Little Dot Tube Amps: Vacuum Tube Rolling Guide - Page 20

Quote:

Originally Posted by mordy 

Does the 'dead soldier" have a white coating inside the glass envelope instead of silver? If not, just try the pen knife trick to scrape off the oxidation on the pins, and the tube might work.

(The white coating indicates that the tube lost vacuum and is dead.)

Mordy thanks !   It's working now,however,I had to clean that stubborn tube for a solid 40 minutes and it finally worked. I took it out and put a very light coating of Deoxit on it and it stopped working again. Another 25 minutes scraping the pins then lightly tapping the tube with my finger and it's finally working. Guess this one wont have much of a life span . In fact I use a box cutter with a small thin blade to lightly scrape the pins but I've never had scrape the crap out of them like this one lol !

Quote:

Originally Posted by infinity650 

these days I got my Mullard EF 91s. A pair of the CV4014 (civilian version) and a pair of M8083 large shield (military). Expect from the print on these tubes, they look absolutely identical! Every detail which can be seen with bare eyes is exactly the same to me... Which leads me to the question: is there really a difference between them?

There isn't any (if of same vintage). CV4014 is a UK government code for what Mullard called M8083, a special quality EF91.

CV = common valve (see http://www.tubecollector.org/cv-valves.htm).

Ok, thanks for the reply. Everywhere is said the military version sound better. I'll let them burn in properly and then listen to them intensively again for my judgement.

Don't believe everything you read. What Mullard called M8083, the UK military called CV4014.

Yeah, nice one! :D

Look, some of these tubes have decades of oxidation on them, but I am surprised that it took you so long to get it off. (Another thing I tried is to repeatedly push in and take out the tubes from the socket, but scraping with a thin blade works better.)

Anyhow, these things make tube rolling even more interesting.

How would you describe the difference in sound between 6AG5 and 6AK5 tubes?

Hello,

are we sure EF96 / 6AG5 tubes really work without problems in Little Dots?

Quote:

Originally Posted by mordy 

Look, some of these tubes have decades of oxidation on them, but I am surprised that it took you so long to get it off. (Another thing I tried is to repeatedly push in and take out the tubes from the socket, but scraping with a thin blade works better.)

Anyhow, these things make tube rolling even more interesting.

 

How would you describe the difference in sound between 6AG5 and 6AK5 tubes?

I'm new to tube swapping in my 47 years as a solid state guy and tinkering with circuits. As long as I've owned the amp I used the stock tubes till recently.On that one stubborn Raytheon-the pins looked no different than any other tube I have but I understand about corrosive contacts considering these tubes may be from the late 50's-60's.Overall,the 6ag5 sounds a bit smoother in general .A slight but noticeable upgrade from the stock tubes. The Sylvania's and Tung Sols were my favorites till I got the Raytheons in there.Those to me provide a more dynamic  warm midrange sound I did'nt know existed till now but they are very microphonic. Not sure if it's just my pair or a Raytheon signature for this type of tube.

So, once again: does anybody know for sure about 6ag5 (ef96) tubes working in the MK IV (SE) model? And if yes, which brands/types can you guys recommend best?

Greets

Nik

By rhe way: I'm more and more pleased with the Mullard M8083s. Great tubes, nice and gentle sound overall, very good treble and detail, wide soundstage... tube rollers: give them a try, they're worth it!

I'm sorry I cannot give you a complete answer but the Ebay seller I bought my tubes from states the 6ag5 are a good upgrade for the 6ak5. I have'nt had any problems with all the sets I own used in the MK III other than the one tube stated earlier. Unfortunately, I think he's just about out of them.I've so far tried cbs,rca,Tung Sol,Raytheon,and Sylvania-the last three being my favorites.

I never received the jumpers when I bought my amp.If anyone can tell where to obtain them would be great as I'm limited to ef95/ef96 .

To the best of my knowledge the jumpers are standard and the same that come with many hard drives for different pin configurations. If you have some hard drives sitting around you may already have them, or any tech friend or computer repair shop should have them, probably for free....

However, if you are able to use your amp I am sure that they are in place already, and you just have to move them from one setting to the other. Look in the second set of oval holes under the front of the amp and see if you can see the jumpers there. They look like little U shaped things that push on to two pins. You should see the letters EF95 if they are in the EF95 position. When you move them to other position you will see the letters EF92. (You will need a small needle nose pliers or similar to move them.)

Good luck!

Tube rolling becomes an addiction! :D  But a pretty nice one! "Tube rolling seriously doesn't harm you or others around you - just your wallet" :D

Just got recently the LD MK3  along with it 4 unmatched 6h6p power tubes  is it ok to used them if they are not matched. or it might damage something.

Rolled my first tubes on Thursday night.  Replaced the stock drivers on the MKIV (non-SE version) with the NOS GE-JAN 5654-W tubes recommended in this thread.  After about 8 hours of burn-in, I can notice a definite improvement.

I felt the stock tubes rolled off the treble a tad too much, especially with the already laid back treble of the HD650s.  The GE tubes definitely add more noticeable presence and a bit (but just a bit) of sparkle to the upper range.  It still doesn't make the 650s "bright" by any stretch, but there is a bit more emphasis there.  However, still very smooth treble -- never harsh or fatiguing in any way.  Just eminently listenable.

It was exactly the tweak I was looking for.

The OP is also correct that the sound is quite airy.  Bass is present, but because of this airy-ness, it may actually seem, viscerally, a touch more subdued.

Have been listening to mostly acoustic-y singer-songwriter stuff, and the cans just sing.  Will have to try something a little harder later on and see how they hold up. 

Next on tap are the Vohkshods (which apparently, I paid way overprice for from Yen Audio, but what are you going to?)  But I think I'll live with GE's for a while yet.

I can see how rolling your own can get addictive!

Quote:

Originally Posted by elecsheep9 

Rolled my first tubes on Thursday night.  Replaced the stock drivers on the MKIV (non-SE version) with the NOS GE-JAN 5654-W tubes recommended in this thread.  After about 8 hours of burn-in, I can notice a definite improvement.

 

I felt the stock tubes rolled off the treble a tad too much, especially with the already laid back treble of the HD650s.  The GE tubes definitely add more noticeable presence and a bit (but just a bit) of sparkle to the upper range.  It still doesn't make the 650s "bright" by any stretch, but there is a bit more emphasis there.  However, still very smooth treble -- never harsh or fatiguing in any way.  Just eminently listenable.

 

It was exactly the tweak I was looking for.

 

The OP is also correct that the sound is quite airy.  Bass is present, but because of this airy-ness, it may actually seem, viscerally, a touch more subdued.

 

Have been listening to mostly acoustic-y singer-songwriter stuff, and the cans just sing.  Will have to try something a little harder later on and see how they hold up. 

 

Next on tap are the Vohkshods (which apparently, I paid way overprice for from Yen Audio, but what are you going to?)  But I think I'll live with GE's for a while yet.

 

I can see how rolling your own can get addictive!

The Voshkod are overpriced you say i paid $36.00 from Yen Audio yesterday  for a matched pair are they cheaper elsewhere, any stores we should know about , Anybody !