Shootout of Nos 6sn7 tubes

thomask

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Dec 9, 2018
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#41
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thomask

Well-Known Member
Dec 9, 2018
554
395
75
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Washington State, US
#42
With respect to the 1578 tube, the date is acid etched at the 6 o’clock position within the Melz factory stamp. The first two are Roman numerals denoting the week of manufactured followed by the year. I posted a picture (difficult to picture) but you ca clearly see the “76”. Hope that helps
I received tube 2 hours ago.

It blow my mind with nice decay and body, deep bass, wide and deep soundstage.

I had not been blown by TS bgrp just impressed with its transparency.

To me this one is one tier above TS bgrp.

I am listening to "The Wall". which sounds full and powerful without subwoofers.


https://www.ebay.com/itm/133366164135


I ordered one more tube as spare.
 
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Brf

Well-Known Member
Sep 21, 2012
32
8
83
#43
Thomask, congrats on acquiring a pair of 1578. Looking forward to your full review. The 1578 tube is very detailed and does not smear the instruments together. Some would call this “air”. Imho, the 1578 does not have any short comings. It has a deep bass, fully fleshed out midrange and a very extended high end without any compression. Very dynamic.
 

thomask

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Dec 9, 2018
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#44
Thomask, congrats on acquiring a pair of 1578. Looking forward to your full review. The 1578 tube is very detailed and does not smear the instruments together. Some would call this “air”. Imho, the 1578 does not have any short comings. It has a deep bass, fully fleshed out midrange and a very extended high end without any compression. Very dynamic.
I heard that there are difference between 1578 made in 1970's and 1980's.

The one that I got today was made in 1980's.

Next week I will get tubes made in 1970's.

I will do comparison between them.
 

Brf

Well-Known Member
Sep 21, 2012
32
8
83
#45
I heard that there are difference between 1578 made in 1970's and 1980's.

The one that I got today was made in 1980's.

Next week I will get tubes made in 1970's.

I will do comparison between them.
I own both 70’s and 80’s tubes. The difference is in the plate construction. 1970’s production typically have shinny T-plates and tubes manufactured in the 80s have dull T-plates. Imho, there is very little difference between the two with a slight edge going to the shinny plates based on my listening preference. A lot of people covet the mid 70’s 1578 tubes as this is when production was at its zenith with the strictest QC and highest demand from both military and the atomic industries.

As an aside the latest production 1578 tube that “I’ve” seen was manufacture in 1983
 
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thomask

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Dec 9, 2018
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#46
I own both 70’s and 80’s tubes. The difference is in the plate construction. 1970’s production typically have shinny T-plates and tubes manufactured in the 80s have dull T-plates. Imho, there is very little difference between the two with a slight edge going to the shinny plates based on my listening preference. A lot of people covet the mid 70’s 1578 tubes as this is when production was at its zenith with the strictest QC and highest demand from both military and the atomic industries.

As an aside the latest production 1578 tube that “I’ve” seen was manufacture in 1983
Thanks a lot for your valuable information.

Since I use pair of 6sn7 in LM508 and quad 6sn7 in Freya, i consider ordering more.

Just out of curiosity, i also had ordered cheap 6n8s tubes for comparison.

https://www.ebay.com/itm/QUAD-FOUR-Matched-Balanced-Russian-6N8S-6SN7-double-triode-TUBE-NEW-NOS/312402083888?ssPageName=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649

I do not expect them to be as good as 1578.;)
 

thomask

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Dec 9, 2018
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#47
https://www.ebay.com/itm/273874731266?ul_noapp=true

I placed an order of one more pair of 1578 made in 1980

It will take 6 weeks to get it.

This dealer offer 60 days of return.

After having listed to 1578 for 8 hours, I am convinced this is the King of 6sn7 with nice timber, great bass, wide and deepest soundstage.


TS bgrp is not a bad tube but it is over hyped.
 
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analyzer

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May 20, 2016
153
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Torino - Italy
#48
Just out of curiosity, i also had ordered cheap 6n8s tubes for comparison.
I forgot to tell you that I tried also a pair of cheap 6N8s Russian tubes in the past. The result was good but far from the best mentioned above. The sound was a little bit light in the bass and slightly unfocused in comparison to american tubes.
As said previously I was unlucky in my purchases of metal base Russian tubes that were very noisy.
If I'll have not success to sell my actual amp maybe in the future I'll can try these 1578 tubes. My amp needs just some impact and extension in the first octave range.

Final question: I see many ad sales at different prices and it's not easy to make a good choice, tubes are already a difficult choice when you need to find the very best.
 

thomask

Well-Known Member
Dec 9, 2018
554
395
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Washington State, US
#49
I forgot to tell you that I tried also a pair of cheap 6N8s Russian tubes in the past. The result was good but far from the best mentioned above. The sound was a little bit light in the bass and slightly unfocused in comparison to american tubes.
As said previously I was unlucky in my purchases of metal base Russian tubes that were very noisy.
If I'll have not success to sell my actual amp maybe in the future I'll can try these 1578 tubes. My amp needs just some impact and extension in the first octave range.

Final question: I see many ad sales at different prices and it's not easy to make a good choice, tubes are already a difficult choice when you need to find the very best.
It is not an easy job to choose right tube to fit your system and taste.

But having done shootout of more than 14 6sn7 tubes, I am convinced that 1578 is the King of 6sn7 at least to my taste.

Another thing I found out is that almost all Vt231s made in 1940's are excellent just second tier below 1578.

Also most 6sn7 made in 1950's are pretty good for the money except hyped "Bad boy" which is a pretty good tube but overpriced,
 
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#50
Every version of the military 68HC tube with metal base is a little different sounding. Even each year of 1578's are different too. Finding the holy grail is not easy and finding tubes that measure like new is not easy either. Best to stock up on them before they all disappear. I have several versions of 68HC and two or three versions of 1578. The best I think is the 1578 from the 70's.

A other great tube is the Genelec KT-66 from the 60's. A good replacement for the EL34 in many applications. Lasts forever.
 
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thomask

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Dec 9, 2018
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#51
Every version of the military 68HC tube with metal base is a little different sounding. Even each year of 1578's are different too. Finding the holy grail is not easy and finding tubes that measure like new is not easy either. Best to stock up on them before they all disappear. I have several versions of 68HC and two or three versions of 1578. The best I think is the 1578 from the 70's.

A other great tube is the Genelec KT-66 from the 60's. A good replacement for the EL34 in many applications. Lasts forever.
Had you ever tried 1578 made in 1960's?

Some people are of the opinion that they sound better than those made in 70's or 80's.

s-l1600.jpg

I found some 1578 tube made in 60's with five holes but not 1578 logo.

Thus I am not sure whether it is wise to buy it or not.
 
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#52
I have had older ones and ones with no 1578 etched in the glass. Not as good so far.
 
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DaveC

Industry Expert
Nov 16, 2014
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#53
It is interesting the often repeated caveat that the best tube may vary depending on circuit design but it seems like a great majority of folks agree on what the best tubes are.

I've designed and built tube circuits, I think it might be more accurate to say the circuit design can emphasize or minimize the characteristics of the tubes used. The most neutral and resolving tube is going to fit most systems and personal preferences best vs tubes with greater coloration. Of course it's somewhat subjective so many may prefer something more warm, or dynamic, or whatever if it fits their preference or system best, but these seem mostly outliers and the great majority do indeed agree upon which tubes are best.

At least, I've never heard anyone try the metal base Soviet tubes and say they aren't up there with the best if not the best they have tried.

And if you use 6SL7, the there's an identical metal-base Russian tube, the 6N9S, that is also the best of it's type I've tried.
 
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DaveC

Industry Expert
Nov 16, 2014
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#54
Had you ever tried 1578 made in 1960's?

Some people are of the opinion that they sound better than those made in 70's or 80's.

View attachment 65514

I found some 1578 tube made in 60's with five holes but not 1578 logo.

Thus I am not sure whether it is wise to buy it or not.
I wonder when the "1578" designation began? I've heard it's for military applications including nuclear devices or MiG jets, and that they are only tubes that test the best, not different construction... there may not have been "1578" around this early...
 
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thomask

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Dec 9, 2018
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#55
I wonder when the "1578" designation began? I've heard it's for military applications including nuclear devices or MiG jets, and that they are only tubes that test the best, not different construction... there may not have been "1578" around this early...
I found that only tubes made in 70's or later has 1587 logo while similar one with five holes made in 60's does not have logo in it.

13 stock tubes made in 68 are available from USSR dealer. I have not decided whether to go for it.
 

thomask

Well-Known Member
Dec 9, 2018
554
395
75
60
Washington State, US
#56
It is interesting the often repeated caveat that the best tube may vary depending on circuit design but it seems like a great majority of folks agree on what the best tubes are.

I've designed and built tube circuits, I think it might be more accurate to say the circuit design can emphasize or minimize the characteristics of the tubes used. The most neutral and resolving tube is going to fit most systems and personal preferences best vs tubes with greater coloration. Of course it's somewhat subjective so many may prefer something more warm, or dynamic, or whatever if it fits their preference or system best, but these seem mostly outliers and the great majority do indeed agree upon which tubes are best.

At least, I've never heard anyone try the metal base Soviet tubes and say they aren't up there with the best if not the best they have tried.

And if you use 6SL7, the there's an identical metal-base Russian tube, the 6N9S, that is also the best of it's type I've tried.
I also ordered 6n9s a week ago.

So far my favorite 6sl7 is RCA 5691 red base which is better than Mullard Ecc 35.
 

thomask

Well-Known Member
Dec 9, 2018
554
395
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#57
https://www.ebay.com/itm/Raytheon-JAN-CRP-6SN7GT-VT-231-Vacuum-Tubes-1944-Balanced-Matched-on-Hickok/392787627010?ssPageName=STRK:MEBIDX:IT&_trksid=p2

I won this Raytheon Vt231 tube at Ebay auction at 50$ on May 11th.
Including shipping and tax, total cost was 65$ on me.

After receiving this one yesterday, I replaced Melz 1578 with this RT vt213 for examination and comparison purpose this afternoon.

Wow this is the best 65$ that I had spent on audio gadget.
While 1578 sound more dynamic with nice decays, wider soundstage, this RT sound little bit more clean on treble.

The only downside of Melz 1578 is some crackle noise before warmup.

Most of crackle noise is gone after 10 minutes warmup but compared with RT vt231, I noticed slight high frequency noise.

Overall I am still of the opinion that Melz 1578 is the King of 6sn7 with explosive dynamics, deep bass, widest and deepest soundstage.

But valuewise, this Raytheon Vt231 which cost me 65$ is the best value with nice musicality.
 

thomask

Well-Known Member
Dec 9, 2018
554
395
75
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Washington State, US
#58
20200526_163429.jpg

Yesterday I got delivery of 1578 claimed to be made in 1973 (upper one in the photo).

But it appears to be same as the one that I got last week.

Both of them does not have shiny plate.


I compared the sound of both in Line Magnetic 508 amp.

They sounds almost same but slight high frequency noise that I noticed from the lower one is gone in the upper tube :)).

Thus I had decided to keep the lower one as reserve and use the upper one as my "holy grail" of 1578 Melz for the time being.


s-l1600 (4).jpg

I expect to get another Melz 1578 from Russia next Monday June 1st( fast DHL Express shipping from this Russian dealer only 10 day's within order) https://www.ebay.com/itm/Matched-pair-Extremely-rare-1578-6N8S-audiophile-6H8S-6SN7-Metal-base/273874731266?ssPageName=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649


After I receive one next week, I will also do comparison.

s-l1600 (5).jpg
https://www.ebay.com/itm/QUAD-FOUR-Matched-Balanced-Russian-6N8S-6SN7-double-triode-TUBE-NEW-NOS/312402083888?ssPageName=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649

I also got delivery of Nos 6N8S tube yesterday.

After testing 1578 Melz, I also put pair of above 6N8s tube in Line Magnetic 508 for comparison.


Wow this 6N8S tube sounds very similar to 1578 Melz in overall signature while 1578 Melz give slightly more refined sound with wider and deeper soundstage.

But the difference between those two are not that drastic.

I can happily live with this 6N8s if I had not tasted 1578 Melz ;).

I saw the letter Vi71 on the bottom of this tube, thus it could be made in 1971.

20200526_212046.jpg

i also have new production 6N8S stock tube from Schitt Freya+ pre.

They looks similar except red logo in new production tube.

I had done comparison of two tube in LM 508.

Although both of them have similar signature of sound with full bass and sweet treble but new production tubes has some veil and lacks air compared with vi 71 version.

After comparison of two 6N8S tubes, I was back to 1578 Melz.

Everything sound more refined and impactfull and wider and deeper soundstage than both 6N8S tube.

To me 1578 Melz is "holy grail " of 6sn7 tube.

But 6n8s tube named vi71 Nos is a very nice value at 46$ per quad is a steal (best value overall).

I had liked Raytheon Vt231 which cost me 65$ as excellent bargain, but this 6n8s may have gone farther as performance to value.

Thus I had ordered one more quad set of 6n8s tubes just in case.


It is time to summarize the shootout of 6sn7 tubes.


1578 Melz is the King of 6sn7 with nice decay, full bass, sweet treble, widest and deepest soundstage.

TS, Syl, KR, RT and RCA Vt231 are just in second tier but they are all excellent tubes that I can live happily.


6n8s vi71 that I got yesterday is half notch below Vt231s made in 1940s and best value at 46$ per quad.

All 6sn7 tubes made in 1950's are quite good but they have no more room to play in my system.

They will be in in storage until I decide to sell them.
 
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thomask

Well-Known Member
Dec 9, 2018
554
395
75
60
Washington State, US
#60
thomask, what is acid etched date code on the 1578 tube that arrived yesterday? The OTK-73 stamp has nothing to do with the date of manufacture.
I checked acid etched date to find that the lower one was made in 80 and upper one made in 83 not 70's.

But with no faults of sound I will not return it just based upon faulty description of manufacturing date.

Also 6n8s Nos tube has etched date of 12/78.
 

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