Category 5 Andrew- and Bias

[pbman1953]

I was checking bias on one of my amps and after I decided to check my buddies Cat 5 Andrew, which is also in my place space.




The amp has 2- SED Wing C 6L6's. Using my Bias Rite the voltage read 414 for both but the cathode was high.


The SED data sheet shows a 30 watt dissipation  and these came out at 28 & 29 watts.


The cathode current was at 68.2 and 73.8.


So I'm guessing these tubes are really cooking, plus there's no bias pot. I had my buddy get in touch with Cat 5 about this but I figured I'd ask if anyone has any experience with biasing a Cat 5.


Plus the amp is so sensitive to vibration. Any physical tap resonates through the speaker.


Thanks

[sluckey]

Not enough info. Is this amp fixed bias or cathode biased?

[pbman1953]

Should of mentioned , no bias pot. Does that help?

[sluckey]

You already mentioned that. Answer my question.

[pbman1953]

Can't answer, I don't know the amp that well.  Maybe others do.

[bnwitt]

http://category5amps.com/andrew.html

the specs say self biasing and custom cathode bias

[pbman1953]

Cool, I read that, thanks.


So how does cathode bias effect the tubes bias results? Is it suppose to run this hot? At almost full spec dissipation?


Or is that a question for Category 5 to answer?


Thanks

[bnwitt]

http://carlscustomamps.com/cathode-vs-fixed-bias/

how about some photos of the guts of that amp?

[sluckey]

Can't answer, I don't know the amp that well.  Maybe others do.

I'm trying to get you to look up some of this stuff for yourself. I've never heard of that amp but it only took about two minutes to learn that it was cathode biased.

Cathode biased amps typically run at about 100% max dissipation. Fixed biased amps usually run considerably cooler. Most people seem to like 70% max dissipation.

There's no problem running that amp the way it is.

[pbman1953]

Ok, i learned something today


Thanks

[sluckey]

Well it's a good day. 

[bnwitt]

Take the pebble from my hand grasshopper

[pbman1953]

Last night I talked to Don from Category 5. Great guy!


He explained about the ceramic cathode resistor bias. Plus, after a few questions , he wanted the amp back to go over some updates that it needed. There was also a capacitor that I sent him a picture of that was questionable. It was oozing out the end. He didn't like that. Plus the amp may be due for a transformer upgrade and they realized that the 270 ohm bias ceramic in now a 300 something because the 270 ran it too hot. Good thing I checked the amp because possibly the SED' C's could be cooked. He suggested to go back to the Tung Sol 5881 that came with the amp. The amp must be over 7 years old and they have moved on to other preamp tubes ,too. At the time they used a combo of Sovtek and JJ. Now they use Tube Amp Doctor and JJ. We talked talked about why he wouldn't go for seasoned oldies like Telefunken, Mullards, GE  or Amperex. He felt that he had to offer his customers something reliable that customers could get easily and give good performance.


He made a bass amp for Govern't Mule's bass player. Currently he's working on amps for Chris Stapleton and Brad Paisley.

[bnwitt]

I do believe Steven Scott is one of the principles of that company.  He used to be on the old 18 watt board years ago.  Also a very nice person.

[pbman1953]

You're right , he's listed as a contact on the website.




At this point we're talking to Berry, in the shop

[bnwitt]

Well if it is "Berry" instead of "Barry" that would be unusual.   Take it from someone who knows.

[pbman1953]

From: berry dickson


 

[bnwitt]

Is it a girl?

[pbman1953]

no idea

[bnwitt]

Gotta be.  I've never met a man named Berry.  I met one girl named Berry when I was in elementary school though.  Unfortunately people spell my name with an "e" often.

[sluckey]

I once knew a lad named Huckleberry. Does that count?   

[drew]

https://en.m.wikipedia.org/wiki/Berry_Gordy

[bnwitt]

https://en.m.wikipedia.org/wiki/Berry_Gordy

I think his mom wanted a girl   Actually Berry Gordy was a third from a line of male Berrys.  Typically for a male it is a derivative of Bernard.  For a girl it is botanical based.  Highest popularity of Berry 101 per million in the 50s.  For Barry it's 1,362 per million.  Barry is a derivative of Bartholomew  Mr. Gordy is out there by himself for the most part:

Famous real-life people named Barry: | Edit
Barry Bonds, baseball player
 Barry White, singer
 Barry Manilow, singer
 Barry Gibb, singer with The Bee Gees
 Berry Gordy Jr., founder of Motown Records
 Barry Lopez, American poet and environmentalist
Barry, the little boy in "Close Encounters of the Third Kind"
 Barry Allen, The Flash (DC comics)
 Barry Farber, ex-fiance of Rachel Green on "Friends" who she leaves at the altar in the pilot episode
 Barry B Benson, a GOD

[bnwitt]

I once knew a lad named Huckleberry. Does that count?   

I've been tempted to be a heckleBarry in some comedy clubs during bad acts.