Question for tube aficionados

I have a vintage Conrad-Johnson PV 11 preamp.
 I’ve always re-tubed it  with the cheapest tubes from Tube Depot (e.g. Electro-Harmonix 12AU7 and 12AX7, Sovtek 5751 and the like.). I’ve been very happy with the sound.
 My question is:
 Would it be worthwhile to spend more money on more exotic tubes?
  Would there be any appreciable difference in the sound?
 I’m powering the system with NuForce Reference 9 V3 monoblocks.
I have Shughang Black Treasure 12AX7LS and they are mostly better than Telefunkens. Tighter, cleaner bass, clean bright sound without glare and sweet highs. Slightly reduced air.
I have a used the PsVane with much sucess.
I have an Amp that uses the 12AX7 In that I have put Sovteks (Basically nothing more than a tube to put in a tube socket) 
Also put in Vintage Mullards and Tele's . The matched Set Psvane to me sounded better balanced, clearer and detailed.
The Mullards a little bright & the Tele's A little to creamy for my system.
 But it is always specific to equipment.
I also had a tube phono section which required both pairs. Again I tube rolled the Sovteks and
only replaced with the PsVanes. Vintage is great but they have their issues.  With the PsVanes were very quite and for the price worked great and you should have no regrets. At worst they become a very good back up set just in case your vintage choice go south. But now my vintage 12AX&'s are my back up and the Psvane are still in and working fine for well over 2 years.
Lastly give them a little time to break in. Out of the box you will know you are the right path.

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.

This comment is backward. The book is saying not NOT to replace the 5751 with 12ax7. The higher gain of the 12ax7 would overdrive the circuit, being 30% higher. That’s why it says not to indiscriminately do that.  
If the CJ uses any 12AU7's try NOS RCA 5963. These are always a serious upgrade from your new stock 12au7's and they're a plug and play replacement. Highly recommended.
I owned the PV5, PV8, PV11 and PV12 over the years. Going from memory, seems the later versions starved the tubes a bit. before you start serious tube rolling, may want to measure the plate and cathode voltages and see what there are, then calculate the current going through the tube. On my PV12, there was less than a milliamp, so changed out the plate and cathode resistors to at least get the current up to a milliamp. sounded much more open and less constrained.

The PV5 I wish I had never sold...did not have the highest resolution, but was such a musical sounding piece.

The current production Gold Lions produce a sound that comes closer to the old production Philips tubes such as Mullard and even the less rich sounding Amperex.  Still many of the old 5751s while excellent in regard to tone are even better for imaging and sound spectrum profile balance  i.e. relative amounts treble to mid to bass that is partly a function of what a tube type can alter sort of a tone matter but different in my mind.  Gold lion does not make a 5751 to my knowledge but I sure would like to see them try. They do make a 12AU7.
There has been a run on whether a 6SN7 can be subbed for a dual triode 9 pin minature, and it can in some applications take the place of a 12AU7 in some applications. adapters can be bought on Ebay and elsewhere.  I am not sure whether you pre would allow the diferences betwen the 2 or not, but my understanding is that they serve similar purposes.  6SN7s are said to be very linearand there are plenty of 12AU7 bashers around on tube froums.
I am actually delighted with my system right now. My search is over.
 The Telefunkens are my tubes of choice.
So that's the problem with tube rolling, they sound different and depending on your tastes and your system they may or may not work for you. I found the Telefunkens to be pretty good, I liked them more than some Amprex tubes, including Bugle boys. As you wrote, they are great tubes, but just not in your setup. If you are already used to and like the sound of the EH, I think you might want something that hits with a little more punch than the tele or amprex tubes, I would try the new Golden Lions or the psvane, if you want to try NOS I would recommend you look at some RCA blackplates from the 50's or early 60's. I've tube rolled a lot of different tubes, and it's always a give and take with tubes. Amprex gets such a good rep because they are very balanced, but that might not be what you are looking for, and you don't really understand that until you try them out for yourself. Happy hunting
So you like the Tele's, they're excellent tubes. You gave the Amperex a chance, as long as you burned them in for 60 hours and then did some critical listening.
Well, I’ve done a lot of listening lately, and on my system, the Telefunken tubes work better than the Amperex. They are just cleaner and more elegant.
 I’m sure the Amperex are great tubes, but they don’t work as well with my setup.
 It’s possible if I gave them more break-in time they would sound better.  But I don’t want to suffer through that period when I can enjoy my system right now
I have some experience with the 12AX7 from Psvane. I would definitely give them the nod over all current production tubes that I've tried, except the Gold Lion. The GL gets the nod for tighter, more tuneful bass.

I would not put either brand ahead of a quality, tested, NOS Mullard, Amperex Bugle Boy, Siemens, or Telefunken in sound quality. As with all things audio related, this is a subjective statement. There are other NOS than can be quite good, of course, but those are the biggies. They all have a sometimes subtle, but definite and unique sound character. The different brands will excel in different equipment and systems, and based on listener preference, of course.

I'm not surprised that you are digging the Amperex tubes, as that is one heck of a 12AX7... plenty of detail and the tube black magic, and a nice match with a neutral-to-cool sounding amp. If still running the Belles, I would expect many to lean toward the Siemens or Telefunken. All just generalizations and personal preferences on my part, of course. 

If you can afford to keep both, do it. You may decide to make a power amp change down the road, and those NOS Telefunken tubes could come in handy... they're not going to go down in cost in the future. I could kick myself when I think of the NOS tubes I've sold along with gear over the years.
Telefunkens and Amperex are no better than new tubes like the psvanes... has anyone compared all three side by side?

I haven't tried the Psvane, but according to forum members it is a premium quality new production tube at a premium price. 
A 6SN7 costs as much as a high quality NOS tube.

Looking forward to the answers to your question.

Right now, I’m very happy with my NuForce Reference 9 V3’s.
And they’re a few thousand less than the Bel Canto.
 I know there is extreme predjudice against class D.
But you have to hear the NuForce to render an informed opinion
Post removed 
It seems that the Telefunkens and Amperex are different enough so as to require an either/or choice. Some have said that the Telefunkens and Amperex are no better than new tubes like the psvanes... has anyone compared all three side by side?
At the risk of being a homey .The BelCanto 600M's are only class D I would consider .
durk. Most Bugle Boys sold are fake .

@schubert Very interesting, makes a lot of sense, and explains the situation.

@rvpiano Have you ever thought about stepping up to the Bel Canto Ref600M's?  From everything I've read, they could be your dream amps.

RV, I was really lost about the Belles ,my 150a Reference VII has no problem driving my 4ohm , 87db Totem Sig Ones which are hard  to drive .
Knew nothing about the DQ 20's . Worked internet , 4-5 reviews all noted how hard it is to drive, several said hardest speaker to drive they had ever encountered .
One said 250 watts a side was bare minimum , 400 would be better, guessed its to be a 82db load .
Objective evaluation of improvements in a stereo system is hard to arrive at.  There are so many subjective factors involved.  So I pulled out the Chesky “Ultimate Demonstration” disc that I had listened to prior to tube and amplifier changes. This is a very demanding disc which revealed severe limitations in my old system in just about every area.
Listening to it again now, I found the system to pass most of the tests very well. Of course, you could say there’s at least some degree of subjectivity involved here, too.  But, at least it’s somewhat objective.
Could be.
 The bass response is far better than the original was.
Really quite impressive!

The main thing, though, is that it just sounds better with the NuForce.

Interesting.  The figures in this review suggest an average-ish impedance curve.

Did the modifications make them harder to drive?

Modified Dalquist DQ 20’s.
The Belles just didn’t push them hard enough for impact.
I sold the Belles. They were definitely not compatible and were not powerful enough to drive my system.
The NuForce are much stronger, and they sound fabulous.
Thanks to all of you that gave advice about NOS tubes.
They make a HUGE  difference in the sound of my set.

You’re absolutely right,  As I mentioned, the tests were only preliminary.
I haven’t given the Amperex enough time yet to burn in yet.
Im going to leave them in for a while to give a more thorough evaluation.
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.
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.

@rvpiano, a couple of questions;
Have you given the Amperex enough time to burn-in? Run them for 40 or 50 hours and then evaluate them.
Do you know if these are 1950s issue and what is branded on the label?
   The 7316's should present a 3D image with a sweet midrange. I agree with you that "Telefunken has a more refined and perhaps, clearer sonic picture."
But, as others have stated above, I find the premium, low-noise Amperex more musical. I'm not discounting your findings in any way, but I wonder if they need more run-in time.

If you plan to live over a year or two, wise to keep both .
Their value will not decrease .
Well, I got the Amperex 7316 tubes today.  Excellent tubes.
In preliminary testing, comparing them to the Telefunken 12AU7’s, I found the Amperex to have stronger bass and a bigger and more forward presentation than the Telefunken, but the Telefunken has a more refined and perhaps, clearer sonic picture.
Both are excellent tubes at almost the same exact price. My dilemma is, I can return the Telefunken, the Amperex, I cannot.
I don’t know if it’s practical to keep both.
CJ’s answer to the question of the effect of the line stage tubes on the phono section of the PV11:

“If you are connecting the PV-11 MAIN OUTPUT to your power amp, then the
12AU7 in the line stage would affect the sound quality. If you are only
using the record output then the 12AU7 are not in the audio circuit.”

I’m not surprised that you notice such a significant improvement in the sound quality. The point numerous posters have made on this thread is true, better quality tubes are unquestionably impactful. Congratulations. I didn’t understand the comments of some who suggest that there wouldn’t be much of a difference. Average quality tubes will only restrict/limit the true potential of your preamplifier. The basic design and circuit of the PV 11 is good, but held back by mediocre tubes in the line section. 

It certainly is true that the phono stage of the PV11 is wonderful.
 I’ve placed a bid for a pair of Amperex 7316 tubes on eBay.
Meanwhile, I’m sampling NOS Telefunken AU7 tubes.
Amazingly, these tubes have brought the sound of the line stage very close to the phono stage. If I win the bid for the Amperex, I’ll compare them to the Telefunken.

Hello Rvpiano, I had no intention on visiting this forum again but I’m on a email list that generates recent and past discussions and I browse the list for interesting topics. 
So to answer your latest question, I believe that the unit can play it’s phono section without tubes in the line stage- but I also believe that when tubes are in the line stage, it may affect the sound of the phonostage slightly. 
When I used my PV-11 as my main preamp, I chose to use the purest and most revealing digital / cable front-end but for for my phonostage, it was very different, I chose a very musical cartridge. This was how I balanced both sections of the PV-11 to sound close and very good.  I still do not understand why CJ would make preamps where one stage would sound so superior to the other.  This is not the only preamp they have done like this.  I believe CJ really believed at the time that digital sources were all analytical and hard sounding. As I mentioned before, my main preamp now is the Audio Research SP-11 Mk2 and it has a wonderful phonostage that is definitely on par with its line stage but I actually prefer the sound of the phonostages from CJ tube preamps.  I have my system setup to use the line stage of the AR but my vinyl is played via the phono section of my CJ PV9a.  Rvpiano, if you check eBay, you’ll see 7316 tubes labeled all different names, but you want the ones made by Amperex and it does not matter if the getter is round or D shaped, they sound identical. Good luck enjoying your PV-11 and try balancing your system as I did when I had my PV-11 as the main pre. If you ever think about upgrading, don’t do what I did and sell the PV-11. It took me years before I got mine back.  Keep it because many of Conrad Johnson preamps made in the 1980’s have killer phonostages. My favorites CJ phono sections are the, CJ Premier Three, PV-5, PV-8, PV9a, PV-10a and PV-11.  All of these have their own special tube magic.  
rvpiano, Check with CJ, but FWIW I can't think of a single reason why tube selection in the line stage would affect the performance of the tubes in the phono stage, except for the obvious one is that the phono stage signal passes thru the line stage therefor any tonal changes brought about by the line stage tubes will be reflected in the sound from the phono (or any other) source.
I have a Unison hybrid integrated which uses 2 12au7s in preamp end.  I have used two different Mullard 12au7s, RCA Cleartops, and Radiotechnique, but the Siemens 12au7 NOS (got mine from Upscale) beat them all.  Beautiful full bottom end, great midrange, and an open and fantastic top end, no brightness but crystal clear.  Wonderfully dynamic.
Concerning the CJ PV11 amplifier, does anyone know if the two 12 AU7 tubes that drive the line stage have any effect on the phono stage at all, or do they just affect the line stage alone?
I have no idea what you’re talking about, but I can tell you the preamp is terrific,
even after all these years!
Actually on all 3 of these models we do employ grid resistors on all gain stages , typically a 47R5 resistor. All CJ preamps use grid resistors either 47R5 , 100R or 332R.
Thanks, Coppy. Good to know.

That information doesn’t appear to be consistent with the schematics I looked at for the PV-10 and PV-12 at, and 47R5 (i.e. 47.5 ohms) seems much lower than usual for the value of a grid stopper resistor that would be effective in these kinds of designs. But in addition to the high confidence I would have in an answer provided by Mr. Fischel the bottom line would seem to be, as you said, that "their equipment consistently sounds so good."

Thanks again. Regards,
-- Al

Hi Folks...

Need to correct almarg and raindance about those grid resistors.  I was in touch with Jeff Fischel, now heading up c-j, about those PV-11 grid resistors.  Apparently the sources the previous posters used were wrong. Here is his reply to me:


 Actually on all 3 of these models we do employ grid resistors on all gain stages , typically a 47R5 resistor. All CJ preamps use grid resistors either 47R5 , 100R or 332R.


 Jeff Fischel

conrad-johnson design inc.


Guess doing it correctly is one reason their equipment consistently sounds so good.

As a general note, please remember also that replacing a tube alone is not good enough. Compensating tube production variations, tube aging (and, especially, when using equivalent models) always demands a check and adjustment of bias voltage. I experienced surprisingly significant sound differences from the bias voltage differences of 5%. To make it more challenging, certain systems will benefit from setting a bias voltage that is different than the one recommended by the amp manufacturer. Additionally, my recent observation indicates that the replacing tubes and adjusting bias can also introduce embellishment and extension of trebles that can be easily taken for increased resolution while it only adds graininess.
doing the CJ tube replacement for $310 would be a quick and easy way to get things squared away. Then, down the road, you could roll some tubes. But I'm sure part of that $310 is a fee for their special knowledge of the right tube combination. Maybe not the best value per se, but definitely a quick and easy way to clean the slate and start from a proper baseline. 

But i would have to agree that the Gold Lyons would be more of a lateral move. Absolutely nothing wrong with that, but i just try to make a little bigger move when I do an upgrade.

I'm not talking about exceeding the $130 budget either. But the sound quality gains will be significant, especially since preamps tend to have more influence on the final sound characteristics than amps (and yes, I know, I know, some of you will argue with that ... yeesh).

In fact, you may just ask yourself, "why did it take me so long to figure this out ... :)" 
I used to have both the PV11 and PV12. NOS tubes did sound better, but if memory serves, seem to recall in both preamps the tubes were run in a current starved condition. You may want to measure the current/voltage flow through the tube. I dropped the plate load resistors and got much more open sound, but do not remember the values.

Still wish I had my PV5...that preamp made real music.

I have a near 25 year old Audio Research pre-amp that came new tubed with Chinese 6DJ8.  I liked the sound quite a bit and decided after a few years to experiment with tubes. Holland, Bugle Boys, Amperex and so on came and went.  ..many different manufacture countries and brands  rolled in and rolled out, until I encountered a Siemens & Halske 6922 grey plate from the late 50's - early 60's.  That was the tube of choice for more than decade until I tried a 1959 Valvo Pinched Waist 6922 Cca, which was great for about 2 years of light use when it began to fade musically. Now it's a 1975 silver single wire Reflector 6N23 which is king of the hill.

The point being the right tube(s) can make or break your sound.  Do some tube rolling. What doesn't work for you can probably sell easily on eBay.
I owned a PV11 for many years... a truely wonderful preamp.  I loved it.

What is wrong with calling CJ directly and talking to them? 

CJ knows the tube market really well and can help you make a decision.. they have seen it all.  Getting other opinions is great, but why this apparent aversion to calling the manufacturer?   CJ is a good company with good folks who know what their stuff.

I would start with CJ first, then branch out.

Bruce in Philly