to have a penta tube set crap out on you twice ? has me thinking was it something at your end,or is the tube quality lacking? now im pausing longer on a decision of penta 572b? and their overall quality? anyone ?
I just got off the phone with Scott, KB1SEL (amprepairguy.com) who is also a Penta dealer. He rarely has 572B issues. Penta ships him dozens per week....(including 3-500Z's). That's why I was asking abt incoming line V. IF the fil V is on the high side, that could reduce tube life. To get 750 w out of a SB-221, with 220 vdc loaded would require 500+ ma.
He uses the 572B's in the ameritron 3 and 4 tube 811 amps, and also the 4 x 572B ameritron amps, and also SB-200's and SB-201's. Nobody is flattening Penta 572B's in 14-15 hrs.
Funny there's another Scott at Penta labs that I've been talking with Scott Cegielski and for some reason he doesn't seem surprised especially when I asked if they would like more operating details of my amp and the tubes.
I impressed you're jumping to their defense, I'm certainly not attacking anything about them, as Scott said they do the best they can with the incoming stock from the one and only Chinese supplier they have been using.
ONCE AGAIN I WOULDN'T HESITATE TO BUY FROM THEM IT'S THE BEST OPTION!
Oh and yea that's the right math .500 ma I agree!
Just got off the phone with Scott Mitchell, KB1SEL...(amprepairguy.com). If you are running the SB-200 / SB-201 at 750 watts out, you are running it too hard. Back the drive down, and re-tune it for 600 watts pep out. Then the tubes will last. That's just the way it is with those Chinese tubes. Nobody is gonna hear the .97 db difference.
Nope I don't run it at constant 750 watts lol OMG really that's how you understood that?
I simply stated that as a test I can get a solid 750 watts through a known bird slug into a 50 ohm load.
That should NEVER shorten any tube life, once again the exact same amp.
I simply plug in the 40 year old Cetron 572B's and it will hit that 750 watts no issue after over 100 hours in this amp over a 40 year period!
I have no idea where your friend gets his awesome tubes but Penta Labs has told me more then once it may "take a few tries to get a good pair that will stand up".
This is exactly why I built a solid state amp, I can just count on that one pair of Cetrons as a back up still.
I just stop using the amp with Chinese tubes and problem solved.
It will continue to serve it's purpose probably long after I'm dead with those same Cetrons lol.
Yea haven't been running any amp in my entire life at it's maximum power other then very short tests, most folks normal in the head don't do that unless they are rich and don't mind swapping out equipment a lot.
