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TS808
February 18th, 2009, 05:59 PM
Just a question...If I were to replace the tubes in my Blackheart Handsome Devil, would this amp require biasing? I looked all over the internet and couldn't find an answer. I'm not sure if it is fixed bias, or if it would need to be re-biased. Thanks in advance.
markb
February 18th, 2009, 06:16 PM
It's in the manual. Yes, you need the bias adjusted when changing power tubes.

http://www.blackhearteng.com/pdf/BH15-112_OM.pdf

Scroll down to the "about tubes" section.
TS808
February 18th, 2009, 06:52 PM
It's in the manual. Yes, you need the bias adjusted when changing power tubes.

http://www.blackhearteng.com/pdf/BH15-112_OM.pdf

Scroll down to the "about tubes" section.

Thanks. I wasn't sure.
kiteman
February 19th, 2009, 09:37 AM
Oh oh, I retubed my BHHD haft stack with Mullard RIs without any biasing done.

Sounds fine to me though.
tunghaichuan
February 19th, 2009, 09:40 AM
Interesting. The manual never states for sure if the amp is fixed bias or not, it only alludes to it.

The only way to be sure is to either email Blackheart or open the amp up and look for fixed bias circuitry or a cathode bias resistor for the power tubes on the PCB.

tung
TS808
February 19th, 2009, 02:17 PM
Interesting. The manual never states for sure if the amp is fixed bias or not, it only alludes to it.

The only way to be sure is to either email Blackheart or open the amp up and look for fixed bias circuitry or a cathode bias resistor for the power tubes on the PCB.

tung
I wouldn't even have a clue what to look for lol.
tunghaichuan
March 3rd, 2009, 06:32 PM
Just got the schematic last night and had a look. The Handsome Devil is cathode bias. Interestingly enough, each EL84 has its own cathode bias resistor and bypass cap.

So to answer the original question, you can just replace the tubes without worrying about biasing the amp. I personally like to check the bias when doing so, but I'm anal retentive.

tung
tot_Ou_tard
March 3rd, 2009, 09:31 PM
I personally like to check the bias when doing so, but I'm anal retentive.

tung
That's not where the tubes are meant to go.
markb
March 3rd, 2009, 10:48 PM
Interesting. The manual never states for sure if the amp is fixed bias or not, it only alludes to it.

Manufacturers of guitar amps seem to never want to make any definitive statements about their products. I suppose it's better than false or misleading information though :)
Tele-Dave
March 4th, 2009, 12:27 AM
That's not where the tubes are meant to go.



Just spit on it, it will go in!!!