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Little Dot Tube Amps: Vacuum Tube Rolling Guide - Page 2

post #16 of 7455

Hi Dept of Alchemy,

 

This tube rolling guide is amazing! I agree with almost everything there. Would be nice to add the Telefunken and Raytheon small mica EF95 tubes to the list. It is obvious that a huge amount of work and time went into this guide. Many thanks!

Looking forward to the power tube reviews which are not included yet.

The only thing left after this is to point out which combinations of power tubes and driver tubes work best.

(From a different post: I found it noteworthy that the 6N6P power tubes tame the overpowering treble of some tubes and make them very listenable.)

 

I am also questioning how important tube matching is, having heard that there are very large differences with a range of tolerance of up to 10% in the production lines. Another thing I do not understand is the statement in section 4.1 that power tubes failed after 100 hours due to mismatching. According to David of Little Dot the amplifiers are designed with totally separate circuits for right and left to the point that you can run different tubes simultaneously on each channel without causing any problems. Since I also had one of my OEM power tubes fail after five months (none of the driver tubes have failed during use yet), perhaps one has to conclude that the power tubes are more prone to failure than driver tubes.

 

In your conclusion you recommend the RCA black plate 5654 tubes for "solid all-around performance, great bass response and availability." I could not agree more. Right now I am enjoying the RCA 5654 tubes I have from Aug 1959 (rectangular slanted getters) and Novosibirsk 6N6P 1975 tubes. This combination is wonderful in my system with better bass than the Mullard M8100/EF95 tubes and has a lively, dynamic, toe-tapping inducing presentation. The sound as I am writing this is positively intoxicating. Powerful, tuneful bass, a beautiful, mellow mid range, exquisite highs, tremendous detail and a glorious 3D sound stage.

And for frugal people like me, I especially enjoy that all four tubes cost me $10.64 incl. shipping (even though I had to buy 9 RCAs and four 6N6Ps to get these prices).

 

post #17 of 7455

I really enjoy my EF91/CV4014 GEC tube (not review here) and it is quite a gem. I have ordered the EF92 United Electron EF92 tube based on your comments and I will see how my comments compare to yours.   

post #18 of 7455

Impulsive, Voshkod 6ZH1P-EV = mine 6J1P-EV .  The trick is getting the ones made from 1970 to 1980.

 

Take in consideration, the tubes on ebay called 6ZH1P-EV are 10 times more expensive (30$ for a matched pair).

 

Don't get tricked ! Get the set of 10 tubes 6J1P-EV's from 1970's for 20$ shipped.

 

On the question how do these sound compared to M8100's, I had writen a lot before... For our  headphones, Mullards are better match. For Sennheiser -> Russians. 


Edited by AlexRoma - 7/25/11 at 5:11am
post #19 of 7455

Hi AlexRoma,

 

I have a pair of Voshkod 6Sh1P-EV tubes from 11/73. Are these identical to the 6ZH1P-EV / 6J1P-EV tubes?

post #20 of 7455

thanks for experiences guys.

I just wonder how is overall sound quality.

After reading this, i am pretty sure i should give Voshkods and Tung-Sols a try.

Voshkods, because of the best ranking here and Tung-Sols because of darker sound.

That might be what i am looking for :-)

Also thanks for explaining tubes names, price difference is incredible!

post #21 of 7455

Hi AR,

 

Found the answer:  Zh (Russian: Ж) - sharp-cutoff pentode. (also transliterated sh or j). It is the same exactly. Problem is that I don't like the sound - will burn them in an extra 100 hours and see...   

 

Here is a link that will tell you all you want to know about Russian tube designations:

 

http://en.wikipedia.org/wiki/Russian_tube_designations

post #22 of 7455

My United Electron EF92 tube came and after burn in it was a good EF92 tube and it matched some of the comments you made for it. I prefer the GEC EF91 tube. The GEC tube has far greater soundstage more depth rather than width like the United Electron. The GECC also has more dynamic range to work with and seems to be able to push the Russian 6N6P harder to higher output. My lowly MKll now seems to be new stronger model. It did had a bit of grain at first but it migrated out after a bit of tube burn-in. GEC has great resolving power and will show weakness in the audio chain. Well recorded material sounds great and in certain aspects match some of the sound characteristics in my Stax headphones setup.  

Cons: The GEC tube needs a long time to warm up time like at least 40 mins to bring out its characteristic sonic signature. Poor recordings or poor upstream devices can sound harsh because of the resolving power of the tube. My journey for the best driver tube for my Little Dot has ended on a very good note.

I have just one more power tube to roll, A Russian 6N6P tube that has 10 mg of gold on the grid wires. I decided not to try the 6H30 DR tube since it is quite costly and I prefer to save the money to go to unamplified concerts. The gold Russian 6N6P is much cheaper and it just came in before the weekend and I will compare it with two of my other power tubes for the LD.     

post #23 of 7455

Hi John57,

 

I have seen gold plated 6J1P tubes (with gold grid), but I was not aware of 6N6P tubes with gold grid. Could you give the reference where to buy them?

Looking forward to hear about your experience with these power tubes.

post #24 of 7455

There was just a three day period that the gold 6N6P tubes were available from this vendor with just three matched pairs on sale. The tubes were in a cardboard box in a plastic bag. Lucky the tubes were not crushed.

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=130542830285&ssPageName=STRK:MEWNX:IT

This may be the same vendor that you were talking about 6J1P having Gold-Platinum grids. The seller price seems quite reasonable and well documented. It takes about three weeks for shipment from Russian Federation.

The gold girded 6N6P tubes are burning in as we speak. They are a bit heavier than the stock 6N6P and the heaters do not glow as brightly. I may start forming an opinion maybe late Sunday. 

post #25 of 7455
Thread Starter 
Quote:
Originally Posted by john57 View Post

My United Electron EF92 tube came and after burn in it was a good EF92 tube and it matched some of the comments you made for it. I prefer the GEC EF91 tube. The GEC tube has far greater soundstage more depth rather than width like the United Electron. The GECC also has more dynamic range to work with and seems to be able to push the Russian 6N6P harder to higher output. My lowly MKll now seems to be new stronger model. It did had a bit of grain at first but it migrated out after a bit of tube burn-in. GEC has great resolving power and will show weakness in the audio chain. Well recorded material sounds great and in certain aspects match some of the sound characteristics in my Stax headphones setup.  

Cons: The GEC tube needs a long time to warm up time like at least 40 mins to bring out its characteristic sonic signature. Poor recordings or poor upstream devices can sound harsh because of the resolving power of the tube. My journey for the best driver tube for my Little Dot has ended on a very good note.

I have just one more power tube to roll, A Russian 6N6P tube that has 10 mg of gold on the grid wires. I decided not to try the 6H30 DR tube since it is quite costly and I prefer to save the money to go to unamplified concerts. The gold Russian 6N6P is much cheaper and it just came in before the weekend and I will compare it with two of my other power tubes for the LD.     


I'll be posting the power tube reviews shortly, just waiting for the gold Russian tubes to arrive. =)

 

post #26 of 7455

I had a surprising discovery in the power tube rolling with results that I was not expecting. Right now I am rechecking on the validity of my results with all of my headphones and other amps.  

post #27 of 7455

Isn't this what keeps up the interest in tube rolling? You never know what you will find. Tubes are very mysterious.

post #28 of 7455

Hi DoA,

 

Your guide is comprehensive and insightful.  As I continue to explorer tube-rolling I am certain to refer to this guide for months to come.  I just received my pair of Mullen 8100s.  I must say the first impression (less 5hrs burn-in) is I can definitely tell a difference between them and the RCA 5654 tubes.

 

The RCA tubes I bought already burnt-in with my LD MK-III a few weeks ago.  The RCAs bass is more prevalent, the highs crisp and more detailed.  I definitely won’t be throwing out these tubes.

 

Now, the Mullard is noticeably warmer even in its current stage of burn-in.  They have body and great depth.  The mids are slightly laid back.  I don’t really know if it is too laid back at times, it’s still too early to tell. No listener fatigue so far.  I’ve only listen to only a few albums so far – Bob James, Chris Botti, Karrin Allyson and Fiona Apple, but everything you’ve described of the Mullard is spot-on.  I will continue to explore it’s sound listening to additional artists and larger music genres.  These tubes are a great complement to the RCAs.

 

The only doleful thought is knowing that as the tube ages and its sound matures they move closer to their death.  Too bad tubes cannot last forever.

 

Thanks,

post #29 of 7455

Hi G~M,

 

From what I understand the average tube lasts around 2000 hours, which is quite a lot. The Russian tubes with the EV/EB rating are supposed to last 5000 hours. The Russian DR tubes are designed to last 10,000 hours.

It is my impression that certain variants of tubes were designed to last 10,000 hours. Mullard had something called the M Series (I only saw EF95 type tubes from the M Series once on Ebay); the GE Five Star tubes are also supposed to last 10,000 hours.

Recently I bought a pair of 5654 Amperex tubes made in Holland with the letters PQ, which stands for Premium Quality. These are also supposed to last 10,000 hours. Early listening to the PQ tubes is very promising, but I have to wait to form an opinion.

The obvious answer to the question about tubes being used up is to buy several of your favorite tube.

Part of the tube mystique and the fun of collecting tubes is that you sometimes find one tube in the US, and the exact match in Bulgaria!

post #30 of 7455

Hi Mordy,

 

Thanks for the info.  I just received my 6J1P-EV set from Ebay yesterday.  This may be the same set of 10 tubes AlexRoma mentioned in his post selling for $20 shipped.  I am not to happy with them.  For one, the arrived unboxed  and many of the tubes have no apparent markings on them.  There is no way of verifying the manufacturer, make, year or anything else (that I am aware of). It sound like I'm talking about cars.   If I had to do it over again I would have bought a matched pair from a more reputable seller even at a higher cost.  I suppose I may put the other unused tubes on ebay. 

 

I will likely keep one pair or two though.  The sound quality at the moment (6 hrs on burn-in) at clearly the worst of the three pairs I own (Mullards 8100\CV 4010 and RCA 5654)

It sounds a bit harsh but to be fair I must allow more time for burn-in.  I did notice subtle improvement after 4 to 6 hours of use.

 

Do anyone know or have the ability to match tubes?  I bought this set of ten but would be willing to either donate a pair or pay in exchange for having them matched.

 

Thanks,

 

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