Shootout of Nos 6sn7 tubes

highstream

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Nov 16, 2013
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Not sure you're correct about this. The tubes are preamp (gain?) tubes in a Supratek Chardonay preamp. https://1drv.ms/u/s!AqsCKHVTj0ydpkGuRrV4BwVMgWXc?e=KMvFQ6
Since I recall that the gain tubes and cathode followers in my previous PrimaLuna Dialogue preamp could be heard to the tap, I checked some new production 6SN7's I have: the Tung-Sol 6SN7GTB that came with the preamp (early April) and had virtually no use and the Shuguang WE6SN7 I used until the other day. All could be heard through the speaker when tapped. That doesn't mean the Hytron version I wrote about isn't bad. It does sound different through the speaker than the other one when tapped, and *sometimes* when tapped seems prone to extra vibration or something causing the noise I mentioned, that goes on and on. The only other thing I can think of is that the preamp circuit doesn't like the CBS/Hytron GTB, although I wouldn't know why, since it runs well less than max.
 

Lowrider75

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Dec 4, 2019
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All tubes will be heard thru the speakers if tapped (mostly in the gain stage). A microphonic tube when tapped by fingernail or the end of a pencil will ping or ring like a bell and will also decay like an instrument. It may also pick up the sound of tapping on the component close to the tube and will be heard thru the speakers.
If none of the above, enjoy the music.
 
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highstream

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Thanks for clarifying. In my set up, only two of the eight can be heard, the Hytrons. There's not much of a decay on those two, but the pitch between them is very different. One is fairly low, while the one being discussed here is much higher, hollow sounding.

Follow up: The developer of the preamp wrote:
Yes its just normal microphonics. Its amplified by the Chardonnays highish gain. If you use the gain control you can eliminate it. I actually think a bit of microphonics isn’t a bad thing. A lot of NOS are microphonic , some are really bad. The new production Tungsol, Sovtek EH have very rigid internals and don’t ring at all. The DHT tubes are all microphonic , might partly be the magic . Microphonics freaks a lot of audiophiles out, but it doesn’t worry me, tubes are organic and very complicated devices, they do a great job and should be giving a bit of leeway for their characteristics.
 
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Lowrider75

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Dec 4, 2019
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As long as there's no ringing sound between songs or quiet passages, I don't worry about a slightly microphonic tube.

If said tube starts to pick up ambient sound from the room or from the speaker it's time to trash it.
 

highstream

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Nov 16, 2013
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That loud continuous hum I described, which initially occurred on its own and happens most every time I touch the preamp, requires that the unit be turned off to kill. It is apparently sign of maybe a loose or misplaced wire inside. I’ve asked for a replacement (the guy has a bag full).

Follow up (7/30): Turns out the bag doesn't contain any more CBS/Hytrons, or at least not for me. I've been mostly lucky on eBay with older tubes because the sellers have had good testers, but this guy's one didn't test for noise or microphonics. Tubes went back today. The Shuguang WE6SN7's, which are very good, have gone back in.
 
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Jun 30, 2020
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Berlin, Germany
griggaudio.de
Today I finally got around to trying out the NOS (New Old Stock) tubes.

A detailed measurement report was enclosed with each pair (only part of it can be seen in the picture). Even if I don't understand the measured values, I interpret information such as 113% above the target value as positive.



Pair of 6SN7WGTA military goods, new, original packaging, Philips USA = Sylvania

The metal pins are extremely stable.



Pair of RCA 6SN7GT, new, orig.packing, 1950s



The dealer already warned me that, despite the measurements, tubes could be defective. An RCA tube was noisy. And so for now I can only hear hybrid (old and current production). The NOS tubes are plugged into the sound-relevant chassis and have to settle in first. In terms of sound, the very warm timbres are already noticeable. It actually reminds me of a tube radio. :D

 
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Lowrider75

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Dec 4, 2019
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Today I finally got around to trying out the NOS (New Old Stock) tubes.

A detailed measurement report was enclosed with each pair (only part of it can be seen in the picture). Even if I don't understand the measured values, I interpret information such as 113% above the target value as positive.



Pair of 6SN7WGTA military goods, new, original packaging, Philips USA = Sylvania

The metal pins are extremely stable.



Pair of RCA 6SN7GT, new, orig.packing, 1950s



The dealer already warned me that, despite the measurements, tubes could be defective. An RCA tube was noisy. And so for now I can only hear hybrid (old and current production). The NOS tubes are plugged into the sound-relevant chassis and have to settle in first. In terms of sound, the very warm timbres are already noticeable. It actually reminds me of a tube radio. :D


Are those RCA 6SN7GT with grey glass? If so, they were made in the 1940s and sound fantastic.

If the dealer said a tube might be defective, why did you buy them? All tubes should be tested before they are sold.
 
Jun 30, 2020
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Berlin, Germany
griggaudio.de
Are those RCA 6SN7GT with grey glass? If so, they were made in the 1940s and sound fantastic.
Yes the RCA have gray glass. Mine are from the 50s.

If the dealer said a tube might be defective, why did you buy them? All tubes should be tested before they are sold.
The tubes are only measured and not heard. Everything is not a problem. Of course I get a replacement.
 
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highstream

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Nov 16, 2013
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A question about a pair of 6SN7 tubes that aren't matching. I came across two tubes of one of the very best 6SN7's models that I've wanted to try, but normally tend to be relatively costly. These two tubes are being sold separately and inexpensively by the same person. I'm trying to figure out, given their low prices, if they might worth trying to see if they'd at least give the sound quality information I want, or if their specs/construction/quality are too far apart to be of much value for that purpose. They'd go into in a Supratek Chardonnay preamp (has a balance knob). Thanks,

Top D Getter Black Plate - B Used Old Stock
IA: 9 GM: 2.9
This valve:
IA: 10.7 GM: 2.35
IA: 9.7 GM: 2.1

Foil Getter at Base Black Plate - A Used Old Stock
IA: 9 GM: 2.9
This valve:
IA: 7.7 GM: 2.7
IA: 8.2 GM: 2.8
 
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Lowrider75

Member
Dec 4, 2019
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A question about a pair of 6SN7 tubes that aren't matching. I came across two tubes of one of the very best 6SN7's models that I've wanted to try, but normally tend to be relatively costly. These two tubes are being sold separately and inexpensively by the same person. I'm trying to figure out, given their low prices, if they might worth trying to see if they'd at least give the sound quality information I want, or if their specs/construction/quality are too far apart to be of much value for that purpose. They'd go into in a Supratek Chardonnay preamp (has a balance knob). Thanks,

Top D Getter Black Plate - B Used Old Stock
IA: 9 GM: 2.9
This valve:
IA: 10.7 GM: 2.35
IA: 9.7 GM: 2.1

Foil Getter at Base Black Plate - A Used Old Stock
IA: 9 GM: 2.9
This valve:
IA: 7.7 GM: 2.7
IA: 8.2 GM: 2.8

A top getter tube may not match a bottom getter in sonics. If they are from the same generation of manufacture, same factory, same internal tooling then they might match.
Those measurements are close enough for used tubes. Contact the seller. I wouldn't move on those tubes without knowing the year of production.
 

highstream

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Nov 16, 2013
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The seller believes they are both 1959. He also notes that other than the difference in construction, the gain (GM) of the A one is higher than the other. I asked if the meaning of A and B came from the manufacturer, but he says it’s merely their stock designation. Any further thoughts with that info?
 

Mendel

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Feb 14, 2012
100
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368
GTA
The seller believes they are both 1959. He also notes that other than the difference in construction, the gain (GM) of the A one is higher than the other. I asked if the meaning of A and B came from the manufacturer, but he says it’s merely their stock designation. Any further thoughts with that info?

I would not use the tubes in question in a preamp gain stage. They are different construction (top getter and bottom getter) and have different electrical characteristic. I believe you should use matching pairs for your preamp, meaning same make, same construction and similar electrical characteristic.
 
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highstream

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Nov 16, 2013
490
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273
I would not use the tubes in question in a preamp gain stage. They are different construction (top getter and bottom getter) and have different electrical characteristic. I believe you should use matching pairs for your preamp, meaning same make, same construction and similar electrical characteristic.

Mendel, Did you read my OP as to why I was considering these? Just checking.
 

Mendel

Well-Known Member
Feb 14, 2012
100
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368
GTA
Mendel, Did you read my OP as to why I was considering these? Just checking.

I did. You specifically mentioned that they would be used in your Supratek preamp. In my opinion they would not be suitable for that use. Might as well use a Sylvania on one side and an RCA on the other. Just my opinion of course.
 
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Lowrider75

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Dec 4, 2019
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The seller believes they are both 1959. He also notes that other than the difference in construction, the gain (GM) of the A one is higher than the other. I asked if the meaning of A and B came from the manufacturer, but he says it’s merely their stock designation. Any further thoughts with that info?
The seller believes they are both 1959. He also notes that other than the difference in construction, the gain (GM) of the A one is higher than the other. I asked if the meaning of A and B came from the manufacturer, but he says it’s merely their stock designation. Any further thoughts with that info?

I agree with @Mendel. They are not similar tubes. Especially for a preamp gain stage. Pass on these tubes and use Google to look for a matched pair
 

highstream

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Nov 16, 2013
490
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Zalytron. Don't come up often, except at Upscale Audio for $200 each.
 

Lowrider75

Member
Dec 4, 2019
63
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Zalytron. Don't come up often, except at Upscale Audio for $200 each.
Zalytron did not manufacture tubes. They rebranded US tubes, so there's little chance of these tubes performing the same. Also, two different designs. A Zalytron matched pair would be a different story..
 

highstream

Well-Known Member
Nov 16, 2013
490
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Thanks for the advice. I read someone who seemed to know say (not Upscale) that the Zalytron were the best of the best CBS/Hytrons. Since I like the tone of the latter, I’ve been watching the market (as well as for one or two other 6SN7 types).
 

Lowrider75

Member
Dec 4, 2019
63
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Thanks for the advice. I read someone who seemed to know say (not Upscale) that the Zalytron were the best of the best CBS/Hytrons. Since I like the tone of the latter, I’ve been watching the market (as well as for one or two other 6SN7 types).
They're high quality US tubes, but rebranded.
 

thomask

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Dec 9, 2018
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Washington State, US
Mendel, Did you read my OP as to why I was considering these? Just checking.

I would not waste time to consider the mismatched tubes made in 1959.

After having gone through more than 16 6sn7 Nos tubes last 6 months.

My recommendation is

If you like full bass and wide and deep soundstage , then you shall try Melz 1578.

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

This dealer replaced a noisy tube quick and easy.

Melz 1578 had been staying in Line Magnetic 508 amp for the last 3 months.

Sylvania vt 231, Kenrad vt231, RCA vt 231 are recommended if they are priced under 160$ pair with good measurement.

I am happy with Kenrad vt231 at gain stage and Sylvania vt 231 at buffer stage on Schitt Freya Pre.
 
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