Help me choose a couple of 6N8P/6SN7

[releone71]

I have a Chinese SE amp with a couple of Psvane branded KT88s. The sound is very articulate and rich in detail but, as usual with Chinese tubes, a bit too bright for my taste. I'd like to replace the drivers, which are 6N8P from Shuguang's factory, with something that plays warmer and rounded, but I don't want to afford the cost of vintage tubes like Sylvania & Co.. As I have no experience with 6N8P/6SN7, I'd like to have some help from you on the current models available from the most common brands like Sovtek, Electro Harmonix, JJ Tesla, Tung Sol, etc.. Thank you very much.

 

[FlaCharlie]

I'd like to replace the drivers, which are 6N8P from Shuguang's factory, with something that plays warmer and rounded, but I don't want to afford the cost of vintage tubes like Sylvania & Co.. As I have no experience with 6N8P/6SN7, I'd like to have some help from you on the current models available from the most common brands like Sovtek, Electro Harmonix, JJ Tesla, Tung Sol, etc.. Thank you very much.

The big dealers sell NOS American 6SN7s for $20. The one near me calls the ones at that price "generic", so they obviously charge more for some others. I'm not a 6SN7 connoisseur so I don't know which ones they might consider the premium brands. It looks like the current production versions are in the same ballpark in terms of price (JJ $16, Sovtec $18, EH $20, Tung Sol $24) Quality? I don't know.

Another option would be to add a small 12.6v filament transformer and use NOS 12SN7s, which are only $5 each with, apparently, no restriction on brands. As an added benefit, this will reduce the strain on your power transformer and it will run cooler. That's a good thing since the PTs on these cheap Chinese amps seem to be one of their weak points.

Or, if you want genuine NOS Sylvania for cheap you can replace the octal sockets with loctals and use the 7N7 which sells for $10. Same tube, same filament voltage, different base. Or use the loctal 12v version, the 14N7, which sell for $7. All loctal tubes, regardless of how they are branded, were made by Sylvania.

 

[Lavane]

New manufacture I like Tung Sol. They take about 30 or so hours to settle in. Most of the 6sn7's I've tried took some hours to burn in and sound good.

 

[releone71]

New manufacture I like Tung Sol.

Thanks. I like them too. I usually install TS or JJ in my electronics, but my experience is limited to the ECC8x family of valves and EL34, hence my question. I have several electronics, stereo and bass heads, all with ECC8x and EL34, so this is my first amp with KT88 + 6SN7. Do you confirm TS 6SN7s have the same balanced sound as their other tubes?

 

[Lavane]

They sound well balanced to me once burned in. I've tried JJ's, Sovtek and a few others and came back to the TS's. There are better if you want to shell out the $$.

 

[releone71]

The big dealers sell NOS American 6SN7s for $20. The one near me calls the ones at that price "generic", so they obviously charge more for some others. I'm not a 6SN7 connoisseur so I don't know which ones they might consider the premium brands. It looks like the current production versions are in the same ballpark in terms of price (JJ $16, Sovtec $18, EH $20, Tung Sol $24) Quality? I don't know.

Thanks for all the hints. Just another question, as I've read an old post from you regarding the opportunity to replace the 5Z3 rectifier. The one in my amp is a Shuguang 5Z3PAT and they state it's compatible with the 5U4G or CV841. Do you confirm? Any brand recommended? Thanks.

 

[Lavane]

If I remember right, the 5Z3PAT is not the same as a 5Z3. Depending on the circuit used a 5u4 can be used for a 5Z3, but not the 5Z3PAT. The 5Z3PAT you have has a four pin base, right?

 

[FlaCharlie]

If I remember right, the 5Z3PAT is not the same as a 5Z3. Depending on the circuit used a 5u4 can be used for a 5Z3, but not the 5Z3PAT. The 5Z3PAT you have has a four pin base, right?

The Chinese use of the 5Z3 number creates a lot of confusion.

The 5Z3, with no suffix, is an old American 4 pin rectifier that does not have an octal base. The Chinese 5Z3 versions that I've heard of - the 5Z3P and 5Z3PA - have four pins but they use an octal base. I've never heard of the version with the "T" at the end and I couldn't find a data sheet for it.

Electrically, the American 5Z3 is equivalent to the 5U4G. The 5U4GB is a heavy duty version. Here's a data sheet for the American 5Z3, 5U4G and 5X4G. Notice that the pinouts are all different. The 5U4G and the 5X4G both have octal bases but not the 5Z3.

https://tubedata.altanatubes.com.br/sheets/127/5/5Z3.pdf

Thanks for all the hints. Just another question, as I've read an old post from you regarding the opportunity to replace the 5Z3 rectifier. The one in my amp is a Shuguang 5Z3PAT and they state it's compatible with the 5U4G or CV841. Do you confirm? Any brand recommended? Thanks.

The 5U4GB is a drop in replacement for the 5Z3PA and 5Z3P, which are both made by Shuguang. If your amp has an octal rectifier socket the 5U4GB will work fine. Another good sub would be the 5V3A. Same pinout and they all run at 3A of heater current. You could also use a 5AR4, which uses less heater current and offers a slow start.

The problem with the 5Z3 is that the data sheet lists a maximum first cap of only 4uf and the Chinese amps often use much higher values. This can lead to rectifier arcing and failures.

Check your amp to see what the value of the first cap after the rectifier is. The 5U4GB is rated at 40uf but using a 47uf, which is a common size, is OK since your amp probably uses less current that the 5U4GB can handle. If your amp has a larger first cap then replacing it with a high quality 47uf is a good idea.

The NOS American 5U4GBs are all very stout tubes so any brand should do fine. Strong testing used examples are fine too.

 

[releone71]

The Chinese use of the 5Z3 number creates a lot of confusion.

The 5Z3, with no suffix, is an old American 4 pin rectifier that does not have an octal base. The Chinese 5Z3 versions that I've heard of - the 5Z3P and 5Z3PA - have four pins but they use an octal base. I've never heard of the version with the "T" at the end and I couldn't find a data sheet for it.

Electrically, the American 5Z3 is equivalent to the 5U4G. The 5U4GB is a heavy duty version. Here's a data sheet for the American 5Z3, 5U4G and 5X4G. Notice that the pinouts are all different. The 5U4G and the 5X4G both have octal bases but not the 5Z3.

https://tubedata.altanatubes.com.br/sheets/127/5/5Z3.pdf


The 5U4GB is a drop in replacement for the 5Z3PA and 5Z3P, which are both made by Shuguang. If your amp has an octal rectifier socket the 5U4GB will work fine. Another good sub would be the 5V3A. Same pinout and they all run at 3A of heater current. You could also use a 5AR4, which uses less heater current and offers a slow start.

The problem with the 5Z3 is that the data sheet lists a maximum first cap of only 4uf and the Chinese amps often use much higher values. This can lead to rectifier arcing and failures.

Check your amp to see what the value of the first cap after the rectifier is. The 5U4GB is rated at 40uf but using a 47uf, which is a common size, is OK since your amp probably uses less current that the 5U4GB can handle. If your amp has a larger first cap then replacing it with a high quality 47uf is a good idea.

The NOS American 5U4GBs are all very stout tubes so any brand should do fine. Strong testing used examples are fine too.

Thank you very much! Yes, I confirm the rectifier has four pins in an octal base. The datasheet from Shuguang states: 5Z3PAT (5Z3P) Compatible with: 5U4G and CV841. Here is the link to the .pdf: https://www.google.it/url?sa=t&source=web&rct=j&url=http://analogmetric.com/download/Shuguang%20Beijing%20Vacuum%20Tube%20Datasheet%20Analog%20Metric%20Limited.pdf&ved=2ahUKEwjN5MeyrrXkAhUQcBQKHaXVBOwQFjAOegQIBRAI&usg=AOvVaw08Ye9LUic3xCGKPYB6lu0E
I will check the cap. Any suggestion for a quality replacement?
Finally, I have the opportunity to put my hands over a NOS NIB Westinghouse 5U4GB locally.

 

[FlaCharlie]

Since I mentioned "big dealers" here are some links. I have no affiliation other than being a customer.

I live about 25 minutes from Radio Electric Supply so I've been there many times. ESRC is located in Orlando, which is about 2+ hours south. They both ship worldwide. Some prices at ESRC are a bit lower but Radio Electric will match prices if you just ask. Both of these outfits have huge warehouses with many millions of tubes.

Radio Electric Supply: https://vacuumtubes.net/prices.htm
ESRC: http://www.esrcvacuumtubes.com

I always recommend checking their prices first when you're looking for tubes. Both of them mostly stock NOS American and European tubes.

 

[FlaCharlie]

For caps any of the major brands (Nichicon, Panasonic, Cornell-Dublier etc) are good. Get caps rated at 105 degrees for 10,000 hours. Voltage needs to be the same or higher than the ones you replace. Also check the dimensions to make sure they'll fit.

I suggest buying from a major supplier, not eBay, to make sure you don't get a counterfeit. Not sure who the major suppliers are in Europe. In the US, I usually use Digi-Key since they will ship for free under certain circumstances. This does not apply to foreign shipments though. Mouser is another major supplier.

For anyone in the US or Canada, here's the scoop on free shipping from Digi-Key. Helps out a lot, especially on small parts orders.

http://www.audiokarma.org/forums/in...hipping-on-parts-orders.739513/#post-10018562

 

[releone71]

Mouser and DK are very efficient. I've purchased several components from them in the past. Anyway it won't be difficult to find some good Elna 105° locally. Thanks!

 

[FlaCharlie]

Finally, I have the opportunity to put my hands over a NOS NIB Westinghouse 5U4GB locally.

I don't think Westinghouse actually manufactured those. Maybe I'm wrong but all the Westinghouse tubes I've seen were manufactured by someone else. If it's American and not too expensive it should be good. Just don't pay silly prices. 5U4GBs are very common since a lot of TVs used them. Used ones almost always test like new. I've also seen some Japanese tubes branded Westinghouse but not 5U4GBs. The Japanese tubes, in general, also have a good reputation.

 

[maxhifi]

I don't think Westinghouse actually manufactured those. Maybe I'm wrong but all the Westinghouse tubes I've seen were manufactured by someone else. If it's American and not too expensive it should be good. Just don't pay silly prices. 5U4GBs are very common since a lot of TVs used them. Used ones almost always test like new. I've also seen some Japanese tubes branded Westinghouse but not 5U4GBs. The Japanese tubes, in general, also have a good reputation.

Westinghouse not only made tubes, but they also invented some famous audio types, for example, the 8417, and the 7591. Later on, they did rebrand a lot of other tubes as Westinghouse, so I can see the confusion.

 

[FlaCharlie]

Westinghouse not only made tubes, but they also invented some famous audio types, for example, the 8417, and the 7591. Later on, they did rebrand a lot of other tubes as Westinghouse, so I can see the confusion.

Ahh, yes, I forgot about the 7591. I should have remembered since I have some amps with them. Doh!

 

[releone71]

If it's American and not too expensive it should be good. Just don't pay silly prices.

I can read by the pictures "MADE IN USA EXPORT" printed on the glass. The seller has two units, €39.00 each.

P.S.: thank you AK management for adding the "O" I missed when I typed the title.

 

[FlaCharlie]

I can read by the pictures "MADE IN USA EXPORT" printed on the glass. The seller has two units, €39.00 each.

That seems expensive to me (equivalent to $43 US) since the dealers I mentioned sell them for $15 but who knows how much shipping to Italy would be so maybe that's not too crazy.

I'm totally unfamiliar with the market for NOS US tubes in Europe. If European tubes are cheaper there than here you might find a better deal on some strong used Mullard or Amperex 5AR4s.

 

[releone71]

That seems expensive to me (equivalent to $43 US) since the dealers I mentioned sell them for $15 but who knows how much shipping to Italy would be so maybe that's not too crazy.

I'm totally unfamiliar with the market for NOS US tubes in Europe. If European tubes are cheaper there than here you might find a better deal on some strong used Mullard or Amperex 5AR4s.

Well, the stocks are not the same as in the USA here in Europe. Don't think a German or Dutch tube from the golden era is less expensive here just because they are European made. Even local production from FIVRE is very expensive. It's a matter of rarity. And the production from the EI plant in Nis former Yugoslavia too. The price for that 5U4G is not bad, considering it's an American NOS NIB. Same seller: 65 Euros for a 5Z3 from Marconi Italy!

 

[Lavane]

The 5AR4 would be my choice if you don't need more than a 2.5 amp draw. Less voltage sag and a slow start.

 

[Brice]

They sound well balanced to me once burned in. I've tried JJ's, Sovtek and a few others and came back to the TS's. There are better if you want to shell out the $$.

I agree.
I've tried the new TS and they are not bad at all. Of course a vintage one is way better, but as new production, I could live with it.
You can still find decent tested one, OS (not NOS) on the evil site for almost the same price.