Tube Amp question:TUBE replacements: explain MATCHED?

 @moose89 -

            Lots of pics and info, available from this page:

https://www.google.com/search?q=cary+slm+100+for+sale&oq=cary+slm-100

                                       a review:

https://www.stereophile.com/tubepoweramps/cary_audio_design_slm-100_monoblock_power_amplifier/index.html

@immatthewj -

     I've looked for/at the smallest ammeters and (thus far): haven't found anything I could mount anywhere on my SLMs' chassis, for the convenience of not reaching for my Fluke.

     Hanging a couple on the amp stands and hard-wiring to the Bias jacks, would be a possibility, but: I'm SO lazy.

     Besides, it seems: with a good quad of output tubes in each monoblock, their relative biases seldom change.     Only: slight bias variations, consistent/the same in both, according to what's coming from the wall.

     The SLMs were my step, following the Rocket 88, which didn't have the juice to satisfy my SPL Jones (inefficient speakers, at the time).     No need to look further, as the SLMs' excellent transformers and circuit design made adequate power and the realism/presentation I sought, an easy reach, with judiciously chosen parts.   

     They were treated early on, to better RCAs, 5-ways and IXYS HEXFREDs.   Since: every cap has been upgraded (ie: Duelund cast-PIOs for coupling, ClarityCap ESAs in the B+, etc ).

     Of course: the optimum, NOS 6SN7 search was another enjoyable, illuminating and fun-filled journey.

                        Yeah: I'm FULLY invested in the SLMs, with NO regrets!

                                                     Happy listening!

     The nicest thing about buying that meter from Cary: it includes the same 3' test leads (with attached 1/4" plug), that came with my SLM100s.   

              Or: was it the Rocket 88 (Oldtimer's Disease strikes again)?     

                                                        Anyway:

     Would have been simple/easy to make my own, but I'm SO damned lazy: it was greatly appreciated! 

                    Then again: that IS a stiff price, for a mA dedicated meter.

     I WISH there were yet honest-to-goodness, NOS KT88/6550 valves out there, that could be described as, "reasonable".

     The supplies of Sylvania, GE, Genelex and Tung-Sol output valves, have long been dwindling and the prices (if they can be found): breathtaking.

     Even the authentic (before the St Petersburg plant was destroyed) SED =C= tubes are way up in price, IF/WHEN available (not often).    Funny (to older-than-dirt me, anyway), that tubes made as late as 2012, should be considered, "NOS", BUT: they did come close to the presentation of the afore-mentioned champs.

@moose89 -

     The information that blackdoghifi gave you, regarding YOUR Cary amp’s output tubes and why THEY should be a matched set, is absolutely correct.

      Given that all 4 of your valves share one bias voltage; not having a matched set MAY result in crossover/notch distortion, which is never good.

                                   Also: immathewj’s instructions = +1

I just looked at the bias instructions for the 808 and the bias is adjusted by the same procedure as the two Cary amps that I own. A plug (with a + lead and a - lead) insert into a receptacle in the back of the amp; you will need a multimeter that will read DC milliamps. Connect the leads from the bias plug to the leads on the multimeter (the Cary bias plug leads have alligator clips on them) and after the amp is warmed up, you can adjust the bias pot. I always back my bias pot all the way down and start from scratch when installing new output tubes or lugging the amp in at an unfamiliar environment.