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In Reply to: RE: New Cary SLI-80 signature owner has questions posted by petercapo on August 14, 2014 at 06:01:48
Do you know what the info on the EH tubes that looks like a date means? My amp has tubes with "12 05" and "12 02" and "02 04", etc., on them. If its a production date my amp has new tubes which are actually up to 12 years old.
I installed them mirror image symmetrically according to the "date".
Follow Ups:
You might actually need to install the power tubes in the order of the numbers on the boxes, 1 through 4, from left to right on the amp, if the boxes were so numbered. That's the way mine came along with instructions to do it that way. I have assumed that meant they are matched at the factory and need to be installed in that order so that the matched pairs stay together in each channel. However, in your case, if all four were properly matched together as a quad, then the installation order would not matter.
Those date codes are in a year-month format.
The age of the tubes does not really matter, as long as they are good. What matters is that they are electrically matched, accordingly. Personally, I also feel that it could be very beneficial to have date codes matched (or very close) as well, for channel-to-channel (left-to-right) consistency in sonic characteristics. I am sure some will disagree with this, but I strive for it.
If you ever replace the power tubes, buy them from someone who can match them at the plate voltage you can expect in the SLI-80. Cary quoted me figures in the high 500’s of volts, but I have not yet had a chance to measure it in my SLI-80 myself. I suggest tctubes.com
Thanks Peter! The EH power tubes all had a "54" label on the top of their individual boxes, so it appears that they are a matched quad. I think I'll switch the mirrored image arrangement (based on date codes) that I use and adopt the matched pair date codes as you suggested. That would put two 12-05 tubes on the left side and two 12-12 tubes on the right, and then re-bias them.
Terry
Actually... I don't think I was as clear as I should have been. If there is anything to my idea about date codes, I think your mirror imaged arrangement would be better, that is, a 12-05 and a 12-12 in each channel, again assuming they are indeed a matched quad.
Edits: 08/19/14 08/19/14
Cool, I'd rather listen than re-bias. Thanks again for all the info and guidance on tube rolling. I'm planning to put about 75 to 100 hours on the EH tubes prior to considering tube rolling but I'm sure I will tube roll! All of the current tubes are EH -- signal, driver, power, rectifier.
Conventional wisdom states that the amp should always have a signal going to it . Turn it on last and off first .
I would also suggest that you put 200-300 hours on everything , tubes and amp , before you make any decisions on the sound .
When I demoed a Sli-80 , I switched from UL to triode on the fly without any problems or noises , as suggested by the dealer .
Good luck
saki70
Thanks saki70! I'm definitely hearing changes as it continues to break-in. Some of the tube break-in sound mentioned by another poster is spot on to what I'm hearing, so it's going to test my patience to wait 200-300 hours. But I've experienced that type of extensive break-in with other components, the Plinius 9200 and a Shunyata Python CX power cord for example.
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