If one wants to roll tubes, one can do so, but that is not a requirement. To me, it is a form of mental masturbation. Bias adjustment would be per the suggestion of the manufacturer. Some designs run the tubes harder than other designs (closer to their maxima for voltage and current). Such designs would benefit from bias adjustment at more frequent intervals compared to designs that run the tubes conservatively, because the tubes are wearing out faster in the former case. How often to replace tubes is also design-dependent. Vinyl is much more demanding than using a tube amplifier, on a day to day basis, IMO.
TUBE BIAS, socket to me!
BIAS: (I'm starting from zero understanding)
I have never measured/adjusted bias in the 3 tube amps, 3 tube receivers, and 2 tube preamps I have acquired over 47 years. I just switched my current Cayin from 6550's to KT88's. Adjust bias? Adjusters inside, scary electrocution warnings. I could pay someone else to do it, i.e. Steve at VAS 1 hr away in NJ, soooo,
What really counts? (personally I don't care about either heat or life, but would like to understand)
Heat?
Life?
Output stays Matched when adjusted?
Acoustic Performance?
_________?
Over the years, fronts off, bottoms off, I hose em down with contact cleaner/lubricant, compressed air, all controls and switchers, any adjusters, swish full spin back and forth. Kill any spiders, look for, replace the rare burnt resistor.
Then leave any adjusters (whatever they are) in the middle position, button it back up.
Two tube testers, my big hickock always agrees with small portable one, test strength, shorts, matched strength old and newly purchased. Large collection of NOS, used. Often used test essentially same strength as new ones.
When they go, it's usually a short.
I have never measured/adjusted bias in the 3 tube amps, 3 tube receivers, and 2 tube preamps I have acquired over 47 years. I just switched my current Cayin from 6550's to KT88's. Adjust bias? Adjusters inside, scary electrocution warnings. I could pay someone else to do it, i.e. Steve at VAS 1 hr away in NJ, soooo,
What really counts? (personally I don't care about either heat or life, but would like to understand)
Heat?
Life?
Output stays Matched when adjusted?
Acoustic Performance?
_________?
Over the years, fronts off, bottoms off, I hose em down with contact cleaner/lubricant, compressed air, all controls and switchers, any adjusters, swish full spin back and forth. Kill any spiders, look for, replace the rare burnt resistor.
Then leave any adjusters (whatever they are) in the middle position, button it back up.
Two tube testers, my big hickock always agrees with small portable one, test strength, shorts, matched strength old and newly purchased. Large collection of NOS, used. Often used test essentially same strength as new ones.
When they go, it's usually a short.
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- 91 posts total
Thanks @lewm. You didn't mention about tube testing - how often? I did think tube rolling was kind of just fooling/playing around, especially with newer tube amps. Day to day, of course, brushing the records and getting up to flip them every 20 minutes (or 10 with 45's) and handling the records (dealing with the sleeves, jackets and external sleeves and filing and removing them) is more time consuming than CDs, let alone streaming, but at this point, it is kind of a ritual. Do all tubes heat up the room, or is that a design function as well, the harder they run? Lastly, I have a SS phono stage. Does this reduce the potential benefit of an integrated tube amp? I got this about 9 months ago as before I used one in my integrated that was only adjustable between MM and MC with no variation on load or gain.I never knew how much better my system would sound with a dedicated phono stage versus the one that came with my amp. When I bought it, the cost of tube phono stages was substantially higher than SS ones, and I was told the lower cost tube ones were "noisy". Is this the case with integrated amps as well? Just doing some longer term planning/thinking. Thanks for your opinion. |
The amplifier itself is the best tube-tester. If a tube fails to bias correctly in situ in the amplifier, it should be replaced. Unless you want to spend thousands of bucks on a separate tube tester that can actually test power tubes at their typical voltage and current, you don't need a tube tester at all. This was mentioned earlier. The vintage tube testers, many of which are collected by strange people who collect tube testers, were generally NOT able to test power tubes at meaningful levels of voltage and current. Of those vintage testers, Hickok is the brand worth having, because Hickok testers along with only a few other brands can test transconductance. Testers ARE nice to have around for small signal tubes, used in the front end of amplifiers and in preamplifiers/phono stages. But even that is a bit frivolous. I do own a Hickok Model 533A, one of the older models probably from the post-WW2 era. I do use it to check transconductance (Gm), which is a sign of the life stage of a tube. If Gm is below the accepted range for that tube, you can ditch it with a clear conscience. I paid $75 for the 533A. The grandson of the 533 is the 539, one of the most sought after. A fully reconditioned 539 in top operating condition will cost you more than $1000, easy. 539s come a little closer to being able to test power tubes properly but not really close enough. I would bet almost no one here besides me owns any tube tester. I bought it for my own interest in DIY. |
@lewn, The statement below was from a positive feedback article about the MX110Z that Elliot was gracious enough to provide us. "Like me, after living with the MX110Z for a while, you may wonder why all modern preamplifiers don’t include FM tuners and equalization controls—they’re great fun! Also, tell me, is there anything even remotely comparable to the vacuum tubed McIntosh MX110Z currently available today at any price? No, which is a pity."http://www.positive-feedback.com/Issue77/vintage_mcintosh_experience.htm @ elliottbnewcombjr, Talk about a labor of love and patience! You kept the same preamp and kept it working after all these years. The money you've saved and knowledge gained on that unit, from not having that dreaded disease of upgraditis...Bloody brilliant if you ask me. As an Architect, whose path went the way commercial interior designer. I'd love to hear some of your stories on acoustics where the materials used were passive and maybe active in a room/hall you designed with the customers acoustic wants in mind. |
- 91 posts total