Tube Rolling questions from a recent addict:


I recently entered the wonderful world of vacuum tubes with a Cary SLI-80 integrated amp. WOW what a sound this thing produces! The Cary and its seductive little glowing crystals of joy has made the single most dramatic improvement to the sound of my system since I added my Infinity IRS Delta speakers. Now I understand why tube-heads go on about mysterious NOS finds and seemingly magical differences between certain tubes. I’m both happy, and sad, to say that I’m hooked!

 

Anyway, on to my questions: 

  • When tube rolling, what are some recommended strategies when comparing the sound quality of different tubes?

 

  • Is it OK to power your amp/preamp down, switch tubes, and then power right back on a couple minutes later? I know tubes don’t like to be power cycled like that. But how else can one compare the sound of different tubes?

 

  • Generally, is there a bigger sonic difference between rolling preamp tubes, or power output tubes? (I know, I know, YMMV.)

 

  • And my most technical question. The Cary SLI-80 uses a one 6SN7 tube per channel as a “phase inverter”. From the manual, “the phase inverter is a self-balancing split load configuration utilizing the 6SN7”. Is this “phase inverter” part of the audio signal path? Can I expect to hear differences in rolling different tubes in that spot?

 

Thanks in advance for any other Tube Rolling 101 advice!

 

(P.S. – Thanks to everyone on Audiogon that makes it, IMO, one of the best places anywhere for higher-end audio and music fans everywhere.)

 

Enter your text ...
128x128mhwalker
Yes the phase inverter will make a difference. I would switch out the small signal tubes first then the power tubes. 
the manual for my Aesthetix Romulus states that before changing tubes, the unit should be fully off for 15 minutes, with power cord removed...
Read "Joe's Tube Lore". Think it's posted on the tubeasylum and elsewhere. 

Agree w/analogluvr, change preamp tubes first for biggest impact. Cheers,
Spencer
Another great site to read about tube-ology and another authority on good tube matching to specific electronics. Vintage Tube Services Andy Bowman is still one of the best. 

http://vintagetubeservices.com

Laissez les bons temps rouler!

FWIW, IMHO, the principal benefit in changing tubes, power or small tubes, is to either get a more quiet tube (small tubes), get more power (from some large tube types) or more likely just changing the tone (all tubes).

If you are thinking about changing tone then you must be well acquainted with the tone of your present set up and have identified changes that you want to make in you systems tone before you start rolling tubes. Once you know what changes you want to make you should be able to communicate your desires, either in a forum or to a tube merchant, and get some reasonable recommendations. Without this knowledge you are just going to be spending money and time following generic recommendations from folks who don't have a clue as to what might really work for you in your system. 

Getting quality low noise tubes is easier - tubes can be tested for noise by the seller (most sellers anyway). Getting more power is easy - there are only a couple of tube types (KT120 & KT150) which offer this possibility and then only if your amp can use them. Most can't. 

Personally, when tubing an amp I start with power tubes and then fine tune the tone by changing small tubes. But that may be a bit advanced for some and it is easier, and cheaper, to play around with small tubes when first starting out if you just want to see what it is all about. 

Re your questions about how to hear differences between tubes - you are right about recycling amps on and off too quickly/often, and it does take new tubes time to break in. Small tubes sound best after 24 hours and big tubes can take up to 100 or more. As you can see, you really do have to develop a memory for your systems sound in the first place. And develop an objective.

Lastly, don't get taken in with some of the BS about NOS tubes being the finest, etc. A lot of them may be the finest, but because of that they are usually hard to find and very expensive. There are many new production tubes appearing on the market which are relatively inexpensive and very good, if not better than many NOS, if you know what you need in the first place. 

Take your time, it's a jungle out there. :-)