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Posted: Thu Nov 25, 2010 7:48 pm
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Rock Star
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babatube wrote:
you got me
but i know ear biasing :lol:

i never claimed to be an electronic guru.
i used suggestions from other people who experimented and let my ears decide.


Ear biasing can get you and your amp in trouble. The proper tools make biasing an amp simple and safe. All you need is a bias probe and digital voltmeter. Do a search in this forum as there have been many discussions on proper biasing of these amps with suggestions on which tools to buy. Cheap insurance to protect an expensive investment.

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Posted: Thu Nov 25, 2010 7:51 pm
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bluesky636 wrote:
Cheap insurance to protect an expensive investment.


+1000!

Arjay

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Posted: Thu Nov 25, 2010 8:08 pm
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Aspiring Musician
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Hardly a tube guru. I have a BSEE (1976), but most of what I learned about guitar amps I learned from the many more knowledgable people in this forum.


Wow! I was still in high school. +1 on the knowledgeable people on this forum.


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Posted: Thu Nov 25, 2010 8:37 pm
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rjake wrote:
Quote:
Hardly a tube guru. I have a BSEE (1976), but most of what I learned about guitar amps I learned from the many more knowledgable people in this forum.


Wow! I was still in high school. +1 on the knowledgeable people on this forum.


Please don't make me feel any older than I already do. At least you didn't say you weren't even born yet. :lol:

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Posted: Thu Nov 25, 2010 11:11 pm
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Quote:
All you need is a bias probe and digital voltmeter.


i did use digital volt meter.
but let my ears decide on the final result.
i don't really care what's the percentage of the plate dissipation.
all i know that in the HRD biasing the GT6L6CHP to 74mV is a magic spot.

when i will bias a different amp i will come and ask you for help :P
probably not in the near future because
i like my HRD too much. i tell my wife i'm in love with it :lol:
she tells me that she figured that out by herself already...


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Posted: Fri Nov 26, 2010 12:11 am
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babatube wrote:
i don't really care what's the percentage of the plate dissipation.


Now there's a man who knows what he wants, folks!

:roll:

Arjay

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Posted: Fri Nov 26, 2010 6:33 am
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babatube wrote:
i don't really care what's the percentage of the plate dissipation.


To be honest, that kind of thinking can come back and bite you in the butt.

babatube wrote:
all i know that in the HRD biasing the GT6L6CHP to 74mV is a magic spot.


What is a "GT6L6CHP"? I am not familiar with that tube? Do you know what the specs for that tube are? What is the maximum plate dissipation? 20 watts? 25 watts? 30 watts? What is the maximum plate voltage it can safely handle? Without knowing those values, just setting the bias pot so that the voltage at the Fender test point reads "xx mV" can easily damage a tube. There have been multiple variations of the 6L6 power tube through the years, each with different specifications. Just saying that a "tube is a 6L6 so I can set it to X" can be problematic. The only 6L6 I am really familiar with, and hence comfortable with, is a true 6L6GC.

babatube wrote:
when i will bias a different amp i will come and ask you for help


As noted above, its not necessarily a case of "when (you) will bias a different amp", but when you bias a different tube than what came stock in your HRD. In my BDRI, the JJ 6L6GCs sound absolutely fantastic, great blues tone, when biased at 85 mV at the Fender test point, but I also know that the measured cathode current, (calculated) plate current, and plate voltage are in a safe range for the tube in question. Those same settings may also sound good with the tubes used in your HRD .... for awhile.

Please understand that we are not trying to pick on you. We just want you (and others) to understand the full picture when it comes to properly biasing your amp in order to prevent future problems. I was not aware of these issues when I got my first tube guitar amp. Even with my EE degree I had not looked at a vacuum tube in over 30 years. :lol: :lol: :lol:

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