Finding the right 12ax7 for a Bellari VP129

[gloomrider]

Inspired by this (http://www.stevehoffman.tv/forums/showpost.php?p=2425882&postcount=77) post, I have been trying different tubes in the Bellari. What I have tried so far:


Ruby 12AX7A (comes with Bellari, made in China)
Sovtek 12AX7LPS
JJ/Tesla ECC83
Tung-Sol New Production 12AX7
Ei 12AX7EG
Mullard New Production 12AX7 (Groove Tubes, made in Russia)
JAN Sylvania 12AX7WA (NOS)
Tung-Sol 12AX7A (Made in U.S.A, NOS)


I was really in love with the JAN Sylvania until I got that Tung-Sol (USA) tube on Friday. I am just stunned how much of a difference it has made. I came across this (http://www.guitaramplifierblueprinting.com/12ax7.html) that explains a bit more about the relative benefit of old NOS tubes and just how inferior most new production tubes are by comparison. My own findings were quite similar, though finding a NOS Mullard Box Anode is an expensive proposition, so I passed. :angel:

As the author of the original post pointed out, I would probably still take the JJ over the Ruby if those were the only two choices. But wow, do those old USA NOS tubes sound good!

[Toka]

The linked article astutely points out that guitar amps are much harder to deal with concerning different tubes, so the need for NOS there is much more apparent. Still, you found good sound, and thats the important part! :righton:

[XMIAudioTech]

Sovtek 12AX7LPS
Tung-Sol New Production 12AX7
Mullard New Production 12AX7 (Groove Tubes, made in Russia)

FWIW, these three are the exact same tube just with different brand names on them (New Sensor owns all three brand names, and the tube comes from the same factory)

Have you tried a Telefunken smooth or ribbed plate? or a NOS GE Owensboro?

-Aaron

[gloomrider]

FWIW, these three are the exact same tube just with different brand names on them (New Sensor owns all three brand names, and the tube comes from the same factory)

Have you tried a Telefunken smooth or ribbed plate? or a NOS GE Owensboro?

-Aaron

I'm not familiar with the Owensboro (KY?). Is it another $100+ vintage NOS?

[Toka]

FWIW, these three are the exact same tube just with different brand names on them (New Sensor owns all three brand names, and the tube comes from the same factory)

Have you tried a Telefunken smooth or ribbed plate? or a NOS GE Owensboro?

-Aaron

Do those Tung-Sols and new Mullards have the same spiral filament as the Sovtek LPS? Or are they the same as the standard production Sovtek?

[indy mike]

I'm not familiar with the Owensboro (KY?). Is it another $100+ vintage NOS?

I believe Owensboro was the last plant GE had producing tubes into the 1980's.

[MMM]

Not to derail the tube discussion much, but does anyone know the capacitance (pf) of the Bellari? I can't seem to find a published spec on it...

[TimB]

The Sovtek lps, the Tungsol and the Mullard are indeed from the New Sensor Reflector plant, but all 3 are of different design/construction. So while they all have a similar heritage, they are not the same tubes between any of the 3. The Telefunken smooth plate is very similar to the Ei 12AX7, as a matter of fact, the Ei used the same tooling and formula and even made Telefunken tubes for the Telefunken company.
The tube I like the best in the VP129 is a older Tung-Sol tube that I have. I also like the Ei 12ax7 almost as much. The Telefunken NOS that I have is very close in sound to the Ei. I have also tried JJ, Sovtek LPS and SOvtek WB, Sino WC rev 9, RCA and a few others as well.


TIm

[gloomrider]

The tube I like the best in the VP129 is a older Tung-Sol tube that I have.

Made in USA by any chance? :)

Thanks for your original post on this. It was a fun ride!

[James Glennon]

I have been using Mullards for years.

Mullard 12AX7/M8137 (military version).


JG

[TimB]

Made in USA by any chance? :)

Thanks for your original post on this. It was a fun ride!

I have yet to try the new New Sensor Tung-SOl and Mullard tubes, but I will be soon.


TIm

[gloomrider]

I have yet to try the new New Sensor Tung-SOl and Mullard tubes, but I will be soon.


TIm

I found the Mullard to be too bright and the Tung-Sol to be even more brittle. They didn't hold a candle to the USA NOS tubes, at least in this context.

[Levitated]

Glad I found this thread, I was about to start a new one about this.

Quick newbie question, would it be possible to try a 12AU7 tube in the Bellari? I really don't know much about tubes, but a friend suggested trying a 12AU7. Is there a characteristic difference between the two (12AX7 vs 12AU7)? Just curious.....

[vinylkid58]

Quick newbie question, would it be possible to try a 12AU7 tube in the Bellari? I really don't know much about tubes, but a friend suggested trying a 12AU7. Is there a characteristic difference between the two (12AX7 vs 12AU7)? Just curious.....

There is a huge difference in gain (amplification factor) between the 12AX7/12AU7. The 12AX7 has approx. 5 times the gain of a 12AU7, therefore your choices are limited to high gain tubes from the 12AX7 family.

You could try JAN GE 5751, these are very close to 12AX7, with slightly less gain but very good specs and they sound great. I replaced the stock 12AX7's in my integrated amp with the JAN GE's and noticed an immediate improvement in sound quality.

Jeff

[Steve G]

There is a huge difference in gain (amplification factor) between the 12AX7/12AU7. The 12AX7 has approx. 5 times the gain of a 12AU7, therefore your choices are limited to high gain tubes from the 12AX7 family.

You could try JAN GE 5751, these are very close to 12AX7, with slightly less gain but very good specs and they sound great. I replaced the stock 12AX7's in my integrated amp with the JAN GE's and noticed an immediate improvement in sound quality.

Jeff

you have to be careful with those 5751s though - they are similar but not identical and it is specific to the preamp. Make sure it's cool in the Bellari before you stick it in there. Trust me - I had a 5751 near disaster one time!

[Levitated]

Thanks for the replies. I've actually been doing a little reading over at thetubestore.com, and realized that maybe the 12AU7s are not the way to go, for the same reason you mention, Vinylkid58. Also, I was just looking at the JAN 5751, as well as the Ei 12AX7. Might try them both for fun.....

Steve, how would I find out if the 5751 is cool to use w/ the Bellari? Contact the manufacturer probably right? Don't think I want any disasters in my livingroom.......

Why do I have the feeling this is the start of a long, costly hobby/obsession? Today a simple Bellari phono amp, tomorrow maybe a tube buffer for the CD player, and before you know it I'm trying out tubes in mono blocks......

[Jim Ricketts]

For a good explanation for sonic differences of various NOS ECC83 tubes, try

https://www.tubeworld.com/vactubes.htm

Drop down the "Preamp" menu and select 12AX7. Good description at top-right.

[Levitated]

Nice, thanks!

[vinylkid58]

Why do I have the feeling this is the start of a long, costly hobby/obsession? Today a simple Bellari phono amp, tomorrow maybe a tube buffer for the CD player, and before you know it I'm trying out tubes in mono blocks......

Costly, not necessarily. Hobby/obsession, you got it.:righton:
If you are like me, you'll be building your own gear in no time. That way, you get to learn as you build and save big money. You can build stuff for a few hundred dollars that will stomp the expensive gear you see in hifi shops.

For more reading material, check out these pages:
http://www.tubedata.org/
Click on the US flag to look for data sheets, I find this is the best way.

http://www.pmillett.com/technical_books_online.htm
Lots of books in PDF format to download here. His main page is good also.

And this is just the tip of the proverbial iceberg.:laugh:

Jeff

[brupri]

FWIW, these three are the exact same tube just with different brand names on them (New Sensor owns all three brand names, and the tube comes from the same factory)

Have you tried a Telefunken smooth or ribbed plate? or a NOS GE Owensboro?

-Aaron

Hi Aaron, I have some of these, how do I know smooth or ribbed, what are the characteristics of either?

[gloomrider]

There is a huge difference in gain (amplification factor) between the 12AX7/12AU7. The 12AX7 has approx. 5 times the gain of a 12AU7, therefore your choices are limited to high gain tubes from the 12AX7 family.

You could try JAN GE 5751, these are very close to 12AX7, with slightly less gain but very good specs and they sound great. I replaced the stock 12AX7's in my integrated amp with the JAN GE's and noticed an immediate improvement in sound quality.

Jeff

Forget about the 5751 in the Bellari. Because the Mu is different, it radically affects the RIAA curve. Boosted bass and rolled off treble. I've been there. Trust me.

[Steve Hoffman]

Hi Aaron, I have some of these, how do I know smooth or ribbed, what are the characteristics of either?

Those look smooth or fake. Look on the bottom. Do you see a Diamond? That's a real Tele.

Ribbed or smooth plate, they both sound the same to me; I could never hear a difference; both magnificent.

[brupri]

They're smooth then, they came out of a vintage Tandberg reel to reel.
thanks, Steve.

[vinylkid58]

Forget about the 5751 in the Bellari. Because the Mu is different, it radically affects the RIAA curve. Boosted bass and rolled off treble. I've been there. Trust me.

I trust you, but the Bellari literature states the tube is in the output section, so how is it going to affect the RIAA curve?

Jeff

[scottabs]

I found the Mullard to be too bright and the Tung-Sol to be even more brittle. They didn't hold a candle to the USA NOS tubes, at least in this context.

I wish I had read the entire thread before placing an order. I read your first post, and immediately placed an order for 2 Tung-Sol's from thetubestore.com, only to read later that the one you liked best was an old NOS US Tung-Sol.