Shootout of Nos 6sn7 tubes

I know what you’re saying. The design of my amp with the extra tube stage allows me to add additional flavours. The Sylvania GTA Angled Plates have high-end energy that works well with female vocals. No sibilance, but crisp mids and highs.

@lowrider57

It is good to hear that you enjoy 1578 tube that I had recommend to you.

You also had gone through many 6n7 tubes.

1578 has the best bass, widest and deepest soundstage and sweet treble.

The only drawback of 1578 is that when I play lady vocal, I prefer Sylvania or TS vt231 due to more details

I’m loving my new 1578’s that shkong recommended (1980). They’re in the gain stage of my Atma-sphere S-30 and they sound as good if not better than TS Round Plates. The low-end is deep and tight with liquid mids, and the highs are extended yet extremely smooth. Clear and quiet, revealing the softest sounds in a deep and wide soundstage.
Right out of the box (there is no box, they’re in rolls) music had the greatest sense of realism I’ve heard in my system. They’re so transparent and tonally accurate that the tube search for this amp is over.

There are 6 input tubes in the amp; each channel uses two tubes in the gain stage plus the phase inverter (driver). The 2nd gain tube is a Sylvania GTB, the driver is a Sylvania GTA angled plate.

Other 6SN7s I’ve tried in my amp or preamp are:
Sylvania VT-231, which does everything well but is weak in the bass.
Sylvania 1950s GT Staggered plates
Sylvania 6SN7WGT
KR VT-231 WWII
RCA VT-231 & GT black glass
RCA GTB 1950s Silver label
T-S Black Oval Plates WWII
T-S GTB 1950s Triangular plates
Russian 1960s 6H8C black base

I’m sure I’m forgetting some.

https://www.ebay.com/itm/Raytheon-JAN-CRP-6SN7GT-VT-231-Vacuum-Tubes-1944-Balanced-Matched-on-Hickok/392787627010?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

I am listening to Jazz music including " I left my heart in San Francisco" through Raytheon vt231 that cost me 65$ from Ebay auction.

I had lived in Berkeley hill overlooking Golden Gate bridge from 1984 to 1987.

This tube does not sound pure as Syl,TS, RCA vt231 with some lively edge.

But Jazz music sound more realistic through this Raytheon tube.

It is really fun to go through nice 6sn7 tubes.

Although 1578 give nice bass and soundstage, but it sound boring with Jazz vocal music due to closed in treble.

@zipost


I do not think TS bgrp is bad tube.

But Sylvania vt231 also give spooky details and transparent window as well as TS bgrp but at one third cost.

Law of diminishing return apply heavily in audio.

I have pair of Telefuken 12AX7 tubes whose lively and nuanced details I enjoy.

Thus I could understand why you like Telfuken 6sn7 so much.


For most of people, they do not need to go for TS bgrp to get nice lady vocal sound.

They can be happy with Sylvaniia vt231 which I had been happy for 2 years in LM 508 amp.

I am listening to Beethoven Piano concerto using 1578.

Piano sound so natural through 1578 that my judgement on 1578 as "Holy grail of 6sn7" could be justified.

But choice of tube is dependent on system and personal taste.

Thus I understand that other people may have different opinion.

Thomas

shkong78... i disagree with you on the Tungsol Round Plate black glass.  Not an overhyped tubes,  ‘One of The Best ‘ if not ‘ The Best ‘ for single ended triode amps for vocal! 

@ testpilot

Two pairs of 1578 sounds clean without noise or hum and one pair give some high frequency noise before full 20 minutes warmup.

Thus I am happy with my three pairs of 1578 made in 1980 and 1983.

I agree with you that TS bgrp is overhyped.

One can get pair of Sylvania vt231 which sound close to TS bgrp around 150$.


But 1578 is not for everyone.

Its balance is bass heavy and closed in at treble compared with Syl vt231.

The Melz 1578 should be dead quiet with no buzzing or hum.  If you want the best of the best 1578 look for a pair manufactured in the 70's.  Tung sol black glass round plates are over rated (for their asking price) and their price is due to their rarity.

If you want to experience 1578 tube, then I recommend this dealer who sent the tube very fast.

https://www.ebay.com/itm/Matched-pair-Extremely-rare-1578-6N8S-audiophile-6H8S-6SN7-Metal-base/273874731266


It give some hum and noise at the start but with burning in for 20 hours,  those noise had been almost gone.

Very informative post, thank you!I have a Line Magnetic 508 as well, so considering the MELZ 1578. There appear to be a bunch of these online now with prices all over the map. How do I know which "1578" tubes to buy? Is there something specific I'm looking for to know I am getting the "right" 1578 tubes?

I had done second sets of shootout

"Autumn Leaves" by Eva Cassidy
""Caravan" in the Still Harry Album.
’" You ll never find man" in Ice Age soundtrack
and some K pop

1. Shuagang Black 181Z

I got this tube upon reading some raved review that this one sounds better than Nos tubes.

But after comparing this one with Sylvania vt231, I found this one lacking details and transparency compared with Syl vt231 while it sound warm and organic.

i had done shootout with other tubes again this time.

It is just above average in detail, transparency, dynamics.

But it sounds balanced and musical with deep soundstage.

Overall it is a pretty good tube, but I will not buy at 120$ again.


2. RCA gray bottle made in 50’s

This RCA sound similar to RCA vt 231.

But RCA vt231 is more transparent and more detailed than RCA gray bottel.

Gray bottle has very good bass and macro dynamics also with nice decay thus it also sound similar to 1587 Melz.

This make overall sound round and warm almost analog like.

Some people may find this tube boring while other people may like this.


3. 1578 Melz

After listening to RCA gray bottle, I switch to 1578 Melz made in 1980 for comparison.

They sound similar with nice bass, decay and wide soundstage.

But 1578 is slightly better than RCA gray bottle on every respect and more air than RCA gb.

1578 give best dynamics and widest and deepest soundstage while it may sound little bit closed in compared with Syl Vt231.

This one will be good for hard rock, metal music and big orchestral music.


To me this is the "Holy Grail" of 6sn7 tubes.

I had bought three pairs of 1578( two made in 1980 and one made in 1983).



4. Sylvania GTB Tall bottle made in 1955

This one sound very similar to "Bad boy " version made in 1952 with excellent bass and macrodynamics.

It also has some lively treble but overall kind of mediocre.

Not a bad tube but not excellent as Vt 231s.


5. Sylvania WGT brown base made in 50’s.

I got three tubes at 65$ including shipping and tax from Ebay.

It could be hit or miss to buy Nos tubes from Ebay.

This one is clearly big hit.

This tube give lively details, good speed and transparecy.

It sounds almost like Raytheon VT 231 at much lower cost to me.




DetailsTransparenSpeedTonalityTreble ExTreble ClMi DynMac DynS. DepthS. widthNet costTotal costTS bgrp9.5​9.5​10​9​9.5​10​9​8​9.5​9​575​93​RCA vt2319​9​8.5​9.5​9.5​9​8.5​9​8.5​10​89​90.5​KR vt2319​9​9​10​8.5​8​9​10​9​9​83​90.5​RT vt2319​9​9​8.5​9​8.5​9​9​8.5​9​92​88.5​Syl vt10​10​9.5​8​10​10​9.5​7.5​9​9​100​92.5​Bad boy8​7.5​8.5​9​7.5​8.5​8.5​9​8.5​9​215​84​1578​8.5​8​9​9​8​9​9.5​11​10​10.5​250​93.5​S 181z8​8.5​8​9​8.5​9​8.5​8​9​8.5​120​85​RCA gr8​7.5​8​9​7.5​8​8.5​9.5​9​10​105​84.5​Syl Tall8.5​8​8.5​8​8​8​8​9​8​8.5​108​82.5​Syl Wgt9​9​9​9​9​8.5​9​8​8.5​8.5​45​87.5​Treble Ex means extensionTreble Cl means clarity
https://www.head-fi.org/threads/shootout-of-nos-6sn7-tubes.932083/

So far 1578 Melz got the best score just above TS bgrp at less than half cost.

All vt231 tubes made in 40’s are excllent.

Syl Wgt brown base was the best among the tubes made in 50’s at only 45$ per pair.

I am back to RCA vt231 in Line Magnetic 508 amp which make me comfortable with lush and warm sound but also with nice bass.


f I want explosive bass or widest and deepest soundstage, I play 1578 Melz.

Ken rad vt 231 has nice bass with more air than 1578

If I want utmost details , then I play Sylvania vt231.

If i want see through transparency, then I play TS bgrp

For lush and warm sound, I would go for RCA vt231.

Raytheon Vt231 is also good choice midway between Syl and Rca.

With taking turns on 6 sets of 6sn7 tubes, it is like having 6 different set of preamp.

@ jtcf

If you are bass or soundstage freak then you  may go for 1578 Melz.

Ken rad vt 231 is also pretty good choice all around.

If you care about details or transparency, then go for Sylvania vt231.

For lush and warm sound, go for RCA vt231.

Raytheon Vt231 is also good choice midway between Syl and Rca.

Black Sabbath and the 1578s seem to get along well. 

Interesting thread!I recently found a seller on Esty and ordered a few GE,Tung Sol,RCA to try for the input tube in my amp.All short bottles, black plates,black bases.Those RCAs are really dynamic with excellent textured bass.A nice surprise:-)The TSs have a wonderful midrange but not much detail top or bottom.The GEs are both lush and detailed,really nice.These all averaged around $20 apiece so not too expensive to experiment with.

I needed to replace the Sofia Blue which I really liked for almost a year.They aren't noisy or anything,but somehow lost their tone and sounded flat.Just not worth the price if they have to be replaced often.

I am back to Kenrad vt 231 playing "Autumn Leaves and Songbird" by Eva Cassidy.

Although 1578 Melz give best bass, decay, widest and deepest soundstage, it has two drawbacks.

The first one is slight hum and high frequency noise which is almost gone after 20 minutes warmup while KR is dead quiet without warmup.

The second one is that its treble can sound closed in slightly lacking air or sparkle.

KR vt 231 sounds very similar to 1578 but with slight more sparkle.

Thus I prefer KR to 1578 in playing lady vocal music like Eva Cassidy while I prefer 1578 in playing orchestral music.


I will take turns at tubes to taste different flavor depending on music genre and my mood.

But be sure to use socket saver if you roll tube often.

https://www.ebay.com/itm/CED-P-ST8-1000-VACUUM-TUBE-8-PIN-OCTAL-SOCKET-SAVER-for-6L6-6V6-6SN7-EL34/150688246271?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

I have three pairs of 1578.

Funny thing is that both pairs made in 1980 has some hum and high frequency noise

But one pair made in 1983 sounds fine and has filthy bass as described by "big_greg".

I am listening to "The Wall" .

I am happy that Line Magnetic 508 fitted with 1578 can drive my speaker Lansche 4.1 with such full force and control of bass.

It also give widest and deepest soundstage with holographic layering in my listening room so far.

If you are bass freak or soundstage mania, then you shall try 1578 Melz

Congratulation big_greg

But I have a problem with one of tube.

KR is dead quiet, but 1578 has hum and high frequency noise until 20 minutes warmup.

I am going to wait few more days before I contact the dealer.

I bought a pair of the Melz 1578 from the seller @shkong78 recommended for my Modwright LS 100.  I played them for a while last night and they sounded really good right out of the box (I had the LS 100 in HTBP mode for about an hour to get them warmed up, watching TV).

They are detailed, dynamic, and the bass is prominent with a texture that I have not heard in my system before.  Pithy might be a good description of the sound of the bass.  The soundstage was expanded and there seemed to be more separation between the instruments.  I can't wait for them to break in a little more. 

They were one of the best bang for the buck upgrades I've made to my system.  I've used Shuguang CV-181, the stock Tung-Sol tubes, Sylvania Chrome Domes, Sylvania 6SN7GTA "tall boys", and Sophia Electric clear and blue tubes.  The 1578s were the best by far.

https://www.ebay.com/itm/Matched-pa...-audiophile-6H8S-6SN7-Metal-base/273874731266

I had got new one from  this dealer.

It took only a week from Russia to get to Washington State.

One of 1578 tube need more than 20 minutes warmup before some high frequency noise is gone..

After playing one hour it seems to be fine

Good to see the posts above. In particular, the notes about the Melz 1578. Those were impossible to find for a while but now it looks like a batch has shown up from somewhere and there are multiple dealers selling them.

Please - those of you who are trying them out - please continue to share your impressions and also your trusted sellers with best price and delivery.

Best regards,

Markus

@zipost


Thanks for your recommendation.

But there is no best thing for everybody.

It will depend on system and personal taste.

Also some audio gadgets are overpriced with hype or due to law of diminishing return.

I found Telefunken 6sn7 is listed at 1,600$ from Italy


I have more than enough 6sn7(17 different kinds total 70 tubes)

Thus I am going to stop purchase of more 6sn7 tubes.

Since my speakers with plasma tweeter and Dave and HMS is on the neutral or somewhat analytical side ( not warm or bloated) , my preference without considering cost is


1. 1578 Melz
2. TS bgrp
3. Syl vt231
4. Kenrad vt231 bg
5. Raytheon vt231
6. RCA vt231 gray bottle
7 6n8s made in 1978
8. Syl 1952 "Bad boy" three hole.
9 Syl 6sn7w brown base
10 Syl gtb tall bottle made in 1955
11 RCA gray bottle
12 Shuguang Treasure CV181-Z ( New production)
14.. Tungsol gtb tall bottle made in 1950’s
15. Amperex GTB
16. New production 6n8s ( stock tube of Schitt Freya)
17. New production Tungsol GTB

shkong78..... when you get a chance, i strongly recommend the Telefunken 6sn7. With all the characteristics you described and your listening styles the Telefunken might be your cup of tea!

here is my lists of 6sn7 in particular order:

telefunken 6h8c 6sn7
GEC 1988 Metal base 6sn7
Amperex miniwatts ecc32
tungsol Round plates
Tungsol 6f8g Round plates w/adaptor
Sylvania metal base
Kenrad black Round plate
Metz Russian

Hands down the telefunken 6h8c my go-to for 6sn7

I do not have  Sylvania 6SN7W metal base.

But who heard the tube mentioned it is little bit overhyped.

I have  Sylvania 6SN7W brown base which sounds lively with good details but not in same class as 1578.

If is better to choose 6sn7 tube based upon what you want to improve.


The advantage of 1578 is nice timber,  bass, decay and widest and deepest soundstage.

If you want to go for utmost  transparency and details, then you had better get Sylvania vt231.

If you want lush and warm sound, then go for RCA vt231 grey bottle.

Just my 2 cent

Thomas

How would you compare Melz 1578 and Sylvania 6SN7W metal base?
I was going to purchase a pair of 6SN7 tubes for my Supratek Cortese preamp and was considering the Sylvania as the one till Melz discussion here.

The RCA red bass must sound terrific in your system.

I used to use Mullard ECC35 for more than one year.

But about 3 weeks ago I switched to RCA 5691 red bass which give more details and deep bass than ECC35.

OP,  your amp uses one 6SL7 and two 6SN7s, yes? I believe the 6SN7 would be the phase inverters. Correct me if I'm wrong.
I assume you've tried rolling the 6SL7. What tube works for you in this position?

First impression of the 1578 - wow! Looking forward to see how they sound after a little burn in. 

About 2 hours ago, I got delivery of another 1678 Melz tube from Russia after one week from placing order.

Very fast shipping.

I had not got tubes from Ukraine that I ordered 5 weeks ago.

It was made in 1980 and looks clean as Nos tube.

After playing demagnetization track, I am listening to familiar music to me.

"Thriller" by MJ sounds spooky with deep and full bass, wide and deep soundstage.

Its bass, decay and soundstage is just beyond any other 6sn7 tubes.

But people may get the impression that it is bass heavy.

Now I have three pairs of 1587 Melz tubes and eight 6n8s tubes, I am going to stop shopping of 6sn7 tubes.

After being back from Kr vt231 this morning, I found that 1578 has more body and decay while KR give almost same amount of details as 1578.

i also had get delivery of 1578 from Russia this afternoon.

After I get it, I will give a try to compare with other two 1578 that I have.

Good luck to you!

The 6n8s made in 1978 that I had tried this week is real deal.

I ordered four more of them and two of them is staying in Freya.

@shkong78 I ordered a pair of those 1578's last Saturday and they just showed up on my doorstep.  I will give them a try tonight or tomorrow.  I was surprised they got here so fast.

I'm surprised you liked the 6N8S so much.  I thought about getting a pair, but everything I read about them was negative.  I saw some selling for $4.50 each.

Looking forward to trying the 1578's.  Thanks for the information about them.

I also have two pair of GE (Rca) gray bottle which sound warm and lush.

But I prefer to take turns between the tubes.

It is more economical way to get new flavor than changing pre amp or cable rolling.

NOS GEs

are 

my

current

faves

after 

trying various others in my Freya and Had SEP amp. I also tried double spacing this post to see if it works for me and yeah, it's kinda lame.

After listening to 6n8s tube made in 1978 for several hours, I am back to Kenrad vt 231.

KR also has nice bass with sweet and refined atmostphere.

Definitely KR vt231 is at least half notch or even one notch above 6n8s .

Now I have 16 different variants of 6sn7 tubess.

After changing tube, sound also change as if new pre is being used.

It is like tasting various wines or coffees.

But if you do lot of tube rolling, be sure to use socket saver.

https://www.ebay.com/itm/CED-P-ST8-1000-VACUUM-TUBE-8-PIN-OCTAL-SOCKET-SAVER-for-6L6-6V6-6SN7-EL34/150688246271?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

If you look for etched sign in the middle of tube, then you can find the year like 80 or so.

shkong78,
 
I have a pair of Melz 1578 tubes. Can you please tell me how to check for date of manufacturing?

QUAD FOUR Matched Balanced Russian 6N8S 6SN7 double triode TUBE NEW NOS | eBay

After listening to 1578 Melz, I am back to Nos 6n8s tube made in 1978 that I got quad at 46$.

By the way i got my first serious audio system on 1978.

What a coincidence.

This is a steal.

It sound musical with good balance of full bass and sweet treble.

Jump at it before they run out of this batch.

Someone tipped me about the manufacturing date on the etched note of the tube.

The 1578 that I got was made in 1980.

The 1578 that I got was made in 1983 not 70's.

8n6s Nos tube was made in 12/78.


Even without 1578 notation, some tubes are still pretty good for the price.

I think you are correct, there is a 1578

What you got is just regular Melz 6n8s tube. 

I believe the stamp of 1578 faded, if you look at the photos, the construction it looks and even has the OTK stamp, but I don't intend to argue, if you think I did not get Melz 1578 that's fine, for all purposes you could be right and I could be wrong.thank you for replying

https://lh3.googleusercontent.com/pw/ACtC-3c7y0kfiPiPhcKAedF_b8ONC22aHKTsDheEd51FmF8Omwv_hVyEck_W852...

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.

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%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649 

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

https://www.ebay.com/itm/QUAD-FOUR-Matched-Balanced-Russian-6N8S-6SN7-double-triode-TUBE-NEW-NOS/312402083888?ssPageName=STRK%3AMEBIDX%3AIT&_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.

https://lh3.googleusercontent.com/pw/ACtC-3d6V72LNg7nKRCgdFBsk8dIbfv8BHalFGAY4vgIb5epdveAY00rkFhkpOT...

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 finish 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.

Luisma

What you got is just regular Melz 6n8s tube.

Melz 1578 is notation for quality certification for military use and nuclear plant.

you should try the tall-bottle (metal or plastic/6SN7W or A),

Thanks but I think that is unobtanium

But I think you did not get Melz 1578 at 10$ per tube.

don't know why you would have to doubt my statement but that's ok, 2 years ago the Melz were not in the demand they are today, as a matter of fact there are more on Ebay today that back then

@luisma

Sorry to  hear your bad experience.

But I think you did not get Melz 1578 at 10$ per tube.

Melz1578 is a special one which cost 100$ per tube or more.

I am enjoying Grieg Piano Concerto  through Melz 1578 now.

I can definitely claim this is the best 6sn7 tube so far.

ButI do not mind using other excellent vt 231s to taste different flavor from time to time.

luisma- If you like the short-bottle, 6SN7W: you should try the tall-bottle (metal or plastic/6SN7W or A), if you haven't already.      I used those, for around 15 years (in concert with my TSRPs, as they seemed to provide better Bass slam, as well as sweeter highs, than the short ones, in my amps.      Same wonderful ambiance recovery and over-all, uncolored tonality.

I tried the Melz’s 2 years ago, these run hot on my Atmasphere MP-3, bought 2 pairs, 1 tube of each pair died after a few hours, they weren’t that special IMO on my gear, I remember not much bass and very bright, but the RCA red base that it is supposed to be very good too wasn’t that special either. From most tubes I tried Raytheon gray glass and short bottle Sylvania 6SN7W were among the best, I settled for new production Chinese CV181-Z. Let me post a picture of the remaining Melz.

https://www.dropbox.com/sh/x3dhhpbqoc2qjgq/AAC69xScWKrlfDY4aN0tHKhLa?dl=0
Thank you to the OP for taking the time to go over this

Oh I paid $10 for each Melz, there are plenty of old 6N8S like the Melz but black bases OTK, although not the same quality as the Melz should be very close and cheaper.

https://www.ebay.com/itm/Raytheon-JAN-CRP-6SN7GT-VT-231-Vacuum-Tubes-1944-Balanced-Matched-on-Hickok/392787627010?ssPageName=STRK%3AMEBIDX%3AIT&_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.

1578 tube made in 1970's will be delivered next Wednesday.

I will find out!

But it is possible that tube made in 80's work better with my system.

If you like the Melz 1578 from the 80s. Just wait until you get a ear full 
of a pair from the early 70s.  They are that much better..