Question for tube aficionados

Very interesting posts!
Also a myriad of suggestions.

I agree the phono stage of the PV11 is awesome.  Records sound way better than CDs.
Thank you lowtubes for your expertise.
 I will look for the Amperex 7316.

Just another note, if anyone knows more about 12au7, 12ax7,5751 tubes, it’s me. I’ve been rolling tubes for years and I have a huge stock of all the top vintage brands. I can’t believe how people comment on subjects they know nothing about. No wonder people get so confused when they need direction. I tried a lot of tubes in the PV-11 line stage and the 7316 will be the tube that will give you most satisfaction. It’s because it is very revealing but smooth and musical too. If you desire a more analytical sound, RCA clear top.   Mullard Old Logo 1960’s 12au7’s are my 2nd favorite along with the French made Cifte 12au7’s.  I personally felt the phonostage of the PV-11 was way superior to its linestage and I actually found putting in all quality tubes in the phonostage didn’t improve its sound. So for the  phonostage, I used a vintage 5751 black plate triple mica (doesn’t matter their all great), basic current production Russian 12AX7’s and a Mullard 12AU7 or 7316 Amperex for the 12AU7. Good luck.  

Raindance 3-16-2018
They are also prone to oscillation with the wrong tube choices because of CJ's refusal to follow good design practice and use grid stopper resistors.

Interesting point, which I hadn't been aware of.  I couldn't find a schematic for the PV11, but I took a look at schematics for the PV10 and PV12 which are available at HiFiEngine.com.  And I can confirm Raindance's assertion for at least most of the tube stages in these designs.  I have no idea why CJ wouldn't have put grid stopper resistors having at least relatively low resistances into these designs, but as Raindance indicated not including them is definitely not good design practice.

The following article provides good background on this subject, even though it is oriented toward guitar amp applications:

http://www.aikenamps.com/index.php/grid-resistors-why-are-they-used

Regards,
-- Al
 

I'd agree that not all NOS tubes are genuinely "new" old stock and a reputable dealer is worth seeking out.  
Not every NOS tube is by default always better than current production,  it depends on numerous variables.  I can vouch for the upper level of the Psvane tubes for example. 

Based on my experience I believe that you can find high quality NOS tubes if using a honest dealer/vender.
Charles 

Hello, I’ve owned the PV-11 for over 20yrs now. It was my main preamp for 10yrs but I have moved onto a AR SP-11 Mk 2. I still have the PV-11 in my collection of preamps. The tubes that sounded the best to me in the PV-11’s linestage is the Amperex 7316. I think other Bugle Boy 12AU7’s may sound good also but the 7316’s were the most musical and revealing tube for me. Keep in mine that the linestage of the PV-11 is fine but it’s phonostage is totally awesome. 

"The difference NOS tubes will make is like cables - not much."

Interesting analogy except with cables you can show them off, not so much with many tube designs, particularly preamps. Just like anything else in audio, the depth of one's pocket is the only limiting factor.

The difference in sound between NOS and new production tubes is slight and you will spend a lot of money finding NOS tubes that are (1) not fake, (2) not microphonic (3) not noisy. My 2c worth. I gave up the chase years ago and now use matched and tested JJ or Sovtek tubes.

Also, CJ amps of this vintage typically use circuit designs that are not optimal to produce a "tubey" sound. They are also prone to oscillation with the wrong tube choices because of CJ's refusal to follow good design practice and use grid stopper resistors. The difference NOS tubes will make is like cables - not much. I'd stick with what works.

I recently upgrade my Cary 120 with new Gold Lion KT-88's and Psvane 6sn7.
Previously I had Gold Lions, but they had quite a few hours on them. I also had Tunsol 6sn7's
The Psvane Grey bottle are a matched Quad and the Gold Lions are a matched octet.
I'm constantly blown away by the increase in soundstage and detail, both high and low.
Psvane makes both a 12au7 and 12ax7.

I will be upgrading my Cary SL98P F1 from the Tunsol 6sn7 to a Psvane grey bottle matched quad.
I like the Psvance, that much.

One word “ TELEFUNKEN “! I have NOS 12AU7’s ( E82CC, ECC82) in Telefunken , Tesla, Seimens , Mullard , RCA, Tungsram . They all are better than new stuff . They have distinct tonal differences . I use 5 different NOS rectifier tubes which raise or lower the voltage and effect my power tubes . So driver and rectifier tubes are all NOS. They last a long time . Power tubes - I have NOS GEC KT88 and KT66 , NOS Tungsol 6550 ( 3 hole ) , and SED Winged C 6550 and 6L6GC. They are better than current production tubes and more expensive. New production, I have Gold Lion KT88 and KT77 ( very nice sound ), Psvane TI KT88, Tungsol KT120, JJ KT77. Of the new stuff I am fond of the GL tubes . But for your application Telefunken NOS. FYI Brent Jesse’s site gives a very accurate description of SOUND from various tubes . FWIW, I have $3k in tubes for a $1500. Amp , so you see where this can take you 😝. Shoot me a message if you have specific questions . Happy Listening , Mike B. 

I asked CJ what the tubes were, and surprisingly the reply was  the 12AX7 Mullards are NOS, the others are new production.
The question then becomes, which Mullards are included?

I have a VTL 2.5 preamp
I ran OEM 12AU7 JJ’s up until about 4 years ago.
I went to NOS 12AU7 Amperex Bugle boys - a significant improvement over the JJ’s
I just got NOS Telefunken 12AU7’s - another significant improvement over the Bugle Boys. There’s a new level of openness

+1 lowrider57. I’m not suggesting that the CJ recommended tube option is a bad one. For that cost I’d would pursue the NOS tube pathway. I like the idea of trying the RCA tubes as earlier considered above. I’d have CJ clarify if their tubes are NOS or current production. Again their choices may be very good sounding. Truth is there are many good tube rolling options for the 12AX7 and 12AU7 family.

Charles

@newbee , you may be right. I traced the PV11 preamp back to at least 1992, so the Ei and Mullard could have been NOS. But CJ is now re-tubing the unit, and $310 is a very low price to include 2 NOS Mullards.

I think lowrider57 may be incorrect. The Mullards could be new production or old. The Yugoslavia 12AU 7's are definitely old stock. They haven't been inproduction for 20+ years. When this unit was first produced I don't think  new production Mullards were available - my guess is that they are more probably old stock and I think that the NOS and new production do not have the same tonal qualities. 

I'm not familar with your pre-amp but I suspect that the V1 and V2 positions are likely the positions most affected by tube changes. If that is so, and if I wanted to play with tubes changes, I would start there keeping in mind that different brands have different tonal qualities and it helps a lot in selecting tubes you want to try to have some 'tonal' goal and try tubes that have a similar tonal signature.

It sounds like these are new production tubes. To go in this direction would get u right back where you started.
The only upgrade path is to try NOS. 

The Conrad-Johnson description of the tubes is as follows:
 “V1 & V2: 12AX7 MULLARD| V3: 5751ELECTRO HARMONIX | V4, V5 & V6: 12AU7 YUGOSLAVIA.”

No further description than that.

I contacted Conrad-Johnson.  They sell a complete set of recommended tubes for the PV 11 for $310.
I wonder if I should go in this direction.

I never had good luck with that variant. They often sounded harsh and microphonic. So I'm not the best person to ask...

atmosphere,

 What make 5814 would you suggest?  or What to avoid?

Thanks for the info.  If the RCA’s don’t work out, I’ll return them and try 5814’s

The 5814s and 7316s are better grade 12AU7s.

I go back and forth with the fantastic Amperex 7316s, and the equally fun CBS 5814As. These are my faves.

What I can add is the best 12AU7 are 7316.

And the best of these are the Amperex Bugle Boys...

A lot of 5814s around- be careful- many are not as good as even the Chinese 12AU7s (which are really fairly competent).

Schubert,

Are you saying that 5814 can be used as a substitute for 12AU7?

For Classical music I use 5814 and 5751 for 12Ax7 subs .
IMO opinion RCA cleartops are too bright on strings , maybe OK
in warm pre  but 5814 are always more musical to my hears .

Rvpiano,
I’m looking forward to your listening impressions of the RCA tubes in the CJ preamplifier. Curious to know how much of a difference you hear compared to your current tubes. I believe this is a good move.in terms of venturing into the realm of recommended NOS tube rolling. The cost of the RCA tubes seem very reasonable.  Good luck.
Charles

I would imagine RCA Cleartops would work well in a CJ due to their airy high-end.

I like the 5814a variant of the RCA Blackplate. It is more dynamic than the 12au7. The Cleartops are good if you like extended highs.

Re... the Blackplate 12AU7, the older the better. Early 1950s, low noise is best for the classic tube sound.

I ended up ordering a matched pair of 12AU7 RCA Cleartop (side getter) tubes from Brent Jessee, raved about by both Brent Jessee and Joe’s Tube Lore, for $69/pair.
Tube Depot is way overpriced.  I’ll have to use my credit on something else.

lowrider57,

Never mind, There’s only one 12AU7 Blackplate there!
My mistake.
 Sorry for the post

lowrider57,

There are many RCA Blackplates at various prices on Tube Depot.
 Do you have a preference?

@rvpiano, the RCA BLACKPLATES are very good tubes for a decent price. Known for their dynamic open sonics and classic tube sound. Make sure the pair are matched and tested for noise.

The Joe's Tube Lore posting is from 1999 from the looks of it, but I didn't read down through the pages. You'd be hard pressed to find much for $5 these days!

The 12**7 tubes last quite a long time, so it's well worth it to step up to something really nice. The Brent Jesse descriptions of the sound qualities of various tubes is very helpful and accurate. As long as the 5751 and the 12AX7's in your PV11 are quiet, I'd go for the gusto on the 12AU7's for line stage... unless, of course, your budget allows for doing them all right now.

lowrider57,

Based on the recommendation at Joes Tube Lore, I’m getting a pair of RCA 12 AU7 in place of the Gold Lions.  According to Joe, they should cost around $5.00. Tube Depot has them for 12x that  price, but it will cost me about the same as the credit I’m getting.

I agree with previous comments to first replace the 12AU7’s. But, substituting Gold Lion 12AU7’s will be a horizontal move; there will not be a dramatic improvement. To really open up your preamp you need to go with NOS tubes. There is so much good info on the sonic signature of NOS tubes at Joe’s Tube Lore... https://www.audioasylum.com/scripts/d.pl?audio/faq/joes-tubes.html
and Brent Jessee’s site...
http://www.audiotubes.com/12ax7.htm

And almarg has stated an important point about the use of the 5751 variant in your CJ preamp...
Please note: The indiscriminate substitution of type 12AX7 tubes for the 5751 will seriously degrade the sonic performance of the unit.

The 5751 has lower gain, so it's recommended to stay with a 12AX7.

Yes try NOS OS 5751s they were all the rage 10 years ago.  They are more reasonable these days.  I advise you get Sylvania blackplates, RCA easier to get and even GE again blackplate and their 5 star brand.  If your up to a search the Raytheon windmill getter 5751 is very good,  Get triple mica preferred over doubles.  Sylvania's Gold Brand and RCA Command series are worth looking for. Good Luck tube rolling is a slippery slope.it can be addictive, PM me for more advice/help.

You can try swapping tubes for sure but even better is to change a few of the resistors.  Carbon film, metal, shinkoh, caddock, etc.  cheaper way to go and a lot more fun!

Happy Listening.

Nos vintage tubes sound significantly better than any tube made today and they last much longer. I use Mullards, telefunken and rca 12—7’s. The rca clear tops are nice and about 12$ a tube. I don’t like nor have had good luck with modern day reissues. 

Have tried a fair sample of the triple mica 5751 black plate tubes, as well as nos mullard 12ax7's.  Have not tried the gold lion 12ax7s, but can relate that the grant fidelity psvane 12ax7 are one fine tube.

Pretty simple, really.  Better tubes equal better sound.

For these variants, with few exceptions, you need to look toward old production.  Not necessarily NOS, though so many aspire to that.  I found you can do VERY well for yourself buying tubes others sneer at as they come up measuring as having obviously miles on their clocks.  Old tubes often play quite a long time, and pretty much sound great until they give out.

As has been mentioned the best 12AX7 tubes are 5751.  What I can add is the best 12AU7 are 7316.  Both tubes will cost you deep in the purse.  Both tubes instantly convince you that you won't go back.

If you do want to buy new production tubes, Shuguang triple mica 12AX7B aka Silver Dragon and Psvane 12AX7 and 12AU7 stack up surprisingly well

I mentioned the 6SN7GTBs as between my preamp (Schiit Freya) and my amp (Dennis Had Firebottle HO) that's all there is for non power or rectifier tubes. My previous amp used 12AX7s and 12AT7s with my preference winding up as new Gold Lions for the 12AX7s and NOS Mullards for the 12AT7s.

 I will soon have a credit of about $130 from Tube Depot, having already bought but not opened, a complete set of tubes for my preamp.
With this, I’m thinking of getting two Gold Lion 12AU 7’s for my line section.
This won’t cost me anything extra. If this doesn’t make much difference I’ll go to more expensive NOS tubes (of which Tube Depot has a limited supply.)

@hedgehog gives good advice above about how and when to replace tubes: line stage first, then phono section, and make mental notes of the sound changes as you progress.

1. Line stage: 2 x 12AU7: I’m assuming
2. Phono: 1 x 5751 and 3 x 12AX7
https://conradjohnson.com/owners-manuals/pv11man.pdf

12AU7s: Lots of good opportunities here.
The NOS Mullards are end stage tubes for many, meaning once you hear it, you never let go of the tubes. I bought 4 matched of these tubes for about $125 each after shipping, taxes, matching, etc. from Upscale last year to try in my PrimaLuna tube integrated. I also needed a softer top end b/c I have ribbon tweeters in my speakers, which can burn your ears with more aggressive tube profiles.

The Mullards (specifically the M8136 model from Upscale) are expensive, yes, but everything they said was true: softened but very beautiful top end slightly rolled off. The soundstage is to do for, it puts the band in the room with you. Not many cons to this tube other than a slightly rolled off bottom end. RV, I think this would be an obvious choice for you.

The NOS Brimars are excellent too at $80 each, I have a pair, BUT it does not offer the softened top end you are looking for.

The RADIOTECHNIQUE 12AU7s: for $95 each, have not tried, but probably excellent+.

there are other NOS tubes out there. I recommend going to Upscale website, and watching the videos on each tube that they sell.

Having tube rolled integrated amps, phono stages, and amplifiers, I can say that tubes can make all the difference in terms of gain, clarity and other aspects. The tubes in your CJ pre will make the most difference. I replaced the stock 12ax7 tubes in my pre with GE 5751 tubes and it made an incredible difference in terms of clarity, gain, presence, and soundstage. Those tubes were $60 each, but it was an immeasurable investment.

But I also did my research in terms of what tubes were the most complementary to my unit beforehand.

 

I've had three different CJ tube preamps over the years.  I found that European as well as some Japanese NOS tubes made a significant difference/improvement.  Be careful to get low noise tubes, particularly in the phono section.

I have always gotten solid advice and feedback from Brent Jesse, Andy at Vintage Tube Services, and Upscale Audio. I’ve purchased from all three over the past 20 years, and have not gotten a bad tube from any of the three. 

I would start by replacing the two 12AU7s in the line stage with a very high quality matched pair, as all sources will run through that preamp stage. Replace each additional tube type in phono section in stages to evaluate what each is doing to your sound for your future reference. You may notice some tube positions make larger differences than others.  Have fun!

Cheap present day 12a*7 types will never equal the sound quality and lifespan of vintage types!

Vintage pre-1970 GE, RCA, Sylvania, Mullard and Telefunken are still the best made and sounding of the 12a*7 types! Far better (and longer lasting) than present day production! That is why they command high prices!

Thanks to everyone for their suggestions.

My speakers are modified Dalquist DQ 20’s.

Overall, the system is fairly well balanced.  What could be improved is occasional brightness in the treble, especially in the line stage.

 Ideally, I’d like to replace all six tubes, depending on the cost.

Amperex Nos or decent testing units 12AX7 
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