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.
First, I note the following statement in the manual for the PV11:
It is well known that tubes of a given type vary sonically depending on the manufacturer. We have chosen the brands of tubes we supply based on extensive auditioning of available brands. The choice of brands has been made solely on the basis of sonic performance without regard for either cost or prestige. We know of no vacuum tubes available which will improve the sonic performance of your PV11....
... Please note: The indiscriminate substitution of type 12AX7 tubes for the 5751 will seriously degrade the sonic performance of the unit.
Also, apparently four of the six tubes in the PV11 are used in its phono stage, and only two in its line stage. And I would not necessarily assume that a given tube is likely to exhibit similar behavior in the two kinds of applications.
Given all of that, it may be worthwhile contacting CJ and asking if they can tell you what tubes were originally used in the PV11.
Beyond that, FWIW like some of the others I have had fine results with Gold Lion reissue 12AX7 and 12AU7 tubes, in my case in line-level and driver stage applications in a Chinese-made Paxthon integrated amplifier I used for a while some years ago. They handily outperformed a number of vintage tubes I also tried in that amp, including some vintage Telefunkens which go for considerably higher prices.
@elizabeth I hear what you are saying, and for some manufacturers this is fine, from Schiit (or is it iFi?) that have the sockets. But i think they might limit the quality the OP is after.
I’m not a purist, but I dont use the sockets that allow other tube types, b/c it is just another thing in the way of the audio chain. And the OP is looking for good tubes with good bang for buck. IOWs, I personally would not put a socket on a $75 NOS tube.
TBH, im not familiar with your CJ PV11, so i did a quick look up- this is from the 90s? and uses 3 different tube types? of course it is fine to have an older model, but that will tell us more about its general circuitry under the hood. Some amps can handle substitutions, some cant. Some pre amps now (LTA MicroZotl) have a choice of 6SN7 or 12AuX, b/c the circuit board and electronics inside support these different electrical platforms.
@rvpiano: i would like to make some recs on tubes, but it would help me/us to know: 1. Do you have a budget per tube or to replace all 6 right now? or replace just some? Whatever you do, swap out all the tubes of the SAME type. eg, dont replace one 12AU7, replace all of them at the same time. you probably guessed this, but some people dont. 2. I know the Nuforce class D amps you have, but what speakers do you have? 3. What particular aspects of sound quality do you want to change? more or less hi frequency? more or less mids? more ore less bass? more balance overall? a "sweeter" sound? a dryer sound? a colder sound? a bigger soundstage? a smaller stage? a more aggressive or laid back sound? you get the picture....
Rvpiano, You’re using pretty decent tubes but as others have pointed out you can definitely move to a higher level for improved sound quality. You’ve been given some reputable tube vendor commendations. I can vouch for Vintage tube services. Much knowledge and very good selections from Andy. You can certainly exploit the CJ PV 11 true potential with better quality tubes. Charles
Oh, do try some other tubes than the EH and Sovteks! They are "adequate", IME, but certainly nothing special. I have had great success trying 5751's in place of 12AX7's at the driver station for an EAR 890, and there are great options for voicing the amp in a direction you desire, all of which are definitely superior to your current tubes for musical finesse. I like RCA 5751 Triple Mica Black Plates when I want a richer presentation, a "warmer" influence, as it were. If you want a more articulate (but potentially leaner) presentation, try a GE 5751 Triple Mica Black Plate. Now, when you want the best all around performer, IME, try a Sylvania 5751 Triple Mica Black Plate. That is where I settled, but each amp, system, person is different....
Also, Joe's Tube Lore is definitely worth a read through over at AudioAsylum (in their FAQ's section for tubes).
To your question to Wolf, no you can sub in 6sn7s for 12au7s or 12ax7s
Here's the link to Brent Jessee' website (sells mostly NOS tubes) if you scroll down a bit to the yellow section where you see different tube types listed click on 12ax7 and it will bring up not only his list of available tubes but impressions on various respective brands; you can do likewise for 12au7, etc. (Note: I am not Brent nor affiliated with his company other than as a customer) - Might be helpful. Also , if you call him , say Andy at Vintage Tube Services and tell them what type sound you are looking for they can steer you accordingly.
rvpiano, I want to congratulate you on taking the next step to audionirvana. You are in for some silly happy surprises, big grins, and perhaps even some giggling like a little girl-- like the rest of us -- when we find the right tube for the job!
I’ve used tubes for 10 years or so now in various uses in my audio chain. and like you, questioned the tubes abilities, and the higher costs of "better" tubes.
If you just wanted to jump into tubes and get something going soon, I would suggest just calling perhaps 3-4 tube sellers to ask them what they would suggest based on your particular unit (but make sure to call Upscale Audio- they are knowledgable, will help guide you, will ask you what you are powering, etc. In fact, when you buy tubes from Upscale on their website, you are required to type in the type of tube unit that you would be using the tubes for-- in order to make sure they match electronically.
Sovteks and EH are .... okay. But the next level up you will hear differences in sound... say to the Gold Lions, as they said above. But the next level would be like modern made tubes that are well-designed and manufactured with good Quality Control (like PSVane, modern Mullards, etc), then like the NOS tubes that dont cost an arm and a leg, at the entry level rung, and on upward. I always try to buy the entry-mid level NOS that have really "low microphonics" means that the tube should have been tested on a tube-testing machine to check its current condition. eg, Upscale does this, like tube depot, etc will write down the "matched" electrical voltages/etc of each tube. so you know you got a "matched pair", eg, when I bought 2 tubes for a preAmp, and when I bought 8 KT88s. But what type of tubes are you looking to upgrade right now?
EH and Sovteks can be amazing sounding tubes so those are well chosen...Gold Lion 12AX7s (new ones) are great and not too pricey…NOS Mullard 6201s are also very nice, and yeah…you can tell the difference. I now use 6SN7GTBs in both my SE power amp and preamp (that has 4 of them) and have been having fun rolling around that tube…NOS USA Amperex, Sylvanias, blah blah…and they all make different tonal flavors.
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