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Little Dot Tube Amps: Vacuum Tube Rolling Guide - Page 392

post #5866 of 10504

Hi G,

 

Took up your challenge with the 6DJ8 family tubes as power tubes. Since I did not want to take a chance if anything untoward would happen, I picked some tubes from my stock that I don't use much; a near pair of 6BZ7 (GE and Sylvania) as power tubes, and a Russian 6N9C (6SL7 equivalent) as the driver.

 

 

The 6BZ7 is a 6.3V tube and draws 0.4A, so an easy load in the LD MKIII and a very similar load to the 6SL7 tubes. Took a deep breath and turned on the heaters on the Russki driver, than powered up the LD amp, waited 30 seconds for warm-up, then pushed the speaker button in. Sound! Music; sounds quite good. Seem to to have adequate power in my system. Also tried my AT ATH-AD700  headphones; they play very loud. Need more time to analyze the sound, but this combo definitively works.

 

Man, a new world of power tubes suddenly opened up! 6DJ8, 6BC8, 6BZ8, X155, 6BS8, 6BQ7 and the Russian 6N23P.

 

Popped in a (real) 1974 pair of the Voskhod 6N23P - sounds very good. The headphones need less volume than usual. Stay tuned.....

post #5867 of 10504
Quote:
Originally Posted by gibosi View Post

 

In the European system, the beginning "E" indicates 6V tubes. "F" indicates 12V tubes, but I don't know that I have ever seen a European tube beginning with "F"?

 

I don't think many F types existed.

 

post #5868 of 10504

http://www.stereophile.com/content/ear-v20-integrated-amplifier

 

Shows a ecc83 amp, not my cup of tea but popular!

post #5869 of 10504
Quote:
Originally Posted by mordy View Post
 

Hi G,

 

Took up your challenge with the 6DJ8 family tubes as power tubes. Since I did not want to take a chance if anything untoward would happen, I picked some tubes from my stock that I don't use much; a near pair of 6BZ7 (GE and Sylvania) as power tubes, and a Russian 6N9C (6SL7 equivalent) as the driver.

 

 

The 6BZ7 is a 6.3V tube and draws 0.4A, so an easy load in the LD MKIII and a very similar load to the 6SL7 tubes. Took a deep breath and turned on the heaters on the Russki driver, than powered up the LD amp, waited 30 seconds for warm-up, then pushed the speaker button in. Sound! Music; sounds quite good. Seem to to have adequate power in my system. Also tried my AT ATH-AD700  headphones; they play very loud. Need more time to analyze the sound, but this combo definitively works.

 

Man, a new world of power tubes suddenly opened up! 6DJ8, 6BC8, 6BZ8, X155, 6BS8, 6BQ7 and the Russian 6N23P.

 

Popped in a (real) 1974 pair of the Voskhod 6N23P - sounds very good. The headphones need less volume than usual. Stay tuned.....

 

Are the 12AX7 and 6DJ8 the same pinout?

 

It seems you didn't need any kind of adapter for this, would that be the same for the 12AX7?

 

I want to try the new issue JJ tubes that are supposedly pretty good.

post #5870 of 10504
Quote:
Originally Posted by mab1376 View Post
 

 

Are the 12AX7 and 6DJ8 the same pinout?

 

It seems you didn't need any kind of adapter for this, would that be the same for the 12AX7?

 

I want to try the new issue JJ tubes that are supposedly pretty good.

 

No. As above, these are normally 12V tubes, and even though the triode elements have the same pin-out, the heaters are different. Unless you want to try to rig up an external heater power supply, the easiest way to use them as power tubes is to purchase these adapters, which reconfigures the heaters for 6V circuits.

 

http://www.ebay.com/itm/Two-adapters-for-12AU7-ECC82-6CG7-TUBES-amplifier-/260716251584?pt=Vintage_Electronics_R2&hash=item3cb3e649c0

post #5871 of 10504

Have been listening to the 6N23P tubes (6DJ8 family) as power tubes with a GE 6BX7 as driver, which is an excellent tube. The treble and midrange are very good sounding, but the bass has a hollow quality to it when you crank up the volume, as if it is running out of steam. Maybe this is what Gibosi meant when he thought these tubes would not have enough power. Had the same impression with 6BZ7 tubes as power tubes.

 

In any event, the 6DJ8 type tubes can compete with the 6N6P family as power tubes. In addition, they can be found very inexpensive as long as it doesn't say Amperex on them.


Edited by mordy - 4/17/14 at 9:26am
post #5872 of 10504

I think buying a Balance and match tubes are just rip-off.

post #5873 of 10504
Quote:
Originally Posted by i luvmusic 2 View Post

I think buying a Balance and match tubes are just rip-off.
Unless you have a balanced amp like the MK VIII where you want matched pairs on each side.
post #5874 of 10504
Quote:
Originally Posted by TrollDragon View Post


Unless you have a balanced amp like the MK VIII where you want matched pairs on each side.

I'am using a RCA 6SN7 that according to the sellers measurement reading marked on the tubes are way out of balance and i can't tell any difference.

post #5875 of 10504
And again with the LD which is NOT designed to run the octals propery, you wouldn't be able to tell since the tube is underpowered... rolleyes.gif
post #5876 of 10504
Quote:
Originally Posted by TrollDragon View Post

And again with the LD which is NOT designed to run the octals propery, you wouldn't be able to tell since the tube is underpowered... rolleyes.gif

Thanks good to know because some vendors are offering that service and it's not free.

post #5877 of 10504
We don't need matched tubes for our amps... So it would not be worth buying them.
post #5878 of 10504
Quote:
Originally Posted by gibosi View Post
 

 

While this is true for all-tube amps, where driver tubes actually "drive" the output tubes, in the LD 1+, the driver tubes don't really "drive" anything. And in fact, if one wanted, the tube stage can be bypassed by a straight wire, and the amp would still work perfectly fine, minus the tube "flavor". With no interaction between the tube and op amp stages, the op amp simply amplifies the audio signal after it has been "flavored" by the tube. And therefore, I am quite confident in saying that the C3g is inherently a bit more forward than my reference Sylvania, all else being equal.

 

But of course, as those of you who have power tubes know, finding and selecting driver and power tubes with just the right synergy is half the fun. And I do hope to be able to eventually find and purchase an OTL amp with 6AS7 type power tubes so that I can double my fun too. :)

 

Hi g.

Yes indeed, having a neutral power stage - for comparisons at least - seems very useful for assessing different drivers...and interesting that you and mab find a forward signature for the C3g, which I only found with the Sylvania VT231.

 

ALSO FOR ANYONE interested in different power tubes....

 

On the subject of synergy - plus TDs reiteration of matched tubes not being necessary in our LDs - I have just completed my first adapter for the Tung Sol 7N7 as powers(Sylvania chrome-top), after having foolishly(?) assumed that being a loctal-version 6SN7 the pin-out would be the same!... and double SHOCK/SURPRISE/BEWILDERMENT...then JOY...

 

Firstly, after resin getting where it shouldn't!, it actually worked...

 

Secondly, even before adapter burn-in, I could not believe my ears...something that doesn't seem to have worked well for folks before now...with the 7N7 in the right channel and the Psvane in the left - absolute MAGIC! NOS American plus young(ish) Chinese? - NO WAY is what I was expecting...certainly not what (at the moment anyway) appears to be a very happy marriage of the best of the Psvane and that of the VT231...the spatial clarity of the former, with a bit more of the mids and bass of the Sylvania/Tung Sol.

Obviously I need to see if this holds for my other test pieces, but at the moment I am somewhat gobsmacked...so perhaps experimentation with 'mix and match' of power tubes is in fact a possible option after all!! What is there to lose, I ask?

 

So another step forward in the power tube saga - for me, anyway. Should be interesting to see what happens with the two 7N7s...but that will have to wait a wee while, I'm afraid...those adapters are a bit of a pig to make - I defy anyone to make one with a 22mm case!!...Of course, any sensible person just buys the ready-made 7N7 to 6SN7 adapters and piggy-backs onto the 6CG7 adapter...but TWO lots of degradation? - not for me!

 

Anyway, time to come back down to Earth and get on with the chores...will check later to see if I was simply hallucinating after too much strong coffee :blink: 


Edited by hypnos1 - 4/18/14 at 6:48am
post #5879 of 10504
Quote:
Originally Posted by hypnos1 View Post
 

So another step forward in the power tube saga - for me, anyway. Should be interesting to see what happens with the two 7N7s...but that will have to wait a wee while, I'm afraid...those adapters are a bit of a pig to make - I defy anyone to make one with a 22mm case!!...Of course, any sensible person just buys the ready-made 7N7 to 6SN7 adapters and piggy-backs onto the 6CG7 adapter...but TWO lots of degradation? - not for me!

 

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.

post #5880 of 10504

how do you read the date on tubes?

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