Cary Audio CAD-280SA V12R

Nope, just 210ma per side, total.  If you get the fancy Cary meter to plug in, you'll likely check bias more, or a simple headphone 1/4" TRS type jack plug with wires and voltmeter.  Let amp warm up good, keep volume down or preamp off, set bias screw at 210-220ma per side (total), you can watch the LEDs (and start backing off) of course to get it close but watch the meter. One 1/4" old style headphone jack per side.  Nothing else to share or over-think there.  Or, just do as manual says, light up LEDS and back off, and then use the meter to fine tune side/channel down at tad till you get to 210-220ma per side.  Message me if you get stuck, will explain over the phone.  

Fancy one from Cary for $100:

Pic https://caryaudio.com/wp-content/uploads/2013/04/MA-300_front.png
Page, accessories
https://www.caryaudio.com/vacuum-tubes-and-accessories/

or, 1/4" headphone jack with loose wires to voltmeter.  




 

Its 35 ma per tube . 2 tubes per side = 70 ma. 4 tubes per side =140ma . 6 tubes per side = 210 ma . The manual is wrong , if you go to 275 ma with 6 tubes per side you will pop the fuse . I got a cheap analog milli amp meter on ebay and added the plug , it was like $30 . Only use 2 , 4 or 6 tubes in each channel . I tried a bunch of tubes but the electo harmonix sounded better than the rest ( disclaimer ...in my system ) . If you used matched tubes the leds will be a little closer when they light up and shut off but its not worth the cost for matched sets . Just buy regular sets and put them in = close enough . Its a mf badass amp .

bradluke0154 posts03-31-2020 6:56pmIts 35 ma per tube . 2 tubes per side = 70 ma. 4 tubes per side =140ma . 6 tubes per side = 210 ma . The manual is wrong , if you go to 275 ma with 6 tubes per side you will pop the fuse.


No fuse pops so far...But it sure sound good at 240ma total on the bias, I mean, there is quit a difference in SQ. I went as high as 260 from 240 with no SQ change, then backed off until it sounded REALLY good, not pretty good..REALLY GOOD. I'll rebias in a few days to 35 per an see if the SQ is as good...Could be a settling thing, my ears, or remember to take the cotton out of my ears this time...DUNO.. ;-)

I thought I was having a stroke... kept reading the same thing.. 210 210 210 total LOL.

So it's 35ma x every valve in pairs, per side. Wow hee hee. People say I ask too many questions.. Maybe.. but that's the old mechanic in me..I try to stay out of trouble, not GET OUT OF TROUBLE.

So:

1.  turn the unit OFF
 
2. turn both bias adj screws counterclockwise.

3. install or remove tubes in pairs per side, starting front to rear or rear to front. Not every other one, BUT in pairs per side in matched positions on the other side.

4. Hook up the bias meter, analog or digital..Digital is better (self diag and calibration)

5. With speakers hooked up (or dummy load), POWER UP turn the volume down on the preamp, and let the amp(s) warm up.

6. Adj the bias per rail @ 35ma for every valve in pairs. 70 (2),140 (4), 210 (6) are the prefered bias numbers, by turning the adj screw clockwise SLOWLY. recheck, recheck, recheck then recheck.
do the same on the OTHER rail. New valves, recheck in 6-10 hours rebias, as needed.

NOW

7. Don't worry be HAPPY. (You know like the song.. LOL) and turn the music...UP....:-}  <  happy Galic face, start doing the Irish Jig...

I'm so happy....

Thank you, Thank you, Thank you very much...

NOW, next problem... can you help me turn lead into GOLD...???

Just askin'..LOL

Regards

One thing I forgot to mention... This amp and neo 8 planars, no running out of gas, I've yet to crank it, BUT, at 49% volume, on the led, the Rabbit, the dog, and the hummingbirds start looking for shelter. No power issues, no distortion issues (the rabbit can't take it...)  :-)

Regards...

decooney226 posts03-31-2020 12:30amIt's just 210 div by 6, per "rail" as you noted.  If you are handy, pull lower cover, look and see if it has those four of the thin silver'ish Audio 1 coupling caps.

Yes it does, took pictures. Few other spendey little caps too. I saw the sokeys (sp) fast recover. Clean as could be..looks easy to work on.
Has a logic board in the back, front? Everything is point to point.
Wire to the speaker terminals was the only thing I didn't like.
I don't think it was #20, very small. that's gotta go. I have some really good pure silver # 12, 16, 18 wire. 16 will work, twice as big as what's in there..There was a bit of resin, around, alcohol will take care of it..

Regards