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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.)

 

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128x128mhwalker
newbee
4,093 posts
 
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. :-)




tomcy6's avatar
tomcy6
1,368 posts
 

I would only suggest that you not try fast A/B comparisons. Put your tubes in and listen for hours or days and then switch. Repeat until you decide which tubes sound best. If you can’t determine a difference, then you’re set with tubes for a good long while or you can resell them. Not as NOS of course, but if they only have a few hours on them you can state that in the ad.

I’m not familiar with the new production tubes available, but the reputation of many of the old stock tubes is deserved. It’s not BS, but you have to be careful buying them. There are plenty of less than honest sellers out there.

I suggest that you start by talking to Kevin Deal at Upscale Audio as he sells Cary and has a large stock of NOS and new production tubes.  He has probably retubed many SLI 80s.  You can check out his tube stock and prices at the UA website. The tubes will cost more than you can find elsewhere on the net, but his expertise will save you money in the long run. You will also be sure that you are getting the tubes you are paying for.

There are other reputable tube sellers that others will recommend and you can make up your own mind about who you prefer to deal with.

noromance's avatar
noromance
1,780 posts
 
Be careful not to get tied up trying to "fix" the sound with other swaps after you change one or more tubes.
r_f_sayles's avatar
r_f_sayles
827 posts
 
As  noromance commented, and I will add to, tubes, like cabling, IMHO should not be looked at as a "fix", but rather, a fine tune, tone control (especially with signal tubes). They are the finishing touch to a well composed kit. 
mhwalker's avatar
mhwalker OP
18 posts
 

Thanks for everyone’s responses - I appreciate your feedback and guidance!

 

I found Brent Jessie’s site and Joe’s Tube Lore very informative, and Andy Bowman’s Vintage Tube Services site looks fascinating. I've been hanging out at Upscale Audio's website a lot too (they recently changed the format of the site and I prefer the old version).

 

Looks like the consensus here is that the preamp tubes tend to have a bigger effect on sound quality than the output tubes (generally). Popular opinion on the ‘net seems to agree. I like newbee’s suggestion of “start with power tubes and then fine tune the tone by changing small tubes”.

 

>> One follow-up question: <<

 

  • When breaking-in tubes, does a musical signal need to be playing through them in order to break them in? Or is simply having the amp powered on enough to break them in?

 

Mostly due to crappy room acoustics, my current system tends to be lean in the bass/mid-bass region, and is easily excitable in the mid-highs and highs. I’m learning that I kind of enjoy that classic “tubey” euphonic sound – warm, rich, lush harmonics, slightly full bass, extended but smooth highs, etc. I was reading about the classic Mullard NOS sound as being that way, and the reviewer described it as having a “tweedy harmonic overdrive”. Fascinating how that makes sense to me.


To think of all the time I've spent listening to solid state, even good solid state, and have been missing out on what it turns out I actually prefer in tube sound.

 

Thanks again for everyone’s 2 cents!

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