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Post subject: Blue Deluxe Reissue Bias Help
Posted: Fri May 12, 2017 11:16 am
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Recently I have changed my Blues Deluxe Reissue speaker with a Jensen Alnico in order to make the amp sound more vintage. Plus that, I have changed the factory bias from 59mv to 68mv. My purpose was to make the amp break up earlier with volume over 5. With the factory bias at 59mv the amp was not break up even at volume 10. Now with bias at 68mv I don't see any dramatic change. Could you please advise me for the bias value and how far can I play with without damaging the tubes? My aim is to make the amp break up with the volume at 5.
Thank you in advance,
Spy


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Post subject: Re: Blue Deluxe Reissue Bias Help
Posted: Fri May 12, 2017 12:52 pm
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Joined: Fri Feb 05, 2010 4:31 am
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Location: Province de Québec, Canada
A correctly biased amp will run efficiently and maximizes the life of your tubes.

Under - biased (hot ) amps will lack of punch and tubes will run hotter , shorter tube's life .
Overbiased amps ( cold ) will sound thin and brittle. with tubes running too cool for proper performance .
A correctly biased amps will sound clean and tight a moderate volumes, than at higher volumes breakup and distort musically .




Your Blues Deluxe have too cold bias if it use 6L6GC :(

59 or 68 mv is for both tubes ; 29 or 34 mv each tube if the are matched . Are they ?
Without reading plate voltage, bias MV is not accurate.

Schematic show 485 volts DC plates voltage. At 70% plate dissipation you can go safely to 86 mv for both tubes, 43 mv per matched tube for 6L6GC
6L6 ; 50 mv / 2 tubes

A higher MV bias drop plate voltage.
A lower plate voltage need more MV to drive tube at 70 %

Plates voltage reading is a must if you do not want to work like a blind or play lotto

Lethal voltage on tube amp


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Post subject: Re: Blue Deluxe Reissue Bias Help
Posted: Fri May 12, 2017 1:03 pm
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Thank you for the advice!


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