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Little Dot MKIII Tube Rolling - Page 120

post #1786 of 2853
Yeah, those are the ones. They aren't Mullards since there are no Phyllips/Mullard codes on them. They are pretty in your face which maybe other peoples cup of tea. I thought they sucked, lol! They're cheap though!
post #1787 of 2853
I bought SemiAudiophile's 6H30Pi-EH tubes. I put them in about a half hour ago. He hadn't used them so they are basically new.

I can say that I think the sound is louder - the amp seems more powerful.

Things seem a bit clearer - the stereo imaging is better and the soundstage a little wider.

Highs are crisp - there's no more of that silky smooth, yet undetailed sound that I was getting with some of the driver tubes (1958 Mullard EF95 in there now).

Is this consistent with what other people hear with upgraded power tubes or is this placebo?

The amp does seem to be running a bit hotter. What are the dangers of running these tubes? Will the higher temperature cause the tubes to burn out faster, or is there a chance the amp could be damaged.

This is an amp purchased in February so it has the correct resistor.
post #1788 of 2853
post #1789 of 2853
Can anyone tell me whether the tube rolling suggestions in this thread for the MKIII can also apply to the MKIV SE?
post #1790 of 2853
Quote:
Originally Posted by Philski View Post
Can anyone tell me whether the tube rolling suggestions in this thread for the MKIII can also apply to the MKIV SE?
The driver tubes can...not the power tubes....
post #1791 of 2853
The M8161s finally come with very good package. They both are in box with matched label. They read like:
Valve Electronic
CV 4015 / QDD
0621 / 5960 99 000 / 4015

The label on the tube is:
front: Mullard M8161 made in Gt. Britain.
back: 6065 / 7844 / CV4015 / KB / QDD

Maybe some of you can help to decode these numbers?

After I put in the jumpers and tubes, turned on, and immediately, I found the sound is much clear with good air and space between sound sources. The scratchy feeling is totally gone. Vocal sounds still smooth and now with good airy feeling. The sound stage is still forward and smaller comparing to Arietta, but is farther and more spacious than that of old M8100 tubes. I am very surprised for the improvement.

Even though they have not been burn in, I already like its sweet sound much better than M8100. Maybe they were old and due to be replaced or maybe it is just EF95's family sound. But thanks to all who have directed me to explore EF92 tubes. This pair of new tubes finally bring back my interest in tube amp (I was quite disappointed before).

Now I guess I'll try to get some EF91 to see if that will sound better or too airy for me. Maybe Amperex M8083 EF91 for the start? Other suggestion? Thanks again!


Quote:
Originally Posted by dukja View Post
Thank you both for the very helpful information. I got two pair of Russian power tube for $16 and one pair of M8161 for $25 from ebay. They claimed to be matched with some measured numbers (but they have multiple pairs. so...)

Hopefully, it will clean up the LD sound a little bit. The more I compare LD (old tubes) with Arietta, the more I found that the sound quality of LD is kind of scratchy at certain freq. bands. Violin and vocal sound acceptable but closer to me with LD, but piano sounds rough(again certain freq. bands are not right). It makes me switch to Arietta whenever I listen to piano works. I'll see if the new tubes help.
post #1792 of 2853
M8161 Mullard type code for premium EF92

6065 US RMA/RETMA/EIA type number

CV4015 UK government type code

5960 99 000 4015 NATO stock number

5960 = thermionic valve, 99 = UK, 4015 = CV4015

7844 date YYWW

KB / QDD made to UK government specification by Mullard at Mitcham (I think)

Is there an etched code on the tube?
post #1793 of 2853
Thanks! It is good to know the date code. They both has matched codes, which help to ensure that they are likely to be matched ones as the vendor claimed.

I don't know anything about etched code. Where can I find it on the tube?

Quote:
Originally Posted by Oskari View Post
M8161 Mullard type code for premium EF92

6065 US RMA/RETMA/EIA type number

CV4015 UK government type code

5960 99 000 4015 NATO stock number

5960 = thermionic valve, 99 = UK, 4015 = CV4015

7844 date YYWW

KB / QDD made to UK government specification by Mullard at Mitcham (I think)

Is there an etched code on the tube?
post #1794 of 2853
Quote:
Originally Posted by dukja View Post
I don't know anything about etched code. Where can I find it on the tube?
Like the dark characters here:

post #1795 of 2853
Thanks for the pointing. One has
6Y1 (or 6YI)
R8G3

Another one has:
6Y1
R8H2

What do those mean? Thanks again for the education.
post #1796 of 2853
6Y=CV4015, M8161 1=version 1

R=Mullard, Mitcham 8=1978 G=July 3=3rd week of month / H=August 2=2nd week of month

The tubes were made a couple of weeks apart (nothing to worry about) but CV-labeled during the same week (7844).
post #1797 of 2853
Cool! You are the man.

Is there anywhere on the net that we can find such great info? Or we just have to consult you every time we got tubes.

Really thanks, I never though that there is so much info in such encrypted form.
post #1798 of 2853
Quote:
Originally Posted by dukja View Post
Is there anywhere on the net that we can find such great info? Or we just have to consult you every time we got tubes.
I hope not.
post #1799 of 2853
Just an updated "Review" on the WE403b tubes I got a week or two ago after using them everyday. I think I've found the tubes I was looking for all this time. They sound wonderful. Very balanced tubes.
post #1800 of 2853
had my Amperex M8083 EF91 for a while now and had a good listen on them. to describe them, i wouldn't exactly say spacious, although they are pretty spacious. i would say they are as spacious as the other EF95/EF92 families but maybe just a tad more. i didn't like them at first listen, they sounded a bit harsh/edgy. they are definitely softer than the other family tubes. i usually have my amp set between 9-10 o'clock position. but with these i have them set between 12-1 o'clock. after a good 2nd, 3rd listen, they definitely don't sound as warm/lush as the Amperex 5654 EF95 but they do sound smooth, natural kinda like the mullards M8161's and quite detailed. they don't seem to sound bright at all and they definitely have that Amperex sound to them (that powerful, robust sound).

i still don't feel that my HD650's go well with this amp though. after all the tubes i tried so far, my HD650's still sounded veiled/bloated when matched with this amp. just not as detailed and clear as using a SS.
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