when used as power tubes.

 

In conclusion, this did not work for me, but it taught me that power tubes could make such a difference that I could clearly hear the difference, similar to hearing the differences between different sets of driver tubes.

 

I think the 6SN7 and 6N32P are much too different to use in this way. Putting an RCA 6SN7 on one side and a Sylvania 6SN7 on the other might give you a better idea of what Hypnos1 is hearing with his 7N7, which is just a short-bottle Sylvania 6SN7 with a different base, and Psvane CV181, which is also just a 6SN7.

post #5895 of 10509
I was chatting with a serious tube guy the other night and telling him about the rolling thread here... The first question he asked was WHY? Rolling tubes without the knowledge of how they operate and without doing the calculations and adjustments to the circuitry is basically pointless.

I told him we were looking for the best sounding tubes for the amp and he corrected me by saying that without doing any of the calculations and modifications we were just finding the "Least worst compatible tubes"...

Much truth to that and something to think about.
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