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Little Dot Tube Amps: Vacuum Tube Rolling Guide - Page 305

post #4561 of 10575

I just got my 6HM5(Yugoslavia)it sound really good but when i turned on my LD 1+ i saw a SPARK from the bottom of the tubes. Is these normal?

post #4562 of 10575

I just switch the 6HM5 from LD 1+ to LD MK III it sound alot better with MK III(IMO)but that SPARK still there i guess that spark is normal but should i worry about it.

post #4563 of 10575
If you mean it kinda flares up on power up that is normal.
post #4564 of 10575
Quote:
Originally Posted by kvtaco17 View Post

If you mean it kinda flares up on power up that is normal.

OK THANK YOU!

post #4565 of 10575

Hi i luvmusic2,

 

Please read post 3544 on page 237 from one of the members on this forum. The flash is a quick heating up feature for military applications and normal for this specific tube.

post #4566 of 10575
Quote:
Originally Posted by mordy View Post
 

Hi i luvmusic2,

 

Please read post 3544 on page 237 from one of the members on this forum. The flash is a quick heating up feature for military applications and normal for this specific tube.

Sure i will THANK YOU!

post #4567 of 10575

Tubes i have so far 6HM5,Motorola 6BE6,RCA 6DK6,TUNG-SOL 6CS6,RCA 6DT6,BRIMAR EF92,International Sylvania 6AK5,PHILIPS MINIWATT EF91,JAN-GE5654W Do you guys have more plug and play tube suggestions?

post #4568 of 10575

Hi i luvemusic2,

 

Go to page 77 post #1154. The column on the left with the heading EF95 lists all plug and play tubes on the EF95 setting with a green yes.

 

To the right of this column is a column labeled EF91/92. Any tube with a green yes under this heading is plug and play using the EF92 setting on the amp.

 

The following power tubes are plug and play (the big tubes in the back of the amp):

 

6N6, 6N6P, 6N6P-i, 6N6P-IR, 6H30, 6H30-DR (the last two tubes only with circuit revision v.2)

 

6CG7 and 6FQ7

 

Which driver tubes do you like the best?

post #4569 of 10575
Quote:
Originally Posted by mordy View Post
 

Hi i luvemusic2,

 

Go to page 77 post #1154. The column on the left with the heading EF95 lists all plug and play tubes on the EF95 setting with a green yes.

 

To the right of this column is a column labeled EF91/92. Any tube with a green yes under this heading is plug and play using the EF92 setting on the amp.

 

The following power tubes are plug and play (the big tubes in the back of the amp):

 

6N6, 6N6P, 6N6P-i, 6N6P-IR, 6H30, 6H30-DR (the last two tubes only with circuit revision v.2)

 

6CG7 and 6FQ7

 

Which driver tubes do you like the best?

TUNG-SOL 6CS6/EH90(2 Pairs)and 6HM5(another pair on it's way)any tubes that i really like i always buy 2 pairs. so far i have 17 pairs some are double pairs.So for the 6CG7 and 6FQ7 are they better than 6N6P-i?THANKS!

post #4570 of 10575

That suggest i like all my TUBES.....

post #4571 of 10575

Hi 2,

 

 

"So for the 6CG7 and 6FQ7 are they better than 6N6P-i?" That's a good question. However, unless you want to spend mega bucks for the 6H30-DR tubes, the 6N6P-IR are the best power tubes, and the IR's should be the comparison.

 

So how do the 6CG7/6FQ7 compare to those tubes? I am afraid that I cannot give you a solid answer yet, because this is uncharted territory, and we tried the 6CG7s for the first time as power tubes yesterday. I would say that you need 50-100 hours of burn in to stabilize the tubes.

 

Then you have the human factor. I am used to a certain sound that I am very familiar with, using the 6N6P-IR as reference power tubes. When I try a new tube I have a frame of reference, and I can detect small differences. Now everything changed, and I have to try to find the right combination of driver tubes for the new power tubes.

 

At this point I can only say that they sound different, and they sound quite good, but not more. (Briefly tried the 6FQ7 GE tubes and some unknown (RCA?) tubes, but it did not sound good - too bright and thin). Tried with the Amperex 6DJ8 as a driver tube - a little better. Then I stuck in the Sears 6CG7 tubes (Satisfaction Guaranteed Or Your Money Back) nee Sylvania, and things got better. Even better when I used my Tung Sol 6SL7Gran Tourismo tube as a driver.
 
It's like moving into an unfamiliar neighborhood where you don't know the streets and you don't know your way around. In addition, audiophilia nervosa sets in, things don't feel right and don't sound right; the music doesn't get to you the right way. The magic is gone, kind of...
 
Oh well, what don't we do to advance the science of tube imperfection....
post #4572 of 10575
Surely the obvious alternatives to the 6N6s are the 5687, 6900 (rare and expensive) and the E182CCs (7119?) type tubes. They just need a simple adapter for to work.
post #4573 of 10575

Granted, but the question asked was which tubes work plug and play without any modifications.

 

Need an answer to the following:

 

With the 6CG7 tubes the octal driver tube I am using runs much hotter than with the IR tubes. The plate voltage is 173V, which is higher than what I measured in the past with the IR tubes - around 147V.

 

Could it be that such a high voltage is detrimental to the tube? (Heater voltage is 6.3V and grid voltage is 1.33V).

post #4574 of 10575

 

 I have been auditioning the Amprex 1968 OG 6DJ8 I received from Audiofanboy with Mikelap's amazing adapter and my mind is Blown! Wow !

 

Gary


Edited by mojorisin35 - 1/3/14 at 8:49am
post #4575 of 10575
Quote:
Originally Posted by mordy View Post
 

Granted, but the question asked was which tubes work plug and play without any modifications.

 

Need an answer to the following:

 

With the 6CG7 tubes the octal driver tube I am using runs much hotter than with the IR tubes. The plate voltage is 173V, which is higher than what I measured in the past with the IR tubes - around 147V.

 

Could it be that such a high voltage is detrimental to the tube? (Heater voltage is 6.3V and grid voltage is 1.33V).

 

Speaking of voltages, has anyone formally measured the voltages for both 6N6P and 6N30P tubes? Since I don't have any 9-pin socket savers - let alone some with test points - it would pretty difficult to measure for me...

 

Fresh measurements with the Amperex Holland PW 6922:

 

Wall = 224V

Heater = 5.76V (despite the 6922 using less current than both the 7308/E188CC...)

 

                   L                     R

Cathode = 2.08V               2.09V

Anode    = 75.6V              74.6V

 

Heater voltage is out of spec as usual, but then again the different premium 6DJ8 tubes I've tried up to here seem to do quite well regardless, so I guess I should just stop worrying about it... Tubes might have a longer life that way too, maybe...

 

Triodes are almost a perfect match as is almost always the case with the premium Philips 6DJ8 types. Fine tubes, I reckon.

 

I was originally asking about formal 6N6P & 6N30P measurements since I recall someone mentioning that the driver tube plate voltage should be about half of the power tube plate voltage; and while my 75V driver tube plate voltage and most other folks' 80V figures for that type seem slightly below the "nominal" 90V, it is exactly half of Mordy's reported 6N6P-IR plate voltage... So, it should seem like yet another sign the LD amps were made to accept 6DJ8s...

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