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Questions from a Tube Preamp newbie

I have my Rogue RP-5 back from warranty repair and I am loving how it sounds. While at Rogue, they installed 4new JJ 12au7-s tubes. Sounds great. I have some questions.

1. with about 2 hours daily playing, how long do typical preamp tubes last (I have heard Rogue's, like CJ, can be hard on tubes)

2. Do new tubes need broken in? if so, what is normal time frame?

3. Does tube rolling really make a difference on a preamp vs power amp?

4. What is the general concensus on JJ tubes for a preamp? Again, I am really happy with the sound, so I probably won't change. However, I will eventually probably get the itch.

Thanks
aberyclark
nordicnorm
313 posts
 
JJ tubes are a fine budget tube (~$15/tube).

I once had a preamp that used 12AU7 tubes that came with JJ’s. I found the sound to be pretty uninspiring so I changed them to Psvane 12AU7-TII.

At US$50 each, they were a significant step up sonically from the JJ’s.

Here's a review of them on AudioAsylum.
aberyclark OP
1,410 posts
 
What are the sound signatures of the Gold Lions vs the stock JJ's? The NOS Mullards are pricey plus, I hear they do not last as long
stereo5's avatar
stereo5
6,571 posts
 

I received my RP-5 on October 1, 2016. The Mullards have been in the preamp since the second week of October 2016. They still sound great with no increase in noise.

aberyclark............

What was the problem with your Rogue preamp?  If I remember correctly there was a lot of hiss, etc.  What did Rogue do to it besides change tubes?

mofimadness's avatar
mofimadness
5,783 posts
 
1. Most preamp tubes will last 3000-5000 hours. Some are speced out to 10,000 hours, so there are exceptions.

2. 40-50 hours, there are exceptions.

3. Depends on how the circuit is designed and how the tube(s) are implemented within that circuit. Tube rolling can make a huge difference or none at all.

4. Never been a fan of the JJ tubes.

I have quite a few of the Mullards and have never experienced a premature failure or an increase in noise?  Excellent tube.  The Pvsane tubes are also very, very good.
hifiman5's avatar
hifiman5
1,836 posts
 
@stereo5   My previous post should have been stated more accurately.  The NOS Mullards I used were 4003s not 12AU7.  They were recommended by Upscale for my line stage.  Glad to hear you're having good luck with your NOS Mullards.  The 4003s I used yielded an amazingly smooth texture to the music.
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